EBCS-10.pdf

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Ethiopian Building Code Standard

ELECTRICAL INSTALLATION OF BUILDINGS

Ministry of Works & Urban Development Addis Ababa, Ethiopia

1996

S661 ,,¢o~a

"'q"qy sWpy ~owdoloAoa tmcpn 19. S)Jl0A\.,J0 A.1lsMW

e

I

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E;BCS-lO Electrical 1'onallatloDof lIluitdings

Pr()ject toul1tll Mtmbtrs

'rethnfcal Members

Abashawl Woldemariam (ChaiI1mm) Aletnayehu tnzilwt Bekele Mekonnen Negussie Tebedge

Mohammed A

Seifu 8ir~e

Wouhib Kebede t I>eceaSedbefote ~mpletionofthe PrOject.

Editors

Electro Data Processing &, Publishing. Addis Ababa

B~kar (Secretary)

Alemayehut3izawt Admassu Gizaw tarekegn Abay tesfaye Bayou

FOREWORD

The Proclamation to defme the powers and duties of the Central and Regional Executive Organs of the 'Transitional Government of Ethiopia No. 41/1993 empowers the Ministry of Works and Urban Development to prepare the Country's Building Code, issue. Standards for design and construction works, and follow up and supervise the implementation of same.

In exercise of these powers and in discharge of its responsibility, the Ministry is issuing a .series of Building Code Standards of general application. The purpose of these standards is to serve as nationally recognized documents, the application of which is deemed to ensure compliance of buildings with the minimum requirements for design, construction and quality of materials set down by the National Building Code. The major benefits to be gained in applying these .standards are the harmonization of professional practice and the ensuring of appropriate levels of safety, health and economy with due consideration of the objective conditions and needs of the country. As these standards are technical documents which, by their very nature, require periodic updating, revised editions will be issued by the Ministry from time to time as.appropriate. The Ministry welcomes comments and suggestions on all aspect of the Ethiopian Building Code Standards. All feedback received will be carefully reviewed by professional experts in the field of. building construction with a view to possible incorporation of amendments in future editions.

Haile Assegidie Minister Ministry of Works and Urban Development 1995

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I N T ROD U C TI 0 N

This Code Standard for the Electrical Ins tallation of Buildings is part of the Building Code of Ethiopia: .

.

This Code Standard for the Electrical Installation of Buildings is mainly adopted from lEE Regulations for Electrical Installations and Canadian Electrical Code, Part 1, to suit the Ethiopian conditions. Other publications quoted are shown in the respective sections of the Code and the Ethiopian Authority for Standardization maintains registers of a national and international standards. number of, foreign . The Code embraces several aspects of electrical installation work and sets standards and provisions for safe utilization of electricity. The Technical Committee for Code Standards for the Electrical Installation of Buildings comprises of the following Institutions representing balanced interest of all segments of the public concerned with the subject matter: • Ministry of Works & Urban Development (MWUD) • Building Design Enterprise -(BDE) • Ethiopian Electric Light & Power Authority (EELPA) • Addis Ababa University, Faculty of Technology (AAU) • Ethiopian Authority for Standardization (BAS).

'ETHIOPJAN BU,LDING CODESTANDAAD

EBCS-10 ELECTRICAL.IN·STALLATION OF,

BUILDINGS

TAB:LE OF CONTENTS

Section 1 1.1

1.2 .1.)

Section 2 2.1

2.2

SCope And Definitions Scope '. . . . . . . . . . Nonnative references ' ,. Definitions..... . . . . .. . . . . . . . . . . . . . . .' . : . . . . . . . . . . .. • . . .' .' .. Gen~ral

1

1

2

Requirements

Acbninistrative.. . . . . . . . . . . . .' . . . .. . . . . • .. . . . . . . . . • . .' . . .. . . .. 2.1.1 Authority for rules . . ...•...•._• . . . . . •..". . . . . . . . . . , . " 2.1.2 Pennit ' .....•..........•..' _. . . . . . . .. 2.1.3 Application for inspection ......•. " . . . . . . . . ..'. . . . .' . . .. 2.1.4 Posting of permit .... ',_ .' . . . . . . . . . . . . . . . ...' .' .- .... . .' .- •.- •• 2.1.5 Notification re-inspection .....................•.•..... 2.1.6 Plans and specifications. . • . . . . . . . . • . . • . . .. . .. -. •. . . . . .. " 2.1.7 Connection authorization ......•...•....2.1.8 Re-inspeetion -•......•...-•., -...•..-., ..,... 2;L9 Renovation of existing installatiOn 2.1.10 Use of approved equipment . . . • . . . . • . . . . . . . . . . . • . . . . . .. 2.1.11 Deviation or postponement .................•.......... 2.1..12 PO-wers of rejection . . . . . . . . . .. '" . . . . . . . . . . • . .. . . . . . .. 2.1.13 InStallation of electrical equipment . . . .•...-. . • . . • . .' . . . .' • • .. 2.1.14 Damage and interfer""~e . • . • . . . . . . . • . . . ;, . . • . • . . . ~ • . . .. Technical 2.2.1 Conventional symbols . . . . . . . . . . . . . . . . ._. • . . . . . . . . . . . •• 2.2:.2 Co-ordination· -.........•' 2.2.3 Lo-cation and requirement of substation . . . . . . . . . . . . . . . . . ... 2.2.4 Rooms (spaces) required . . . • . . . . . . ~ . . . . . . . . . . . . . . . . . .. 2.2.5 Location and requirements of distribution boards . . . . . . . . . . . " 2.2.6 Location and requirements ofPBXlPAB-X rooms " o"

• • •-

• • • • • • • •-

• • • • • • •-

•••

-• • • •'

• • • • • • • •' .

20'

20

20

20' 20'

20~

21

21

21

21

22

22

22

22

22

2J;

n,

n

23

23

24

24

I;

2.3

Planning and designing ~....... . .-.......................... 2.3:1 General " . . . . . . . . . . . . . . .. 2.3.2 Layout and installation drawing 2.3.3 Design

25

25

25

25

2.4

'. . ,~ . . . . . . .. . . . .. . . . . . . . . . . . . .. Marking of equipment 2.4.1 General.......;.................................. 2.4.2. Workmanship and materials '. . . . .. 2.4.3 Material for anchoring' . . . . . . . . . . . . . .. . . . . . .. . . . . . . . .. ' 2.4.4 Protection of persons and property . " 2:4.5 Maintainability..................................... 2.4.6 Enclosures........................................

26

26

27

27

27

27

28

, Section 3

II

Dluminstion

3.1 3.2 3.3 3.4

Scope ' " Normative references. . . . . . . . . . . .. . . . . .. . . . . . . . . . . . . . . . . . .. Definitions , " Lighting requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. ,...... 3.4.1 Illuminance 3.4.2 Luminance ' ; , '. . . . . . . . . . . . . .. 3.4.3 Glare· ' 3.4.4 Light direction and modelling 3.4.5 Colour rendering

29

29

30

35

35

35

36

36

36

3.5

~ . . . . . . . . . . . . . . .. Emergency lighting requirements 3.5.1 Escapelighting 3.5.2 Safety lighting for particular hazardous workplaces 3.5.3 Standby lighting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

37

37

37

38

3.6

Lighting requirements for various types of buildings . ,........... 3.6.1 General 3.6.2 Industrial......................................... 3.6.3 Offices ' ', . .. 3.6.4 Hotels and restaurants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3.6.5 Educational establishments . '" . . . . . . . . . . . . . . . . . . . . . . . . . . ,......... 3.6.6 Hospitals ,

, 38

38

39

39

39

40

40

3.7

Outdoor lighting requirements 3.7.1 Illuminance....................................... 3.7.2 Colour rendering group. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. ,. 3.7.3 Limitation of glare 3.7.4 Lighting of outdoor fixed location work spaces

42

42

42

43

43

Section 4

Conducton

4.1 4.2 4.3 4.4

Scope "'. ". " ' Nonnative references. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Defmitions , . . . . . . .. Size of conductors 4.4.1 Phase conductors in a.c, Circuits and live conductors in d.c. circuits.. 4.4.2 Neutral conductors ....•......... ' '.

4.5

Ampacity of wires, cables and flexible cords 4.5.1 Conductor operating temperature 4.5.2 ,Cables connected iri parallel 4.5.3 Cables connected to bare conductors or busbars '4.5.4 Voltage drop ~ ~

4.6 4.7 4.8

Flexible cords ' ',' Colour of conductors Maximum permissible temperature

~

:.......... 70

; ~ . .. 70

-: . .70

. . . . . .. 70

',' .. ". 70

'.' . . . . . . . . . . . . . . . . . • . .. 70

; . . . . . . . . . . . . . . . . .. 71

'.. . . . . . . . . . . . . . .. 71

Annex. (preface) Annex A (Nonnative) - Correction factors Annex B (Nonnative) - Type of cable and ampacity

Section 5

74

85

90

Service And Service Equipment

5.i

Scope ' .. ; ' '.' 5.2 Nonnative references 'j' • • • • • • • • • • • • • • • • • • • • • • • • • 5.3 Defmitions ·.......•· 5.4 . General requirements ..............................•. ~ 5.4.1 Number of services permitted 5.4.2 Consumer's installation not to be supplied through another building. . .. 5.4.3 Conductors considered outside ofa building 5.4.4 Other conductors in raceway or cable' 5.4.5 Clearance from building openings ,

5.S

66,

66

67

69

69

69

Service equipment 5.5.1 ' General 5.5.2 Control

,

'

'

;

141

141

141

142

142

143

143 .

144

144

144

l44 . '.. 145

III

5.6 . Wiring methods . . 5.6.1 Underground consumer's service conductors 5.6.2 Overhead consumer's service conductors

148

148

148

5.7

149

149

Section 6

Metering equipment 5.7.1 Connection

,

Circuit Loading and Demand Factor

6.1 Scope 150

6.2 . Nonnative references , 150

6.3 Defmitions................. . . . .. . . . . . . . . . . . . . . . . . . . . . . • . 'ISO

6.4 General............................................... 151

6.4.1 6.4.2 6.4.3 6.4.4 6.5

Services and feeders 6.5.1 6.5.2 6.5.3 6.5.4 6.5.5 6.5.6 6.5.7 6.5.8

Section 7

7.17.2 7.3

IV

Current calculation . . . . . . . . . . . . . . . . . . . . . . . . .. '.' . . . .. . 151

151

Voltage drop .•.......................... : Maximum circuit loading 151

'.' . . . . . . . . . . . . . 151

Use of demand factor 151

Single-family dwellings. . Apartment and similar multi-family buildings "' Schools Hospitals ;

151

, 152

153

153

Hotels, motels, dormitories, and buildings of similar occupancy 154

Other types of occupancy ..•.......................... )55

Branch circuits 155

Feeder demand factors for lifts 155

Earthing, Bonding, and Lightning Protection Part I - Earthing. and Bonding Scope .....................•........' Nonnative references System and circuits earthing 7.3.1 Direct current.systems 7.3.2 Alternating - current systems . . . . . . . .. . . . . . . . . . . . . . . . . . .

157

157

158

158

158

7.4

Location of system earthing connections ~ 7.4.1 D.C. systems 7.4.2 A.C. systems 7.4.3 Isolated systems '.' 7.4.4 Single service supply to two or more buildings or structures 704.5 . Conductors to be earthed 7.4.6 Current over earthing conductor ~

159

159

l59

}·59 160

; 160

160

7~5

Bonding 161

75.1 Non-current carrying metal parts 161

1.5.2 Exposed non-current-carrying metal parts of equipment •....... 161

75.3 Non-metallic wiring systems i61 161

7.5.4 NOll-electrical services 164

7.5.5 Extraneous fixed metalwork

7.6

Method of earthing . . . . . . . . . . . . . . . . . . . . .. , . . . . . . . . . . . . . .. '. 164

7~6.l 7~6.2

7.6.3 7.6,4 7;65 7.6.6 7.7"

Effective earthing .............•......" " Common earthing conductor .....•...................... Common- earthing electrode :Underground service ; Short section of raceway Fixed equipment

Bon-ding methods

73:1

_. . . '.' . . . . . . .. . . . .'. . . . . . . . . . . . .. 166

Clean surface . . . . . . . . . . . . . . . .'. . . . . . . . . . . . . . . . . . . . . . Bonding at service.equipment. , Means of assuring continuity at service equipment ....... Metal armour or tape ofservice cable ' Bonding at other than service equipment ; . . . . . . . . . . . . . . . . . . Loosely jointed metal raceways .•.......................

1.7:2 7.7.3 7.7.4 7;7.5 7.7.6 7.7;7 Bonding jumpers 7Jl

164

164

164

165

165

165

Earthing electrodes

7.8.1 General 7.8.2 Service pipe electrode 7.8.3 Artificial earthing electrodes

:

166.

166

166

167

167

167

167

168

168

168

169

v

. _ - - - _ . " .. , _ . , . - -

7.9

,.,_ . .

Earthing and bonding conductors 7.9.1 7.9.2 7.9.3 7.9.4 . 7.9.5 7.9.6

0

•••••••••

General Installation of system earthing conductors Installation of equipment bonding conductors Earthing conductor size for d.c. circuits Earthing conductor size for .a.c, system Bonding conductor size 0

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• • • • • • • • • • • • • ,

0

0

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0

0

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7.10 Earthing and bonding conductor connections 7.10.1 7.10.2 7.10.3 7.10.4 7.10.5

Section 7

171

172 173 174

174

174

, 175

Bonding. conductor connection to raceways Earthing conductor connection to water pipe electrodes, Earthing conductor connections to other than water pipe electrodes .. Bonding conductor connection to circuits and equipment .... o' •• Earthing conductor connection to electrodes' ...............•

175 ' 175

175

176

176

Earthing, Bonding and Lightnin~ Protection ' Part Il - pghtning Protection

7.11 Scope ...

178 '. . . . . . . 178

7.12 Nonnative references, 7.13 Definitions . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . J 79'

7.14 Materials . . . . . . " . . . . . . . . . . . . .. " . • . . . . . . . . . . . . . 180

7.14.1 General 180 7.14.2 Galvanic compatibility '," : 180

',' .. 181' 7.14.3 Corrosion protection , 7.14.4 Mechanical protection ..............•................. 181

7.14.5 Use of aluminium ..........•.•. : 181

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7.15 Fonn 7.15.1 7.15.2 7.15:3 7.15.4

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and size . . . . . . . . . . . . . Air termination Conductors Earth termination Minimum dimension 0

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VI

184

.184

185

185

185

' • • • • • • • • • •

7.16 Air termination . . . . . . . . . . . . . . . . . . . . . . . . . . . . " 7.16.1 General " 7.16.2 Support ' " 7.16.3 Metallic projections 7.16.4 Metallic materials, ~ 7.16.5 Structure within zone of protection 7.16.6 Air termination on roof ' 7.16.7 Air termination on reinforced concrete structure . . . . . . .. . . . . . 0

, I

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185

185 185

.185 186 ' 186

186

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7.17 Down conductor . . . . . . . . . . . . . . . . . . '. . . . . . . . . . . . . .. , . . . . . . ,.:J86

7.17.1 General · 186

'.' .. '......•............ : .' '187

7.17.2 Routing 7.17.3 Recommended number 187

7.17.4 Mechanical protection " .: 187

7.17.5 Corrosive soil ; 187

7.17.6 Extemal routes not available ; 187

~ ; " : 188 7.17.7 Lift shafts 7.17.8 Re-entrant loops 188

'.' 188

7.17.9 Sharp bends 7.17.10 Bonding to prevent side flashing 188

7.17.11 Bonds ; 188

7.17.12 Test points : 189' 7.18 Earth termination 7.18.1 7.18.2 7.18.3 7.18.4

••••••••••

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190

Termination ........•. '.' .' 190

~ . . . . . 190

Resistance to earth Eart.h electrodes . . . . . . . . . . . . . . . . :.. . . . . . . . . . . . . . .. . . . 190

Connection point ;' 190

7.19 Common earthing

192

:

7.19.1 Common earth potential .; '.' 7.19.2' Common earth bonding

, .. ' ;

192 '

192

7.20 Use of reinforcement for earthing inconcrete Structures .....:....... 193

7.20.1 General 193

7.20.2 Electrical continuity . .. . . . . . . . . . . . . . . . . . . . . . . . . . 193

7.20.3 Prestressed concrete members 193

7.20.4 Precast concrete members 193

7.21 Structural steel framing for lightning protection '. . . . . . . . . . . ',' . . 7.21.1 General ... . . '" . . . . . . . . . . . . . . . . . 7.21.2 Air termination 7.21.3 Connection .................'.......;............... .. " . . . . . . . . . . . . . . . . . . . 7.21.4 Earthing 7.21.5 Interconnection '

194

194

194

194

194

194

Annex (Informative)

Annex A - System design . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . .. . . 219

Annex B - Consultation .. . . . . 220

VII

Section 8

Wiring Methods

-8.1 Scope..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . 223

8.2 .Normative reference ; ...........•....... 223

8.3, General requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223

8.3.1 Methods of installations 223

8.3.2 Wiring in ducts and plenum chambers ~ . , 224

8.3.3 Underground installations,

224 8.3.4 Conductors in hoistways

225 8;4

Conductors

8.4.1 Types of conductors

8.4.2 Radii of bends in conductors

8.4.3 Conductor joints and splices

8.4.4 Supporting of conductors

8.5

Open wiring . ','

226 226 . . . . . . . . . . . . . . . 226 227 228 "

8.5.1' Open and clipped direct

8.5.2 Spacing of conductors

8.5.3 .Conductor supports

8.5.4 Spacing of supports

'

228

','

228 228 229 229

8.6

Exposed wiring on exterior of buildings and between Building's on the samepremises 8.6.1 Location of conductors , 8.6.2 Clearance of conductors 8.6.3 Power supply conductors

8.7 8.8

Bare bus bars and risers Installation of boxes, cabinets, outlets and terminal fittings 8.8.1 Number of outlets per circuit 8.8.2 Outlet boxes 8.8.3 Conductors in boxes 8.8.4 Terminal fittings

8.9

Cables, conductors .and wiring methods

'

Annex A (Normative): Schedule of methods of installation of cables

Vlll

;

,

229

229

229

229

230

230

230

',' . 231

231

,231 232

233

Section 9

I

Protection'and Control

9.1 Scope ~ . ~ 9.2 Nonnative references 9.3 General requirements 9.3.1 Protective and control devices 9.3.2 Types and ratings of protective and control devices

~

'

2:37

237

237

237

238

9.4

Protective devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238

9.4.1 Overcurrent devices 238

9.4.2 Earth fault protection 239

9.5 9.6 9.7 9.8 9.9

Fuses ' 240

Circuit breakers 240

Control devices . . . . . . . . . . . . . . . . . . . . .'. . . . . . . . . . . . . . . . . . . . . 240

Switches \., 241

241

Protection and control of miscellaneous apparatus

Section 10

Class 1 and Class 2 Circuits

10.1 Scope 10.2 Normative references 10.3 Classification 10.3.1 General 10.3.2 Class! extra-low-voltage power circuits 10.3.3 Class 2 low-energy power circuits 10.3.4 Hazardous location 10.3.5 Circuits to safety control devices 10.3.6 Circuits in communication cables

,

,

10.4 Class 1 circuits . . . . . . . . . . . . . . . . . . . .' . . . . . . . . . . . . . . . . . 10.4;1 Limitation of Class 1 circuits 10.4.2 Methods of installation for Class I circuits 10.4.3 Overcurrent protection of Class 1 circuits 10.4.4 Location of overcurrent devices in Class 1 circuits ., 10.4.5 Class I extra-law-voltage power circuit sources including Transformers . 10.4.6 Conductor material and sizes 1004.7 Insulated conductors for Class 1 wiring .' " ~ 1004.8 Conductors of different circuits in the .same enclosure, cable, or Raceway 1004.9 Mechanical protection of remote-control circuits 1004.10 Class 1 circuits extending aerially beyond a building

245

245

245

245

246

246

246

246

246

247

247

247

247

247

248

248

248

248

249

249

IX

~ .. I

Section 13 Flammable Liquid Dispensing and Service Stations, Garages, Bulk Storage ,.. Plants,Finishing Processes and Aircraft Hangars <,

13.1 Scope . ~ . . ", 13.2. Nonnative references ' 13.3 Gasoline dispensing and service stations 13.3.1 Hazardous areas , 13.3.2 Wiring and, equipment within hazardous areas ~3.3.3 Wiring and equipment above hazardous areas

"

294

295

295

295

296

297

13.4 Commercial ~arages, repairs and storage 13.4.1 Hazardous areas 13.4.2 Wiring and equipment in hazardous areas 13.4.3' Wiring above hazardous areas 13.4.4 Equipment above hazardous areas

297

297

298

298

298

13.5 Residential storage garages 13.5.1 Non-hazardous location, 13.5.2 Hazardous location. ; : 13.5.3 Wiring . ' ".:'

298

298

299

299

13.6 . Bulk storage plants .'." .....•......... " . 13.6.i Hazardous areas .: . '. ..•......................... 13.6.2' Wiring and: equipment in haz~dous'areas 13.6.3. Wiring ~d equipment.above hazardous areas '

299

299

302

302

13.7 Finishing processes', .. , . "." .. '., .' .. " "'" . " .. , 13.7:1 Hazardous 'locations 13.7.2 Wiring and' equipment hazardous areas ...•.............. 13.7.3 'Yiring and equipment above hazardous areas

302

302

304

305

in

'13.8 , Aircraft hangars ; "" ' , .: 13.8.1 Hazardous areas, ' '.. ." 13.8.2 Wiring .and equipment in ·hazardous.'areas

: .~ 305

\ .. :•............ 305

,. '.•,' 306

13.8.3, Wiring not within,'hazardous area. ','. "'~ .': . '." ~ 13.8.4 Equipment-not within hazardous' areas: . ~

306

307

Section 14 Patient Care' Areas 14.1 Scope' 1.4.2 Normative references

XII

'.~

'

; .............•: .. : : '

; ~.'

308

308

----~-~--~

14.3 Definitions, , 14.4 Circuits in basic care areas. , ,

, .. " . " . , . , ~ '30'S' , , .. , . , .. , . , .. , , .. : .3'1 f ,

, , , .. ,

14.4.1 Branch circuits. , , , , .. , .. , . , , , ', '.' 14.4.2 Bonding to earth in basic-care areas , , ; , 14.4.3 Socket outlets in basic-care areas .,"',.:., ' •: 14.5 Circuits in intermediate and critical-care areas .. ',., '

, .• , . 311 "" 31.1 : 312

,.,

313

, ,.. , . , ., .. , .. 313

14.5.1 Branch circuits ; .. ' . , 14.5.2 Bonding to earth in mtermedlete andoritical-care areas 313

14.5.3 Receptacles in intermediate-and critical-care areas , , .. 313

14,6 Isolated systems

"

" .,.,

14,6.1 Sources of supply. , , , " ' ' '.' . , 14.6,2 Single-phase isolated circuits , .. , .. , , ;

'.' '.: ,

14.6.3 Three-phase isolated systems

,

,"'

14.7 Essential electrical systems, ,

,

,

14.7.1 Circuits in essential electrical systems .. ;.' 14.8 Transfer switches ., 14,9 Emergency supply .. ,

; , , ~ .:.. , 314

, .. : 314·

' 314

, .. , .: . 315

,,

315

~ ,

, .. , .. 315

, ".: '..... , " ... ,' ... ~ : .. , ... '.' .. , , : .. 316

,.. ,.",; .. " .. ; .. ,.,., ..,:, .. :, ... ,',316

Section IS Installation of Lighting Equipment 15,1 Scope "." , , .. , .., '.' '.' .. , " '.' ', '.;,' , '.' . , , ~18 15.2 Nonnative references , . ... , . .'. . '.' , . " . .' . , ' ~.,'. .,.. " .. '. ' . . , ,. , . , 318 '.' '.' . ' . .:. ' , ., . , . , , . , , 318

15.3 Interior Iighting equipment: , 15,3.1 General ..·· ',' '.. ' <, , '.' " , , , 318

15.32 15.3.3 15.3.4 15.3.5 15.3.6

Location of lighting equipment : . , " ,:,.,. '. . , . ,. , .. , , .:.. ' .. .: .. , Installation. of lighting equipment : ,, Wiring of lighting. equipment. '.. , .. ; , .. , , ., .. Earthing of.Iighting equipment, : , " .' ;' ..•. ~, Electric-discharge lighting systems operating .at 1000V or less

15.4 . Outdoor lighting equipment ., . , , .. , .. , ,' . ','. .,. .,.,,, ,," .

,

. . , . 320

323

,., .. , 323

, , , . 326 .. , , 326

, , . , . 327

15..4.1 General /. ; .. '. .. " ... '.' .. ., , •.......' " . '.. , , , . , . : ' , . , , . , . 327

: . 328

. 15.4,2: Pennanent outdoor floodlighting instaliation ..... ' " ; .~ 1,5.4.3 Exposed ' wiring outdoor lighting ., .. , , , " 331

.' . forpermanent . ... Annex A (Normative) .' .. '. ' ;, , , ,

,

, .; , . ' .. ,

,

'. ' , 334

XIII

.

,

Section 16 Fire Alarm System and Fire. Pumps" 16.1 Scope, . '. " ., '...•...... " .. ' " .. ' 1'6.2 Normative references :

16:3 Definitious .. "

.

·

";.' '.,' '. ~

:' ,' ; .... ,

: ,"

:

.344 ,., 344

, .•.......... ', '. . : ~ .. " : " '. . '.' 344

16.4 Design consideration ~, ' '. . . ' ; .. ' 34( . 16.4.1 General ~ '. ' '~ . ", : ' .. '. 346' . . .- . ' . 16A.~·· Circuit design " ; : '. . ~4~. . 16.4.3 Manual points ., " ; .: ~ : '348 ' . 16Ao4 selection of fire detectors . -.:.. .'. . . .. .. . . . ~ . " . .. . '" •. :~'.' .: . 3~9'. 16:45 Sitting detectors' • .. ',' • . . . . . . . . . . . . . . . . . . ,. . . ',' . . . . 3Sq 16.4.6Sitting of heat' sensitive cPoint) detectors.....' .... '.... '. '. ~ 35i . 16.4.7 Vibration combined with rapid temperature change .. '.' .. " ~S3: . '1604.8 Sitting ofheat-sensitive.(line) detectors " . : ... '" .. , ',- . ; 354· . ',' 16.4.9 Si.tting of smoke-sensitive detecters .•......•. ; .. : ',' . .;: ~j:54 . . : ., : 3'54 16.4.10 Audible and visual alarms .. " .. ".. " .. , .. ;

can

,

of

165 Cables and'.wiring -."

16.5.t Cables, .

,

, .. ' ' .

1'6.5.2 Wiring method '

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.

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::. ~ "

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: ..• <3.5~: .

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; .,. " •...•.. 3;S~

" .. ,

.

I

16,6 EqUipment bonding . . .....- . .. . .. , . . . . .. . . .' . . .. . . .. . . . :, • .. . " : 3~S~ 1-6.6.1' Exposed. nea-esrreat carrying' metal p~' .. '. 16.6..2 Bonding conductor ; ,

p. •

•

•

"

•

•

•

•

"

•

•

•

.' • . •

35~

'...•.... 3~',

t€t 7. Power supply system . ., . ". .. . . .. .'- . . . . . '.. . . . . .. . . . . . . • " .. . . • . .' 3;~

16.7.1 .O.peratIDR voltage . . . 16.7'.2 Seurees.ofpower . ",,,' 1-6.7.3 Current supply."

Jist

.. . . .,~ .. . . . . . .." . . '.' . . ., . • . . . . " . , 3St ', ' , 36~'

16'.8; .Fire pumps ........',........... ~>. . • . .. . . .. . . .• •. .. . . , ".. . .. . 36.,¥

16.8..1 Conductors ..", . .. ... . . . . '.'. .> . . . . . . '" " . . . " . . . . . . . . . 36<~

16;8.2 Wiring method: ., .. . . .. . . . , . . ., . .. . , . . . . . , . . .. . . . 3'(i,~

16JtJ Consumers:' service &r fire pumps: . . . . . . . . . . . . . . . .. . . . . . . 16,f

16.8,4 Protection ~ ' ~ , .. , 36~

Arln.e* A (Informative). . . . '. . .. , . . ., . . . . .. . . . .,.. . . . . J6?~

.' Annex B (Informative): . .. . . . . . . . .. ", . , . .. . .. . . . . . . . . '" . . , . . .. . . 36~

XIV

S&ti()n '.t';" S~gns and Outline Lighting . '. . 17.1 ".Scope . . .. . . . . . . . . • '. ~. . . . . .. .. .. . . . " ; . . . . . . .' 1 i2 Normative references ' : ' 17.3 General requirements ' ,. ' . 17 :3.1. Construction

11.3.2. Disconnecting means 17.3.3 Rating of.disconnecting means and control devices '. . . 17.3.4 Thermal protection . . . .. ~ . . . . . . . . . '.. 17.3.5 Branch.circuit capacity 17.3.6 Location ~ ' ' ": .'" : 17.3.7 Bonding '.. ', , ; , i 7.3.8 Protection of sign leads . ., . . . . . . . . .'. . '. . .'. . . . . . . 17.3.9 Installationof conductors ' .. , . ' : .:: ' '.. ': : . : ~ 17.3.10 Fuseholders 'and flashers , .•.... '

. . . J71

'. . 371 .

" . 3.71 371

372

, .•. 3/2 .. . . . . . .. :3 72

; ·372 '.' .. :. 372

' ,' 373

.. . . . .;. . . . 373

: . 373

,. , . , 373

17.4 .High-voltage luminous discharge tube signs and outline Lighting ... '. ... 17.4.1 Enclosure .......,....... ..' .'. : . , :'. '. . ; . . "'" , . < ;' • '. • ; , • " .' .. '.... 17.4.2 Protection of uninsulated.part , : .•.... ~ . 17.4.3 Transformers ' , ~ . : .'.' ' :" 17.4.4High,:voltag~ wiring methods ', <. : .. '. , .. :.. ' , .. :.'.. '.

373

373

374

374

375

. Section '18 Lifts, Escalators and SiDiUar Eq~~IJment ,/

.

.

.

18.1 Scope ~'., : ','" : : '377 ' .. '•.' .. : ; ' ,. ' <.. 377 .. 18.2 Normative references .. , . '18.3 General .....,...,....... ~ .. ", '.' .' . . . . .~. .; .. .. ,'. . :.. . . 377 ' ' : 37'7 18.3.1 Voltage limitation •.... ~ : .' 18.3.2 Live parts enclosed. . ,' .. ; , 377

.' .: . '. . ~ 18,4 Conductors .. ' 18A.1 Installation of conductors', 18.4.2 Minimum size of conductors 18.4.3 Motor circuit conductors .18.5 Wiring ,.: 18.5.1 Wiring methods, .. , 18.5.2 Branch circuits for auxiliary systems

,

378

, 378

378

379

379

379

380

'XV

18.6 Installation of conductors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . '. . . 380

18.6.1 Number of conductors in raceway " : 380

18.6.2 Supports 380

18.6.3 Different systems in one raceway or travelling cable •......... 380

18.6.4 Wiring in hoistway : 381

18.6.5 "Electric equipment in garages and similar occupancies 381

18.6.6 Sidewalk lifts 381

18.7 Travelling cables ~., "18.7.1 Suspension 18.7.2 Hazardous J.classified) location 18.7.3 Protection against damage 18.7.4 Installation 18.8 Disconnecting means and control 18.8.1 General 18.8.2 Type 18.8.3 Location 18.8.4 Phase protection

381

381

382

382

382

; ; : \. "

:

382

382

383

383

383

18.9 Overcurrent protection 383

1~.9.1 Control and operating circuits ............".............. 383

18.9.2 Motors 384

XVI

18.10

Machine room 18.10.1 Guarding equipment 18.10.2 Clearance around control panels and disconnecting means

384

384

384

18.11

Earthing. . . . . . . . . . . . . . . ". . . . . . . . . . ................. 18.11.1 Metal raceway attached to cars 18.11.2 Electric lifts 18.11.3 Non-electric lifts 18.11.4 Method of bonding ......"................;.........

384

384

385

385

385

18.12

Overspeed " .' 18.12.1 Overspeed protection 18;12.2 Motor-generator overspeed device

385

385

386

18.13

Emergency power 386

18.13.1 Supply ; 386

18.13.2 Disconnection 386

18.13.3 Hydraulic lifts disconnecting means . . . . . . . . . . . . . . . . . . . . . 386

---------_._------_._----

18.14

--- ----------

Machine rooms and hoistway pits lighting and Auxiliary . . . . . . . . . . . 386

386

18.14.1 Machine room .. '.' 18.14.2 Hoist pits 387

Section . 19 Theatre Installation 19.1 19.2 19.3 19.4

Scope Normative references , Wiring method Fixed stage switchboard ~ 19.4.1 Fuses 19.4.2 Overcurrent protection ; 19.4.3 Dimmers 19.4.4 Control of stage and gallery pockets 1904.5 Conductors

; 388

388

388

389

389

389

, 390

390

390

: :

19.5 Portable switchboard on stage 19.5.1 Construction of portable switchboards 19.5.2 Supply for portable switchboard ~ ' 19.6 Fixed stage equipment 19.6.1 Footlights ' 19.6.2 Metal work ; 19.6.3 Clearance at terminals 19.6.4 Mechanical protection of lamps in borders, etc. . 19.6.5 Suspended fixtures 19.6.6 Connections at lampholders '.' ~ 19.6.7 Ventilation .for mogullampholers 19.6.8 Conductor insulation for field-assembled fixtures 19.6.9 Branch circuit overcurrent protection 19.6.10 Pendant lights rated more than lOOW 19.6.11 Cables for border lights ~ 19.6.12 Wiring to are pockets 19.6.13 Socket outlets and plugs 19.6.14 Curtain motors 19.6.15 Flue damper control

19.7 Portable stage equipment 19.7.1 Fixtures on scenery '.' 19.7.2 String or festooned lights 19.7.3 Flexible conductors from portable equipment 19.7.4 Portable equipment fo~ 'stage effects

391

391

391

'

' ,

;

'.'

391

391

391

392

392

, . 392

392

392

392

392

393

393

393

393

394

394

394

394

395

395

, . 395

XVII

-----_._--_._-_.

------------

------_._._--_

.

Section 20 Emergency Systems, Unit Equipment, and Exit Signs 20.1 Scope 20.2 Nonnative reference 20.3 General 20.3.1 Adequate capacity 20.3.2 Instruction 20.3.3 Batteries maintenance 20.3.4 Lamps ; 20.3.5 Circuits 20.3.6 Method of wiring

'

,

,

396

396

396

396

, 397

397

397

397

397

20.4 Emergency systems 20.4.1 Supply 20.4.2 Control 20.4.3 Overcurrent protection 20.4.4 Audible 3.Q.d visual trouble-signal devices

398

398

398

398

398

20.5 . Unit equipment ~ .. 20.5.1 Mounting 20.5.2 Supply connections

399

399

400

~

20.6 Exit signs 20.6.1 Power supply 20.6.2 Wiring

401

40 I

401

Section 21 Motion Picture Studios, Projection Rooms, Film Exchanges and Factory 21.1 Scope 21.2 Nonnative references 21.3 General .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.3.1 Wiring method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.4 Viewing, cutting and patching table fixture 21.5 Film-vaults and storage rooms 21.5.1 Equipment in film vaults and storage rooms 21.5.2 Wiring method in film-vaults 21.5.3 Lighting fixtures in film-vaults 21.5.4 Film-vault circuits

XVIII

402

402

. 402

. 402

403

403

403

403

403

404

21.6 Motion picture projection rooms.. . , .. . . . . . . . . . 21.6.1 Lamps in projection rooms 21.6.2 Arc lamp current supply 21.6.3 Ventilation 21.7 Motors and generators

. . . .. . . . . . . .. 404

; 404

" 404

404

. . . . . . . . . . . . . . . . . . . . ~ . . 404

. Section 22 Diagnostic Imaging Installation 22.1 Scope .. '. . . . . . . . . . . . . . . . . . . . '.' 22.2 Nonnative references '..•.. " 2'2.3 Defmitions.....................................:....... 22.4 High-voltage guarding ...........................•......... ',' 22.5 Connections to supply circuit 22.6 Disconnecting means 22.7 Transformers and capacitors '.' . . . . . ~.. . . . . . . . . ; . . . . . . . . . . . . . 22.8 Control 22.9 Ainpacity of supply conductors and rating of overcurrent protection Bonding. . . . . . . . . . . . . . . . . . . . . . . . . . .' . . . . . . . . . " . . . . . . 22.10

405

405

405

406

406

406

407

407

408

408

Section 23 Electrical Communication Systems 23.1 Scope ' 23;4 Nonnative reference ...................•.................. 23.3 General 23.3.1' Circuits in communication cables 23.3.2 Hazardous locations '. . . . . . . . . . . . . . . . . . . . . . 23.3.3 Approved transformers . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . .

409

409

409

409

410

410

23.4 Inside conductors ~ . . . . . . . . 410

23.4.1 Conductors arrangement ; 410

23.4.2 Insulation . . . . ..410

,. 410

23.4.3 Earthing conductors with an outer metal covering 23.4.4 Separation from other conductors : : 410

411

23.4.5· Penetration of a fire separation 23.4.6 Communication cable in hoistways 411

23.4.7 Communication conductors in ducts and plenum chambers 4J2 23.4.8 Data processing systems 412

23.4.9 Conductors under raised floors _ - 412 23.4.10 Conductors in concealed installations 412

23.4.11 Type CFC under-carpet wiring system -413

XIX

- - - - - -_ ....

_0_'

__ ..

23.5 Equipment 414

23.5.1 Communication equipment in bathrooms 414

23.5.2 Equipment in air ducts, plenums, or suspended ceilings 414

23.5.3 Exposed equipment and terminations ; 415

23.5.4 Earth circuits . . . " . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . : . . 415

23.5.5 Communication systems in hospitals 415

23.6 Outside conductors 23.6.1 Overhead conductors on poles 23.6.2 Overhead conductors on roofs 23.6.3 Lightning conductors 23.6.4 Swimming pools 23.7 Underground circuits 23.7.1 Direct buried systems 23.7.2 Underground raceway

.: ~

'

; :

.: :

415

~15 415

416 .

416 .

416

". s . 416

417

I

23.8' Earthing .....................................;........ '.. 417

23;8.1 Bonding of cable sheath. ." : .. : ...•.... 417

. 23.8.2 Cable-sheath bonding conductor :. :. ~ .. " 418

23.8.3 Earthing electrode .'.. 418

23.8.4 Earthing electrode connection 419

'.: : 419

23.8.5 Bondingof electrodes

.Section ,24..Community Antenna Installation For Radio And television Reception ".24.1 .Scope : :.~ 24.2 Nonnative references.: 24.3 Technical requirements ' . ': .' 24.3.1 Mechanical .•.......................... : 24.3.2 Electrical

'.'

420. 420

421

421

421

24.4 Equipment .. ; '" 421

24.4.1 Community antenna distribution amplifiers and other power sources . 421

24.4.2 Exposed equipment and terminations 422

422

24.4.3 Equipment earthing ~ 24.5 Community antenna distribution network 24.5.1 Conductor 24.5.2 Voltage limitation 24.5.3 Hazardous locations

xx

:

'

422

422 :422 423

24.5.4 24.5.5 24.5.6 24.5.7 24.5.8

Supports Earthing of outer conductive shield'~f a coaxial cable Earthing conductor Earthing electrode Earthing electrode connection

423

423

423

424 .

424

~ , 'i ; ~ " . .: 42~ 24.6 Conductors within buildings ~ 24.6.1 Separation from other.conductors, ; .. , . ,:.424 -.,.. , 425

24.6.2 Conductors in it vertical.shaft.. . ; .: .. , .. : .. , 24.6.3'Penetration of a fire separation : .' .. ~ .•........ ' 426

24.6.4 Community an~a distribution co~ductors inducts and plenum C~bers" .. 426' ',' ",>, ' • • ~ ••• ' " .426

24.6.5 Raceways " '. . '"

24.7 'Conductors outside of buildings ' : ~ •.... 426

; ; '.' :. ' '. : '. ~ 426 ' 24.7.1 Overhead conductors on poles .. ~ 24.7.2 Overhead conductors. on roofs.,' . ' . . ". . . " 426

. 24.7.3 Conductors on buildings ..........;.......... ..:. . " " . . 426'

24.7.4 Conductors entering buildings " ~ -. 427

24.7.5 Swimming pools , ~ " ................• ; .. :.. " '.. ; . ~ ., 427,

I

.

24.8 Underground conductors ,.,. 24.8.1 Direct buried systems .' .. ' ,. ~ 24.8.2 Underground raceway : '. 24.8.3 . Underground black d1stributio~. 24.9 Lightning arresters for ~eceiving stations 24.9.1 Lightning arrester 24.9.2 Earthing conductor ,24.9.3 Earthing electrode

.

'.' " : .. ,••.... ' '., .. ~ '. ' . '. ~.' , . .

:

427

427

428

429

429

429

429

430

. Annex A (Informative) . . . . . . . . . . . . . . . . . . . . .'. . . . . . . . . . . . . . . . . . . . 431

. Section 2S Swimming Pools" Fountains and Similar Installations 25.1 25.2 25.3 25.4

Scope ' ' Nonnative reference Definitions...........................................·.. General ' 25.4.1 Equipment installation 25.4.2 Overhead wiring ; 25.4.3 Underground wiring

446

446

446

447

447

448

448

XXI

SECTION

1

SCOPE AND DEFINITIONS

1.1

SCOPE

(1) This Code applies to the design, selection, erection, inspection and testing of electrical installations for residential, commercial, public and industrial premises including prefabricated buildings, construction sites, exhibitions, fairs and other temporary installations up to and including 1000.0V a.c. or 1500.0V d.c.

(2) This Code does not apply to: a) b) c) d) e) f) /'

~)

h) i) j) .

1.2

electric traction equipment,

electrical equipment of automobiles,

electrical equipment on board ships,

electrical equipment in aircraft,

public street-lighting installations,

installations in mines,

radio interference suppression equipment, except so far as it affects safety of the installation, fixed wiring for telecommunication, signalling, control and the like, internal wiring.of apparatus, systems for distribution of energy ,to the public, or power generation and transmission for such systems.

NORMATIVE REFERENCES

(1) The following references contain provisions which, through reference in this text, constitute provisions of the Ethiopian Building Code Standards on Electrical Installation of Buildings.

a) IEC 364-1:1972 Electrical Installations of Building, Part 1, Scope, Object and Definitions.

1

EBCS-10 1995

ETHIOPIAN BUILDING CODE STANDARD

-------~~--------------


cabinet

an enclosure of adequate mechanical strength, composed entirely of noncombustible and absorption-resistant material, designed either for surface or flush mounting, and provided with a frame, mat, or trim, in which swinging doors are hung.

cable bracket

a horizontal cable support system, consisting of elements fixed at one end only, spaced at intervals along the length of the cable and on which the cable rests.

cable channel

an enclosure situated above or in the ground, ventilated or closed, and having dimensions which do not permit the access of persons but allow access to the conductors and/or cables throughout their length during and after installation. A cable channel mayor may not form part of the building construction.

cable cleat

a component of a support system, which consists of elements spaced at intervals along the length of the cable or conduit.

cable coupler

a means of enabling the connection or disconnection, at will, of two flexible cables. It consists of a connector and a plug.

cable ducting

a manufactured enclosure of metal or insulating material, other than conduit or cable trunking, intended for the protection of cables which are drawn-in after erection of the ducting..

cable ladder

a cable support consisting of a series of supporting elements rigidly fixed to main supporting members. The supporting elements occupy less than 10% of the plan area.

cable tray

a cable support consisting of a continuous base with raised edges and no covering. A cable tray is considered to be non-perforated, where less than 30% of the material is removed from the base.

cable trunking

a manufactured enclosure for the protection of cables, normally of rectangular cross-section, of which one side is removable or hinged.

4

EBCS-10 1995


SECTION 1: SCOPE AND DEFINITIONS

cable tunnel

an enclosure (corridor) containing supporting structures for conductors and/or cables and joints and whose dimensions allow persons to pass freely throughout the entire length.

cartridge fuse link

a device comprising a fuse element or several fuse elements connected in parallel enclosed in a cartridge usually filled with arc-extinguishing medium and connected to terminations. See fuse link.

circuit

an assembly of electrical equipment supplied from the same origin and protected against overcurrent by the same protective dcvicc(s).

circuit-breaker

a device capable of making, carrying and breaking normal load currents and also making and automatically breaking, under predetermined conditions, abnormal currents such as short-circuit currents. It is usually required to operate infrequently although some types are suitable for frequent operation.

circuit-breaker (linked)

a circuit-breaker the contacts of which are so arranged as to make or break all poles simultaneously or in a definite sequence.

circuit protective conductor (CPC)

a protective conductor connecting exposed conductive parts of equipment to the main earthling terminal.

Class I equipment

equipment in which protection against electric shock does not rely on basic insulation only, but which includes means for the connection of exposed conductive parts to a protective conductor in the fixed wiring of the installation.


EBCS-10 1995

5


equipotential bonding

electrical connection maintaining various exposed-conductive-parts at substantially the same.potential.

equipotential zone (see earthen. equipotential zone). exposed-conductive-part

a conductive part of equipment which can be touched and which is not a live part but which may become live under fault conditions.

externallnjluence

any influence external to an electrical installation which affects the design and safe operation of that installation.

extraneous-conductive-part a conductive part liable to introduce a potential, •generally earth potential, and not forming part of the electrical installation. fault

a circuit condition in which current flows through anabnonnal or unintended path. This may resultfrom an insulation failure or the bridging of insulation. Conventionally the impedance between live conductors or between live conductors and exposed or extraneous conductive-parts at the fault position is considered negligible.

fault current

a current resulting' from a fault.

feeder

a conductor or group of conductors that transmit electrical energy from a service supply; transformer, switchboard; distribution centre, 'generator, or other source of supply to branch circuit overcurrent device.

final circuit

a circuit connected directly to current-using equipment, or to a socket-outlet or socket-outlets or other outlet points for the connection of such equipment.

fixed equipment

equipment fastened to a support or otherwise secured in specific location.

flexible wiring system

a wiring system designed to provide mechanical flexibility in use without degradation of the electrical components.

10

EBCS-10 1995


SECTlON 1: SCOPE ANO DEFlNITIONS

functional eartlling'\

'. connection to earth necessary for proper functioning of electrical equipment: 4

jimetJontJI extra-low vo1Jllge

any extra-low voltage system in which not all of the protective measures required for SELV have been applied.

fuse

a device that by the fusing of one or more of its specially designed and proportioned components, opens the circuit in which it is inserted by breaking the' current when this exceeds a given value for a sufficient time. The fuse comprises all the parts that form the complete device.

fuse element

a part of a fuse designed to melt when the fuse operates.

fuse link

a part of a fuse, including the fuse element(s), which requires replacement by a new or renewable fuse link after the fuse has operated and before the fuse is put back,into service.

1I0tair sauna

a room or location in which air is heated to a high temperature and in which the relative humidity is normally low, rising for short periods of time only when water is poured over the heater.

indirect contact

contact of persons or livestock with exposed-conductive-parts made live by a fault and which may result in electric shock.'

installation (abbr., see electrical installation). insulation

suitable non-conductive material enclosing, surrounding, or supporting a conductor.

isolation

a function intended to cut off for reasons of safety the supply from all, or a discrete section, of the installation by separating the installation or section from every source of electrical energy.

,isoilltor

a mechanical switching device which provides the function of isolation.

ladder (see cable ladder)


EBCS-10 1995

11,

ELECTRiCAL INSTALLATION OF BUILDINGS

live part

a conductor or conductive part intended to be energised in normal use, including a neutral conductor.

luminaire

~quipment which distributes, filters, or transforms the

light from one or more lamps, and which includes any parts necessary for supporting, fixing and protecting the lamps, but not the lamps themselves, and where necessary, circuit auxiliaries together with the means for connecting them to the supply. For the purpose of the regulations a lamp holder, however, supported is deemed to be a luminaire. luminaire supporting coupler (LSC)

a means, comprising an LSC outlet and an LSC plug, providing mechanical support for. a luminaire and the electrical connection to and disconnection from a fixed wiring installation.

LV switchgear and control gear assembly

a combination of one or more low-voltage switching devices together with associated control, measuring signalling protective, regulating equipment, etc., completely assembled under the responsibility of the manufacturer with all the internal electrical and mechanical interconnection and structural parts. The components of the assembly may be electro mechanical or electronic. The assembly may be either type-tested or partially type-tested.

main earthing terminal

the terminal or bar provided for the connection of protective conductors, including equipotential bonding conductors, and conductors for functional earthing if any, to the means of earthing.

mechanical maintenance

the replacement, refurbishment or cleaning of lamps and non-electrical parts of equipment, plant and machinery.

1,2

EBCS-10 1995


-I----~·_------'----------------'---~----'---~

I

-I


neutral conductor

a conductor connected to the neutral point of a system and contributing' to the transmission of electrical energy. c.'

nominal voltage (see voltage, nominal). obstacle

a part preventing unintentional contact with live parts but not preventing deliberate contact.

origin of an installation

the position at which electrical energy is delivered to an electrical installation.

overcurrent

a current exceeding the rated value. For conductors the rated value is the current-carrying· capacity.

overcurrent detection

a method of establishing that the value of current in a circuit exceeds a predetermined value for a specified length of time.

overload current

an overcurrent occurring in a circuit which is electrically sound.

permit

the official written permission of the Authority having jurisdiction on a form provided for the purpose, authorizing work to be commenced on any electrical installation.

phase conductor

a conductor of an a.c. system for the transmission of electrical energy other than a neutral conductor. The term also means the equivalent conductor of a d.c. system unless otherwise specified in this Code.

plug

a device, provided with contact pins, which is intended to be attached to a flexible cable, and which can be engaged with a socket-outlet or with a connector.

point

a termination of the fixed wiring intended for the connection of current-using equipment.

portable equipment

electrical equipment which is moved while in operation or which can easily be moved from one place to another while connected to the supply.


EBCS-1 0 1995

13

---~------'--------'------'--'- - - - _ .


prospective fault current

the value of overcurrent at a given point in a circuit resulting from a fault of negligible impedance between live conductors having a difference of potential under normal operating conditions, or between a live' conductor and an exposed-conductive-part.

protective conductor

a conductor used for some measures of protection against electric shock and intended for connecting together any of the following parts (refer to Figure 1.1): (a) (b) (c) (d) (e)

exposed conductive parts extraneous conductive parts the main earthing terminal' earth electrodets) the earthen point of the source, or an artificial neutral.

raceway

an enclosed channel designed expressly for holding wires, cables, or busbars, with additional function as permitted in this Code.

reduced low voltage sysiem

a system in which the nominal phase to phase voltage does not exceed llO.OV ahd the nominal phase to earth 'voltage does not exceed 63.5V.

reinforced insulation

single insulation applied to live parts, which provides a degree of protection against electric shock equivalent to double insulation standard.

~

.14

EBCS-10 1995


~~------'~---

.


~

l

-1

M

,

1

....,

A

1

M

,

1

,

A

c

I

M

r<

1

B

,

p

Z

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3 ___

...t..)~

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~ " "" " '\ ~"'''

- _Figure 1.1 Example of -,earthing arrangeme..ts 1,2,3,4

_1 2

3 4

Protective conductors circuit protective conductor main equipotential bonding conductors earthing conductor supplementary equipotential bonding conductors(where required)

B M C

P T E

Main earthing terminal Exposed 'conductive part Extraneous conductive part Main metallic water pipe Earth electrode Other means of earthing

residual current

the vector sum of the instantaneous values of current flowing through all live conductors of a circuit at a point in the electrical installation.

residual current device

a mechanical switching device or association of devices intended to cause the opening of the contacts When the residual current attains a given value under specified conditions.

residual operating current residual current which causes the residual current device to operate under specified conditions.

ETHIOPJAN BUILDING CODE STANDARD

EBCS-10 1995

15


resistance area (for an earth electrode only)

the surface area of ground (around an earth electrode) on which a significant voltage gradient may exist.

restrictive conductive location

a location comprised mainly of metallic or conductive surrounding parts. within which it is likely that a person will come into contact through a substantial portion of his body with the conductive surrounding parts and where the possibility of preventing this contact is limited.

ring final circuit

a final circuit arranged in the form of a ring and connected to a single point of supply.

safety service

an electrical system for electrical equipment provided to protect or warn persons in the event of a hazard, or essential to their evacuation from a location.

SELV

an' extra-low voltage system which is electrically separated from Earth and from other systems in such a way that a single fault cannot give rise to the risk of electric shock.

service

the conductors and equipment for delivering energy from the electricity supply system to the wiring system of the premises served.

shock (see electric shock). shock current

a current passing through the body of a person or livestock such as to cause electric shock and having characteristics likely to cause dangerous effects.

short-circuit current

an overcurrent resulting from a fault of negligible impedance between live conductors having a difference in potential under normal operating conditions.

simultaneously accessible parts

conductors or conductive parts which can be touched simultaneously by a person or, in locations specifically intended for them, by livestock.

16

EBCS-10 1995


I I

S~CTION 1: SCOPE AND DEFINITIONS

Simultaneously accessible parts may be Live parts, exposed conductive-parts, extraneous-conductive-parts, protective· conductors, or earth electrodes. socket-outlet

a device, provided with female contacts, which is intended to be installed with the fixed wiring, and intended to receive a plug. A luminaire track system is not regarded as a socket-outlet system.

spur

a branch from a ring final circuit.

stationary equipment

electrical equipment which is either fixed, or equipment having a mass exceeding 18.0kg and not provided with a carrying handle.

supplementary insulation independent insulation applied in addition to basic insulation in order to provide protection against electric shock in the event of a failure of basic insulation. supply authority

any municipal corporation, commission, company or person supplying electrical power or energy intended for sale or distribution to the public.

switch

a mechanical device capable of making, carrying and breaking current under 'normal circuit conditions, which may· include specified operating overload conditions, and also of carrying for a specified time currents under specified abnormal circuit conditions such as those of short-circuit. It may also be capable of making, but not breaking, short-circuit currents.

switch, linked

a switch the contacts ofwhich are so arranged as to make or break all poles simultaneously or in a definite sequence.

switchboard

an assemblyof switchgearwith or without instruments, but the term does not apply to groups of local switches in fmal circuits.

switchgear

an assembly of main and auxiliary switching apparatus for operation, regulation, protection or other control of an electrical installation.


. EBCS-10 1995

17

---"~----~--~---'----~"


system"

an electrical system consisting of a single source of electrical energy and an installation. For the purpose of this 'Code, the .system adopted shall be IT system. A system having one point of the source of energy directly earthen, the-exposed-conductive-parts of the installation being connected to-earth electrodes electrically independent of the, earth electrodes ofthe-source, (see Figure 1.2).

temporary supply unit

an enclosure containing' equipment for the purpose of taking a temporary electrical supply safely from an item of street furniture.

trunking (see cable trunking). voltage, nominal

voltage by which an installation (or part of an installation) is designated. The following ranges ofnominal voltage (r.m.s, values for a.c.) are defined: extra-low: Normally not exceeding 50.0V ae, or 120.0V ripple free d.c., whether between conductors or to earth, low:

Normally exceeding extra-low voltage but not exceeding 1OOO.OVa.c. or 150G.OV d.c.between conductors," or600.0V a.c.or900.0V d.c, between conductors and earth.

The actual voltage of the installation may differ from the nominal value bya quantity within normal tolerance.

18

EBCS-l0 1995


SECTION l: SCOPE ,AND DEFINITIONS

SOURCEO"~

-Jo

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'INSTAUA~ ' "

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'NS'JALLATION

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PARTS ':r

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TT System

Jldltqgereducei1 i,(See ,reiluced,lowvtiltagesystem). 'lfiiring system.

an assembly made up .of-cableor cbusbarsand parts which secure and, -;if :necessary~ -enclcsethecable-orbusbars.

"

ETHIOPIAN-BlJII.:DINGCODESTANDARD

EBCSo;l'O -t995

,t9

.

SECTION

2

9ENERAL REQUIREMENTS

2.1

ADMINISTRATIVE

2.1.1 Authority for Rules (1) By virtue of the authority vested in the Authority having jurisdiction, this Code has been adopted and hereby orders and directs its 'observance.

2.1.2

Permit

(I) Electrical contractors or others responsible for the carrying out of the work shall obtain a permit from the Authority having jurisdiction before commencing work with respect to ' installation, alteration, repair, or extension of any electrical equipment.

2.1.3, Application for Inspection (1) An application for inspection shall be fixed withthe Authority having jurisdiction on a form provided by the latter at the time the permit is obtained:

2.1.4

Posting of Permit

(1) A copy of the permit shall be posted in a conspicuous place on the '~ite of the work and shall not be removed until the inspection is completed.

2.1.5

Notification Re-inspection

(I) The Authority having jurisdiction shall be notified in writing by the electrical contractor that ' work is ready for inspection at such time or times as will permit inspection being made before any work or portion thereof is commenced.

20

EBCS-10 1995


. SECTION 2: GENERAL REQUIREMENTS

2.1.6 Plans and Specifications (1) Plans and specifications in duplicate or in greater number if required by the Authority having jurisdiction one copy to be retained by the Authority, shall be submitted by the owner or his agent to, and acceptance obtained from; the Authority before work is commenced on: a) wiring installations of public buildings, industrial establishments, factories, and other buildings in which public safety is involved: b) large light and power installations and the installation or apparatus such as generators, transformers, switchboards, large storage batteries: c) such other installations as may be prescribed by the Authority having jurisdiction.

2.1.7 Connection Authorization (1) Where any electrical installation or part thereof to which electrical power or energy has not

. previously been supplied is made in or upon any land building or premises, where any electrical

Installation or part thereof has been disconnected or cut off from any service or other source of

. supply under this Code, no supply authority, contractor or other person shall connect or re connect the installation or part thereof to any service or other source of supply unless: a) the installation and all work in respect thereof have been inspected by an inspector; and b) a connection authorization has been issued by the Authority having jurisdiction in respect of the installation.

2.1.8 Re-inspection (1) The Authority having jurisdiction reserves the right to re-inspect at any time electrical installation notwithstanding any previous inspection and acceptance, if and when it considers such action to be necessary.

2.1.9 Renovation of Existing Installation (1) The Authority having jurisdiction may require such changes as may be necessary to be made to existing installations where, through hard usage, wear and tear, or as a result of alteration or extensions, dangerous conditions have developed.


EBCS-10 1995

21

ELECTRICALINSTALLATION OF BUILDINGS

2.1.10 Use of Approved Equ"lpment (1) No one shall use any electrical equipmentother than approved electrical equipment ofa kind or type and rating approved for the specificpurpose fotwhich it is to be employed. 2.1.11 Deviaobilbr Postponement

(1) In any case where deviation or postponement of this Code maybe necessaIy,special pmnissiotl 'shallbe obtained befort, proceeding with the work, but this special permission shall apply only to the particular installation for which it is given. 2.1.12 Powers of Rejection (1) Even though approval has previously been granted, the Authority having jurisdiction may reject, 'at any time,anyelectrical equipmentunder any of the following conditions: a) If theequipment is substandard with respect to the sample' on which approval was granted. b) If the coaditions of use indicate thatth'e equipmerit:i'sflet suitable. 'c) If the terms ofthe approval agreement are not being carried.out, 2.1.13 lnstallatibn of Electrical EqQ.ipment (1) Electrical equipment shall be installed as to ensure that,after installation, ,there is ready access to nameplates and access to parts requiting maintenance.

2.1.14 Damage and Interference (1) No person shall interfere with any electrical installation or component thereof except when, I'll the course of alterations or repairs to non-electrical-equipment or structures, it maybe necessary to disconnect or move components of an electrical installations. (2) It shall be the responsibility ofthe .pers.~anying out thealteratiens or repairs to ensure tha~ the electrical installation is restored to 'a safe operating condition 'as soon as the progress ofthe alterations or repair will permit.

22EBCS~10

1,995

ETHIOPIAN 'BUILDING CODE STANDAlitp

I--------~

---

I SECTION 2: GENERAL REQUIREMENTS

2.2

TECHNICAL

2.2.1 Conventional Symbol$ (1) Graphical symbols that are to be used in all dmwings, wiring plans, etc for electrical installations of buildings shall be as indicated in Section 26 of this Code.

2.2.2 Coordination (1) Proper coordination and' collaboration between th~ architect, building engineer and the electrical engineer shall be effected from the planning stage of the installation.

(2) The provisions that will be needed. for tI:k accommodation of substation, transformer, switch room, lift wells and other appurtenant rooms, service cable ducts, rising mains and distribution cables, sub-distribution boards, openings and chases in floor and walls for all required electrical installation, etc, shall be specified in advance.

2.2.3 .Location and Requirement of Substation (1) The ideal location of an electrical substation for a group of buildings would be at the load

centre and shall be located on the ground floor.

(2) In multi-storeyed buildings, the substation shall preferably be installed on the lowest floor level, but direct access from the street for installation or removal of the equipment shall be provided. The floor level of the substation or switch room shall he above the highest flood level of the locality. In this case, the load centre would be somewhere between the geometrical centre and the air-conditioning plant room. (3) The availability of power lines nearby may also be kept in view while deciding the location of the substation.

2.2.4 Rooms (Spaces) Required (1) In allocating area of a substation, it shall be noted that the flow of electric power is from supply company's room to high tension room, then to transformer and finally to the low voltage switchgear room. The layout of rooms shall be in accordance with this flow.

ETHIOPIAN ,BUILDING CODE STANDARD

EBCS-10 1995

23

EL.ECTRICAL INSTALLATION OF BUILDINGS

(2) The following rooms are required in a substation: a) Switchgear Room - Supply iompany's switchgear room and/or space for meters. b) Transformer Rooms - The number and size of transformer rooms shall be ascertained from the total power requirement,of the consumer. c) Low-Voltage Switch Rooms - The floor area requirement in respect of low voltage switchgear room shall be ascertained from the number of feeders. «;I) Stand-by Generators. A room space not.less than 6.0m x 9.0m may be provided for housing a stand-by generator. e) Location' of Switch Rooms - In large installations other than where a substation is provided! a separate switch room shall be provided; this shall be located as closely as possible to the electrical load centre and suitable ducts shall be laid with minimum number of bends from the point of entry of the supply to the position of the main switchgear. The switch room shall also be placed in such a position that rising ducts may readily be provided therefrom to the upper floors of the building in one straight vertical run. In larger buildings, more than one rising duet and horizontal ducts may also be required for running cable from the switch room to the foot of each rising main. Such cable duets shall be reserved for the electrical services only which may, however, include medium and low voltage installation, such as call-bell systems; telephone installations should be suitably segregated. \

2.2.5

Location and Requirements of Distribution Boards

(l) The electrical control gear distribution boards and other apparatus, which 'are required on each floor may conveniently be mounted adjacent to the rising mains, and adequate space should be provided at each floor for this purpose.

2.2.6

Location and Requirements of PBXlPABX Rooms

(I) Information regarding provision for and location of PBXIPABX shall be obtained from the relevant authority and adequate space should be provided for installation of the boards.

24

EBCS-10 1995


SECTION 2: GENERAL REQUIREMENTS

2.3

PLANNING AND DESIGNING

2.3.1

General

(1) The design and planning of an electrical installation shall take into account all the prevailing conditions which may include some or all of the following: Type of supply. Envisaged load having regard to the requirements of the owner or occupant. The probable modifications and future extensions. The degree of electrical and mechanical protection necessary. The probable operation and maintenance cost taking into account the electricity supply tariffs available. f) The relative cost of various alternative methods. g) The need for radio and telecommunication interference abatement.

a) b) c) d) e)

2.3.2 Layout and Installation Drawing (1) The electrical layout should be considered after proper locations of all outlets for lamps, fans, appliances - both fixed and transportable, motors, etc, have been selected and best methods of wiring determined.

(2) All runs of wiring and exact positions of all points of switch-boxes and other outlets shall be first marked on the plans of the building and approved by the engineer in charge or the owner before the actual commencement of the work.

2.3.3 Design (1) The design of electrical installation shall ensure:

a) the protection of persons, livestock and property;

b) the proper functioning of the electrical installation for the intended use.

(2) The information required as a basis for design shall be: a) nature of current: a,c, and/or d.c.


EBCS-10 1995

25

ELECTRICAL INSTALLATION .OF BUILDINGS

b) nature and number of conductors: i) for a.c.: - phase conductor(s); - neutral conductor; - protective conductor.. ii) for d.c.: - conductors equivalent tothose listed above.

c) d) e) t) g) h) i)

voltage and voltage tolerances; frequency and frequency tolerance; maximum current allowable; prospective short-circuit current; nature of demand; emergency supply or supplies; environmental conditions.

(3) The design shall comply with the requirements of this Code.

2.4 MARKING OF EQUIPMENT 2.4.1

General

(I) Each piece of electrical equipment shall bear such of the following markings as may be necessary to identify the equipment and ensure that it is suitable for the particular installation: a) b) c) d) e) t) g) h) i)

j) k) I) m)

26

The maker's name, trademark, or other recognized symbol of identification.. Catalogue number or type. Voltage. Rated load amperes. Watts, volt-amperes, or horsepower. Whether for a.c., d.c., or both. Number of phases. Frequency in Hertz. Rated load speed in revolution per minute. Designation of terminals. Whether for continuous or intermittent duty. Evidence of approval. Such other marking as may be necessary to ensure safe and proper operation.

EBCS·10 1995


'SECTION 2: GENERAL REQUlREMEN,TS

(2) Each service box, at the time of installation, shall be marked in a conspicuous, legible. and permanent manner to indicate clearly the maximum rating of the overcurrent device which may .be used for this installation. (3) At each distribution point, circuit breakers, fuses, and switches shall be marked, adjacent thereto, in a conspicuous and legible manner to indicate clearly:

a) which installation or portion of installation they protect,or control;

b) the maximum rating of overcurrent device ,that is permitted, ,

2.4.2

Workmanship and Materials

(l) Careful attention shall be paid to the mechanical execution of the work in connection with any electrical installation.

(2) Any installation that has been badly arranged or poorly executed, either generally or in any particular way, will not be accepted by the Authority having jurisdiction.

2.4.3

Material for Anchoring to Masonry and Concrete

(1) Wood or other similar materials shall not be used as an anchor into masonry or concrete for the support of any electrical equipment.

2.4.4

Protection of Persons and Property

(1) Electrical equipment shall be installed and guarded so that adequate provision is made for the safety of persons and property and for the protection of the electrical equipment from mechanical or other injury to which it is liable to be exposed.

2.4.5

Maintainability

(1) An assessment shall be made of the frequency and quality of maintenance the installation can reasonably be expected to receive during its intended life. (2) Where an authority is to be responsible for the operation of the installation, that authority shall be consulted.


EBCS-10 1995

27


(3) The following characteristics are to be taken into account in applying the requirements of this Code, having regard to the frequency and quality of maintenance expected: a) Any periodic inspection and testing and maintenance and repairs likely to be necessary during the intended .life can be readily and safely carried o~t. b) The effectiveness of the protective measures for safety during the intended life is ensured. c) The reliability of equipment for proper functioning of the installation is appropriate to . the intended life.

.2~4.6

Enclosures

(1) Degree of protection provided by enclosures for electrical equipment shall be in accordance with IEC 529.

28

EBCS-10 1995


(

SECTION

3

ILLUMINATION "(1_

3.1

SCOPE

(1) This Section of the Code gives guidance on design and installation of artificial lighting systems in interiors; it also applies to artificial lighting of outdoor areas.

3.2



(a) BS 8206: 1985

Part 1 - Lighting for Building.

(b) DIN 5035:1990

Part 1 - Artificial Lighting, Terminology and General Requirements.

(c) DIN 5035:1990

Part 2 - Artificial Lighting, Recommended Values fdr Lighting Parameters for Indoor and Outdoor Workplaces.

(d) DIN 5035:1988

Part

(e) DIN 5035:1983

Part 4 - Artificial Lighting ofInteriors, Special Recommendations for Lighting Educational establishments

(f) DIN 5035:1987

Part 5 - Artificial Lighting ofInteriors, Emergency Lighting.

~

- Artificial Lighting of Interiors, Hospital Lighting.

(g) DIN 5035:1988 Part 7 - Artificial Lighting ofInteriors, Lighting of Rooms with VDU Workstation or VDU Assisted Workplaces.


EBCS-10 1995

29

ELECTRICAL INSTALLATION OF BUfLOINGS 3.3

DEFINITIONS

(1) For the purpose ofthis Section of the Code, the following definitions shall apply in addition to the terms defined in Section 1.

mean illuminance (E)

the arithmetical mean of the illuminance in a room or in a room zone being defined as that area of a room in which the same type of activity is performed at a number of work-places or which is used for similar purposes.

rated illuminance (EJ

the nominal value of the mean illuminance that the lighting installation is-designed to illuminate.

Ught loss facto,. (V)

the ratio of the rated illuminance, En. to the design value of the mean illuminance of a lighting systeIh.

depreciation factor (P)

the reciprocal of the light loss factor.

reflectance (Pc)

the ratio of the luminous flux reflected from a surface to the luminous flux incident on it.

general lighting

the required average illuminance with a certain degree of uniformity over the total area; and is obtained by a regular arrangement of luminaries over the ceiling area (see Figure 3.1).

localized lighting

a non-uniform illuminance over the whole work area (see Figure 3.2).

local lighting

lighting for individual workplace in addition to the general lighting produced by placing luminaries close to the visual task and supplemented by a general lighting (see Figure 3.1).

30

EBCS-10 1995


----'----~---~--'------'---~~---~---------'-------'-"-------

SECTION 3: ttlUMlNATION

---.-

~-'--::::~-~_:::-::-:---,

-

1\

'/

\ I

1\

----.-.. 1\ 1\ '"

\ I '\

I

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...

,

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II

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Figure 3.1 Generat fighting "I

-. b)MtChid

1\ r. IV \ 1"

I

\

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F1gure3.3 Lacallighting

ETHrOPIANBUILD1NGCOOE STANDARD

1

l

i\ .1\

V \

r

I

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r

LoealizedLighting

EBCS.:1\() 1:995

31

8


glare

a condition in which vision is affected by an excessive luminance and/or excessive differences in luminance in the visual field (i.e; parts of this field are excessively bright). A distinction is made between:

Note:

disability glare, defined asglarecausing an actualphysiological reduction in visual capability (impaired, perception of contrasts and forms), and discomfort glare, defmed as glare considered solely in terms of its psychological effect on the occupant. Discomfort glare experienced by the occupantof a room increases withtime andleadsto premature fatigue and a reduction in performance, performance attitude, and well-being.

direct glare

a glare caused directly by luminance from luminaries of luminous ceilings.

reflected glare

glare and contrast reduction caused by reflection of high luminance from glossy surfaces.

Note:

The maindisturbances causedbysuchreflection are contrast reduction, and impaired accommodation and fusion.

colour appearance

Note:

the chromaticity of an illuminant and is generally expressed as the colour impression received when looking at a light source.

The colour of the light emitted by a near-white sources can be indicated by its correlated colour temperature (CCT). Each lamptypehasa specific CCTj but for practical use,they have beengrouped into three classes (see Table 3.1).

Table 3.1: Correlated colour temperature classes

Correlated colour temperature (CCl) -

CCT < 3300 3300 < CCT < 5300 5300 < CCT

32

EBCS-10 1995

~

.

CCT CI188 ..

..

-

--

~

_. --

Warm (White) - WW Intermediate (white) - NW Cool (daylight white)- TW

ETHIOPIAN BUII.DING CODE STANDARD

SECTION 3: ILLUMINATION.

colour rendering Note:

the relationship between the original colour of an object and the colour in which it is rendered by artificial lighting.

The ability of light source to render colours of suiface accurately can be conveniently quantified by' the crn general colour rendering index. This index is based on the accuracy with which a set oftest colour:are reproduced by the lam~t of interest relative to how they are reproduced by an appropriate standard light source, identical agreement being given a value of 100.0/.1:, Bach lamp trJIe has a , specitic cm general colour rendering index; but for practical usc they can be divided into a number of groups (see Table 3.2)

'Table 3.2 Colour relldering groups

Colour rendering groupe

CIE general colour rendering Index (AJ

1A

R. > 90

Wherever accurate colour matching is reqUired; e.g. colour printing inspection.

18

80'
Wherever accurate colour jUdgements are necessary and/or good colour rendering Is . essential to appearance; e.g. shops and other commercial premises.

2

60 < R;, <80

Typical applloatlon

Wherever moderatecolour rendering Isrequired. 3

40< R. < 60 Wherever colour rendering Is of little significance . but marked distortion of colour is acceptable.

4

20 < R. < 40 Wherever colour rendering li'01 no Importanceat all and markeddistortion of colour Is acceptable.

emergency lighting

lighting designed to become operative promptly ifthe power supply to normal artificial lighting fails.

safety lighting

an emergency lighting requked for reasons of safety (general safety, prevention of accidents).

t For tabular florescentlamps apparent colour and colour rendering charaoteristics, refer to Table 3.4.


EBCS-10 199.6

33

"

·E1.ECTR~CAL

'INSTALLATION OF BUU..DINGS

escape lighting

a specified minimum illuminance for emergency escape purposes, thus,permitting buildings and plant to be safely evacuated at any time during their utilization.

'qfety lighting for ptU1lcIIlIu 1uIzJmImuworjplm:a

.safety lighting designed to ensure that the work performed arsuch workplaces can be safely terminated in the manner required and the workplaces .themselves evacuated' without

danger. Note:

ParticulllfhllZllfduUll wurkplacesan:;those whic:h representan immediate rlsk·afaccldlmtor apotentlaJ source of danger to third parties 'if the supply to the ligbtingshould fail, raised platfortns, theatre stages.race-coursesand arenas counting as particularly 'hazardous·worlq;laces.

stIIIIdbyllgh·ting

an emergency lighting which caaassumethe function of normaiartificial lighting for.B limited period so as to enable nomul1 ,activities to continue.

,..nsetiIM

the interval :between a faillR in the 'powersuppty to-the 'normal artificial lighting and the provision ·of:therequired illuminance by the ,emergen~y lighting. .

!NItt!ildllrlltlono!opertdlon

the period oftime for which an emergency lighting system is designed too,perate.

Umltdllrfltlollofoperatloll

the mmimum ;period of time during which :anemergency >lightingsystem·shall :still :00 capBble·ofachiev~gth.em:inim.um itluminancespecified for the given 'application.

Note:

'Thisconceptapplies~pecificaUytobauery-Qperated~stems.

illS.qldlife

the duration ofian emergency lighting system 'fromthe;dateof its commissioning up to ,the point in time at "which it only achieves the limit duration of operation.

sa/etyll1minaries

'a 'luminBry'which ,ml?:Y 'or may 'not be provided .with "its 'own powersupply and whlchisused forsafe~ lighting.

34

"EBCS.;10 t995

EfHIOPIAN 'BUILDING ,CODE .STANDARD

_ _ _ _ _ 0.

0

0

~_

SECTION 3: ILLUMINATION

escape sign luminaries

standby lighting luminaries

3.4

a moulded luminaire bearing a graphical symbol to serve as an escape sign; it indicates and assist the identification of escape . route. a luminary which mayor may not be provided with its own power supply and which is used for standby lighting.

LIGHTING REQUIREMENTS .

3.4.1 D1umio~ote (1) Recommended illuminance for different types of interiors, tasks and workspaces given in Table 3.5 and Table 3.6 shall be taken as the recommended minimum values on which the design and assessment of lighting installations are to be based. (2) For indoor workplaces that are manned full-time, a minimum rated illuminance of 200.01x shall be provided unless other factors (such as nature of operation, physiological reasons) require different values. (3) (a) In interiors designed for permanent human occupation, a minimum rated illuminance of 100.Olx is required.

(b) If tasks are performed at fixed-location workplaces outdoors that correspond to tasks performed indoors (e.g. operation of wood-work machines), then a rated illuminance specified for such tasks in Table 3.5 for indoor workplaces shall be provided. (4) At no stages in the useful life of the lighting installation shall the mean illuminance.. E,

obtained at the workplaces be less than 0.8 times the value of the rated illuminance; at no single

workplace shall illuminance ever fall to less than 0.6 times the rated illuminance.

3.4.2 Lumlnance . (1) Reflectance in the working zone shall be planned so that the ratio between task luminance (inner field) and that of the surrounding of the task are no greater than approximately 3: 1. (2) Reflectance of from 0.2 to 0.5 are recommended for working surfaces such as bench and,

desk tops.


EBCS-10 1995

35


3.4.3

Glare

(1) Glare shall not be caused by lamps qr luniinaries (direct glare) nor by reflection of high luminance from glossy surface (reflected glare).

(2) Lamps with a high luminance (e.g. filament lamps and high discharge lamps) shall always be' shielded. (3) In case of luminaries for local workplaces lighting, a direct view of the lamps shall be' precluded by shielding or by arranging them in a suitable position..

3.4.4

Light Direction and Modelling

(1) Lighting 'shall be directed to produce an adequate degree of modelling shadow to enable objects and surface texture to be easily recognized. (2) Unduly hard shadows shall be avoided. If the ratio E, (cyllndricalj.E, (horizontal) at a hight of 1.20m above floor is not smaller than 0.3, unduly hard shadows can be avoided. (3) Deep shadows producing excessive luminance contrasts shall be avoided.

3.4.5

Colour Rendering

(1) For inspection and comparison of colours, the cm general colour rendering index R, shall not exceed 90 and the rated illuminance shall be 1000.Olx.

(2) Only lamps meeting the requirements of Colour Rendering Group 3 (or higher) shall be used for lighting interiors. (3) Safety colours, shall be duly recognizable as such.

36

. EBCS-10 1995



3.5

EMERGENCY LIGHTING REQUIREMENTS

3.5.1· Escape Lighting

3.5.1.1

Illunfinance

(1) The minimum illuminance of the safety lighting for escape routes shall be I.O/x. This requirement applies to the centre line of an escape route along a horizontal plane O.2m above floor level.

(2) The response time shall not exceed a maximum of 15.0sec. (3) The rated duration of operation shall at least equal to the time that will be specified by safety law to be enacted by the concerned government body. (4) The limit duration of operation shall be % (for 1.0hr) or % (for 3.0hr) ofthe rated duration. (5) Safety luminaries for escape routes shall be sited according to their luminance distribution so as to meet the requirements specified for safety lighting and in such a way that they cannot easily be rendered ineffective. (Principal locations for the sitting of safety luminaries are, thus, near the exits of escape routes and at points where it is necessary to emphasize the positions of potential hazards.)

3.5.2

3.5.2.1

Safety Lighting for Particular Hazardous Workplaces

Illunfinance

(1) The minimum illuminance for such workplaces shall be O.IEn (rated illuminance specified for the task and room of such workplaces in Table 3.5) but not less than 15.0/x.

(2) The minimum illuminance for platform and theatre stages shall be 3.0/x, and 15.0/x for arenas and race-courses.

3.5.2.2

Colour rendering

(1) The colour rendering shall at least be equivalent to Group 3 so as to ensure that safety colours remain recognizable as such.


EBCS-10 1995

37


3.5.2.3

Response time

(l) The response time of safety lighting shall not exceed a maximum of 6.5s. (2) In case of raised platform, theatre stages, arenas and race-courses, the maximum response time shall be 1.0s. 3.5.2.4

.. Rated duration of operation

(1) For workplaces, the lighting shall be effective for as long as the hazard subsists; with a minimum duration of 1.0min.

(2) For raised platform, theatre stages, race-courses and arenas, the rated duration of operation shall at least be equal to the duration required by law.

3.5.2.5

Siting of safety luminaries in hazardous workspaces

(1) Safety luminaries shall be sited so as to ensure that the required illuminance is provided over the entire area in which hazardous tasks are carried out. 3.5.3

Standby Lighting

(1) The requirements to bernet by standby lighting are analogous to those applying for normal artificial lighting. To enable normal activities to continue, a minimum illuminance of 10% of the rated illuminance value is generally required.

3.6

LIGHTING REQUIREMENTS FOR VARIOUS TYPES OF BUILDINGS

3.6.1

.

General

(l) The design objectives for lighting shall be to provide both good task visibility and a satisfactory visual environment. (2) (a) The lighting of workspaces shall ensure good visibility of the visual objects; (b) The lighting of workplaces shall also be conducive to concentration and performance attitudes, counteract premature fatigue and permit any potential hazards to be clearly recognized.

38

EBCS-10 1995

ETHIOPIAN BUILDING CODE STANDARD ..

!--------'--

-----=------.c

~~

__

.J

I SECTION 3: ILLUMINATION

3.6.2

Industrial Buildings

(1) In addition to the lighting required for specific tasks, ageneral illumination shall be provided to allow safe movement through the building at all material times. (2) Where critical colour .matching is to be done for a long period, a minimum illuminance of 1000.01x shall be provided.

3.6.3

Offices

(1) As indicated on rated illuminance tables, for general offices illuminance of SOO.O/x and for drawing offices illuminance of 7S0.01x shall be provided. (2) Where VDU (Visual Display Units) are used, the illuminance shall be restricted to SOO.Olx or less to minimize the high brightness reflection from the screen and' large luminance differences between screen, any source documents and the backgrounds against which these items are seen. (3) Where localized lighting is used, the ratio of illuminance between adjacent areas shall not be morethan 3: 1 with a minimum illuminance for 3lty continuously occupied area of 200.01x. (4) Where local lighting is used, the ratio of illuminance between task area and the surrounding. area shall not exceed 3: 1.

(S) A glare limiting index of 19 is appropriate for general office rooms and an index of 16 is desirable for drawing offices because of the more demanding nature of work. (6) Where daylight makes a substantial contribution, lamps with a CCT of 4000.0k or above should be used.

3.6.4

Hotels and Restaurants

(1) In dinningrooms and restaurants an illuminance of 100.0lx is recommended on a dinning table. (2) In lounge and public bars, an average illuminance of SO.O/x is recommended. (3) In kitchens and other service areas, a general illuminance of 300.0/x is recommended and working areas should have an illuminance of SOO.O/x.


EBCS-10 1995

39

----------

ELECTRICAL ~NSTALLATION OF BUILDINGS

(4) Escape lighting shall be provided for public rooms, staircases and corridors and provisions shall be made for emergency lighting and exit signs.

3.6.5 Educational Establishments (I) The wide range of activities carried. out in teaching and 'the variety of working media used create constant changes in visual tasks; due to this, special requirements, over and above those given in Clause 3.4.1, shall apply to the quality of the lighting in teaching rooms. This requirements are given in the following Clauses. -s

(2) The guideline values for illuminance, colour appearance, colour rendering group and quality of class of direct glare restriction given in Table 3.7 shall be applied in teaching spaces. (3) Should the relevant type of room or activity not be listed in Table 3.7, the values given for a similar, comparable room or activity shall be used mutatis mutandis. (4) The guideline values given in Tables 3.5 and 3.6 for workspaces shall apply to rooms which have the same visual requirements as comparable workplaces, as well as to general purpose and office-type rooms. (5) The main chalkboard in teaching rooms and demonstration desks in teaching rooms for special subjects shall be equipped with a: supplementary lighting system to increase the vertical illuminance.

3.6.6 Hospitals (1) The guideline values for hospital lighting set in Table 3.8 shall apply to all rooms and zones of a hospital. (2) The lighting of bedded areas shall be conducive to the well-being of the patient, while also -nabling examination or treatment to be carried out. . To achieve these goals: a) (i) the general lighting illuminance shall be IOO.Olx and shall not dazzle the patients or nursing staff. (ii) the mean luminance as perceived by the recumbent patients shall be limited to

IOOO.Ocdlm 2 while the luminance of the ceiling shall nowhere exceed 500.0cd/m 2 •

40

EBCS-1 0 1995



b) (i) Each bed shall be equipped with a rigidly mounted, adjustable luminaire, A rated illuminance of 300.0lx shall be achieved on the reading plane (see Figure 3.4). (ii) To avoid glare in multi-bed wards, the luminance of reading luminaries in the field

of· vision of other patients shall not exceed 1000.Ocd/m2• c) (i) For the examination and treatment of patients at.the bedside, a rated horizontal illuminance of 300.Olx, inclusive of the general lighting, shall be provided 0.15m above the longitudinal axis of the plane of the bed surface. (ii) At no point along the axis in (i) above shall the illuminance be less than 150.0lx.

(iii)

The uniformity ratio of illuminance Emin:E, shall here not be less than 1:2.

d) (i) Night watch lighting with illuminance of approximately 5.0lx shall be provided for keeping patients under observation during the night. . (ii) In wards occupied by infants, a rated illuminance of 20.0lx is recommended.

(3) (a) General lighting with a rated illuminance of 500.0lx and Group I colour rendering properties shall be.provided for examination and treatment. (b) In addition to the general lighting an illuminance of at least 1000.Olx is generally required at the site of examination. (4) (a) The lighting in operatin~ theatre shall always be designed in conjunction with the lighting of the operating theatre field. (b) In view of the illuminances of 20,000lx to 100,000.Olx required in the operating field, the surrounding lighting shall be designed to reduce the adaptation problems which would be caused by extreme difference in the luminance between operating field and the surrounding area. (c) The illuminance of the surrounding light shall not be less than 1000.Olx at a height of 1.0m above floor level. (5) (a) Standby lighting system shall be provided forthe operating theatres, anaesthetic rooms, sterilizing sinks and recovery rooms.


EBCS-10 1995

41


(b) The standby lighting of the -operating table should be equal in all respects to the normal lighting of this area, and should be of the maintained type to ensuiJ!' continuous illumination. ,

;'~~

800

900

~

..

_ --

.. ..

Reading plane '

Examination plane Plane "0--1 . sur .Bce -,

be~

... o

C>

o

,o

~

CIO

Figure 3.4 Reference plans of a hospital bed

OUTDOOR LIGHTING REQUIREMENTS

3.7 3.7.1

Illuminance

(1) For outdoor workspaces, circulation areas/zones and work roads, the recommended rated illuminances in Table 3.6 shall be provided and they are to be taken as the recommended minimum values. (2) If the type of application of interest to the user is not listed, the recommended values specified for a similar space shall be applied analogously. 3.7.2

Colour Rendering Group

(1) At fixed location workspaces, the colour rendering capability shall at . least meet the requirements of Group 3t ; safety colours and colours used for classification purposes shall be recognizable as such.

t

42

Data on the group to which lamps belong with respect to their colour rendering capability are given in product lists of manufacturers.

EBCS-1 0 1995


~---~-------~-----'------------~--'-----------_-----':~----~--


3.7.3

Limitation of Glare

(1) Limitation of direct glare shall be based on Clause 3.4.3 of this Section. (2) If the outdoor workplace is floodlight, the luminaries used shall be so located and arranged that hazards due to direct glare are precluded. 3.7.4

Lighting of Outdoor Fixed Location Workspaces

(1) If -tasks art: performed at fixed location work spaces outdoors that correspond to tasks performed indoor, then, local wor~place lightings shall be provided .with rated illuminance equivalent to the values specified for such tasks in Table 3.5.


EBCS-10 1995

43

~ ~

Table 3.3 Typical characteristics of lighting sources used for general lighting Tungsten

Characteristics

Filament

II

Tungsten

I

halogen

I

. Low-pressure

High-pressure

sodium

sodium

Hot cathode

Cold cathode

High-pressure

tul;M.Jlar

tubular

mercury

fluorescent

fluorescent

fluorescent

I Mercury halide

Range of luminous efficac'~

(1.0 Im/W)

8to 18

18 to 24

100 to 175

65 to 120

35 to 90

40 to 60

35 to 55

65 to 85

25 to 1500

100 to 2000

10to 200

50 to 1000

4 to 125

20 W/mto 30

50 to 2000

250 to 10000

5000 to 10000

5000 to 10000

Available wattage range

fY'I)

W/m Range of nominal life

(h) Colour rendering group

1000 to 2000

2000 to 4000

6000 to 12000

1A

1A

Non existent

6000 to 12000

5000 to 10000

20r4

20000

3

I

depending on

I

lamp pressure

usec!.

I

I

Can very Widely depending on additives Manufacturers

should be consulted.

Need for control gear

No

No

Yes

Yes

Yes

Yes

Yes

Yes

Operating position

Any

Horizontal

Horizontal

Any

Any

. Any

Any

Scme restriction

Run-up time (min)

Immediate

Immediate

6 to 12

4 to 7

Immediate

Immediate

4

5

Restrike time (min)

Immediate

Immediate

3

1

Immediate

Immediate

25000 to 3000

28OOOt031oo

Not applicable

2200

2700 to 6500

2700 to 6500

CCl (K)

I

Note: Detailed information about any specific lamp type should be obtained from the manufacturer.

.:1

10 . 3600 to 4400

I

Table 3.4 Tubular fluorescent lamps apparent colour and colour rendering characteristics of lamps in general use Lamp name

Apparent colour

Colour rendering

(CCT class)

group

Cool

I

Colour rendering characteristics

Typical application

1A

Similar to northsky light; emphasizes blues and, to less extent, greens

Used where colour rendering similar to north sky daylight is needed

Cool

1A

similar to north light/colour matching but emits more ultraviolet to conform with natural sky light

Used where critical colour matching complying with

8S 95:Part 1 is required

Special

Intermediate

1A

Equal emphasis given to all colours

Triphosphor 4000

Intermediate

18

Emphasizes oranges, greens and blue-violets, subdues yellows and deep reds

Northlight colour matching Artificial daylight

.,"

i

I

I

Used where fine colour judgements are required, e.g. hospitals, art galleries and museums Factories. offices and shops where good, but not critical, colour rendering or matching is required together with high luminous efficacy

I

I

Triphosphor 3000

Warm

18

Emphasizes oranges, greens and blue-violets, subdues yellows and deep reds

Intermediate

I

I I

Intermediate

White

but not critical, colour rendering or matching is required

I together with high luminous efficacy

I

Cool white (natural)

Social areas, restaurants, hotels and homes Where good

2

3

significant proportion of daylight is admitted

Emphasizes yellows, and to less extent, greens;

Factories, offices and shops

Factories, offices and shops, particularly where a

shift towards violet Warm

Warm white

I

3

Emphasizes yellows and, to less extent, greens;

Commercial/public buildings

reds slightly subdued, blues subdued and shifted towards violet Warm

Lower-power compact lamps

~

VI

I

18

i

I

~

Emphasizes yellows and, to less extent, green and blues; red shifts slightly towards orange

subdues red and to some extent blues, which

I

I

I

I

Emphasizes oranges, greens blues and violets;

I Hotels, shops, homes; as a replacement for tungsten

subdues some yellows end deep reds

I filament lamps

~

0\

Table 3.5 Indoor workspaces recommended illuminance 1

Type of interior and/or task

2

3

Rated illuminance

Colour

4

5

Colour

Class of

rendering

direct glare

group

limitation·

En. in Ix

appearance

50

ww,nw

3

3

50

ww,nw

3

3

retrieval tasks

100

ww,nw

3

3

1.2.3 Warehouses with reading tasks

200

ww,nw

3

2

6

Remark

1 General spaces 1.1 Circulation zones in storerooms 1.2 Warehousing 1.2.1 Warehouses 10r goods of one kind or of large unit size 1.2.2 Warehouses with goods of different kinds and search and

1.3 Automatic high-bay store 1.3.1 Aisles and gangways

20

ww,nw

3

3

1.3.2 Control platform

200

ww,nw

2A

1

1.4 Despatch room

200

ww,nw

3

2

1.5 Rest rooms; sanitary facilities; medical rooms 1.5.1 Canteens

200

ww,nw

1

1.5.2 Other rooms for recreation and rest purposes 1.5.3 Rooms for gymnastic exercises

100

I

ww,nw

2A 2A 2A 2A 2A 2A

WW,nw

1A

ww,nw

300

ww,nw

1.5.4 Changing rooms

100

ww,nw

1.5.5 Washrooms

100

ww,nw

I

1.5.6 Toilets

100

1.5.7 Medical treatment and nursing rooms; first-aid facilities

500

I

I

I

Incandescent lamps may

1

be used when lighting is

1

to create a specific

2

atrnosphsre.

2

Supplementary mirror

2

lighting

1

optional

1.6 Building services installations 1.6.1 Machine rooms

100

ww,nw

3

3

1.6.2 Power supply and distribution

100

ww,nw

3

3

1.6.3 Telex and post rooms

500

ww,nw

2A

1

1.6.4 Telephone switchboard

300

ww,nw

2A

1

Table 3.5 Indoor workspaces recommended illuminance (conte'd) . 1


2

3

Rated illuminance,

Colour appearance

En' In .!! I

2 Circulation areas In bUildings 2.1 For persons

50

2.2 For persons and vehicles

100

l

4 Colour rendering group

5

Class of direct glare . limitation

6'

Remark

2.3 Stairs; escalators, and ramps

100

2.4 Loading platforms

100

lNW,nw lNW,nw lNW,nw lNW,nw

adjoining circulation areas

100

lNW,nw

3

3

where E n1 = En of the circulation areas.

2.6 Shed entrances

100

lNW,nw

3

3

En2 = En of adjoining

3

3

Adjustment of rated illuminance to

3

2

adjoining spaces;

3

2

En1~0.1 En2

3

I

3

2.5 Automatic transport facilities or conveyor belts in' or

spaces 2.6.1 Day-time operation

2

x E/

lNW,nw

Only luminaries

min 400.0~

without luminous .side panels are to be used.

2.6.2 Night-time operation

0,5 E/

lNW,nw lNW,nw

3

Only luminaries without luminous side panels are to be used.

~

, -...:l

interior. The interior area of the shed entrance is to be illuminated.

to 0,2 Ent

tEn of adjoining

tEn of the adjoining interior. The interior

area of the shed entrance is to be illuminated

l.

Table 3.5 Indoor workspaces recommended illuminance (conte'd) 1

Type or Interior and/or task 13

2

3

4

5

6

rated illuminance, Em InJ!!.

Colour appearance

Colour rendering group

Class or direct glare limitation

Remark

750

ww,nw,tw

2A

1

Leather Industry (conte'd)

13.4 Leather dyeing (mechanical) 13.5 Quality control 13.5.1 Medium standard 13.5.2 High standard 13.5.3 Very high standard 13.6 Colour matching

Fa surface inspection tasks, provide lighting with oblique incidence. Local workplace lighting recommended.

s~plementary

750 1000 1500

nw nw,tw nw,tw

1B 1B 1B

1" 1 1

100

tw,nw

1A

1

ww,nw

3

3

300 300

ww,nw ww,nw

3 2A

2 2

500 750 750 1000 1000 1500

ww,nw ww,nw ww,nw,tw ww,nw,tw ww,nw,tw nw,tw

2A 2A 2A 2A 1A 2A

1 1 1 1 1 1

Shield from light sources with a different illuminant. Local workplace lighting recommended.

14 Manufacture and processing or textiles 14.1 14.2

14.3 14.4

14.5 14.6 14.7 14.8 14.9

~

Workplaces and work zones at baths and in bate breaking areas Combing, washing, lroninq, devilling and carding work; drawing, teasing, sizing, card cutting; slubbing; jute and hemp spinning Dyeing Warping, beaming, spinning, spoiling and winding, twisting, braiding, knitting, and weaving Comb pricking; perching; sewing; block printing Millinery Trimming; burling Goods inspection; colour matching Invisible mending

200

; Local workplace lighting

I recommended. I For colour matching tasks, shield from light sources with a different iIIuminant.

Table 3.5 Indoor workspaces recommended illuminance (conte'd)

lJl

o

1

3

4

5

6

Colour appearance


Clliss of direct glare limitation

Remark

50

WVf,nw

3

3

100

.ww,nw

3

3

200

ww,nw

3

2

300 500

ww,nw ww,nw,tw

2A 2A

1 1

200

~90

ww,nw ww,nw

3 3

2 2

300

ww,nw

3

1

300

ww,nw

3

1

500 300

ww,nw ww,nw

3 3

1 1

750 200

ww,nw ww,nw

3 3

1 2

300 300 500

ww,nw ww,nw ww,nw

3 3 3

2 2 1

2 Rated

Type of Interior and/or task

illuminance, In Ix

En'

6 Smelting y(orks, Iron and steal works, roiling mills, foundrl'"!

6.1 Production plants not reqUiring manual intervention

6.2 Production plants requiring occasional manual intervention

6.3 Permanently manned workplaces in production plants

6.4 Measuring stations, control platform and observation posts

6.5 Testing and inspection areas

Where required for operational reasons, ~ may be less than 300.0!!

§. may exceed 500.0Ix

7 Metal working and flnlshl~g

7.1 Hammer-forging of small parts 7.2 Welding 7.3 Machining centres; automatic or semiautomatic machining plant

7.4 Rough and medium machining tasks, with permissible deviations greater than 0.1 mm 7.5 Precision machining tasks, with permissible deviations less than 0.1 mm 7.6 Robot-equipped workpleces 7.7 laying out and control workplaces; measuring stations

7.8 Cold roiling mills 7.9 Wire and tube drawing works; manufacture of cold rolled sectional strip

7.10 Mechl:'l and working of sheet metals re of hand tools and cutlery 7.11 Manuf

..

..... _ . _ . . . . .

_

T

•


· i

Type

or Interior and/or task

2

3

4

5

6

Rated IIlumlnance,En, In.1it

Colour appearance


Class ot direct glare limitation

Remark

ww,nw ww,nw ww,nw ww,nw

3 3 3 3

2 1 1

200 300 300 500 300

ww,nw ww,nw ww,nw ww,nw ww,nw ww,nw ww,nw ww,nw ww,nw ww,nw ww,nw ww,nw

3 3 3 3 3 3 3 3 3 3 3 3

3 3 ·3 2 2 2 2 2 2 2 1 2

300 500 750

ww,nw,tw ww,nw,tw ww,nw,tw

3 3

2A

2 1 1

1000

ww,nw,tw

3

1

7 Metal working and tlnlshlng (conte'd) 7.12 Assembly 7.12.1 low precision 7.12.2 Medium precision 7.12.3 High precision 7.13 Drop forging 7.14 Foundries c Underfloor man-sized trenches, belt 7.14.1 conveyor roads, cellars, etc. 7.14.2 Platforms 7.14.3 Sand preparation 7.14.4 Dressing room 7.14.5 Workplaces at cupola furnaces and mixers 7.14.6 Casting bays 7.14.7 Shake out bays 7.14.8 Mechanical moulding 7.14.9 Hand moulding 7.14.10 Core moulding 7.14.11 Patternmaking 7.15 Die casting works 7.16 Surface treatment 7.16.1 Electroplating 7.16.2 Priming, painting, varnishing 7.16.3 Inspection areas 7.17 Tool, gauge jig manufacture; precision mechanics; highprecision assembly

-

Vl

200 300 500

200

50 100

200 300

200 300

200

2. !

,

local workplace lighting recommended

VI

N



2

3

4

5

Colour appearance


Class of direct glare limitation

3 3 3 3 3 3 3 3

2 2

500 750

ww,nw,tw ww,nw,tw ww,nw,tw ww,nw,tw ww,nw,tw ww;nw,tw ww,nw,tw ww,nw,tw

50 100

ww,nw ww,nw

3

2 3

200 100

ww,nw ww,nw

2A

50 100 300

ww,nw ww,nw ww,nw

3

a

2A 2A

2 1

,500

ww,nw

2B

2

Rated illuminance, En' In Ix

6

I'

I

I

Remark

7 Metal working and finishing (conte'd) 7.18 Motor vehicle manufacture 7.18.1 Shell manufacture 7.18.2 Body surface treatment 7.18.3 Paint spray booth 7.18.4 Paint polishing bays 7.18.5 Retouching 7.18.6 Upholstery 7.18.7 Final vehicle assembly 7.18.8 Inspection

I. 500 500 1000 750 1000 500 .

.

1 1 2 2 1

Shielding against direct glare at asserrbly lines with local workplace fluorescent lighting may be dispensed with i '!he operational conditions so reqlire.

i·

8 Power stations 8.1 Loading plant 8.2 Iiloiler room 8.3 Pressure equalizing chamber in nuclear power stslions 8.4 Machine rooms 8.5 Ancillary rooms, e.g. pump rooms, condenser rooms 8.6 Switchboard plant 8.7 Control rooms 8.8 Maintenance work on turbine and generator

9

3

3

1 2

Where required for operational reasons, En may be less than 300.0J!. By providing supplementary lighting while work is carried out.

Electrical engineering Industry

9.1 Cable manufacture; varnishing and impregnation of coils; simple assembly tasks; winding of coils . and armatures with heavy-gauge wire

'.

300

ww,nw

3

1

TabTe3~~rindoor workspaces reeommtmded illuminance (conte'd) 1

Type of interior 81Id/or task

9

2

3

4

5

Rated illuminance, e.,. in Ix

Colour appearance



500

ww,nw,tw

3

1

6 Remark

Electrical engineering Industry (conte'd)

9.2 Assembly of telephones and small motors; winding of coils and armatures with mediumgauge wire 9.3 Assembly of precision devices; radio 81Id television sets; winding of fine wire coils; fabrication of fuses; adjustment, testing and calibration

1000

ww,nw,tw

3

1

9.4 Assembly of high-precision parts and of electronic components

1500

ww,nw,tw

2A

1

1000 1500 1500

ww,nw,tw ww,nw,tw ww,nw,tw

2A

1 1 1

100 200 300

ww,nw ww,nw ww,nw

3 3

2A

3 2 2

500

ww,nw

1A

1

500 500 750

ww,nw ww,nw nw,tw

2A 2A

Local workplace lighting recommended

10 Jewellery Industry, watch and clock making Industry 10.1 Manufacture of jewellery 10.2 Working of precious stones 10.3 Optician's and watchmaker's workshops

11

2A

Woodworking

11.1 Stearn pits 11.2 Saw mils 11.3 Bench work, gluing, assembly 11.4 Selection and inspection of veneer wood; marquetry work 11.5 Pattern making shop; polishing; varnishing 11.6 Work at woodworking machines; turning, chamfering, dressing, rebating, slotting, cutting, sawing,sinking . 11.7 Surface finishing 11.8 Checking for defects

~

1B

1A

1 1 1

Local workplace lightr,g recommended

~

.....

~

Table 3.5 Indoor workspaees recommended illuminance (conte'd) 2

3

4

Rated Illuminance, Em In Ix

Colour appearance

Colour renclerlng group

200

ww,nw

3

3

cardboard fabric8lion

300

ww,nw

3.

2

12.3 Standard bookbinding; wallpaper printing

300

ww,nw

2A

1

12.4 Trimming, gilding, embossing: work 8l printing presses

500

ww,nw

2A

1

12.5 Hand printing;paper sorting

750

ww,nw,twl<

2A

1

12.6 Retouching; lithography; hand and machine composing; make-ready

1000

ww,nw,tw

2A

1

12.7 Colour control in multi-coloured printing

1500

ww,nw,tw

1A

1

12.8 Steel and copper engraVing

2000

ww,nw,tw

2A

-1

13.1 Work 8l v8ls; tubs, pits

200

ww,nw

3

3

13.2 Scraping, splitting, smoothing, fulling of hides

300

ww,nw

2A

1

Type of Interior andlor task

6

5

!

Cia.. of direct glare limitation

Remark

12 Paper Industry, printing and allied trades 12.1 Work 8l Hollanders, edge runners, grinding mills

i

12.2 Paper-making and corrug8ling machines; Avoidance of reflected glare by selection of correct light incidence; for hand composing, obliquely from the side.

Local workplace lighting recommended.

13 Leather Industry

13.3

For tubs, due attention must be given to vertical lighting, reflections being avoided by means of suitable light incidence.

.Saddlery work; quilting; sewing polishing; sorting; pressing; cutting to size punching; shoe manufacture

!

500

ww,nw

2A

1

For dark m8lerials, increase to 1ooo.0I,!. local workplace .lighting .... lIE!Ioi ........

I

I~-...I.

...... _ ._ _ _ _ _ _ _ ..

:.-.a.

I I


2

3

4

5

6

rated illuminance, EmlnJ!

Colour appearance



Remark

13.4 Leather dyeing (mechanical)

750

ww,nw,tw

2A

1

13.5 Quality control 13.5.1 Medium standard 13.5.2 High standard 13.5.3 Very high standard

750 1000 1500

nw nw,tw nw,tw

1B 1B 1B

1" 1 1

100

tw,nw

1A

1

ww,nw

3

3

300 300

ww,nw ww,nw

3 2A

2 2

500 750 750 1000 1000 1500

ww,nw ww,nw ww,nw,tw ww,nw,tw ww,nw,tw nw,tw

2A 2A 2A 2A 1A 2A

1 1 1 1 1 1


13

Leather Industry (conte'd)

13.6 Colour matching

For surface inspection tasks, provide supplementary lighting with oblique incidence. Local workplace lighting recommended.

Shield from light sources with a different illuminarit. Local workplace lighting recommended.

14 Manufacture and processing of textiles 14.1 14.2

14.3 14.4

14.5 14.6 14.7 14.8 14.9

Workplaces and work zones at baths and in bate breaking areas Combing, washing, ir,oning, devilling and carding work; drawing, teasing, sizing, card cutting; slubbing; jute and hemp spinning Dyeing Warping, beaming, spinning, spoiling and winding, twisting, braiding, knitting, and weaving Comb pricking; perching; sewing; block printing Millinery Trimming; burling Goods inspection; colour matching Invisible mending

200

Local workplace lighting recommended. For colour matching tasks, shield from light sources with a different iIIuminant.

VI VI I

VI

0'1

Table 3.5 Indoor workspaces recommended iIIuminance(conte'd) 1

2

3

4

5

6

Em in Ix

Colour appearance

Colour rendering' group


Remark

Workplace and work zones in breweries end malthouses; washing, tiing in barrels, cleaning, sieving, peeling, cooking and boiling in canning and chocolate factories; workplaces and work zones in sugar refinwies, for drying and fermenting leaf tobaccO; fermenting cellar

200

ww,nw

2A

3

Sorting and washing of produce; grinding, mixing, packaging

300

ww,nw

2A

2

butcher's stores, dairies, mills and filter beds

300

nw

2A

2

Cutting and sorting d fruit and vegetables

300

nw

2A

1

Making of delicatessen products; kitchens; cigar and cigaJette manufacture

500

nw

2A

1

Inspection of glass jars and product control; garnishing, decorBting, and sorting

500

nw

2A

1

Colour matching; laboratories

1000

ww,nw,tw

1A

1

16.1 Sales areas

300

ww,nw

2A

1

16.2 Cash desks

500

ww,nw

2A

1

Type of interior end/or task

Rated illuminance,

15 Food and luxury food Industries 15.1

15.2

15.3

15.4

15.5

15.6

15.7

Wor~pJaces. and work zenas In abattoirs,

18 Wholesale al'ld retail trade

_ _ . _ 0_ _ _ _ _ 0. __ •

Depending on the layout of the workplace, ensure adequate vertical illuminance.

For colour matching, shield from light sources with a different illuminant. Local workplace lighting recommended.



2

3

4

5

6

Rated illuminance, Em in Ix

Colour appearance



Remark

200

ww,nw

3

2

200 300 300 500 500

ww,nw ww,nw ww,nw ww,nw ww,nw ww,nw

3 3 3 3 3 2A

2 2 2 2 1 1

17 Craft and trades (examples from different b-enches)

17.1 Removing rust and painting steel components 17.2 Subassembly of heating and ventilation system 17.3 Locksmith and plumbing work 17.4 Motor car workshop 17.5 Carpentry and joinery 17.6 Repair shops for machines and appliances 17.7 Radio and television repair workshops

1a Services enterprises

VI .--.1

18.1 Hotels and restaurants 18.1.1 Reception 18.1.2 Kitchen 18.1.3 Dining rooms 18.1.4 Conference rooms 18.1.5 Self-service restaurants 18.2 Laundries and dry cleaners 18.2.1 Washing 18.2.2 Machine ironing 18.2.3 Ironing by hand 18.2.4 Sorting 18.2.5 Stain removal inspection 18.3 Hairdressing 18.4 Beauty treatment

200 500 200 300 300

ww,nw ww,nw ww ww,nw ww,nw

2A 2A 1B 2A 1B

1 2

300 300 300 300 1000 500 750

ww,nw ww,nw ww,nw ww,nw ww,nw ww,nw,tw ww,nw,tw

2A 2A 2A 2A 2A 1A 1A

2 1 1 1 1 1 1

19 Plastics processing 19.1 Injection moulding 19.2 Blowing 19.3 Compression moulding

500 300 300

ww,nw ww,nw ww,nw

3 3 3

2 2 2

1 1

Local workplace lighting permitted

,"

.

... ",

~

..

." '!,"

• tit

00

Table 3.6 Outdoor workspaces "

1 Type of outdoor workspace circulation areas/zones and workshops

2

3

Rated illuminance, En in !!

Uniformity of illuminance, gl =

50

0.5

3

s"in

5

g2'~0.08

4

Su. £min.. and g2 related ta the centreline

£m~

g21~ 0.3

4

£min and 9:;, relate to

s.~

4 Colour rendering group

5

Remarks

1 Circulation areas on works premises, works roads 1.1 Gates 1.2 Footpaths

shall be 1.0L,minimum.

cithepath. 1.3 Cycle paths

path. 1.3.1 Works roads with loading and unloading zone or with heavy cross traffic and a speed limit of 30.0km/h or less

10

0.4

4

1.3.2 Works roads with loading and unloading zone or with heavy cross traffic and a speed limit of 50.0km/h or less

20

0.4

4

3

0.2

4

20

0.2

4

2 Parking areas 3 Harbours 3.1 Container transshipment areas 3.1.1 Open storage areas and circulation areas 1) g~=Emin/£m~

-

the centre line of the

Table 3.6 Outdoor workspaces (conte'd) 1

2

3

Rated illuminance, g", in Ix

Uniformity of illuminance, 9! =E~

3.1.2 Loading and unloading containers 3.2 Quayage 3.2.1 Quayside 3.2.2.Loading unit loads 3.2.3 Loading bulk goods (dry bulk and fluids) 3.3 Workspaces in depot areas 3.3.1 Unit loads 3.3.2 Bulk goods 3.3.3 Hazardous fluids 3.4 Wharfs for passenger traffic 3.5 Wharfs for mixed traffic 3.6 Docks 3.7 Repair facilities in harbour

100

0.2

4

S~plementary

5 20· 10

0.2 0.2 0.2

4 4 4

Dazzling of shipping to be avoided.

20 5 5 30 50 50 50

0.2 0.2 0.2 0.2 0.2 0.2 0.2

4 4 4 3 3 4 4

4 Transshipment areas, loading areas

30

0.5

4

5 Workspaces in depot areas, stacks 5.1 Piece goods 5.2 Bulk goods

30 10

0.2 0.2

4 4

Type of outdoor workspace, circulation areas/zones, and workshops

IS

4

5


Remarks

3 Harbours (conte'd)

6 Track system 6.1 Sidings, shunt yards 6.1.1 Public transport 6.1.2 Other traffic 6.2 Platforms 6.3 Rehandling yards 6.4 Level crossing

VI \0

3 5 30 20

local workplace lighting required in containers.

0\

o

Table 3.6 Outdoor workspaces (conte'd) ..

1

Types of outdoor workspace, Circulation areas/zones, and workshops

2

Rated illuminance, EN in Ix

3

Uniformity of illuminance, gl-=-Em~

4

5


Remarks

7 Building sites 7.1 7.2 7.3 7.4

Overground workings Underground workings Structural steelwork, structural metalwork Tunnelling

8 Larg.scale chemical production plant

20 20 20 30

0.2 0.2 0.2 0.2

4 4 4 4

10

0.2

4

10 20

0.2 0.2 0.5

4 4 4

3 20

0.2

4 4

5

0.2

9 Power stations 9.1

Circulation areas 9.1.1 Conventional fuel power stations 9.1.2 Nuclear power stations 9.2 Switchboard plant

20

10 Open cast mining 10.1 Directional lighting 10.2 Supplementary working zone lighting

11 Sewage treatment works 11.1 Paths and roads 11.2 Tanks and basins

12 Filing stations

.

100

-

4 4

0.5

3

Lighting only where needed

Table 3.7 1

Types of space or activity

Guideline values for educational establishment lighting 2

3

4

5

Rated Illuminance, ~ In Ix

Colour appearance

Colour rencterlng property group

Quality class of direct glare restriction

50 20

ww,nw ww,nw

3 3

.

200 200

ww,nw ww,nw

2 2

2 2

If necessary, supplementary lighting for steeks cabinets

100 100 100 200

ww,nw ww,nw ww,nw ww;nw viW,nw ww,nw

2 2 2 2 2 2

3 2 3 1 2 1

If necessary, supplementary lighting for objects eXhibited, platforms and shelves.

ww,nw ww,nw ww,nw ww,nw

2 2 2 2

1 1 1 2

6

Remarks -

1 Outside structures 1.1 Roofed recreation area 1.2 Roofed bicycle stands

-

2 Secondary rooms for special purposes 2. 1 Room for teaching aids and collections 2.2 Projection

3

Community rooms

3.1 Corridors 3.2 Staircases 3.3 Entrance halls 3.4 Canteens 3.5 exhibition rooms 3.6 Multi-purpose rooms 3.7 Auditoria, rooms for functions, if not included under 3.6 above 3.8 Libraries (books, other media) 3.9 Reading rooms 3.10 Book stack-rooms

0 f-'

roo 300 100 300 500

200

0\

tv

Table 3.7 Guideline values for educational establishment lighting (conte'd) 1

Type of space or activity

2

3

4

5

Rated illuminance, E. In..!!

Colour appearance

Colour rendering property group

Quality class of direct glare restriction

4 General.teachlng rooms 4.1 Rooms for pre-schooling purposes 4.2 Teaching rooms, if not included under 4.3 below 4.3 Teaching rooms with a day-light factor .Q (see DIN 5034 Part 1) less than 1% at the most unfavourable working position, teaching rooms used chiefly in the evening or specially for adult education 4.4 Open-plan teaching spaces - with high reflectance 3 - with medium reflectance

300 3001

ww,nw ww,nw

2 2

1t 1t

5O
ww,nw

2

1t

750 1000

ww,nw ww,nw

2 2

1 1t

500 500 500 500 500 500 700

ww,nw ww,nw ww,nw ww,nw ww,nw ww,nw ww,nw

2 2 2 1 2 2 2

2 2 1 1 1 1 1

500 750

ww,nw ww,nw

2 2

1 1

t

6

Remarks

The main chalkboard and/or demonstration desk require supplementary lighting. 1) At the working positions, a minimum of O.Ss, is required. 2) The "luminance required if the room is put to other uses can be attained by switching parts of the lighting system 3) High reflectance is deemed to be at least 0.7 for the ceiling, at least 0.5 for the walls or room dividers.

5 Teaching rooms for special purposes 5.1 5.2 5.3 5.4 5.5 5.6 5.7

Kitchens for teaching purposes Rooms for manual training Rooms for handicrafts, sewing, typewriting Drawing, painting Physics, chemistry and biology Laboratories, demonstration rooms Technical drawing 4

8 Lecture theatres 6.1 Lecture theatres with windows 6.2 Lecture theatres without windows

t The values of the Iwninance restriction curve belonging

to the next highest nominal illuminance shall be observed

4) En with respect of the drawing-board positioned as for use at 75° from the horizontal, the centre of the board being 7at a height of 1.2m

Table 3. 8 Guidance value for hospital lighting

Room type

Bedded area

Type 01 activity I type illumination

01

Rated illuminance, ~,In!!

Ughtlng colour

colour renderinggro Up1

Quality class for restriction 01 direct glare

1 1 1 1 1

1 1 1 1 1

General lighting Reading lighting Examination lighting Night watch lighting Night lighting

100 200 300

-

ww ww ww ww ww

Infants ward

General lighting Night-watch lighting

200 20

ww ww

1 1

1 1

General examination and treatment rooms

General lighting At site of examination

500 >1000

ww,nw ww,nw

1 1

1

Gyna~ology

500 50 50 50

WW,nw ww,nw ww,nw ww,nw

1 1 1 1

1 1 1 1

General lighting Refractometry Skiascopy Ophthalmoscopy Ophthalmometry Perimetry Adaptometry

500 50 50 50 50 5 5

ww,nw ww,nw ww,nw ww,nw ww,nw ww,nw ww,nw

1 1 1 1 1 1 1

1 1 1 1 1 1 1

General lighting Work at monitor

500 20

ww,nw ww,nw

1 1

1 1

'Remarks

, Reduced glare for patients Approximately 5.0~ i

General lighting at workplaces not less than 160.0Ix

-

Special examination and treatment rooms For endoscope examination

For ophthalmic examination

for radiographic examination

, 0'1 I

W

Preparation Urology Rectoscopy

If required, switchable or

controllable to give lower

illuminance values

"

If required, switchable or

controllable to give lower

illuminance values

0'1

Table 3. 8 Guidance value for hospital lighting (conte'd)

~

Room type

Ughting colour

colour rendering groupl)

Quality class for restriction of direct glare

-

nw nw nw

1 1 1

1 1 1

500

nw

500

nw

500 500 500 500 500 100

nw 1

1

nw nw ww,nw

1

1

General lighting

300

ww,nw

1

1

General room lighting General lighting in beddes areas

100

ww

1

1

500

WW

1

1

General lighting Colour check

500 1000

ww,nw

1 1

1 1

Type of activity f Type of illumination

Rated illuminance,

s... in!!

Remarks

Special examination and treatment rooms (conte,d) for dental examinations for dermatological examinations Intensive care areas Operating 1heatre suites

Ancillary rooms

Therapy rooms Medicinal baths PhysiotherapyMassage Dialysis rooms

Laboratories and dispensaries

General lighting Operating field lighting Surround lighting in operating theatre General lighting for changing rooms Wash rooms Rooms for pre-surgery preparation Rooms for post-surgery treatment Instrument stories Sterile parts stoles Sterilization stores Recovery room Recovery lighting

1000

nw nw

tw

Illuminance: from 20000 to 100000.0Ix, tooo.ou minimum; desired illuminance: 2OOO.01x

Reduce
Reduced glare for patients

Workplace lighting, if required.

Table 3. 8 Guidance value for hospital lighting (conte'd)

Room type

Corridors and stairs

Type of activity I Type of Illumination Bedded areas - day-time - at night Operating theatre suit - day-time - at night

Rated illuminance ~, in Ix

Lighting colour

Colour rendering group1

Quality class for restriction of direct glare

200 50

ww ww

2 2

1

300 100

nw nw

2 2

1 1

100

ww

1

-

200

1

Sanitary blocks connecting to bedded areas Toilets Dirty work areas

300

ww ww,nw

2

-

Duty rooms for doctorsand nursing staff

General lighting Lighting for difficult visual tasks

300 500

ww ww

1 1

1 1

Post-mortemexamination rooms

General lighting Workplace lighting

1000 >5000

nw nw

1 1

1

Toilets and dirty work areas

0\

VI

.

I

Remarks

2

-

If required, workplace lighting for filling hypodermic syringes, sorting medicines etc.

j'

ELECTICAL INSTALLATION OF BUILDINGS

SECTION

4

CONDUCTORS

4.1

SCOPE

1) This Section of the Code specifies the nominal cross-sectional areas of conductors in electric cables and cords used for lighting, appliance and power supply circuits for a nominal voltage not exceeding 1.OkV. 2) The conductors include solid and stranded copper and aluminium conductors in cables for fixed installation and flexible copper conductors. 3) The provisions of this Section do not apply to conductors for telecommunication purposes.

4.2



66

(a) BS 7671:1992

Requirements for Electrical Regulations Sixteenth Edition.

(b) BS 6360:1991

Specification for Conductors in Isolated Cables and Cords.

(c) IEC 228: 1976

Conductors of Insulated Cables.

(d) IEC 50(461): 1984

International Electrotechnical Vocabulary.

(e) IEC 364-5-523:1993

Electrical Installation of Buildings.

EBCS-1 0 1995

Installation,

lEE

Wiring

ETHIOPIAN BILDING CODE STANDARD

SECTION 4: CONDUCTORS

(f) C22.1:1990

4.3

Canadian Electrical Code, Part I, Safety Standard for Electrical Installations, Sixteenth Edition.

DEFINITIONS

(1) For the purpose of this Section of the Code, the following definitions shall apply in addition to those tenus defined in Section 1.

conductor (of a cable)

a part of a cable which has the specific function of carrying current.

plain conductor

a metal conductor in which the wire or wires are not coated with an additional metal.

metal coated conductor

a conductor in which eacn individual wire is covered with a thin layer of a different metal or metal alloy,

solid conductor

a conductor consisting of a single wire. (A Solid conductor may be circular or shaped otherwise.)

shaped conductor

a conductor the cross-section of which is other than circular.

stranded conductor

a conductor consisting of a number of individual wires, all or some of which generally have a helical fohn. (The stranded conductor may be circular or shaped otherwise.)

flexible conductor

a stranded conductor having wires of diameters small enough and so assembled that the conductor is suitable for use in a flexible cable.

concentric conductor

a conductor so constructed as to surround one or more insulated conductors.

insulation (of a cable)

. insulating materials incorporated in a cable with the specific function of withstanding voltage.

extruded insulation

insulation consisting generally of one layer of a thermoplastic or thermosetting material and applied by extrusion process.

ETHIOPJAN BUILDING CODE STANDARD

EBCS-10 1995

67

ELECTICAL INSTALLATION OF BUII.DINGS

mineral insulation

insulatron consisting of compressed mineral powder.

conductor screen

an el<;:ctricalscreen of non-metallic and/or metallic material covering ~/1e conductor.

Insulating screen; core screen

an electrical screen of non-metallic material covering the insulation.

shield (of a cable)

a surrounding earthed metallic layer to confine the electric field , within the cable and/or to protect the cable from external electrical influence. (Metallic sheaths, armours and earthed concentric conquctors may also serve as shields).

)

core (insulated conductor) an p.ssembly comprising a conductor with its own insulation (and screen if any). sheath (jacket)

a uniform and continuous circular covering of metallic or non metallic material, generally extruded.

oversheatn

a non-metallic sheath applied over a metallic covering, constituting the outer-most sheath of the cable.

armour

.a covering consisting of a metal tape(s) or wires, generally used to :' protect the cable form external mechanical effects.

slngle-cond/lctor cable; single-corecable

a cable having only one core.

multiconductor cable

a cable having more than one core.

multicore cable

a .cable having more than one core.

flat (multicore) cable

a multicore cable having cores or groups of cores arranged in parallel flat formation.

flexible cable

a cable which is required to be capable of being flexed while in service and of which the structure and materials are such as to fulfil this requirement.

68

EBCS-10 1995


SECTION 4:. CONDUCTORS

cord

a flexible cable with a limited number of conductors of small cross sectional area.

aerial (insulated) cable

an insulated cable designed to be suspended overhead and outdoors.

heating cable

a cable withorwithout a shield or a metallic sheath, intended to give off heat for heating purposes.

4.4

SIZE OF CONDUCTORS

4.4.1 Phase Conducton in a.e, Circuits and Live Conducton in de circuits .(1) The minimum nominal cross-sectional area of conductor shall be:

a) .1.Omm 2 for cables and insulated copper conductors for power and lighting circuits;

b) 1O.Omm2 for bare copper conductors for power circuits;

c) 16.0mm2 for bare aluminium conductors for power circuits; .

d) O.Smm2 for flexible cables of copper conductors for extra low voltage.

4.4.2 Neutral Conductors (1) For a polyphase circuits in which imbalance may occur in normal service, the neutral conductor shall have a cross-sectional area adequate to carry the maximum connected load between the neutral I and anyone ungrounded conductor.

(2) For a polyphase circuit in which serious imbalance is unlikely to occur in normal service, other than a discharge lighting circuit, multicore, cables incorporating a reduced neutral conductor may be used. When single-core cables are used- in such circuits, the neutral conductor shall have a cross-sectional area appropriate to the expected value of the neutral current. (3) In a discharge lighting circuit, the neutral conductors shall have a cross-sectional area not Jess than that of the phase conductor(s).


EBCS-10 1995

69

""

._._--------"."-----


4.5

AMPACITY OF WIRES, CABLES AND FLEXIBLE CORDS

4.5.1

Conductor Operating Temperature

(1) The current to be carried by any conductor for sustained periods during normal operation shall be such that conductor operating temperature given'i~'tl1e appropriate table. of current carrying capacity in Annex B ofthis Section is not exceeded,

4.5.2

Cables Connected in Parallel

(1) Except for a ring final circuit, cables connected in parallel shall be of the same construction, of cross-sectional area, length and disposition, without branch circuits and arranged SO as to carry substantially equal current.

4.5.3

Cables Connected to Bare Conductors or Busbars

(1) Where a cable is to be connected toa bare conductor busbar, its, type of insulation andior sheath shall be suitable for the maximum operating temperature ofthe bare conductor or busbar,

4.5.4

Voltage Drop

(1) The size of conductors shall be such that the voltage,drop between the supply terminal and

fixed current-using equipment shall not exceed 4% of the nominal voltage of the supply line when the conductors are carrying the full lo~d current.

4.6 FLEXIBLE CORDS (1) Flexible cords may be used for: a) electrical equipment for household or similar use having a rating of t6~OA or less at voltages not exceeding,230.0V and which is intended to be moved from place to place; b) electrical equipment for industrial use which must be capable ofbeing moved from place to place for operation; c) pendants; d) the connection of stationary equipment to facilitate its interchange; e) the connection of electrical components between which relative motion is necessary; f) the connection of appliances such as ranges and clothes dryers; g) ·supplying of current of portable lamps and other devices.or exhibition purposes; h) wiring of cranes and hoists.

70

EBCS-10 1995

ETHiOPIAN BILDING CODE STANDARD

SECT~ON 4: CONDUCTORS

(2) Flexible cord shall not be used: a) as a substitute for the fixed wiring of structures and shall not be: i)

permanently secured to any structural member; or

ii) run through holes in walls, ceilings,or floors; or

iii) run through doorways, windows, or similar openings;

b) at temperature above the temperature rating of the cord or at a temperature sufficiently low as to be liable to result in damage to the insulation or overall covering; c) for the suspension of any device weighing more than 2.3kg unless the cord and device assembly are marked as capable of supporting a weight upto II.Okg. (3) Flexible cord shall be protected by insulating bushing or in some other acceptable manner where it enters 01' passes through the enclosure wall or the partitioning of a device or enters a lampholder. (4) Where a flexible cord is used as an extension cord or to plug into an appliance or other device, no live parts shall be exposed when one end is connected to a source of supply and the other end is free. 4.7

COLOUR OF CONDUCTORS

(1) Colour identification of conductors shall be as specified in Tables 4.1 and 4.2 4.8

MAXIMUM PERMISSIDLE TEMPERATURE

(1) Any cable must be capable of withstanding.the maximum expected short-circuit current in

its circuit for the maximum expected disconnection time of its protective device without exceeding the maximum permissible temperature given in Table 4.3


EBCS-10 1995

71

- - - - _.. ~--------------------~


Table 4.1 Colour identification of cores of flexible cables and cords

Number of cores

Function of core

Colour(s) of core

1

Phase Neutral Protective

Brown Blue Green-and-yellow

2

phase Neutral

Brown Blue

3


Brown Blue Green-and-yellow

4 or 5


Brown or black Blue .Green-and-yellow

Table 4.2

Colour identification of cores of non-flexible cable and - bare conductors for fixed wiring

Function

Colour identification-

Protective (including earthing) conductor

Green and yellow

Phase of a.c. single - phase circuit

red or yellow or blue

Neutral of a.o. single or three-phase circuit Phase R of 3- phase circuit

black red

Phase Y of 3-phase a.c. circuit

yellow

Phase B of 3-phase a.c. circuit

blue

Positive of d.c. 2-wire circuit

red black

Negative of d.c. 2-wire circuit Outer (positive or negative) of d.c. 2-wire circuit derived from 3-wire system Positive of 3-wire d.c. circuit Middle wire of 3-wire d.c. circuit ~egative

72

red red black blue

of 3-wire d.c. circuit

EBCS-10 1995



Table 4.3 Maximum conductor operating temperature

Conduot or material Copper·

700C p.v.c (general purpose) 600C rubber 850C rupber 900C thermosetting Impregnated paper

Copper

Minerai • Plastic covered or exposed to touch • Bare and neither exposed to touch nor in contact with combustible materials

Alumlniu m

t

Ineulatlon materl.1

700C p.v.c (general purpose) 85°C p.v.c 60°C rubber 85°C rubber goDC thermosetting Impregnated paper

Conductor op....tlng t.mp.ratur. °C

Umltlng final temperature °C

70 60 85 90 80

160/140t 200 220 250 160

70 (sheath) 105 (sheath)

160 250

70 85 60 85 90 80

160/140t 160/140 t 200 220 250 160

above 300.0m2


EBCS·10 1995

.73

ANNEX

PREFACE TO THE TABLES IN ANNEX At ANI).' ANNEX n- FO,R CABLES AND FLEXIBbE CORDS .,:'

A.I

BASIS OF TABULATED CURRENT-CARRYING CAPACITY

The current-carrying capacity set out in Annex B takes account of lEe Publication 364-5-523(1983), so far as the later is applicable. For types of cable not treated in the mc publication (e.g. armoured cables), the current-carrying capacity of Annex B is based on data provided by ERA Technology Ltd. ttt, and the British Cable Makers' Confederation (see also ERA Report 69-30 'current Rating Standards for Distribution Cables"), The tabulated current-carrying capacity relates to continuous service and is also known as the full thermal current rating' of the cable, corresponding to the conductor operating temperature indicated in the headings to the tables concerned. It is intended to provide for a satisfactory life of conductor and insulation subject to the thermal effects of carrying current for sustained periods in normal service. A cable may be seriously damaged, leading to early failure, or its service life may be significantly reduced, if it is operated for any prolonged period at a temperature higher than the indicated value. In addition, there are other considerations affecting the choice of the cross-sectional area of a conductor, such as the requirements for protection against electric shock, protection against thermal effects, overcurrent protection (see A.5 below), voltage drop (see A.7 below) and the limiting temperatures for terminals of equipment to which the conductors are connected.

t

tt ttt 74

Annex A: Correction factors Annex B: Current-carrying capacity and voltage drop ERA Technologies Ltd, Cleave Road, Leatherhead, Surrey KT22 7SA

EBCS-10 1995



The tabulated current-carrying capacity relates to a single circuit in the installation methods shown in Annex A of Section 8, in an ambient air temperature of 30°C. The current-carrying capacity given in the tables for a.c. operation apply only to frequencies in the range 49.0 to 61.0Hz. For other conditions, appropriate correction factors are to be applied as described below. The current ratings given for. single-core armoured cable are for the condition of armour bonded at (both ends and to earth.

A.2

CORRECTION FACTORS .FOR CURRENT-CARRYING CAPACITY

The current-carrying capacity of a cable for continuousservice is affected by grouping, by ambient temperature, by partial or total enclosure in thermal insulating and for a.c., by frequency. Annex A provides relevant correction factors as in the following: "

A.2.t Grouping Tables A.I, A2 and A3 give the correction factors to be applied to the tabulated current carrying capacity where cables or c~rcuits are grouped.

A-2.2 Ambient temperature

\

Tables A4 and A.S give the correction factor to be 'applied to the tabulated current-carrying capacity depending upon the actual ambient temperature of the location in which the cable is to
,.

ETHIOPIAN BUILDING COgE STANDARD

EBCS-10 1995

75.


A.2.3 Other frequencies In extreme cases, notably for large multicore cables, the reduction in current-carrying capacity of cables carrying, for example, balanced 400.0Hz a.c, compared with the current-carrying capacity at 50.0Hz, may be as much as 50%. For small cables and flexible cords, such as may be 'used to supply individual tools, the difference in the 50.0Hz and the 400.0Hz current-carrying capacities may be negligible.

A.3

EFFECTIVE CURRENT-CARRYING CAPACITY

The current-carrying capacity of a cable corresponds to the maximum current that can be carried in specified conditions without the conductors exceeding the permissible limit of steady state temperature for the type of insulation concerned. The values of tabulated current represent the effective current carrying capacity only where no correction factor is applicable; otherwise, the current-carrying capacity corresponds to the tabulated value multiplied by the appropriate factor or factors for ambient temperature, grouping and thermal insulation, .~ applicable. Irrespective of the type of overcurrent protective device associated with the conductors concerned, the ambient temperature correction factors to be used when calculating current carrying capacity (as opposed to those used when selecting cable sizes) are those given in Table A.4.

A.4

RELATIONSIDP OF CURRENT-CARRYING CAPACITY CIRCUIT PARAMETERS

TO" OTHER

The relevant symbols used in Annex A and Annex B are as follows: I,

the current-carrying capacity of a cable for continuous service, under the particular installation conditions concerned.

II

the value of current tabulated in Annex B for the type of cable and installation method concerned, for a single circuit in an ambient temperature of 30°C.

I,

the design current of the circuit, i.e, the current intended to be carried by the circuit in normal service.

76 EBCS-10 1995

ETHIOPIAN'SUffi]'ING CODE STANDARD

~--_.

__. _ - - - - _ ._ _

.~~-----,-.--'-----

'\

SECTION 4: CONPUCTORS

""'.

'."".

':,:

\~

the nominal current or current setting of the device protecting the circuit against ',i ..

overcurrent, the operating current (i.e. the fusing current or tripping current for the conventional operating time) of the device protecting the circuit against overload.

12

Co -

A correction factor to be applied where the installation conditions differ from those for which values of current carrying capacity are tabulated in AnnexB. The various correction factors are identified as follows':

c. CL

for ambient temperature

for grouping

C1

for thermal insulation

C,

for operating temperature of conductor.

In all circumstances, Iz must be not less than lb' and I, also must be not less than Ib, Where the overcurrent device is intended to afford protection against overload, 12 must not exceed 1.451z and I, must not exceed I~ (see A.5 below). Where the overcurrent device is intended to afford short circuit protection only, I, can be greater than I, and 12 can be greater than 1,45Iz•

A.5

OVERLOAD PROTECTION

Where overload protection is required, the type of protection provided does not affect the current-carrying capacity of a cable for continuous service (lJ, but it may affect the choice of conductor size. The operating conditions of a cable are influenced not only by the limiting conductor temperature for continuous service, but also by the conductor temperature which might be attained during the conventional operating time of the overload protection device, in the event of an overload. This means that the operating current of the protective device must not exceed 1,45Iz . Where the protective device is a fuse or a miniature circuit-breaker, this requirement is satisfied by selecting a value of I, not less than In, In practice, because of the standard steps in nominal rating of fuses and circuit-breakers, it is often necessary to select a value of In exceeding lb' In that case, because it is also necessary for


EBCS-10 1995

77


I, in tum to be not less than the selected value of In' the choice of conductor cross-sectional area may be dictated by the overload conditions and the current-carrying capacity conductors will not always be fully used.

OJ

of the

The size needed for a conductor protected against overload by a semi-enclosed fuse can be .~ obtained by the use of a correction factor, 1.45/2=0.725, which results in the same degree of protection as that afforded by other overload protective devices. This factor is to be applied to the nominal rating of the fuse as a divisor, thus indicating the minimum value of It required of the conductor to be protected. In this case also, the choice of conductor size is dictated by the overload conditions and the current-carrying capacity (lJ of the conductors cannot be fully used.

A.6

DETERMINATION OF THE SIZEOF CABLE TO BE USED

Having established the design current (Tb) of the 'circuit under consideration, the appropriate procedure described in A-6.1 to A-6.4 below will enable the designer to determine the size of .the cable that will be necessary to use. As a preliminary step, it is useful to identify the length of the cable run and the permissible voltage drop for the equipment being supplied,as this may be an over-riding consideration (see A,7 below). The permissible voltage drop in mV, divided by Ib and by the length of run, will give the value of voltage drop in mv/Alm which can be tolerated. A voltage drop not exceeding that value is identified in the appropriate table and the corresponding cross-sectional area of conductor needed on this account can be read-off directly before any other calculations are made. The conductor size ne~essary from consideration of the conditions of normal load and overload is then determined, All correction factors affecting I, (that is, the factors for ambient temperature, grouping and thermal insulation) can, if desired, be applied to the values of I, as multipliers. This involves a process of trial and error until a cross-sectional area is reached which ensures that I, is not less than I, and not less than I, of any protective device that is 'intended to seiect. In any event, if a correction factor for protection by a semi-enclosed fuse is necessary, this has to be applied to ~ as a divisor. It is, therefore, more convenient to apply all the correction factors to ~ as divisors. L~'l;;d\ .

This ineth~d is used in A,6.1 through A,6.3 and'~produces .~ \falue of current and that value (or the next larger value) can readily be located in the appropriate table of current-carrying capacity and the corresponding cross-sectional area of conductor can be identified directly. It should be noted that the value of I, appearing against the chosen cross-sectional area is not Iz • It is not

78

":EBC$.. tb'··:f~~5

..,



necessary to know I, where the size of conductor is chosen by this method; but if it is desired to identify I, the value is determined by the method indicated in A3 above. However, this method cannot be used for cables installed in enclosed trenches (Installation Methods 18, 19 and 20 of Annex A, Section 8) because the correction factors given in Table A3 are related to conductor cross-sectional areas. For such cables, it is, therefore, necessary to use the process of trial and error described above, selecting on a trial basis a particular size of cable from, for instance, voltage drop considerations. A.(i.l' Overload protection afforded by a fuse or a miniature circuits breaker

(1) For single circuits -

divide nominal current of the protective device (I..) by any applicable correction factor for ambient temperature (C.) given in Table A4.

-

then further divide by any application for thermal insulation (CJ

(2) The size of cable to be used shall be such that its tabulated current-carrying capacity (L) give in Equation (A.1) below is not less than the value of nominal current of the protective device adjusted as above:

I

t, ~ .:»:

Ca~

(AI)

(Ampere)

(3) For groups -

divide the nominal current of the protective device (1..) by the correction factor for grouping (C g) given in Table~ AI, A2, or A3:

It

I

~ ~

Cg

(A2)

(Ampere)

Alternatively, it may be selected in accordance with the following formulae, provided that the circuits of the group are not liable to simultaneous overload:


EBCS-101995

79


(.'\.3)

I t > Ib

~

and

I,

~ ~I;+O.48I; (1~::]

(A.4) (Ampere)

The size of cable to be used shall be such that its tabulated single-circuit current-carrying capacity (IJ is not lessthan the value of I, calculated in accordance with Equation (A.2) above or, where Equations.(AJ) and (A.4) are used, not less thanthe larger of the resulting values of I..

two

Where correction factors C, and/or C, are applicable, they are to be applied as divisors to the value of I. determined by the above formulae. A.6.2

Protection 'devi~e a

semi-en~lo8ed

fuse

(1) For single circuits

~ divided the nominal current of the fuse Ou) by any applicable correction factor for ambient temperature (CJ given in Table A.S; • then further divide by any applicable correction factor for thermal insulation, (e l) ; ~

then further divide by 0.725.

The size of cable to be used shall be such that its tabulated current-carrying capaci1;y
It ~

In O.725C Il

80

EBCS~ 10

1995

c,

(A.s) (Ampere)



(2) For groups

- divided the nominal current of the fuse I, by 0.725 and by the applicable correction factot for grouping (C s) given in Tables A.1, A.2 ,or A.3

I> ~ t - 0.725 C

(A. 6)

(Ampere)

g

Alternatively, ,. it may be selected by the following formulae, provided that the circuits of the group are 40t liable to simultaneous overload.

I >

(A. 7)

t, Cg

t -

and

It

~

1.91;+0.481;

[1-~:]

(A. 8)

(Ampere)

"Cg

The size of cable to be used shall be such that its tabulated single-circuit current-carrying ,: capacity (It) is not less than the value of I, calculated in accordance with Equation (A.6) above or, where Equation (A. 7) and (A.8) are used, not less than the larger of the resulting two values of It1; Where correction factors C. and/or C, are applicable, they are to be applied as divisors to the va~~e of I, determined by the above Equation.

4.6.3 Overload protection not required ;Where the cable under consideration is not required to be protected against overload, the design current of the circuit (Ib) is to be divided by any applicable correction factors, and the size of the cable to be used shall be such that its tabulated current-carrying capacity (Ljgiven by


EBCS-10 1995

81

------------------~---

ELECTRICAL INSTALLATION OF BUILDINGS . ., Equation (A.9) below for the installation method concerned is not less than the value of Ib adjusted as above: (A.9)

t, It?:' CCc. a g

(Atnpere)

1

A.6.4 Variation of installation conditions along a cable route ·<1 The procedures in A.6.1 through A.6.3 above are based on the assumption that allthe conditions necessitating the use of correction factors apply to the same part of the route of the conductors of the circuit. Where various factors apply to different parts of the route, each part may be treated separately or, alternatively, only the factor or combination of factors appropriate to the most onerous conditions encountered along the route may be applied to the whole of the route. It is permissible to obtain more precise factors by calculation of the various conductor temperature rises that will occur along such a route, provided that the appropriate limiting temperature of the conductor is nowhere exceeded. I

A.7

-

TABLES OF VOLTAGE DROP

In the tables, values of voltage drop are given for a current of one ampere for a metre run, i.e,

for a distance of 1.0m along the route taken by the cables, and represent the result of the voltage drops in all the circuit conductors. The values of voltage drop assume that the conductors are at their maximum permitted normal operating temperatures. The values in the tables, for a.c.-operation, apply only to frequencies in the range 49-.0Hz to 61.0Hz; and for single-core armoured cables, the tabulated values apply where the armour is bonded to earth at both ends.. The values of voltage drop for cables operating at higher frequencies may be substantially gre~ter.· For a given run, to calculate the voltage drop (in mY) the tabulated value for the cable concerned has to be multiplied by the length of the run in metres and by the current the cable is intended to carry; namely, the design current of the circuit (lb) in amperes. For three-phase circuits, the tabulated mVI Aim values relate to the line voltage and balanced conditions have been assumed.

82

EBCS-10 1995


---'--

._---_.-~----_._._----,


_For cables having conductors of 16.0mm2 or less cross-sectional area, their inductances can be ignored and (mV/Afm)r values only are tabulated. For cables having conductors greater than 16.0mm2 cross-sectional area, the impedance values are given as (mV/Afm)z' together with the resistive component (mV/Afm)r and the reactive component (mV/Afm)x. The direct use of the tabulated (mV/Afm)r or (mV/Afm)z values, as appropriate, may lead to pessimistically high calculated values of voltage drop or, in other words, to unnecessarily low values of permitted circuit lengths. For example, where the design current of a circuit is significantly less than the effective current-carrying capacity of the cable chosen, the actual voltage drop would be less than the calculated value because the conductor temperature (and, hence, its resistance) will be less than that on which the tabulated mV/Afm had been based. As regards power factor in a.c, circuits, the use of the tabulated mV/Afm values, (tor the larger cable sizes, the tabulated (mV/Afm)z values) to calculate the voltage drop is strictly correct only when the phase angle of the cable equals that of the load: When the phase angle of the cable does not equal that of the load, the direct use of the tabulated mV/Afm or (mV/Afm)z values leads to a calculated value of voltage drop higher than the actual value. In some cases, it may be advantageous to take account of the load power factor when calculating voltage drop. Where a more accurate assessment of voltage drop is desirable the following methods may be used. (a) Correction for operating temperature shall be carried as follows: For cables having conductors of 'cross-sectional area 16.0mm 2 or less, the design value of mV/Afm is obtained by multiplying the tabulated value by a factor C, given by

230

I~

- ~)(t + tp - (C:C: ag I,2 P

~=--

30)

(A. 10)

t

230

+

'»

where tJ, is the maximum permitted normal operating temperature, °C. Equation (A. I0) applies only where the overourrent protective device is other thari a fuse and where the actual ambient temperature is equal to or greater than 30°C. /


EBCS-10 1995

83


Note:

For convenience, the aboveformula is basedon the resistancs-temperature coefficient of 0.004 per °Cat 20 °C for both copper and aluminium conductors.

For cables having conductors of cross-sectional area greater than 16.0mm:l, only the resistive . component' of the voltage drop is affected by the temperature and the factor C, is therefore applied only to th~ tabulated value of (mV/Alm1 and the design value of (mV/Nm)z is given by the vector sum of C, (mV/Alm)r and (mV/Nm'h. For very large conductor SIzeS where the resistive component of voltage drop is much less than the corresponding reactive part (i.e when x/r~3) this correction factor need not be considered. (b) Correction for load power factor, For cables having conductors of cross-sectional area of i6.0mm2 or less, the design value of mV/ Aim is obtained approximately by multiplying the tabulated value by the power factor of the load, cos tP. For cables having conductors of cross-sectional area greater than 16.0mm2 the design value of mV/Aim is given approximately by: costP [tabulated (mV/Alm)rl +sintP [(tabulated (mV/Alm)xl For single-core cables in flat formation, the tabulated values apply to outer cables and may underestimate for the voltage drop between an outer cable and the centre cable for cross sectional areas above 240.0mm 2 and power factors greater than 0.8. (c) Combined correction for both operating temperature and load power factor From (a) and (b) above, where it is considered appropriate to correct the tabulated mV/Aim values for both operating temperature and load power factor, the design values of mV/ Aim are given as follows: i) For cables having conductors of 16.0mm2 or less cross-sectional area: C, cos tP (tabulated mV/Alm) ii) For cables having conductors of cross-sectional area greater than 16.0mm2 :

Ctcos tP (tabulated mV/Alm)r) + sin tP (tabulated mV/Alm)x)'

.84

EBCS-10 1995


.

_-'=_~-O..=__.:...._".JI

ANNEX

..----

A

(NORMATIVE)

CORRECTION FACTORS Table AJ: Correction factors for groups of more than one circuit of single-core cables, or more than one multicore cable

(To be applied to the corresponding current-carrying capacity for a single circuit in Tables B.I through 8.8, B.9 through B.16, B.17 throughB.19, B.20, B.27, B.28, B.31 through B.38, B.39 through B.46 t )

Reference method of installation (see Annex a.-A of Section 6)

Correction factor (CJ Number of circuits or multicore cables 2

3

4

5

6

7

6

9

10

12

14

16

16

20

0.80

0.70

0.65

0.60

0.57

0.54

0.52

0.50

0048

0045

0043

0.41

0.39

0.38

Touching

0.85

0.79

0.75

0.73

0.72

0.72

0.71

0.70

-

-

-

Spaced tt

0.94

0.90

0.90

0.90

0.90

0.90

0.90

0.90

0.90

0.90

0.90

Touching

0.86

0.81

o.n

0.7

0.74

0.73

0.73 0.72

0.71

0.70

Spaced tt #

0.91

0.89

0.88

0.8

0.87

-

-

-

-

Horizonl81

0.90

0.85

-

-

-

-

-

-

Vertical

0.85

-

-

-

-

-

-

0.66

0.82

0.80

0.79

0.76

0.76

0.78

Enclosed (Method 3 or 4) or bunched and clipped direct lD a non- metallic surface (method 1)

-

-

-

0.90

0.90

0.90

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

o.n

-

-

-

-

-

Single layer clipped to non-metallic surface (Method 1)

i

Single layer multicore on a perforated metal cable tray, vertical or horizontal (method 11)

Single layer single core on a perforated metal cable tray, touching (Method 11)

Single layer multicore touching on ladder supports (Method 13)

t

1

-

-

-

When cables having differing conductor operating temperatures are grouped together, the current rating shall be based upon the lowest operating temperature of any cable in the group.

tt Spaced by a clearance between adjacent surfaces of at least one cable diameter (OJ where the horizontal clearances between adjacent cable exceeds 2D", no correction factor need be applied. #

00

V\

Not applicable to mineral insulated cables, see Table A.2.

.~_~~_~

~

_----'-__

~~J
(Installation Methods 18, 19 and 20 of Annex A, Section 8)t The correction factors tabulated below relate to the disposition of cable illustrated in Item No. 18 to Item No. 20 of Annex A, Section 8, and are applicable to the current carrying capacities for Reference Methods 12 or 13 of Annex A, -Seetion 8, as given in the relevant tables of this Annex.

Installation Method 18 conductor cross sectional area

2 single-core cables, or 1 three- or fourcore cable

3 single-core cables, or 2 two-core cables

4 single-core cables, or 2 three- or fourcore cables

6 single- core cables, 4 twocore cables, or 3 three- or four-core cables

1

2

3

4

5

6

7

4 6 10 16

0.93 0.92 0.91 0.91

0.90 0.89 0.88 0.87

0.87 0.85 0.84

0.82 0.81 0.80 0.78

0.86 0.86 0.85 0.83

25 35 50 70 95

0.90 0.89 0.88 0.87 0.86

0.86 0.85 0.84 0.82 0.81

0.82 0.81 0.79 0.78 0.76

0.76 0.75 0.74 0.72 0.70

120 150 185 240 300

0.85 0.84 0.83 0.82 0.81

0.80 0.78 0.77 0.76 0.74

0.75 0.74 0.73 0.71 0.69

4"00 500 630

0.80 0.78 0.77

0.73 0.72 0.71

[mm~

"

Installation Method 19

~.86

Installation Method 20

6 single- core' 12 single-core cables, 4 two 8 single-core cables, 8 twocore cables, cables, or 4 core cables, Of-3 three- or three- or four- or 6 three- or four- core core cables four-core cables cables

12 single core cables, 8 two-core cables, or 6 three- or four core cables

18 single-core cables, 12 two-cere cables, or 9 three- or four core cables

24 singlecore cables, 16 two-core cables, or 12 three- or fourcore cables

8

9

10

11

0.83 0.82 0.80 0.78

0.76 0.75 0.74 0.71

0.81 0.80 0.78 0.76

0.74 0.73 0.72 0.70

0.69 0.68 0.66 0.64

0.81 0.80 0.78 0.77 0.75

0.76 0.74 0.73 0.72 0.70

0.69 0.68 0.66 0.64 0.63

0.74 0.72 0.71 0.70 0.68

0.67 0.66 0.64 0.62 0.60

0.62 0.60 0.59 0.57 0.55

0.69 0.67 0.65 0.63 0.62

0.73 0.72 0.70 0.69 0.68

0.68 0.67 0.65 0.63 0.62

0.61 0.59 0.58 0.56 0.54

0.66 0.64 0.63 0.61 0.59

0.58 0.57 0.55 0.53 0.52

0.53 0.51 0.49 0.48 0.46

0.59 0.58 0.56

0.66 0.64 0.63

0.60 0.58 0.57

0.52 0.51 Q.49

0.57 0.56 0.54

0.50 0.48 0.47

0.44 0.43 0.41

-.....

0.67 0.66 "0.65

,

t

~

when cables having different conductor operating temperatures are grouped together, the current rating shall be based on the lowest operating temperature of any cable in the group:

oe oe

Table A.4 Correction factors for ambient temperature where protection is against short-circuit 'Note

This table applies where the associated overcurrent protective device is intended to provide short-circuit protection only. Except where the device is a semi-enclosed fuse, the table also applies where the device is intended to provide overload protection. '

Type of insulation

Operating temperature

Ambient temperature °c 25

30

35

40

45

50

55

60

65

70

75

80

85

90

95

Rubber (flexible cables only)

60°C

1.04

1.0

0.91

0.82

' 0.71

0.58

0.41

-

-

-

-

-

-

-

-

General purpose p.v.c.

70°C

1.03

1.0

0.94

0.87

0.79

0.71

0.61

0.50

0.35

-

-

-

-

-

-

Paper

80°C

1.02

1.0

0.95

0.89

0.84

0.77

0.71

0.63

0.55

0.45

0.32

-

-

-

-

Rubber

8SoC

1.02

1.0

0.95

0.90

0.85

0.80

0.74

0.87

0.60

0.52

0.43

0.30

-

-

-

Heat resisting p.v.c.t

8SoC

1.03

1.0

0.97

0.94

0.91

0.87 .

0.84

0.79

0.71

0.61

"0.50

0.35

-

-

-

90°C

1.02

1.0

0.96

0.91

0.87

0.82

0.76

·0.71

0.65

0.58

0.50

0.41

0.29

-

1.03 1.02

1.0 1.0

0.93 0.96

0.85 0.92

0.77 0.88

0.67 0.84

0.57 0.80

0.45 0.75

0.31 0.70

-

-

-

-

-

-

0.65

0.60

0.54

0.47

0.40

0.3

Thermosetting Mineral'

70°C sheath 10SoC

NOTE: (i) Correction factors for flexible cords and for 85°C or 150°C rubber insulated flexible cables are give in the relevant table of current-carrying capacity.

(ii) This table also applies when determining the current-canying capacity of a cable. (t) These factors are applicableonly to rating in Columns 2 through 5 of Tables B.l and B.2. I

..

.

Table A.5 Correction factors for ambient temperature where the overload protective device is a semi-enclosed fuse Ambient temperature

FCJ

Operating Type of insulation

temperature

25

30

35

40

45

50

55

1.0

0.96

0.91

0.87

0.79

0.56

FCJ Rubber (flexible cables only)

60

1.04

General purpose p.v.c.

70

1.03

1.0

0.97

0.94

0.91

0.87

0.84

Paper

80

1.02

1.0

0.97

0.95

0.92

0.90

0.87

60

I

65

85

90

95

-

-

-

-

70

75

80

-

-

,

-

0.69

0.48

-

-

-

-

-

-

0.84

0.76

0.62

0.43

-

-

-

-

-

-

-

i

Rubber

85

1.02

1.0

0.97

0.95

0.93

0.91

0.88

0.86

0.83

0.71

0.58

0.41

Heat resisting p.v.c. *

85

1.03

1.0

0.97

0.94

0.91

0.87

0.84

0.80

0.76

0.72

0.68

0.49

0.90

1.02

1.0

0.98

0.95

0.93

0.91

0.89

0.87

0.85

0.79

0.69

0.56

0.39

-

-

70, sheath

1.03

1.0

0.96

0.93

0.89

0.86

0.79

0.62

0.42

-

-

-

-

-

-

I 0.98

0.96

0.93

-0.91

0.89

0.86

0.84

0.82

0.79

0.77

0.64

0.55

0.43

\

Thermosetting Mineral: Bare and exposed to touch p.v.c. covered

Bare and not exposed to touch

I

105, sheath

1.02

1.0

1

•

These factors are applicable only to ratings in columns 2 to 5 of Tables B.I and B.2.

Correction factors for flexible cords and for 85°C or 150°C rubber-insulated flexible cables are given in the relevant table of current-carrying capacity.

Note:

~

~

ANNEX

B (NORMATIVE)·

TYPE OF CABLE AND AMPACITY Table B.I Single-core P.V.C. insulated cables, non-armoured, with or without sheath (copper conductor) Current-carrying capacity (Amperes)

Ambient temper-ature : 30°C Conductor operating temperature: 70° C f

Conductor crosssectional area

!

Reference Method 3 (enclosed in conduit on a wall or in trunking etc.)

2 cables, single-phase ac. or d.c.

2 cables, single-phase ac. or d.c.

3 or 4 cables three-phase ac.

3 or 4 cables three-phase ac.

Reference Method 1 (clipped direct)

2 cables, single-phase ac, or d.c. flat and touching

Reference Method 11 (on a perforaled cable tray horizontal or

vertical)

3 or 4 cables !lYee- phase ac. flat and touching or trefoil

2 cables, single-phase a.c, or d.c. flat and touching

3 or 4 cables three phase ac. flat and touching or trefoil

Reference Mehod 12 (free air) Horizontal flat

Vertical flat

spaced

spaced

2 cables single-phase ac. ad.c. a 3 :abies three-phase

2 callies, single-phase ac. or d.c. cr :3 cables tlYee-phase

ac,

ac.

Trefoil

3 cables trefoil !lYee phase . ac.

1

2

3

4

5

e

7

II

9

10

11

12

mm2

mV

mV

mV

mV

mV

mV

mV

mV

mV

mV

mV

1 1.5

11 14.5

10.5 13.5

13.5 17.5

12 15.5

15.5 20

14 18

-

-

-

2.5 4 6 10 16

19.5 26 34 46 61

18 24 31 42 56

24 32 41 57 76

21 28 36 50 68

27 37 47

25 33

-

-

-

25

80 99 119 151 182

73 89 108 136 164

101 125 151 192 232

112 141 172 223 273

146 181 219 281 341

',30 162 197

110 137 167 216 264

210 240 273 320 367

188 216 245 286 328

269

. 396 456

:!62 0419 0480

35 50 70 95

120 150 185 240

300 400 500 630 800 1000

Note:

Reference Method 4 (enclosed in conduit in thermally insulating wall etc.)

.

-

.

43 59

87

79

89. 110 134 171 207

114 141 182 234 284

104 129 167 214 261

330 381

303 349

436

400

404 463

515 594

472

456

239 262 296 346 394

549

545

635

318 369 424 504 584

-

546

467

694

626 720

533

634 723

-

-

792 904 1030 1154

732 835 953 1086 1216

679 778 892 1020 1149

65

300 341

400

-

611

-

826 943 1058

i) Where the conductoris to be protected by a semi-enclosed fuse, see A.6.2 of the preflll:C to this Annex.

ii) The current-carrying capacitiesin columns 2 to S are also applicable to flexible cables where the cables are used in fixed inslll11ations.

126 156 191 246

300

349

521 515

-

:<:54 :!11

569

109

659

852 982 ' 138 "265 "420

920 1070 1188 1'337

795

308

356 409 485 561 656 749 855 971 1079

Table B.2 Voltage drop (per ampere per meter) Conductor operating temperature : 70°C 2 cables- single-phase Conduct or crosssectional area

~

t

2 cables d.c,

3 or 4 cables - three-phase

B.C.

Reference Methods 3 and 4 (Enclosed in conduit etc. in or on a wall)

Reference Methods 1 and 11 (clipped or direct on trays, touching)

Reference Method 12 (spaced t )

Reference Methods 3 and 4 (Enclosed in conduit etc. in or on a wall

B.C.

Reference Methods 1, 11 and 12 (in trefoiQ

Reference Methods 1 and 11 (Flat and touching)

Reference Method 12 (flat spaced t)

'\

1

2

3

4

5

8

7

8

9

mrTf

mV

mV

mV

mV

mV

mV

mV

mV

1 1.5

44 29

44 29

44 29

44 29

38 25

38 25

38 25

38 25

2.5 4 6 10 16

18 11 7.3 4.4 2.8

18 11 7.3 4.4 2.8

18 11 7.3 4.4 2.8

18 11 7.3 4.4 2.8

15 9.5 6.4 3.8 2.4

15 9.5 6.4 3.8 2.4

15 9.5 6.4 3.8 2.4

15 9;5 6.4 3.8 2.4

r

x

z

r

x

z

r

x

z

r

x·

z

25 35 50 70 95

1.75 1.25 0.93 0.63 0.46

1.80 1.30 0.95 0.65 0.49

0.33 0.31 0.30 0.29 0.28

1.80 1.30 1.00 0.72 0.56

1.75 1.25 0.93 0.63 0.47

0.20 0.195 0.190 0.185 0.180

1.75 1.25 0.95 0.66 0.50

1.75 0.29 1.80 1.25 0.28 1.30 0.93 0.28 0.97 0.63 0.27 0.69 0.47 0.27 0.54

1.50 1.10 0.81 0.56 0.42

0.29 0.27 0.26 0.25 0.24

1.55 1.10 0.85 0.61 0.48

120 150 185 240 300

0.36 0.29 0.23 0.180 0.145

0.39 0.27 0.31 0.27 0.25 0.27 0.1950.26 0.160 0.26

0.47 0.41 0.37 0.33 0.31

0.37 0.30 0.24 0.185 0.150

0.175 0.175 0.170 0.165 0.165

0.41 0.34 0.29 0.25 0.22

0.37 0.29 0.24 0.185 0.150

0.26 0.26 0.26 0.25 0.25

0.45 0.39 0.35 0.31 0.29

0.33 0.27 0.22 0.17 0.14

0.23 0.23 0.23 0.23 0.23

0.41 0.36 0.32 0.29 0.27

400 500 630 800 1000

0.105 0.086 0.068 0.053 0.042

0.1300.26 0.29 0.110 0.26 O.~ 0.094 0.25 0.27

0.120 0.098 0.081 0.068 0.059

0.160 0.155 0.155 0.150 0.150

0.20 0.185 0.175 0.165 0.160

0.115 0.093 0.076 0.061 0.050

0.25 0.24 0.24 0.24 0.24

0.27 0.26 0.25 0.25 0.24

0.12 0.220.25 0.10 -0.22 0.25 0.08 0.22 0.24

-

I

r

x

z

1.50 1.10 0.80 0.55 0.41

0.175 0.170 0.165 0.160 0.155

1.50 1.10 0.82 0.57 0.43

1.50 1.10 0.80 0.55 0.41

0.25 0.24 0.24 0.24 0.23

1.55 1.10 0.84 0.60 0.47

0.32 0.150 0.26 0.150 0.21 0.145 0.160 0.145 0.130 0.140

0.36 0.30 0.26 0.22 0.190

0.32 0.23 0.26 0.23 0.21 0.22 0.160 0.22 0.130 0.22

0.105 0.'140 0.086 0.135 0.0720.135 0.060 0.130 0.0520.130

0.175 0.160 0.150 0.145 0.140

0.105 0.21 0.086 0.21 0.072 0.21 0.060 0.21 0.052 0.20

r

x

z

r

x

z

1.50 1.10 0.80 0.55 0.40

0.32 0.32 0.32 0.31 0.31

1.55 1.15 0.86 0.63

0.40 0.34 0.31 0.27 0.25

0.32 0.30 0.26 0.30 0.21 0.30 0.160 0.20 0.130 0.29

0.44 0.40 0;36 0.34 0.32

0.24 0.23 0.22 0.22 0.21

0.100 0.29 0.081 0.29 o.oes 0.28 0.053 0.28 0.044 0.28

0.31 0.30 0.29 0.29 0.28

0.~1

i

-

-

Spacing larger than those specified in Method 12(see Annex A, section 8) will result in larger voltage drop.

Table B.3 Multicore P.V.C. insulated cables, non-armoured .(copper conductors)

tS

Ambient temperature: 30°C Conductor operating temperature: 7(y>c

Current-carrying capacity (Amperes): I

Conductor . cross se tional c area

I Reference Method 4 (enclosed in an insulated wall, etc.)

Reference Method 3 (enclosed in conduit on a wall or ceiling, or in trunking)

Reference Method 11 (on a perforated cable tray) or Reference Method 13 (free air) I

. t 1 two-core cable . I h sing e-p ase a.c. d or .c,

1 three core t cable or 1 four bi thre core ca e, e h p ase a.c..

1 two-core cablet, single-phase a.c. ord.c.

1 three-core cable t or 1 fourcore cable, threephase a.c.

1

2

3

4

5

IS

mm2

A

A

A

A

A

1 two-core cablet, single-phase a.c. or d.c.

1 three-core cal?let or 1 fourcore cable, threephase a.c,

7

8

9

A

A

A

13.5 17.5

17 22

14.5 16.5

1 three-core 1 two-core cablet . cable t or 1 foursingle-phase a.c. core cable, threeord.c. phase a.c.

i

1 1.5

11 14

10 13

13 16.5

11.5 15

15 19.5

2.5 4 6 10 16

18.5 25 32 43 57

17.5 23 29 39 52

23 30 38 52 69

20 27 34 46 62

27 36 46 63 65

24 32 41 57 76

30 40 51 70 94

25 34 43 60 60

25 35 50 70 95

75 92 110 139 167

66 83 99 125 150

90

80

111 133 166 201

99 116 149 179

112 136 168 213 256

96 119 144 184 223

119 146 160 232 262

101 12.6 153 196 236

120 150 185 240 300

192 219 248 291 334

172 196 223 261 298

206 225 255 297 339

299 344 392 461 530

259 299 341 403 464

328 379 434 514 593

276 319 364 430 497

402

634

557

715

597

232 258

I,

294 844

1 I

394

I 400

t


-

-

4-~O

.

I

-.

With or Without protective conductor. 2

Circular conductors are assumed for sizes up to and including 16.0mm • Values for larger sizes relate to shaped conductors and may safely be applied to circular conductors. Note: Where the conductor is to be protected bya semi-enclosed fuse, see A.6.2 of the Preface to this Annex.

,I .J

I 1


'Table B.4 Voltage drop (per ampere per meter)

Conductor operating temperature : 70°C

Conductor Cross-sectional area

Two-core cable d.c ..

mm 2

mV

Two-core cable singlephase a.c.

Three-or four-core cable three-phase a.c,

mV

mV

,.,

. . .n

••• · · ....

1 1.5

44 29

44 29

38 25

2.5 4 6 10 16

18 11 7.3 4.4 2.8

18 11 7.3 4.4 2.8

15 9.5 6.4 S.8 2.4

r '

x

25 35 50 70 95

1.75 1.25 0.93 0.63 0.46

1.75 1.25 0.93 0.63 0.47

0.170 . 0.165 0.165 0.160 0.155

120 150 185 240 300

0.36 0.29 0.23 0.180 0.145

0.38 0.30 0.25 0.190 0.155

0.155 0.155 0.150 0.150 . 0.145 \

400

'0.105

0.115

0.145


z

x

r

z

1.75 1.25 0.94 0.65 0.50

1.50 1.10 0.80 0.55 0.41

0.145 0.145 0.140 .0.140 Q.135

1.50 1.10 0.81 0.57 0.43

0.41 0.34 0.29 0.24 0.21

0.33 0.26 0.21, 0.165 0.135

0.135 0.130 0.130 0.130 0.130

0.35 0.29 0.25 0.21 0.185

0.185

0.100

0.125

0.160

EBCS-10 1995

93

\0 ~

Table D.S Single-core armoured P.V.C. insulated cables, non-magnetic armour

j

(copper conductors)

Current-Carrying Catpacity (Amperes): Conductor operating temperature: 70°c Reference Method 1 (clipped direct) Conductor crosssectional area

Note:

Reference Method 11 on a perforated cable tray

2 cables,

Reference Method 12 (free air)

2 cables single-phase a.c.

2 cables d.c.

2 cables, single-phase a.c. or d.c. flat and touching

3 or 4 cables, three-phase a.c. flat and touching

shinglephase a.c. flat and touching

3 or 4 cables three-phase a.c. and touching

Horizontal flat spaced

Vertical flat spaced

Horizontal spaced

1

2

3

4

5

6

7

8

mm2

A

A

A

A

A

A

50 70 95

193 245 296

179 225 269

205 259 313

169 238 285

229 287 349

120

342

309

360

327

401

3 or 4 cables, three-phase a.c.

Vertical, spaced



3 cables trefoil

9-

10

11

12

A

A

A

A

A

217 272 332

229 294 357

216 279

230 286 338

212 ,263 313

161 231 280

383

415

396

385

35'7

324

340

i

185 240 300

447 525 594

399 465 515

469 550 624

422 492 547

511 593 668

489 568 640

548 648 748

525 622 719

490 566 616

456 528 578

425 501 567

400 500 630 800 1000

687 763 643 919 975

575 622 669 710 737

723 805 891 976 1041

618 673 728 777 808

737 8fO 893 943 1008

707 777 856 905 967

885 1035 1218 1441 1685

851 997 1174 1390 1627

674 721 771 824 872

632 676 723 7720 816

657 731 809 886 945

Where the conductor is to be protected by a semi-enclosed fuse, see A.6.2 of the Preface to this Annex.

Table 8.6 Voltage drop (per ampere per metre) Conductor operating temperature: 70De 3 or 4 cables - three-phase a.c.

2 cables - single-phase a.c. Conductor crosssectional area

2 cables d.c.

Reference Methods 1 and 11 (Touching)

Reference Method 12 (spacedl)

Reference Methods 1, 11 and 12 (in trefoil touching)

Reference Methods 1 and 11 (Flat and touching)

Reference Method 12 (Flat spaced')

1

2

3

4

5

6

7

mrn"

mV

mV

mV

mV

mV

mV

"

r

t

\0 Vi

x

z

r

z

x

r

z

x

r

x

z

r

x

z

50 70 95

0.93 0.63 0.46

0.93 0.64 0.48

0.22 0.21 0.20

0.95 0.68 0.52

0.92 0.66 0.51

0.30 0.29 0.28

0.97 0.72 0.58

0.80 0.56 0.42

0.190 0.180 0.175

0.82 0.58 0.45

0.79 0.57 0.44

0.26 0.25 0.25

064 062 050

0.79 0.59 0.47

0.34 0.32 0.31

0.86 0.68 0.57

120 150 185 240 300

0.36 0.29 0.23 0.180 0.145

0.39 0.31 0.26 0.20 0.160

0.195 0.190 0.190 0.180 0.180

0.43 0.37 0.32 0.27 0.24

0.42 0.34 0.29 0.23 0.190

0,.28 0.27 0.27 0.26 0.26

0.50 0.44 0.39 0.35 0.32

0.33 0.27 0.22 0.175 0.140

0.170 0.165 0.160 0.160 0.155

0.37 0.32 0.27 0.23 0.21

0.36 0.30 0.25 0.20 0.165

0.24 0.24 0.23 0.23 0.22

0.43 0.38 034 0.30 0.28

0.40 0.34 0.29 0.24 0.20

0.30 0.30 0.29 0.28 0.28

0.50 0.45 0.41 0.37 0.34

400 500 630 1300 1000

0.105 0.066 0.068 0.053 0.042

0.140· 0.120 0.105 0.095 0.091

0.175 0.22 0.170 0.21 0.165 0.195 0.160 0.185 0.155 0.180

0.180 0.165 0.150 0.145 0.140

0.24 0.23 0.22 0.21 0.190

0.30 0 .29 0.27 0.25 0.24

0.120 0.105 0.091 0.082 0.079

0.130 0.145 0.145 0.140 0.135

0.195 0.180 0.170 0.160 0.155

0.160 0.145 0.135 0.125 0.125

0.21 0.026 0.20 025 0.195 0.23 0.180 0.22 0.165 0.21

0.21 0.190 0.175 0.170 0.165

0.25 0.24 0.22 0.195 0.170

0.32 0.30 0.28 0.26 0.24

1

Spacings larger than those specified in Method 12 (see Annex A, Section 8) will result in larger voltage drop.


Table B.7 Multicore armoured P.V.C. insulated cables· (copper conductor) Current-carrying capacity (Amperes): Ambient temperature: 30°C Conductor operating temperature: 70°C Reference Method 1 (Clipped direct)

Conductor cross-sectional area

1 two-core cable, Single-phase a.c. or d.c.

I

1

- -.2

rnrn" 1.5 2.5

I

-.-----~----

I

1 three or four core cable, three-phase a.c.

I

I

4

5

A

A

A

A

16 25

22 31

33

41

42 56 77

53

10 16

21 26 36 49 67 69

19 26 35 45 62 ·63

25 35 50 70 95

116 145 175 222 269

102 125 151 192 231

126 157 190 241 291

120 150 165 240 300

310 356

267 306

336 366

400

4

96

1 two-core cable, single-phase a.c. or d.c.

1 three or four core cable, three-phase a.c. 3

6

Note:

Reference Method 11 (on a perforated horizontal or vertical cable tray), or Reference Method· 13 (free air)

72 97

110 135 163

207 251

547

346 409 469

592

290 332 376 445 510

621

540

663

590

405

476

439 516

Where the conductor is to be protected by a semi-enclosed fuse, see A. 6.2 of the Preface to this Annex.

EBCS-10 1995



Table B.8 Voltage drop (per ampere per metre)

Conductor operating temperature: 70·C


Two-core cable d.c.

1

2

Two-core cable singlephase a.c,

three or four-core cable, three-phase a.c.

3

4

I

rnrn"

mV

mY

mV

1.5

29

29

25

2.5 4

6

10

16

18

11

7.3 4.4 2.8

18

11

7.8 4.4

15

9.5 6.4 3.8

2.6

2.4

r

x

z

x

r

25

35

50

70

95

1.75 1.25 0.93 0.63 0.46

1.75 1.25 0.93 0.63 0.47

0.170 0.165 0.165 0.160 0.155

1.75 1.25 0.94 0.65 0.50

0.41~

0.145 0.145 0.140 0.140 0.135

120

150

185

240

300

0.36 0.29 0.23 0.180 0.145

·0.38 0.30 0.25 0.190 0.155

0.155 0.41 0.155 0.34 0.150 0.29 0.150 0.24 0.145 0.21

0.33 0.26 0.21 0.165 0.135

0.135 0.130 0.130 0.130 0.130

0.35 0.29 0.25 0.21 0.185

400

0.105

0.115

0.145 0.185

0.100

0.125

0.160


1.50 1.10 0.80 0.55

z

EBCS-10 1995

1.50 1.10 0.81 0.57 0.43

97

. ,~•..s

\0

Table B.9 Single-core cables having thermosetting insulation, non-armoured, with or without sheath

00

(copper conductors) Current carrying capacity (Amperes):

Conduct or cross sectlona : I area

Reference Method 4 (enclosed in conduit in thermally Insulating wall etc.)

Ambient temperature: 30°C Conductor operating temperature: 90°C Reference Method 3 (enclosed in conduit on a wall or in . . . Reference Method 1 (clipped direct) trunking etc.)

Reference Method 11 (on a perforated cable tray horizontal or vertical

Reference Method 12 (fee air) Horizontal flat spaced,


Trefoil

a,c.

2 cables single phase ac. or d.c,

3 or 4 cables three- phase ac.

2 cables single-phase ac. or d.c. flat and touching

3 or 4 cables three-phase ac. flat and trunking or trefoil

2 cables single-phase ac. or d.c. flat and touching

3 or 4 . cables threephase ac. flat and touching or trefoil

2 cables, single phase acor d.c. or 3 cables three-phase

2 cables, single-phase ac. or d.c. or 3 cables three-phase

3 cables, trefoil threephase a.c,

2

3

4

5

8

7

8

9

10

11

12

1 1.5

14 18

13 17

17 22

15 19

19 25

17.5 23

-

-

-

-

2.5 4 6 10 16

24 33 43 58 76

23 30 39 53 70

30 40 51 71 95

26 35 45 63 85

34 46 59 81 109

31 41 54 74 99

-

-

-

-

-

-

25 35 50 70 95

100 124 149 189 228

91 111 135 170 205

126 156 189 240 290

111 138 168 214 259

143 176 228 293 355

130 161

158 195 293 308 375

140 176 215 279 341

183 226 274 351 426

163 203 246 318 389

138 171 209 270 330

120 150 185 240 300

263

235 270 306 358 410

336 375 426 500 573

299

300 341 400

328 370 433 .\ 493

413 476 545

379 436 500 590 681

436 505 579

495 570 651

686 794

398 461 530 630 730

-

683 783 900

793 904 1033 1179 1323

915 1044 1191 1358 1520

849 973 1115 1275 1436

1065

2 cables single phase a,c. or d.c.

3 or 4 cables three- phase

1

400 500 630 800· 1000

459

-

-

-

-

644 743

584

868

666

990 1130 1288 1443

764

-

209 268 326

"

769 886

1228 1423 1581 1n5

-

-

453

385

524 600 711 824

511 606 701

994 1150 1338 1485 1671

820 936 1069 1214 1349

445

Note: Where the conductor is to "be protected by a semi-enclosed fuse, see A.6.2 of the Preface to this Annex. The current-carrying capacity in Columns 2 to 5 are also applicable to flexible cables where the cables are used in fixed installations. For cable in rigid p.v.c. conduit. the values stated in Tables B.1 and B.2 are applicable. Where a conductor operates at a temperature exceeding 7rfC, it shall be ascertained that the equipment connected to the conductor is suitable for the conductor operating temperature. .

Table B.10 Voltage drop (per ampere per meter) Conductor operating temperature: 90°C 2 cables, single-phase a.c. Reference Methods 3 and 4(Enclosed in conduit etc. in or on a wall)

3 or 4 cables- three-phase .a.c, Reference Methods 3 and 4 (Enclosed in conduit etc. in or on a wall)

Reference Method 1 and 11 (Clipped direct or on trays, touching)

Reference Method 12 (Spaced t )

3

4

5

6

7

8

9

mV

mV

mV

mV

mV

mV

mV

mV

1 1.5

46 31

46 31

46 31

46 31

40 27

40 27

40 27

40 27

2.5 4 6 10 16

19 12 7.9 4.7 2.9

19 12 7.9 4.7 2.9

19 12 7.9 4.7 2.9

19 12 7.9 4.7 2.9

16 10 6.8 4.0 2.5

16 10 6.8 4.0 2.5

16 10 6.8 4.0 2.5

16 10 6.8 4.0 2.5

Conducto r cross sectional area

2 Cable s d.c.

1

2

rnrn"

r 25 35 . 50 70 95

x

z

r

x

z

r

" X

0.28 0.27· 0.27 0.26 0.26

1.85 1.35 0.99 0.68 0.49

1.85 1.35 1.00 0.70 0.51

0.31 0.29 0.29 0.28 0.27

1.90 1.35 1.05 0.75 0.58

1.85 1.35 0.99 0.68 0.49

0.190 0.180 0.180 0.175 0.170

1.85 1.35 1.00 0.71 0.52

1.85 1.35 0.99 0.68 0.49

120 150 185 240 300

0.39 0.32 0.25 0.190 0.155

0.41 0.33 0.27 0.21 0.175

0.26 0.26 0.26 0.26 0;25

0.48 0.43 0.37 0.33 0.31

0.39 0.32 0.26 0.20 0.10

0.165 0.165 0.165 0.160 0.160

0.43 0.36 0.30 0.25 0.22

0.39 0.25 0.32 0.25 0.25 0.25 0.195 0.25 0.155 0.25

400 500 630 800 1000

0.120 0.093 0.072 0.056 0.045

0.140 0.25 0.120 0.25 0.100 0.25

0.29 0.28 0.27

0.1300.155 0.1050.155 0.086 0,155 0.072 0.150 0.063 0.150

0.20 0.185 0,175 0.170 0,165

-

0.1~5 0.098 0.078 0.064 0,054

0.24 0.24 0.24 0.24 0.24

z 1.85 1.35 1.00 0.73 0.56·

r 1.60 1.15 .0.87 0.60 0.44

Reference Methods 1, 11, and 12 (In trefoil)

z

x

r

0{2.7 0.25 0.25 0.24 0.23

1.65 1.15 0.90 0.65 0.50

1.60 1.15 0.86 0.59 0.43

0.165 0.155 0.155 0.150 0.145

0.23 0.23 0.23 0.22 0.22

t

z 1.60 1.15 0.87 0.61 0.45

r

x

z

Reference Methods 12 (Flat

spacedl)

r

x

z

1.60 1.15 0.86 0.59 0.43

0.190 0.180 0.180 0.175 0.170

1.6ci 1.15 0.87 0.62 0.46

1.60 1.15 0.86 0.59 0.43

0.27 0.26 0.26 0.25 0.25

1.65 1.20 0.89 0.65 0.49

0.47 0.41 0.36 0.31 0.29

0.35 0.29 0.23 0.185 0.150

0.42 0.37 0.32 0.29 0.27

0.34 0.28 0.22 0.170 0.140

0.140 0.37 0.140 0.31 0.140 0.26 0.140 0.22 0.1400.195

0.34 0.28 0.22 0.170 0.135

0.165 0.165 0.165 0.165 0.160

0.38 0.32 0.28 0.24 0.21

0.34 0.28 0.22 0.170 0.135

0.24 0.24 0.24 0.24 0.24

0.42 0.37 0,33 0.29 0.27

0.27 0.26 0.25 0.25 0.24

0.125 0.22 0.25 0.100 0.22 0.24 0.088 0.21 0.23

0.110 0.090 0,074 0.062 0.p55

0.1350.175 0.1350.160 0.1350.150 0.1300.145 0.1300.140

0.110 0.088 0.071 0.059 0.050

0.160 0.195 0.1600.180 0.160 0.170 0.155 0.165 0.155 0.165

0.110 0.085 0,068 0.055 0.047

0.24 0.24 0.23 0.23 0.23

0.26 0.25 0.24 0.24 0.24

-

\0 \0

x

Reference Methods 1 and 11 (Flat touching)

Spacing larger than those specified in Method 12 (see Annex A, Section B) will result in larger voltage drop'

~

8 I'·

Table B.ll . Multicore, non..a rmoured cable having thermosetting insulation (copper conductors) Ambient temperature: 30"C· Conductor operating temperature: 90"C

. Current-carrying capacity (Amperes):

Reference Method 4 (enclosed in an insulated wall, etc.) Conductor CrossSectional area


Reference Method 11 (on a perforated cable tray) or Reference Method 13 (free air)

1 two-core cable single-phase a.c. or d.c.

1 three- or four-core cable three-phase a.c.

1 two-core cable singlephase a.c. or d.c.

1 three- or fourcore cable threephase a.c.

1 two-core cable singlephase a.c. or d.c.

1 three- or fourcore cable threephase a.c.

1 two-core cable singlephase a.c. 0" d.c,

1 three-or fourcore cable threephase a.c.

1

2

3

4

5

6

7

8

9

rnrn"

A

A

A

A

A

A

A

A

107

96

115

100

105 128 154 194 233

138 171 209 269 328

119 147 179 229 278

149 185 225 289 352

127 158 192 246 298

305 334 384 459 532

268 300 340 398 455

382 441 506 599 693

322 371 . 424 500 576

410 473 542 641 741

346 399 456 538 621

625

536

803

667

865

16

76-

68

91

80

25 35 50 70 95

99 121 145 183 220

89 109 130 164 197

119 146 175 221 265

120 150 185 240 300

.253 290 329 386 442

227 259 295 346 396

-

-

400

Note:

Reference Method 3 (enclosed in conduit on a wall or ceiling , or in trunking)

I

:~

I

I

741

(i) Where the conductor is to be protected by a semi-enclosed fuse, see A.6.2 of the Preface to the Annex. (ii) Where a conductor operates at a temperature exceeding 70°C, it shall be ascertained that theequipment connected to the conductor is suitable for the conductor

operating temperature.

I

!.

,.

I


Table B.12 Voltage Drop(per ampere per metre)

Conductor operating temperature : 90°C

Conductor cross- sectional area

Two-core cable d.c.


1

2

3

rnm"

mV

16

2.9

Three-or four-core cable three-phase a.c. 4 ,

mV 2.9

x

r

mV 2.5

z

r

x

z

1.85 1.35 0.99 0.67 0.50

0.160 0.155 0.155 0.150 0.150

1.90 1.35 1.00 0.69 0.52

1.60 1.15 0.86 0.59 0.43

0.'140 0.135 0.135 0.130 0.130

1.65 1.15 0.87 0.60 0.45

0.39 0.31 0.25 0.195 0.155

0.40 0.32 0.26 0.200 0.160

0.145 0.145 0.145 0.140 0.140

0.42 0.35 0.29 0.24 0.21

0.34 0.28 0.22 0.175 0.140

0.130 0.125 0.125 0.125 0.120

0.37· 0.30 0.26 0.21 0.185

0.120

0.130

0.145

0.195

0.115

0.125

0.170

25 35 50 70 95

1..85 1.35 0.98 0.67 0.49

120 150 185 240 300 400


EBCS-10 1995

101

'~ """ Table B.13 Single-core cables having thermosetting insulation, non-magnetic armour (copper conductors) Ambient temperature: 30"c Conductor operating temperature: 9O"C

Current-carrying capacity (Amperes): Reference Method 1 (clipped djrect) Conductor crosssectional area

I


~cables,

singlephase a.c. or d.c. flat and touching

3 or 4 cables, threephase a.c. flat & touching

1

2

3

mm2

A

50 70 95

237 303

Note:

Reference Method 11 (on a perforated cable tray)

2 cables single-phase

3 or 4 cables threephase a.c. flat & touching



Horizontal spaced

Vertical spaced


4

5

6

7

8

9

10

11

12

A

A

A

A

A

A

A

A

A

A

253 322 389

232 293 352

282 357 436

266 3$1 412

284 356 446

270 349 426

288 358 425

266

~67

220 277 333

331 393

222 285 346

120 150 185 240 300

425 488 557 656 755

383 437 496 579 662

449 516 587 689 792

405 462 524 612 700

504 566 643 749 842

477

519

539 614 714 805

600

497 575

688 815 943

782

485 549 618 715 810

449 510 574 666 755

402 463 529 625 720

400 500 630 800 1000

853 962 1082 1170 1261

717 791 861 904 961

899 1016 1146 1246 1345

767 851 935 987 1055

929 1032 1139 1204 1289

889 989 1092 1155 1238

1137 1314 1528 1809 2100

1094 1266 1474 1744 2026

848 923

797 8r 940 978 1041

815 918 1027 1119 1214

2 cables, singlephase a.c. or d.c. flat & touching

2 cables d.c.

a.c.

3 or 4 cables. three-phase a.c.

660

906

99~r

1042 1110

Ve~ical

flat spaced

i

i

!

3 cables trefoil

(i) Where the conductor is to be protected by a semi-enclosed fuse. see A.6.2 of the Preface to this Annex. (ii) Where a conductor operates at a temperature exceeding 7C1'C. it shall be ascertained that the equipment connected to the conductor is suitable for the conductor operating temperature.

Table B.14 Voltage drop (per ampere per metre) COnductor operating temperature: 90"C -

2 cables - single-phase a.c. Conductor cross sectional area

2 cables d.c.

1

rnrn"



Reference Methods 1, 11 and 12 (in trefoil .touching)


Reference Method 12( Flat spaced')

2

3

4

5

6

7

mV

mV

mV

mV

mV

mV

r

t

...... o

IoN

3 or 4 cables - three-phase a.c.

x

z

r

x

z

r

x

z

r

x

z

r

x

z

0.64 0.62 0.49

0.33 0.32 0.31

0.90 0.70 0.56

.0.21 0.200 0.195

1.00 0.71 0.55

0.96 0.69 0.53

0.29 0.29 0.26

1.00 0.75 0.60

0.66 0.59 0.44

0.160 0.170 0.170

0.67 0.62 0.47

0.64 0.60 0.46

0.25 0·.25 0.24

0.66 0.65 0.52

0.41 0.33 0.27 0.21 0.170

0.190 0.165 0.165 0.160 0.175

·0.45 0.36 0.33 0.26 0.25

0.43 0.36 0.30 0.24 0.195

0.27 0.27 0.26 0.26 0.25

0.51 0.45 0.40 0.35 0.32

0.35 0.29 0.23 0.160 0·145

0.165 0.160 0.160 0.155 0.150

0.39 0.33 0.26 0.24 0.21

0.36 0.31 0.26 0.21 0.170

0.24 0.23 0.23 0.22 0.22

0.44 . 0.41 0.39 0.34 0.34 0.29 0.30 0.24 0.26 0.20

0.145 0.125 0.105 0.090 0.092

0.170 0.170 0.165 0.160 0.155

0.22 0.21 0.195 0.190 0.160

0.160 0.165 0.150 0.145 0.140

0.24 0.24 0.23 0.23 0.21

0.30 0.29 0.27 0.27 0.25

0.125 0.105 0.092 0.066 0.060

0.150 0.145 0.145 0.140 0.135

0.195 0.160 0.170 0.165 0.155

0.160 0.145 0.135 0.130 0.125

0.21 0.20 0.195 0.160 0.170

50 70 95

0.96 0.67 0.49

0.99 0.66 0.51

120 150 165 240 300

0.39 0.31 0.25 0.195 0.155

400 500 630 600 1000

0.115 0.093 0.073 0.056 0.045

Spacings larger than those specified in Method 12 (see Annex A, Section 8) will result in larger voltage drop .

0.27 0.25 0.24 0.23 .0.21

0.20 0.190 0.175 0.175 0.165

0.30 0.29 0.29 0.26 0.27

0.51 0.45 0.41 0.37 0.34

0.27 0.24 0.23 0.195 0.160

0.33 0.31 0.29 0.26 0.24

------'-

---------~------


Table B.15 Multicore armoured cables having thermosetting insulation (copper conductors)

Ambient temperature : 30°C Conductor operating temperature: 90°C

Current-Carrying Capacity (Amperes):

Reference Method 11 (on perforated horizontal or vertical cable tray) or Reference Method 13 (free air)

Reference Method 1 (clipped direct) Conductor cross sectional area

1 two-core cable, single phase a.c. or d.c.

1 three-or four core cable, three-phase a.c.

1 two-core cable, single phase a.c. or d.c.

1 three-or fourcore cable, three-phase a.c.

1

2

3

4

5

rnrn"

A

A

A

A

1.5

27

23

29

2.5 4 6 10 16

36 49 62 85 110

31 42 53 73 94

39 52 66 90 115

33 44 56 78 99

25 35 50 70 95

146 180 219 279 338

124 154 187 238 289

152 188 228 291 354

131 162 197 251 304

120 150 185 240 300

392 451 515 607 698

335 386 441 520 599

410 472 539 636 732

353 406 463 546 628

400

787

673

847

728

t!'

,

I

I

25

Note:

(i) Where the conductor is to be protected by a semi-enclosed fuse, see A.6.2 of the Preface to this Annex. (ii) Where a conductor operates at a temperature exceeding 7(J'C, it shall be ascertained that the equipment connected to the conductor is suitable for the conductor operating temperature.

104

EBCS-10 1995


------"----

-._._._--_.-.-._-~-


Table B.16 Voltage drop (per ampere per meter) :"J.

Conductor operating temperature: 90°C Conductor crosssectional area

Two-core Cable d.c.


1

2

3

mm 2

mV ,"

Three-or four-core cable three-phase a.c.

4

mV

mV

-

1.5

31

31

27

2.5 4 6 10 16

19 12 7.9 4.7 2.9

19 12 7.9 ,.. 4.7 2.9

16 10 6.8 4.0 2.5

r

x

z

r

z

x

25/ 35 50 70 95

1.85 1.35 0.98 0.67 0.49

1.85 1.35 0.99 0.67 0.50

0.160 0.155 0.155 0.150 0.150

1.35 1.00 0.69 0.52

1.60 1.15 0.86 0.59 0.43

0.140 1.135 0.135 0.130 0.130

1.65 1.15 0.87 0.60 0.45

120 150 185 240 300

0.39 0.31 0.25 0.195 0.155

0.40 0.32 0.26 0.20 0.16'

0.145 0.145 0.145 0.140 0.140

0.42 0.35 0.29 0.24 0.21

0.34 0.28 0.22 0.175 0.140

0.130 0.125 0.125 0.125 0.120

0.37 0.30 0.26 0.21 0.185

400

0.120

0.13

0.145

0.195

0.115

0.125

0.170


1.90

EBCS-10 1995

105

"""" ~

Table B.17 Ssingle-core non-armoured cables having 8SoC rubber insulation (copper conductors) Ambient temperature: 30"C Conductor operating temperature: 85"C

Current-carrying capacity (Amperes): Reference Method 3 (enclosed in conduit, etc. in or on a wall) Conductor Cross sectional area

1 mm

2

.

Reference Method 1(clipped direct)

2 cables, singlephase a,c. or d.e, flat and touching

3 or 4 cables

Reference Method 11(on a perforated cable tray)Horizontai or Vertical

3 or 4 cables, three-

5

6

7

a

9

A

A

A

A

A

A

-

-

. -

-

154 192 235 3:J3 370

134 167 204 262 320

451 499 573 079

373 432 495 587 680

3 or 4 cables

phase a,c, or d.c.

three- phase a,c.

2

3

4

A

A

17

three-phase a,c. flat and touching or trefoil .

phase e,c. flat and touching or trefoil

1 1.5

15 19.5

19 25

17.5

22

2.5 4 6 10 16

30 40 52 72 96

27 36 46 63 85

34 45

59 81 108

31 42 54 75 100

. -

25 35 50 70 95

127 157 190 242 293

112 138 167 213 258

143 177 215 274 332

133 164 199

'153 189 229

140 174 211

254

308

293 356

327

120 150 185 240 300

339

298

372 428 510 593

334

384 442 519 607 695

357 411 469 553 636

412 475 542 639 735

379 437 499 589 679

827 946 1088

755

860 989 1143

798 ,918 1062

400 500 630

443

506

719

602

835

689

975

791

single-phase a,c, or d.c. or 3 or L cables 'three phase ac. flat spaced horizontal or vertical

2 cables, single phase a.c. or d.c. flat and touching

2 cable single

379


23

865

996

269

786 929

1061 1263

3 cables trefoil three-phase a.c,

-

,

799 919 1060

Note:(i) Where the conductor is to be protected by a semi-enclosed fuse, see A.6.2 oft the Preface to Annex. . (ii) Where a conductor operates at a temperature exceeding 70·C ,it shall be ascertained that the equipment connected to the conductor is suitable for the conductor operating temperature.

Table B.18 Voltage drop (per ampere per metre) Conductor operating temperature: 85°C 3 or 4 cables - three-phase a.c,

2 cables - single-phase ac.: Conductor crosssectional

2 cables d.c.

1

Reference Method 3(Enclosed in conduit etc. in or on a wall

Reference Methods 1 and 11 (clipped director on trays, touching)

Reference M~hod 12 Spaced )

Reference Method 3(Enclosed in conduit . etc. in or on a wall)

Reference Methods 1. 11, and 12 (in trefoil touching)

2

3

4

5

6

7

8

9

mm2

mV

mV

mV

mV

mV

mV

mV

mV

1 1.5

46 31

46 31

46 31

-

40 26

40 26

40 26

-

2.5 4 6 10 16

18 12 7.7 4.6 2.9

18 12 7.7 4.6 2.9

18 12 7.7 4.6 2.9

·

16 10 6.7 4.0 2.5

16 10 6.7 4.0 2.5

16 10 6.7 4.0 2.5

-

r

t I-"

s

x

z

r

x

-

· · · z

r

'x

z

r

x

z

r

x

z

. Reference Methods 1 . Reference Meth~ 12 and 11 (Flat (Flat spaced ) touching)

.

z

r

x

z

1.60 0.25

1.60

1.60

0.32

1.65

r

x

25

1.80

1:85 0.32 1.90

1.85 0.20

1.85

1.85

0.29

1.85

1.60

0.28

1.65

1.60 0.175

35 50 70 95

1.30 0.95 0.65 0.48

1.35 1.00 0.68 0.51

0.31 0.30 0.29 0.28

1.40 1.05 0.74 0.58

1.30 0.97 0.66 0.49

0.195 0.190 0.185 0;180

1.35 0.99 0.69 0.52

1.30 0.97 0.66 0.49

0.28 0.28 0.27 0.27

1.35 1.00 0.72 0.56

1.15 0.87 0.60 0.44

0.27 0.26 0.25 0.25

1.20 0.91 0.65 0.51

1.15 0.84 0.57 0.43

0.170 1.15 0.165 0.86 0.160 0.60 0.155 0.45

1.15 0.84 0.57 0.43

0.24 0.24 0.24 0.23

1.15 0.88 0.62 0.48

1.15 0.84 0.57 0.42

0.32 0.32 0.31 0.31

1.20 0.90 0.65 0.52

120 150 185 240

0.38 0.30 0.25 0.190

0.40 0.33 0.27 0.21

0.27 0.27 0.27 0.26

0.49 0.42 0.38 0.33

0.39 0.31 0.25 0.195

0.175 0.43 0.175 0.36 0.170 0.30 0.165 0.26

0.39 0.31 0.25 0.195

0.26 0.26 0.26 0.25

0.47 0.40 0.36 0.32

0.35 0.29 0.23 0.180

0.24 0.24 0.23 .0.23

0.43 0.37 0.33 0.29

0.34 0.27 0.22 0.170

0.155 0.150 0.150 0.145

0.37 0.31 0.26 0.22

0.34 0.27 0.22 0.170

0.23 0.23 0.22 0.22

0.41 0.35 0.31 0.28

0.34 0.27 0.22 0.170

0.30 0.30 0.30 0.30

0.45 0.40 0.37 0.34

300 400 500 630

0.150 0.115 0.091 0.072

0.170 0.140 0.115 0.100

0.26 0.26 0.26 0.25

0.31 0.30 0.28 0.27

0.155 0.125 0.100 0.082

0.165 0.160 0.155 0.155

0.155 0.120 0.097 0.077

0.25 0.25 0.24 0.24

0.29 0.28 0.26 0.25

0.150 0.130 0.105 0.085

0.23 0.22 0.22 0.22

0.27 0.26 0.24 0.24

0.135 0.110 0.089 0.073

0.140 0.140 0.135 0.135

0.195 0.175 0.165 0.155

0.135 0.110 0.089 0.073

0.22 0.21 0.21 0.21'

0.26 . 0.24 0.23 0.22

0.135 0.105 0.085 0.067

0.29 0.29 0.29 0.28

0.32 0.31 0.30 0.29

0.23 0.20 0.185 0.175

Spacings larger than those specified in Method 12 (see Annex A of Section 8) will result in larger voltage drop.

1.60

t-'

o00 Table B.19 Multicore, sheathed and non-armoured cables having 85°C rubber insulation (copper conductors) Ambient temperature: 30"C Conductor operating temperature: 85°C

Current-carrying capacity (Amperes): Reference Method

3 (enclosed)

Reference Method

1 (clipped direct)

sectional area

I

11 (on a perforated cable tray). or

1 two-core cable single

1 three- or four-core

1 two-core cable, single

1 three- or four-core

1 two-core cable single

1 three- or four-core cable, three-

phase a.c. or d.c.

cable, phase a.c.

phase a.c. or d.c,

cable, three-phase a.c.

phase a,c, or d.c,

phase a.c.

1

2

3

4

5

e

"7

mm2

A

A

A

A

A

A

1 1.5

6.5 21

14.5 18.5

18 23

16 20

19.5

17.5

25

22

25 33

32

34

43

55 76 103

28 37 48 66

30 40 52 71

2.5 4 6 10 16

I I

i

29 38 48 66

87 114 139 167 211

I

58 77 100 122 147

43

50 70 95

254

! ss Z"!2

136 168 201 256 310

120 150 185 240 300

292 320 368 439 509

256 287 326 381 436

359 413 470 553 636

25 35

Note: (i) (ii)

Reference Method

Refrence Metthod 13 (free air)

Conductor cross-

88

46 59 81 109

117 144 174 222 269

144 177 213 272 329

123 151 186 237 287

312

381 438 499 587 675

333 383 437 515 593

~59

409 482 555

Where the conductor is to be protected by a semi-enclosed fuse, see A.6.2 of the Preface to this Annex. Where a conductor operates at a temperature exceeding 70°C, it shall be ascertained that the equipment connected to the conductor is suitable for the conductor operating temperature.

94

I

----------'------------------'------~~---~-~~~--~~-----'----~-'---'--~-

J

I

I I


Table B.20 Voltage drop (per ampere per meter) Conductor operating temperatures: 85uC Conductor cross- sectional area

Two-core cable d.c.

Two-core cable single-phase a.c.

Three- or four-core, cable threephase a.c.

1

2

3

4

rnrn"

mV

mV

mV

1

1.5

46

31

46

31

40

26

2.5

4

6

10

16

19

12

7,7

4.6

2.9

19

12

7.7 4.6 2.9

16

10

6.7 4.0 2.5

r

x

z

x

r

25

35

50

70

95

1.80 1.30 0.95 0.65 0.48

1.85 1.30 0.97 0.66 0.49

0.175 0,170 0.170 0,165 0.160

1,85 1.35 0.99 0.68 0.52

1.60 1,15 0.84 0.58 0.43

120

150

185

240

300

0.38 0.30 0.25 0.190 0.150

0.39 0.31 0.25 0.195 0.155

0.160 0.155 0,155 0.150 0.150

0.42 0.35 0.30 0.25 0,22

0.34 0,27 0.22 0,170 0.135

z

0.150 0.150 0.145 0.140 0.140

1.60 1.15 0.86 0,59 0.45

0.135 0.135 0.130 0.130 0.130

0,36 0.30 0.26 0.22 0.185

;


EBCS-10 1995 - 109


Table B.21 60°C rubber-insulated flexible cables, other than flexible cords Current-carrying capacity: Ambient temperature: 30°C (Amperes): Conductor operating temperature: 60"C Single-phue a,c, or d.c ..

Three-phase a,c.

Single phase a.c. or d.c,

1 two-core cable with or without protective conductor

1 three-core, four-core or fivecore cable

2 single core cables

1

2

3

4

mm2

A

A

A

.-


.

--_ ....

.... _.. _--

4 6 10 16

30 39 51

26 34 47

73

63

25 35 50 70 95

97

83 102 124 158 192

.

120 150 185 240 300

222 255 291

.

400 500 630 Notes:

~

',~"

-

140 175 216 258

394

302 347 394 471 541

-

644 738 861

343

(i) The tabulated current ratings are for cables in free air, but may also be used for cables resting on a surface. If the cable is to wound on a drum on load, the ratings should be reduced in accordance with (iii) below and, for cables which may be covered, (iv) below. (ii) Where the conductor is to be protected by a semi-enclosed fuse, see A.6.2 of the preface to this Annex. (iii) The current ratings of cables used on reeling drums are to be reduced by the following factors: a) Radial type drum

i) ii)

ventilated: 85%

unventilated: 75%

b) Ventilated cylindrical type drum

i) 1 layer cable: 85%

ii) 2 layers of cable: 65 %

iii} 3 layers of cable: 45%

iv) 9 layers of cable: 35%

A radial-type drum is one where spiral layers of cable are accommodated between closely spaced flanges; if fitted with solid flanges, the ratings given above should be reduced and the drum is described as non-ventilated, and if the flanges have suitable apertures as ventilated. A ventilated cylindricalcable drum is one where layers of cable are accommodated between widely spaced flanges and the drum and end flanges have suitable ventilating apertures. (iv) Where cable may be covered over or coiled up whilst on load, or the air movement over the cable restricted, the current rating should be reduced. It is not possible to specify the amount of reduction; but the table of rating factors for reeling drums can be used

as a guide.

110

EBCS-10 1995


Table B.22 Voltage drop (per ampere per metre) Conductor operating temperature: 60"C

........ ....

t


Two-core cable d.c.


1 three-core, four-core or five-core cable three-phase a.e,

mrn"

mV

mV

4, 6 10 16

12 7.8 4.6 2.9

12 7.8 4.6 2.9 r

-x

1.80

0.175

25 35 50 70 95

1.80

120 150 185 240 300

-

-

400 500 630

-

-

-

-

-

Larger voltage drop will result if the cables are spaced .

z 1.85

r

d.c.

Single-phase a.c. t

mV

mV

mV

10 6.7 4.0 2.5

-

-

-

-

x

z

1.55 1.10 0.83 0.57 0.42

0.150 0.150 0.145 0.140 0.135

0.8~

0.33 0.27 0.22 0.170 0.135

0.135 0.130 0.130 0.130 0.125

-

-

2 single-core cables touching

-

1.55' 1.15

r

x

z

-

-

-

-

0.58 0.44

1.31 0.91 0.64 0.49

1.31 0.91 0.64 0.49

0.21 0.21 0.20 0.195

1.32 0.93 0.61 0.53

0.36 0.30 0.26 0.21 0.185

0.38 0.31 0.25 0.190 0.150

0.38 0.31 0.25 0.195 0.155

0.190 0.190 0.190 0.185 0.180

0.43 0.36 0.32 0.27 0.24

0.115 0.090 0.068

0.120 0.099 0.079

0.175 0.170 0.170

0.21 0.20 0.185

-


Table B.23 85°C or 150°C robber-insulated flexible cables Current-carrying capacity (Amperes):

Conductor cross sectionalaf8a

d.c. or singlll-phase a.c. (1 two·core cable, with or without protectIve conductor)

I

Ambient temperature: 30°C Conductor operating temperature: 85°C

Thf8e-phase a.c. (1 three cors, four-core or fivlI corB cablB)

Single phase a.c. ~r d.c. 2 singlll-corll cabllis touching

2

3

4

mnl

A

A

A

4 6

41 53 73 99

36 47 64 86

--

10

16 25 35

131

50 70

95 120 150

114

240 300

192

140 170

240

216 262

297 354

303

414 476

348 397 467 537

185

-

540

645 741 885

400 500 630

1017 1190

CORRECTION FACTOR FOR AMBIENT TEMPERATURE 85 DC rubber-insulated cables: Ambient Temperature (DC): 35 40 45 50 55 60 65 70 75 80 0.95 0.90 0.85 0.80 0.74 0.67 0.60 0.52 0.43 0.30 Correction factor: 150°C rubber-insulated cables: 35 to 85 90 95 100 105 110 115 t 120t 125 t 130135 t Ambient Temperature (0C) 1.00 0.96 0.92 0.88 0.83 0.78 0.73 0.68 0.62 0.55 0.48 Correction factor:

Ambient Temperature (0C): Correction factor: t

140t 145 0.39 0.28

Refer to notes for Table B.2l.

112

EBCS-10 1995


Table B.24 Voltage drop (per ampere per meter) Conductor operating temperature: 85"C


1 two-core or single-core cables d.c.

1

2

2 single-core cables touching


1 three-core, four-core or fivecore cable three-phase a.c.

3

4

5

Single-phase a,e, t

"'

mm"

mV

mV

mV

mV

4 6 10 16

13 8.4 5.0 3.1

13 8.4 5.0 3.1

11 7.3 4.3 2.7

-

r

"""" VJ """"

t

x

25 35 50 70 95

2.0 1.42 0.99 0.70 0.53

120 150 185 240 300

0.41 0.33 0.27 0.21 0.165

-

400 500 630

0.125 0.098 0.073

-

2.00

0.175

-

-

-

z 2.00

r

x

z

1.70 1.20 0.90 0.61 0.46

0.150 0.150 0.145 0.140 0.135

1.70 1.20 0.91 0.63 0.48

0.36 0.29 0.24 0.185 0.145

0.135 0.130 0.130 0.130 0.125

0.39 0.32 0.27 0.22 0.195

-

-

r

x

-

-

z

-

1.42 0.99 0.70 0.53

0.21 0.21 " 0.20 0.195

1.43 1.01 0.72 0.56

0.41 0.33 0.27 0.21 0.170

0.190 0.190 0.190 0.185 0.180

0.46 0.38 0.33 0.28 0.25

- 0.130 - 0.105 - 0.084

0.175 0.170 0.170

0.22 0.20 0.190

Note:(i) The voltage drop figures given above are based on a conductor operating temperature of 8SoC and are, therefore, not accurate when the operating temperature is in excess of 8S°C. In the case of the lSO"C cables with a conductor temperature of lSO"C, the above resistive values should be increased by a factor of 1.2 (This factor is only applicable to the range of lS00C rubber-insulated cables up to 16mm2 nominal cross-sectional area). (ii) larger voltage drop will result if the cables are spaced.

--------------~

---~~


Table B.25 Current-carrying capacity [Amperes] (flexible cords)

Single-phase a.c.

Three-phase a.e,

Maximum mass supportable by twin flexible cord

1

2

3

4

mm"

A

A

kg

0.5 0.75 1 1.25 1.5 2.5 4

3 6 10 13 16 25 32

3 6 10

3.


Current-carrying capacity

~-~

-

16 20 25

2 5 5 5 5 5

Where cable is on a reel, see notes to Table B.2l.

CORRECTION FACTOR FOR AMBIENT TEMPERATURE 60°C rubber and p.v.c. cords: Ambient Temperature (0C): Correction factor:

35 40 ~ 45 50 55 0.91 0.82 0.71 0.58 0.41

85°C rubber cords having a h.o.f.r. sheath or a heat-resisting p.v.c, sheath and for 85°Cheat-resisting p.v.c. cords: 55 60 65 70 Ambient Temperature (Oe): 35 to 50 Correction factor: 1.00 0.96 0.83 0.67 0.47 1500C rubber cords: Ambient Temperature (°C):35 to 120 125 130 135 140 145 Correction factor: 1.00 0.96 0.85 0.74 0.60 0.42 Glass'fiber cords: Ambient Temperature (°C):35 to 150 155 160 165 170 175 Correction factor: 1.00 0.92 0.82 0.71 0.57 0.40

\ \

114

EBCS-10 1995




Conductor operating temperature: 60 0Ct

t


d.c. or single-phase a.c.

Three-phase a.c.

1

2

3

mm"

mV

mV

0.50 0.75 1.00 1.25 1.50 2.50 4.00

93 62' 46 37 32 19 12

80 54 40

2:7 10 . 16

The tabulated values are for 60"C rubber-insulated and p.v.c-insulated flexible cords. For other types of flexible cords, they are to be multiplied by the following factors: . For 85°C rubber or p.v.c-insulated: 150"C rubber-insulated: 185°C glass fibre:

1.09

1.31

1.43


EBCS-10 1995

115

1--1 1--1

I.

Table B.27 Mineral insulated cables bare and exposed to touch (see Note ii below) or having overall covering of P.V.C.

0\

I

I

(copper conductors and sheath) Current-carrying capacity (Amperes): Reference Method 1 (Clipped Direct)

Ambient temperature: 30°C Sheath operating temperature: 70C

!

2 single core cables or 1 Conductor two-core cross-sectional . cable, singlearea . phase a.c. or d.c. I

3 single-core cables In trefolle or 1 three-core cable, threephase a.c.

3 single-core cables in flat formation, three- phase a.c. ~

1

1 four-core cable 3 cores loaded threephase a.c.

1 four-core cable all cores loaded

1 seven-core cable all cores loaded

1 twelve-core cable all cores loaded

1 nineteencore cable all cores loaded

,

2

3

4

5

6

7

8

9

rnrn"

A

A

A

A

A

A

A

A

Light duty, 500V 1 1.5 2.5 4

18.5 23 31 40

15 19 26 35

17 21 29 38

15 19.5 26

13 16.5 22

10 13 17.5

-

-

-

-

-

-

-

Heavy duty, 750V

1 1.5

19.5 25

16 21

18 23

16.5 21

14.5 18

11.5 14.5

9.5 12.0

8.5 10.0

2.5 4 6 10 16

34 45 57 77 102

28 37 48 65 86

31 41 52 70 92

28 37 47 64 85

25 32 41 55 72

19.5 26

16.0

-

25 35 50 70 95

133 163 202 247 296

112 137 169 207 249

120 147 181 221 264

110

94

-

120 150 185 240

340 388 440 514

286 327 371 434

303 346 392 457

-

-

-

-

-

-

-

-

-

-

-

i) For single-core cables, the sheaths of the circuit are assumed to be connected together at both ends. For bare cables exposed to touch, t~e tabulated values should be multiplied by O~9. ~~ _______ 0__

. -lD

I

,I, I'

1

Note:

I

-

-

-

-

_

"..

-

-

-

i

~

sheath)~(:;;~t;'d)"J

..........--------------(~-----

Jl.

(copper conductors and

u ........

qi;overall covering ofP.V.C.

.

Current-carrying capacity (Amperes): Reference Method 11 (On a perforated cable tray, horizontal or vertical)


2 singlecore cables touching

1 twocore cables

Single phase a.c. or d.c.

,

Ambient temperature; 30"C' Sheath operating temperature: 70C

1 threecore cable, threephase a.c.

1 four-core cable 3 loaded three-phase a.c.

1 fourcore cable all cores loaded

1 sevencore cable all cores loaded

1 twelvecore cable all cores loaded

1 nineteen-

3 single - core cables three-phase a.c,

core cable all cores loaded

Vertical space

Horizoota Flat I spaced touching

Trefoil

10

11

12

13

14

15

16

17

18

19

20

21

A

A

A

A

A

A

A

A

A

A

A

A

18.5 24 31 42

19.5 25 33 44

16.5 21 28 37

16 21 28

14 18 24

11 14 19

-

-

-

-

19 25 32 43

22 28 37 48

17 22

-

-

1 1.5

20 25

21 26

17.5 22

18 23

16 20

12 15.5

10 13

2.5 4 6 10 16

34 45 57 78 104

36 47 60 82 109

30 40 51 69 92

30 40 51 68 89

27 35 44 59 78

21 28

17

25 35 50 70 95

135 165 204 251 301

142 174 215 264 317

120 147 182 223 267

116

101

120 150 185 240

346 395 448 524

364 416 472 552

308 352 399 466

mm

2

Ught duty, 500V

1.0 1.5 2.5 4.0 .-

-

i

-

29'

39

I

16.5 21 28 37 I,

Heavy duty, 750V

......

...... -l

-

-

-

-

-

. .

-

-

-

-

-

-

-

-

-

-

,

,

9 11

21 27

-

35 47 59 80 105

-

-

.

-

-

-

-

-

24 30 41

i

19 25

17.5 22

67 90 119

32 43 54 ,,73 97

30 40 51 69 92

135 164 202 246 294

154 187 230 279 333

125 153 188 229 275

120 147 182 223 267

I'

335 380 424 472

382 431 482 537

314 358 405 471

308 352 399 466

I

53

Note: i) For single-core cables, the sheaths of the circuit are assumed to be connected together at both ends . ii) For bare cable exposed to touch, the tabulated values should be multiplied by 0.9.

I

I·,

.......

Table B.27 Mineral insulated cables bare and exposed to touch (see note 2) or having overall- covering of P.V.C•

......

00

(copper conductors and sheath) (conte'd) Current-carrying capacity (Amperes): Reference Methods 12 and 13 (Free air)


rnrn" ~

Light duty 500V 1 1.5 2.5 4

I

Ambient temperature: 3O"C Sheath operating temperature: 70C

3 single-core 2 single- core cables in trefoil or cables or 1 two1 three core core cable, single cable, threephase a.c. or d.c. phase a.c.

1 four-core cable 3 cores loaded threephase a.c.

1 four-core cable all cores loaded

1 sevencore cable all cores loaded

1 twelvecore cable all cores loaded

1 nineteencore cable all cores load

25

26

27

22

23

24

A

A

A

A

A

A

3 single-core cables threephase a.c.

I Touchin

Vertical spaced

Horizont al spaced

28

29

30

31

A

A

A

A

I

g

. 19.5 25 33 44

I

I

16.5 21 28 37

16 21 28

24

-

16 20

-

-

-

-

20 26 34 45

23 29 39 51

18 23 31 41

12 15.5

10 13

9 11

22 32

25 32

20 26

17

-

37 49

43

62 84 110

71 95 125

34 45 57 102

142 173 213 259 309

162 197 242 294 351

132 161 198 241 289

353 400 446 497

402 45,4' 507 565

11 14 19

14 18

-

Heavy duty, 750V

Note:

..

1.0 1.5

21 26

17.5

22

18 23

2.5 4 6 10 16

36 47 60 82 109

30 40 51 69 92

30 40 51 68 89

27 35 44 59 78

21 28

25 35 50 70 95

142 174 215 264 317

120 147 182 223 267

116

101

-

120 150 185 240

364 416 472 552

308 352 399 466

-

-

--

-

-

~

-

-

-

. -

-

i) For single-core cables, the sheaths of the circuit are assumed to be connected together at both ends. _

_;_;_LJ:"o1O._bM"~le...~ch..the.iahu1ate,Lv:atues....shollld.htunultinliedJ)JlJl9.~

-

-

-

-

-

56

77

~

331

377 426 496

)i

ELECTRICAL INSTALLATION OF BUILDINGS·

c) rigid metal conduit, except where used underground or in any location where material having a deteriorating effect may come into contact with the metal, or in any exposed raceway installed outdoors where it may be subject to mechanical damage from vehicular traffic, in which case a separate conductor as required in (a) above shall be installed within the conduit; d) electrical metallic tubing, except where used in concrete or masonry slabs in contact with the ground or in any location where material having a deteriorating effect may come into contact with the metal, or in any exposed raceway installed outdoors where it may be subject to mechanical damage from vehicular traffic, in which case, separate conductor as required in (a) above shall be installed within-the tubing; e) the sheath of mineral-insulated cable, except when it is stainless steel, or any conductor of a mineral-insulated cable if it is permanently marked at the time of installation 80 that it can be readily distinguished from conductors that are not used as bonding conductors, except that if the sheath is of aluminium in an underground run or in a location where materials having a deteriorating effect may come in contact with the metal, corrosion resistant protection suitable for the corrosive condition encountered shall be provided; f) the sheath of aluminium-sheathed cable, but if used for underground runs or in locations where materials having a deteriorating effect may come in contact with the metal, corrosion-resistant protection suitable for the corrosive conditions encountered shall be provided; or g) . other metal raceways or cable armour as provided for in Clause 7.6.6.

7.9.2

Installation of Earthing Conductors for a System

(l) The earthing conductor for a system shall be without joint or splice throughout its length, except in the case of bus bars, thermit welded joints, compression connectors applied with a compression tool compatible with the particular connector, or devices acceptable for connection in series with the earthing conductor. (2) 16.0mm 2 or larger copper earthiIig conductor which is free from exposure to mechanical injury may be run along the surface of the building construction without metal covering or protection, if it is rigidly stapled to the construction; o.therwise, it shall be in conduit, electrical metallic tubing or cable armour.


EBCS-10 1995

172

SECTION 7: EARTHING, BONDING AND LIGHTENING PROTECTION

7.8.3.7

Connection of electrodes

(l) Where separation of the different system electrodes is not possible, the electrodes shall be connected together, at or below ground level, with a copper conductor of a size not less than that of the earthing conductor for the electrical system and in no case shall the conductor be smaller than 16.0mm2 copper.

7.8.3.8

Bonding

(l) Where any or all of the separate earthing electrodes are bonded together the bonding . conductor shall be:

a) a copper conductor not smaller than 16.0mm2 ; b) installed so as not to be subjected to mechanical damage; and c) connected to electrodes for power systems by means of a bolted clamp or soldered joints and preferably be connected to other electrodes in the same manner.

7.9

EARTHING AND BONDING CONDUCTORS

7.9.1

General

7.9.1.1

Continuity of earthing and bonding conductors

(l) No automatic cutout or switch shall be placed in the earthing or bonding conductor of a wiring system unless the opening of the cutout or switch disconnects all sources of energy.

7.9.1.2

Material for system earthing

(l) The eartliing conductor of a wiring system, whether also used for earthing electrical equipment or not, may be insulated or bare, and shall be of copper.

7.9.1.3

Material for bonding conductors

(1) The earthing conductor of a wiring system, whether also used for earthing electrical equipment or not, may be insulated or bare, and shall be: ~

a) a conductor of copper or other corrosion-resistant material, insulated or bare;

b) a bus bar or steel pipe; _

171

EBCS-10 1995


--_._ ..

-

_.----"


, 7.8.3.2

Rod electrode

(1) A rod electrode shall:

'.

a) be not less than I6.0mm in diameter if of iron or steel, or I2.7mm if non-ferrous metal or ferrous metal clad with a non-ferrous metal; b) be not less than 3.0m in length; . c) have a' clean metal surface which is not covered with paint, enamel, or other poor conducting material; and

d) be spaced not less than 3.0m apart (if more than two rods are required).

7.8.3.3

Plate electrode .

(1) Plate electrode shall present not, less than O.2m2 of surface to exterior soil and be not less than 6.35mm in thickness if of iron or steel, or I.5mm if of ferrous metal.

7.8.3.4

Laying

(1) An artificial earthing electrode shall be buried: , . a) at least 250.0mm below permanent moisture level as far as practical; b) in a horizo,ntal trench where rock bottom is encountered at depth less than 102m.

7.8.3.5

Driving rod electrode

(1) A rod electrode shall be driven to a depth of no less than 3.0m regardless of the size or number used, except that:

. a) where rock bottom is encountered at a depth of I.2m or more, it shall be driven to rock bottom; or b) where rock bottom is encountered at a depth of less than 1.2m, it shall be buried in a horizontal trench and be not less 3.0m long.

7.8.3.6

Spacing

(1) Each electrode shall be separated at least 2.0m from any other electrode including an electrode used for signal circuits, radio, lightning, or any other purpose.


EBC~10 1995

170

---

~------_._-----

-"

._-----------------~------------

--

-

--"

._-_.,-.--_._----_.- --'------"


7.8.2.3

Metal casing of a pump

(1) Where a metal casing of a pump system is used as earthing electrode, it shall not be less than 75.0mm in diameter and shall extend at least 15.0m below the well-head.

7.8.2.4

Bonding

(1) Where more than one of the earthing means listed under Clause 7.8.2 exist at a building, they shall be bonded together with a conductor complying with Clause 7.5.4(3).

7.8.3

Artificial Earthing Electrodes

7.8.3.1

Concrete-Encased Electrode

(1) A concrete-encased electrode shall be encased within the bottom 50.0mm of a concrete foundation footing that is in direct contact with the ground and shall be: a) a bare copper conductor not less than 6.0m in length and of size specified in Table 7.2, or b) a plate electrode that shall: i) present not less 0.4m2 of surface to the concrete encasing the plate; ii) be not less than 6.0mm in thickness if of iron or steel; or i .5mm in thickness if non-ferrous metal; and iii) have a means of attachment for' the system earthing conductor that shall be accessible after the concrete is poured.

Table 7.2 Minimum size for concrete encased electrodes

169

Ampacity of largest associated circuit conductor [A]

Size of copper conductor [(mm 2]

160 or less 161 - 250 251 - 335 356 - 500 above 500

25 35 50 70 95

EBCS-10 1995


---- .• - .. _-------

-------~-----------------_._-----


a) They shall be copper or other corrosion-resistant material. b) They shall be of sufficient size to have an ampacity not less than that required for the corresponding earthing conductor. c) They shall be attached to cabinets and similar equipment in a manner specified in Clause 7.10.4. d) They shall be straps when used for bonding non-current-carrying metal parts; shall not be less than 19.0mm in width and not less than.: i) 1.rlmm in thickness if of steel; or ii) 1.2mm in thickness if of aluminium or copper.

7.8

EARTIDNG ELECTRODES

7.8.1

General

(I) The type and embedded depth of an earth electrode shall be such that the drying and freezing of soil will not increase its resistance above the required value. (2) The design used in and the construction of an earth electrode shall be such as-to withstand damage and to take account of possible increase in resistance due to corrosion.

7.8.2

Service Pipe Electrode

7.8.2.1

Public water pipe

(1) Where a service water pipe from a public water main to a building is used as earthing electrode, it shall be:

a) continuously conductive; b) located or placed underground not less than 250.0mm below the normal pennanent moisture level; and c) the underground portion extends not less than 3.0m beyond the extremities of the building served.

7.8.2.2 Independent metal water pipes (I) Where a conductive independent metal water piping system is used as earthing electrode, it shall be placed underground not less than 250.0mm below the normal permanent moisture level and the underground portion extend not less 3.0m beyond extremities of the building served.


EBCS-10 1995

168


b) the use of threadless couplings made up tight where electrical metallic tubing is used; or c) the use of bonding jumpers meeting the requirements of Clauses 7.7.7 and 7.9, or d) other devices (not standard locknuts and bushings) such as earthing bushings equipped with bonding jumpers meeting the requirements of Clause 7.7.7 below,

7.7.4

Metal Armour or Tape of Service Cable

(l) Where service cable has an uninsulated earthed service conductor in continuous electrical contact with its metal armour or tape, the metal covering shall be considered to be adequately earthed.

7.7.5

Bonding at Other-Than-Service Equipment

(l) The electrical continuity of metal raceway, metal sheathed, or armoured cable shall be assured by one of the methods specified in Clauses 7.7.3 or by the use of: a) threadless fittings, made up tight with conduit or armoured cable; b) two locknuts, one inside and one outside of boxes and cabinets; or c) one locknut and a metal conduit bushing provided the bushing cable installed so that it is mechanically secure and makes positive contact with the inside surface of the box or cabinet.

7.7.6

Loosely Jointed Metal Raceways

(1) Expansion joints and telescoping sections of raceways shall be made electrically continuous by bonding jumpers or other acceptable means. (2) Metal through raceways used in connection with sound recording and reproducting equipment made up in sections shall contain an earthing conductor to which each section shall be bonded.

7.7.7

Bonding Jumpers'

(l) Bonding jumpers shall satisfy the following:

t A bonding jumper is a reliable conductor to assure the required electrical conductivity between metal

parts required to be electrically connected.

167

EBCS-10 1995



(2) The annour of armoured cables incorporating a bonding conductor shali not be considered as fulfilling the requirements of a bonding conductor for the purpose of this Clause, and the bonding conductor provided in these cables shall comply with (lb) above. (3) The armour of flexible metal conduit and liquid-tight flexible metal conduit shall not be considered as fulfilling the requirements of bonding conductor for the purposes of this Clause, and a separate bonding conductor shall be run within the conduit. (4) The sheath of mineral-insulated cable having a stainless steel shall not be considered as fulfilling the requirements of a bonding conductor for the purposes of this Clause and bonding shall be by one of the methods specified in (l b) or (I d) above.

7.7

BONDING METHODS

7.7.1

Clean Surface

(l) Where a non-conductive protective coating such as paint or enamel is used on the equipment,

conduit, couplings or fittings, such coating shall be removed from threads and other contact surfaces in order to ensure a good electrical connection.

7.7.2

Bonding at Service Equipment

(1) The electrical continuity of the earthing circuit at the service equipment shall be assured by one of the means given in Clause 7.7.3 for the following equipment and enclosures if of metal: a) Service raceways or service armour or sheaths. b) All service equipment enclosures containing service entrance conductors including meter fittings, boxes or the like, interposed in the service raceway or armour. c) Any conduit or armour which forms part of the earthing conductor to the service raceway.

7.7.3

Means of Assuring Continuity at Service Equipment

(l) Electrical continuity at service equipment shall be assured by:

a) the use of threaded couplings and threaded bosses on enclosures with joints made up tight rigid metal conduit is used; or


EBCS-10 1995

166

---------------_._----~-------_.----_._.

SECTION 7: EARTHING, BONDING AND L1GHTENIN.G PROTECTION

7.6.4

Underground Service

(1) Where an underground service cable is served from a continuous underground metal sheathed cable system and the sheath or armour of the service cable is connected to the underground system, the sheath or armour of the service cable shall not be required to be bonded to earth at the building' if it is insulated from the interior conduit or piping.

(2) Where a metal-sheathed service cable served from a continuous underground metal sheathed cable system is bonded to the underground system and is contained in an underground service conduit, the conduit shall not be required to be bonded to earth at the building if it is insulated from the interior conduit or piping.

7.6.5

Short Section of Raceway

(1) Isolated section of metal raceway or cable armour, if required to be bonded to earth, shall preferably be bonded so by connecting to other earthed raceway or armour.

7.6.6

Fixed Equipment

(1) Fixed equipment shall be bonded to earth in one of the following ways:

a) An effective metallic connection to earthed metal raceways, metal sheath, or cable armour except: ~

i) Armour as specified in Clauses in '(2) and (3) below; and/or ii) sheath of mineral-insulated cable when of stainless steel as specified in (4) below; and/or iii) where the raceway or cables are run underground, in locations subject to corrosion. b) A bonding conductor which is run with circuit conductors as a part of a cable assembly and which may be uninsulated; but, if provided with an individual covering, the covering shall be finished to show a green colour or a green/yellow combination. c) A separate bonding conductor installed the same as a bonding conductor for conduit and the like. d) Other acceptable means.

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ELECTRICAL INSTALLATION OF BUILDINGS 7.5.5 Extraneous Fixed Metalwork (I) The exposed metal parts of all equipment which is required by this part of the Code to be earthed, which might otherwise come into fortuitous contact 'with extraneous fixed metalwork, shall be either effectively segregated therefrom, or effectually bonded thereto, so as to prevent appreciable voltage differences at such possible points of contact. (2) For sizes of bonding conductors, refer to Table 7.1. Note:

The extraneous fixed metalwork required to be bonded and earthed in these circumstances includes the following: i) Baths and exposed metal pipes, sinks and tanks, in the absence of metal-to-metal joints of negligible electrical resistances. ii) Where practicable, accessible structural steelwork. iii) Framework of mobile equipment, such as cranes and lifts, on which an electrical apparatus is mounted.

7.6

METHOD OF EARTHING

7.6.1

Effective Earthing

(I) The path to earth from circuits, equipment, or conductor enclosures shall be permanent and continuous and shall have: a) sufficient ampacity to conduct safely any current liable to be imposed on it; and b) impedance sufficiently low to limit the voltage above earth, and to facilitate the operation of overcurrent devices in the circuit.

7.6.2 Common Earthing Conductor (I) The earthing conductor for circuits shall be permitted to be used as a bonding conductor for equipment, conduit, and other metal raceways, or enclosure for conductors, including service conduit or cable sheath and service equipment.

7.6.3 Common Earthing Electrode (I) Where the alternating-current system is connected to an earthing electrode in or at building as specified in Clauses 7.4.2, the same electrode may be used to earth conductor enclosures and equipment in or on that building.


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Table 7.1 Minimum sizes of copper-earthing and copper-bonding conductors not contained in a composite cable, flexible cable, or flexible cord

Nominal cross-sectional area of largest associated copper circuit conductor

Nominal cross-sectional area of earthing conductor

Nominal cross-sectional area of bonding coductor

mm"

mm 2

mm"

1.0 1.5 2.5

6 6 6

1.0 t 1.0t 1.0t

4

6 10

6 6 6

1.0t 1.0t 2.5t

16 25 35

6 16 16

2.5 6 6

50 70 95

16 50 50

6 16 16

120 150 185

50 50 70

16 16 50

240 300 400

70 70 70

50 50 50

500 600

70 70

50' 50

t .2.5mm2 for bonding metal workof other services at points of entry to premises.

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I

l

I

/


(2) The bonding conductor shall be attached to the water supply service or gas service: a) at a location as near to consumer's electrical service entrance as is practicable; and b) at a Iocation where a sub-feeder enters a building. (3) The water supply service or the gas service shall be bonded by means of a copper bonding conductor not less than the appropriate value shown in Table 7.1 subject to a minimum size of 2.5mm2 • Note:-

i) For the purpose of Clause 7.,5 the associated circuit conductor is the largest conductor connected into the input side of the consumer's switchgear. ii) Conductor of material other than copper shall have a resistance not exceeding that of the prescribed ._ copper .conductor. iii) Connection to the. pipes of the services shall be made by means of a clamp.


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c): Interrupt the continuity of the conductors between the earthing connections..

d) Take other suitable remedialaction to limit the current.

Note:

The temporary currents which are set up under accidental conditions while the earth conductors are performing their intended protective functions are not considered objectionable.

7.5

BONDING

7.5.1

Non-Current-Carrying Metal Parts

(1) A~I non-current-carrying metal work of wiring systems including cable sheaths and armour.: conduit, ducts, trucking boxes, and catenary wires, shall be bonded to earth. (2) Where isolation of metal is adopted as a protective measure (prevention of dangerous earth leakage current), it shall he confined to the following items: a) . Short isolated lengths of metal used 'for the mechanical protection of cables having a non-metallic sheath.

b) Metal clips used for fixing cables.

c) Small metal parts such as screws, 't"r name-plates isolated by isolating material.

7.5.2 Exposed Non-Current-Carrying Metal Parts of Equipment (1) Exposed non-current-carrying metal parts of equipment shall be bonded to earth; however this does not apply to double-insulated equipment or isolated metal parts referred to in Clause 7.5.1(2).

7.5.3 Non-Metallic Wiring Systems (1) Where nonmetallic wiring systems are used: a) anearth connection shall be provided at all outlets; and b) metal boxes shall be earthed.

'.5.4 .Non-Electrical Services (1) Metal parts of water supply services and gas services which may become enorgized shall be bonded to earth.

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ELECTRICAL INSTALLATION OF BUILDiNGS

a) The earthing conductor shall not be smaller than that specified in Table 7.1. b) Tftwo or more systems are employed, a common system earthing conductor shall be installed unless separate earthing is supplied tor each such system, in which case the earthing rot' the individual systems shall be interconnected.

7.4.4

Single Service Supply to Two or More Buildings or Structures

(1) Where to or more buildings or structures are supplied from a single service: a) the earthed circuit conductor at each of the buildings or structures shall be connected to an earthing electrode and bonded to the non-current-carrying metal parts of the electrical equipment; or b) except for buildings housing livestock, the non-current-carrying metal parts of the electrical equipment in or on the building or structure shall be permitted to be bonded to earth by a bonding conductor run with the feeder or branch circuit conductors.

7.4.5

Conductors to be Earthed.

(1) For a.c, wiring systems, the conductors to be earthed shall be as follows: a) Single-phase, 2-wire, the identified conductor; b) Single-phase, J-wire, the identified neutral conductor; c) Multi-phase systems having one wire common to all phases, the identified neutral conductor; 'd) Multi-phase systems having one earthed phase, the identified conductor; e) Multi-phase systems in which one phase is used as in (b) above, the identified conductor,

7.4.6

Current Over Earthing Conductor ''P'

(1) Where wiring systems, circuits, electrical equipment, cable armour, conduit and other metal . raceways are earthed as a protective measure, the earthing shall be arranged so that there is no objectionable passage of current over the earthing conductor or earthing path.

(2) If the use of multiple earthing connections results in an objectionable flow of current, one or more of the following alterations shall be made: a) Abandon one or more of the earthes,

b) Change the locations of the earthing connections.

ETHIOPIAN BUILDIN(3 CODE STANDARD

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ELECTRICAL INSTALLATION OF BUILDiNGS

a) The earthing conductor shall not be smaller than that specified in Table 7.1. b) Tftwo or more systems are employed, a common system earthing conductor shall be installed unless separate earthing is supplied tor each such system, in which case the earthing rot' the individual systems shall be interconnected.

7.4.4

Single Service Supply to Two or More Buildings or Structures

(1) Where to or more buildings or structures are supplied from a single service: a) the earthed circuit conductor at each of the buildings or structures shall be connected to an earthing electrode and bonded to the non-current-carrying metal parts of the electrical equipment; or b) except for buildings housing livestock, the non-current-carrying metal parts of the electrical equipment in or on the building or structure shall be permitted to be bonded to earth by a bonding conductor run with the feeder or branch circuit conductors.

7.4.5

Conductors to be Earthed.

(1) For a.c, wiring systems, the conductors to be earthed shall be as follows: a) Single-phase, 2-wire, the identified conductor; b) Single-phase, J-wire, the identified neutral conductor; c) Multi-phase systems having one wire common to all phases, the identified neutral conductor; 'd) Multi-phase systems having one earthed phase, the identified conductor; e) Multi-phase systems in which one phase is used as in (b) above, the identified conductor,

7.4.6

Current Over Earthing Conductor ''P'

(1) Where wiring systems, circuits, electrical equipment, cable armour, conduit and other metal . raceways are earthed as a protective measure, the earthing shall be arranged so that there is no objectionable passage of current over the earthing conductor or earthing path.

(2) If the use of multiple earthing connections results in an objectionable flow of current, one or more of the following alterations shall be made: a) Abandon one or more of the earthes,

b) Change the locations of the earthing connections.

ETHIOPIAN BUILDIN(3 CODE STANDARD

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SECTION 7: . EARTH!NG, BONDING AND LIGHTENING P~OTECTION

7.4

LOCATION OF SYSTEM EARTIllNG CONNECTIONS

7.4.1

D.C. Systems

(1) D.C. systems to be earthed shall have the earthing connection made at one or more supply stations; but not at individual services nor elsewhere on interior wiring.

l

)

7.4.2

A.C. Systems

(1) An internal wiring system that is supplied by an a.c. service and which is to be earthed shall have at each service, an earthing conductor connected to an earth electrode which complies with Clause 7.8 below. (2) TIle earthing conductor shall be connected to the earthed service conductor at any accessible point from the load end of service drop or service lateral. (3) Where the transformer supplying the services is located outside the building, at least one additional earthing connection shall be made from the earthed service conductor to an .earth electrode, either .at the transformer or elsewhere.(. outside the building. (4) An earthing connection shall not be made to any earthed circuit conductor on theload side of the service disconnecting means. \

.(5) For circuits that are supplied from two sources in a common enclosure or grouped together in separate enclosure and employing a tie, a single earthing electrode connection to the tie point of the earthed circuit conductors from each power-supply source shall be permitted. (6) Where the system is earthed at any point, the earthed conductor shall be run to each individual service and not be smaller than the required earthing conductor specified in Table 7.1, and where the earthed circuit conductor also serves as the neutral, the requirements of the relevant Clauses of Section 4 shall be met. 7.4.3

Isolated Systems

(I) For a wiring system or circuit which is required to be earthed, and which is not conductively connected to a. distribution system, the earthing connection shall be made at the transformer, or other source of supply, or on the supply side of the first switch controlling the system, and satisfying both the following conditions:

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j I

I i


7.3

SYSTEM AND CIRCUITS EARTHING

7.3.1

Direct Current Systems

;1

(l) A two-wire direct-current system supplying interior wiring and operating at not more than 300.0V or not less than 50.0V between conductors shall be earthed, unless such system is used. for supplying industrial equipment in limited areas and the circuit is equipped with an earth detector.

(2) The neutral conductor of all 3-wire direct-current systems supplying interior wiring shall be earthed. 7.3.2

Alternating Current Systems

(1) Except as otherwise provided for in this Code, alternating-current systems shall be earthed

if: a) by so doing, their maximum voltage-to-earth does not exceed 230.0V; or b) the system incorporates a neutral conductor. ~2) Wiring systems supplied by an unearthed supply shall be equipped with a suitable earth 'detection device to indicate the presence of an earth fault.

(3) Circuits of less than 50.0V shall be earthed under any of the following conditions: a) Where supplied by transformers that are energized from: i) systems of more than 230.0V-to-earth; or ii) unearthed system.

b) Where installed as overhead outside of buildings.

(4) Where primary windings of current. and voltage instrument transformers are connected to circuits of 230.0V-or-more-to-earth, the secondary circuits of the transformer shall be earthed. (5) Where the transformers are on switchboards, the secondary circuits shall be earthed irrespective of the voltage of the circuits.


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_." - -----_.-..........:.----------_.

-_._-'--~-.---_.

. - - - - " " . _ - - -"-------'---.

,

.--

- --_.....:.- --_ ..._~_.~---_.- _ . _ - ' .. -_._-------'----------:...---_._-

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I 7.3

SYSTEM AND CIRCUITS EARTHING

7.3.1

Direct Current Systems

(1) A two-wire direct-current system supplying interior wiring and operating at not more than 300.0V or not less than 50.0V between conductors shall be earthed, unless such system is used for supplying industrial equipment in limited areas and the circuit is equipped with an earth detector.

(2) The neutral conductor of all 3-wire direct-current systems supplying interior wiring shall be earthed. 7.3.2

Alternating Current Systems

(1) Except as otherwise provided for in this Code, alternating-current systems shall be earthed if:

a) by so doing, their maximum voltage-to-earth does not exceed 230.0V; or b) the system incorporates a neutral conductor. (2) Wiring systems supplied by an unearthed supply shall be equipped with a. suitable earth .'detection device to indicate the presence of an earth fault. (

(3) Circuits of less than 50.0V shall be earthed under any of the following conditions: a) Where supplied by transformers that are energized from: i) systems of more than 230.0V-to-earth; or ii) unearthed system.

b) Where installed as overhead outside of buildings.

(4) Where primary windings of current and voltage instrument transformers are connected to circuits of 230.0V-or-rnore-to-earth, the secondary circuits of the transformer shall be earthed. (5) Where the transformers are on switchboards, the secondary circuits shall be earthed irrespective of the voltage of the circuits.


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- "-

- - " - - '- - - - - - - - - - - - _ . : . - _ - - - - - - " - - - " - - '

----.-

.---_._.-'-------

...:_------

SECTION

7

EARTIllNG, BONDING, AND LIGHTNING PROTECTION"

PART I - EARTHING AND BONDING 7.1

SCOPE

(1) Part I of this Section covers the protection of electrical installation by earthing and bonding. (2) This part also covers provisions for insulating and guarding as suitable alternatives to earthing where permitted by this Code.

7.2


(1) The following references contain provisions which, through reference in this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings. (a) C22.1:1992

Canadian Electrical Code, Part 1, Safety Standard for Electrical Installations, Sixteenth Edition.

(b) NFPA 70/NEC:1987

An American National Electrical Code.

(c) IEE:1970

The Institute of Electrical Engineers, Regulations for the Electrical Equipment of Buildings, Fourteenth Edition, Incorporating Amendments.

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r-~-~~~··--~··_·

I \'

I

-----

..

_0

_

-----

---_._--_._-,---~~-

ELECTRICAL INSTALu\TION OF BUIL.DINGS

, Table 6.1 Demand factor for service and feeders and watts per square meter-for various types of occupancy

Demand factor [%] Watts per m

Type of Occupancy

2

Service conductor

Feeders 100

Store, Restaurant

30

100

Office

50

70-90

Industrial and Commercial

25

100

I Mosque

10

100

Church

I

qO 100 100

I

Garage

10

100

Storage warehouse

5

70

90

Theatre

30

75

95

Armouries arid Auditoriums

1Q

80

100

Banks

50

100

100

Barber shops and beauty parlors

30

90

100

Clubs

20

80

100

Court houses

20

70

90

Loadges

15

80

100

100.

Table 6.2 Feeder demand factors for lifts

Number of lifts on a single feeder 1

Demand factors (OF)

Number of lifts on a single feeder

1.00

6

Demand factors (OF) 0.79 I

I

2

0.95

3

7

O.T!

0.90

8

0.75

4

0.85

9

0.73

5

0.82

10 or more

0.72

I

Note: Demand factors (DF) are based on 50% duty (i.e, half-time load, half-time no load).


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SECTION 6: CIRCUIT LOADING AND DEMAND FACTOR

6.5.6 Other Types of Occupancy (1) The minimum ampacity of service of feeder conductors for the types of occupancies specified in Table 6.1 shall be based on the following:

(a) a basic load to be calculated on the basis of watts per square meter required by Table 6.1 for the area served based on the outside dimensions, with application of demand factors as indicated therein; plus (b) special loads such as air conditioning, power loads, show window lighting, stage lighting, etc, based on the rating of the equipment installed with such demand factors as are permitted by this Code. 6.5.7 Branch Circuits (1) Conductors of a branch circuit supplying "Injera Mitad" and/or cooking stove in a dwelling unit shall be considered as having a demand of

(a) 3.5kW for "Injera Mitad"; (b) 8.0kW where the rating of the cooking stove does not exceed 12.0kW; or (c) 8.0kW plus 40% of the amount that the rating of the cooking stove exceeds 12.0kW. Note:

For the purpose of Clause 6.5.7(1), two or more separate built-in cooking units may be considered as one cooking

(2) For "Injera Mitad" and or a cooking stove installed in commercial, industrial, and institutional establishments, the demand shall be considered as not being less than the rating. (3) The demand loads given in (I) above shall not apply to cord-connected hotplates or other appliances. 6.5.8 Feeder Demand Factors for Lifts (1) Feeder demand factors for lifts shall be as shown in Table 6.2.

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(2) Demand factors may be applied as follows: (a) 80% for abuilding with an area upto and including 900.0m 2 based on the outside dimensions; (b) For a building with an area exceeding 900.0m based on the outside dimensions, the . balance of the load may be divided by the number of square meters to obtain a load-per square-meter rating and the demand load may be considered to be the sum of: i) 80% of the load per square meter multiplied by 900; and ii) .65% of the load per square meter multiplied by the area of the building in excess of . 900.0m 2•

6.5.5

Hotels, Motels, Dormitories, and Buildings of Similar Occupancy

(1) The minimum ampacity of service or feeder conductors shall be based on the following: (a) a basic load of 20.0W/m 2 of the area of the building based on the outside dimensions; plus (b) lighting loads for special areas such as ballrooms, based on the rating of the equipment installed; plus (c) air conditioning and power loads based on the rating of the equipment installed. (2) Demand factors may be applied as follows: a) 80% for a building with an area upto and including 900.0m 2 based on the outside dimensions; b) For a building with an area exceeding 900.Om2 based on the outside dimensions, the balance of the load may be divided by the number of square meters to obtain a load-per square meter rating and the demand load may be considered to be the sum of: i) 80% of the load per square meter multiplied by 900; and ii) 65% of the load per square meter multiplied by the area of the building in excess of 900.0m 2•


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SECTION 6: CIRC.UIT LOADING AND DEMAND FACTOR

(b) If air-conditioning is used, the amount by which the sum of all the air-conditioning loads exceeds 1500.0VA shall be added, With a demand factor of 100%, to the load determined : in accordance with (a) above. (0) In addition, any lighting, heating, and power loads not located in dwelling units shall be

added with a demand factor of 75%. Note:

The livingarea designated in Clause 6.5.1 and6.5.2shall be determined from the outside dimensions of the group floor of the dwelling plus 75% of the basement area basedon the inside dimensions, plus any area which might nonnaUy be used for living purposes on the upper floors,

6.5.3 Schools (1) The minimum ampacity of service or feeder conductors shall be based on the following: a) a basic load of 50.0W/m2 of classroom area; plus b) 10.OW/m2 of the remaining area of the building based on the outside dimensions; plus c) air conditioning, and power loads based on the rating of the installed equipment. (2) Demand factors may be applied as follows: (a) 75% for abuilding with an area upto and including 900.0m2 based on the outside dimensions. (b) For a building with an area exceeding 900.0m 2based on the outside dimensions, the load may.be divided by the number of square meters to obtain a load-pre-square-meter rating and the! demand load may be considered to be the surri of: i) 75% of the load per square meter multiplied by 900; and ii) 50% of the load per square meter multiplied by the area of the building in excess of 900.0m 2 •

6.5.4 Hospitals (I) The minimum ampacity of service or feeder conductors shall be based on the following:

(a) a basic load of 20.0W/m 2 of the area of the'.building based on the outside dimensions; plus . (b) 100.OW/m2 for high intensity area such as operating rooms; plus (c) air conditioning, and power loads based on the rating of the installed equipment

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--------_._----

..

-.--------_._--'--~ _--~-----_._--------~._-----_

.._~--_.

ELECTRICAL INSTALLATION OF BUILDINGS (a) a basic load of 2500.0W for the first 70.0m 2 of living area; plus (b) an additionallOOO.OW for each 70.0m 2or portion thereof in excess of 70.0m 2; plus (c) 3500.0W for any electric "Injera Mitad"; plus (d) 6000.0W for a single cooking stove having a rating of 12.0kW or less, plus 40% of the amount by which the rating of the cooking stove exceeds 12.0kW; plus (e) any electric water heater with a demand factor of 100%.

6.5.2 Apartment and Similar Multi-Family Buildings (1) The minimum ampacity of service or feeder conductors from a main service supplying-loads in dwelling units shall be based on the following:

(a) a basic load of 2500.0W for the first 45.0m 2 of living area; plus (b) an additional 1500.0W for the second 45.0m 2 or portion thereof; plus (c) an additional lOOO.OW for each additional 90.0m 2 or portion thereof in excess of the initial 90.0m 2; plus (d) 3500.0W for any electric "Injera Mitad"; plus (e) 6000.0W for a single cooking stove having a rating of 12.0kW or less, plus 40% of the amount by which the rating of the cooking store exceeds 12.0kW; plus (f) any electric water heaters with a demand of 100% (2) The minimum ampacity of service or feeder conductors from a main service supplying two or more dwelling units shall be based on the calculated load obtained from Clause 6.5.2(1) and the following: (a) Excluding any air-conditioning loads, the load shall be considered to be: 100% of the calculated load in the unit having the heaviest load; plus 65% of the sum of the calculated loads in the next 2 units having the same or next smaller load to those specified in (i) above; plus iii) 40% of the sum of the calculated loads in the next 2 units having the same or next smaller loads to those specified in (i) above; plus iv) 25% of the sum of the calculated loads in the next 15 units having the same or next smaller loads to those specified in (i) above; plus v) 10% of the sum of the calculated loads in the remaining units;

i) ii)


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--~-_.~-_._-----_ .....

_._'-----

-_._-~

SECTION 6: CIRCUIT LOADING AND DEMAND FACTOR

6.4 .

GENERAL

6.4.1

Current Calculation

(1) When calculating the currents from loads expressed in watts or volt-amperes, to be supplied by a low voltage a.c. system, the voltage divisor to be used shall be 230.0V or 380.0V as applicable.

6.4.2

Voltage Drop

(1) Voltage drop in an installation shall be based upon the calculated demand load of the branch circuits and shall satisfy the requirements of Clause 4.5.4.

6.4.3

Maximum Circuit Loading

For loads other than motors, the total load on consumer's service, feeder or a branch circuit shall be 80% of the circuit rating when the load is a continuous one-,

6.4.4

Use of Demand Factor

(1) Where two or more loads are so installed that only one can be used at anyone time, the one providing the greatest demand shall be used in determining the calculated demand.

(2) Where a feeder supplies loads of a cyclic or similar nature such that the maximum connected .load will not be supplied at the same time, the ampacity of the feeder conductors shall be based 'on the maximum load that may be connected at anyone time. .·(3) The ampacity of conductors of a feeder or branch circuit shall not exceed the ampacity of the .conductors ofthe service or of the feeder from which they are supplied.

6.5

SERVICES AND FEEDERS

6.5.1

Single-Family Dwellings

(1) The minimum ampacity of service or feeder conductors supplying a single-family dwelling shall be based on the following:

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EBCS-10 1995

ETHIOPIAN 8UILDING CODE STANDARD

1------------- I

I

I \ i

SECTION

6:

CIRCUIT LOADING AND DEMAND FACTOR

6.1

SCOPE

(1) This _section covers conductor ampacities and equipment ratings required for consumer's services, feeders and branch circuits.

6.2


(1) The following references contain provisions which, through reference in this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings.: (a) C22.1: 1990

Canadian Electrical Code, Safety Standard for Electrical Installations Sixteenth Edition.

(b) NEC Hand book 1981

6.3

National Electrical Code Handbook Based on the 1981 (NEC), Seventeenth Edition.

DEFINITIONS

(1) For the purpose of this Section, the followingdefmitions shall apply in addition to the terms defined in Section 1.

demand factor

it is the ratio of the maximum demand of a system or part of a system, to the total connected load on the system, to the maximum demand of the whole system,or part of a system, under consideration.

diversity factor

the ratio of the sum of the individual maximum demands of the various subdivisions of a system, or part of a system, to the maximum demand of the whole system, or part of a-system, und~r consideration.

continuous load

any condition in which the maximum load current in a circuit flows without interruption for a period of not less than 3.0hrs.


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__. ----

SECTION 5: SERVICE AND SERVICE EQUIPMENT

(f) Any other suitable type cable (g) Service entrance cable, provided.that:

i) ii) iii) iv)

it is protected by an acceptable means if within 2.0m of the ground; the voltage does not exceed 230.0V to earth; it is supported at intervals not more than l.Om; and it is mounted on insulating supports which hold it not less than 500.0mm from a conductirig surface, if adjacent to such a surface.

(2) Bare overhead supply conductors running on the outside walls of a building may be run as exposed wiring using types of conductor suitable for exposure to the weather. .(3) The length of consumer's service conductors beyond the service head shall be adequate to

enable connection to the supply service conductors or to the conductors referred to in·5.6.2. with a minimum length of 750.0mm. (4) Consumer's service conductors shall be provided with drip loops.

(5) Consumer's service conductors shall be suitable for the temperature which can be experienced in the particular locality. 5.7

METERING EQUIPMENT

5.7.1

Connection

(1) Metering equipment shall be connected on the load side of the service box except that it may . . be connected on the supply where: ,

(a) no live parts or wiring are exposed; (b) the voltage does not exceed 380.0V between conductors; and (c) the rating of the consumer's service does not exceed: i) 200.0A for a meter mounting device, or'

ii) 600.0A for transformer rated meter mounting device located outdoors.

Notei-

149

Transfonnerrated meter mounting device means a meter mounting device with current transformers and with or without test switches mounted in the same enclosure:

EBCS-10 1995



5.6

WIRING METHODS

5.6.1

Underground Consumer's Service Conductors

5.6.1.1

Installation and type

(1) A consumer's service conductors running underground to a building from an underground supply system or from a pole line shall be: (a) installed in rigid conduit and be of a type suitable for use in wet locations; (b) a single or multiple conductor cable for service entrance use below ground provided that: i) ii)

The installation is in accordance with Section 8; Rigid conduit is used for mechanical protection where portions are exposed to injury; and iii) The cable is without splice or joint from a point of connection at the supply service to the consumer's service equipment in the building. •

5.6.1.2

I

Conduit to drain

(1) Consumer's service conduit entering a building underground shall be suitably drained.

5.6.1.3

Conduit seal

(1) Consumer's service conduit connected to an underground system shall be sealed with a suitable compound to prevent the entrance of moisture or gases.

5.6.2

Overhead Consumer's Service Conductors

(1) Conductors of a consumer's service which is connected to an overhead supply service at any point above ground on a building. or other structure shall be installed in a rigid metal conduit or in one of the following ways, if acceptable: (a) (b) (c) (d) (e)

Other type' of rigid conduit, Busway Flexible metal conduit, the conductors being lead-sheathed cable Mineral-insulated cable other than the lightweight type Aluminium sheathed cable


EBCS-10 1995

148


5.5.2.5

Sequence of control

(1) The sequence of the equipment forming the switchgear required by 5.5.2.1 shall be such that the means of disconnect follows the consumer's terminal without the intervention of any other apparatus (see Figure 5.1).

·~~;Db

. III

.

~Lr-G

f~

[Db I I II I

p'a1rams lIIullrallnl seq... nce or protecll"" devices In IY~ical dOmeolle nltallaUonL ("Tha IUPPIY undertaklnl" equip-At and I ' 'wltehFu , .. lneluded,) ..-. a conlumar, FLI ServIc:e ruse and ..... t..lllnk. Jrany.

Wh WaUI·hour meter and/or time switch where requIred ror olr-k IariIr

IUppy. ~ S Consumer', linked 'wllch. FI.Z CoNumcr', main r...,: CB ~:,uma.·, linked Clltal
Figure 5.1 .Sequence of control Note:

5.5.2.6.

The consumer's linked switch and the consumer's main fuse maybe combined in a switch and fuse unit

Detached building

(1) Where .~ consumer's installation comprises installation in two or more buildings, separate means of disconnect complying with the requirements of 5.5.2.2 shall be provided in each building.

5.5.2.7

Capacity ofprotective gear

(l) Every means ofovercurrent protection shall be suitable for the maximum short-circuit current attainable or available.

5.5.2.8

Discrimination

(1) The characteristics and settings of overcurrent protective gear, including fuses, and the arrangement of the installation shall be such that discrimination in the operation of the overcurrent protective gear is ensured.

147

EBCS-10 1995


-----_._----


(c) means of earth-leakage protection (if necessary), Note:

5.5.2.2

Where the Supply Authority provides switchgear and permits part of it.to be used by the consumer, the consumer need not then duplicate that part.

Means 0/ disconnect

(1) The means of disconnect required by 5.5.2.1 shall comprise a linked switch suitable for operation on load or a linked circuit breaker, arranged to disconnect all circuit.

(2) Alternatively, for systems where one conductor is connected with earth, the linked switch or circuit-breaker may be arranged to disconnect the live conductors only and an isolating link may be inserted in the earthed conductor; such an isolating link shall be so arranged that it is in contact before the linked switch can be closed, or shall be securely fixed.by bolts or screws.

5.5.2.3

Overcurrentprotection

(1) The means of overcurrent protection referred to in 5.5.2.1 shall comprise either a fuse inserted in each live conductor of the supply or a circuit-breaker having an overcurrent release fitted in each live conductor of the supply. Exemption: The means of overcurrent protection may be omitted provided that

i) the rating of all cables connected between the Supply Authority's fuse or circuit-breaker and the consumer's sub-circuit fuse or circuit breakers is not less than the rating of the Supply Authority's fuse or circuit breaker; and ii) the overcurrent device protecting all circuits controlled by the switchgear are located within the same enclosure as the switchgear or, alternatively, are fixed immediately adjacent to it.

5.5.2.4

Earth-leakage protection

.

(1) Means for earth-leakage protection shall .be provided for service equipment in accordance with Clause 9.4.2, Section 9. Note: When an installation is being planned, it is desirable to consult the Supply Authority, or a competent person having knowledge of local conditions, to ascertain whether satisfactory protection against earth leakage will be obtained by the use of the fuses or circuit breakers provided.for overcurrent protection or by the use of earth-leakage circuit breaker.


EBCS-10 1995

146

I

I I

I -1.


5.5.1.3

Available short-circuit current

(1) Service equipment shall be suitable for the short-circuit current available at its supply terminal. 5.5.1.4

Working space

(1) Sufficient working space shall be provided to the vicinity of the service equipment to permit safe operation, inspection, and repairs.

5.5.1.5

Location

(1) Service boxes or other consumer's service equipment shall be installed in an acceptable location and in compliance with applicable Codes or Standards or by-laws of the Supply Authority concerning the location of service boxes or other equipment and shall be: (a) readily accessible or have the means of operation readily accessible; (b) not located in coal bine, clothes closets, bathrooms, stairways, rooms in which the temperature normally exceeds 30°C, dangerous or hazardous locations, in locations where the headroom clearance is less than 2.0m, nor in any similar undesirable locations; and (c) placed within the building being served, unless environmental conditions within the structure are unsuitable, in which case the service box or other consumer's service equipment may be placed on the outside of the building or on a pole and shall be: i) protected from the weather, or be weatherproof; ii) protected from mechanical injury if less than 2.0m above ground; iii) placed as close as practical to the point where the consumer's service conductors enter the building. 5.5.2

5.5.2.1

Control

(1) Every consumer's installation shall be adequately controlled by switchgear readily accessible .to the consumer and which shall incorporate: (a) means of disconnect, (b) means of overcurrent protection,

145

's,

EBCS-10 1995



5.4.4

Other Conductors in Raceway or Cable

.(1) Conductors other than service conductors shall not be installed in the same service'way or service-entrance cable.

Exemption:

5.4.5

Earthing conductors and load management control conductor having overcurrent protection.

Clearance from Building Openings

(1) Service conductors installed as open conductors or multi conductor cable without an overall outer jacket shall have a clearance of not less than 925.0mm from windows, doors, porches, fire escape, or similar locations. (2) Service conductors shall not be installed beneath openings through which materials may be moved, such as openings in farm and commercial buildings. (3) Overhead wire shall not be run such that they obstruct entrance to these building openings. Exemption: Conductors running above the top level of a window shall be permitted for a clearance of requirements of less than 925.0mm as in (1) above.

5.5

SERVICE EQUIPMENT

5.5.1

General

5.5.1.1

Enclosed or guarded live parts

(1) Service equipment's live parts shall be enclosed or guarded as specified below: (a) They shall be enclosed so that theywill not be exposed to accidental contact; or (b) If not enclosed they shall be installed on a switch board, panel board, or control board and guarded by providing a means for locking or sealing doors giving access to them.

5.5.1.2

Earthing and bonding

(1) Service equipment, raceway, cable armour, cable sheaths, panel boards, etc and any service conductors that are to be earthed shall be done in accordance with the relevant Parts of Section 7.


EBCS"10 1995

144


. i) ii)

the load requirements are in excess of 3000.0A at a voltage supply of 600.0V· or less; the load requirements of a single-phase installation are greater than that normally supplied through one service.

(c) For fire pumps where a separate service is required. (d) For emergency, legally required standby, optional standby, or parallel power production systems where a separate service is required. .

.

(e) For different characteristics, such as for different voltage, frequencies or phase, or for different uses, such as different rate schedules.

5.4.1.3

~arking

(l) Where more than one service is permitted or provided, a penn anent plaque or directory shall be installed adjacent each service equipment location denoting all other services on or in the consumers' installation and the area served by each.

5.4.1.4

Grouping

(1) When two or more supply services are installed to a building, all service boxes associated with the various consumer's services shall be grouped, where practicable.

5.4.2

Consumer's Installation Not to be Supplied Through Another Building

(1) Service conductors supplying a consumer's installation shall not pass through the interior of another building or other structure.

5.4.3

Conductors Considered Outside of a Building

(1) Conductors shall be considered outside of building or other structure under any of the following conditions; (a) Where installed under not less than 50.0mm of concrete beneath a building or other structure; and (b) Where installed within a building or other structure in a raceway that is enclosed by concrete or brick not less than 50.0mm thick.

w

143

EBC5-10 1995

ETHIOPIAN BUILDING CODE STANDARD·


service drop

the overhead service conductors from the last pole or other aerial support to and including the splice, if any, connecting to the service-entrance conductors at the building or other structure.

service-entrance conductors, overhead system the service conductors between the terminals of the service equipment and a point usually outside the building, clear of building walls, where joined by tap or splice to the service drop. service-entrance conductors, underground system the underground service conductors between the terminals of the service equipment and the last point of connection to the service entrance conductors. Note:

Where service equipment is located outside the building walls, there may be no service-entrance conductors, or they may be entirely outside the building.

consumer's installations wiring and apparatus situated upon the consumer's premises installed and controlled by him, excluding any switchgear of the Supply Authority which the consumer may be permitted' to use. 5.4

GENERAL REQUIREMENTS

5.4.1

Number of Services Permitted

5.4.1.1

Single service

(1) Except as provided in 5.4.1.2..each consumer's installation shall be supplied with a single service.

5.4.1.2

Multiple services

Unless prohibited by Code or Standard or by regulations of the Supply Authority concerning the number of services, additional services shall be permitted in the following cases: (a) In multiple-occupancy building, by special permission, where there is no available space . for service equipment accessible to all the occupants. (b) Due to capacity requirements, two or more services shall be permitted where:


EBCS-10 1995

142

SECTION

5

SERVICE AND SERVICE EQUIPMENT

5.1

SCOPE

(1) This, Section covers services, service equipment, and metering equipment and their installation requirements for systems operating at 1000.0V or less.

5.2


(1) The following references contain provisions which, through reference in this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings. (a) C22.l:1992

Canadian Electrical Code Part 1, Safety Standard for Electrical Installations, Sixteenth Edition

(b) NFPA 701NEC: 1986 National Fire Protection Association!AmericanNationalElectrical Code, 1987 Edition (c) IEE:1970

5.3

The Institute of Electrical Engineers, Regulations for the Electrical Requirements of Buildings, Fourteenth Edition Incorporating Amendments

DEFINITIONS

(1) For the purpose of this Section, in addition to the terms defined in Section 1, the following defmitions shall apply.

service conductors / cable

141

EBCS-10 1995

the supply conductors/cable that extend from the street main or from transformers to the service equipment of the consumer's installation.



Table B.46 Voltage drop (per ampere per metre) Conductor operating temperature: 90°C Conduct or crosssectional area

Two-core cable d.c.


1

2

3

4

mm"

mV

mV

mV

16

4.8

4.8

4.2

x

r

140

25 35 50 70 95

3.1 2.2 1.60 1.10 0.82

120 150 185 240 300

;,

-

.-

EBCS-10 1995

Three or four-core cable, . three-phase a.c.

3.1 2.2 1.65 1.10 0.82

. . .

-

.

.

0.165 0.160 9.160 0.155 0.150

-

-

.

-

-

.

z 3.10 2.20 1.65 1.15 0.84

. .

-

. .

.

r

x

z

2..7 1.90 1.40 0.96 0.71

0.140 0.140 0.135 0.135 0.130

2.7 1.95 1.45 0.97 0.72·

0.56 0.45 0.37 0.28 0.23

0.130 0.130 0.130 0.125 0.125

0.58' 0.47 0.39 0.31 0.26



Table B.45 Multicore armoured cables having thermosetting insulation (aluminium conductor)

Current-carrying capacity (Amperes):

Conducto r crosssectional area

Ambient temperature: 30°C Conductor operating temperature: 900C



1 two-core cable single-phase a.c. or d.c.

1 three- or four cor.e cable, three-phase a.c.

1 two-core cable, single-phase a.c.

1 three- or four core cable three· phase a.c,

2

3

4

5

A

A

A

A

16

82

71

85

74

25 35

50 70 95

1'08 132 159 201 242

92 113 137 174 214

112 138 166 211 254

98

120 145 185 224

120 150

185

240

300

-

249 284 328 386 441

. -

264

305

356

418

488

1

mm

2

.

Note: i) Where the conductor is to be protected by a semi-enclosed fuse, see A.6.2 of the Preface to this Annex. ii) Where a 'conductor operates at a temperature exceeding 7(J'C, it shall be ascertained that the

equipment connected to the conductor is suitable for the conductor operating temperature.


EBCS-10 1995

139

~

~

Table B.44 Voltage drop (per ampere per meter) Conductor operating temperature: 9()Oc 2 Cables - single-phase a.c. Conductor crosssectional area

2 cables d.c.

mm 2

mV

3 or 4 cablea- three-phase a.c.



Reference Methods 1, - ,11 and 12 (In trefoil touching)



mV

mV

mV

mV

mV

r

x

z

r

x

z

x

r

z

r

x

z

r

x

z

50 70 95

1.60 1.10 0.82

1.60 1.10 0.83

0.22 0.21· 0.20·

1.60 0.15 0.85

1.60 1.10 0.85

0.30 0.29 0.29

1.60 1.15 0.90

1.40 0.96 0.71

0.185 0.180 0.175

1.40 0.98 0.74

1.40 0.97 0.74

0.26 0.25 0.25

1.40 1.00 0.78

1.35 0.99 0.76

0.34 0.33 0.32

1.40 1.05 0.83

120 150 185 . 240 300

0.66 0.52 0.42· 0.32 0.26

0.66 0.53 0.43 0.34 0.27

0.20 0.195 0.190 0.185 0.185

0.69 0.57 0.47 0.39 0.33

0.69 0.56 0.46 0.37 0.30

0.28 0.28 0.27 0.27 0.26

0.74 0.62 0.54 0.45 ·0.40

0.57 0.46 0.38 0.29 0.24

0.170 0.170 0.165 .0.160 0.160

0.60 0.49 0.41 0.34 0.29

0.60 0.49 0.40 0.32 0.26

0.24 0.24 0.24 0.23 0.23

0.64 0.54 0.47 0.39 0.34

0.63 0.52 0.44 0.35 0.29

0.31 0.30 0.29 0.29

0.70 0.60 0.53 0.46 0.41

0.180 0.175 0.175 0.170 0.160

0.29 0.25 0.24 0.22 0.20

0.26 0.23 0.20 0.190 0.170

0.25 0.25 0.24 0.22 0.21

0.36 0.34 0.31 0.29 0.27

0.195 0.160 0.135 0.120 0.105

0.155 0.155 0.150 0.145 0.140

0.25 0.22 0.20 0.190 0.175

0.23 0.20 0.175 0.165 0.150

0.22 0.21 0.21 0.195 0.180

0.32 0.29 0.27 0.26 0.24

0.27 0.24 0.22 0.21 0.195

0.27 0.26 0.25 0.22 0.195

0.38 0.35 0.33 0.30 0.28

0.190

0.155

0~20

0.25

0.093

0.135

0.165

0.140

0.175

0.22

0.180

0.185

0.26

380 480 600 740 960

0.21 0.160 .0.130 0.105 0.0-80

0.23 0.185 0.160 0.140 0.120

1200

0.064

0.105

0.160

t .: Spacings larger than those specified in Method 12 (see Annex A, Section 8) will result larger voltage drop.

O.SO

Table B.43 Single-core cables having thermosetting insulation, non-magnetic armour (aluminium conductors) Current-carrying capacity (Amperes): Reference Method 1 (clipped direct)

2~ab~30r4

Conduct or cross sectional area

slngle-. phase a.c. or d.c., flat and touching

cables, three-phase a.c., flat and touching

Ambient temperature: 30°C Conductor operating temperature: 900C Reference Method 11 (on a perforated cable tray) 2 cables, single phase a.c. or d.c., flat and touching -

rnm"

A

A

3 or 4 cables three-phase a.c., flat and touching

Reference method 12 (tree air)

2 cables single-phase a,c.

flat spaced


A

A

Horizontal

A

179 228 276

165 209 252

192 244 294

120 150 185 240 300

320 368 419 494 568

291 333 378 443 508

380 480 600 740 960

655 747 836 934 1056

1200

1163

!


Horizontal spaced

Vertical spaced



A

A

A

A

A

216 275 332

197 253 307

215 270 324

192 244 296

162 207 252

357 411

372 424

480

4n

572 666

554 626

343 394 447 523 595

292 337 391 465 540

649 717 780 835 911

625 714 801 897 1014

980

1118

f-----

A

-

50 70 95

2 cables d.c.

f--.

176 222 267

212 269 328

199

340 390 444 521 597

308 352 400 468 536

378 429 490 576 654

358 409 467 549 624

384

·573 642 706 764 838

688 786 880 988 1121

608 685 757 824 911

735 825 909

812 942 1076 1250 1488

780 906 1036

1094

704 790 872 950 1052

1435

639 765 832 890 970

903

1236

990

1187

1141

1715

1658

1043

;

969

254 . 310

441 511

605 701

120~

Note: i) Where the conductor is to be protected by a semi-enclosed fuse, see A6.2 of the Preface to this Annex. ii) Where a conductor operates at a temperature exceeding 7rJlc. it shaD be ascertained that the equipment connected to the conductor is suitable for the

conductor operating temperature.

w

-..J

3 cables trefoil

ELECTA1CALINSTALLATION OF BUILDINGS


Conductor operating temperature: 90°C


Two-core cable d.c.


1

2

3

4

mm 2

mV

mV

mV

18

4.8

4.8

4.2

136

25

35

50

70

95

3.,1 2.2 1.80 1.10 0.82

120

150

185

240

300

-

-

-

-

EBCS-10 1995

r

X'

3.10 2.20 1.85 1.10 0.82

0.185 0.180 0.180 0.155 0.150

-

-

-

-

-

Three or four-core cable, three-phase a.c.

z

r

3.10 2.7 2.20 1.90 1.85 1.40 1.15 0.98 0.84 0.71

-

-

0.58 0.45 0.37 0.28 0.23

X

~

0.140 0.140 0.135 0.135 ' 0.130

2.7 1.95 1.45 0.97 0.72

0.13'0 0.130 0.130 0.125 0.125

0.58 0.47 0.39 0.31 0.28


r

~

I

Table UAt Multicorethennosetting insulated- cables,non~JlImoured (aluminium conductors) Current-carrying capacity (Amperes):

Ambient temperature: 30°C Conductor operating temperature: 90"C

Reference Method 4 (enclosed in an insulated wall, etc.) Conductor cross sectional area

,

Note:

1 two-core cable,single phase a.c. or d.c.

~ Reference

Method 3 ( enclosed in conduit -on a wall or ceiling, or in trunking)


1 three- or four-core cable, threephase a.c.

1 two-core cable, singlephase a.c. or d.c:

1 three- or four-core cable, threephase a.c.

1 two-core cable,single phase a.c. or d.c.

1 three- or four-corecable, tbree-pbase a.c.

1 two-core cable, singlephase a,c, or d.c.

1 thee- or fourcore cable, three-phase a.c.

1

2

3

4

5

6

7

8

9

mm2

A

A

A

-A

A

A

A

A

16

60

55

72

64

84

76

91

77

25 35 50 70 95

78 96 115 145 175

71 87 104 131 157

94 115 138 175 210

84 103 124 156 188

101 126 154 198 241

90 112 136 174 211

108 135 164 211 257

97 120 146 187 227

120 1,50 185 240 300

-

180 206 233 273 313

-

216 240 272 318 364

-

245 283 323 382 440

-

263 304 347 409 471

-

-

-

-

-

I

~ ----

~-

"--_.

-

-

i) Where the conductor is to be protected by a semi-enclosed fuse, see A62 of the Preface to this Annex. ii) Where a conductor operates at -a temperature exceeding 700C, it shall be ascertained that the equipment connected to the conductor is suitable for the conductor operating temperature.

J-J.

-.

Reference Method 11 (on a perforated cable tray), or Reference Method 13 (free air)

------------

, IN

~

Table :8.40 Voltage drop (per ampere per meter) Conductor operating temperature: 900C

, 2 cables - single-phase a.c.

Conductor

scrosssectiOnal

Reference Methods 3 and 4 (enclosed in conduit etc. in or on awall

Reference Methods 1 and 11 (clipped direct or on trays, touching)

2

3

mV

tnV

2 cables d.c.

area

1

mm

2

' ,3 or 4 cables - three-phase a.c.

Reference Method 12 (Spaced t)

Reference Methods 3 and 4 (enclosed in conduit, etc or on a wall)

Reference Methods 1, 11 and 12 (in trefoil)

Reference Methods 1 and 11 (flat and touching)

Reference Method 12 (flat speced')

4

5

e

7

8

9

mV

mV

mV

mV

mV

mV

0

x

z

1.60 1.13 0.82

1.70 0.30 1.17 0.30 0.86 0.29

1.72 1.21 0.91

1.65 0.190 1.66 1.12 0.185 1.14 0.82 0.185 0.84

1.65 1.12 0.82

0.65 0.53 0.42 0.32 0.26

0.68 0.54 0.45 0.34 0.28

0.74 0.61 0.53 0.43 0.38

0.65 0.52 0.43 0.32 0.26

r

50 70 95 120 150 r85 240 300 380 480 600 740 960 1200

0.29 0.28 0.28 0.27 0.27

0.20 0.160 0.130 0.105 0.080

- - - - - - - - -

0.064

-

~

-

.

r

x

z

r

x 0.28 0.27 0.27

z

r

x

x

0.26 1.46 0.26 1.04 0.25 0.79

1.44 0.97 0.71

0.25 0.64 0.24 0.54 0.24 ' 0.45 0.24 0.38 0.23 0.34

0.57 0.155 0.45 0,155 0:36 0.150 0.28 0.150 0.22 0.145

0.67 0.55 0.46 0.36 0.31

0.65 0.27 0.52 0.26 0.42 0.26 0.32 0.26 0.26 0.26

0;70 0.58 0.49 0.41 0.36

0.59 0.48 0.38 0.30 0.25

0.21 0.165 0.170 0.165 0.140 0.160 0.115 0.160 0.092 0.155

0.27 0.23 021 0.19 0.18

0.25 0.21 0.165 0.25 0.135 0.25 0.110 0.25 0.087 0.24

0.33 0.30 0.28 027 0.26

0.20 0.23 0.165 0.23 0.135 0.22

3.24

0.25

-

0.07

r

1.68 ' 1.44 1.15 1.00 0.94 0.75

0.180 0.175 0.175 0.170 0.170

0.079 0.155 0.17

z

-

-

-

0.31 0.28 0.26

z

0.165 1.45 1.44 0.160 0.98 0.97 0.160 0.73 0.71 0.59 0.47 0.39 0.32 0.27

.

0.180 0.150 0.120 0.100 0.082

-

0.070 0.135 0.150

.

x

r

0.145 0.23 0.140 0.20 0.140 0.185 0.1350.170 0.135 0.160

0.24 1.46 0.24 1.00 0.23 '0.57

r

1.44 0.97 0.71

x

z

0.32 1.48 0.31 1.08 0.31 0.78

0.57 0.45 0.36 0.28 0.22

0.23 0.23 0.23 0.22 0.22

0.61 0.57 0.50 0.45 0.43 0.36 0.35 0.28 0.31 ,0.22

0.180 0.150 0.120 0.100 0.082

0.22 0.22 0.22 0.21' 0.21

0.28 0.27 0.25 0.23 0.23

0.180 0.29 0.34 0.145 0.29 0.32 0.120 0.29 0.31 0.095 0.29 0.30 0.076 0.29 0.30

0.22

0.063

0.070 0.21 ~

t Spacings larger than those specified in Method 12 (see Annex A of Section 8) 'Will result in a larger voltage drop.

z

0.31 0.30 0.30 0.30 0.30

0.64 0.54 0 ..4 7 0.41 0.37

0.28 0.29

1--

Table B.39 Single-core thermosetting insulated cables, non-armoured

(aluminium conductors)

.


conductor crosssectional area

.

I!

Note:

,...

IN IN

Reference Method 4 (enclosed in conduit in thermally inSUlating wall etc.)

Ambient temperature: 30°C Conductor operating temperature: 9()OC Reference Method 3 (enclosed in conduit on, a wall or in trunking etc.)


Reference Method 1t (on a perforated cabletray horizontal or vertical

Reference Method 12 (free air) Horizontal f1atspaced

Vertical flat spaced 2 cables,

Trefoil

I


2 cables, singlephase a.c. or d.c. flat and touchinq

3 or 4cables, three-phBfe a.c. flat and touching or trefoil

2 cables, singlephase a.c. or d.c. flat & touching

3 or 4 cables, three-phase a.c. flat and touching or trefoil

2 cables, singlephase a.c. or d.c., or 3 three-phase a.c.

phase a.c. or d.c. or 3 three-phase a.c.

4

5

6

7

8

9

10

11

A

A

A

A

A

A

A

A

A

125 158 191

113 142 171

157 200 242

140 179 217

169 215 265

.149. 189 234

180 231 281

165 211 258

210 271 332

188 244 300

159 206 253 .

120 150 185 240 300

220 253 288 338 387

197 226 256 300 344

281

251

-

-

308 353 410 489 564

273 314 366 438 507

326 376 430 509 586

300 346 396 469 541

387 448 515 611 708

351 408 470 561 652

296 343 395 471 544

380 480 600 740 960

-

-

-

-

-

-

658 765 871 1001 1176

594 692 791 911 1072

679 786 903 1025 1191

628 728 836 951 1108

798 927 1058 1218 1440

742 865 990 1143 1355

638 743 849 979 1151

1200

-

-

-

-

1333

1217

1341

1249

1643

1550

1307

2 cables, single phase a.c. or.d.c,

3 or 4 cables three-phase a.c.

1

2

3

mm"

A

50 70 95

2 cables, singlephase a.c. or d.c.

singl~

i. Where the conductor is to be protected by a semi-enclosed fuse, see A.6.2 of the Preface to this Annex. ii .Where a conductor operates at a temperature exceeding 7IYC, it shall be ascertained that the equipment connected to the conductor is suittable for the conductor operating temperature

I

I

3 cables 'Irefal, three-phase. a.c,

,I

']2

A



Conductor operating temperature: 70°C

Conductor crosssectional area1

Two-core cable d.c.


Three- or four-core cable, three-phase a.c.

1

2

3

4

mrn"

mV

mV

mV

16

4.5

4.5

3.9

25 35 50 70 95

2.9 2.1 1.55 1.05 0.77

120 150 185 240 300

132

EBCS-10 1995

r

x

2.90 2.10 1.55 1.05 0.77

0.175 0.170 0.170 0.165 0.160

-

-

-

-

'

-

-

-

z

2.90 2.10 1.55 1.05 0.79

r

x

z

2.5 1.80 1.35 0.90 0.67

0.150 0.150 0.145 0.140 0.140

' 2.5 1.80 1.35 0.92 0.68

0.53 0.42 0.3i 0.26 0.21

0.135 0.135 6.135 0.130 0.130

0.55 0.44 0.37 0.30 0.25

" ETHIOPIAN BUILDING CODE STANDARD

!

I,


Table B.37 Multicore armoured P.V.C.-insulated cables (aluminium conductors) Ambient temperature: 30°C Conductor operating temperature:7O"C





1 tWo-core cable; singlephase a.c. or d.c.

1 three- or four-core cable, threephase a.c,

1

2

mm 2

1 two-core cable, single-phase a.c. or d.c.

1 three- or fourcore cable, threephase a.c.

3

4

5

A

A

A

A

16

68

58

71

61

25 35. 50 70 95

89 109 131 165 199

76 94 113 143 174

94 115 139 175 211

80 99 119 151 t86

120 150 185 240 300

-

202 232 265 312 360

-

216 250 287 342 399

:

-

Note: Where the conductor is to be protected by a semi-enclosed fuse, see A.6.2 of the Preface to this

Annex.


\,0.) o"""'"

Table B.36 Voltage drop (per ampere per metre) Conductor operating temperature: 70°C . Conductor cross sectional area

2 cables, single-phase a.c, 2 cables d.c.



Reference Method 12 (Spaced")

Reference Methods 1,11 and 12 (In trefoil touching)



4

5

6

7

mV

mV

mV

mV

\

1

2

mm"

mV

3

rrJV r

x

z

r

x

z

r

x

1

._

r

x

z

r

x

z

50 70 95

1.55 1.05 0.77

1.55 1.05 0.78

0.23 0.22 0.21

1.55 1.10 0.81

1.55 1.05 0.81

0.31 0.30 0.29

1.55 1.10 0.86

1.35 0.92 0.68

0.195 0.190 0.185

1.35 0.93 0.70

1.35 0.93 0.70

0.27 0.26 0.25

1.35 . 1.30 0.96 0.95 0.75 0.73

0.34 0.33 0.32

1.35 1.00 0.80

120 150 185 240 300

0.61 0.49 0.39 0.30 0.24

0.62 0.50 0.41 0.26

0.21 0.66 0.20 0.54 0.195 0.45 0.190 0.37 0.185 0.32

0.65 0.53 0.44 0.34 0.28

0.29 0.28 0.28 0.27 0.26

0.71 0.60 0.52 0.44 0.39

0.54 0.44 0.35 0.28 0.22

0.180 0.175 0.170 0.165 0.160

0.57 0.47 0.39 0.32 0.27

0.57 0.46 0.38 0.30 '0.24

0.25 0.24 0.24 0.23 0.23

0.62 0.52 0.45 0.38 0.34

0.60 0.50 0.42 0.33 0.28

0.32 0.31 0.30 0.29 0.29

0.68 0.58 0.51 0.44 0.40

380 480 600 740 960

0.190 0.150 0.120 0.097 0.075

0.22 0.180 0.15 0.135 0.115

0.185 0.28 0.18 0.25 0.175 0.23 0.170 0.22 0.160 0.200

0.26 0.22 0.195 0.180 0.165

0.25 0.25 0.24 0.23 0.21

0.36 0.33, ,0.31 0.29 0.27

0.185 0.155 0.24 0.155 0.155 0.22 0..1,30 0.150 0.200 0.115 0.145 0.185 0.100 0.140 0.175

0.22 0.195 0.170 0.160 0.150

0.22 0.22 0.21 0.20 0.185

0.32 0.29 0.27 0.26 0.24

0.27 0.26 0.24 0.25 0.21 0.24 0.200 0.22 0.190 0.195

0.38 0.35 0.32 0.30 0.27

1200

0.060

0.110

0.155 0.190

0.160

0.180

0.094

0.145

0.160

0.22

0.185 0.165

0;25

0.3~

0.24

0.140

t Spacings larger than those specified in Method ·12 (see Annex A, Section 8 ) will result in, a larger voltage drop.

I

z

0.170

Table B.35 Single-core armoured P.V.C.-Insulated cable, Non-magnetic armour. (aluminum conductors)

Current-carrying.capacity (Amperes):

Reference Method 1 (clipped direct) Conductor cross sectional area

tv \0

'

Ambient temperature: 30"C

Conductor operating temperature : 70°C Reference Method 11 (on a perforated cable tray)

2 cables singlephase a.c. or d.c. flat and touching

3 or 4 cables three-phase a.c. fiat and touching

2 cables singlephase a.c. or d.c. flat and touching

1

2

3

4

rnm"

A

A

A

50 70 95

143 183 221

133 168 202

152 194 234

120 150 185 240 300

255 294 334 393 452

233 267 303 354 405

270 310 352 413. 474

380 480 600 740 960

518 586 658 728 819

452 501 550 596 651

543 616 692 769 868

479 534 589 642 706

1200

893

S92

952

756

3 or 4 cables three-phase a.c. flat and -tQuching


2 cables single-phase a.c.

2 cables d.c. spaced


Vertical f1atspaced

Horizontal

5'

6

7

8

A·

A

A

141 178 214

168 212 259

246 282 319 374 427

299 340 389 457 520 .




3 cables trefoil

9

10

11

12

A

A

A

A

A

159 200 245

167 214 261

157 202 247

169 213 255

155 196 236

131 168 205

285 323 371 437 498

303 349 400 472 545

288 333 382 452 523

293 335 379 443 505

272 312 354 415 475

238 275 315 372 430

583 655 724 802 866

559 629 696 770 832

638 742 859 986 1171

613 715 828 952 1133

551 604 656 707 770

518 568 618 666 726

497 568 642 715 808

938

902

1360

1317

822

774

880

- Vertical

,

Note: Where the conductor is to be protected by a semi-enclosed fuse. see A,6.2 of the Preface to this Annex.


Table B.34 Voltage drop (per ampere per meter)

Conductor operating temperature: 70°C Conductor crosssectional area

Two-core cable d.c.

Two-core cable singephase a.c,

Three-or four-core cable, three-phase a.c.

1

2

3

4

mV

mV

mV

4.5

4.5

3.9

mm

2

16

r

25 35 50 70 95

r

2.9 2.1 1.55 1.05 0.77

120 150 185 240 300

128

EBCS-10 1995

-

-

2.9 2.1 1.55 1.05 0.77

x

0.175 0.170 0.170 0.165 0.160

-

-

-

z 2.9 2.1 1.55 1.05

0.79

r

x

z

2.5 1.80 1.35 0.90 0.67

0.150 0.150 0.145 0.140 0.140

2.5 1.80 1.35 0.92 0.68

0.53 0.42 0.34 0.26 0.21

0.135 0.135 0.135 0.130 0.130

0.55 0.44 0.37 0.30 0.25

ETHIOPIAN BUILDiNG CODE STANDARD

Table B.33 Multicore P.V.C,-insulated cables, non-armoured (aluminium conductors) Ambient temperature: 30°C Conductor operating temperature: 70°C


Reference Method 4 {enclosed in an insulating waU, etc.) Conductor cross- sectional area

Reference Method 3 {enclosed in conduit on a wall or ceiling, or in trunking) 1 two-core cable, singlephase a.c. or d.c.

·.1 three- or four core cable threephase a.c,

1 two-core cable, singlephase a.c. or d.c,

1 three- or four core cable,three phase a.c.

1

2

3

mm2

A

A

A

A

16

44

41

54

25 35 50 70 95

58 71 86 108 130

53 65 78 98 118

71 86 104 131 157

120 150 185 240 300

-

135 155 176 207 237

-

4

-

1 two-core, cable, singlephase a.c.or d.c.

1 two-core cable, singlephase a.c. or d.c .

1 three- or fourcore cable, three-phase a.c.

7

8

9

A

A

A

A

48

66

59

73

61

62 92 116 139

83 103 125 160 195

73 90 110 140 170

89 111 135 173 210

78 96 117 150 183

160 184 210 248 285

-

197 227 259 305 351

-

212 245 280 330 381

6

n

Note: Where the conductor is to be protected by a semi-enclosed fuse, see A.6.2 of the Preface to this Annex. io-'

tv

.",:I

Reference Method 11 (on a perforated cable tray), or Reference Method 13 (free air)

1 three- or four core cable, three-phase . a.c.

5

-

Reference Method 1 {clipped direct)

-

-

-

------'-----'--------'----------~-----'-_._.-.-.------~-_.

~

~

Table B.32 Voltage drop (per ampere per meter) Conductor Operating TemperaturetXl "C 2 ubIBs - sing/efJIIISB

Conduttu, ctrlss-Sltoolllll

2 ub/es d.t.

'TU

I

R,frJnJnte M,thfJds 3 ,nd 4 (EndtJsed in ttIIIIftitetc., in /If ,n ,

tnIJ

R,frrBnte M,thfJds 3 'lid 4 flllldosed in condtit my in II' on ,

WBIJ

R,fIfIfIf:, MlItltfJds 1, 11 'lid 12 (Tn trefoi tuudIingJ

n,ftJnJnc, Mirthods 1 'nd 11(Flat tDBd*gJ

R,fIfIfIf:, MBthfJd 12 (Flat $psc,,/)

5

,

1

,

,

mY

mY

mY

mY

mY

illY

ow

mY

, 9.77

120 150

0.61

9.49

est

185

0.39 9.30

0.42 0.32

al4

al6 0.22 9.180 9.150

960

al9fJ 9.150 9.120 0.099 0.075

1200

a06/)

600 740

R,fBnJnc, MIItltfJd 12 f$p,ut/)

4

95

48f)

R,ftJnJnc, M,tIIfJds 1 'lid 11 fdippstl dirltt or on lmyS, toudlingJ

3

1.05

380

3 or 4 ulJllJS - tJuee.,/IISB'.c.

2

50 70

240 300

'.e.

1.55

1.60 1.10 0.81

9.64

x 0.30 9.30

I

,

X

I

,

X

I

1.60

1.55

1.55

1.05 0.77

0.190 0.185 0.185

1.55

1.15 9.86

1.05 0.79

1.05 0.77

0.70 0.59 0.50 0.42 0.37

0.61 0.49 0.40 0.30 0.24

0.180 0.175 0.175 0.170 0.170

0.64 0.52 0.43 0.35 9.30

0.49 0.39 030

al7

0.35

0.195

9.32

9.155

9.165 9.165

0.26

0.26 0.27

0.31

0.130 0.105 9.086

9.160 o.f6O 0.1!JD 0.155 0.180

9.125

al5

al8

0.100 0.062

0.25

al4

0.27 0.26

9.074

0.155 0.170

9.068

0.24

0.25

al9 al9 al8 al8 0.27 0.27

al3 all

9.61

0.28 0.27 0.27 0.27 0.26

al6

al4

0.26 0.26

0.195 0.155

0.25

0.25

,

.A.55 1.35 "1.10 0.94 0.82 0.70 0.67 0.55 0.47 0.40 0.35

0.55 0.45 0.36

0.32 0.29

I

,

0.26 0.26 0.25

1.40 0.97 0.74

0.25

X

al8

al4 al4 al4

0.23

0.23

0.61 0.51 0.44 0.37 0.32

0.190 0.23 9.155·'/0.23 0.125 0.22

0.30 0.27 0.26

.

A

I

0.91 0.67

0.165 0.160 0.160

al2 0.69

0.53

9.155

1.35

,

X

I

,

1.35 1.35 9.91

0.24

9.24

1.3$ 1.35 9.94 0.91

0.67

0.23

0.71

0.53 0.42

0.55 0.45 0.37 0.30 0.26

0.67

X

I

0.32 0.31 0.31

1.40 0.96 0.74

0.31 0.30 0.30 0.30 0.30

0.61 0.52 0.46 0.40 0.36

0.29 0.29 0.29 0.29

9.34

0.23 0.23 0.23

0.26 0.21

al2 0.22

0.22 0.195 0.180 0.165 0.155

8.170 0.140 0.110 0.094 0.077

0.22 0.22 0.22 0.21 0.21

0.28

0.23 0.22

0.170 0.135 0.110 0.089 0.071

al9

0.34 0.32 0.31 0.30 0.29

0.0660.135 0.150

0.066

0.21.

0.22

0.059 • 0.28

alB

9.42

0.155 0.34 0.150 0.26 ·0.150 0.21 0.145 0.170 0.140 0.110 0.094 0.077

0.145 0.140 0.140 0.135 0.135

t Spacings larger than those specified in Method 12 (see Annex Annex A of Section 8) will result in larger voltage drop.

9.58 0.53 0.48 0.41 fJ.35 0.31

alB al4

9.42

9.34 0.26 0.21

Table B.3! Single-core P.V.C.-insulated cables, non-armoured, with or without sheath (aluminium conductors) Current-carrying capadty (Amperes): Ambient temperature: 30DC Conductor operating temperature: 70DC Reference Method 4 . (enclosed in conduit in thermally insulating wall etc.) Conductor cross sectional area

Reference Method 3 (enclosed in conduit on a wall or in trunking etc.)


Reference Method 11 (on a perforated cabl tray, horizontal or vertical)



Trefoil

3 or 4 cables, threephase a.c. flat and touchingor trefoil

2 cables, single phase a.c. or d.c. flat and touching

3 or 4 cables,thre e-phase a.c. flat and touching or trefoil

2 cables, singlephase a.c. or d.c. or 3 cables threephase a.c.

2 cables single phase a.c. or d.c. or 3 cables threephase a.c.

3 cables trefoil threephase a.c.


3 or 4 cables threephase a.c.


3 or 4 cables threephase a.c.

2 cables, singlephase a.c. or d.c. flat and touching

1

2

3

4

5

6

7

8

9

10

11

12

rnrn"

A

A

A

A

A

A

A

A

A

A

A

50 70 95

93 118 142

84 107 129

11 B 150 181

104 133 161

134 172 210

123 159 194

144 185 225

132 169 206

163 210 256

148 191 234

128 165 203

120 150 185 240 300

164 189 215 252 289

149 170 194 227 261

210 234 266 312 358

186 204 230 269 306

245 283 324 384 444

226 261 299 354 410

261 301 344 407 469

240 277 317 375 433

298 344 394 466 538

273 317 364 432 501

237 274 316 375 435

-

352 405 462

472 546 626 709 823

543 629 722 820 953

502 582 669 761 886

625 726 837 956 1125

584 680 787 902 1066

507 590 680 776 907

926

1073

999

1293

1229

1026

.

,

-

380 480 600 740 960

-

-

413 477 545

-

-

511 591 679 771 900

1200

-

-

-

-

1022

-

-

Note: Where the conductor is to be protected by a semi-enclosed fuse, see A,6.2 of the Preface to this Annex.

"""" ~



Table B.30 Mineral insulated cables, bare and neither exposed to touch nor in contact with

combustible materials (conte'd)

(copper conductors and sheath)

Voltage drop (per ampere per metre) for single-phase operation:

Sheath operating temperature: 105°C

Three single-core cables


Multicore cables

Rat formation

Touching

Spaced 1 cable diameter apart

2

3

4

5

mV

mV

mV

mV

1.0 1.5

40

27

40

27

40

27

40

27

2.5

16

10

6.8 '4.1 2.6

16

10

6.8 4.1

16

10

6.8 4.1 2.6

16

10

6.8

4.1

2.6

4

6

10

16

x

124

~T

Trefoil touching

2.6 z

x

25

35

50

70

95

1.600.1601.65 1.150.1551.20 0.87 0.150 0.88 0.60 0.145 0.62 0.450.1400,47

. 1.60 1.15 0.88 0.61 0,46

120

150

185

240

0.36 0.135 0.38 0.29 0.135 0.32 0.23 0.130 0.27 0.1800.1300.22

0.37 0.31 0.26 0.22

EBCS-10 1995

---------~----------

0.23 1.65 0.23 1.20 0.22 0.91 0.22 0.65 0.21· 0.50 0.21 0.20 0.20 0.195

x

z

0.42 0.37 0.33 0.29

z

x

1.600.1251.60

1.60 1 .20 0.90 0.63 0,48

0.31 0.30 0.29 0.29 0.28

1.65 1.25

0.95

0.70

0.56

0.39 0.34 0.29 0.26

0.28 0.27 0.26 0.25

0.48

0.43

0.39

0.36

z.



Table B.30 Mineral insulated cables, bare and neither exposed to touch nor in contact with

combustible materials


Voltage drop (per ampere per metre) for single-phase operation Sheath Operating Temperature:

lOS°C Conductor cross-sectional area

Two single-core cables Touching

Multicore cables

1

2

3

A

A

1.0 1.5

47 31

47 31

2.5 4 6 10 16

19 12 7.8 4.7 3.0

19 12 7.8 4.7 3.0

mm

2

.

r

~

i.

x

25 35 50 70 95

1.85 1.35 1.00 0.69 0.51

0.180 0.175 0.170 0.165 0.160

120 150 185 240

0.41 0.33 0.27 0.21

0.160 0.155 0.150 0.150

z .\

r

1.85 1.35 1.00 0.71 0.54

1.85

0.44 0.36 0.31 0.26

-

x

z

0.145

1.85

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

.'


-----.---

.. _------._-~~~~--

EBCS-10 1995

123

-

Table :8.29 Mineral insulated cables bare and neither exposed to touch nor in contact with combustible materials (copper conductors and sheath) (conte'd)

~

Current-carrying capacity (Amperes): Reference Methods 12 and 13 (Free air)


rnrn"

Ambient temperature: 30"C Sheath operating temperature: 105'?C

2 single core cables or 1 two-core cable, singlephase a.c. or d.c.

3 singlecore cables in trefoil or 1 three-core cable, threephase a.c.

10

11

12

13

A

A

A

24 31 41 54

21 26 35 46

20 26 35

1 four-core cable 3 1 four-core cores cable all loaded cores threeloaded phase a.c. .r

1 seven core cable all cores loaded

1 twelve core cable all cores loaded

1 nineteencore cable all cores loaded

14

15

A

A

A

18 22 30

14 18 24

-

3 single-core cables three-phase a.c.

Vertical spaced

Horizontal spaced

Touching

16

17

18

19

A

A

A

A

-

26 33 43 56

29 37 49 64

23 29 39 51

Light duty. 500V

1.0 1.5 2.5 4.0

-

-

-

-

-

-

-

Heavy duty, 750V

-

Note:

1 1.5 2.5 4 6 10 16 25 35 50 70 95 120 150 185 240

n ii) iii)

26 22 22 19 15 13 11 28 32 25 33 28 28 24 19 16.5 14 35 32 40 37 45 38 32 26 22 47 43 54 60 50 49 43 34 61 70 56 63 76 64 54 78 89 71 . 87 104 85 73 105 120 96 137 115 112 97 127 137 157 179 150 146 126 164 178 204 220 184 216 200 248 228 272 266 247 304 279 333 323 370 300 359" 335 400 441 385 385 460 411 441 505 526 441 498 565 469 557 629 530 596 500 584 697 624 704 617 i-or smzre-core caoies, the sheaths 0 the circurt are assumed to be connected tozetl er at both enos. No correction factor for grouping need be applied. Where a conductor operates at a temperature exceeding 7ffC, it shall be ascertained that the equipment connected to the conductor is suitable for the conductor

.

operating temperature.

Table B.29 Mineral insulated cables bare and neither exposed to touch nor in contact with combustible materials (copper conductors and sheath)

Current-carrying capacity (Amperes): Reference Method 1 (Clipped Direct) Conductor crosssectional area

2 single core cables or 1

Ambient temperature: 30"C Sheath operating temperature: 105°C

3 single-core

two-core cable, single phase a.c. or d.c.

cables in trefoil or 1 three-core cable, threephase a.c.

1

2

mm"

3 single-core .cables in flat formation, three-phase a.c.

1 four-core cable 3 cores, loaded threephase a.c.

cable, all . cores loaded

1 seven-core cable all cores loaded

1 twelve-core cable all cores loaded

1 nlneteen-: core cable all cores loaded

3

4

5

6

7

8

9

A

A

A

A

A

A

A

A

22 .38 51

19 24 33 44.

21 27 36 47

18.5 24

16.5 21 28

13 16.5 22

-

-

24 31 42 55 70 127 166 203 251 307 369 424 485 550 643

20 26 35 47 59 107 140 171 212 260 312 359 410 465 544

24 30 41

20 26 35 46 58 103 134

1 four-core

Light duty, 500V

1.0 1.5 2.5 4.0 H~vy

50

70 95 120 150 185 240

,..... N ,.....

33

-

-

-

-

-

duty, 750V

1.0 1.5 2.5 4 6 16 25 35

Note:

28

53

67 119 154 187 230 280 334 383 435 492 572

-

-

-

17.5 -22 30 40 50 90 117

-

14 17.5 24 32

12 15.5 20

-

-

-

-

-

-

-

-

-

10.5 13

-

-

-

-

For smzie-core caoies, the sheaths ot the circuit are assumed to he c.onnp.ctf~d tOlJP.thP.T "t hnth p.nc1" ii) No correction factor for grouping need be applied. iii) Where a conductor operates at a temperature exceeding 7rfJC it shall be ascertained that the equipment connected to the conductor is suitable for the conductor operating temperature. j)


Table B.28 Mineral insulated cables bare and exposed to touch or having an overall covering

of p.v,c

(copper conductors and sheath) (conte'd)

Voltage drop (per ampere per meter) for single-phase operation Sheath operating temperature: 70°C

Conductor crosssectional

area

Three single-core cables Multicore cables

Flat formation

Trefoil, touching Touching_

Spaced 1 cable diameter apart

1

2

3

4

5

mrn"

mV

mV

mV

mV

1.0 1.5

36 24

36 24

36 24

36 24

2.5 4 6 10 16

14 9.1 6.0 3.6 2.3

14 9.1 6.0 3.6 2.3

14 9.1 6.0 3.6 2.3

14 9.1 6.0 3.6 2.3

r 25 35 50 7,'0 95 120 150 185 240

120

1.45 1.05 0.78 0.54 0.40

~

x 0.170 0.165 0.160 0.155 0.150

z 1.45 1.05 0.80 0.56 0.43

0.32 0.150 0.36 0.26 0.145 0.30 0.21 0.140 0.26 0.1650.1400.22

EBCS-10 1995

-------------------

r

x

1.45 1.05 0.79 0.55 0.41

0.25 0.24 0.24 0.23 0.22

z

r

x

z

1.45 1.10 0.83 0.60 0.47

1.45 1.05 0.82 0.58 0.44

0.32 0.31 0.31 0.30 0.29

1.50 1.10 0.87 0.65 0.53

0.33 0.220.40 0.29 0.21 0.36 0.25 0.21 0.32 0.21 0.200.29

0.36 0.32 0.28 0.26

0.28 0.27 0.26 0.25

0.46 0.42 0.39 0.36

r

x

z

1.60 0.125 1.60

-

-

-

-

-

-

-

-

-

-

-

-


, - - - - - - - - - - - - - .- - - - - .- - - - , - - - - - - .- .- - - '

--.-. - - - - . - - ; - - - -- . --- -".


Table B.28 Mineral insulated cables bare and exposed to touch or having an overall covering of p.v,c


Voltage drop (per ampere per meter) for single-phase operation sheath operating temperature: 70°C·

.


Two single-core cables, Touching

Multicore cables

1

2

3

mrn"

mV

mV

1 1.5

42 28

42 28

2.5 4 6 10 16

17 10 7 4.2 2.6

17 10 7 4.2 2.6

x

r

x

25 35 50 70 95

1.65 1.20 0.89 0.62 0.46

0.200 0.195 0.185 0.180 0.175

1.65 1.20 0.91 0.64 0.49

1.65

120 150 186 240

0.37 0.30 0.25 0.190

0.170 0.170 0.165 0.160

0.41 0.34 0.29 0.25

-

ETHIOPIAN BUILDING CODE SfANDARD

z

r

0.145

-

-

-

-

-

EBCS-10 1995

-----~._----~-.--.-----.-----

z 1.65

-

-

-

-

-119


(3) A copper earthing conductor of IO.Omm 2 shall be in conduit, electrical metallic tubing or cable armour. (4) Metal enclosures for earthing conductors shall be continuous from the point of attachment to cabinets or equipment to the earthing electrode and shall be securely fastened to the earthing clamp or fitting. (S) Where an earthing conductor is run in the same racewaywith other conductors ofthe system to which it is connected, it shall be insulated, except that where the length of the raceway does not exceed IS.Om between pull points and does not contain more than the equivalent of two quarter bends between pull points, an uninsulatedearthing conductor may be used. ( 6) Notwithstanding the requirements of (2) above, earthing conductor of Ie.Omnr' or larger may be embedded in concrete provided that the points of emergency are so located or guarded as not to constitute exposure to mechanical injury..

7.9.3

Installation of Bonding Conductors for Equipment

(l) The bonding conductor for equipment shall be permitted to be spliced or tapped; but such splices or taps shall be made only within boxes except that, in the case of open wiring, they shall be permitted to be -made externally from boxes and shall be covered with insulation.

(2) .Where more than one bonding conductor enters a box, all such conductors shall be in good . electrical contact with each other by securing all bonding conductors under bonding screws, or by connecting them. together with an acceptable solderless connector and connecting one conductor only to the box by a bonding screw or a bonding device, and the arrangement shall be such that the disconnection or removal of a receptacle, fixture, or other device fed from the box, will not interfere with or interrupt the bonding continuity. (3) Where a bonding conductor is run in the same raceway with other conductors of the system to which it is connected, it shall be insulated, except that where the length of the raceway does not exceed 15.0m and does not contain more than the equivalent of two quarter bends, an uninsulated bonding conductor shall be permitted to be used. (4) Where a rigid metal conduit or steel pipe is used as a bonding conductor, the installation shall comply with Section 8 of this Code.

. 173

EBCS·10 1995



(5) A copper bonding conductor shall: a) if Ie.Omrrr' or larger and attached securely to the surface on which it is carried, be protected where exposed to mechanical injury; and b) if smaller than l e.Omrrr' or if the installation does not come within the provision in (a) above, be installed and protected in the same manner as the circuit conductor for a given installation. (6) An aluminium bonding conductor shall: a) if 25.0mm2 or larger and attached securely to the surface on which it is carried, be protected where exposed to mechanical injury; or b) if smaller than 25.0mm 2 or if the installation does not come within the provisions in (a) above, be installed and protected in the same manner as the circuit conductor for a given installation. (7) Where a separate bonding conductor supplements the bonding afforded by a ferrous metal raceway, it shall be installed in the same raceway as the circuit conductor.

7.9.4

Earthing Conductor Size for D.C. Circuits

(1) The ampacity of the earthing conductor for a direct-current supply system or generator shall be not less than that of the largest conductor supplied by the system, except where the earthing circuit conductor is a neutral derived from a balancer winding or a balancer set, the size or the earthing conductor shall be not less than that of the neutral conductor.

(2) The system earthing conductor shall be copper and in no case smaller than 10.0m~.

7.9.5

Eathing Conductor Size for A.C. System

(1) The size of the earthing conductor shall not be less than those given in Table 7.1

7.9.6

Bonding Conductor Size

(1) The size of a bonding conductor shall be not less than that given in Table 7.1; but in no case does it need to be larger than the largest unearthed conductor in the circuit.">


EBCS-101995

174


7.10

EARTHING AND BONDING CONDUCTOR CONNECTIONS

7.10.1 Bonding Conductor Connection to Raceways (1) The point of connection of the boriding conductor to interior metal raceways, cable armour and the like shall be as near as practicable -to the source of supply and shall be chosen so that no raceway or cable armour is bonded through a run of smaller size that is called for in Clause 7.9.6.

7.10.2 Earthing Conductor Connection to Water Pipe Electrodes (1) Where the earth electrode is a metal water-piping system to which a common earthing conductor or the earthing conductor of a system is attached, the point of attachment shall be a) on the street side of the water meter; or b) on a cold-water pipe of adequate ampacity and as near as practicable to the point of entrance of the water service in the building. (2) Where practicable, the point of attachment shall be accessible. (3) The metal cold water system shall be made electrically continuous from the point of attachment of the earthing conductor to the water service entrance by bonding together all parts thereof if these parts contain insulating section or may become disconnected at meters, valves and unions. (4) Equipment may be earthed to a cold-water pipe which is near the equipment.

7.10.3 Eathlng Conductor Connections to Other-Than-Water-Pipe Electrodes I

(l) Where a! metal water-piping system is not available, the earthing conductor shall be attached to other electrodes at a point which will assure a permanent earth.

(2) Where practicable, the point of attachment in (l) above shall be accessible.

175

EBCS-10 1995



7.10.4 Bonding Conductor Connection to Circuits and Equipment (1) The bonding conductor or bonding jumper shall be attached to circuits, conduits cabinets equipment and the like, which are to be bonded, by means of lugs, pressure wire connector clamps, or other acceptable means. (2) Connections which depend on soldering shall not be used. (3) The bonding conductor shall be secured to every metal box by means of a bonding screw which shall be used for no other purpose. (4) The bonding conductor shall be brought into every nonmetallic outlet box in such a manner than it can be connected to any fitting or device which may require bonding to earth. (5) Equipment shall be so installed that, if the connections between the branch circuit and the . internal conductors pass through an access cover, the bonding connection shall remain continuous when the cover is removed. (6) A bonding jumper shall be installed to connect the bonding conductor to the earthing terminal of a socket outlet and in such a manner that disconnection or removal of the socket outlet will not interfere with or interrupt earthing continuity. (7) In the case of metal-enclosed systems where the earthing path is provided by the metal enclosure, a bonding jumper shall be installed to bond the earthing terminal of the socket outlet to the enclosure. (8) Notwithstanding the Provisions of (6) and (7) above, the bonding jumper, in the case of socket outlets having earthing terminals isolated from the mounting strap required for special equipment, may be extended directly back to the distribution panel.

7.10.5 Earthing Conductor Connection to Electrodes (1) The earthing conductor shall be attached to the earthing electrode by means of: a) b) c) d)

a bolted clamp,

a pipe fitting plug or other device screwed into the pipe or into the fitting,

copper welding by the thermit process brazing or silver solder, or

ether equally substantial means.


----_._-----_.~--

EBCS-10 1995

176


(2) Where a bolted clamp is used for a wet location or for direct earth burial, the clamp shall be of copper, bronze or brass, and the bolts shall be of a similar material or of stainless steel. (3) The earthing conductor shall be attached to the earthing fitting as required by Clause 7.10.4(1). (4) Connections which depend on solder shall not be used except for connections utilizing silver solder. (5) Not more than one conductor shall be connected to the earthing electrode by a single clamp or fitting unless the clamp or fitting is specifically designed for multiple conductor connection.

177

EBCS-10 1995

ETHIOPIAN BUILD~G CODE STANDARD

~-~---

~

--

--,---

-

-

---------~

..__

._---------~----~-----.--------,

..._-

SECTION

7

EARTHING, BONDING, AND LIGHTNING PROTECTION

PART II - LIGHTNING PROTECTION

7.11 . SCOPE (1) This Part of the Code covers the installation of lightning protection requirements for all types of structures with the exception of those structures used for manufacturing explosives. (2) Electric generation, transmission and distribution systems, overhead telephone lines, and radar stations are not covered by this Code.

7.12


(1) The following references contain provisions which, through reference in thistext, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings.

(a) BS 6651:1986

. (b) NSIINFPA78:1986 (c) UL 96A:1983

British Standard Code of Practice for Protection of Structures against Lightning, 1990 An American National Standard), Lightning Protection Code. Underwriters Laboratories Standard for Installation Requirements for Lighting Protection systems, Ninth Edition.


EBCS-10 1995

178


7.13

DEFINITIONS

.

(1) For the purpose of this Section, in addition to the terms defmed in Section 1, the following definitions shall apply:

lightning flash

an electrical discharge between cloud and earth, of atmospheric origin, comprising one or more impulse of many kiloamps.

lightning strike

a lightning flash attaching to a structure.

lightning stroke

one of the single distinguishable current impulses of a lightning flash.

lightning protection system a complete system of air termination, conductors, earth termination; interconnection conductors, and other connectors and fittings required to protect a structure from the effect of.lightning, air termination

that component of a lightning protection system that is intended to intercept lightning flushes.

down conductor

a conductor intended to be used to carry lightning currents between air termination and earth termination.

bond

a conductor intended to provide electrical connection between the lightning protection system and other metal-works and between various portions of the latter.

joint

a mechanical and/or electrical junction between two or more portions of a lightning protection system.

test joint

a joint designed and situated so as to enable resistance or continuity measurement to be made.

earth termination

that part of a lightning protection system which is intended to discharge lightning currents into the general mass of earth.

179

EBCS-10 1995



ring (loop) earth electrode an earth electrode forming a closed loop round the structure below or on the surface of the earth, or within or under the foundations. It may be lJsed for interconnecting other earth electrodes. side flash

an electrical spark, caused by differences of potential, occurring between conductive metal bodies and component of lightning protection system or earth.

zone ofprotection

that space adjacent to a protection system which is substantially immune to direct lightning flashes (see Figure 7.2).

7.14

MATERIALS

7.14.1 General (1) A lightning protection system t shall be made of materials that are resistant to corrosion or shall be acceptably protected against corrosion. (2) No combination of materials that forms an electrolytic-couple of such nature that, in the presence of moisture, corrosion is accelerated shall be used. Note:

One or more of the following materials are acceptable: i) ii) iii) IV)

Copper of the grade ordinarily required for commercial electrical work, generally designated as being of 98% conductivity when annealed. A copper alloy as resistant to corrosion as copper under similar condition. Aluminium conductors of electrical grade aluminium. Galvanized steel with cross-sectional area equivalent to that of copper.

7.14.2 Galvanic Compatibility (1) Metals shall be used in combination that are galvanically compatible.

t The principal parts of a lightning protection system are air termination, down conductors, joints and bonds, test joints, earth termination, and earth electrode.

ETHIOPIAN BUILDING CODE STANDARD -----------------

EBCS-10 1995

180

I

I

)

SECTION?: EARTHING, BONDING AND LIGHTENING PROTECTION

7.14.3 Corrosion Protection (1) Components shall be protected against corrosion; any part of a copper system that is exposed to direct action or chimney gases or other similar corrosive gases shall be protected by a continuous hot-dipped coating of lead.

(2) All components located within 610.0tnm of the chimney top shall be so protected. (3) Aluminium components are not required to have a coating of lead.

7.14.4 Mechanical Protection (1) Any part of a lightning protection system that is subject to mechanical damage or displacement shall be protected with a protective moulding or tubing.

(2) Metal pipe or tubing shall be bonded to the conduit at both ends of the tubing. (3) Conductors shall be securely attached to objects upon which they are placed (see Figure 7.1 and Table 7.5).

7.14.5 Use of Aluminium (1) Aluminium systems shall be installed in accordance with other applicable clauses and subject to the following conditions:

a) Aluminium lightnin~-protection components shall not be installed directly on copper roofing materials or other copper surfaces where exposed to the run off from copper surfaces. b) (i) Aluminium components shall not be used where they corne into direct contract with

earth. (ii) Fittings used for the connection of aluminium earthing equipment shall be of the bimetallic type; such bimetallic connectors shall be installed not less than 460.0mm

above ground level.

181

EBCS-10 1995


-----.- ... _----._---~~~._--_._._---

ELECTRICAL INSTALLATION OF BUlLDINGS

c) Aluminium conductors and components shall not be i)

embedded in concrete or masonry;

ii) in direct contact with a surface coated with an alkaline base paint; or

iii) installed in a location subject to excessive moisture.

Note:

Copper lightning~pwtection components shall'not be installed directly on aluminium roofing, siding or other aluminium surfaces.


.Table 7.3 Minimum dimensions of component parts

Component

Air terminations: aluminium, copper

and galvanized steel

strip.

aluminium, aluminium alloy, copper, phosphor, bronze and galvanized steel rods Suspended conductors: stranded aluminium

stranded copper

stranded aluminium (steel reinforced) stranded galvanized steel Down conductors: aluminium, copper and galvanized

steel strip

aluminium, aluminium alloy, copper and

galVanized steel rods

Earth terminations: austenitic iron copper and galvanized steel strip copper and galVanized steel reids hard drawn copper rods for direct driving

into soft ground hard drawn or annealed copper rods or solid wires for

indirect driving or laying in ground rods for hard ground

copper-clad or galvanized steel rods (flee notes to table) for

harder ground

Dlmenslo ns

Area

mm

mm

20 x 2.5

50.0

8.0 dia.

7{3.0

Area

mm

mtn 2

Fixed connecltions(bonds) In

aluminium, aluminium alloy, copper

and galvanized ste6l:

extemal strip external rods internal strip intemal rods

20 x 2.5 8.0 diil. 20 x 1.5 6:5 dia.

50.0 50.0 30.0

Flexible or lam[nated connections

(bonds):

external, aluminium external, annealed copper intemal, aluminium intemal, annealed copper

20 x 2.5 20 x 2.5 20x 1.5 20x 1.5

Component 2

50.0

713.0

50.0 50.0 50.0

7/3.0

50.0

19/1.8

Dknenslo ns

20x 25

50.0

8.0 dia.

50.0

Note

~

14.Odia.

153.0

20 x 2.5

50.0

8.0 dia.

50.0

8.0 dia.

50,0

8.0 dia.

50.0

12.Odia.

113.0

Iv)

14.OdIa.

153.0

v)

ii)

i1~

vi)

183

EBCS-10 1995

3~.{)

50.0

15M 30.0 30.0

For copper"Clad steel rods, the core should be of loW catbon steel with a tensile strength of approximately 800.0Nlmm2 and of a qUality not less than grade 43.OA of as 4380. The cladding should bEt of 99.9% pure electrolytic cooper molecUlarly bonded to the steel core. Theradilll thickness of the copper should be not less than O.25mm.

Couplings tOr copper"Clad steel rods should be made from copper-silicon alloy, grade C9101 or BS 2874, or aluminium bronze alloy, grade CA102 of BS 2871.

The use of intemal phosphor bronze dowels may give a lower resistance than the extemal couplings of diameter greater than the rod.

For galvanized steel rods, steel of grade 43.OA specified in BS 4380 should be used, the threads being cut before hot~ip galvanizing to BS 729.

Stranded conductors are not normally used for down conductors or earths. Greater dimensions are reqUired for the following:. • structureS exceeding 2O.0m In height. • Special classes of structure. • Mechanical or corrosive rellllOl1s.

ETHIOPIAN aUILDING CODE STANDARD


Table 7.4 Minimum thicknesses of sheet metal used for roofing and forming Part of the air termination net work

Minimum thickness [mm]

Material

Galvanized steel Stainless steel Copper

Material

Minimum thickness [mm]

Aluminium nd Zinc Lead

0.5 ·0.4 0.3

0.7 2.0

Note: The figures in this table are based on contemporary building practice and will be satisfactory where the

roofs form part of the lightning protection system. However, damage by way of puncturing may occur with a direct arc-connected strike.

Table 7.5 Recommended fixing centres for conductors

Arrangemen~

c~'

Horizontal conductors on horizontal surfaces Horizontal conductors on vertical surfaces \ Vertical conductors Vertical conductors over 20.0m Vertical conductors over 25.0m

Fixing centres [mm]

1000 500 1000 750 500

Note: This table does not apply to built-in type fixings which may require special consideration.

7.15

FORM AND SIZE

7.15.1 Air Termination (1) Vertical air terminations shall be made of solid or tubular rods.

(2) Horizontal air terminations shall be made of solid conductor, strips or cables.

. ETHIOPIAN BUILDING CODE STANDARD

EBCS-10 1995

184


7.15.2 Conductors (1) Conductors shall be in the form of multiple strand cables, single wires, rods, or flat strips. . 7.15.3 Earth Termination (1) Earth termination shall be made of rods plates or stranded cables. ·7.15.4 Minimum Dimension (1) The component part of lightning protection system shall have dimensions not less than those given in Tables 7.3 and 7.4.

7.16

AIR TERMINATION

7.16.1 General (1) Air termination networks shall be provided for all parts of a structure that are likely to be damaged by direct lightning Flashes. Note:

Air networks may consist of vertical or horizontal conductors or combination or both. Various forms of air terminations are shown in Figures 7.7 through 7JS.

7.16.2 Support (1) Vertical air terminals shall be secured against overturning either by attachment to the object to be protected or by means of braces which shall be permanently and rigidly attached to the building.

7.16.3 Metallic Projections (1) All metallic projections on or above the main surface of the roof which are connected, intentionally or fortuitously, to the general mass of the earth shall be bonded to and form part of the air termination network (see Figures 7.4 and 7.5).

185

- - - - - - -...• - - - -

EBCS-10 1995

------

ETHIOPIAN BUILplNG CODE STANDARD

-------_._~----------.-_._-_._---


7.16.4 Metallic Materials (1) Metallic coping, roof coverings, hand rails, window washing equipment and metallic screens around play areas shall be considered for inclusion as part of the air termination network (see Figures 7.4, 7.5 and 7.6).

7.16.5 Structure within Zone of Protection (1) Air termination shall not be required fot those parts of a structure located within a zone of protection. (2) If portions of a structure vary considerably in height, any necessary air termination or air termination network for the lower portions shall be joined to the down conductors of the taller portions in addition 1;f;) being joined to their own down conductor.

7.16.6 Air Termination on Roof (1) One roof air termination 'shall be placed or. ridges of a roof and around the perimeter of the roof.

7.16.7 Air Termination on Reinforced Concrete Structure (1) If the reinforcing bars are used as down conductors, the air termination shall be connected to the reinforced bars in the number of positions required for down conductors.

7.17

DOWNCONDUCTOR

7.17.1 General (1) A down conductor shall provide a low impedance path from air termination to earth termination so that the lightning current can be safely conducted to earth. Note:

In addition to the various types of down conductors; i.e., strips, rods, reinforcing bars and structural steel stanchions, etc any good conductor which may form part of the building structure can be included provided that it is appropriately jointed to the air and earth terminations.


EBCS-10 1995

186


7.17.2 Routing Down conductors shall follow the most direct path possible between air and earth termination networks. The conductors shall be arranged as evenly as practicable around the outside walls of.the structure (see Figure 7.17).

7.17.3 Recommended Number (1) At least two down conductors shall be provided on any kind of structure.

7.17.4 Mechanical Protection (1) Each down conductor located in a runway, school play ground, or other similarlocation shall be guarded against mechanical damage or displacement.

(2) The down conductor shall be protected for a minimum distance of 1.8m above grade level.

7.17.5 Corrosive Soil (1) A down conductor entering corrosive soil shall be protected against corrosion for not less . than 915.0mm above grade level and for entire length below grade level.

7.17.6 External Routes Not Available (1) When the provision of suitable routes for down conductors is impossible, ego buildings of cantilever construction from first floor upwards (see Figure 7.18), down conductors shall not follow the outside contours of the buildings. (2) In cases such as (1) above, down conductors may be housed in an air space provided by non-metallic, non-combustible internal duct and taken straight down to ground. Note:

Any suitable covered recess not smaller than 76.0mm x 13.0mm or any suitable service duct running the full height of the building may be used for this purpose provided it does not contain an unarmored or non-metal sheathed service cable.

(3) In case where an unrestricted duct is used, seals at each floor level may be required for fire protection. (4) Where possible, access to the interior of the duct shall be available.

187

EBCS-10 1995


----~-----~----~


7.17.7 Lift Shafts (l) Lift shafts shall not be used for fixing down conductor.

7.17.8 Re-entrant Loops (1) When a large re-entrant loops [see Figure 7.18 (b)] cannot be avoided, the conductor shall pass through holes as shown in Figure 7.18 (c).

7.17.9 Sharp Bends (1) No bend of a conductor shall form an included angle of le~s than 90° or have a radius of bend less tharr203.0mm (see Figure 7.16).

7.17.10

Bonding to Prevent Side Flashing

(1) Any metal in or forming part of the structure or any building services having metallic parts by design or fortuitously and in contact with general mass of the earth shall be either isolated from or bonded to the down conductor. " Note:

7.17.11

Unless extra bonding is required,items already in metallic contact with the lightning protection system, directly or indirectly, through permanent and reliable metal-to-metal joints do not require additional bonding conductors ..

Bonds

7.17.11.1 General (l) Since bonds have to join a variety of metallic parts of different shapes and composition, careful attention shall be given to .the metals involved; i.e, that of the bond and of the items being bonded.

7.17.11.2 Mechanical and electrical requirements (1) A bond shall be mechanically and electrically effective and protected from corrosion and erosion by the operating environment.


EBCS-10 1995

188


7~17.11.3

External metal

(l) External metal on or forming part of a structure shall be bonded to the lightning protection system with a main-sized conductor.

7.17.11.4 Internal metal (1) Internal metal bonds may be reduced in size; but shall not be smaller than 35.0mm2 copper or its equivalent.

7.17.11.5 Provision for bonding offuture equipment (l) In all buildings, at each floor level, provision shall be made for bonding future machinery or equipment to the lightning protection system; i.e, by connection to metallic gas, water, drainage or similar services.

7.17.11.6 Joints (l) Joints shall: a) b) c) d)

be as few as possible;

be mechanically and electrically effective;.

be protected against corrosion or erosion from the elements of the environment; and

present an adequate contact area.

Note:

Contact surface shall first be cleaned and then inhibited from oxidation with a suitable non-corrosive compound.

(2) With overlap joints, the overlap shall not be less than 20.0mm for all types of conductors.

7.17.12

Test Points

(1) Earth down conductor shall be provided with a test joint in such a position that, whilst not inviting unauthorized interference, jt is convenient for test (see Figure 7.25 for typical test joints), Note:

189

Plates indicating the position, number and type of earth electrodes should be fitted above each test point

EBCS-10 1995


:eLECTRICAL INSTALLATION OF BUILDINGS

7.18

EARm TERMINATION

7.18.1 Termination (I) Each down conductor shall terminate at -an earth electrode.

7.18.2 -Resistance to Earth (1) Each earth electrode shall have a resistance (in ohm) not exceeding the product given by 10 times the nuinber of earth electrodes to be provided.

(2) The whole of the earth termination network shall have a combined resistance to earth 'not exceeding 10 ohm without taking account of any bonding to other services.

7.18.3 Earth Electrodes

7.18.3.1 General (I) Earth electrodes shall consist of metal rods, tubes or strips' or' a combination of these or

natural earths such as piles and foundations (see Figure 7.20). 7.18~3.2

Earth rod connection

(I) Earth rod connections shall be made by welding, bracing or clamping. (2) Clamps shall be secured with at least two bolts or screw caps and shall make contact with

the earth rod for at least 380.0mm.

7.18.4 Connection Point (I) The point of connection of the earth termination network shall be removable and easily

accessible from above-earth to facilitate inspection, testing and maintenance of the lightning

protection system.

(2).If below ground, the point of connection shall preferably be housed in a purpose-built -inspection pit or chamber.


--------------------------

EBCS-10 1995

190

c---------------

SECTION 7: EARTHING J BONDING AND LIGHTENING PROTECTION

7.18A.l

Deep moist clay soil

(1) Earthing rod shall extend vertically not less than 3.Om into the earth.

(2) The ground shall be compacted and made tight against the full length of the conductor or earth rod (see Figure 7.19).

7.18.4.2 Sandy or gravely soil (1) In sand or gravel, two or more earth rods at not less than 3.Om spacings shall be driven vertically to a minimum depth of 3.0m below grade (see Figure 7.21).

7.18.4.3 Shallow top soil (I) If bedrock is near the surface, the conductor shall be laid in trenches extending away from

the building at each down conductor. (2} Trenches in O} above shall at least be:

a} 3.1m long and 610.0mm deep in clay soil;

o} 13m long,and 616.0mm deep in sandy or gravely soil,

(3) If these.. methods should prove impracticable, the lightning protection cable may be laid directly on the bedrock with. a minimum distance of 610.0mm from the foundation or exterior footing and terminate by attachment to' a buried copper earth plate at least O.8mm thick and heving a minimum surface area of O..18mz . 7a8~4.4

Soilless: than· fl3m deep

(1). If soil is less than 03m in depth, down conductors shall be connected to a loop conductor in8tal1ed in. a trench or in rock crevices around the structure. J

.

.

(2) til The loop conductor shall not be less than the equivalent of a main size lightning conductor.

ETHl'OPfAN BUU_DING CODE STANDARD

,ELECTRICAL INSTALLATION OF BUILDlNGS (ii)

-,

Optional earth plates may be attached to the loop conductor to enhance its earth contact, where the measured earthing resistance is found to be high to provide effective earthing (see Figure 7.22).

7.18.4.5 Barth electrode seal for use within a tanked structure

(1 ) When earth terminations in built-up areas pass through a tanked structure, a seal similar to that shown in Figure 7.23 shall be used. 7.18.4.6 Corrosion

(1) Because of the harmful corrosion which is likely to result, coke breeze shall not be allowed to be in contact with'copper electrodes and salting of the ground in the vicinity of any earth electrode is not recommended. 7.19' COMMON EARTHING 7.19.1 CommoQ Earth Potential

(1) All earthing mediums in or on a structure shall be interconnected to provide a common earth potential. (2) The Provision in 0) above shall include lightning protection, electric service, telephone and antenna.system earths as, well as underground metallic piping systemsj main size lightning conductors shall be used for interconnecting these earthing systems to the lightning protection system. 7.19.2 ,Common Earth Bonding (1) If electric, telephone, or other systems are earthed to a common earthing terminal (see

Figure 7.24), one connection from the lightning protection system to the terminal is required. (2) If the service systems are earthed to a metallic water pipe, only one connection to the lightning systemis required provided that the water pipe is electrically continuous between all systems.

,

/'

,

ETHIOPIAN BUILDING CODE STANDARD \

EBCS-10 1995

192

SEC"nON 7: EARTHING, BONDING AND LIGHTENING PROTECTION

(3) If the water pipe in (2) above is not continuous, the non-conductive sections shall be bridged with main size conductors, or the connection shall be made at a point where electrical continuity is assured.

7.20

USE OF REINFORCING BARSFOR EARTHING IN CONCRETE STRUCTURES

7.20.1 General (1) Detail on how to use concrete reinforcing bars shall be worked out at the design stage before building construction begins (see Clause B.6, Annex B).

7.10.2 Electrical C::ontinuity (1) Electrical continuity of the reinforcement shall be ensured. (2) The following precautions are, however, recommended: a) Good contact between reinforcing bars should be ensured; i.e, by fixing bars with tying wires. b) Ties shall be provided for both vertical to vertical and horizontal to vertical bars.

·7.20.3 Prestressed Concrete Members (1) Lightning protection conductors shall not be connected to prestressed concrete columns, beams or braces where the wires or strands. are. not linked and, therefore, not electrically continuous.

7.20.4 Precast Concrete Members (1) In the case of precast reinforced concrete columns, beams or braces, the reinforcement may be used as a conductor if the individual elements of reinforcement are bonded together and i electrical continuity is ensured. "

193

EBCS-10 1995



7.21

STRUCTURAL STEEL FRAMING FOR LIGHTNING PROTECTION

7.21.1 General (1) The structural steel framework of abuilding may be used as the main conductor of a lightning protection system if it is either electrically continuous or made so.

1.21.2 Air Termination (1) Air.termination shall be bonded directly to the steel framework or by conductors leading through the ridges, roof, or coping walls, or connected together with a conductor on the exterior of the building that is bonded to the steel framework. (2) If such a conductor in (l) above is employed, it shall be bonded to the framework at intervals not more than 3.0m.

7.21.3 Connection (1) Connection shall be made on cleaned areas of the steel work by use of bonding plates with pressure cable connectors having a surface contact area of not less than 5200.0mm?; bolted, welded, or brazed securely to the steel so as to maintain electrical continuity.

7.21.4 Earthing (1) Earthing connections shall be made at approximately every other steel column around the perimeter and shall not average more than 18.0m apart. (2) The earthing conductor shall be connected to steel columns using bonding plates (see 7.21.3). (3) The bonding plate shall be bolted or welded securely to a cleaned area of.the column at the lowest available point (see Figure 7.26).

7.21.5 Interconnection (1) Metal bodies that are required to be bonded need not be-separately bonded if they electrically continuous with the lightning protection system/through the steel framework.:

ETHIOPIAN BUILDING CODe STANDARD

EBCS-10 1995

ar~

194


lal

Ibl

fcJ

1 Strip

.Iel

Idl

Iql

Note:

i)

Lightning conductor fixings shouldbepurpose-made for each size of strip; dimension a ,in Figure (e) should be equal to the thickness of the strip and should be equal to the width ,plus '1)mm .R for expansion. Conductors of circularsection should be similarly treated.

ii) All fixings should be securely attached to the structure; mortar joints should notbeused.

.F igure7.1 Typical design for lightning conductor fixings

195

-

-----~.-

EBCS-10 1995

----


--~------------.-.-_.-.

------_._-


He

GL

GL /

Pion view 01 zono 01 protection It ground Ilvll

<,

,/'

/

I

-,

/

ve

\

--Zp

<,

,I ./

/1' One verticil conductor

! (

....

/

~-"

-,

Zp - \

veo

veo

-,

\

0

\

Zp

-,

<,

--_/

I

I

/

J

, J

rlBn vlo.. \ 01 zono 01 prOlltCtlon It ground _ lew'

>

<

{

n

VC

ZP "

-........:.

-

\

e

vC

\ \

I

Pion vlo.. 01 zonl 01 protlctlon It ground Ilvll

(bl HorlzontBI IJr tlrmlnBtlon

....'- --....-.

Zp

<,

He

I

\ l-

0

---

I

\

{

\

/'

.....-...

--

/ Zp /

Icl Four vlrtlcl' conducto.. 'howlng protlctlvo Inglll Ind l ..ocl"ld zonn 01 protletlon . -

/'

Figure 7.2 Protective angles and zones of protection for various forms of air termination-


EBCS-10 1995

.

196

------------


."-

f = - - ..

... .' "

II_,....

·~

Figure 7.3 Typical forms of vertical air termit;1ations

197

EBCS-10 1995

.ETHIOPIAN BUILDINQCODE S!ANDARD

ELECTRICAL INSTALLATiON OF BUILDINGS

.~

KIY .

I Air I"mlnl'

€==::=

2 Rod "oldll'u,

~

Q

3 Rod coupling

4 D_n conductor

a Horizon"l conduclor

.

-$

6 TOInoln, 7 Earl" IllCIrodo

~

8 El
I~J

9 Rod hOUilng 1.1 CIlI.......... lesllhan 1.5 m dlama,.. allap. and 20 m "IP

10 Cond"clor clip 1t COrolll!band

12 Sond 10 _I Iron cap II .

•".rn.lI.. '0 COton.' band lUI.

13 Juncllonclamp'

Nole This figure does not apply to reinforced concrete chimneys where the reinforcing bars can be used as do~

conductors

Figure 7A Examples of lightning proteetiollsystems for briek chimneys

ETHIOPIAN BUILD'tNG CODE STANDARD

EBCS- to 1995

19. i

i i I


, Bimetallic joint

Galvanized steal roof

. Reinforced concrete structure with parapet, stone coping and . non-eonducting roof

Bonds to steelwork

Reinforced concrete structure, PVC coping with conducting roof

Bond to metal IUlpended ceiling II

I"I

4 One reinforcing bar Ihown for clarltv

3

'I

"

4~'''~~1J

" 'I 4 ".....

--1""....

2

Key

Detail Ihowlng item 4

I 2 3 4

Handrail bond Reinforcing bond Coping bond

Non-ferrous bonding point (built-in)

Figure 7.5 Examples of air terminations and down conductors using handrails, metal copings and reinforcing bars.

199

EBCS-10 1995



.....- Bolted joint

connection 2.. M8 Conductor strip

BeQm-_-+__

Note:

Minimum dimensions when a metallic roof covering is used as part of the air termination network are as follows: galvanized steel copper aluminium

IO.5mm O.3mm O.7mm

zinc· lead

O.7mm 2.0mm

Figure 7.6 Air termination for flat roof showing connection to standing seamjoint when a metallic roof is used as part of the air termination network


EBCS-10 1995

200


(II Elevation Ihowlng protective engle

,,;-------- /

I I

·1

HC

1

HC

~

\

I I

I

1 I I

I

'Oml max,)

I

HC

·1

I

I

./

\

-, <,

-

HC

I.

20m

_ _ _ZP_

fbI Plln Ihowlng zone of prot'!Ctlon It ground leVlI

---

/

/

I I /

HC .......

<,

<, .\

,,'

".

"

<, _

"" "" ""

J

",

""

-Zp--, ..

Ic) Generll Irrlngement

F.'igure 7.7 Air terminations for a flat roof

201

EBCS-10 1995



r

S

1

~H

Note:

i)

If S> 10 I 2H, additional longitudinal conductors are required so that the distance between conductors does not exceed IO:Om. ii) If the length of the, roof exceeds 20.0~, additional transverse conductors are required. iii) Down conductors are omitted for clarity.

Figure 7.8 Air terminations for large areas of roof various profiles


EBCS-1 0

19~5

202


Test

Test

joint~

joint ....... -"-

DC

DC

I

I

I

f

I I

I

I I I

I

,

,

I

:-r-

I

DC

1

20 m

"'16:'=m-:::'_..-1.1 DC

111

L....:

DtoJ· I..

10 m • IDC

M,tolU'

D C

Test

joint

DC

I

I I I I I

I I I I I

16 m

I I

,ut"'h"~I_..

IDC

,----,=,--_.... 16 m

121

131

Note: The protective angle provided by the ridge conductor in each case is as follows: (i) protective angle up to 45° : ridge conductor is sufficient with connection to metallic gutters; number of down conductors=72/20=3.6 (say4). (ii) protective angle over 45~: air termination mesh (maximum 1O.0m x (10+2H)); ridge and eaves conductors provide approximate roof mesh 6.0m x IQ.Om; number of down condl.lctors=40/20=2. (iii) situation as for (ii) but metallic gutters used in lieu of eaves conductor; number of down conductors =64/20=3.2 (say4).

(a) Air terminations 'and. down conductors Vertical air terminati:m . Conductor for strip rod or. metallic gulter

Ri'dge ccmductor fixed belov tile ",leyel (see detail J

Det.1I

Key:Conceald conductors-s- O.3m high bar vertical rods.

(b) Air· terminations below roof covering

Figure 7.9 Air terminations and concealed conductors for buildings less 20.0m high witb stopping roofs

203

EBCS-10 1995

ETHIOPIAN BUILDING QODE STANDARD

------.------

.•...... _----

- - - -


......

, '...",.

,/ ,/

,/

View from B

-Join down conductorland horizontal conductorl on lower parapet. Section A·A

DC

r

...

A

HC

DC·

0 tB

aDC HC

_.

f

12

A

DC

12m

Note:

Perimeter· 24 + 24 + 12 + 12 • 72 m • Number of down conduclon reqt,llred 72/20·4. .

i)

An.air termination along the outer perimeter of the roof is required and no part should be more than 5.0m from the nearest horizontal conductor,. except that an additional l.Om may be allowed for each metre by which the part to be protected is below the nearest conductor.

ii)

Horizontal conductors are not necessary on the parapets of the light well; a zone of protection of 60° is provided by the two adjacent horizontal conductors for structures less than 20.0m high. This principle does not apply to taller structures.

Figure 7.10 Air terminations for flat roofs at different levels

ETHIOPIAN BUILDING .CODE STANDARD

EBCS-10 1995

204

SECTION 7: EARTHING, BOND1NG AND LIGHTENING PROTECTION

:1' I.

Note:

D§ ..

. DC 60 m

DC

.1

i) Horizontal air termination conductors should be jointed at the interconnections. ii) Where PVC covered horizontal air termination conductors are used, bare vertical rods O.3m high should be fixed at each intersection and at intermediate positions along the horizontal conductors spaced no more than 10 apart.

Figure 7.11 Air terminations and down conductors for flat roof buildings where the air termination conductors have a PVC oversheath

Note:

The air termination network for a tall reinforced concrete or steel framed structure should be as follows: (a) Horizontal conductors on roofs from a IO.Om x 20.0m network. (b) There are bonds to steelwork at comers, at 20.0m intervals around the periphery and on the tower O.5m above the lower roof level. (c) Key bonding to the building steelwork.

Figure 7.12 Air terminations for tall conducting structures

205

EBCS-10 1995



Suspended air termination

See note 2

Mast

See"note 2

See note 2 Protected building

~Earth e l e c t r o d e - - - - - : (al Elevotlon


Proted.ed building

-


lbl Plan Kay

\

-

-

-

. - - X -

+ \ .........J

\

.

Zones of protection et m.,t\ Zon". of protee:t1on ., mlxlmum 18g of eerial conductor

~

.

r--+------jf---,

Protected building

.,.\

\ \ \

,

leI End elevation .nowlng zone. of protection

Note:

i) ii)

Where two or more suspended horizontal conductors are employed, a protective angle of 45· may be used in the space bounded by the conductors. Elsewhere, the protective angle is limited to 30·. To prevent flashover between mast/conductor and protected building, the minimum clearance distance has to be 2.0m or as under above governed by whichever is the greater. This clearance has to be .as above under maximum sag conditions

Figure 7.15 Air termination with twin suspended horizontal conductors & zone of protection for structure with explosive or highly flammable contents


----------

EBCS-10 1995

--~------------~--------.

208

I

I

i

~---_i

SEGTION 7: EARTHING, BONDING AND LIGHTENING PROTECTION I

A ..

Radius of b'lnd

8 inchus (203

~ml minimum.

Figure 7.16 Sharp bends

209

EBCS-10 1995



Nate:'

i) ii)

The down conductors may be natural port of the building framework or added strips or rods on external faces. On structures exceeding 20.0min height, down conductors should be spaced at not more 'than IO.Om . apart.

Figure 7.17 Pattern of down conductors for variousforrnsoftalI building

ETHIOPfANBUILDING CODE STANDARD

EBCS-10 1995

.210


ad maximum

Exceeding

.

d

ad

'

.~

Ib) Arrengement ,{heUs nOLpermissible

lal Perm'issible errangement

N·nt permisstble

I

t--Permissibte

·1 J

/:

l~~ij&

J

/c;)permissiblemethod ofteking 'conductor through eparllpet ,wlill

Idl·ROQ·tll.for,'down.tonductQQlin......tding. with .centilevlfrlld. up par floora

Figure 7.18 Re-entrant loops

21'1

EBCS-1'O 1995

ETHIOPIAN BUJUDINGCODE STANO!ARC


A= O:6~ m mini~um t

B=

3.ob

m minitqUm.

Figure 7.19 Earthtng in ftoist Clay

-~oi1.

Figure 7.19 Earthing in moist clay soil


EBCS-10 1995

212

Air ter mination bonded to steel reinforcing or steel frame of building

Air termination on roof.

D.own conductor~ I In these cases ~ steel reinforcing or steel friune of building)

hk-ri

cs -c,

.....

Ring earth eleetrod~ ....... J below ground level <, to improve earthing

<,

<,

.....,

Bonds to lift installations ot top and bottom of continuous rigid metal structure only

......_>00 ....' "

I

I

I

~ Earth

Ground level

electrode

NOTE. Air termiNltion mesh should bo not groeter thon 10 m X 20 m. Down conducton should be not mora than 10 m apart..

Figure 7.20 Lightning protection system for tall buildings (over 20.0m high) showing air terminations, down conductors, bonds to projections above roof


;[1 ~l

A =to.610 a

=: 13.00

ternate cC)D:figtiration

mminimum

mminimum .

Figure 7.21 Earthing in sandy er gravely soil

ETHIOPIAN BUILD1NG CODE STANDARD

EBCS~10

1995

214·


I

.....,/1 /. ~--~, ~ . . ~ ':--,

Eartb plate

" Loop conductor

Figure 7.22 Earthing in soilless than O.3m deep

215

EBCS-10 1995



'0

,d . ~.

. D'

, 0

o

o

,0

a

., ,

>

= r :

Concre te

o

.0:,

o•..o , '. Il

.

"

o .

~

~

.

,

,

. o

6

1. 0"

'.0

I

..

b • "

. :~.

" •

. I>

'

,

,.0:':, . •

•

.' 0

',~

,

"

4'

~'::;~.•'<::~".:

.

:.' :.~ "';~ g\~h)'i?Z'~~ ,'.:'. :.:.': t::'iit:·(s:,/{if,ur=t~·,

.~i.n;UZ"i;~

.

iJ'

((:~'-:( .'\':J :~··::Z;:·(;:<·,:· ~':.J~:;;:'~: ~~':

..,,~ . ::9. :'1'. '0 '0. ""." :.:.~::': 0: .'N.C'· ..~/:. ... '~':,

Asphalt

/

Asphalt

Concrete .

• v- ..

',~ .0 .. '

• 6 ~. :. .'

0

~"

.

~

.0'

~.

Figure 7.23 Example of an earth electrode seal for use within a tanked structure


EBCS-10 1995

216

SECTION 7: 'EARTHING, BONDING AND LIGHTENING PROTECTION

,Externlll! down

.7:)\Sl.\C4W

,condjctO~~I'

For cavity a11s provi"de sea ed tu e

.

~ ~

j]l_

I. . ~ •[J Lf--''--~

I

Test Jo n t - - - rr----1~I.."..=~~~mlll-:::=~:r.::I11--

)

.-,. .,. "" ,

Gas

"t _ ... ~

.,

.

"

;, ....... t ... ..I " ~/,

...r

'~

,

... "

",. \ , ".../'}"' ",,1 " , "" "I.....' ,,--..... .•,

-.- .. -,." .... -:\J.

l

...

':"-J

"""

'

\I ...

-=--1ler+i~e_p~pell.

....

Figure 7.24 Diagram showing bonding to services(gas, water and electricity)

..; '-'::::"'L··......L

NOTE.

Corrosion inhibitor to be, used

o~

all

Figure 7.25 Testing joints

217

EBCS-10 1995


ELECTRICAL INSTALLATION OF BUILDINGS'

1401+-+--H---

Bonding plate with a minimum contact area 'of 52 sq. mm

A ::: O.6lm rrum mum B= 3.00 m minimum

Figure 7.26 Earthing connection on structural framing


EBCS-10 1995

218

I I

~~~~~~-

ANNEX

A

(INFORMATIVE)

SYSTEM DESIGN

GENERAL CONSIDERATIONS The structure or, if it has not been built, the drawings and specifications should be examined taking into account the recommendations of this Section. In the case of structures having no suitable metallic members, it is important to consider th~ positioning of all the component parts of a ligh~ing protection system so that they perform their function without detracting from the appearance of the structure. Modern buildings use metal extensively in their structure and there is considerable benefit in utilizing such metal parts to maximize the number of parallel conducting paths. Often the lightning protection will be improved, worthwhile cost savings may result and the aesthetic appearance of the structure preserved. However, it 'should be borne in mind that a lightning strike to such a metal part, especially if it is beneath the surface, may damage the covering and cause masonry to fall. This' risk can be reduced, but not eliminated, by a surface-mounted lightning protection system. Examples of metal parts which should be incorporated into lightning protection systems are steel frames, concrete reinforcing bars, metal in or on a roof, window rails and handrails. Some metal within a structure may be used as a component of the lightning protection system; for example, _ sheet piling being in contact with the general mass of earth, may be used as an earth electrode and is unlikely to be improved, upon by the addition of rods or tapes. The whole structure should be provided with a fully interconnected lightening protection system; i.e., no part of the structure should be protected in isolation.

219

EBCS-10 1995

.-.-.-.-_._-----------~-

.-_.

-

..

ETHIOPIAN

__ .. .. ~

~_._-------_

__._-_._._-..-

.._---_ ..

---

BUI'~DING

CODE STANDARD

-- - - - - - - - -

ANNEX

B.1

B (CONSULTATION)

GENERAL

Consultation should take place between the designer of the lightning protection system and the interested parties indicated in Clauses B.2 through B.6 before and during all stages of design.

B.2

ARCIllTECT / ENGINEER

As far as practicable, the following should be determined: a)

Routing of all conductors. ~

b) General areas available for earth termination networks and reference earth electrodes.

c)

Materials(s) for conductor.

d) Extent of the work and the division of responsibility for primary fixings to the

structure, especially those affecting the water-tightness of the fabric, chiefly roofing. e)

Materials(s) to be used in the structure, especially for any continuous metal, e.g. stanchions or reinforcing.

f)

Use to which the structure is to be put.

g) Details of all metallic service pipes, rain-water system, rails and the like entering or leaving the structure or with the structure which may require bonding to the lightning protection system. h) Extent of any buried services which could affect the siting of the earth termination network(s). i)

Details of any equipment, apparatus, plant or the like to be installed within or near the building and which require bonding to the lightning protection system.


EBCS-10 1995

220

-----------


B.3 PUBLIC UTILITIES Agreement should be reached on the bonding of services to the lightning protection system. Because of the introduction of new materials and practices, reliance should not be placed on agreements reached for other structures.

B.4 FIRE AND SAFETY OFFICERS Agreement should be reached on: a)

the need for a lightning protection system on structures containing flammable or explosive materials;

b)

routes and materials( s) for construction of ducts and sealing at floors if internal conductor are being considered;

c)

the method of lightning protection to be adopted in the unlikely event of a structure having a flammable roof.

B.5 TELEVISION AND RADIO INSTALI,ERS Agreement should be reached on the need to bond antenna supports and screens of cables to the lightning protection system.

B.6 BUILDER Agreement should be reached on: . a)

the form, positions and numbers of primary fixings to be provided by the builder;

b)

any fixings provided by the lightning protection system contractor to be installed by the builder;

c)

the positions of conductor to be placed beneath the structure;

d)

whether any components of the lightning protection system are to be used during the construction phase, e.g. the permanent earth termination network could be used for earthing cranes, railway line, scaffolding, hoists and the like during construction;

221

EBCS-10 1995



e)

for steel framed structures, the numbers and positions of stanchions and the form of fixing to be made for the connection of earth terminations;

f)

whether metallic roof covering, where used, are suitable as part of the lightning protection system and the method of attachment of conductor to earth;

g)

the nature and location of services entering the structure above and below ground including railway lines, crane rails, wire ropeways, conveyor systems, television and radio antennas and their metal supports, metal flues, and flue-liners;

h)

the position and number of flag-masts, roof level plant rooms (i.e., lift motor rooms, ventilating, tanks and other salient features;

i)

the construction to be employed for roofs and walls in order to determine appropriate methods of fixing conductor, specifically with a view to maintaining the weather-tightness of the structure;

j)

possible penetration of a waterproofing membrane where earth terminations have to be sited beneath the structure, especially in 'urban' situations and in confined spaces on industrial sites; Note: The same general consideration applies to the reference earth electrode for use in initial and.

periodic testing.

k)

the provision of holes through the structures, parapets, cornices, etc to allow for the free passage of the down conductor;

l)

the provision of bonding connections to a steel frame, reinforcement bars and other metal;

m)

the most suitable choice of metal for the conductor taking account of corrosion, especially at bimetallic contacts;

n)

. the accessibility of test joints, protection by non-metallic casings from mechanical damage or pilferage, lowering of flag-masts or other removable objects, facilities for periodic inspection, especially on chimneys;

0)

the preparation of a drawing incorporating the above details and showing the positions of all conductors and of the main components.


EBCS-10 1995

222

SECTION

8

WIRING METHODS

8.1

SCOPE

(1) This Section applies to all wiring installation operating at 0.6/1.0kV or less except for:

conductors which form an integral part of factory built equipment; communication circuit, unless otherwise specified in Section 23; Class 2 circuits, unless otherwise specified in Section 10; community antenna distribution; radio and television installations, unless otherwise specified in Section 24; (e) optical fiber cables. (a) (b) (c) (d)

8.2

NORMATIVE REFERENCE

(1) The following references contain provisions which, through reference in this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings.

8.3

(a) C22.l:1992

Canadian Electrical Code Part I, Safety Standard for Electrical Installation, Sixteenth Edition

(b) BS 767:1992

The electricians Guide to the 16th Edition of the IEE Wiring Regulations, Second Edition, 1993


8.3.1 Methods of Installation (1) The methods of installation of wiring systems shall be as shown in Annex A.

ETHIOPlANBUILDING GODE STANDARD

EBCS-10 1995

223


(2) The Provisions in (1) above notwithstanding, the use of another method is not precluded, provided that compliance with this Code is maintained (3) A bare live conductor shall be installed on insulators. (4) Non-sheathed cables for fixed wiring shall be enclosed in conduits, ducting or trunking; however, this provision does not apply to a protective conductor.

8.3.2

Wiring in Ducts and Plenum Chambers

(1) No electrical equipment, unless specifically approved for the purpose, shall be installed in ducts used to transport dust, loose stock, or flammable vapours.

(2) No electrical equipment, unless specifically approved for the purpose, shall be installed in any duct used for vapour removal or for ventilation of commercial-type cooking equipment.

8.3.3

Underground Installations

(1) Direct buried conductors, cables, or raceways shall be installed to meet the minimum cover requirements shown in Table 8.1.

Table 8.1 Minimum cover requirements' for direct buried conductors, cables or raceways

L

Minimum cover [mm] Non~v8hlcular ar••s

WIring method

Conductors or cables

-

Over 750.0V

600

750

900

1000

750

600

1000

750

600

1000

._-

less

Over 750.0V

450

having " metal sheath or

.rmQur

Raolway

750.0Vor

750.0Vor

less Conduotors or cables not having a metal

sheath or armour

Vehicular areas

I

450

Minimum Clover means the distancebetweenthe top surfaceof the conductor, cable, or raceway andthe finished grade.

224

EBCS-10 1995


--~----

SECTION 8: WIRING METHODS

(2) The minimum cover requirements shall be permitted to be reduced by l50.0mm where mechanical protection is placed in t~e trench over the underground installation. (3) Mechanical protection shall consist of one of the following and, when in flat form, shall be wide enough to extend at least 50.0mm beyond the conductor, cables, or raceways on each side: (a) (b) (c) (d) (e)

Treated planking at least 38.0mm thick. Poured concrete at least 50.0mm thick. Concrete slabs at least 50.0mm thick. Concrete encasement at least 50.0mm thick. Other acceptable material.

(4) Raceways or cables, if located in rock, may be installed at a shallower depth entrenched into the rock in a trench not less than l50.0mm deep and grouted with concrete to the level of the rock surface. (5) Raceways may be installed directly beneath a concrete slab at grade level provided the concrete slab is not less than a nominal IOO.Omm in thickness, the location is adequately marked, and the raceway will not be subject to damage during or after installations. (6) Anyform of mechanical protection which may adversely affect the conductors or cable assemblies shall not be used. (7) Backfill containing large rock, paving materials, cinders, large or sharply angular substances, or corrosive material shall not be placed in an excavation where such materials may damage cables, raceways, or other substructures prevent adequate compaction of fill, or contribute to corrosion of cables, raceways, or other substructures.

8.3.4

Conductors in Holstways

(1) Where conductors other than those used to furnish energy to the lift or dumbwaiter are installed in hoistways, they shall be from mineral-insulated cable or armoured cables or be run in .rigid or flexible metal conduit or electrical metallic tubing. . (2) The cable, conduit, or tubing referred to in (1) above shall be: (a) securely fastened to the hoistway construction;


EBCS-10 1995

225


(b) arranged so that terminal-outlets or junction boxes open outside the hoistway except that pull boxes may be installed in long runs for the purpose of supporting or pulling in conductors. (3) (a) Main feeders for supplying power to elevators and dumbwaiters shall be instaIled outside the hoistway. (b) Only such electric wiring, raceways, and cables used directly in connection with the elevator or dumbwaiter, including wiring for signals, for communication with the car, for lighting, heating, air conditioning and ventilating the car, shall be permitted inside the hoistway.

8.4

CONDUCTORS

8.4.1

Types of Conductors

(1) Conductors installed in any location shall be suitable for the condition of use as indicated in Annex B of Section 4 for the particular location involved and with particular respect to the fol1wing (a) moisture

(b) (c) (d) (e)

corrosive action temperature degree of inclosure mechanical protection.

8.4.2 Radii of Bends in Conductors (1) The minimum internal radii of bends in conductors shall be as indicated in Table 8.2

226

EBCS-10 1995


~---_._----_.

I __

\


Table 8.2 Minimum internal radii of bends in cables for fixed wiring

t

Type of Insulation

Overall diameter

Bending factor

PVC PVC PVC Mineral

up to 10.0mm 10.0m to 25.0mm over 25.0mm any diametre

3 (2) 4 (3)

a at

Mineral-insulated cables may be bent at a minimum radius of three times the cable diameter provided that they will only be bent once.

Note:

8.4.3

i) The factor shown in the table is that by which the overall cable diameter must be multiplied to give the minimum inside' radius of the bend. ii) The figutes in brackets apply to unsheathed single-core stranded PVC cables when.installed in conduit, trunking or ducting.

Conductor Joints and Splices

(1) Unless made with solderless wire connectors, joints or splices in insulated conductors shall be soldered, but they shall first be made mechanically secured. (2) Joints or splices shall be covered with an insulation equivalent to that on the conductors being joined. (3) Joints or splices in wires and cables shall be accessible. (4) Splices in underground runs of cable, if required due to damage to the original installation, may be made: (a) in junction boxeswhich are located at least l.Om above grade and secured to buildings or to stub poles and suitably protected from mechanical damage; (b) notwithstanding the requirements in (3) above, by means of splicing devices or materials (kits) acceptable for direct earth burial.


EBCS-10 1995

22'1

-------.-------~._------------~-

I


8.4.4 Supporting of Conductors (l) Conductors shall be supported so that no injurious strain is imposed on the terminals of any electrical apparatus or devices or on joints or taps. Table 8.3 shows guidance on methods of support.

Table 8.3 Spacing of supports for cables in accessible position

Msximum spscing of clips [mmJ DV'lslI dismst'l of csbl, [mmJ

SlllBtll,d csbl" Horizontll

VertiCIl

Horizontll

VertiCIl

250 300 350 400

400 400 450 550

600 900 1500

800 1200 2000

:s:9 >9 s 15 > 15 s 20 >20 :s: 40 Note:

8.5

Min'lsl·insulst,d csbl"

For the spacing of supports for cables of overall diameter exceeding 40.0mm. andfor single-core cables having conductors of cross-sectional area 300.0mm2 and larger, the manufacturer's recommendations should be observed.

OPEN WIRING

8.5.1 Open and Clipped Direct (1) Sheathed cables clipped direct to or lying on non-metallic surface shall be installed in accordance with Installation Method 1 (see Annex A).

8.5.2 Spacing of Conductors (1) Spacing between conductors and adjacent surfaces shall be as indicated in Installation

Methods 12 and 13 (see Annex A). (2) In all locations, a separation of at least 25.0mm shall be maintained between conductors and adjacent metal piping or conducting materials.

228

EBCS-10 1995

ETHIOPIAN BUILDING CODE: STANDARD


8.5.3

Conductor Supports

(l) Conductors shall be supported rigidly on noncombustible, absorption resisting insulators.

(2) Conductors supported on solid knobs shall be securely tied thereto by tie wires having insulation of the same type as that on the conductors which they secure.

8.5.4

Spacing of Supports

(l) Sheathed and / or armoured cables installed in accessible positions and supported by clips shall not exceed the appropriate spacing value stated in Table 8.3.

8.6

EXPOSED WIRING ON EXTERIOR OF BUILDINGS AND BETWEEN BUILDINGS ON THE SAME PREMISES

8.6.1

Location of Conductors

(1) Where conductors are supported on or in close proximity to the exterior surfaces of buildings, they shall be installed and protected so that they shall not be hazardous to persons or be exposed to mechanical injury and they shall not, without special permission, be located at a height less than 4.5m from the ground.

8.6.2

Clearance of Conductors

(1) Conductors which pass over roofs shall be located or guarded so that they cannot be reached by a person standing on a fire escape, flat roof, or other portion of a building. (2) Such conductors in (1) above shall at least be 2.5m above the highest point of a flat roof or a roof that can be readily walked upon and at least 1.0m above peaked roofs or the highest point of such roofs that can be readily walked upon; however, by special permission; they may be located less than 2.5m, but not less than 2.0m, above the highest point of a flat roof or roofs so that the latter can be readily walked upon.

8.6.3

Power Supply Conductors

(1) The conductors of a power supply system attached to the exterior surfaces of buildings shall be at least 300.0mm from the conductors of a communication' system unless one system is in conduit or is permanently separated from other systems.

"

"


.......

'

EBCS-10 1995

229

~~~

--_._---


8.7

BARE BUS BARS AND RISERS

(1) Bare conductors shall not be used as main risers or feeders in buildings unless, special permission is obtained. (2) Special permission shall not be granted unless: (a) the building is of noncombustible construction; (b) the conductors are placed in a chase, channel, or shaft located or guarded so that the conductors are inaccessible; (c) the premises do not constitute a hazardous location; (d) suitable cut-offs to protect against the vertical spread of fire are provided where floors are pierced; (e) the mechanical and electrical features of the installation and the conductor supports are appropriate to the operating and maintenance conditions likely to occur, the following requirements being used in the case of bus bars rated 1200.0A or less: Note:

i) Where flat bus bars 6.25mm or less in thickness are used, the continuous current rating shall not exceed 1.6AJmm2 of cross-sectional area of copper bus bar or 1.12AJmm2 in the case of aluminium bus bars. ii) Bus bar supports shall be spaced not more than 750.0mm apart, with minimum clearance across insulating surface between bars of opposites polarity of not less than 50.0mm, and 25.0mm between bus bars and any earthed surface.

8.8

INSTALLATION OF BOXES, CABINETS, OUTLETS AND TERMINAL FITTINGS

8.8.1 Number of Outlets per Circuit (1) There shall be no more than 12 outlets on any 2-wire branch circuit except as permitted by other Sections of this Code. (2) Such outlets in (1) above shall be considered to be rated at not less than l.OA per outlet except as permitted by (3) below.

(3) Where the connected load is known, the number of outlets may exceed 12 provided the load current does not exceed 80% of the rating of the overcurrent device protecting the circuit.

230

EBCS-10 1995

-------_._._--------.-------


-- ._._.__ .__

------~------,----~·-·-~--···_--·-·-------c----

~_.-

.

,

_

SECTiON 8: WIRING METHODS

8.8.2

Outlet Boxes

(l) A box or an equivalent device shall be installed at every point of outlet, switch or junction

of conduit and at every point of outlet and switch of concealed knob-and-tube work. (2) Nonmetallic outlet boxes shall not be used in wiring methods using metal raceways, armoured or metal sheathed cable, except where the boxes are provided with bonding connection between all conductor entry openings. (3) The box shall be provided with a cover or a fixture canopy. (4) At least 150.0mm of free conductor shall be left at each outlet for making of joints 'or connection of fixtures unless the conductors are intended to loop through lamp holders, socket outlets, or similar devices without joints. (5) Ceiling outlet boxes in concrete slab construction shall have knockouts spaced above the free or lower edge of the boxes a distance of at least twice the diameter of the steel reinforcing bars so that conduit entering the knockouts shall clear the bars without offsetting. (6) Boxes and fittings shall be firmly secured to studs, joists or similar fixed structural units.

8.8.3

Conductors in Boxes

(1) Boxes shall be of sufficient size to provide usable space for all insulated conductors

contained in the box. (2) Conductors which are connected to different power or distribution transformers or other different sources uf voltage shall not be installed in the same box, cabinet or fitting.

8.8.4

Terminal Fittings

(1) Where conductors are run from the ends of conduit, armoured cable surface raceways or non metallic sheathed cable to appliances or open wiring installation, an outlet fitting or terminal fitting may be used instead of the box required in Clause 8.8.2, and the conductors shall be run without splice, tap or joint within the fitting. (2) The fittings in (1) above shall have a separately bushed hole for each conductor. (3) The fittings ill (1) above shall not be used at outlets for fixtures.


EBCS-10 1995

231 .-------'

----~~_.- .. - - _ . _ - - - - - - - - -


I,

8.9

CABLES, CONDUCTORS AND WIRING METHODS

(1) Every cable operating at low voltage shalf be selected in accordance with Section 4 of this

Code. (2) The method of installation of cables and conductors shall be subject to the provision of Clause 8.3.1.

1232

EBCS-10 1995


A (NORMATIVE)

ANNEX

SCHEDULE OF METHODS OF INSTALLATION OF CABLES Note:

i) The methods of installation distinguished by bold type are reference methods for which the current carrying capacity given in Annex B, Tables B.I through BA5, Section 4, have been determined. ii) For the other methods, an indication is given of the appropriate reference method having values of current-carrying capacity which can safely be applied.

Installation method Examples

Number

DescrlJ'tion

1

2

Open and clipped direct:

1

Appropriate Reference Method for determining current-carrying capacity

3

I

:'~'I®J,: ;~h~0 rii/Y. , 8 / .Tif)

Sheathed cables clipped direct to or lying

on a non-metallic surface ' :,'.~ ,

'I

4

I

- - - - - - - - - - - - - - - - - - - - - ~... _~-

:'j'

'.

.""

...

".'

('..

Method 1

-------

Cables embedded direct In building materials: Sheathed cables embedded directly in masonry, brickwork, concrete, plaster or the like (other than thermally Insulating materials)

2

Method 1

In conduit:

3

Single-core non-sheathed cables in metallic or non-metallic conduit on 'a wall or ceiling

4

Single-core non-sheathed cables in metallic or non-metallic conduit in a thermally insulating wall or above a thermally insulating ceiling, the conduit being in contact with a thermally conductive surface on one sidet

5

Multicore cables having non-metallic sheath, in metallic or non-metallic conduit on a wall or ceiling.

_I~

Method 3

I

r':

Method 4

~

~' ~

~

~ ~

em

Method 3 II

t The wall is assumed to consist of an outer weatherproof skin, thermal insulation and an inner skin of a plaster board or a wood-like material having a thermal conductance not less than IOw/m2K. The conduit is flxed so as to be close to, but not necessarily touching, the inner skin. Heat from the cables is assumed to escape through the inner skin only.


EBCS-10 1995

233


Installation method Number

Oescription

1

2

6

Sheathed cables in conduit in a thermally insulating wall etc. (otherwise as Reference Method 4)

Intrunking: 8

9

10

~

Cables in conduit embedded in masonry, brickwork, concrete, plaster or the like (other than thermally insulating materials)

7

I

Examples

I

3

4

_.c:Q -j ;"//

/,//

;:~~;

.......

:~

/~--:.~ :::::;,.:~
..

I

-~-

- - - , -_ _ [_

Method 4

~ .~_~_ Method 3

//

~...,.

I


..

"¥" ,]

1- Cables

in trunking on a wall or I suspended in the air

Method 3

Cables in flush floor trunking

Method 3

Single-core cable in skirting trunking

£:~l

....

_.~._------

Method 3

On trays:

11

Sheathed cables on a perforated

cable tray, bunched and

unenclosed. A perforated cable

tray is considered as a tray in Which the holes occupy at least 30% of the surface area

Method 11

In free air, on cleats, brackets or a ladder

12

Sh'b'athed single-core cables in free air (any supporting metalwork I nder the cables occupying less than 10% of the plan area): Two or thr~e cables vertically one above the other, minimum distance between cable surfaces equal tc. the overall cable diameter· (OJ; distance from the wall not less than 0.50 •.

Method 12

Two or three cables horizontally, with spacings as above three cables in trefoil, distance between wall and surface of nearest cable 0.50. or nearest cables 0.750.

234

EBCS-10 1995



Installation method Number

Description

1

2

Examples


3

4

In free air, on cleats, brackets or a ladder 13

14

Sheathed multlcore cables on ladder or brackets, separation greater than 20. Sheathed multicore cables in free air distance between wall and cable surface not less than 0.30. Any supporting metalwork under the cables occupying less than 10% the plan area Cables suspended from incorporating a catenary wire

or

~ I

~ e -- ...

Cables in building voids:

15

Sheathed cables installed directly in a thermally insulating wall or above a thermally insulating ceiling, the cable being In contact with a thermally conductive surface on one side (otherwise as Ref Method No 4) Sheathed cables In ducts or voids formed by the building structure, other than thermally Insulating materials

-

..

~

-c o.J0t' min

Method 13

o,

W

.

Method 12 or 13, as appropriate

-_.~~

Method 4

~

(

Method 4 Where the cable has a diameter D. or a perimeter not greater than 200. Method 3 Where the duct has either a diameter greater than 50. or a perimeter greater than 200.

16

Notes: ~Where the perimeter is greater than 600., installation Methods 18 to 20, as appropriate, should be used. ii) D. Is the overall cable diameter; for groups of cables D. is the sum of the cable diameters.


EBCS-10 1995

235

---------_._--------

--------------

.~--

ELECTR,ICAL INSTALLATION OF BUILDtNGS

Installation method Examples Number

Description

1

3

2

Appropriate Reference Method for determining current-carrying capacity 4

Cable in trenches:

17

I

-c-ba-I e-s---supp-rt-~o o-ed ---the-w-n -- -aII T===:::::::===============-T---------

Ii

of an open or ventilated trench, with spacin~s Indicated for Reference Method 12 or 13 as appropriate

@

~~- n~nn~V~ ?7~ ~ _:LZILfL'-

r

~ ~ v

7?/7/,

;t--====t

~979/97~

Cables In enclosed trench 450.0mm wide by 600.0mm

deep (minimum dimensions)

including 100.0mm cover

19

Method 12 or 13, as appropriate

_~/////
Cables in enclosed trench 450.0mm wide by 300.0mm


including100.0mm cover

18

,

-i~~

Two single-core cables with

surfaces separated by a

minimum of one cable

diameter.

Three single-core cables in

trefoil and touching throughout. . Multlcore cables or groups of single-core cables with surfaces minimum of 50.0mm Single-core cables arranged

in flat groups of two or three

on the vertical

trench wall with surfaces separated by one diameter with a minimum distance' of 50.0mm between groups.

Method 18. Use rating

factors in Table A.3, Section 4.

Method 19. Use rating factors in Table A.3, Section 4~

Multicore cables Installed with surfaces separated by a mlnlmum' of 75.0mm. All cables spaced at least 25.0mm from the trench wall Cables in enclosed trench 600.0mm wide by 760.0mm


including 100.0mm cover

Single-core cables arranged

in groups of two or three in

flat formation with the

surfaces separated by one diameter or intrefoil formation with cables touching.

20 Groups separated by a mlnlrnum! of 75.0mm either horizontally or vertically.

Method 20. Use rating factors in Table A.3, Section 4.

All cables spaced at least 25.0mm from the trench wall.

t

Larger spacing to be used where practicable,

236

EBCS-10 1995


.-.-

...

~--.----.----

SECTION

9

PROTECTION AND CONTROL

9.1

SCOPE

(1) This Section covers the protection and control of electrical circuits and apparatus installed in accordance with the requirements of this Code.

9.2


(1) The following references contain provisions which, through reference in this text, constitute

provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings. (a) C22.1: 1992

(b) BS 7671:1992

Canadian Electrical Code Part I, Safety Standard for Electrical Installation, Sixteenth Edition. Requirements for Electrical Regulations, Sixteenth Edition.

9.3


9.3.1

Protective and Control Devices

Installation,IEE

Wiring

(1) Every electrical apparatus and unearthed conductors shall be protected by one or more devices as may be necessary for automatic and/or manual interruption of the supply in the event of any fault and shall be provided with: (a) protection against fault current to break any fault current in a circuit before such current causes danger due to thermal or mechanical effects produced in those conductors or the associated connection; (b) protection against overload current to break any such current flowing in the circuit conductors before such a current causes a temperature rise detrimental to insulation, joints, termination or the surroundings of the conductors;

ETHIOPIAN BUILDING CODE STANOARD

EBCS-10 1995

237


(c) protection against under-voltage which when necessary will open the circuit, where a reduction in voltage, or loss and subsequent restoration of voltage could cause danger; (d) manually-operable control device which will safely disconnect all unearthed conductors of the circuit at the point of supply simultaneously; and (e) protection against earth fault in accordance with Clause 9.4.2. 9.3.2

Types and Ratings of Protective and Control Devices

(1) Circuit breakers, fuses, and switches shall be of type and ratings acceptable to the department in charge of inspection.

(2) Overcurrent protective devices shall ensure safe operation and shall have interrupting capacity sufficient for the voltage employed and for the anticipated fault current which must be interrupted. 9.4

PROTECTIVE DEVICES

9.4.1

Overcurrent Devices

(1) Each unearthed conductor shall be protected by an overcurrent device at the point where it

receives its supply of current and at each point where the size of conductor is decreased, except that such protection may be omitted where: (a) the overcurrent device in a larger conductor properly protects the smaller conductor; (b) the smaller conductor is not over 3.0m long and does not extend beyond the switchboard, panelboard, control device which it supplies; or (c) the smaller conductor has an ampacity not less than one-third that ofthe larger conductor from which it is supplied. (2) The rating or setting of overcurrent devices shall not exceed the allowable ampacity of the conductors which they protect except: (a) where a fuse or circuit breaker having a rating or setting of the same value as the ampacity of the conductor is not available, the ratings or settings given in Table 9.1 may be used; (b) in case of equipment wire, flexible cord, and tinsel cord, which will be considered as being protected by 16.0A overcurrent devices; or (c) as provided for by other Clauses of this Code.

238

EBCS-10 1995


I"

SECTION 9: PROTECTION AND CONTROL

(3) Overcurrent devices shall be enclosed in cutout boxes or cabinets unless they form a part of an approved assembly which affords equivalent protection, or unless mounted on switchboards, paneboards, or controllers located in room or enclosures free from easily ignitible material and dampness, and accessible only to authorized persons. (4) Overcurrent devices shall not be connected in parallel in circuits of 1000.OV or less unless otherwise they are factory-assembled in parallel as a single unit. 9.4.2

Earth-Fault Protection

(1) Earth-fault protection shall be provided to de-energize all normally earthed conductors of a faulted circuit in the event of an earth fault in those conductors as follows:

(a) in solidly earthed circuits rated more than 230.0V-to-earth, less than 1000.0V phase-to phase and 1000.OA or more; and (b) in solidly earthed circuits rated 230.0V-to-earth or less and 2000.0A or more. (2) The maximum setting of the earth-fault protection shall be 1200.0A and the maximum time delay shall be 1.0s for earth fault currents equal to or greater than 3000.0A. (3) The ampere rating of the circuits referred to in (1) above shall be considered to be: (a) the rating of the largest fuse that can be installed in a fusible disconnecting device; (b) the highest trip setting for which the actual overcurrent device installed in a circuit breaker is rated or can he adjusted; or (c) the ampacity of the main conductor feeding the devices in cases where no main disconnecting device is provided. (4) Earth-fault protection shall be provided by: (a) an overcurrent device which incorporates earth-fault protection; (b) earth-fault tripping system comprising a sensor or sensors, relay and auxiliary tripping mechanism; or (c) other appropriate means.


EBCS-10 1995

239


9.S

FUSES

(1) Only fuses and fuse holders of proper rating shall be used, and no bridging or short circuiting of either component shall be permitted. (2) Where plug fuses are used in branch circuits, they shall be of such a type and so installed that they are non-interchangeable with a fuse of larger rating. (3) A fuse having a fuse link which is likely to be removed or replaced while the supply is connected shall be of a type such that it can be removed or replaced without danger.

9.6

CIRCUIT BREAKERS

(1) Circuit breakers shall be of the trip-free type. (2) Indication shall be provided at the circuit breaker and at the point of operation to show whether the circuit breaker is open or closed. (3) Circuit breakers shall open the circuit in all unearthed conductors by the manual operation of a single handle and by the action of overcurrent. (4) Circuit breakers shall be of such design that any alteration by the user of either the tripping current or the time will be difficult. (5) 'Circuit breakers shall be equipped with tripping elements as specified in Table 9.2.

9.7

CONTROL DEVICES

(1) Control devices shall haveratings suitable for the connected load of the circuits which they control and, with the exception of isolating switches, shall be capable of safely establishing and interrupting such loads. (2) Control devices used in combination with overcurrent devices or overload devices for. the control of circuits or apparatus shall be connected so that the overcurrent or overload devices will be dead when the control device is in the open position, except where this is impracticable. (3) Control devices, with the exception of isolating switches, shall be readily accessible.

240

EBCS-10 1995


._._------------~~~-


(4) Control devices, unless located or guarded so as to render them inaccessible to unauthorized persons and to prevent fire hazards, shall have all current-carrying parts in enclosures of metal 01' other fire-resisting material.

(5) Where electrical equipment is supplied by two or more different transformers or other sources of voltage, then: (a) a single disconnecting means, which will effectively isolate all unearthed conductor supplying the equipment, shall be provided integral with or adjacent to the equipment; or (b) each supply circuit shall be provided with a disconnecting means integral with or adjacent to the equipment, and the disconnecting means shall be grouped together.

9.8

SWITCHES

(1) Single-throw knife switches shall be mounted with their bases in a vertical plane so that gravitational force will not tend to close them. (2) (a) Double-throw knife switches may be mounted so that the throw will be either vertical or horizontal. (b) If the throw in (1) above is vertical, a positive locking device or stop shall be provided to ensure that the blades remain in the open position when so set unless it is not intended that the switch be left in the open position. (3) Manual single-throw switches, circuit breakers, or magnetic switches, shall be connected so that the bases or moving contacts will be dead when the device is in the open position except when other conditions make this requirement unnecessary.

9.9

PROTECTION AND CONTROL OF MISCELLANEOUS APPARATUS

(I) Socket outlets shall not be connected to a branch circuit having overcurrent protection rated or set at more than the ampere rating of the socket outlets except as permitted by other Sections of this Code. (2) Portable appliances need not be equipped with additional control devices where the appliances are:


EBCS:.10 1995

241


(a) rated at not more than 1500.0W; and (b) provided with cord connectors, attachment plugs or other means by which they can be disconnected readily from the circuits. (3) Where switches are used to control an outlet or outlets from more than one point, the switches shall be wired and connected so that the earthed conductor runs directly to the outlet or outlets controlled by the switches. (4) Except for panel boards where more than 90% of the overcurrent devices supply feeders or motor branch circuits, every panel board shall be protected on the supply side by overcurrent devices having a rating not greater than that of the panel board. (5) Transfer equipment for standby power systems shall prevent the inadvertent interconnection of normal and standby sources of supply in.any operation of the transfer equipment.

242

EBCS-10 1995



Table 9.1 Rating or setting of overcurrent devices protecting conductors (For general use where not otherwise specifically provided for)

Ampacity of conductors

Rating or setting permitted [A] Fuse

Circuit breaker

0-16

16

16

17-20

20

20

21-25

25

32

26-32

32

32

33-40

40

40

41-50

50

50

51-63

63

63

64-80

80

100

91-100

100

100

101-110

110

125

111-125

125

125

126-150

150

150

151-175

175

175

176-200

200

200

201-225

225

225

226-250

250

250

251-275

300

300

276-300

300

300

301-325

350

350

326-350

350

350

351-400

400

400

401-450

450

450

451-500

500

500

501-525

600

600

526-550

600

600

551-600

600

600


EBCS-10 1995

243

tv H:>o H:>o I

Table 9.2 Overcurrent trip coils for circuit breakers and overload devices for protecting motors

I,

For motor overload protection

For circuit protection t

Number and location of overload

Number and Iccation of overcurrent devices (Trip Coils)

System

devices such

as

trip coils relays, or

Kind of motor

thermal ~ cutouts 3-trip coils, one in each conductor

3-trip coils, one in each phase

3-wire, 3-phase a.c., unearthed or with earthed neutral

3

one in each phase not to be cqpnected in any neutral conductor

3-phase a.c.

4-wire, 3-phase a.c.

I

i

2-trip coils, one each phase

t

~

4--wire, ~2-phase a.c., unearthed

2-trip coils, one in each outside conductor


4-trip coils, one in each unearthed conductor

4-wire, 2-phase a.c., with earthed neutral



2-trip coils, one in each outside

3-wire, 1-phase a.c. or d.c.

t-trip coil in each unearthed conductor

2-wire a.c. or d.c., unearthed or with one conductor eerthedt t


3-wire, 1-phase a.c. or d.c., with earthed neutral

2

one in each phase, not to be connected in any neutral or earthed conductor

2-phase a.c.

1

in any conductor except a neutral or earthed conductor

1-phase a.c. or d.c.

This will not preclude the use of other arangements which will provide equivalent protection.

tt This will not prevent the use of one single-pole circuit breaker in each conductor for the protection of an unearthed 2-wire circuit

~

SECTION

10

CLASS 1 AND CLASS 2 CIRCUITS

10.1

SCOPE

(1) This Section covers remote-control, signalling and power-limited circuits that are not integral parts of a device or lUI appliance. (2) This Section does not apply to communication circuits that are dealt with in Section 23. Note:

The circuits described in this Section are characterized by usage and power limitation which differentiate themfrom electric lightand powercircuitsand,therefore, alternative requirements tothose of otherreievant Sections ofthis Codewithregardto minimum wiresizes,de-rating factors, overcurrent protection, insulation requirements, wiring method, and material are deemed necessary.

10.2


(1) The following references contain provisions which, through reference in this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings. (a) NFPA701NEC: 1986 National Fire Protection Association!American National Electrical Code, 1987 Edition. (b) C22.l:1992

10.3

Canadian Electrical Code Part I,Safety Standard for Electrical Installations, Sixteenth Edition.

CLASSIFICATION

10.3.1 General (io) Circuits covered by this Section are those portion of the wiring system between the load side of the overcurrent device or the power-limited supply and all connected equipment, and shall be Class 1 or Class 2 as defined below: (a) Class 1 - Circuits which are supplied from sources having limitation in accordance with Clause 1004.1.


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(b) Class 2 -. Circuits which are supplied from sources having limitation in accordance with Clause 10.5.1.

10.3.2 Class 1 Extra-Low-Voltage Power Circuits (I) Circuits which are neither remote-control circuits nor signal circuits, but which operate at not more than 30.0Y where the current is not limited in accordance with Clause 10.5.1 and which are supplied from a transformer or other device restricted in its rated output to 1000.OYA shall be clasefied as extra-low-voltage power circuits and shall be considered to be Class I circuits.

10.3.3 Class 2 Low-Energy Power Circuits (I) Circuits which are neither remote-control circuits nor signal circuits but in which the current is limited in accordance with Clause 10.5.1 shall be clasified as low-energy power circuits and shall be considered to be Class 2 circuits.

10.3.4 Hazardous Location (I) Where the circuits or apparatus within the scope of this Section are installed in hazardous locations, theyshall also comply with the applicable Clauses of Section 12.

10.3.5 Circuits to Safety Control Devices (I) Where the failure to operate a remote-control circuit to a safety control device will introduce a direct fire or life hazard, the remote-control circuits shall be deemed to be 'a Class I circuit.

10.3.6 Circuits in Communication Cables (I) Class I circuits shall not be run in the same cable with communication circuits. (2) Class 2 remote-control and Signal Circuits or parts thereof which use conductor in a cable assembly with other conductors forming parts of communication circuits are, for the purpose of this Code, deemed to be communication circuits and shall conform to the requirements of applicable Clauses of Section 23. .

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SECTION 10: CLASS 1 AND CLASS 2 CIRCUITS_ " 10.4

CLASS, 1 CIRCUITS

10.4.1 Limitation of Class 1 Circuits (1) Class 1 extra-low-voltage power circuits shall be supplied from a source having a rated output of not more than"30.0V and 1OOO.OVA. (2) Class 1 remote-control and signal

~ircuits

shall be supplied by a source not exceeding

600~OV.

10.4.2 Methods of Installation for Class 1 Circuits (1) The equipment and conductor of Class 1 circuits shall be installed in accordance with the requirements of other appropriate Sections of this Code, except as provided in Clauses 10.4.5 through ~0.4.10.

10.4.3 Overeurrent Protection of Class 1 Circuits (1) Conductors of Class 1 circuits shall be protected against overcurrent in accordance with

Section 9 of this Code, except: (a) where other Clauses of this Code specifically permit or require other overcurrent protection; or . 2 (b) where the conductors are of 1.0mm copper and extend beyond the equipment enclosure, they shall be protected by overcurrent devices rated at a maximum of 5.0A and 1O.0A, respectively. (2) Where overcurrent protection is installed at the secondary terminals of the transformer and the transformer is suitably enclosed, no overcurrent protection is required on the primary side other than the normal overcurrent protection of the branch circuit supplying the transformer,

10.4.4 Location of Overcurrent Devices in Clpss 1 Circuits (1) In Class 1 circuits, the overcurrent devices shall be located at the point where the conductor to be protected receives' its supply. (2) The overcurrent device may be an.integralpart of the power supply.


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10.4.5 Class 1 Extra-Low-Voltage Power Orc.it Sources Including Transformers (1) To comply with the lOOO.OVA limitation, Class 1 extra-low-voltage power circuit sources including transformers shall not exceed-a maximum power output of 2500.0VA; and the product ofthe maximum current and maximum voltage shall not exceedI OOOO.OVA with the overcurrent protection by-passed.

10.4.6 Conductor Material and Sizes (1) Copper conductors smaller than 2.5mm2 may be used in Class 1 circuits if:

(a) installed in a raceway; (b) installed in a cable assembly; or (c) within a flexible oord in accordance with Section 4.6. (2) Subject to the conditions specified in (1) above, conductors shall not be smaller than: a) 1.5mm2 for individual conductors pulled in raceways; b) 1.0mm2 for individual conductors laid in raceways, and c) 1.0mm2 for an integral assembly of two or more conductors. 10.4.7 Insulated Conductors for Class 1 Wiring (1) Where conductors larger than I.5mm 2 copper are used in a Class 1 circuit, they shall be of any type shown in Annex B of Section 4.

(2) Where conductor of l.Dmm! or l.5mm2 copper are used in a Class 1 circuit, they shall be equipment wire of the type suitable for such use as shown in Annex B of Section 4. 10.4.8 Conductors of Different Circuits in the Same Enclosure, Cable, or Raceway (1) Different Class 1 circuits shall be permitted to occupy the same enclosure, cable or raceway without regard to whether the individual circuits are alternating current or direct current, provided all conductors are insulated for the maximum voltage of any conductor in the enclosure, cable or raceway. (2) Power supply conductors and Class 1 circuit conductors shall not be permitted in the same enclosure, cable, or raceway except when connected to the same equipment; and all conductors are insulated for the maximum voltage of any conductor in the enclosure, cable, or raceway.

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SECTION 10: CLASS 1 AND CLASS 2 CIRCUITS

10.4.9 Mechanical Protection of Remote-Control Circuits (1) Where mechanical damage to a remote-control circuit would result in a hazardous condition all conductors of such remote-control circuits shall be installed in conduits, electrical metallic tubing, or be otherwise suitably protected from mechanical injury or other injurious condition such as moisture, excessive heat or corrosive action. ~0.4.10

Class 1 Circuits Extending Aerially beyond a Building

(1) Class 1 circuits which extend aerially beyond a building shall comply with the requirement of Section 8.6.

10.5

CLASS 2 CIRCUITS

10.5.1 Limitations of Class 2 Circuits (1) Class 2 circuits, depending upon the voltage, shall have currents limited as follows:

a) 0 to 20. OV: Circuits in which the open-circuit voltage does not exceed 20.0V shall have overcurrent protection rated at not more than 5.0A except that overcurrent protection shall not be required where the current is supplied from: i)

primary batteries which, under short circuit, will not supply a current exceeding 7.5A after l.Omin; ii) a Class 2 circuit transformer; iii) a device having characteristics which will limit the current under normal operating conditions or under fault conditions to a value not exceeding 5.0A; or iv) a device having a Class 2 output. b) Over 20.0V but not exceeding 30.0V: Circuits in which the open-circuit voltage exceeds 20.0V, but does not exceed 30.0V, shall have an overcurrent protection rating not exceeding lOON amperes, where V is the open-circuit voltage, except that the. overcurrent protection shall not be required where the current is supplied from: i) primary batteries which under short circuit will not supply a current exceeding 5.0A after I.Omin; ii) a Class 2 circuit transformer; iii) a device having characteristics which will limit the current under normal operating conditions or under fault conditions to a value not exceeding lOON amperes, where V is the open-circuit voltage; or iv) a device having a Class 2 output.


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c) Over 30. OJ' but not exceeding 60.0V: Circuits in which the open circuit voltage exceeds 30.0V, but does not exceed 60.0V, shall have an.. overeurrent protection rating not exceeding lOON ampers, where V is the open-circuit voltage, except that the overcurrent protection shall not be required where the current is supplied from: i) a Class 2 circuit transformer; or ii) a device having characteristics which will limit the current under normal operating conditions or under fault conditions to a value not exceeding lOON amperes, where V is the open-circuit voltage. d) Over 60.0V but not exceeding 150.0V: Circuits in which the open-circuit voltage exceeds 60.0V, but does not exceed 150.0V, shall have an overcurrent protection rating not exceeding lOON amperes, where V is the open-circuit voltage,and, in addition, shall be equipped with current-limiting means other than overcurrent protection, which will limit the current, either under normal operating conditions or under fault conditions, to a value not exceeding lOON amperes, where V is the open-circuit voltage. (2) Transformer devices supplying Class 2 circuits shall be restricted in their rated output to not exceeding 1OO.OVA. (3) A device having energy-limiting characteristics may consist of a series resistors of suitable rating or other similar device. ·(4) A Class 2 power supply shall not be connected in series or parallel with another Class 2 power source.

10.5.2 Methods ofInstallation on Supply Side of Overcurrent Protection or Transformers or Other Devices for Class 2 Circuits (1) In Class 2 circuits, the conductors and equipment on the supply side of overcurrent protectidh, transformers, or current-limiting devices shall be installed in accordance with the requirements of other appropriate Sections of this Code.

10.5.3 Marking (1) A Class 2 power supply unit shall have permanent markings which shall be readily visible after installation to indicate the class of supply and its electrical rating.

10.5.4 Overcurrent Protection for Class 2 Circuits (1) Overcurrent protection of different ratings shall not be of an interchangeable type.

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SECTION 10: CLASS 1 AND CLASS 2 CIRCUITS (2) The overcurrent protection maybe an integral part of a transformer or other power-supply device.

10.5.5 Location of Overcurrent Devices (1) Overcurrent devices shall be located at the point where the conductor to be protected receives its suppl;V'

10.5.6.tonductors for Class 2 Circuit Wiring (1) Conductors for use in Class 2 circuits shall be of the type suitable for the application as indicated in Annex B, Section 4. (2) The maximum allowable current shall be as listed in Annex B, Section 4, for sizes 1.5~1n2 and smaller, but in no case shall it exceed the current limitations of Clause lO.5.1.

10.5.7 Separation of Class 2 Circuit Conductors from Other Circuits (1) Conductors of Class 2 circuits shall be separated at least 50.0mm from insulated conductors of electric lighting, power or Class 1 circuits operating at 380.0V or less, and shall be separated at least 600.0mm from any insulated conductors of electric lighting, power or Class 1 circuits operating at more than 380.0V unlessfor both conditions effective separation is afford by use of: a) metal raceways for the Class 2 circuits or for the electric lighting, power and Class 1 circuits subject to the metal raceway being bonded to earth; b) metal sheathed or armoured cable for the electric lighting, power and Class 1 circuit conductors subject to the sheath. or armour being bonded to earth; c) nonmetallic sheathed cable for the electric lighting, power and Class 1 circuits operating at 380.0V or less; or d) nonmetallic conduit, electrical nonmetallic tubing, insulated tubing or equivalent, in addition to the insulation on the Class 2 circuit conductors or the electric lighting, power and Class 1 circuit conductors. (2) Where the electric lighting or power conductors are bare, all Class 2 circuit conductors in the same room or space shall be enclosed in a metal raceway that is bonded to earth and no opening, such as an outlet box, may be located withinZflm of the bare conductors ifup to and including l5.0kV or within 3.0m of bare conductors above l5.0kV. (3) Unless the conductors of the Class 2 circuits are separated from the conductors of electric , lighting, power and.Class 1 circuits by an acceptable barrier, the conductors in Class 2 circuits


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shall not be placed in any raceway, compartment, outlet box, junction box or similar fitting with the conductor of electric lighting, power or Class 1 circuits.

10.5.8 Conductors of Different Class 2 Circuits in the Same Cable, Enclosure, or Raceway 0) Conductors of two or more Class 2 circuits shall be permitted within the same cable, enclosure or raceway provided all conductors in the cable, enclosure, or raceway are insulated for the maximum voltage of any conductor.

10.5.9 Penetration of a Fire Separation (1) Conductors of a Class 2 circuit extending through a fire separation shall be so installed as to limit fire spread. 10.5.10 Conductors in Vertical Shafts and Hoistways

(1) Class 2 conductors and cable installed in a vertical shaft or hoistway shall comply with the requirements of Section 18. 10.5.11 Class 2 Conductors and Equipment in Ducts and Plenum Chambers

(1) Class 2 conductors and equipment shall not be placed in ducts or plenum chambers except as permitted by Clause 8.3.2. 10.5.12 Equipment Located on the Load Siljte of Overcurrent Protection, Transformers, or

Current-Limiting Devices for Class 2 Circuits (l) Equipment located on the load side of overcurrent protection, transformers, or current limiting devices for Class 2 circuits shall comply with the following:

a) For Class 2 circuits operating at 30.0V or less, alternating current or direct current, it shall be acceptable for the particular application. b) For Class 2 circuits operating at more than 30.0V, alternating current or direct current, it shall be arranged so that no live parts are accessible to unauthorized persons. (2) Notwithstanding the provisions of (Ia) above, lighting fixtures and thermostats incorporating heat anticipators, located on the load side of overcurrent protection, Class 2 transformers, or current-limiting devices shall be approved when connected to Class 2 circuits operating at 30.0V or less.

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SECTION 10: CLASS 1 AND CLASS 2 CIRCUITS

. 10.5.13

Class 2 Circuits Extending Beyond a Building

(1) Where Class 2 circuits extend beyond a building and are run in such a manner as to be subjected to accidental contact with lighting or power conductors operating at a voltage exceeding 380.0V between conductors of the Class 2 circuits, they shall also meet the requirements of Section 23. 10.5.14

Underground Installations

(1) Underground installations of Class 2 circuits shall be installed in accordance with Clause 8.3.3. (2) Direct buried Class 2 circuits shall maintain a minimum horizontal separation of 300.0mm from other underground systems except when installed in accordance with (3) below. (3) Direct buriedClass 2 circuits may be placed at random separation in a common trench with power circuits which are for the sole purpose o~ supplying power to the Class 2 circuits provided that the Class 2 circuit is in a metal sheathed cable, with sheath bonded to earth, the power circuit operates at 750.0V or less, and all conductors are insulated for the maximum voltage of any conductor in the trench.


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SECTION

11

INSTALLATION OF ELECTRICAL EQUIPMENT

11.1

SCOPE

(1) This Section applies to the installation of the following electric equipment:

a) b) c) d) e) f)

11.2

Heating and cooking. Submersible pump. Motors and associated circuits. Air conditioning. Refrigerating. Storage batteries.



(a)

NFPA 70/NEC:1986

(b)

C22.l: 1990

11.3

National Fire Protection Association/American National Electrical Code, 1987 Edition. Canadian Electrical Code, Part 1, Safety Standard for Electrical Installations, Sixteenth Edition.

GENERAL

11.3.1 Fusible Equipment (1) Fusible equipment shall employ low-melting-point fuses when connected to conductors whose ampacity is based on Annex B of Section 4, unless equipment using other types of fuses is marked as being suitable for such use.

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SECTION 11: INSTALLATION OF ELECTRICAL EQUIPMENT

11.3.2 Connection to Identified Terminals or Leads (1) Wherever a device having an identified terminal or leads is connected in a circuit having identified conductors, the identified conductors shall be connected to the identified terminal or lead.

11.3.3 Equipment over Combustible Surfaces (1) Where there is a combustible surface directly under stationary or fixed electrical equipment, that surface shall btl covered with a steel plate at least 1.6mm thick and which shall extend at least IS0.0mm beyond the equipment on all sides, if:

a) the equipment is marked to require such protection; or

b) the equipment is open on the bottom.

11.3.4 Installation of Ventilated Enclosures (1) Ventilated enclosures shall be installed in such a manner that ventilation is not restricted.

11.3.5 Outdoor Installations (1) Outdoor installations of apparatus, unless-housed in suitable enclosures, shall be surrounded by suitable fences.

(2) Outdoor equipment shall be bonded to earth in an acceptable manner.

·11.4

ELECTRIC HEATING AND COOKING APPLIANCES

11.4.1 Location of Non-Portable Appliances (1) Non-portable electric heating and cooking appliances shall be installed so that the danger of igniting nearby combustible materials is reduced to a minimum.

11.4.2 Rating of Portable Appliances (2) The input to portable electric heating and cooking appliance for use on nominal 230.0V branch circuits protected by overcurrent devices rated or set at not more than I6.0A shall not. exceed IS00.0W at 230.0V.


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11.4.3 Appliance Exceeding 1500.0W (1) Every electric heating and cooking appliance rated at more than 1500.0W shall be supplied from a branch circuit used solely for one appliance except that more than one appliance.may be connected to a single-branch circuit provided that following is used: a) A multiple-throw, manually-operated device that will permit only one such appliance to be energized at one time; or b) An automatic device that will limit the total load to a value that will not cause operation of the overcurrent device protecting the branch circuit. (2) Every electric heating and cooking appliance rated at more than 1500.0W shall be controlled by an indicating switch which may be in the circuit or on the appliance except that: a) if the rating of the appliance does not exceed 32.0A, an attachment plug and socket outlet may be used instead of a switch; and b) if the appliance has more than one individual heating element each controlled by a switch, no main switch need be provided. Note:

For the purposed of this Clause, two or more separate built-in cooking units, together with their overcurrent devices, ars: considered as one appliance.

11.5 HEATING EQUIPMENT (1) All electric power for heating and associated equipment operating in connection therewith shall be obtained from a single-branch circuit which shall be used for no other purpose. (2) A suitable disconnecting means shall be provided for the feeder or branch circuit.

11.6 SUBMERSmLE PUMPS (1) Power supply conductors or cables run from well-head to the pump (deep well submersible pump) shall be: a) rubber (thermoset) insulated cable, thermoplastic-insulated cable, single conductors or , twisted assemblies of this types; or b) extra-hard usage type, or the equivalent portable cable.

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(2) The area around the submersible pump installed in lakes, rivers and streams shall be protected from access by the public by fencing, cribbing or isolation and so marked.

11.7

MOTORS AND ASSOCIATED CIRCUITS

11.7.1

Wirin~

Methods and Conductors

11.7.1.1 Stationary motors (1) The wiring method for stationary motors shall be in accordance with the applicable requirements of Section 8.

11.7.1.2 Portable Motors (1) Connections to portable motots shall be permitted with flexible cord which shall have a serviceability not less than that of extra-hard usage cord unless the motor forms part of a motor-operated device.

11.7.1.3 Motor supply conductor insulation, temperature rating, and ampacity (1) Supply conductors to a motor connection box shall have an insulation temperature ratings equivalent to or greater than those provided in Table 11.1 unless the motor is marked otherwise and their ampacity based on a 7SoC conductor insulation rating when 90°C wire is used as circuit conductors to the motor.

(2) Where Table 11.1 requires insulation temperature ratings in excess of 7SoC, the motor supply conductors shall not be less than 1.2m long and shall terminate in a location not less than 600.0mm from any part of the motor except that, for motors rated IOO.Ohp or larger, their terminations shall be not less than 1.2m from any part of the motor. (3) For ambients higher than 30°C, the supply conductor insulation rating shall be increased at least by the difference between the ambient and 30°C.

11.7.1.4

Conductors to individual motors

(1) The conductors of a branch circuit supplying a continuous-duty motor shall have an ampacity not less than 125% of the full-load current rating of the motor.


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(2) The conductors of a branch circuit supplying a non-continuous-duty motor shall have an ampacity not less than the current value obtained by multiplying the full-load current rating of the motor by the applicable percentage given in Table 11.2 for the duty involved. (3) Notwithstanding the Provisions of (1) above, conductor ampacities shall be permitted to be selected from Table 11.5 using the full-load current rating for a continuous duty motor. (4) Tap conductors supplying individual motors from a single set of branch circuit overcurrent device supplying two or more motors shall have an ampacity of at least equal to that of the branch circuit conductors except that where the tap conductors do not exceed 7.5m in length, they shall be permitted to be sized in accordance with (1) or (2) above provided the ampacity so determined is not less than Y3 of the ampacity of the branch circuit conductors.

11.7.1.-5

Conductors - two or more motors

(1) Conductors supplying a group of two or more motors shall have an ampacity equal to or exceeding:

(a)

(b) (c)

125% of the full-load current rating of the motor having the largest full load current rating plus the full load current ratings of all the other motors in the group where all motors' in the group are continuous-duty motors; the total of the calculated currents determined in accordance with (a) above for each motor where all motors in the group are non-continuous-duty motors; or the total of the following where the group consists of two or more motors of both continuous and non-continuous-duty types: 125% of the current of the continuous-duty motor having the largest full load current rating; (ii) the full-load current ratings of all other continuous duty motors; and (iii) the calculated current determined in accordance with (2) below for the non continuous duty motors. i)

(2) Where the circuitry is so interlocked as to prevent all motors of the group from running at the same time, the size of the conductors feeding the group shall be permitted to be determined for the motor, or group of motors operating at the same time, having the largest rating selected as determined in (I) above.

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(3) Demand factors shall be permitted to be applied if the character of the motor loading justifies reduction of the: ampacity of the conductor to less than the ampacity specified in (1) above provided that: (a) the conductors have sufficient ampacity for the maximum demand load; and (b) the rating ur selling uf the overcurrent devices protecting them is in accordance with 11.7.2.3(4) below.

11.7.1.6

Feeder conductors

(1) Where a feeder supplies both motor loads and other loads, the ampacity of the conductors shall be calculated in accordance with 11.7.1.4 and 11.7.1.5 plus the requirements of the other loads. (2) The ampacity of a tap from a feeder to a single set of overcurrent devices protecting a motor branch circuit shall not be less than that of the feeder, except that the ampacity of the tap shall be permitted to be calculated in accordance with 11.7.1.4 and 11.7.1.5 if the tap: (a) (b)

11.7.1.7

does not exceed 3.0m in length and is enclosed in metal; or does not exceed 7.5m in .length, has an ampacity not less than Y3 that of the feeder and is suitably protected from mechanical damage.

Secondary conductors

(1) Conductors connecting the secondaries of wound rotor motors to their controllers shall have ampacities not less than: (a) (b)

125% of the rated full load secondary current for continuous-duty motors; or the percentage of rated full load specified in Table 11.2 for non-continuous-duty motors.

(2) Ampacities of conductors connecting secondary resistors-to their controllers shall not be less than that determined, by applying the appropriate percentage in Table 11.3 to the maximum current which the devices are required to carry.


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11.7.2

Overcurrent Protection

11.7.2.1 Branch Circuit overcurrent protection (l) Each unearthed conductor of a motor branch circuit shall be protected by an overcurrent device complying with the following:

(a) A branch circuit supplying a single motor shall be protected, except as permitted by (c) below, by using an overcurrent device of rating not to exceed the values in Table 11.4 / using the rated full load current of the motor; (b) notwithstanding (a) above, Table 11.5 shall be permitted to be used to select the size of overcurrent devices required for a motor where the full load current rating of the motor is shown in the Table; (c) instantaneous trip (magnetic only) circuit interrupters shall be permitted where applied in accordance with 11.7.2.5; (d) where the overcurrent devices as determined in (a) above will not permit the motor to start, the rating or setting of the overcurrent device shall be permitted to be increased as follows: (i) A non-timedelay fuse: _. not in excess of 400% of the motor full load current for fuses rated up to 600.0A; or - not in excess of 300% of the motor full load current for fuses rated 601 to 6000 A; or (ii) A timedelay fuse to a maximum of 225% of the motor full load current; and (e)

11.7.2.2

for a branch circuit supplying two or more motors, the rating or setting of the overcurrent device shall not exceed the maximum value permitted by 1L7.2.4.

Overcurrent protection marked on eqidpment

(1) Where the characteristics and rating or setting of a branch circuit protective device are / specified in the marking of motor control equipment, they shall not be exceeded, notwithstanding any greater rating or ~etting permitted by 11.7.2.1. /

260

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11.7.2.3 Feeder overcurrent protection (1) For a feeder supplying motor branch circuits only, the rating or setting of the feeder overcurrent device shall not exceed a maximum value calculated by determining the maximum rating or setting of the overcurrent device permitted by 11.7.2.1 for that motor which is permitted the highest rated overcurrent devices of any motor supplied by the feeder, and adding thereto the sum of the full load current ratings of all other motors which will be in operation at the same time. (2) (i) Where a feeder supplies a group of motors, two or more of which are required to start simultaneously, and the feeder overcurrent devices as set in accordance with (1) above are not sufficient to allow the motors to start, the rating or setting of the feeder overcurrent devices shall be permitted to be increased as necessary to a maximum. (ii) Notwithstanding the Provisions of (i) above, the permitted increase shall not exceed the rating permitted for a single motor having a full load current rating not less than the sum of the full load current ratings of the greatest number of motors which start simultaneously, provided this value does not exceed 300% of the ampacity of the feeder conductors. (3) Where a feeder supplies one or more motor branch circuits together with other loads, the required overcurrent protection shall be determined by calculating the overcurrent protection required for the motor circuits and adding thereto the requirements of the other loads supplied by the feeder. (4) Where a demand factor has been applied as permitted in 11.7.1.5(3b), the rating or setting of the overcurrent devices(s) protecting a feeder shall not exceed the ampacity of the feeder, except as permitted by applicable Clauses of Section 8.

11.7.2.4 Grtluping of motors on a single branch circuit (1) Two or more motors shall be permitted to be grouped under the protection of a single set of branch circuit overcurrent devices having a rating or setting calculated in accordance with 11.7.2.3(1) provided that the protection conforms to one of the following: (a) The ratings or settings of the overcurrent devices do not exceed 16.0A; or (b) Protection is provided for the control equipment of the motors by having the branch circuit overcurrent devices rated or set at:


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ELECTRICAL iNSTALLATION OF BUILDINGS

values not in excess of those marked on the control equipment for the lowest rated motor of the group, as suitable for the protection of that control equipment; or (ii) in the absence of such markings, values not in excess of 400% of the full-load current of the lowest rated motor. (i)

(0) The motors are used on a machine tool or woodworking machine; and

(i)

the control equipment is arranged so that all contacts which open the motor's primary circuits are in enclosures, either forming part of the machine base or for separate mounting, having a wall thickness not less than 1.69mm for steel, . 2.40mm for malleable cast iron, or 6.30mm for other cast metal, having hinged doors with substantial catches, and having no openings to the floor or the foundation on which the machine rests; and (ii)the ratings or settings of the overcurrent devices do not exceed 200.0A at 230.0V or less, or 100.OA at voltages from ,231.0V to 750.0V. (d) All the motors are operated by a single controller.

11.7.2.5

Instantaneaus-sripcireuit interrupters

(l) Instantaneous trip circuit interrupters, when used for branch circuit protection, shall be:

(a) part of a combination motor starter or controller that also provides overload protection; and (b) rated or adjusted, for an a.c. motor, to trip at not more than 1300% ofthe motor full load current or at not more than 215% of the motor locked rotor current, where given, except that ratings or settings for trip current need not be less than 16.0A; or (c) rated or adjusted, for a d.c. motor rated at 50.0hp or less, to trip at not more than 250% of the motor full load current, or for a d.c. motor rated at more than 50.0hp, to trip at not more than 200% of the motor full-load current. 11.7.3

Overload and Overheating Protection

11.7.3.1 Overloadprotection requited (1) The branch circuit conductors and control equipment of each motor shall have overload

protection, except as permitted by II. 7.3.5

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SECTIOt\1 11: INSTALLATION OF ELECTRICAL EQUIPMENT

11.7.3.2 Types of overload protection (1) Overload devices shall be either:

(a) a separate overload device which is responsive to motor current and which shall be permitted to combine the function of overload and overcurrent protection if it is capable of protecting the circuit and motor under both overload and short circuit conditions, (b) a protective device, integral with the motor and responsive to motor current and temperature, provided such device will protect the circuit conductors and control equipment as well as the motor. (2) Fuses used as separate overload protection of motors shall be timedelay fuses.

11.7.3.3 Number and location of overload devices (1) The number and location of current-responsive devices shall be:

(a) if fuses are used, one it! each unearthed conductor; or (b) as specified in Table 9.1, Section 9, if devices other than fuses are used. (2) Except by special permission, where current-responsive devices are used for the overload protection of 3-phase motors, such devices shall comprise of three current-responsive elements which shall be: (a) connected directly in the motor circuit conductors as required by (1) above; or (b) fed by two or three current transformers so connected that all 3-phases will be protected,

11.7.3.4 Rating or trip selection of overload devices (1) Overload devices responsive to motor current shall be rated or selected to trip at not more than the following: (a) 125% of the full-load current rating of a motor having a marked service factor of 1.15 or greater; or (b) 115% of the full-load current rating of a motor which does not have a marked service factor or where the marked service factor is less than 1.15.


EBCS-10 1995

263


.(2) Notwithstanding the Provisions of (1) above, Table 11.5 shall be applicable to determine the type of the overcurrent device required for motors having a service factor of 1.15 or greater where the full-load current rating of the motor is listed in the Table. (3) Where a motor overload device is so connected that it does not carry the total/current designated on the motor nameplate, such as for wye-delta starting, the percentage/of motor nameplate current applying to the selection or setting of tli'e overload device shall be clearly marked on the motor starter or shown In the motor starter manufacturers overload selection table.

11.7.3.5

Overload protection not required

(1) Overload protection shall not be required for motors complying with any of the following: (a) A manually started motor rated at l.Ohp or less that is continuously attended while in operation, which is on a branch circuit having overcurrent protection rated or set at not more than 16.0A or on an individual branch circuit having overcurrent protection as required by Table 11.5 if it may be readily determined from the starting location that the motor is running. (b) A motor constructed so that it cannot be overloaded. (c) A motor whose operating requirements are such that it is impracticable to obtain proper overload protection. (d) An automatically startable motor having a rating of l.Ohp or less forming part of an assembly equipped with other safety controls that protect the motor from damage due to stalled-rotor current and on which a nameplate, so located as to be visible after installation, indicates that such protection features are provided.

11.7.3.6

Shunting of overload protection during starting

(1) Overload protection shall be permitted to be shunted or cutout of a circuit during the starting period, provided that the device by which the protection is shunted or cutout cannot be left in the starting position and that the overcurrerit device is in the motor circuit during the starting period.

11.7.3.7 Automatic restarting after overload (l) Where automatic restarting of a motor after a shut down on overload could cause injury to

persons, the overload or overheating devices protecting the motor shall be so arranged that automatic restarting cannot occur.

264

EBCS-10 1995


-----------~---

~-------~. ~


11.7.3.8

Overheating protection required

(1) Each motor shall be provided with means of overheating protection except as permitted by 11.7.3.10.

11.7.3.9

Types 0/ overheating protection

(1) Overheating protection, where required by 11.7.3.8, shall be provided by devices integral with the motor and responsive to both motor current and temperature or to motor temperature only, and shall be arranged to cut off power to the motor or, by spacial permission, to activate a warning signal when the temperature exceeds the safe limit for the motor.

(2) Motors with inherent overheating protection acceptable under (1) above shall be marked to indicate that they are thermally protected or impedance protected.

11.7.3.10 Overheating protection not required (1) Overheating protection shall not be required:

(a) where the motor circuit requires no overload protection under 11.7.3.5; or - (b) where overload protective devices required by 11.7.3.2 adequately protect the motor against overheating due to excess current and the motor is in a location where: (i) ambient temperatures are not more than l O'C higher than those at the location of the overload devices; and (ii) dust or other conditions will not interfere with the normal dissipation of heat from the motor.

11.7.4 Undervoltage Protection 11.7.4.1

Undervolatge protection required/or motors

(1) Motors shall be disconnected from the source of supply in case of low voltage by one of the following means unless it is evident that no hazard will be incurred through lack of such

disconnection:


EBCS-10 1995

265

ELEC"fAICAL INSTALLATION OF BUILDINGS

(a) A motor control device shall provide low-voltage protection when automatic restarting is liable to create a hazard. (b) The motor control device shall provide low-voltage release when it is necessary or desirable that a motor stops on failure or reduction of voltage and automatically restart on return of voltage.

11.7.4.2

Undervoltage protection on feeders or branch circuits

(l) The protection specified in II. 704.1 shall be permitted to be applied to a feeder or branch

circuit supplying a group of motors, in which case the individual motors need not. be so protected, provided the means for manually resetting a low-voltage protective device shall be within sight of all machines supplied by a feeder or branch circuit and so located that the operator can visually assure himself that safe re-energization of the feeder or branch circuit is possible.

11.7.5

Control

11.7.5.1 Control required (1) Except as permitted by (3) below, each motor shall be provided with a motor starter or controller for starting and stopping it and having a rating, in horsepower, not less than the rating of the motor it serves.

(2) A motor controller need not open the circuit in all unearthed conductors to a motor unless it also serves as a disconnecting means. (3) The motor starter or controller specified in (1) above shall not be required for motors applied as follows: (a) A singlephase portable motor rated at lhhpor less, connected by means of a socket outlet and attachment plug rated not in excess of 16.0A, 230.0V. (b) A motor controlled by a manually operated general-use switch having an ampere rating not less than 125% of the full load current rating of the motor. (c) A two-wire potable a.c. or d.c. motor having a rating not in excess of lhhp, 230.0V controlled by a horsepower rated singlepole motor switch.

. 266

EBCS-10 1995


I


11.7.5.2

Control location

(1) A motor controlled manually, either directly or by a remote control of a motor starter, shall

have the means of operation by the controller so located:

(a) that safe operation of the motor and the machinery driven by it is assured, or the motor and the machinery shall be guarded or enclosed so as to prevent accidents due to contact of persons with live or moving parts; or (b) where compliance with (a) above is not practicable because of the type, size or location .---' of the motor or machinery and its parts, devices shall be provided at each point where the danger of accidents exists whereby the machine or parts of the machine may be stopped in an emergency.

11.7.5.3

Starters having different starting and running positions

(1) Manual motor starters having different starting and running positions shall be constructed so that they cannot remain in the starting position.

(2) Magnetic motor starters having different starting and running positions shall be constructed so that they cannot remain in the starting position under normal operating conditions. 11.7.5.4

Earthed control circuit

(1) When power for a co~trol circuit for a.motor controller is obtained conductively from an earthed system, the control circuit shall be so arranged that an accidental earth in the wiring from the controller to any remote or signal device will not: (a) start the motor; or (b) prevent the stopping of the motor by the normal operation of any control or safety device in the control circuit.

11.7.6 Disconnecting Means (1) Except as permitted by (2) and (3) below, separate disconnecting means shall be provided

for: (a) each motor branch circuit, (b) each motor starter or controller, and (c) each motor.


EBCS-10 1995

267

.>

--------_._-~-~

---

.- ......

-- ----_ ...

_----------~---_ ..


(2) A single disconnecting means shall be permitted to serve more than one of the functions described in (1) above. (3) A single disconnecting means shall be permitted to serve two or more motors and their associated starting and control equipment grouped on a single branch circuit. (4) Disconnecting means or the means for operating themshall readily be accessible.

11.8

AIR CONDITIONING AND REFRIGERATING EQUIPMENT

11.8.1 General (1) The provisions of Section 11.7 for overload, overheating and control of motors shall apply to electric motor driving air conditioning and refrigerating equipment.

11.8.2 Branch Circuit (l) A room air conditioner shall be considered as a single motor unit in determining its branch circuit requirements when all the following conditions are met:

(a) It is cord-and-attachment plug-connected. (b) Its rating is not more than 40.0A and 230.0V single phase. (c) Total rated-load current is shown on the room air-conditioner nameplate rather than individual motor currents. (d) The rating of the branch-circuit, short-circuit and earth-fault protective device does not exceed the ampacity of the branch-circuit conductors or the rating of the socket outlet, whichever is smaller. (2) The total marked rating of a cord-and-attachment plug-connected room air conditioner shall not exceed 80% of the rating of a branch circuit where no other loads are supplied. (3) The total marked rating ofa cord-and-attachment plug-connected room air conditioner shall not exceed 50% of the rating of a branch circuit where lighting units or other appliances are also supplied.

268

EBCS-10 1995



11.8.3 Disconnecting Means (1) An attachment plug and socket outlet are permitted to serve as disconnecting means for a single-phase room air conditioner rated i30.0Y or less if: (a) the manual controls on the room air conditioner are readily accessible and located within 2.0m of the floor; or (b) an approved, manually operable switch is installed in a readily accessible location within sight from the room air conditioner.

11.8.4 Supply Cords (1) Where a flexible cord is used to supply a room air conditioner, the length of such cord shall not exceed 2.0m for a nominal 230.0Y rating.

11.9

STORAGE BATTERIES

11.9.1 Location of Storage Batteries (1) Batteries with exposed live parts shall be kept in a room or an enclosure accessible only to authorized personnel.

11.9.2 Ventilation of Battery Rooms or Areas (1) Storage, battery rooms or areas shall be adequately ventilated. (2) Storage batteries shall not be subjected to ambient temperatures greater than 45°C or less than the freezing point of the electrolyte.

11.9.3 Battery Vents (l) Vented cells shall be equipped with flame arresters.

(2) Sealed cells shall be equipped with pressure-release vents.

11.9.4 Battery Installation (l) Battery trays, racks and other surfaces on which batteries are mounted shall be:

a) level,

b) protected against corrosion from the battery electrolyte,


EBCS-10 1995

269


c) covered with an insulating material having a dialectic strength of at least 1500.0V, d) of sufficient strength to carry the weight of the battery, and e) designed to withstand vibration and sway, where appropriate. (2) Battery cells shall be spaced a minimum of 1O.Omm apart. (3) Battery cells having conductive containers shall be installed on non-conductive surfaces. (4) Sealed cells and multi-compartment sealed batteries having conductive containers shall have an insulating support if a voltage is present between the container and earth. (5) Cells and multi-compartment vented stage batteries, with covers sealed to containers of non conductive, heat resistant material, shall not require additional insulating support. (6) Batteries having a nominal voltage greater than 230.0V and with cells in rubber or composition containers shall be sectionalized into groups of 230.0V or less. 11.9.5 Wiring (1) The installation of wiring and equipment in a battery room shall be in accordance with the requirements of a dry location.

(2) The wiring between cells and batteries and between the batteries and other electrical equipment shall be: a) b) c) d)

bare conductors.which shall not be tapped; open wiring; a jacket flexible cord; mineral-insulated cable provided it is adequately protected against corrosion where it may be in direct contact with acid or acid spray; or e) aluminium-sheathed cable provided that it has a suitable corrosion-resistant protection, where necessary. (3) Where wiring is installed in rigid conduit or electrical metallic tubing: a) the conduit or tubing shall be of corrosion-resistant material suitably protected from corrosion; b) the end of the raceway shall be tightly sealed with sealing compound, rubber tape, or other acceptable material, to resist the entrance of electrolyte by spray or creeping;

270

EBCS-10 1995



c) the conductor shall issue from the raceway through a substantial glazed insulating bushing; d) at least 300.0mm of the conductor shall be free from the raceway where connected to a cell terminal; and e) the raceway exit shall be at least 300.0mm above the highest cell terminal to reduce the electrolyte creepage or spillage entering the raceway. Table 11.1 Minimum temperature rating for the insulation of motor supply conductor [0C] (Based on ambient temperature of 30°C) Insulation class rating. Motor enclosure

A

B

F

H

All except totally enclosed nonventilated

75

75

90

110

Totally enclosed non-ventilated

75

90

11.0

110

Table 11.2 Conductor sizes for motors for different service requirements Percentage of nameplate current rating of motor

s-rnlnute rating

15 minute rating

30-and 60 minute rating

Contlnu ous rating

110

120

150

-

85

85

90

140

Periodic duty Rolls, ore-and coal-handling machines, etc.

85

90

95

140

Varyng duty

110

120

150

200

Classification of service

Short-time dUty Operating valves, raising or lowering. rolls, etc. Intermittent dUty Freight and passenger elevators, tools heads, pumps, drawbridges, turntables, etc.


EBCS-10 1995

271


TABLE 11.3 Conductor sizes in the secondaryCircuits of motors

Duty cycles

Carrying capacity of conductors In percent of full-load secondary circuit

5 sec on 75 sec off 10 sec on 70 sec off 15 sec on 75 sec off 15 sec on 45 sec off 15 sec on 30 sec of 15 sec on 15 sec off Continuous Duty

35 45 55 65 75 90 110

Resistor duty classification

Light staring duty Heavy starting duty Extra heavy starting duty Light intermittent duty Medium intermittent duty Heavy intermittent duty Continuous dUty

Table 11.4 Rating or setting of overcurrent devices for the protection of motor branch circuits (Except as permitted in Table 11.5 where 16-A overcurrent protection for motor branch circuit conductors exceeds the values specified in here)

Per cent of full-load current

Tlmedela y fuses

Non tlmedelay

Maximum setting tlme limit type circuit breaker

175

300

250

175

300

250

175 175 150

250 200 150

200 200 150

150

150

150

. Maximum fuse rating

Type of Motor

.

Alternating Current Single-phase all types' Squirrel-cage and synchronous: Full-voltage, resistor and reactor Staring Auto-Transformer starting: Not more than 30.0A More than 30.0A Wound rotor Direct Current

The ratings of fuses for the protection of motor branch circuits as given in Table 11.5 are based upon fuse ratings appearing in the Table above, which also specifies the maximum settings of circuit breakers for the protection of motor branch circuits. (il) Synchronous motors of the low-torque, low-speed type (usually 4S0.0rpm, or lower) such as are used to drive reciprocating compressors, pumps, etc., and which start up unloaded, do not require a fuse rating or circuit breaker setting in excess of 200% of full-load current. (iii) For the use of instantaneous trip (magnetic only) circuit interrupters in motor branch circuits, see 11.7.2.5.

Note;

(i)

272

EBCS-10 1995

!


~

Table 11.5 Sizes of conductors, fuse ratings, and circuit breaker settings for motor overload protection and motor circuit overcurrent protection (This Table is based on Table 11.4 and a room temperature of 30°C).

Overcurrent protection maximum allowable rating of fuses and Maximum allowable setting of circuit breakers of the time-limited Type for motor circuits [A]

Overload protection for running protection of motor [A] Full~load

current rating of motor [A]

Minimum allowable ampacity of conductor

Maximum rating of Type 0 Fuses

Maximum setting of overload devices

1 2 3 4 5

1.25 2.50 3.75 5.00· 6.25

1.125 2.25 3.5 4.5 5.6

1.125 2.25 3.75 5.00 6.25

6 7 8

7 8

10

7.50 8.75 10.00 11.25 12.50

7.50 8.75 10.00 11.25 12.50

11 12 13 14 15

13.75 15.00 16.25 17.50 18.75

9

9

I

10 12

Single phase, all types and squirrel cage and synchronous (Full voltage, Resistor and Reactor Starting)

!

Squirrel cage and Synchronous (Autotransformer and Star-Delta Starting)

I . I

d.c. or wound rotor a.c.

Non-time delay Fuses

Timedela y"D" Fuses

Circuit breaker

Non-time .delay fuses

Timedela y"D" fuses

Circuit Breaker

Non-time delay fuses

Time delay "0" fuses

Circuit breaker

15 15 15 15 15

15 15 15 15 15

15 15 15 15 15

15 15 15 ·15 15

15 15 15 15 15

15 15 15 15 15

15 15 15 15 1'5

15 15 15 15 15

15 15 15 15 15

20 25 25 30 30

15 15 15 20 20

15 15 20 20 20

15 15 20 25 25

15 15 15 20 20

15 15 15 15 20

15 15 15 15 15

15 15 15 15 15

15 15 15 15 15

30 40 40 45 45

20 25 25 25 30

30 30 30 30 30

30 30 35 35 40

20 25 25 25 30

20 20 30 30 30

29 20 20 25 25

20 20 20 25 25

15 15 20 20 20

, 1

~

~.

12 15 15 17.5 ~F·5

13.75 15.00 16.25 17.50 18.75

I

~ Table 11.5 Sizes of conductors, fuse ratings, and circuit breaker settings for motor overload protection and motor circuit overcurrent protection (conte'd) (This Table is based on Table 11.4 and a room temperature of 30°C).

Overload protection for running protection of motor [A] Full.load current rating of motor [A]

Minimum allowable ampacltyof conductor



Overcurrent protection maximum allowable rating of fuses and Maximum allowable setting of circuit breakers of the tlme-llrnlted Type for motor circuits [A] Single phase, all types and squirrel cage and synchronous (Full voltage, Resistor and Reactor Starting)




Timedela y"O" Fuses

Circuit breaker


Timedela y "0" fuses

Circuit Breaker


Time delay "0" fuses

Circuit breaker

16 17 18 19 20

20.00 21.25 22.50 23.75 25.00

17.5 20 20 20 25

20.00 21.25 22.50 23.75 25.00

50 60 60 60 60

30 30 35 35 35

40 40 40 40 50

40 45 45 50 50

30 30 35 35 35

30 30 30 40 40

25 30 30 30 30

25 30 30 30 30

20 30 30 30 30

22 24 26 28 30

27.5 30.0 32.5 35.0 37.5

25 30 30 35 35

27.5 30.0 32.5 35.0 37.5

60 80 80 90 90

40 45 50 50 60

50 . 60 60 70 70

60 60 70 70 70

40 45 50 50 60

40 40 50 50 60

35 40 40 45 45

35 40 40 45 45

30 30 40 40 40

32 34 36 38 40

40.0 42.5 45.0 47.5 50.0

40 40 45 45 50

40.0 42.5 45.0 47.5 50.0

100 110 110 125 125

60 60 70 70 70

70 70 100 100 100

70 70 80 80 80

60 60 70 70 70

60 60 70 70 70

50 60 60 60 60

50 60 60 60 60

40 50 50 50 60

Table 11.5 Sizes of cond.uCtors, fuse ratings,

and Circuit breaker settings fOI" Iilotor overload protection and motor circuit overcurrent protection

(conte'd)

(This Table is based on Tabie 11.4 lind a room temperature of 30°C). "'-

",

- .

..

..

~.

---"

Overload proteCtion for runnin~ protection of motor [Ai Minimum allowable ampacltyof conductor

f'ull-ioad current rating of motor [AJ

Maximum ratirig of type b Fuses

Maximurn setting of averldad devices ..


Tirnedela yiiDil Fuses

Squirrel cage arid Synchronous (Autotransformer and Star-Delta Starting)

Circuit breaker ..

Non-time delay . .. fuses

Tlmedela y"D" fuses

Circuit Breaker

d.c, or wound rotor a.c,


Time delay liD" fuses

Circuit breaker

50 50 50 60 60

52;5 55.0 57;5 60.0 62.5

125 125 150 150 150

80 80 90 90 90

100 100 100 10Q 125

90 90 100 100 1'00

80 90 90 90 90

70 100 100 100 100

70 70 70 80

eo

70 70 70 80 80

60 60 70 70

52 56 58 60

65.0 67.5 70.0 72.5 75.6

60 60 70 70 70

65.0 61.5 70.0 12.5 75.0

175 175 175 175

2dO

100 100 100 110 110

125 125 125 125 150

11o 110 126 126 125

100 100 100 110 110

100 100 100 100 100

80 90 90 90 90

80 90 90 90 90

70 70 70 100 100

62 64 66 68 70

71.5 80.0 82.5 85.0 87.5

70 10 80 80 80

80.0 82.5 85.0 87.5

200 200 20b 225 225

11o 125 125 125 125

150 150 150 150 175

125 150 150 150 160

110 125 125 125 125

125 125 125 125 125

100 100 100 110 110

100 100 100 110 110

100 100 100 100 100

72 14

90.0 92.5 95.0 91.5 100,cl

80 90 90 90 90

225 225 250 250 25Cl

150 150 150 150 150

115 175 175 175 200

150 150 175 115 115

150 150 150 150 150

125 125 150 150 150

110 125 125 125 125

110 125 125 125 125

100 100 100 100 100

78 80 .~..

Singie phase; all types and squirrel cage arid synchronous (Full voltage, Resistor and Reactor St8:rting)

525 55.0 57.5 60.0 62.5

76 ;;.,;j Vi

O"ercurrerrt protection maximum alloWable rating of fuses and lIIIaxlinum allowable setting of circuit breakers of the time-limited type for motor circuits tAJ .. ..

42 44 46 48 50

54

t-:.!

.

..,

',"-

>.

>

77.5

96.0

92.5 95.0 97.5 100.0

..

~

."'

60

Table 11.5 Sizes of conductors, fuse ratings, and circuit breaker settings for motor overload protection and motor circuit overcurrent protection (conte'd) (This Table is based on Table 11.4 and a room temperature of 30°C). I

Overload protection for running protection of motor [A]

Overcurrent protection maximum allowable rating of fuses and Maximum allowable setting of circuit breakers of the time-limited Type for motor circuits [A]

i

- -

Full-load current rating of motor [A]

Minimum allowable ampacltyof conductor



86

88

90

102.5 105.0 107.5 110.0 112.5

90

100

100

100

100

92

94

96

98

100

115.0 117.5 120.0 122.5 125.0

105

110

115

120

125

130

135

140

145

150

82

84

Single phase. all types and squirrel cage and synchronous (FUll voltage, Resistor and Reactor Starting)


t--~


--,----


limedela y"O" Fuses

102.5 105.0 107.5 110.0 112.5

250 250 300 300 300

110

110

110

110

110

115.0 117.5 120.0 122.5 125.0

131.5 137.5 144.0 150.0 156.5

125

125

125

125

150

162.5 169.0 175.0 181.5 187.5

150

150

150

175

175

Circuit breaker


limedela y"O" fuses

Circuit Breaker


lime delay "0" fuses

Circuit breaker

150 150 175 175 175

200 200 200 200 225

175 175 175 200 200

150 150 175 175 175

150 150 150 175 175

125 150 150 150 150

125 150 150 150 150

125 125 125 125 125

300 300 300 300 300

175 175 175 175 175

225 225 225 225 225

200 200 200 200 200

175 175 175 175 175

175 175 175 175 175

150 150 150 150 150

150 150 150 150 150

125 125 125 125 150

131.5 137.5 144.0 150.0 156.5

350 350 350 400 400

200 200 225 225 225

250 250 250 250 250

225 225 250 250 250

200 200 225 225 225

200 200 225 225 250

175 175 175 200 200

175 175 175 200 200

150 150 150 175 175

162.5 169.0 175.0 181.5 187.5

400 450 450 450 450

250 250 250 300 300

300 300 350 350 350

300 300 300 300 300

250 250 250 300 300

250 250 250 250 300

20Q 225 225 225 225

200 225 225 225 225

175 200 200 200 225

~

, ,

Table 11.5 Sizes of conductors, fuse ratings, and circuit breaker settings for motor overload protection and motor circuit overcurrent protection (conte' d) (Ibis Table is based on Table 11.4 and a room temperature of 30"C).

Overcurrent protection maximum allowable rallng of fuses and Maximum allowable setting of circuit breakers of the time-limited Type for motor circuits [A]

Overload protection for running protection of motor [A] FUll-load current rating of motor [A]

Minimum allowable ampaclty of conductor

Fuses

Maximum' setting of overload devices

Maximum rating of Type D

~

-...J

Single phase, all types and squirrel cage and synchronous (Full voltage, Resistor and Reactor Starting)



Non-time delay F!Jses

limedela y liD" Fuses

Circuit breaker


limedela y''O" fuses

Circuit Breaker


lime delay "0" fuses

Circuit breaker

155 160 165 170 175

194 200 206 213 219

175 175 200 200 200

194 200 206 213 219

500 500 500 500 600

300 300 300 300 350

350 400 400 400 400

350 350 350 350 350

300 300 300 300 350

300 300 300 300 350

250 250 250 300 300

250 250 250 300 300

225 ' 225 225 250 250

180 185 190 195 200

225 231 238 244 250

200 200 225 225 225

225 231 238 244 250

600 600 600 600 600

350 350 350 350 350

400 400 400 400 500

400 400 400 400 400

350 350 350 350 350

350 350 350 350 400

300 300 300 300 300

300 300 300 300 300

250 ' 250 250 250 300

210 220 230 240 250

263 275 288 300 313

250 250 250 250 300

263 275 288 300 313

-

400 400 450 450 450

500 500 500 600 600

450 450 500 500 500

400 400 450 450 450

400 400 400 400 500

350 350 350 400 400

350 350 350 400 400

300 300 300 350 350

-

,

Table U.5 Sizes of conductors, fuse ratings, and circuit breaker settings for motor overload protection and motor circuit overcurrent protection (conte'd) (This Table is based on Table 11.4 and a room temperature of 30pe).

Overload protection for r'unnlrtg protection of motor [A] FuJl~load

current rating of motdr [A]

Minimum allowable ampaclty of. col1ductdr ".

Maximum rating of fypeD Fuses

260 270 280' 290 300

325 338 350 363 315-.

300 300 300 350 350

320 340 360 380 400

400 425 450 475 500

420 440 460 480 500


32$ 338'

Overcurtent protectlort maximum allowable rating of f~ and Maximum allowable setting of circuit breakers of the time-limited Type for motor circuits [A] . Single phase, all types and squirrel cage and synchronous (Full voltage, Resistor and Reactor Starting)

Squirrel eage and Synchronous (Autotransformer and Star-Delta starting)


Tlmedela

-

500 500 500

600

600

600

600

600

-

y"O. Fuses

Non-time

Tmedela

de18y

y"O.

fuses

fuses

600,

600

600

600

500 500 500 600 600

Circuit breaker

350 363 375

· ·

60Q

600

600

350 400 400 450· 450

400 425 450 475

·

.-

-

-

52.5

500

525

550

500 500 500 600

550

515

600 625

500

575 600

625

-

-

-

~

.

-

-

-

.

· ·-

-

~

-

-

.

-

·

-

· -

-

·

--

500

500 500 500 600

--

.

-

Circuit Breaker

-' ~

d.c. or wound rotor a.c,

Non~time

delay fUSes

Time delay. "0" fuses

400 450 450 450 450

400 450 450 450 450

500 600

500

-

-

600 600 600

-

-

-

-

-

..

-

.

-

Cireuit breaker

350 ~oo

'400 400 400 400 500

600 600 600

500 500

600

600

-

-

. .

-

-

-

SECfION

12

HAZARDOUS LOCATIONS

12.1

SCOPE

(1) This Section applies to hazardous locations in which electrical equipment and wiring are subject to the conditions classified as follows: (a) (b) (c)

12.2

Class I locations in which flammable gases or vapouls are or may be present in the air in quantities sufficient to produce explosive or ignitible mixtures; Class II location which are hazardous because of-the presence of combustible or electrically conductive dusts; and Class III locations which are hazardous because of the presence of easily ignitible fibres or flyings, but in which such fibres or flyings are not likely to be in suspension in the air in quantities sufficient to produce ignitible mixtures.

NORMATIVE REFERENCE

(1) The following reference contains provisions which, through reference in this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings. (a)

12.3

C22.1:1990


CLASSIFICATION

12.3.1 Division of Class I Locations (1) Class I locations shall be divided into two divisions as follows: (a) Division 1, comprising Class I locations in which:


. EBCS-10 1995

279


.i)

hazardous concentration of flammable gases or vapours may exist continuously, intermittently, or periodically under normal operating conditions; ii) hazardous concentrations of flammable gases or vapours may exist frequently because of repair or maintenance operation or because of leakage; or iii) equipment is operated or processes are carried on, of such a nature that breakdown or faulty operation thereof could result in the release of hazardous concentrations of flammable gases or vapours and simultaneous failure of electrical equipment.

(b)

Division 2, comprising Class I locations in which: (i) flammable volatile liquids, flammable gases or vapours are handled, processed, or used, but in which the liquids, gases, or vapours are normally confined within closed containers or closed systems from which they can escape only as a result of accidental rapture or breakdown of the containers or systems or the abnormal operation of the equipment by which the liquids or gases are handled, processed, or used; or (ii) hazardous concentration of gasses or vapours are normally prevented by . positive mechanical ventilation, but which may become hazardous as the result of failure or abnormal operation of the ventilating equipment; or (iii) the location is adjacent to a Class I, Division 1 location, from which a hazardous concentration of gasses or vapours could be communicated, unless such communication is prevented by adequate positive-pressure' ventilation from a source of clean air, and effective safeguards against ventilation failure are provided.

12.3.2 Division of Class II Locations

(L) Class II locations shall be divided into two divisions as follows: a) Division 1 comprising Class II locations in which: i) combustible dust is or may be ih suspension in air continuously, intermittently, or periodically under normal oeperating conditions in quantities sufficient to produce explosive or ignitible mixtures; ii) jhe normal or abnormal operation or the failure of equipment or apparatus might cause explosive or ignitible mixtures to be produced in, or in dangerous proximity to, 'electrical equipment or apparatus; or

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SECTION 12: HAZARDOUS LOCATIONS

iii dusts having the property of conducting electricity may be present. b) Division 2, comprising Class.II locations in which combustible dusts are not normally in suspension in air or likely to be thrown into suspension by the normal or abnormal operation or the failure of equipment or apparatus in quantities sufficient to produce explosive or ignitible mixtures, but in which: . i) deposits or accumulations of dust may be sufficient to interfere with the safe dissipation of heat from electrical equipment or apparatus; or ii) deposits or accumulations of dust on, in or near electrical equipment may be ignited by arcs, sparks, or burning material from the electrical·equipment. 12.3.3 Division of Class III Locations (1) Class III locations shall be divided into two divisions as follows: a) Division 1, comprising Class III locations in which readily ignitible fibres or materials producing combustible flyings are handled, manufactured, or used .... b) .Division 2, comprising Class III locations in which readily ignitible fibres other than those in process of manufacture are stored or handled. 12.4

GENERAL

REQUI~MENTS

12.4.1 Electrical Equipment (1) Where electrical equipment is required by this Section to be approved for the class of location, it shall also be approved for the specific gas, vapour, or dust that will be present. (2) Such approval in (1) may be indicated by one or more of the following atmospheric group designations which have been established for the purpose of testing and approval: a) Group A, comprising atmospheres containing acetylene; b) Group B, comprising atmospheres containing butadiene, ethylene oxide, hydrogen (or gasses or vapours equivalJnt in hazard to hydrogen, such as manufactured gas), or propylene oxide;

ETHIOPIAN· BUILDINiG CODE SIfANDARD

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c) Group C, comprising atmospheres containing acetaldehyde, cyclopropane, diethyl . ether, ethylene, or unsymmetrical dimenthyl hydrazine (UDMH), or other gases or vapours of equivalent hazard; d) Group D, comprising atmospheres containing acetone, acrylonitrile, alcohol, ammonia, benzine, benzol, ethylene dichloride, gasoline, hexane, isoprene, lacquer solvent vapours, naphtha,natural gas, propane, propylene styrene, vinyl acetate, vinyl chloride, xylenes, or other gases or vapours or equivalent hazard; e) Group E, comprising atmospheres containing metal dust, including aluminum, magnesium, and their commercial alloys, and other metals of similarly hazardous character istics; t) Group F, comprising atmospheres containing carbon black, coal or coke dust; g) Group G, comprising atmospheres contaiiring flour, starch or grain dust, and other dusts of similarly hazardous characteristics. 12.4.2 Marking (1) Electrical. equipment approved for use in hazardous locations shall be marked to indicate the class and for Classes I andll locations the group, or the specific gas, vapour or dust for which the equipment has been approved.

(2) Electrical equipment approved for use in Class I hazardous locations may be marked with: a) the maximum external temperature, or b) one of the following temperature codes in Table 12.1 to indicate .the maximum external temperature; Table 12.1 Temperature codes to lndlcsbe the maximum external temperature Temperature code

r.mperature Gode

Max. external temperature [0C]

T1

450

T3A

180

T2

300

T3B

165

T2A

280

T3C

160

T2B

260

T4

135

T2C

230

T4A

120

T2D

215

T5

100

T3

200

T6

85

282 I

Max. external temperature [0C]

EBCS-10 1995


-,

SECTION 12: HAZARDOUS LOCATIONS 'j

(3) If no maximum external temperature marking is shown on Class I equipment approved for the class and group, the equipment, if of the heat-producing type (which excludes junction boxes, conduit fittings, etc), shall be considered as having the following maximum external temperature: Group Group Group Group

A B C D

-

2800C 2800C 1600C 215°C

(4) Equipment approved for Class I, Division 2 only shall be so marked. (5) Electrical equipment approved for operation at ambient temperatures exceeding 400C shall, in addition to the marking specified in 12.4.2 be marked with,the maximum ambient temperature for which the equipment is approved, and the maximum external temperature of the equipment as referred to in (2) and (3) above. 12.4.3 Non-Essential Electrical Equipment (1) No electrical equipment shall be used in a hazardous location unless it is essential to the processes being carried on therein. . (2) Service equipment, panelboards, switchboards, and similar electrical equipment, shall, 'where practicable, be located in rooms or sections of the, building in which hazardous conditions do not exist. 12.4.4 Equipment Rooms (1) Where walls, partitions, floors or ceilings are used to form hazard-free rooms or sections, they shall be: a) of substantial construction; b) built of or lined with noncombustIble material; and c) such as to ensure that the rooms or section will remain free from hazards. '


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(2) Where a non-hazardous location within abuilding communicates with a Class I, Division 2 location, a Class IT location, or a Class ill location, the locations shall be separated by close-fittings, self-closing,. approved fire doors. 12.4.5 Cable Trays (1) Cable trays shall not be used to support cables in hazardous locations except where: .

a) the type of cable is approved in Clauses of this Section for use in the particular hazardous location; and b) there can be no hazardous accumulation of combustible process dust or fibre in or upon the cable; the cable tray or the supports.

u.s

CLASS I LOCATIONS

12.5.1

Installations in Class I, Divisiop 1 Locations

12.5.1.1

Transformers and capacitors

(1) Transformers and electrical capacitors which contain a combustible liquid that will burn . shall be installed in electrical equipment vaults in accordance with applicable Clauses of Section 11. 12.5.1.2

Meiers, instmments and relays

(1) Where practicable, meters, instruments and relays, including kilowatt-hour meters, instrument transformers and resistors, rectifiers and thermionic tubes shall be located outside the hazardous locations. (2) Where it is not practicable to install meters, instruments, and relays outside Class I, Division 1 locations, they shall be approved for Class I locations: 12.5.1.3 Switches,'motor controllers, circuit breakers and fuses (1' Switches, motor controllers, circuit breakers and fuses, including push buttons, relays, and similar devices shall be provided with enclosures; the enclosure in each case, together with the enclosed apparatus, shall be approved as a complete assembly for use in Class I locations. ,

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12.5.1.4 Motors and generators

(1) Motors, generators and other rotating electrical machines shall be approved for Class I locations. 12.5.1.5

Wiring methods'

(1) The wiring method shall be 'thre~ded rigid-metal conduit or cables approved for hazardous locations with associated cable glands approved for the particular hazardous location. (2) All boxes, fittings, and joints shall be threaded for conrtection to conduit or cable glands, and shall be explosion-proof with boxes and fittings approved for Class I locations. (3) Threaded joints shall have at least five full threads fully engaged and running threads shall not be> used. (4) Cables shall be installed and supported in a manner to avoid tensile stress atJ.b~. .cable glands. .,' ,··
.'

.'

(5) Where it is necessary to use flexible connections at motor terminals and similar places, flexible fittings of the. explosion-proof type and approved for the location shall be used. (6) Seals shall be provided in conduit or cable systems to prevent the passage of gases, vapours, or flames from one portion of the electrical installation to another through the' system. 12.5.1.6 Lighting fixtures

(1) Fixtures for fixed and portable lighting shall be approved as complete assemblies for Class I locations and shall be clearly marked to indicate the maximumwattage of lamps for which they are approved. (2) Boxes, box assemblies or fittings used for the support of lighting fixtures shall be approved for the purpose and for Class I locations.


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ELECTRICAL INSTALLATION OF BUfLDINGS

12.5.2

Installations in Class I, Division 2 Locations

12.5.2.1

Wiring methods

(1) The wiring method shall be: a) threaded metal conduit; or b) cables approved for hazardous locations with associated cable glands approved for the particular hazardous location. (2) Cable shall be installed and supported in a manner to avoid tensile stress at the cable glands. (3) Where it is necessary to use flexible connection at motor terminals and similar places, flexible metal conduit may be used. (4) Boxes, fittings and joints need not be-explosion-proof (5) Seals shall be provided in conduit or cable systems to prevent the passage of gases, vapours, or flames through the system from one portion of the electrical installation to another.

12.5.2.2 Motors and generators (1) Motors, generators, and other rotating electrical machines, in which are incorporated arcing or spark-producing components or integral resistance devices, shall be approved for Class I, Division 2 locations unless the arcing or spark-producing components or· integral resistance devices are provided with enclosures approved for Class I locations. (2) Motors, generators, and other rotating electrical machines which do not incorporate arcing or spark producing components or integral resistance devices may be of the open or non-explosion-proof type. 12.5~2.3

Lighting fixtures

(1) Fixed lighting shall be: a) protected from physical damage by acceptable guards or by location;

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b) approved as complete assemblies for Class I, Division 2 locations and shall be clearly marked to indicate the maximum wattage, voltage, and specific type designations of the lamps for which they are approved. (2) Pendent fixtures shall be suspended by threaded rigid conduit systems or by other approved means. " (3) Starting and control equipment for electric-discharge lighting equipment shall be provided with enclosures approved for the location. 12.6

CLASS II LOCATIONS

12.6.1

Installations in Class II, Division 1 Locations

12.6.1.1


(l) Transformers and electrical capacitors which contain a combustible liquid shall be installed in electrical equipment vaults in accordance with applicable Clauses of Section 11. 12.6.1.2 Switches, controUers, circuit breakersandfuses

(1) Switches, motor controllers, circuit breakers and fuses, including push buttons, relays, and similar devices, shall be provided with a dust-tight enclosure approved for Class IT locations. 12.6.13

Motors and generators

(1) Motors, generators and other rotating electrical machines shall be approved for Class IT locations. 12:6.1.4

Wiring methods

(1) The wiring method shall be threaded. rigid metal conduit or cables approved for hazardous locations with associated cable glands approved for the particular hazardous location. (2) Boxes, fittings and joints shall be threaded for connection to conduit or cable glands and boxes and fittings shall be approved for Class II locations.


EBCS-10 1995 . 287

~

i I


(3) Cables shall be installed and supported in a manner to avoid tensile stress at the cable glands. (4) Where flexible connections are necessary, they shall be provided by: a) flexible connection fittings approved for the location; b) liquid-tight flexible metal conduit with fittings approved for the location; or c) extra-hard-usage flexible cord and provided with cable glands approved for the location. (5) Where flexible connections are subject to oil or corrosive conditions, the insulation of the conductors shall be of type approved for the condition or shall be protected by means ofa suitable sheath. (6) Where a raceway provides communication between enclosures one of which is required to be dust-tight and the other not, the entrance of dust into the dust enclosure through the raceway shall be prevented by: a) a permanent and effective seal; b) a horizontal section not less than 3.0m long in the raceway; or c) a vertical section of raceway not less than 105m long and extending downward with ~ the dust-tight enclosure.

12.6.1.5

Lighting.fixtures

(1) Fixtures for fixed and portable lighting shall be approved as complete assemblies for Class II locations and shall be clearly marked to indicate the maximum wattage of lamps for which they are approved. (2) Pendent fixtures shall be suspended by threaded rigid conduit stems or chains with approved fittings or by other approved means which shall not includ~ a flexible cord as the supporting medium, and threaded joints shall be provided with-set screws or other effective means to prevent loosening. (3) Boxes, box assemblies or fittings used for the support of lighting fixtures shall be approved for the purpose. . ~

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12.6.2

Installation in Class II, Division 2 Locations

12.6.2.1


(1) Transformers and electrical capacitors which contain a combustible liquid shall be installed in electrical equipment vaults in accordance with applicable clauses of Sections 11. 12.6.2.2

Switches, controUers, circuit "breakers and fuses

(1) In locations where dust from magnesium, aluminum, aluminum bronze powders, or other metals of similar hazardous characteristics may be present, switches, motor controllers, circuit breakers, and fuses shall have dust-tight enclosures approved for such locations. 12.6.2.3 ,Motors and generators

(1) Motors, generators and other rotating electrical machinery shall be: a) approved for Class II, or Class II Division 2 locations; b) ordinary, totally enclosed pipe-ventilated or totally enclosed fan-cooled and subject to the following:

i) be equipped with integral overheating protection in accordance with 11.7.3.8 ii) if drain holes or other openings are provided they shall be closed with threaded plugs. 12.6.2.4

Wiring methods

(1) The wiring method shall be: a) threaded metal conduit; or b) cables approved for hazardous locations with associated cable glands approved for the particular hazardous location. (2) Cables shall be installed and supported in a manner to avoid tensile stress at the cable glands.


EBCS-10 1995 , 289


12.6.2.5 Lighting fixtures . (1) Fixed lighting.shall: a) be protected from physical damage by acceptable guards or by location; b) provide enclosures for lamp and lampholders which shall be designed to minimize the deposit of dust .on lamps and to prevent the escape of sparks, burning material, or hot metal; c) be clearly marked to indicate the maximum wattage of lamps for which they may be used without exceeding a maximum exposed surface temperature of 165°C under normal conditions or use. (2) Pendent fixtures shall be suspended by threaded rigid conduit stems or chains with approved fittings, or by other approved means, which shall not include flexible cord as the supporting medium.

(3) Boxes, box assemblies or fittings used for the support of lighting fixtures shall be. approved for that purpose, (4) Starting and control equipment for mercury-vapom:.and fluorescent lamps shallconform to the requirment of 12.6.2.2.

12.7

CLASS III LOCATIONS

12.7.1 .Installations in Class III, Division 1 Locations

12.7.1.1

~ransformers

and capacitors

(1) Transformers and capacitors shall conform to the requirement ·of12.6;2.1

12.7.1.2 Switches, cntrotlen, circuit ,beakers anilfuses (1) Switches, motor controllers, circuit breakers and fuses, including push buttons, relaYs. and similar devices, shallbe p!ovided with tight enclosures designed toannimfzeentrance of fibres and flyings, and which shall: a) be equipped with telescoping or closefittin,g covers; or with other 'effective means to prevent escape of sparks or burning material; and

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b) have no openings, such as holes for attachment screws, through which, after installation, sparks or burning material might escape, or through which exterior accumulations of fibres or flyings or adjacent combustible material might be ignited. 12.7.1.3

Motors and generators

(1) Except as provided in (2) below, motors, generators and other rotating electricalmachinery shall be: a) totally enclosed non-ventilated, b) totally enclosed pipe-ventilated, c) totally enclosed fan-cooled. (2) Where only moderate accumulations of lint and flyings are likely to collect on or in the vicinity of a rotating electrical machine and the machine is readily accessible for routine cleaning and maintenance, there may be installed in the location: . a) standard open-type machines without sliding contacts, centrifugal, or other types of switching mechanism, including motor overload devices; b) standard open-type machines which have contacts, switching mechanisms, or resistance devices enclosed within tight housings without ventilating or other openings; or c) self-cleaning textile motors of the squirrel-cage type. (3) Motors, generators and other rotating electrical machinery of the partially enclosed or splash-proof type shall not be installed in Class III locations. 12.7.1.4 Wiring methods (1) The wiring method shall be threaded rigid metal conduit or cables approved for hazardous locations with associated cable glands approved. for the particular hazardous location. (2) Boxes and fittings in which taps, joints or terminal connections are made shall: a) be provided with telescoping or close fitting covers, or other effective means to prevent the escape of sparks or burning material; and


EBCS-10 1995291


b) have no openings, such as holes for attachment screws, through which after installation, sparks or burning material might escape, or through which adjacent combustible material might be ignited. (3) Cables shall be installed and supported in a manner to avoid tensile stress at the cable glands. (4) Where it is necessary to use flexible connections, the provisions of 12.6.1.4(4) and 12.6.1.4(5) shall apply. 12.7.1.5

Lighting fixtures

(1) Fixed lighting shall: a) provide enclosures, for lamps and lampholders, which shall be designedto minimize entrance of fibres and flying objects and to prevent the escape of sparks, burning material, or hot metal; b) be clearly marked to indicate the maximum wattage .lamp which may be used without exceeding a maximum exposed surface temperature of 165°C under normal conditions of use. (2) Lighting fixtures which may ~e exposed to physical damage shall be protected by a suitable guard. (3) Pendent fixtures shall comply with the requirments of 12.6.2.5(2). (4) Boxes, box assemblies or fittings used for the support of lighting fixtures shall be approved for that purpose. 12.7.1.6

Storage-battery charging equipment

(1) Storage battery charging equipment shall be located in a separate room built or lined with substantial noncombustible materials so constructed as to adequately exclude flyings or lint, and shall be well ventilated.

292

EBCS-10 1995



12.7.2

Installations in Class III, Division 2 Locations

12.7.2.1

Transformers and CIlpacitors

(1) Transformers and capacitors shall conform to the requirement of 12.6.2.1.

12.7.2.2

Wiring method

(1) The wiring method in Class IiI, Division 2 locations shall conform to 12.7.1.4 except . that in sections, compartments or areas used solely for storage and containing no machinery, open wiring on insulators, in accordance with applicable Clauses of Section 8, may be used, provided that, where conductors are installed elsewhere other than in roof spaces and remote from physical damage, they shall be protected by running board not less than 19.0mm thick or other acceptable means. . 12.7.2~

Switches, co1llTOllers, cireuit breaker» andfuses

(1) Switches, motor controllers, circuit breakers, and fuses shall conform to the requirement of 12.7.1:2.

12.7.2.4 Motorsand generators . (1) Motors, generators, and other rotating electrical machinery shall be: a) totally enclosed non-ventilated;

b) totally enclosed pipe-ventilated; .or

c) totally enclosed fan-cooled.

(2) Motors, generators or other rotating electrical machinery of the partially enclosed or splashproof type shall not be ittstalled in Class ill locations.


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293

SECTION

13

FlAMMABLE UQUID DISPENSING AND

SERVICE STATIONS, GARAGES,

BULK STORAGE PIANTS, FINISIHNG

PROCESSES AND AIRCRAFT HANGARS·

U.t

SCOPE

(1) This Section applies to electrical apparatus and wiring installed in the following facilities; a) Gasoline dispensing and service stations;and other locations where gasoline or other similar volatile flammable liquids are dispensed or transferred to fuel tanks of self propelled vehicles. b) Commercial garages, repair houses and storage where service and repair operations of vehicles of the type described in (a) above are carried out and in which more than three such vehicles are, or may be, stored at anyone time. e) Residential storage garages in which not more than three vehicles of the type described in (a) above are, or may, be, stored, but which will not normally be used for service or repair operations. d} Bulk st-orage plants where gasoline or other similar volatile flammable liquids are stored in tanks having an aggregate capacity of one-ear-load or more, and' from which such products are distributed (usually by tank truck)• .e), FInishing processes where paints, lacquers or other flammable finishes are re~lIar1y or frequently applied by spraying, dipping, brushing or by other means, and where volatile flammable solvents or thinners are used or where readily ignitible deposits or residues from such paints, lacquers, or finishes may occur.

294

EBCS;.10 t995

ETHIOPIAN BUILDING CODE STAN;oARD

\

SECTION 13: FLAMMABLE UQUID DISPENSING AND OTHERFACILlT(ES

Q Aircraft hangars used for storage or servicing of aircraft in which gas()line jet fuels, or other volatile flammable liquids, or flammable gases, are used; but' shall 'not . include those locations used exclusively for aircrafts that have never contained such liquids or gases, or which have been drained and properly purged.

13.2

NORMATIVE REFERENCES'

(1) The following references containprovisions which, through reference in this text, constitute

provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings. (a) C22.1:1990

(b)

13.3

NEC Handbook:1981

Canadian Electrical Code, Part 1 Safety Standard for Electrical Installations, Sixteenth Edition. National Electrical Code Handbook, Based on the 1981 (NEC), Seventeenth Edition.

GASOLINE DISPENSING AND SERVICE STATIONS

13.3.1 Hazardous Areas (1) The space within a ~penser enclosureupto 1.2m vertically above its base including the space below'the dispenser which may contain electrical wiring and equipment, shall be considered to be Class I, Divisionl location. (2) The space within a nozzle boot of a dispenser shall be considered to be a Class I Division 1 location. . (3) The space within 450.0mm horizontally from the Division 1 location within the dispenser enclosure as specified in (1) above shall be considered to be a. Class I,' Division 1 location. (4) In an outside location, any ar~' beyond the Class I, DivisionI area within .6.0m horizontally from the exterior enclosure of' any dispenser shall be considered a Class I, Division 2 location, which will extend to a level 4~O.Onup above driveway or ground level.


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(5) In an outside location, any area beyond the Class I, Division 1 location and within 3.0m horizontally from any tank fillpipe shall be considered a Class I, Division 2 'location which shall extend upward to a level 450.0mm above driveway or ground level. (6) Electricalwiring and equipment, any portion of which is below the surface of areas defined as Class I, Division 1 or Division 2 in (1), (3), (4) or (5) above shall be considered to be within Class I, Division 1 location which shall extend at least to the point of emergence above grade. (7) Areas within the vicinity of tank ventpipes shall be classified as follows: a) The spherical volume within a 900.0mm radius from point of discharge of any tank ventpipe shall be considered a Class I, Division 1 location and the volume between the 900.0mm to 15m radius from point of discharge of a vent shall be considered a Class I, Division 2 location. .b) For any vent that does not discharge upward, the cylindrical volume below both the Division 1 and Division 2 locations extending to the ground shall be considered as Class I, Division 2 location. c) The hazardous area shall not be.considered to extend beyond an unpierced wall. (8) Areas within lubrication rooms shall be classified as follows: a) The area within any pit or space below grade or floor level shall be considered a Class I, Division 1 location unless the pit or space is beyond the hazardous areas specified in (4), (5), (6), (7) above in which case the pit or space shall be considered a Class I Division 2 location. b) Thearea within the entire lubrication room up to 50.0mm above the floor or grade, whichever is' the higher, and the area within 900.0mm measured in any direction from the dispensing point of a hand-operated unit dispensing volatile flammable liquids shall be considered a Class I, Division 2 location. 13.3.2 Wiring and Equipment within Hazardous Areas (1) Electrical wiring and equipment within the hazardous areas defined in Clause 13.3.1 shall conform to the requirements of Section 12. I

II

296

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ETHIOPIAN BUILDING :CODE STANDARD

/

SECTION 13: FLAMMABLE LIQUID DISPENSING AND OTHER FACILITIES

(2) Where dispensers are supplied byrigid metal conduit, flexible fittings of the explosion proof type approved for the location shall be-used between the conduit and the junction box of the dispenser in addition to any sealing fittings and unions that may be required pursuant to the provisions of Section 12. (3) Each circuit leading to or through a dispensing pump shall be provided with a switching means which will disconnect simultaneously from the source of supply all unearthed conductors of the circuit. (4) All non-current-carrying metal parts of dispensing pumps, metal raceways and other electrical equipment shall be bonded to earth in accordance with Section 7 of this Code. 13.3.3 Wiring and Equipment above Hazardous Areas (1) Wiring and equipment above hazardous areas - shall meet the requirements and provisions of Clauses 13.4.3 and 13.4.4 of this Section. 13.4

COMMERCIAL GARAGES, REPAIRS AND STORAGE

13.4.1 Hazardous Areas (1) For each floor at or above grade, the entire area up to a level 50.0mm above the floor shall be considered to be a Class I, Division 2 Iocation. (2) For each floor below grade, the entire area up to a level 50.0mm above the bottom of outside doors or other openings which are at or above grade level shall be considered to be a Class I, Division 2 location except -that, where adequate mechanical ventilation is provided, the hazardous location shall extend up to a level of only 50.0mm above each such floor. (3) Any pit or depression below floor level shall be considered to be a Class I, Division 2 location which shall extend up to the floor level. (4) Adjacent areas in which hazardous vapours are not likely to be released such as stockrooms, switchboard rooms, and other similar locations having floors elevated at least 50.0mm above the adjacent garage floor, or separated therefrom by tight curbs or partitions at least 50.0mm high, shall not be classified as hazardous.


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13.4.2 Wiring and Equipment in Hazardous Areas

(1) Within hazardous areas as defined in Clause 13.4.1, wiring and equipment shall conform to the requirements of applicable Clauses of Section 12. 13.4.3 Wiring above Hazardous Areas

(1) All fixed wiring above hazardous areas shall be carried out in accordance with the provisions of Section 8 and suitable for the type of building and occupancy. (2) For pendants, flexible cord of the hard-usage type shall be employed. (3) For connection of portable lamps, portable motors, or other portable utilization equipment, flexible cord of the hard-usage type shall be used. 13.4.4 Equipment above Hazardous Areas

(1) Fixed equipment which is less than 3.6m above the floor level and which may produce arcs, sparks, or particles of hot metal such as cutouts, switches, charging panels, generators, motors or other equipment (excluding socket outlets, lamps and lampholders) having make and-break or sliding contacts, shall be of the .totally enclosed type or so constructed as to prevent escape of sparks or hot metal particles. (2) Lamps and lampholders for fixed lighting and that are located over lanes through which vehicles are commonly driven or which may otherwise be exposed to physical damage shall be located not less than 3.6m above floor level unless of totally enclosed type or so constructed as to prevent escape of sparks or hot metal particles. 13.5

RESIDENTIAL STORAGE GARAGES

13.5.1 Non-Hazardous Location

(1) Where the lowest floor is at or above adjacent grade or driveway level, and where there is at least one outside door at or below floor level, the garage area shall not be classified as a hazardous location.

298

EBCS-10 1995


SECTION 13: FLAMMABLE LIQUID' DISPENSING AND OTHER FACILITIES

13.5.2 Hazardous Location (1) Where the lowest floor is below adjacent grade or driveway level, the following shall apply: a) The entire area of the garage or of any enclosed space which includes the garage shall be classified as a Class I, Division 2 location and will extend up to a level 50.0mm above the garage floor. b) Adjacent areas in which hazardous vapours or gases are not likely to be released, and having floors elevated at least. 50.0mm above the garage floor, or separated therefrom by tight curbs or partitions at least 50.0mm high shall not be classified as hazardous.

13.5.3 Wiring (1) Wiring above the hazardous locations shall conform to the provisions of Section 8. (2) Wiring in the hazardous location shall conform to the provisions of Section 12.

13.6

BULK STORAGE PLANTS

13.6.1 Hazardous Areas (1) Areas containing pumps, bleeders, withdrawal fittings, metres and si:milar devices wliich are located in pipelines handling flammable liquids under pressure shall be classified and comply with the following: a) Ventilated indoor areas shall be considered as Class I, Division 2 locations within a 105m distance extending in all directions from the exterior surface of such devices as well as 7.5m horizontally from any surface of these devices and extending upwards to 900.0mm above floor or grade level, provided that: design of the ventilation systems takes into account the relatively high relative density of the vapours; ii) where openings are used in outside walls, they are of adequate size and located at floor level unobstructed except by louvres or coarse screens; and

i)


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299

ELECTRICAL INSTALLATION/OF BUILDINGS

iii) where natural ventilation is inadequate, mechanical ventilation is provided. b) Indoor areas not ventilated in accordance with (a) above shall be considered Class I, Division 1 locations within a 15m distance extending in all directions from the exterior surface of such devices as well as 7.5m horizontally from any surface of the device and extending upward 900.0mm above floor or grade level. c) Outdoor area shall be considered as Class I,_Division 2 locations within a 900.0mm distance extending in all directions from the exterior surface of such devices as well as up to 450.0mm above grade levelwithin 3.0m horizontally from any surface of the devices. (2) Areas where flammable liquids are transferred shall be classified as follows: a) In outdoor areas or where positive and reliable mechanical ventilation is provided in indoor areas in which flammable liquids are transferred to individual containers, such areas shall be considered a Class I, Division 1 locations within 900.0mm of the vent or fill opening extending in all directions and a Class I, Division 2 location within the area extending between a 900.0mm and 15m radius from the vent or fill opening extending in all directions, and including the area within a horizontal radius of 3.0m from the vent or fill opening and extending to a height of 450.0mm above floor or grade levels. b) Where positive and reliable mechanical ventilation is not provided in indoor areas in which flammable liquids are transferred to individual containers, such areas shall be considered to be a Class I, Division 1 location. (3) Areas in outside locations where loading and unloading of tank vehicles and tank cars take place shall be classified as follows: a) The area extending 900.0mm in all'directions from the dome (when loading through an open dome) or from the vent (when loading through a closed dome with atmospheric venting) shall be considered a Class I, Division 1 location. b) The area extending "between a 900.0mm and a 15m radius from the dome (when loading through an open dome) or from. the vent (when loading through a closed dome with atmospheric venting) shall be considered a Class I, Division 2 location.

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EBCS-10 1995



c) The area extending within 900.0mm in all directions from a fixed connection used in bottom loading or unloading, loading through a closed dome with atmospheric venting, or loading through a closed dome with a vapour recovery system shall be considered a Class I, Division 2 location except that, in the. case of bottom loading . or unloading, this classification shall also be applied to the area within a 3.0m radius from point of connection and extending 450.0mm above grade. (4) Area within the vicinity of above-ground tanks shall be classified as follows: a) The area above the roof and within the shell of a floating-roof type tank shall be. considered a Class I, Division 1 location. b) For all type of above-ground tanks: i) the area within 3.0m from the shell ends, and roof of other than a floating-roof shall be considered a Class I, division 2 location; and ii) where dikes are provided, the area inside the dike and extending upwards to the top of the dike shall be considered to be a Class I, Division 2 location. c) The area within 15m of vent opening and extending in all directions shall be considered a Class I, Division 1 location. d) The area between 15m and 3.0m of a vent opening and extending in all directions shall be considered a Class I, Division 2 location. (5) Pits and depressions shall be classified as follows: a) Any pit or depression, any part of which lies within a Division 1 or Division 2 location, unless provided-with positive and reliable mechanical ventilation, shall be considered a,Class I, Division 1 location. b) Any such areas as in (a) above, when provided with positive and reliable mechanical ventilation, shall be considered a Class I, Division 2 location. c) Any pit or depression not within a Division 1 or Division 2 location as defined herein, but which contains piping, valves, or fittings shall be considered a Class I, Division 2 location.: (6) Garages in which tank vehicles are stored or-repaired shall be considered to be a Class I, Division 2 location up to 450.0mm above floor or grade level.


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ELECTRICAL INSTALLATION OF6UILDINGS

(7) Buildings such as office buildings, boiler rooms, etc which are outside the limits of hazardous areas as defined herein and which are not used for handling or storing volatile flammable liquids or containers for such liquids shall not be considered to be hazardous locations.

13.6.2 Wiring and Equipment in Hazardous Areas (1) All electrical wiring and equipment in hazardous areas defined in Clause 13.6.1 shall conform to the requirements of Section 12. 13.6.3 Wiring and Equipment above Hazardous Areas (1) Wiring installed above a hazardous location shall. conform. to the requirements of Section 8 and be suitable for the type of buildings and occupancy. (2) Fixed equipment which may produce arcs, sparks or particles of hot metal, such as lamps and lampholders, cutouts, switches, socket outlets, motors or other equipment having make-and-break or sliding contacts, shall be of the totally enclosed type or so constructed as to prevent the escape of sparks or hot metal particles. (3) Portable lamps or utilization equipment and the flexible cords supplying them shall conform to the requirements of Section 12 for the class of location above which they are connected or used. (4) All non-current-carrying metal parts of equipment and raceways shall be bonded to earth in accordance with Part I of Section 7 of this Code.· 13.7

FINISlDNG PROCESSES

13.7.1 Hazardous Locations (1) The following areas shall be considered to be Class I, Division 1 locations: a) The interiors of spray booths and their exhaust ducts. b) All space within 6.0m horizontally in any direction, and extending to a height of . 900.0mm above the goods to be painted, from spraying operations that are .more extensive than touch-up spraying and not conducted within the spray booth..

302

EBCS-10 1995



c) All space within 6.0m horizontally in any direction from dip tanks and their drain

boards, such space extending to a height of 900.0mm above the dip tank and drain

board.

d) All other spaces where hazardous concentrations of flammable vapours are likely to

occur.'

(2) For spraying operations within an open face spray booth, the extent of the Class I,

Division 2 hazardous location shall be not less than the following:

a) Where the ventilation system is interlocked with the spraying equipment so as to

make the spraying equipment inoperable when the ventilation system is ~ot in

operation, the space shall extend at least 1.5m from the open face of the spray

booth.

b) Where the ventilation system is not interlocked with the spraying equipment so as

to make the spraying equipment inoperable when the ventilation system is not in

operation, the space shall extend at least 3.0m from the open face or front of the

.spray·booth. (3) All space within the room, but beyond the limits for Class I, Division 1 location as classified in (1) above.for extensive open-spraying, for dip tanks and drain boards and for

other hazardous operations, shall be considered to be Class I, Division 2 location. (4) Adjacent areas which area cut off from the defined hazardous area by tight partitions without communicating openings, and wi~hin which hazardous vapours are not likely to be released, shall be classified as non-hazardous. (5) Drying and baking areas provided with positive mechanical ventilation to prevent

formation of flammable concentration of vapours and provided with effective interlocks to

.de-energize all electrical equipment, not approved for Class I locations, in case the ventilating equipment is inoperative, may be classified as non-hazardous. (6) Notwithstanding the requirements of (Ib) above,where adequate mechanicalventilation with effective interlocks is provided at floor level: a} the space within'900.0mmhorizontally in any direction from the goods to be painted

and such space extending to a height of 900.0mm above the goods to be painted

shall be considered a Class I, Division 1 location; and


EBCS-10 1995

303

I

•


b) all space between a 900.0mm and 15m distance above the goods to be painted and' all space within 6.0m horizontally in any direction beyond the limits for Class I, . Division 1 location shall be considered a Class I, Division 2 location. (7) Notwithstanding the requirements of (2) above where a baffle of sheet metal of not less than l.25mm is installed vertically above the front face of an open-face spray booth to a height of 900.0mm or to the ceiling, whichever is lower and extending back on the side edges for a distance of 15m, the space behind this baffle shall be considered to be a non hazardous location. 13.7.2 Wiring and Equipment in Hazardous Areas (1) All electrical wiring and equipment within the hazardous areas as defined in Clause 13.7.1 shall conform to the requirements of Section 12. (2) Unless specifically approved for both readily ignitable deposits and flammable vapour location, no electrical equipment shall be installed or used where it may be subject to a hazardous accumulation of readily ignitable deposits or residue. (3) Illumination of readily ignitable area through panels of glass or other trnsparent 011 translucent materials is permissible only where: a) fixed lighting units are used as the source of illumination;

b) the panel is noncombustible and effectively isolates the hazardous area from the

area in which the lighting unit is located; c) the lighting unit is acceptable for its specific location; d) the panel is of a material or is so protected that breakage will be unlikely; 'e) the arrangement is such that normal accumulation of hazardous residue on the surface of the panel will not be raised to a dangerous temperature by radiation conduction from the source of illumination.

or

(4) Portable electric lamps or other utilization equipment shall: a) not be used within a hazardous area during operation of the finishing process; b) be of a type specifically approved for Class I locations when used during cleaning or repairing operations. (5) Notwithstanding the requirements of (2) above:

304

'

EBCS-10 1995



a) totally enclosed and gasketted lighting may be used on the ceiling of a spray room where adequate and positive mechanical ventilation is provided; and b) infra-red paint-drying units may be utilized in a spray room if the controls are interlocked with those of the spraying equipment such that both operations cannot .be performed simultaneously; and if portable, the paint and the drying unit shall not be brought into the spray room until the spraying operations have ceased. 13.7.3 Wiring and Equipment above Hazardous Areas

(1) All fixed wiring above hazardous area shall conform to the provisions of Section 8. (2) Equipment which may produce arcs, sparks, or particles of hot metal, such as lamps and lampholders for fixed lighting, cutouts, switches, receptacles, motors Of other equipment having make-and-break or sliding contacts, where installed above a hazardous area or above an area where freshly finished goods are handled, shall be of the totally enclosed type or so constructed as to prevent the escape of sparks or hot metal particles. (3) All metal raceways and all non-current-carrying metal portions of fixed or portable equipment, regardless of voltage, shall be bonded to earth in accordance with Part I Of Section 7 of this Code: 13.8

AIRCRAFT HANGARS

13.8.1 Hazardous Areas

(1) Any pit or depression below the level of the hangar floor shall be considered to be a Class I, Division 1 location which shall extend up to the floor level. (2) The entire area of the hangar; including any adjacent and communication areas not suitably cut off from the hangar shall be considered to be Class I, Division 2 location up to a level 450.0mm above the floor. (3) The area within 15m horizontally from aircraft power plants, aircraft fuel tanks, or aircraft structures containing fuel shall be considered to be a Class I, Division 2 location which shall extend upward from the floor to a level 105m above the upper surface of wings and of engine enclosures.


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"Etl:CTRICAL INSTALLATION OF BUILDINGS

(4) Adjacent area in which hazardous vapours are not likely to be released, such as stock rooms, electrical control rooms, and other similarIocations, may be, classified as non-: hazardous when adequately ventilated and when effectively cut off from the hangar itself 'in accordance with the provisions of Section 12. '13.8.2 Wiring and Equipment in Hazardous Areas (1) All fixed and portable wiring and equipment which is or may be installed or operated within any, of the hazardous locations defined in Clause 13.8.1 shall conform to the requirements of Section 12. (2) All wiring installation in or under the hangar floor shall conform to the requirements for Class I, Division 1 locations. (3) Wiring systems installed in pits or other spaces in or under the hangar floor shall be provided with adequate drainage and shall not be placed in the same compartment with any other service except piped com~ressed air. (4) Attachment plugs and socket outlets inhazardous locations shall be explosion-proof or shall be so designed that they cannot be energized while the connections are being made or broken. 13.8.3 Wiring Not within Hazardous Area (1) All fixed wiring in a hanger not within -a hazardous area as defined in Clause 13.8.1 shall be installed in metal raceways or shall be armoured cable, Type MI (Mineral Insulated) cable, or aluminium sheathed cable, except that wiring in' a non-hazardous location as set out in 13.8.1(4) may be of any type recognized in Section 8 as suitable for the type of building and the occupancy. (2) For pendants, flexible cord of the hard-usage type and containing a separate bonding conductor shall be used. (3) For portable utilization equipment and lamps, flexible cord approved for hard usage and containing a separate bonding conductor shall be used. (4) Suitable means shall be provided for maintaining continuity and adequacy of bonding between the fixed wiring system and the non-current-carrying metal portions of pendant fixtures, portable lamps and other portable utilization equipment.

306

EBCS-10 1995

ETHI9PIAN BUILDING

GODE STANDARD


13.8.4 Equipment Not within Hazardous Areas

(1) In locations other than those described in Clause 13.8.1, equipment which is less than 3.0m above wings and engine enclosures of aircraft and which may produce arcs, sparks, or particles of hot metal, such as lamps and lanipholders for fixed lighting, cutouts, switches, socket outlets, charging panels, generators, motors or other equipment having make-and break or sliding contacts, shall be of totally-enclosed type or· so constructed as to prevent escape of sparks or hot metal particles, except that equipment in areas described in 13.8.1(4) may be of general purpose type. (2) Lampholders of metal-shell-fibre-lined types shall not be used for fixed lighting.


EBCS-10 1-995307

SECTION

14

PATIENT CARE AREAS

14.1

SCOPE

(1) This Section of the Code applies to the installation of electrical wiring and equipment within patient care areas of hospitals and those portions of the electrical systems of hospitals designated as essential electrical systems.

14.2


(1) The following references contain provisions which, through reference in this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings: .

a) C22.1:1990

Canadian Electrical Code, Part I, Safety Standard for Electrical Installations, Sixteenth Edition.

b) NEC (Handbook):1991 National Electrical Code Handbook, Based on the .1991 (NEC), Seventeenth Edition.

14.3'

DEFINITIONS

(1) For the purpose of this Section, in addition to the terms defined in Section 1, the following definitions shall apply:

anaesthetizing location

any area of a health care facility where the induction and maintenance of..general anaesthesia are routinely carried out in the course of the examination or treatment of patients.

appUedpart

the part or parts of medical electrical' equipment including the patient leads which come intentionally into contact ~h the patient to be examined or treated.

308

EBCS- to 1995


SECTION 14: PATIENT CARE AREAS

body contact

an intentional contact at the skin surface or internally, bur not directly to the heart.

cardiac contact

an intentional contact directly to the heart by means of an invasive procedure.

casual contact

contact by voluntary action with a device that has no applied part and is not intended to be connected to a patient.

criticalcare area

a patient care area in which anaesthetics are administered, or in which cardiac contact between a patient and medical electrical equipment is frequent or normal.

delayed vital branch

that portion of an essential electrical system in which the circuits require power restoration within 2.0min.

emergency supply

one or more in-house generators of electricity intended to be available in the event of a failure of all other supplies and capable of supplying all the essential loads.

essential electrical sysem

an electrical system which has the capability of restoring and sustaining a supply of electrical energy to specified loads in the event of a loss of the normal supply of energy.

hazard index

for a given set of conditions in an isolated power system, the current, expressed in milliamperes and consisting of resistive and capacitive leakage and fault currents, that would flow through low impendence if the low impendence were to be connected between either isolated conductor and ground.

hospital

an institution, so designated by Ethiopian Ministry of Health, where patients are accommodated on the basis of medical need and are provided with continuing medical care and supporting diagnostic and therapeutic services.

intermediate care area

a patient care area in which body contact between a patient and medical electrical equipment is frequent or normal.


EBCS-10 1995

309


isolated system

an electrical distribution system in which no circuit conductor is connected directly to earth.

line isolation monitor

a device which measures and displays the total hazard index on. an isolated electrical system, and provides warning when the index reaches a preset limit.

normal supply

the main electrical supply into a building or building complex, and may consist of one or more consumer services capable of supplying all loads in the building complex.

patient

a person undergoing medical investigation or treatment.

patient care area

an area intended primarily for the provision of diagnosis, therapy, or care.

patient care location

a zone in a patient care area which has been pre-selected for the accommodation ofa patient bed, table, or other supporting mechanism, and for the accommodation of equipment involved in patient treatment, and which includes the space within the room 15m beyond the perimeter of the' bed in its normal location and to within 2.3m of the floor.

patient carf! location bonding point

a common bus at a patient care location, that is bonded to earth, and that serves as a common point to which equipment and other bonding connections can be made by means of a group of-jacks,

permanently connected equipment

equipment that is electrically connected to the supply be' means of connectors that can be accessed, loosened or tightened only with the aid of a tool.

.' total hazard index

vital branch

310

EBCS-10 1995

the hazard index of a given isolated system with all appliances, including the line isolation monitor, connected. that portion of an essential electrical system in which the circuits require power restoration within 10,Os.

ETHIOPIAN BUilDING CODE SYANDARD


14.4

CIRCUITS IN BASIC CARE AREAS

14.4.1 Branch Circuits

(1) The branch circuits supplying socket outlets and permanently connected equipment in basic care areas shall be supplied from an earthed distribution system. (2) A branch circuit which supplies socket outlets or permanently connected medical electrical equipment within a patient care location shall only supply loads within such location. (3) All branch circuits for a patient care location shall be supplied from a single panelboard, except branch circuits intended to be part of an essential electrical 'system, which shall then be permitted to be supplied from two panelboards, one of which is part of the essential system. 14.4.2 Bonding to Earth in Basic Care Areas

(1) Bonding conductors shall be insulated unless they are: a) installed in nonmetallic conduit; or b) incorporated into a cable assembly 'in such a manner that contact between any metal shield or armour, if it is present, and a bare bonding conductor is not possible.. (2) All socket outlets and other permanently connected equipment shall be bonded to earth .by copper equipment bonding conductors, sized not smaller than the minimum size required for circuit conductors and, except as permitted by the supplying authority, run with the circuit conductors in accordance with the following: a) Each multi-wire branch circuit shall be provided with its own equipment bonding conductor. b) Except as permitted by (c) and (d) below, each 2~wire branch circuit supplying' a socket outlet at a patient care location shall be provided with its own equipment bonding conductor. c) When the socket outlets at a patient care location are supplied from two 2-wire branch circuits in the same raceway, a single equipment bonding conductor shall be . permitted to be shared by the two circuits.


EBCS·10 1995

311


d) When socket outlet intended for a pair of adjacent patient care locations are supplied by three 2-wire branch circuits and one of the circuits is intended to be shared by both patient care locations, the three circuits shall be permitted to share two equipment bonding conductors. (3) Equipment bonding conductors required by (2) and (5) below shall terminate either at the panelboard supplying the branch circuits to the patient care location from which they arise or on an earthing bus which is bonded to that panelboard. (4) Each item of3-phase equipment shall be bonded to earth with an equipment bonding conductor which is: a) sized in accordance with Part I of Section 7 of this Code, but in no case smaller than 4.0mm2; and b) connected to its own terminal at the equipment and the panelboard. (5) Exposed non-current-carrying metal parts of communication, radio or television equipment, other than\' telephone sets, at a patient care location, if they could become energized, shall be bonded to earth by: a) connection to the bonding screw in the communication section of a buried and ganged metal outlet box, serving a patient care location; or b) connection to an equipment bonding conductor or earthing bus for that patient care location as identified in (3) above. 14.4.3 Socket Outlets in Basic-Care Areas (1) Socket outlets intended for a given patient-care location shall be located so as to minimize the likelihood of their inadvertent use for a patient-care location for which they are not intended. (2) Socket outlets which are located in areas that are routinely cleaned using liquids which normally splash against the walls shall be installed not less than 300.0mm above the floor. (3) Socket outlets located in bathrooms or washrooms within a patient care area shall be located: a) adjacent to the wash basin, and b) outside of any bathtub enclosure or shower stall.

312

EBCS-10 1995



(4) Socket outlets which are located adjacent to a washbasin in a patient care area shall be protected by an earth fault circuit interrupter of the Class At type. 14.5

CIRCUITS IN INTERMEDIATE AND CRITICAL-CARE AREAS

14.5.1 Branch Circuits

(1) The branch circuits supplying socket outlets and other permanently connected equipment in intermediate or critical care areas. shall be supplied from either an earth system meeting the requirements of Section 14.4 or an isolated system meeting the requirements of Section 14.6, except that all branch circuits, other than those supplying multiphase equipment, shall be 2-wire circuits. . 14.5.2 Bonding to Earth in Intermediate and Critical-Care Areas

(1) Bonding to earth in intermediate and critical ca.re areas shall conform to Clause.14.4.2 whether the supply is derived from an earthed or an isolated system. (2) If a patient-care-location bonding point is provided, if shall' be bonded to the panelboard serving the patient-care location with which it is associated by either: a) a bonding jumper connecting it to the bonding terminal in an enclosure which accommodates the bonding point along with socket outlets for a patient care location; or b) a copper conductor which is installed. for that specific purpose, and is run in the same raceway as the equipment bonding conductors serving that patient care location. 14.5.3 Receptacles in Intermediate and Critical Care Areas

(1) Socket outlets in intermediate and critical care areas shall: a) meet t~~q'uirements of Clau~e)4.4.3; and b) where supplied from an isolated system, be so identified. ~.;..

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t For definition of Class A earth-fault circuit interrupter, refer to Clause A.2, Annex A, Section 25.


EBCS-10 1995

313


14.6

ISOLATED SYSTEMS

14.6.1 Sources of Supply \

(1) The means of supply to an isolated system shall be:

\

\\ \

a) the secondary of one or more isolating transformers h~g no direct electrical connection between primary and secondary windings, .

b) a motor-generator set, or

c) a suitably isolated, battery-powered inverter supply.

(2) Where more than one single-phase isolated power system serves a singlelocation, the earthing busses of all of these systems shall be bonded together with a copper bonding conductor: a) having a total impedance not greater than O.20hm, and

b) sized not smaller than that permitted in Part I of section 7 of this Code.

14.6.2 Single-Phase Isolated Circuits

(1) Isolated circuits shall: a) not be deliberately earthed except through the impedance of an isolation sensing device (e.g., isolation monitor); b) have- overcurrent devices that will open all unearthed conductors simultaneously; c) unless prohibited by the Power Suppling Authority, be installed in non-metal raceways. (2) Any disconnecting means controlling an isolated circuit shall safely and simultaneously disconnect all unearthed conductors. (3) A single-phase isolated system shall include automatic means (a line isolation monitor), with an indicator located where visible to persons using the system, to monitor the impedance-to-earth of the system together with any loads connected to it. (4) Where a single-phase isolated system is employed, it shall supply: a) general-purpose socket outlets at:

314

EBCS-10 1995



i) ii) iii)

a single anaesthetizing location;

one or more patient care locations in a single room; or

a maximum of two patient care location.s'in separate but adjacent rooms,

provided that the alarm indicator clearly identifies the patient care locations affected by the fault; or

b) special purpose socket outlets at different locations or in different rooms, provided that the system is used only for the one purpose, and is arranged so that only one socket outlets can be energized at a time. (5) A single-phase isolated system which supplies only a single load via a single branch circuit shall meet the requirements of (1) through (3) above except that: a) overcurrent devices need not be installed in the isolated circuit; and

b) the use of a line-isolation monitor shall be optional.

14.6.3 Three-Phase Isolated Systems (1) A three-phase isolated system shall: a) supply only permanently connected equipment; and

b) meet the requirements of Clause 14.6.1.

14.7

ESSENTIAL ELECTRICAL SYSTEMS

14.7.1 Circuits in Essential Electrical Systems (1) An essential electrical system shall comprise those circuits that supply loads designated by the hospital administration as being essential for the life safety and care of the patient, and the effective operation of the hospital. (2) An essential electrical system shall comprise at least a vital branch, and may also include a delayed vital branch. (3) The wiring of the essential electrical system shall be kept entirely independent of all other wiring and equipment and shall not enter a fixture, raceway, box or cabinet occupied by other wiring except where necessary as in:


EBCS-10 1995

315'


a) transfer switches; and b) emergency lighting fixtures suppIi~dJr",m two sources.

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TRANSFER SWITCHES"

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7

:141 . (1pAll transfer switches shall be acceptable to the supply anther]

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(2) Automatic transfer switches used in essential electrical syste a) be el;~tr.ically operated and mechanically held; and b) include means for safe manual operation.

, (3) Manual transfer switches shall conform t9 the following: ){i_ ~ a) The switching means shall be mechanically held and the operation shall be by direct manpower or by electrical remote manual control utilizing control power from the supply to which the load is being transferred. b) A manual transfer switch which is operated by electrical remote manual control shall include a,means for safe manu'al mechanical operation. ;;:?;

c) Reliable mechanical interlocking (and.m the case of a switch operated by electrical remote manual control, electrical interlocking) to prevent interconnection of the normal and the emergency supplies of power shall be inherent in the design of a manual transfer switch, d) A manual transfer switch shall include a readily visible mechanical 'indicator showing the switch position.~;i/ (4) The vital and delayed vital branches shall be connected to the emergency power supply by means of one or more automatic transfer switches. 14.9

EMERGENCY SUPPLY

(1) An emergency supply shall be one or more generator sets driven by a prime mover and located on the hospital premises in a fire-resistant enclosure or room, and in such a manner as to minimize the possibility of flooding a~d damage.

316

EBCS-10 1995


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(2) The prime mover of the generating set, as specified in (1) above, shall be capable of operatiri!jndependently of supplies of r. . water and fuel from public utilities. (3) ~luei'supply sufficient to operate the prime mover under full load for at least 24.0hrs shalr"e st~;ed on the site. "l> ". "t-o.. -r.'"

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EBCS-10 1995

317

SECTION

15

INSTALlATION OF UGHTING EQUIPMENT

I

15.1

SCOPE

(1) This. Section applies to installation of interior and exterior lighting equipment. 15.2



(a)

C22.1:1990

Canadian Electrical Code, Part 1, Safety Standard for Electrical Installation, Sixteenth Edition.

(b)

IEE:1970

The Institute of electrical Engineers, Regulations for the Electrical Equipment of Buildings, Fourteenth Edition, Incorporating Amendments.

(c)

BS 8208:1985

British Standard, Artificial Lighting for Interior, Part 1.

(d) BS 5649 (EN40):1978:

BJitfsh Standard, Lighting Columns Parts 1,2, 4,5, 6, and 9.

15.3

INTERIOR LIGHTING EQUIPMENT

15.3.1

General

15.3~1.1

Material

(1) Material of lamps shall confirm, as regards the type of lamp, mechanical qualities and insulation resistance, to applicable IEC or other international standards.

318

EBCS-101995


.SECTION 15: INSTALLATION OF LIGHTING EQUIPMENT

15.3.1.2 Luminaire Construction (1) Luminaires shall be constructed from such material and so finished that their safety, performance or appearance does not deteriorate significantly during normal life when they are operated in the condition for which they are designed.

15.3.1.3 Voltage (1) Branch circuit voltages shall not exceed 230.0V-to-earth in dwelling units; and in other than dwelling units, voltages shall not exceed the voltage-to-earth ofnominal system 380.0V. Note:

Where 380.0Y line-to-line system is used, the control switch shall be of double-pole type and the .luminaire shall be earthed,

15.3.1.4 Pro.tection . (1) Incandescent luminaires and incandescent lampholders shall not be' connected to a branch circuit protected by overcurrent devices rated at more than 16.0A; but in other than dwelling units, they shall be permitted to be connected to a branch circuit protected by overcurrent devices rated or set at not more than 2O.0A. . (2) Tungsten halogen luminaries, incandescent moulded-base luminaries, and incandescent moulded-base lampholders shall not be connected to branch circuit protected by overcurrent devices rated or set at more than 40.0A. . (3) Fluorescent luminaries shall not be connected to a branch circuit protected by overcurrent devices rated or set at more than 16.0A except for circuits supplying fluorescent luminaries; only the rating of the overcurrent protection may exceed 16.0A, but shall not exceed 20.0A. (4) High intensity discharge (HID) luminaries shall not be connected to a branch circuit protected by overcurrent devices rated or set at more than: ~ 2O.0A where the input voltage to the luminaire is not more than 230.0V nominal,

but not exceeding 380.0V nominal; and b) 16.0A where the input voltage is above 380.0V nominal.


EBCS-10 1995

319


15.3.2 Location of Lighting Equipment 15.3.2.1 Near or over combustible material

(1) Luminaries and lampholders shall be placed or guarded in such a manner as to prevent ignition of any combustible materials. (2) Any shade or guard used for the purpose in (1) above shall be, besides limiting the temperature to which the combustible material may be subjected, suitable to withstand the heat from the lamp. 15.3.2.2 Show 'windows

(1) In show windows: a) no luminaries having exposed wiring other than a luminaire of a chain-suspension type shall be used; and b) no lampholders having a paper-fibber lining shall be used. 15.3.2.3 Clothes closets

(1) Luminaires installed in clothes closets: . a) shall be located on the ceiling or on the front wall above the door of the closet unless mounted on the trim of the sidewalls of the doorway and approved for the application; and b) shall not be of pendant type. 15.3.2.4 Luminaire in damp or wet locations

(1) Luminaries in damp or wet locations shall be approved for such locations and be so marked. 15.3.2.5

Control switch

(1) A light fitting connected to an installation by means other than a socket outlet shall be controlled by a switch which shall be arranged to disconnect all the supply conductors.

320

EBCS-10 1995


SECTION 15: INSTALLATION OF LIGHTING EQUIPMENT

(2) The switch required by (1) above shall be separate from lighting fitting and in a readily accessible position subject to the provisions (3) and (5) below, where applicable. (3) Where a switch has to be situated so as to be normally inaccessible to a person who is »>: using a bath or a shower, iris admissible for the switch to be placed adjacent to thenormal access door of the room, or to be of the type operated by insulating cord. (4) The switch or switches providing control of comprehensive lighting installation comprising more than one lighting fitting in non-domestic premises may be installed in separate rooms. (5) Where lighting fittings are installed over readily combustible material, every light fitting 'shall be controlled by an individual wall switch. (6) Where stairway in a dwelling unit has risers, the lighting shall be controlled by intermediate wall switches or their functional equivalent located at the head and foot of the' stairway, 15.3.3 Installation of Lighting Equipment

15.3.3.1

Live part,

(1) Luminaries, lampholders, and rosettes shall be installed so that no live part is exposed to contact while they are in use. (2) Where lampholders and switches have exposed accessible terminals, they shall not be installed in metalluminaire canopies or in open bases of portable lamps.

15.3.3.2

Support,

(1) Every luminaire, lampholder and rosette shall be securely supported. (2) Where a luminaire weighs more than 30;ON or exceeds 40.0cm in any dimension, it shall not be supported by the screw shell of the lampholders. (3) Where a non-metallic outlet boxof thermoplastic material, such as, for example, P.V.C, is used to suspend a luminaire, care shall be taken to ensure that the temperature of the box does not exceed 60°C; and the mass suspended shall not exceed 30.0N.


EBCS·10 1995

321

.I'

i


(4) Where the weight of a luminaire does not exceed lOO.ON, it shall be permitted to be supported by an outlet box that is mounted on a bar hanger.

a

(5) Where luminaireweights more than 100.0N, it shall be suspended independently of the outlet box, or by means of an acceptable fixture hanger with integral outlet box. 15.3.3.3

Outlet boxes to be covered

(1) Every outlet box used with lighting equipment shall be provided with a cover or covered by a luminaire canopy lampholder , rosette, or other device. 15.3.3.4 Recessedluminaries

(1) The recessed portion of every enclosure of a recessed luminaire shall be at least 12.5mm from combustible material at every point other than at a point of support. (2) Every recessed luminaire shall be-so installed that any adjacent combustible material is not subjected to temperature in excess of 90°C. (3) Recessed luminaries shall not ~ used when blanketed with thermal insulation unless the luminaries are marked and approved for this use. 15.3.3.5 Minimum height of luminllries

(1) Where a rigid luminaireor lampholder is located at a height of less than 2.1m above the floor and is readily accessible, the luminaire or lampholder shall be protected 'from mechanical injury by a guard or by location. 15.3.3.6 Luminaire exposed to flying objects

(1) Where luminaries are installed in gymnasiums or similar locations where the lamps are normally exposed to damage from flying objects, the lamp shall be guarded by one of the following means: .a) metal reflectors that effectively protect the lamps, b) metal screens, c) enclosures of armoured glass or suitable plastic material.

322

EBCS-10 1995


SECTION 15: INSTALLATION OF LIGHTING EUUIPMEN:r . .::L

'penir /ithin

15.3.3.7 Luminaire as a raceway

5) A ccessi

(1) Branch circuit conductors run through a luminaire shall be contained ir: which is an integral part of the luminaire except that the conductor of a 2-wic; 4-wire branch circuit supplying the Iuminaire may be carried through:

equin

a)

b)

5) Br

art of

ie

pui

i.3.4.~

.) wr

mnec ith a'

:) Th nctioi

ensu .ting.

I

fHIO

~

a) an installation of luminaries approved and marked for end-to-end ass; ,.;. a continuous channel; or b) luminaries which are connected together by acceptable wiring metl.: (2) Ballasts located within luminaries shali be deemed to be sources of conductors supplying the luminaries shall:

:~,

,.,ceway "',re, or

i-,

farm

:.r, " 'the

a) have a temperature rating not less than90OC;

b) be of type listed in:

i) Section 4, Annex B,as being suitable for use in raceway; or ii) Section 4, Annex B, as being suitable for use :in accordance with this Clause, provided that conductors are not smaller than 2.5mm 2 and do not extend beyond the luminaries through raceway more than 2.0m long.

5.3.4.~

l) Br. iring npaci

r,

15.3.4

Wiring of Lighting Equipment

15.3.4.1

Wiring ()j.luminaries

(1) .All-electricalwiringon orwithin a luminaire, beside ensuring its electrical safety, shall: a)bene:atly arranged without excess wiring;

b) be not exposed 10 mechanical injury;

C) be arranged so that it is not subject to temperatures above those for which it is

approved; and

d) be free from joint or tap Within.an armor stem.

15.3.4.2 Colour coding

,(1) Notwithstanding the requirementsofSection 4 with regard to the colours used for identifyingconductors,acontinuous-coloured tracer in the braid of individual braided conductor shall be permitted for thesu,pplyconductofs of a luminaire.


EBCS-10 199b

323

ELECTRICAL INSTALLATION OF BUilDINGS

15.3.4.3 Conductor cross section and insulation

(1) Luminaries shall be wired with a conductor at least O.5mm2 cross sectional arc a, having insulation suitable for voltage and temperature to which the conductors may be subjected. 15.3.4.4 Conductor on movablepans

(1) Stranded conductors shall be used on chain-type luminaire and other movable parts of lighting equipment. (2) Conductors shall be arranged so that the weight of the luminaire or that of the movable parts does not place undue tension on the connections. (3) All conductors which supply movable parts of lighting equipment shall be protected against mechanical injury. 15.3.4.5 Pendant conductors

(1) Where pendant conductors are longer than 900.0mm, they shall be twisted together. 15.3.4.6 Recessed luminaire wiring

(1) Conductors for wiring recessed luminaire, branch circuit and tap connection shall have insulation suitable for the temperature encountered. (2) Branch circuit conductors shall be permitted to be run directly to the luminaire. (3) Tap connection on" conductors shall: a) not be smaller than l.Dmm'' copper run in a factory-installed raceway or, if raceway is provided but not factory assembled, smaller than 2.5mm2; b) extend at least 150.0mm from the raceway; and c) be installed in a raceway extending at least 450.0mm but not more than 2.0m from the luminaire, and terminate in an outlet box located not less than 300.0mm from the luminaire. (4) The outlet box referred in (3c) above shall be accessible, and if access is through the opening for mounting the luminaire or through some other opening in the ceiling, this

324

EBCS-10 1995

ETHIOPIAN BUilDING CODE STANDARD

ELECTRICAL INSTALLATION OF aUtLDINGS

15.:'-5

Earthing of Lighting Equipment

15.3.5.1 Genetal (1) Non-current-carrying metal parts of luminaries and associated equipment shall be earthed in accordance with Part I of Section 7.

15.3.5.2

Lampholders

(1) Where centre-contact screw Iampholders are connected to a source of supply having an earthed neutral conductor, the outer or screwed contact shall be connected to that conductor.

(2) Where lampholders in (1) above are used in circuits having neither pole connected with earth or itt any damp situation in which they can readily be touched by a person in contact with or standing on earthed metal, they shan be provided with a protective shield of insulating material or shall be placed or safeguarded so that neither the lamp cap nor the outer or screwed contact of the Iampholder can inadverntly be touched when the lamp cap is engaged with the contact

15.3..6

Electric-Discharge Lighting Systellls Operating at 1000.0V or Less

15.3.6.1

Transformer

(1) Oil,:.fil1ed transformers shall not be used. 15.3~6.2

TltemittJ p1"otection

(1) Luminaries which employ fluorescent lamps shall have thermally protected ballasts except where the ballasts are of the simple reactance type.

15.3.6.3

AUXiliary equipmettt

(t) Reactors, capacitors, resistors, and other auxiliary equipment shan be: a) enclosed within the liminaire; b) enclosed within an accessible; permanently installed, metal cabinet where remote from the luminaire, or

e) acceptable for use without an additionalenclosure.

326

EBCS..10 1995

ETHIOP1AN BUILDING CODE STANDARD


(2) The metal cabinet, if not part of the luminaire, shall he installed as close as possible to the Iuminaire. (3)- Where display cases are not permanently installed, no part of a secondary circuit shall . . . be included in more than one case. 15~3.6.4

Control

(1) The luminaries and lamp installations shall be controlled by a switch, circuit breaker, or contactor. (2) Where a switch is used as in (1) above, it shall: a) have a current rating of not less than twice the current rating of the lamps or transformers;

b) be a type approved with the assembly; or

c) be a manually-operated general use 380.0V a.c. switch.

15.4

OUTDOOR LlGIITING EQUIPMENT

15.4.1 General 15.4.1.1 Hazard

(1) In outdoor lighting installations, either decorative lighting or illumination of outdoor areas, the protection of the installation and safety from shock hazard shall be the major concern and the fire hazard of the minor or of secondary nature.

15.4.1.2 Ball4st protection (1) Luminaire which employ fluorescent lamps shall have thermally protected ballasts except where the ballasts are of the simple reactance type. 15.4.1.3 Overcurrem potection

(1) Overcurrent protection shall not be provided in a high-intensity discharge luminaire or a separate ballast box unless the combination is approved for the purpose and so marked.


EBCS..10 1995

327


15.4.2 Permanent Outdoor Floodlighting Installation 15.4.2.1 General

(1) Clause 15.4.2 shall apply to permanent, outdoor installations of floodlights of 300.0W or larger where the floodlights art; mounted on poles or towers, 15.4.2.2 Service equipment

(1) Service equipment shall comply with Section 5 of this Code; and where indoor installation is installed outdoors, it shall be installed in an acceptable weather-proof enclosure. 15.4.2.3

Wiring methods underground

(1) Underground wiring shall be run: a) where acceptable, in rigid steel or rigid aluminium conduit; b) in non-metallic underground conduit; c) as lead-sheathed armoured cable, mineral-insulated cable, or aluminium-sheathed cable; or d) as conductors or cable assemblies acceptable for earth burial. (2) Conductors buried directly in the earth shall be of types suitable' for use in wet locations. (3) Suitablecorrosion-resistant protection shall be provided for aluminium sheathed cables and aluminium conduits, and also for mineral-insulated cable, if used where materials coming into contact with the cable may have a deteriorating effect on the sheath. 15.4.2.4

Wiring methods on poles

(1) All electrical equipment on a pole shall be controlled by a switch which can be locked in the "Off' position, and each pole shall be provided with a prominent sign warning against climbing the pole until the switch is "Off' unless all conductors and live parts other than those used for pole-top wiring are guarded against accidental contact in one of the following ways: .

328

EBCS-10 1995



a) The conductors are run in rigid or flexible metal conduit, as in mineral-insulated cable, or up the centre of steel, aluminium, or hallow concrete poles. b) The conductors and live parts are kept at least l.Om from the climbing ladder or climbing step. c) Barriers are provided between conductors or live parts, or both, and the climbing ladder so as to prevent a likelihood of contact by the climber. .' (2) Conductors running up the centre of poles shall be supported so as to prevent injury to the conductors inside the pole and so as to prevent undue strain on the conductor where they leave the pole. (3) Where vertical conductors, cables, and earthing conductors are within 2.5m of locations accessible to unauthorized persons, they shall be provided with a covering which gives acceptable mechanical protection. (4) On wood poles, for earthing conductors from lightning arresters, the protective covering specified in (3) above shall be of wood moulding or other insulating material giving equivalent protection. (5) Where there is more than one branch circuits on a pole top, the feeders shall be run to a distribution panelboard which shall be either weather-proof or installed in a weather proof enclosure. Note:

The panelboard may be omitted where there are two branch circuits on a 230/380.0V circuits with a common neutral Iineand where there are three branch circuits on a 230/380.0V,3-phase, 4-wire circuits.

(6) Pole-top branch circuit wiring, exclusive of leads approved with floodlights to which they are connected, shall be run: a) as lead-sheathed cable or rubber or thermoplastic-insulated, moisture-resistant types of conductors installed in rigid conduit; or b) by special permission, as insulated or uninsulated exposed wiring provided that: i) the wiring is supported on a suitable insulator; ii) the wiring is controlled by a switch which can be locked in the "Off' position; and iii) the pole is provided with a prominent sign warning against climbing it until the switch is "Off'.


EBCS-10 1995

329

ELECTRICAL INSTALLATION OF BUILDINGS - -----

-- -._------~-- , . - - - - - - - - - - - - - - - - - - - - - - - - - -

(7) There shall be no joints or splices concealed within conduit; but open taps and joints may be made in pole-top exposed wiring provided the joint or lap is given insulation equivalent to that on the conductors jointed. (8) Transformers shall comply with the following: a) If mounted on floodlight poles, all live parts shall be guarded as required by (1) above. b) If mounted on poles, the bottom of the transformer shall be at least 5.0m above

locations accessible to unauthorized persons. c) If located on platforms on the ground, they shall be completely enclosed so as to prevent access by unauthorized persons or they shall be surrounded by a protecting /'

fence,

(9) Switches controlling floodlights shall comply with the following: a) A switch on the primary side of a transformer shall be capable of making, and interrupting the full-load on the transformer. b) Switches controlling floodlights from tIre secondary side of a transformer shall have a current rating not less than 125% of the current requirements of the floodlights they control. c) Switches shall be capable of being' operated either by remote operation or by proper guardingwithout exposing the operator to danger of contact with live parts. d) Switches shall be capable of being locked in the "Off' position. The secondary earthed-circuit conductor may be earthed by interconnecting to the primary earthed circuit conductor provided that: (10)

a) the primary is earthed at the transformers, and

b) interconnection is made at the transformer.

Except for isolated metal parts such as cross bars, bolts; insulator pins, and the like, all non-current-carrying metal parts of the electrical equipment at the pole-top shall be bonded together and, if within reach of any earthed metal, they shall be earthed. (11)

330

E8C8-10 1995


-


15.4.3

Exposed Wiring for Permanent Outdo".. Lighting

15.4.3.1

General

(1) Clause 15.4.3 shall apply to exposed wiring for permanent outdoor lighting other than floodlighting where the circuits are run between buildings, between poles, or between buildings and poles.

15.4.3.2 Conductors (1) Conductors shall be stranded copper, not less than 205m2, and shall be: a) of a type suitable for exposed wiring where exposed to the weather; b) of the rubber-insulated type suitable for exposed wiring where exposed to the weather when lampholders of a type which puncture the insulation and make contact with the conductors are used; or c) of the moisture-resistant, rubber-insulated type suitable for exposed wiring where exposed to the weather if cabled together and used with messenger cables.

15.4.3.3 Use of insulators 15.4.3.3.1 Conductors attachment (1) Conductors shall be securely attached to insulators. at each end of the run if a messenger is not used and at the intermediate points of support, if there are any. 15.4~3.3.2

Type of insulator

(1) Insulators at the ends of runs shall be of the strain type unless the conductors are supported by messenger cables. 15.4.~.3.3

Split knobs

(1) Split knobs shall not be used.


EBCS-10 1995

331


15.4.3.3.4 Height of conductors

(1) Conductors supplying lamps in parking lots, used-car lots, drive-in establishments and similar commercial areas shall be maintained such that the conductors or the bottom of a lamp fed from the conductors, whichever is lower, shall have a clearance of not less than 4.0m above grade at any point in a run, except that where a driveway or through fare exists, this clearance shall not be less than 4.0m. 15.4.3.5

Spacing from combustible material

(1) Conductors and lampholders shall be maintained at a distance not less than 1.0m from any combustible material except for branch circuit conductors at the point of connection to buildings or poles. 15.4.3.6

Spacing of conductors

(1) Conductors shall be separated at least 300.0mm from each other by means of insulating spacers at intervals of not more than 4.5m unless the conductors are secured to and supported by messenger cables. 15.4.3.7

Lampholders

(1) Lampholders shall: a) be of weatherproof types, with moulded insulating bodies;

b) be of types having either:

i) permanently attached leads; or ii) terminals of a type which puncture the insulation and make contact with the conductors; c) have, when with permanently attached leads, the connection to the circuit wires staggered where a cabled assembly is used.

332

EBCS-10 1995



15.4.3.8

Use of messenger cables

(1) Messenger cables: a) .shall be used to support the conductors: i) if lamp holders having permanently attached leads are used, and the span exceeds 12.0m; and ii) in all cases where lampholders having termination which puncture the insulation are used; b) shall be securely attached at each end of the run and shall be earthed. 15.4.3.9

Construction of messenger cables

(1) Messenger cables shall be of galvanized steel, copper-coated steel, or stainless steel, and shall be of a stranded construction with no less than seven strands. (2) The effective ultimate strength of a messenger cable shall not be less than 3 times the calculated maximum working load and in no case shall the individual strands be less than: a) 1.168mm in diameter in the case of galvanized or copper-coated wire; or

b) 1.112mm in diameter in the case of stainless steel wire.

15.4.3.10 Branch circuit loading and protection

(1) Branch circuits shall be protected by overcurrent devices rated at not more than 32.0A. (2) The total load on a branch circuit shall not exceed 80% of the rating or setting of the overcurrent devices.


EBCS-10 1995

333

ANNEX'

A(NORMATIVE)

LIGHTING COLUMNS,

A.1

TERMS IN THE FIELD OF LIGHTING COLUMNS

Lighting column

a support intended to hold one or more lanterns, consisting of one of more parts: a post, possibly an extension piece and, if necessary, a bracket. It does not include columns for catenary lighting.

nomi1lll1 height

the distance between the centreline of the point of entry of the lantern and the intended ground level for a column planted in the ground, or the flange plate, for a column with a flange plate as shown in Figure A.1.

/."~

,')

I '

.~ J . II

'~,. , ~

'L"

"L.,;"Ii ...

...' -.

Figure A.l Nominal height

334

EBCS",10 1995



posMOp column

a straight column without bracket to support the lantern (post-top lantern) directly.

column with bracket

a column to support a lantern or lanterns (side-entry lanterns) by means of one or more brackets which are integral with, or demountable from, the column.

bracket

a component used to support a lantern at a definite distance from the axis of the lower straight portion of a single, double or multiple form column and integral with, or demountable from, the column.

bracket projection

horizontal distance from the point of entry to the lantern to a vertical line passing through the center of the cross section of the column at the ground level as shown in Figure A.2.

I

the shape

of the bracket

is not ~pecified

in this standard

'\ ).

.i.> Figure A.2 Bracket projection bracket fixing

the connecting part on a column for securing a separate bracket. It may be of the same size or a different cross section from the column.

lantern .fixing

the connecting part on the end of a post-top column or of a bracket for securing a lantern. It may be the end of the column or the bracket itself or an additional part having the same or a different cross section from the column or bracket.

ETHJOPIAN BUILDING CODE STANDARD

EBCS-10 1995

335


angle between the axis of the lantern fixing and the horizontal.

lantern .fixing angle

opening in a column for access to electrical equipment.

door opening

opening in a column below ground for cable entry.

the length of a column below the intended ground level as shown in

Figure A.3.

cable entry slot planting depth

,..~

)

"

"'",",---",,,'

t

,

1b,Plan.hng dep.tl\

Figure A.3 Planting,depth

plate below ground level fixed to a planted column sinking into the ground and to help prevent the column overturning as shown in Figure A.4.

base plate

~/-~

,)

"

Base plate

Figure A.4 Base plate

336

EBCS-10 1995 _



a plate with an opening for cable entry, attached rigidly to a column which is surface mounted, to allow it to be secured to a concrete foundation or other structures as shown in Figure A.S.

flange plate

,/':.-f'

)

. '-----

'I

!

Flange plate

Figure A.5 Flange plate A.2

DIMENSIONS AND TOLERANCE

A.2.1

Requirements

The dimensional requirements are specified except that the connection dimensions in Clause A. 2.7 represent a recommended choice.


EBCS-10 1995

337

ELECTRICAL INSTALLATION OF BUiLDINGS it

A.2.2 Post top columns, main dimensions (in meters)

~ I.

For to.lerana:s for d~mcnsions and shape see clause 8

I

'NClmin.1

height

h

3 _-------- 4 --.-------- ...

1

-

5 6

--

.c:

S 10

.

12

-

1'1

._.15 ..

__

__ _ .- ...... _-

18

.....

1 1

For dimensions for door openings and cable entry s"lots see clause A2~~

I

10

$1. -,;n

-. +.

...- +

1. 1

'1;9

-:

llY

:W#f/.,f'W;Vv :'

I

I

@

For base plate s"clalne

Type Al

A.?.s

Type A2

For column foundation see clause A

338

.... ..__

20

EBCS-101995

". $ @j

For llange :plate see -clause 'AI.'

Type A3

1.5

ETHlOPIANBUILPfNG CODE STANDARD


A.2.3 Columns with brackets, main dimensions (in meters)

Connection dimensions heli clouse A2.1) Lantern fixing ong'lt 5" or 15"

The shape of the bracket not specified In this standard

'S

'\

)

For tolerances for dimensions and shape. see clause Al.8

<>'

Nomlnll h.lght

h

Pro/.ctlon

w"

5

-e

6 8

I

I

:i9~

~

.~

w-

f

For base plale 142.5

~ see clause Type 81

Type 82

For column foundallon see clause

1.25

10

2

12

3

15

For dimensions for door opening,'and cable entry slots see clause "'2.4

+

0.75

18

+

~

~

m

For flange plate see clause A2. ~

Type 83

A2.5

11 It is 'ecommondod Ihll W l!ono,"lIy should b. equll 10. 0' loss Ihon.1


EBCS-10 1995

339


A.2.4 Door openings and cable entry slots (dimensions in millimetres)

.----~

\

, '>""

-.

// ---

. . ' ./

\

~I

'#t f ; I'\.~ b

•

'"

",.

"

I'

fQ

I

a

b

200 300

__400

.

@] I

Position of door 4) and cable entry slot

i

-, ~. I

,50

~

:1 a

a

<" <·1

U11

1 ~

o

U1

.

,:-' /.

-

85

100 .----.- 500 100 500

120

600

115

600

130

I

F,'Ju,,:,, A2·3

Fl! a

75

680 11

95 11

680 1 )

130 11

900 11

130 11

1

1=(tur~ A;2.+

Dimensions of cutout

1) 2) 3) 4)

Supplementary dimensions for concrete columns. For metal columns only. It is recommended that this dimension be approximately 600mm, but in no case shall it be less than 30Omm; no maximum is specified. It is recommended that the door opening is positioned parallel to the bracket on the side away from the direction of traffic.

340

EBCS-10 1995



A.2.5 Column foundation, planting depth and base plate (dimensions in millimetres)

Nominal height

Planting depth

h

U1)

m 0<5

600

800

1000

6

800

1000

1200

8

1000

1200

1500

10

1200

1500

1700

12

1500

1700

2000

15

1500

2000

2500

18

1500

2000

20

1800

-

300 x 300 or 400 x 400

+

.~ ""1-~J

I I%:a.

I

~\

-

~t

Ij

c

E

-.t

Figurll

1)

A2·5a

Figurll

The planting depth, e, shall be selected from the values given in the table taking into consideration the calculations made before hand and the ground conditions.


EBCS-10 1995

341

ELECTRICAL INSTALLATION OF eUILDINGS A.Z~6

Flange plate (dimensions in millimetres)

f ~.'.' ...::--: . . '. r

.

.

.

. \.. )

/

.~

"= I:

II

/

. --II .t-"" I

,:: I

...

I.

I

d2

.

.... .---_-

, ~ _

I

'r

-I

~

Figure

Figure

I

h

A2.'

A 7. 7

c

m ~

5

s1l

I

'r

.

-
Ivumln.

Il..

l

tJ

•.

I

t.J 1 III

I,

"1

. ..

..

~

L=: Figure

a

d 1 1l

r

A

J .t

2~B

d 1 1)

d2

260

8

200

M18

'" 12

400

10

300

M24

~20

400 500

,20

300 400

M27

I

M18

22

400

M24

30

600

M27

33

700

1) These dimensions shall be checked by calculation.

342

EBCS.,10 1995

,11

min.

min.


I I

i I I

I i

SECTION

Al.7

15: INSTALLATION OF L1GH'ING EQUIPMENT

Connection Dimensions for Lanterns (in millimetresjv d . 1

;1

~j

j

Fil/ure

A2.,.1

Fillurll

A2.~

d1 3 1

i1

;£0

70

76

130

102

250

;: . . .

(I)

P

Pon lop 'anlurns

d23 1

Figure

Figure

/'2

.!. 42

100

Gll

100 250

A 2. lOb

Sido entry lanterns

Fi,urt. 1) 2) 3)

Al. 11

See clause A..2.1. This design does not apply to concrete columns. Diameters of steel spigots should be as given in ISO 64-1974 "Steel tubes, outside diameters" for steel tubes of the nearest size.


EBCS-10 1995

343

SECTION

16

FIRE ALARM SYSTEM AND FIRE PUMPS

16.1

SCOPE

(1) This Section describes the essentials of the fire alarm systems and applies to the installation of local fire alarm systems and fire pumps.

16.2


(1) The following references contain provisions which, through reference in this text, constitute

provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings. a) BS - CP 1019:1972 .

The Installation and Servicing of Electrical Fire Alarm System.

b) C22.1:1990

~anadian Electrical Code, Part 1, Safety Standard for Electrical Installations, sixteenth Edition.

c) DIN 57833:1982

Danger Alarm Systems for Fire, Hold-up and Intrusion, Parts 1 and 2.

d) .Euro Standard, En 54:1976

Component of the Automatic Fire Alarm Systems, Parts 1 and 5.

16.3

DEFINITIQNS

(1) In addition to the terms defined in Section 1, the following definitions shall apply in this Section:

344

EBCS-10 1995


SECTION 16: FIRE ALARM SYSTEM AND FIRE PUMPS

smoke

particulate product of combustion generated by fire, whether this be of smouldering or open-flame type.

sounders

devices in which electric signals are converted into sound signals.

/antem-light

a glazed construction standing above the surface of a roof, designed to admit light to the space below.

alertingfacility

a facility which issues the fire alarm - e.g., by means of audible and visual signalling devices - and which is not contained in the fire alarm control and indicting panels.

automatic fire alarm system

a system which detects the occurrence of fire in its incipient stage and immediately signals this without human intervention.

automatic fire detector

a part of a fire alarm system which, either continually or at periodic intervals, observes a suitable physical and/or chemical identifier for detecting a fire in the monitored area.

heat detector

a detector which respond to an increase in temperature.

smoke detector

·a detector which responds to products of combustion and/or pyrolysis (suspended matter) contained in the air.

flame detector

a detector which responds to the radiation emitted by fire.

fire identifiers

physical variables which are subject to measurable changes in the environment of a fire in its incipient stage; e.g, rise in temperature, smoke, flame radiation.

fire alarm signal

a signal which alerts the fire fighting forces.

fire alarm system

the entirety of the equipment and parts, matched for correct interaction, used in a fire alarm system.

alarm box control room

a facility from which the necessary fire fighting measures can be initiated at all time.


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345


false alarm

a fire alarm signal caused by technical malfunctions in the fire alarm system (alarm resulting from disturbance) or spurious alarms resulting from the fire detector being "mislead".

non-automatic (manual) fire alarm devices

16.4

alarm devices which can be used to initiate the fire alarm signals manually.

DESIGN CONSIDERATION

16.4.1 General

16.4.1.1 Design (1) Fire alarm systems shall be designed so that: a) the earliest possible definite warning of fire (i.e., avoiding false alarm) is given to all personnel immediately concerned; b) it is capable of indicating the locality of the origin of the fire alarm as to facilitate the safe evacuation of the premises and to direct fire fighters; and c) it performs its function with great reliability.

16.4.1.2 Equipment and power supply (1) The equipment, wiring and use of the fire alarm system shall be exclusive to that system and its power supply shall be provided independently from those for any other equipment.

16.4.1.3 A/arm signals (1) The audible and visual alarm signals shall be used solely for the fire alarm purpose, and these signals shall not reset automatically.

16.4.1.4 Location of the alarm control and indicating panel (1) The fire alarm and associated indicating panel shall be sited where they can be undet constant observation when the premises are occupied and shall be accommodated in a room: a) in the direct vicinity of the main entrance;

346

EBCS40 1995


-------------------

----


b) that provides adequate protection against ambient influences which could impair operations; e.g. vibration, smoke, dust, gasses, vapour, etc. produced by machinery, etc; and c) that has room climate suitable for proper operation of the fire alarm control and indicating panel.

16.4.1.5 Explosive or flammable atmosphere (1) If it is necessary to install the fire alarm equipment or wiring in situation where there may be an explosive or flammable atmosphere, the applicable Clauses of Section 12 shall be observed.

16.4.2

Circuit Design

16.4.2.1

General

(1) The design of a fire alarm circuit shall provide facilities for rapid and reliable transmission of initiated signals when manual call points or detectors are operated and when specified faults occur to control and indicating equipment.

16.4.2.2 Number of circuit elements (1) For sake of reliability, the number of circuit elements in the fire alarm system on which alarm actuation depend shall he kept to a minimum.

16.4.2.3

Transmission circuitry

(1) Any resultant signal shall be transmitted by the simplest possible circuitry to sounders and other indicating equipment and to any equipment which is to be operated by the fire alarm system; e.g, fire extinguishers, fire protection traps, local plant facilities, etc.

16.4.2.4

Fault signal discrimination

(1) Where chances of malfunction are high in a fire alarm system, discriminatory circuit shall be incorporated in the system so that false alarms _are identified.


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347


16.4.2.5

Origin of call indication

(1) Except in buildings where fire can be located without delay, the fire alarm system shall include an indication panel designed to show clearly the location of the origin of the alarm. Note: To meet this requirement, suitable zones should be defined throughout the building so that all the detectors and/or manual call points in anyone zone are connected to an indicator exclusive to that zone.

16.4.3

Manual Call Points

16.4.3.1 General (1) A manual call point shall be operated by a spring-loaded switch which is held in "non-alarm" position and protected from accidental operation by a cover usually of glass. Breaking this glass cover releases the switch to an "alarm" position and the system starts to operate.

16.4.3.2 Construction and requirements (l) Manual call points shall:

a) be constructed of pressed metal, cast metal, or plastic materials so that they will not be adversely affected' by the ambient temperature; . b) be rigid enough in construction to withstand the abuse to which they are Iikely to be subjected, without deterioration or reduction in their ability to operate effectively when required to do so; c) have contacts that are capable of operating satisfactorily during the design life of the installation; d) be coloured "signal red" over at least 50% of their visible area; e) have replaceable glass cover'; breaking the glass shall automatically operate the call point, and shall include description of the method of operation" by a concise inscription

• It is recognized that there are situations, e.g. food processing areas, where this type of call point is unacceptable and there may be no alternative to using a suitable manual call point of the toggle-switch type with safeguards against accidental operation.

•• The method of operation in an installation should be identical unless there is special reason for variation.

348

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ELECTRICAL INSTALLAT~ON OF BUILDlNGS

16.4.4.2

Detector types

(1) If development of a smoldesing fire is anticipated in the incipient stage of fire (intense smoke generation, very little or no flame radiation), smoke detectors shall be .used. {2) If a rapid development of the fire is anticipated as early as in the incipient stage of a fire .(intense heat generation, intense flame radiation, and generation ofsmoke), smoke detectors, heat detectors, flame detectors, or combinations of the various types of fire detectors shall be used. Note: The fact is that combustion is not always accompanied by flame and the reflected radiation effect restricts the

application of flame detectors.

(3) Jf smoke damage is anticipated as early as the incipient stage of a fire owing to .room occupancy (risk to human life, materials and goods sensitive to smoke), smoke detectors shall be used. (4) If a very rapid development of the fire is anticipated with a high degree of probability, an automatic extinguisher system shall be considered. (5) If it is not possible to predict or anticipate the development of a fire in the alarm area, special investigation shall be conducted to assist in selecting the particular type of required fire alarm detectors.

16.4.5

Sitting of Detectors

16.4.5.1

Monitoring

(1) Building and installation complexes shall be monitored or covered completely and each effectively enclosed space shall be considered separately for this purpose in accordance with the limits of spacing for the types of detectors concerned. Notes:

i)

ii) iii)

350

If, for some reason a fire alarm system is not installed throughout a building or a related series of buildings, the criterion shall be that the system will cover all of an area having physical boundaries of such a nature as to provide adequate fire separation or all of an area surrounded by sufficient open space; e.g. roads, to provide adequate fire separation. Voids not more than 800.0mm in height need not necessarily have independent monitoring. Small lavatories and water closets need not have independent monitoring but; may rely upon that provided in a lobby common thereto.

EBCS-10 1995



16.4.5.2 Sectioned rooms (1) Rooms divided into sections by walls, partitions or storage racks reaching 300.0mm of the ceiling or where goods might be stacked in defined areas to a corresponding height, shall have detectors for each section or passageway.

16.4.5.3 Flue-like openings (1) Hoists, elevators and similar flue-like openings shall be monitored by detectors at the top.

16.4.5.4 Staircases (1) Staircases shall be monitored by detectors on each floor.

16.4.5.5 Lantern lights (I) Lantern lights shall be monitored by detectors.

16.4.5.6 Special monitoring (I) Due to the requirements of the use to which any room, space, area or void is to be put or to its structural features, installation of additional detectors shall be considered,

16.4.5-.7

Height consideration

(I) Generally, the inter-relationship between the suitability of the various types of fire detectors and room height indicated in Table 16.1 shall be observed.

16.4.6 Sitting of Heat Sensitive (point) Detectors 16.4.6.1 Position relative to ceiling

(1) Heat sensitive point detectors shall be mounted so that their heat sensitive elements are positioned not less than 25.0mm and not more than 150.0mm below the ceiling or the underside of the roof.


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Table 16~1 Suitability ofdeteetors and room height

Smoke detector s

.

Room height

Heat detector$ Cat. 1

Cat. 2

.. Flame detectors

Cat 3

Upto 20.0m

W

W

W

W

R

Upto 12.0m

R

W

W

W

R

Upto 7.5m

R

R

W

W

R

Upto 6.0m

R

R

R

w

R

R

R

R

I

Upto 4.5m R - Suitable

R

R

W-= Unsuitable ,

i6.4.6.2 Limits of spacing

(1) The spacing limits indicated on Table 16.2 shall be observed in sitting detectors. (2) Notwithstanding the requirement in (1) above, the maximum spacing between detectors cannot apply in all directions since the area limit shall be observed, but detectors shall not be mounted closer than 500.0mm to any outside walls, separating walls or dividing partitions. Table 16.2 Spaeing limits for sitting detectors

Maximum floor area to be covered by one detector [m 2] 50.0

Maximum (hQrizontal) distance apart between centers [m]

Maximum (horizontal) dlst~nce from any outside walls~ separating walls or dividing partitions [m]

in general

In corridors

In general

In corridors

10.0

15.0

3.5

7.5

• In special buildings such as churches, mosques, museums and castles, it may be that detectors can only be arranged at a great height under certain circumstances. This will mean that an early fire warning cannot be . guaranteed. This render the use of the fire alarm less worthwhile.

•• Detectors are sub-divided into three response categories in line with the differing ceiling heights. Sensitive detectors (e.g. detectors of response category 1) may be used for high ceiling.

352

EBCS-10 1995


.


16.4.6.3 Ceiling (1) Where ceilings are crossed by beams, girders or other structural features having a depth of SOO.Omm or more, at least one detector shall be installed in each "pocket" formed between such features, and these detectors shall not be less than SOO.Omm from any beam, guider or wall.

16.4.6.4 . Single truss and northlight roofs (I) One row ofdetectors shall be sited along the apex of each roof or bay; these and any further detectors needed to cover the area shall be spaced in accordance with 16.4.6.2.

16.4.6.5 Floor openings (1) Detectors shall be so sited that at least one on each floor is suitably placed within I.Sm of hoists, elevators, stairways, well-holes, and similar openings to the floor above.

16.4.6.6 Lantern lights (1) Detectors fitted in lantern lights shall be protected from direct sunlight; fixed-temperature type detectors shall be used in such location. Note: Suchlocations are liableto rapidtemperature variations due to combination of solarand internal heatingand, thus, fixed-temperatere-type .detectors are recommended.

16.4.6.7 Ambient temperature (1) Where high and/or suddenly rising temperature owning to natural conditions or conditions resulting from normal operation are likely, fixed-temperature detectors shall be used. (2) The static response temperature of the detector section shall lie between lOoe and 3Soe above the maximum temperature which can occur in the vicinity of the detector; and the maximum temperature setting shall not exceed 88°e.

16.4.7

. Vibration Combined with Rapid Temperature Change

(1) If detectors have to be fitted where they will be subject to shock and/or vibration and may also experience rapid temperature changes (e.g., in covering hoist apertures), a fusible alloy fixed-temperature-type shall be used. Note: Vibration coinciding withrising, although not dangerously rising, temperature couldinducefalsealarmsfrom other types.


EBCS-10 1995353

ELECTRICAL INSTALLATION OF BUilDINGS

16.4.8

Sitting of Heat-Sensitive (Line) Detectors

(1) These detectors are affected by the same phenomenon as the point detectors, and the recommendations given in Clause 16.4.6 shall be complied with.

16.4.9

Sitting of Smoke-Sensitive Detectors

16.4.9.1

CTeneral

(1) Smoke detectors shall normally be sitted at the highest parts of the enclosed areas, and shall be mounted so that their sensing area is not less than 25.0mm or more than 600.0mm below roof ceiling, except as may be indicated by site tests,

16.4.9.2

Heat barrier

(1) The sitting of smoke detectors shall be arranged to take the effects of heat barrier. Note: Warm air naturally collects under ceiling and in the apices of pitched roofs.. In some circumstances, this warm air can form what is usually known as heat barrier to the products of combustion rising from fire which is producing little change in the ambient condition. The combustion products from such a fire will spread out

below the heat barrier in the same way as they do beneath a ceiling or an apex of pitched roof. 16.4.9~3

Other factors

(1) Factors affecting the sitting, number, etc. of the smoke detectors shall be considered carefully and the necessary measures shall be taken. Note: Among facts which can establish temporary or permanent conditions which have their effect on the sitting

of smoke detectors are various forms of overhead heating, air-cooled equipment, roof or ceiling of unusual shape, lofty buildings, staircases, canteen and restaurant, plant rooms, ambient air currents. 16.4~10

Audible and Visual Alarms

16.4.10.1 General (1) Inside a building, at least two sounders shall be installed. (2) In case of an automatic system, an additional sounder outside the building (preferably near five brigades access) shall be installed.

354

EBCS-10 1995

ETHIOPIAN BUilDING CODE STANDARD

SECTION 16: FIRE ALARM SYSTEM AND FIRE PUMPS 16.4.10.2 Audibility ofgeneral alarm (1) Alarm sounders shall satisfy the following requirments: a)' Their type, number and location shall be such that the alarm is distinct from the background noise in every part of the premises. 6) Their noise shall be quite distinct from any other sounders likely to be heard. c) Alarm sounders of the same kind on a particular installation shall produce a similar sound.

16.4.10.3 Restricted alarms (1) Where a general alarm is undesirable (e.g, department stores, entertainment places, hospitals), the alarm system shall be restricted to the provision of sounders out of the hearing of the public or patients. (2) The sounders should be supplemented by an adequate number of visual signals throughout . . the premises for staff recognition only and/or by discrete special alerting facilities.

16.4.10.4 Silencing switch (1) Silencing switches shall only be installed for transferring an alarm or fault warning to a supervisory sounders, and shall be so arranged as to put out of service the smallest practicable number of manual call points and detectors. (2) The operation of a silencing switch shall neither cancel the indications of the alarm or fault on any indicator concerned while an alarm or fault condition exists nor prevent the proper receipt of alarms or fault warnings on anycircuitother than those with which the silencing switch is associated.

16.4.10.5 Two-stage alarm (1) Where it is desired to distinguish between an alert and an evacuate signal, a two-stage alarm shall be used in which the ftrst type of signal indicates an alert and the second type indicates a need to evacuate the locality.

ETHIOPIAN BU1LD1NG CODE STANDARD

EBCS-10 1995

355


16.4.10.6 Visual alarm signals (l) In general, visual signals shall be used to supplement audible alarms.

(2) The operation of a sounder shall. not be prevented by a defect in a visual signal. or vice versa. (3) In situations where a normal type of alarm sounder may be ineffective, e.g. where the background noise is excessive or where the occupants are deaf, visual signals such as rotating beacon lamps shall be used in addition.

16.4.10.7 Audible alarms provided by public address equipment (1) Where public-addressequipment is used in stead of ensured that:

co~ntional

sounders, it shall be

a) alarm of fire is automatically transmitted over the public address system, taking priority and over-riding every other facility and circuit conditions of the public address system; b) other signals such meal-break, start and stop work, are not at any time broadcast by the public address equipment in a manner which can be confused with a fire alarm signals; c) during alarm conditions, all microphones are automatically disconnected, except one designated a "fire microphone" which is retained in circuit so that it can be used for announcements and instructions relating to the fire; d) the power supply, cabling,and wiring of the system shall comply with the requirements of this Section.

16.5

CABLES AND WIRING

16.5.1

Cables

16.5.1.1

General

(1) Cables shall have copper conductors and the cross-sectional area of the conductors shall be selected on the basis of the current consumption of the equipment used and the line length.

16.5.1.2

Insulation resistance

(1) The insulation resistance of the individual cable with respect to earth shall at least be 400.0Kohm.

356

EBCS-10 1995


-SECTION 16: FIRE ALARM SYSTEM AND FIRE PUMPS

16.5.1.3

Conductors cross section

(1) Conductors shall not be smaller than:

a) b) c) d)

1.5mm2 O.8mm 2 O.8mm2 O.5mm 2

for for for for

individual cables pulled into raceway;

individual cables laid into raceway;

an integral assembly of two or more cables;

an integral assembly of four or more cables.

16.5.1.4 Suitability (1) Cables shall be suitable for the purpose of the type listed in Annex B of Section 4. (2) Notwithstanding the requirements in (1) above, cables smaller than 2.5mm 2 installed in raceway shall be equipment-wire type.

16.5.2

Wiring Method

16.5.2.1 Installation (1) All conductors of a fire alarm system shall be;

a) installed in a metal raceway of the totally enclosed typl.'l;

b) incorporated in cable, having metal armour or sheath;

c) installed in rigid non-metallic conduit where embedded iuat least 50.0mm ofmansonary

or poured concrete, or installed underground.

16.5.2.2 Conductor in building 0/ combustible construction

~.. !"

(1) Conductors installed in buildings of combustible construction shall be permitted to be:

a) non-metallic sheathed cable; or .b) fire alarm and signal cable:


'.~

EBCS-10 1995

357


16.5.2.3 Segregation (I) The conductors shall be installed so as to be entirely exclusive to a fire alarm installation and the wiring of the alarm system shall be segregated from the wiring of any other circuits and shall not enter a fixture, raceway, box or enclosure occupied by other wiring, except as may be necessary for connection to: a) b) c) d)

the source of supply,

a signal,

an ancillary device,

a communication circuit.

16.5.2.4 Spacing and crossing (1) Fire-alarm wiring shall be spaced at least 50.0mm away from the circuits of any other

service. (2) Notwithstanding the requirements in (I) above, where crossings are unavoidable, a bridge of suitable non-combustible insulating material, at least 6.0mm thick, shall be securely fitted to maintain path in air of 50.0mm between circuits.

16.5.2.5 Highest voltage (l) All conductors contained in the same raceway or cable shall be insulated for the highest voltage in the raceway or cable.

16.5.2.6 Avoidance offlue-like opening (1) In order to reduce the likelihood of damage to fire-alarm cables by fire, main fire alarm Wiring shall avoid lift wells, staircase, and other flue-like opening.

16.5.2.7 Disruptive electricalinfluences (l) If necessary, special measures shall be taken to protect the fire-alarm networks against

disruptive electrical influences (electrical interferences) resulting from lightning strike, switching on high-power loads, electrical sparks of all types and electromagnetic waves.

358

EBCS·10 1995



16.5.2.8 Connection point (1) The number of connection points shall be as few as possible.

(2) Any necessary connection point must be soldered or established using another very reliable mechanical method.

16.'6

EQUIPMENT BONDING

16.6.1 Exposed Non-Current Carrying Metal Part (1) Exposed non-current-carrying metal parts of electrical equipment, including outlet boxes, conductors, raceway, and cabinets, shall be bonded to earth in accordance with Section 7.

16.6.2 Bonding Conductor (1) Where a non-metallic wiring system is used, a bonding conductor shall be incorporated in each cable and shall be sized in accordance with applicable Clauses of Section 7.

16.7 POWER SUPPLY SYSTEM 16.7.1 Operating Voltage (1) The operating voltage of a fire alarm system shall not exceed 230.0V nominal whether between conductors or to earth.

16.7.2 Sources of Power (1) Two mutually independent power sources shall be provided for powering a fire alarm system. The sources shall be: a) a general mains or an equivalent network, operated continually; and b) a rechargeable battery which is able to power the fire alarm system with no interruption in the events of a main's failure. (2) The power sources shall be permanently connected to the fire alarm system and it shall be ensured that failure of one power source does not result in failure of the other power source. Notes:

i) Only batteries that are suitable for stationary operation and trickle-charging must be used. ii) Where no mains supply is available, a primary battery may be used for powering fire alarm systems provided that a second similar battery in operational condition is held in reserve at all times.


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359

ELECTRICAL INSTALLATION OF BUILDINGS·

16.7.3

Current Supply

16.7.3.1

General

(1) The power supply from the electrical mains shall: a) be dimensioned such that unrestricted 6peration of the system and the altering facilities is guaranteed; and b) also be able to supply the trickle charge CUITent for the battery when the system is in normal operating condition.

16.7.3.2 Circuit connection (1) A fire-alarm system shall be supplied by its own separate circuit connected as close as practicable (without violating other Clauses of this Code) to: a) the load terminals on the main service disconnect; "b) the secondary terminal of the transformer, where transformer is necessary in order to supply a utilizatien voltage required by the fire alarm system; or . c) the terminals of a transfer switch, while a fire alarm system receives emergency power from an emergency power source which also supply other electrical equipment. .

16.7.3.3

Fusing

(1) A fire alarm's separate circuit shall be provided with its specially marked overcurrent device and disconnecting means which shall be clearly identified in a permanent, conspicuous and legible manner as a fire alarm system: and the disconnecting means shall be coloured red and . lockable in the "ON" position.

16.7.3.4

Charging facility

(1) The charging facility shall be dimensioned such that it if' capable of recharging a battery, the charge state of which has dropped to the cut-off voltage, automatically to 80% of its nominal voltage within a maximum period of 24 hours.

360

EBCS-10 1995



16.7.3.5

Interruption

(1) There shall be no possibility of the fire alarm system power supply being' interrupted as a

result of other plant facilities being switched off.

16.8

FIRE PUMPS

16.8.1 Conductors (1) Conductors shall be of copper and shall have their ampacityin accordance with Section 4 . and the requirements of the pump motor.

16.8.2 Wiring Method (1) All conductors of the fire pump equipment shall be: a) installed in a metal raceway of the totally enclosed type; . b) incorporated in metal raceway of the totally enclosed type; or c) incorporated in a cable, having a metal annour sheath of a type listed in Annex B of Section 4.

16.8.3

Consumers' Service for Fire Pumps

16.8.3.1

Box

(1) Where fire-pump equipment is connected to a consumers' service, a separate box for the fire

pump equipment shall be permitted.

16.8.3.2

Remote location

(1) A service box for the fire pump equipment shall be permitted to be located remote from other service box.

16.8.3.3 Labelling (1) A service box for fire pump equipment shall be labelled in a conspicuous, legible, and

permanent manner with the letter "FIRE PUMP".


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361


16.8.4

Protection

16.8.4.1

Overcurrent protection.'

(1) The rating or setting of the over-current protection for feeders and branch circuits shall be permitted to be selected to carry locked-rotor current of the motor(s) plus the rated current of associated equipment on the circuit. Note: Where the locked-rotor current is not marked on a motor, 600% of the rated current shall be considered to be the locked-rotor current.

16.8.4.2 .Short circuitprotection (1) The instantaneous short circuit characteristic shall be permitted to be selected or set at a minimum of the normal load current of the associated equipment on the circuit plus 12 times the full load current of the motor(s).

16.8.4.3 Overload and overheating protection (1) The branch circuit conductors and control conductors or equ~pment of a fire pump shall not require overload or overheating protection and shall be permitted to be protected by the motor branch-circuit over-current device(s).

16.8.4.4 Earth-fault circuit interrupter (I) Earth-fault protection shall not be installed in a fire pump circuit.

362

EBCS-10 1995


.

ANNEX

A (INFORMATIVE)

. FIRE ALARM SYSTEMS PRACTICAL EXAMPLES

Designations 1/1

:

1st digit - detector and alarm device group

FAP TS

2nd digit - detector or alarm device number in the detector and alarm device group : Fire alarm control and indicating panel : Transmission unit for fire alarm signals

.H

'

.

H

'" If

!

If

>IS

~

~

~

H

~

2 nd Floor

..

H

H

w

'"

'"

!.

Y,

!.

~

~,

H

1,t Floor

~

.....

r-e

H

?/

In

s

H

'"

1nI

UE

'/////,1 1111

'"

, .. O....111M01t

BUl~

..,

Ground Floor

~ •

'//.

Cellar

Figure A.1 Example - Automatic If=

ti~e

alarm system

:=---. '''~' 1/'

~ lit....'"

,;,[

c- '"

"'7J

~lIl

1/)['"

l/lB

Figure A.2 Example device

! '"

.~

•

UE

E1~1I

.,

''''n~_

"Melll"!1

Automatic tire alarm systems with non-automatic tire alarm


EBCS-10 1995

363


~

3/3

6 3/~

~III

3Il '

~

3ilor:

311

r

3112,

311

, 3("

~'

~IS

6 ylG

1 319

311

J

. -

10

r

3IS

Hall

M~,," ,

I/GnUS

>

A'D4.

ll¥ ./

I liG

211

L 1/1

/,fA

,;.

111 ~

",,/,

1/9 {}

61(l

,

0';'

IIIUO

Block circuit diagram,

I'

,~

RIUJ

1I~

~S

llf

I

1

11101, MA'

tf§

,

fkt

,

R~ m

I

~

~

t--------..,.. E- - ' II

---------

1/1

-

-

-

-

-

-

-

:UI

I

IWI '"

11,11

r

rwt ~I

(m"nCl

rn

Hlioior .In"Ulllu

,

- - -:.--r ...--: FHIOllPlrlRl""

,IFWI

-

--.11°,

,I

D.,.,"...'

"pp'Neil "lila

-

-1fj IIi... 'l/M

-Q

tI

11001"

101

lin -11,14",II',

el."n kwhCl'.' tfAAI

Jil~

"If

fl,n

Aus.

I

uE :

PIlIU,1 palnellPT. II" .1.,ntJ' ..dl

Mlln' caM,eligrt

I6A

Figure A.3 Installation plant of a fire alarm system with block circuit diagram

364

EBCS-10 1995


ANNEX

B (INFORMATIVE)

CIRCUIT DESIGN

B.l MANUAL AND AUTOMATIC B.l.l

CA~L

POINT CIRCUITS

Introduction

Whilst there are but two basic call point control circuits, i.e. 'open circuit' and 'closed circuit', simple definition of each can be misleading because, in practice, there are employed numerous variations and combinations of each circuit. The type of circuit to be used should be determined by careful consideration of the functions required from the fire alarm system in the particular building concerned, taking into account simplicity, reliability, liability to damage, operational supervision, cost, environment and such other relevant factors. It is unwise to assume, in general, that one type of circuit is better than another. Four simplified but typical, circuits are given below. Alarm and fault-sensing units may be relays, solid-state circuits or similar devices; call points may have mechanical contacts, solid state circuits, variable-resistance devices, etc. It should be appreciated that many other circuit arrangements are possible and the following circuits should in no way be considered other than for the purpose of illustration.

//

B.l.2 Circuit 1 - Open circuit

Alarm-sensing unit

/ .

Di--"--·----'----·

o

r--I /1

'---1

supply

- I!

Figure B.l Open circuit

)/

::J

Open Circuit Call Point


EBCS-10 1995

365


Current flows when the call point contacts are closed, causing the alarm-sensing unit to operate and initiate an alarm signal. A broken connection/conductor will prevent a call point beyond the break from operating the alarm-sensing unit. A short-circuit between conductors will cause the alarm-sensing unit to operate, producing an alarm signal. In this circuit, the alarm-sensing unit could be the alarm sounder.

B.l.3 Circuit 2 - Closed circuit

Alarm-Sensing Unit 0--

I

supply

o

0

I

0

,I

I

Closed circuit call point Figure B. 2 Closed circuit

. Current is normally flowing through the conductors and call points; the alarm-sensing unit is hand operated. When a call point's contacts are opened, the current is interrupted allowing the alarm-sensing unit to release and initiate an alarm signal. A broken connection/conductor interrupts the current to the alarm-sensing unit, initiating an alarm signal.

366

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A short-circuit between conductors will allow the current to by-pass call points ,beyond the short-circuit; thus, a call point beyond the short-circuit cannot interrupt the current and cannot, therefore, initiate an alarm signal. B.1.4 Circuit 3 - Combination of open and closed circuits, Type A High-current ~ Limiting resistor Sensing Unit(alarm)

supply

o

--+--

1\/1

I

Low-current L Open circuit call point sensing unit (fault)

Figure B.3

Combination of open and closed circuits, Type A

The conductors are closed-circuit connected; a resistor limits the current through two sensing units to a value sufficient to hold operated the low-current (faults) sensing unit, but insufficient to operate the high-current (alarm) sensing unit Open circuit call points are connected across the conductors. Operation of a call point allows the current to by-pass the resistor. The resultant increase in current operating the high-current (alarm) sensing unit which initiates an alarm signal. A broken connection/conductor will interrupt the current, releasing the low-current (fault) sensing unit:which initiates a fault signal. A short-circuit between conductors by-passes the resistor, the resultant increase in current operates the high-current (alarm) sensing unit, which initiates an alarm signal.


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ELECTRICAL INSTALLATiON OF BUilDINGS

B.l.S . Circuit -I - Combination open and closed circuits, Type B Medium-current Sensing unit (alarm>/ Open circuit call point ~

I

I

-I 0

,0

,~---

Supply

o

i

I Low-current sensing unit (fault)

Limiting resistor

call· point resistor

Figure B.4 Combination open and closed cireuits, Type B

The conductors are "closed circuit" connected, the open-circuit call points being wired in series, their contacts being bridged by resistors. The values of the call point resistors and of the limiting resistor are carefully chosen to ensure that the correct current flows in the circuit during the various conditions of fault and alarm. Under normal conditions, the current flowing in the circuit is sufficient to hold the low-current (fault) sensing unit operational, but is insufficient to operate either the medium- or the high current alarm or fault-sensing units. Operation of a call point by-passes its call point resistor. The resultant increase in current is . sufficient to operate the medium-current alarm-sensing unit, which initiates an alarm signal, but is insufficient to operate the high-current fault-sensing unit. A broken connection/conductor will interrupt the current, releasing the low-current fault-sensing unit which initiates a fault signal. A short-circuit between conductors by-passes the limiting resistor. The resultant increase in current is sufficient to operate both the medium-current alarm and the high-current fault-sensing units. The former's attempt to initiate an alarm signal is overridden by the latter and a fault signal is initiated. Study of the above circuits will indicate that each circuit has advantages and disadvantages. Some of these are outlined in Clause B.2.

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EBCS-10 1995

ETHIOPIAN BUILDII\lG CODE STANDARD

SECTIO~I

16: FIRE ALARM SYSTEM AND FIRE PUMPS

B.2

ADVANTAGESAl~DISADVANTAGESOFVARIOUSCALLPOINTCIRCUITS

b.2.1

Circuit 1

a) Advantages i) This is a simple and reliable circuit. ii) No current is consumed on stand-by; therefore, a battery and charger of moderate size and cost may be used. iii) A broken connection or conductor will not result in a false alarm, b) Disadvantages There will be no indication of a break in the circuit which may make some parts of the system inoperative. ii) A short-circuit between conductors will produce a false alarm. i)

iii) The call points are not monitored. B.2.2 Circuit 2

a) Advantages . i) This is a simple and reliable circuit.

ii) The call points are monitored.

iii) The contacts and connections are monitored.

b) Disadvantages i)

Current is consumed on stand-by; therefore, the size and cost of the battery and charger will be increased. ii) There will be no indication of a short-circuit between conductors which may make some parts of the system inoperative. iii) A broken connection or conductor will cause false alarm.


EBCS-101995

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B.2.3 Circuit 3 Type A a) Advantages' i) The conductors are monitored. ii) An open circuit of a connection or a conductor will produce afault signal; not a false

alarm. b) Disadvantages

i) Current is consumed on stand-by.

ii) A short circuit between conductors will cause a false alarm.

iii) The call points are not monitored.

B.2.4 Circuit 4 Type B

a) Advantages

i) The conductors are monitored. ii) An open circuit of a connection or a conductor will produce a fault signal, not a false alarm. iii) A short-circuit between conductors will produce efault signal, not a false alarm. b) Disadvantages

i) Current is consumed on stand-by. ii) The selection of values of call-point resistors and limiting resistors is critical. A number of call points operated together may result in a fault signal instead of an .alarm signal. iii) There is a need for introduction of additional and complex sensing equipment.

370 . EBCS-10 1995

. ETHIOPiAN BUILDING CODE STANDARD

SECTION

17

SIGNS AND OUTLINE LIGHTING

17.1

SCOPE

(1) This provisions of this Section apply to the installation of signs and outline lighting wherein the source of light w:e: a) b) c) d)

incandescent lamps,

fluorescent lamps,

high-voltage luminous discharge tubes including neon tubes, and

high intensity discharge lamps.

Note:

The word "sign", when used throughout this Section, includes those of the through-wall type.:

17.2



17.3

a) IEE:1970

The Institute of Electrical Engineers, Regulation for the Electrical Equipment of Buildings, Fourteenth Edition (1966), Incorporating Amendments.

b) C22,1: 1990

Canadian Electrical Code, Part 1, Safety Standard for Electrical Installation, Sixteenth Edition


17.3.1 Construction (1) All signs and outline lighting apparatus, accessories, and fittings manufactured wholly or in part in the field shall comply with the relevant requirements of:


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a) this Code; and b) the applicable international standards, if any, except so far as these requirements may be modified by this Code.

17.3.2 Disconnecting Means (1) Each outline lighting installation and each sign other than the portable type shall be provided with a disconnecting means which shall: a) open all unearthed conductors;

b) be suitable for condition of installation such as exposure to weather; and

c) be integral with the sign or outline lighting.

17.3.3 Rating of Disconnecting Means and Control Devices (1) Switches, flashers, and similar devices breaking inductive loads shall be either of a type approved for the purpose or have a current rating of not less than twice the current rating of the loads.

17.3.4 Thermal Protection (1) Ballasts of the thermally-protected type shall be required for all signs and outline lighting which employ fluorescent lamps except where the ballasts are of the simple reactance type.

17.3.5 Branch Circuit Capacity (1) Circuits shall be arranged so that the load imposed by lamps and associated gears shall not exceed 80% of the branch circuit overcurrent protection.

17.3.6 Location (1) Signs and outline lighting shall be located so that all the following requirement are met: a) Any person working thereon is not likely to come into contact with overhead conductors. b) No part of the sign or its support will interfere with normal work operations performed on electrical and communication utility lines. c) No part of the sign or its support is in such proximity to overhead conductors as to constitute a hazard.

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EBCS-10 1995


SECTION 17: SIGNS AND OUTLINE LIGHTING

d) Unless mechanical protection is provided to prevent persons or vehicles from coming into contact with the electrical components of the sign, no part of the sign, other than its support, shall be located within 202m above grade. 17.3.7 Bonding (1) All conductive non-current-carrying parts of the lighting installation shall be bonded to earth in accordance with the requirements of Section 7 except for conductive parts of letters attached to the building and illuminated from the rear. 17.3.8 Protection of Sign Leads (l) Sign leads which pass through the walls or partitions of the sign structure shall be protected by non-combustible, moisture-absorption resisting bushings.

17.3.9 Installation of Conductors (l) Conductors for sign and outlying lighting shall be installed in accordance with the requirement of Section 8.

17.3.10 Fuseholders and Flashers (l) Fuseholder, flashers, etc. shall be enclosed in metal and shallbe accessible without the necessity of removing obstructions or, otherwise, dismantling the sign.

17.4

IDGH-VOLTAGE LUMINOUSDISCHARGE TUBE SIGNSANDOUTLINE LIGHTING

17.4.1 Enclosure

17.4.1.1

Cleneral

(l) Enclosure for transformers, switches, timers, relays, sequencing units and other similar devices shall be of metal or of heat and moisture resistant, non-combustible material.


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ELECTRICAL lNSTALLATION OF BUILDINGS . .. .

.~

.

.

.

17.4.1.2 Construction (1) The enclosure shall be constructed to prevent the emission of flames or any burning or ignited material.

17.4.1.3

Ventilation

(1) Openings for ventilation shal! be-arranged to comply with the requirement of 17.4.1.2 shall at least be lOO.Omm from live parts. 17.4.1.4

and

Thickness

(1) Metal enclosures shall not be less than O.8mm thick and at the point where it is intended

that the supply connections be made, the enclosure shall be of not. less than 1.6mm in thickness. 17.4.1.5

Marking

(1) Each enclosure housing a transformer shall be marked in accordance with the requirements

of Clause 2.4.6.

1704.2 Proteetlon of Uninsnlated Part (I) Doors or covers accessible to the general public and which give access to uninsulatedparts

of indoor signs or outline lighting shall either be provided with interlock switches which, on the opening of the doors or covers, disconnect the primary circuit or shall be fastened so that the use of other than ordinary tools will be necessary to open them.

1704.3 Transformers 17.4.3.1

Secondary voltage

.(1) The rated secondary open-circuit voltage of transformers shall not exceed 15.0kV, except as in (2) below. (2) In end-earthed transformers, rated secondary open-circuit voltage shall not exceed 7.5kV.

.

I: ....,. .

374

EBCS- to 1995


SECTION 11: SIGNS AND OUTLINE LIGHTING

17.4.3.2.

Open core-and-coil type transformer

(1) Open core-and-coil type transformers shall only be used indoor.

17.4.3.3 Transformers used outdoors (1) Transformers used outdoor shall be of the weather-proof type or shall be enclosed in the sign body or in a separate weather-proof box.

17.4.3.4 Installation (1) Transformers shall be installed in such location that they are accessible and capable of being removed and replaced. (2) They shall be supported by attachment to the enclosure in which they are housed by at least two studs or bolts.

17.4.3.5 Overcurrent protection (l) Each transformer shall be protected by an overcurrent device except that two or more transformers may be protected by one ove-current device if their combined load does not exceed 12.0A.

17.4.4 High-Voltage Wiring Methods

17.4.4.1

Conductor installation

(1) High-voltage conductors shall be installed in: a) b) c) d) e)

transformer enclosure,

sign enclosure,

flexible metal conduit,

rigid conduit, or

other acceptable type of raceways except for surface raceways.


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ELECTRICAL INSTALLATION OFBUILDINGS

17.4.4.2

Conductors run

(1) High-voltage conductors may be run from the ends of gas tubes to the earthed midpoint of transformers which have terminals at the midpoint.

17.4.4.3

Bends

(1) There shall be no bends in high-voltage conductors.

17.4.4.4

Type of conductors

(1) All high voltage conductors installed inside metal sign enclosures shall be of the luminous-tube-sign type cables.

17.4.4.5

Length of cable from transformers

(1) In a metalic raceway and in a non-metallic raceway, cables not more than a total of 6.0m and 16.0m, respectively, shall be run from transformer to other parts of the sign.

17.4.4.6

Connection of conductors

(1) Connection of high-voltage conductors to neon tubing outside the building or structure shall be made by means of one of the following.

a) an electrode receptacle; b) a direct connection in the neon tubing outside the building or structure wall provided that not more than 1.0m of high-voltage wiring extends beyond the end of the raceway; c) any other acceptable methods. Note:

376

The connection in (b) shall be electrically secure and provided with acceptable wrapping of insulating tape.

EBCS-10 1995


· SECTION

18

LIFTS, ESCALATORS· AND SIMILAR EQUIP:MENT

18.1

SCOPE

(l) This Section applies to the installation of electrical equipment for passenger, good's or dual-purpose elevators (lifts), including dumbwaiters, escalators, movmg walks, freight platform lifts, and elevating devices for the handicapped.

18.2



18.3 'I

a) C 22.1: 1990

Canadian Electrical Code Part 1, Safety Standard for Electrical Installations, Sixteenth Edition.

b) NFPA 701NEC: 1986

National Fire Protection Association!American National Electrical Code, 1987 Edition.

GENERAL

18.3.1 Voltage Limitation (1) The nominal voltage used for lift operating control and signalling circuits, operating

equipment, driving machine motors, machine brakes, and motor generator sets shall not exceed the following: a) 380.0V for operating control and signalling circuits and related equipment, including door operator motors. b) 750.0V for driving motors, machine brakes, and motor-generator sets.


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Exemption:

Higher voltages shall be permitted for driving motors of motor generator sets.

18.3.2 Live Parts Enclosed (1) All live parts of electric apparatus in hoistways, at landings or in or on the cars of lights and dumbwaiters or in the well-ways or the landing of escalators, or moving walks shall be enclosed to protect against accidental contact.

18.4

CONDUCTORS

18.4.1 Installation of Conductors

18.4.1.1

Hoistway door interlocking wiring

(1) The conductors to the hoistway door interlocks from the hoistway riser shall be flame-retardant and suitable for temperature of not less than 200°C.

18.4.1.2

Travelling cables

(1) Travelling cables used as flexible connections between the lift car and the raceway shall be of the types of lift cables or other approved type.

18.4.1.3

Other wiring

(1) All conductors in raceways, in or on the cars of lifts and dumbwaiters, in the well-ways of escalators and moving walks, and in the machine room of lifts, escalators, and moving walks shall have flame-retardant insulation.

18.4.1.4 lnsulation rating (1) All conductors shall have an insulation voltage rating equal to at least the maximum nominal circuit voltage rating of any conductor within the enclosure, cable or raceway.

18.4.2 Minimum Size of Conductors (1) The minimum size of conductors used for lifts, dumbwaiters, escalators, and moving walk wiring, other than conductors that forms an integral part of control equipment, shall be as follow:

378

EBCS-10 1995


I

SECTION 18: LIFTS, ESCALATORS AND SIMILAR EQUIPMENT

a) for lighting circuits, I.Smm"; and

b) for operating control and signalling circuits, 0.5mm2 •

. 18.4.3 Motor Circuit Conductors

(1) Conductors supplying lifts, dumbwaiters, escalator, or moving walk motors shall have an ampacity of: (a) (b)

18.5

if supplying single motor, not less than 150% of the motor full-load current rating. if supplying two or more motors, not less than 125% of the nameplate current rating of the highest rated motor in the group plus the sum of the nameplate current ratings of the remainder of the motors in the group.

WIRING

18.5.1 Wiring Methods

18.5.1.1 In hoistway, machine rooms, and escalator wellways (1) Conductors located in hoistway, machine rooms and escalator well-ways, except travelling cables, shall be installed in rigid metal conduit, electrical metallic tubing, or metal wireways, except that flexible metal conduit or armoured cable shall be permitted only if not subjected to mechanical damage. Exemption: Mineral-insulated cable or aluminium-sheathed cable may be used if located so that there is no liability

of damage to the sheath.

18.5.1.2 On cars (1) Conductors on lift and dumbwaiter cars shall be run in rigid metal conduit, electrical metallic tubing, or wireways, except that: a) short runs of flexible metal conduit or armoured cable may be used where they are securely fastened in place and not exposed to oil or grease; b) hard usage flexible cord shall be permitted to be used between fixed wiring on the car and switching or sensing devices on the door or gate, and. between the fixed car top inspection light and an extension light controlled by the SlUlle switch, provided it is securely fastened and so located as to not be subject to mechanical injury;


EBCS-10 1995

379 .


c) mineral-insulated cable.or aluminium-sheathed cable may be used iflocated so that there is no liability or damage to the sheath.

18.5.2

Branch Circuits for Auxiliary Systems

18.5.2.1

Car lighting and accessories

(1) In passenger lifts, at least one branch circuit shall be provided solely for the lighting and accessories on each car.

18.5.2.2

Air conditioning

(1) Where air conditioning units are installed on the car, they shall be supplied by separate branch circuits.

18.5.2.3

Protection device location

(1) The overcurrent device protecting each branch circuit shall be located in the machine room.

18.6

INSTALLATION OF CONDUCTORS

18.6.1 Number of Conductors in Raceway (1) The sum of the cross-sectional area of the operating and control circuit conductors in raceways shall not exceed 40% the interior cross-sectional area of the raceway.

18.6.2 Supports (1) Supports for cables or raceways in a hoistway or in an escalator or moving walkways shall be securely fastened to the guide rail or to hoistway well-way construction.

18.6.3 Different Systems in One Raceway or Travelling Cable (1) Conductors for operating, control, power, signalling and lighting circuits of 600.0V or less shall be permitted to be run in the same travelling cable or raceway system if all conductors are insulated for maximum voltage found in the cables or raceway system and if all live parts of the equipment are insulated from earth for the maximum voltage.

380

EBCS-10 1995



(2) Such travelling cable or raceway in (1) above shall be permitted to include shielded conductors and/or one or more coaxial cable if such conductors are insulated for the maximum voltage found in cable or raceway system. Conductors shall be pennitted to be covered with suitable shielding for telephone, audio, video or higher frequency communication circuits.

18.6.4 Wiring in Hoistway (1) Main feeders for supplying power to lifts and dumbwaiters shall be installed outside the hoistway (hoist shaft). Note:

Only wiring, raceways, and cables that are or form part of lift or dumbwaiter installation, including wiring for signals, for communication with the car, for lighting, heating, air conditioning and ventilating the car, for fire detecting systems, for pit pumps, and for heating and lighting the hoistway, shall be permitted inside the hoistway.

18.6.5 Electric Equipment in Garages and Similar Occupancies (1) Electric equipment and wiring used for lifts, dumbwaiters, escalators, and moving walks in garages shall comply with the requirements of Section 12 (Class I locations). Wiring and equipment located on the underside of the car platform shall be considered as being located in the hazardous area.

18.6.6 Sidewalk Lifts (1) Sidewalk lifts with sidewalk doors located exterior to the building shall have all electrical wiring in metallic tubing and all electrical outlets, switches, junction boxes and fittings shall be weather-proof.

18.7

TRAVELLING CABLES

18.7.1 Suspension (1) Travelling cables shall be so suspended at the car and hoistway's ends as to reduce the strain on the individual copper conductors to a minimum and shall be supported by one of the following means: a) by its steel supporting members;

b) by looping the cable around supports for unsupported lengths less than 30.0m;


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c) by suspending from the supports by means that automatically tightens around the cable when tension is increased for unsupported lengths upto 60.0m.

18.7.2 Hazardous (Classified) Location (1) In hazardous (classified) locations, travelling cables shall be of a type approved for hazardous (classified) locations and shall be secured to explosion-proof cabinets.

18.7.3 Protection Against Damage (1) Travelling cable supports shall be so located as to reduce to a minimum the possibility of damage due to the cable coming into contact with the hoistway construction or equipment in the hoistway; and where necessary, suitable guards shall be provided to protect the cable against damage.

18.7.4 Installation (1) Travelling cable shall be permitted to be run without the use of raceway or conduit for a distance not exceeding 1.8m from the first point of support on the lift car or hoistway wall provided the conductors are grouped together and tapped or corded or in the original sheath. (2) Travelling cables shall be permitted to be continued to lift control panels and to lift car and machine room connections as fixed wiring provided they are suitably supported and protected from damage.

18.8

DISCONNECTING MEANS AND CONTROL

18.8.1 General (1) Lifts, dumbwaiters, escalators, and moving walks shall have a single means for disconnecting all unearthed main power supply conductors for each unit.

(2) Where multiple driving machines are connected to a single lift, escalator, moving walk or pumping unit, there shall be one disconnecting means to disconnect the motor(s) and control devices.

382

EBCS-10 1995



(3) Where there is more than one driving machine in a machine room, disconnecting means shall be number-marked to correspond to the number-mark of the driving machine which they control.

18.8.2 Type (1) The disconnecting means shall be an enclosed, externally operable, fused motor circuit switch or circuit breaker to be locked in the open position.

(2) No provision shall be made to close the disconnecting means in (1) above from any other part of the premises; nor shall circuit breakers be opened automatically by a fire alarm system.

18.8.3 Location (I) Disconnecting means shall be located where they are readily accessible to qualified persons;

18.8.4

Phase Protection

18.8.4.1

Electric lifts

(1) Lifts. dsivenby polyphase alternating current shall be provided with a means to prevent starting ofthe lift when: a) the phase rotation is in the wrong direction, or

b) there is a failure in any phase.

18.8~4.2

Hydraulic lifts

(1) Hydraulic lifts powered by a polyphase alternating current motor shall be provided with the means to prevent overheating of the drive system (pump and motor) due to phase-rotation reversals or failure.

18.9

OVERCURRENT PROTECTION

18.9.1 Control and Operating Circuits (1) Control and operating circuits and signalling circuitsshall be protected against overcurrent . in accordance with the requirements of the relevant Clauses of Section 9.

ETHIOPIAN BUlLDING CODE STANDARD

EBCS-10 1995383

ELECTRICAL INSTALLATION OF BUILDINGS ---------", . _ - - - ' - , - - - - - - -

18.9.2

Motors

18.9.2.1

Non-continuous duty

(1) Duty on lift and dumbwaiter driving-machine motors and driving motors of motor-generators - used with generator field control shall be classed as non-continuous. Such motors shall be' protected against overcurrent in accordance with applicable Clauses of Section 11.

18.9.2.2

Continuous duty

(1) Duty on escalators and moving-walk driving motors shall be classed as continuous. Such motors shall be protected against overcurrent in accordance with applicable Clauses of Section 11.

18.10 MACHINE ROOM 18.10.1

Guarding Equipment

(1) Lifts, dumbwaiters, escalators, and moving walk driving machines, motor-generator sets, motor controllers, and disconnecting means shall be installed in a room or enclosure set aside for that purpose. (2) The room or the enclosure in (1) above shall be secured against unauthorized access.

18.10.2

Clearance around Control Panels and Disconnecting Means

(1) Sufficient clear working space shall be provided around control panels and disconnecting means to provide safe and convenient access to all live parts of the equipment necessary for maintenance and adjustment.

18.11 EARTmNG 18.11.1

Metal Raceway Attached to Cars

(l) Metal raceways attached to lift cars shall be bonded to earthed metal parts of the car with which they come into contact.

384

EBCS-10 1995



18.11.2

Electric Lifts

(1) For electric lifts, the frames of all motors, lift machines, controllers, and the metal enclosures of all electric devices in or on the car or in the hoistway shall be earthed in accordance with Section 7.

18.11.3

Non-Electric Lifts

(1) For lifts other than electric and having any electric conductors attached to the car, the metal frame of the car, where normally accessible to persons, shall be earthed in accordance with Section 7. 18.11.4

Method of Bonding

18.11.4.1 Equipment (I) Equipment mounted on members of an earthed structural metal frame of a building shall be deemed to be bonded to earth.

18.11.4.2 Metal car frame supported by cables (1) Metal car frames supported by metal hoisting cables attached to or running over metal sheaves or drums of lift machines and affording metal-to-metal contact therewith shall be deemed to be bonded to earth when the machine is bonded to earth in accordance with Section 7.

18.12 OVERSPEED 18.12.1

Overspeed Protection

(1) Under overhauling load conditions, a means shall be provided on the load side of each lift power disconnecting means to prevent the lift from attaining a speed equal to the governor tripping speed or a speed in excess of,125% of the lift rated speed, whichever is smaller.

(2) Overhauling load conditions shall include all loads upto rated lift loads for goods lifts and all loads upto 125% for the rated lift loads for passenger lifts.

ETHIOPIAN BUILDING CODE STANDAR.D

EBCS-10 1995

385


18.12.2

Motor-Generator Overspeed Device

(1) Motor generators driven by direct current motors and used to supply direct current for the operation of lift machine motors shall be provided with speed-limiting devices that will prevent the lift from attaining, at any time, a speed of more than 125% of its rated speed.

18.13

EMERGENCY POWER

18.13.1

Supply

(1) A lift shall be permitted to operate from an emergency power supply in the event of normal supply failure, provided the lift operates on such emergency power in accordance with the emergency power system requirementsofa recognized international safety code for lifts.

18.13.2

Disconnection

(1) The disconnecting means shall disconnect the emergency power service from the normal power service.

18.13.3

Hydraulic Lifts Disconnecting Means

(1) In the case of hydraulic lifts where emergency power-is supplied from a second source for lowering the car only, thedisconnecting means shall be provided with an auxiliary contact that is positively opened mechanically, the opening not being solely dependent on springs, and connected in the control circuit to prevent movement of the car when the disconnecting means is open.

18.14

MACHINE ROOMS AND HOISTWAY PITS LIGHTING AND AUXILIARY SYSTEMS

18.14.1

Machine Room

18.14.1.1 Lighting

(1) Permanent provision of adequate artificial light shall be made in machine rooms of power lifts.

386

EBCS-10 1995



18.14.1;2 Illumination level (I) Illumination shall he not less than lOO.Olx at floor level.

18.14.•1.3 Lighting swit.eh (I) The machine room lighting switch shall be within easy reach of the entrance to the machine room.

18.14.1.4 Socket outlet (1) At least one duplex (twin) socket outlet connected to 16.0A 'branch circuit supplying no

other socket outlets shall be installed in the machine room.

18.14.2

Hoist Pits

18.14.2.1 Luminaire (l)One or more permanent luminaireequipped with.aguard of metal, safety glass.or suitable 'plastic material shall beprovided in all .pits,

18.14.2.2 Illumination level

The luminaires shall provide an illuminations level of at least 100.01x at the pit floor,

18.14.2.3 Lighting switch (1) A light switch shall be provided and shall be located so as to be accessible from the pit

access door.

18.14.2.4 Socket outlet (I) At least one twin socket outletconnected toa 16,OAbranch circuit supplying no other

socket outlet shall be installed in each pit.


EBCS-101995387

\SECTION

19

THEATRE INSTALLATION

19.1

SCOPE

(1) This Section applies to electrical equipment and their installations in buildings or parts' of a building designed, intended, or used for drama, opera, motion picture, or other shows.

19.2


(1) The following reference contains provisions which, through reference in this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings.

a) C22.1:1990

19.3

Canadian Electrical Code, Part 1, Safety Standard for Electrical Installation, Sixteenth Edition.

WIRING METHOD

(1) Wiring in stage and stage wing areas, orchestra pits, and projection booths shall be in rigid metal conduit, armoured cable, lead-sheathed armoured cable, or aluminium-sheathed cable except that: a) other wiring methods shall be permitted for temporary work,and

b) flexible cord or cable shall be permitted in accordance with other Clauses in this Section.

(2) Surface raceways shall not be used on the stage side of the proscenium wall, (3) Wiring in areas other than those listed in (1) above shall be in accordance with the requirements of the appropriate Sections of this Code. (4) Circuits for aisle lights located under seats may supply 30 outlets provided that the size of lamp which can. be used with each outlet is limited by barriers or the equivalent to 25.0W or less.

388

EBCS-10 1995


SECTION 19: THEATRE INSTALLATION

19.4

FIXED STAGE SWITCHBOARD

(1) Stage switchboard shall be: a) of the dead-front type, and b) protected above with a suitable metal guard or hood extending the full length of the board and completely covering the space between the wall and the board to protect the latter from falling objects. (2) Where a stage switchboard has exposed live parts on the back of the board, it shall be enclosed by the walls of the building, by wire mesh grills, or by other acceptable methods. (3) The entrance to the enclosures shall have a self-closing door. (4) Switches shall be of the enclosed type and externally operated. (5) Pilot lamp on switchboard shall be: (a) (b) (c)

installed within every switchboard enclosure, connected to the circuit supplying the ·switchboard so that the opening of the master switch does not cut off the supply to the lamp, and on an independent circuit protected by an overcurrent device rated or set at not more than 15.0A.

19.4.1 Fuses (1) Fuses on switchboards shall be:

a) of either the plug or cartridge type, and

b) provided with enclosures in addition to the switchboard enclosure.

19.4.2 Overcurrent Protection (1) All circuits leaving the switchboard shall have an overcurrent protection device connected in each unearthed conductor.


EBCS-10 1995

389

ELECTRICALINSTAU.ATlbNOF :SUILD'ING$

19.4.3 Dimmers (I) Dimmersshall be connected so as to' be deadwhen their respectivecircuit switches ate open. (2) Dimmers which do not 'open the circuit maybeconnected :lh earthedneutralconductor. (3) The terminals Of dimmers 'shallbe enclosed, (4) Dimmer faceplates shall be arranged so thataccidentalcontactcannot readilybemadewith the faceplate contacts.

19.4.4 Control of Stage and Gallery Pockets (I) Stageandgallerypockets shall be controlled from the switchboard. 19;4.5 Conductors (1) Stage switchboardsequipped with resistive- ortransformed-type 'aimmerswit~hesshanbe wifed With conductors having insulationsuitable for the temperaturegenera:ted therein; 'bot in no case shall the design temperature 'be less than 125°C. (2) The conductors in (I) above shall have an ampacityof not less than that ofthe switch or overcurrent device to which they are connected. (3) Holes in the metal enclosure through which conductors pass shall be bushed. (4) Thestrands Of theconductor shall be soldered together before they ate fastenedundera clamporbinding screw. (5) Where a conductor of IO;Omm 2 or of a largersizeisconrrectedto a terminal: a) it shall be soldered into a lug, or b)a solderless connector shall be used.

390

ESCS-10 1995


Sf;CTlQN 1~: THEATRE- !N$TALL,ATI,ON

19.5

J,?QRTi\BLE SWITCHBQARJ) ON

~TAGE

19.5.1 CQnstrll.ction of Portable Switchboards (1) Portable switchboards shall be placed within enclosure of substantial construction; but they may be arranged SO that the enclosure is open during, operation,

(2) There shall be no live parts exposed within the enclosure except those on dimmer faceplates, 19.5.2 Supply for Portable Swltehboard (1) Portable. switchboards shall be supplied by Il1eaJ;1S of flexible cord or cable of extra-hard usage type terminating within the switchboard enclosure in aJ;1 externally operated, enclosed, fused master switch.

(2) The. master switch in (1) above shall be arranged so as to cut off current from all apparatus within the enclosure except the pilot li~ht. (3) The flexible cord or cable shall have sufficient amapcity to carry the total load current of the switchboard. (4) The ampere-rating of the fuses of the master switch shall not be greater than the. total load current of the switchboard.

19.6

FIXED ST i\GE EQUIPMENT

19.(j.l Footlights (1) Where footlights are wired in rigid metal conduit or electrical metallic tubing, every lampholder shall be installed in an individual outlet box, (2) Where footlights are not wired in rigid metal conduit or electrical metallic tubing, the wiring shall be installed in a metal trough.

19;(i.2 Metalwork (I) The metalwork for footlights, borders, proscenium sidelights, and strips shall not be lesr than O.8mm thick.


EBCS-10 1995

391

ELECTRICAL INSTALLATION OF BUIl.DINGS

(2) The metalwork for bunches and portable strips shall be not less than O.5mm thick.

19.6.3 Clearance at Terminals (1) The terminals of lampholders shall be separated from the "metal of the trough by at least 13.0mm.

19.6.4 Mechanical Protection (1) Borders, proscenium sidelights, and strips shall be constructed so that the flanges of the reflectors or other suitable guards protect the lamps from mechanical injury and from accidental contact with scenery or other combustible material.

19.6.5 Suspended Fixtures (l) Borders and strips shall be so suspended as to be electrically and mechanically safe.

19.6.6 Connections at Lampholders (1) Conductors shall be soldered to the terminals of lampholders unless other suitable means are providedto obtain positive and reliable connection under severe vibration.

19.6.7 Ventilation for Mogul Lampholers (1) Where the lighting device are equipped with mogullampholders, the lighting devices shall be constructed with double walls and with adequate ventilation between the walls.

19.6.8 Conductor Insulation for Field-Assembled Fixtures (I) Foot, border, proscenium, and portable striplight fixtures assembled in the field shall be wired with conductors having insulation suitable for the temperature at which the conductors will be operated; but in no case shall the design temperature be less than 125°C.

19.6.9 Branch Circuit Overcurrent Protection (1) Branch circuits for footlights, border lights, and proscenium sidelights shall have overcurrent protection in accordance with 15.3.1.4.

392

EBCS-10 1995



19.6~10

Pendant Lights Rated More Than 100.0W

(1) Where, a pendent lighting device contains a lamp or group of lamps of more than lOO.OW capacity, it shall be provided with a guard of not more than 13.0mm mesh so arranged as to prevent damage from falling glass.

19.6.11 Cables for Border Lights (1) Flexible cord or cable for border lights shall be of extra-hard-usage type. (2) The flexible cord or cable shall be fed from points on the grid iron or from other acceptable overhead points; but they shall not be fed from side walls. (3) The flexible cord or cable shall be arranged so that strain is taken from clamps and binding screws. (4) Where the flexible cord or cable passes through a metal or wooden enclosure, a metal bushing shall be provided to protect the cord. (5) Terminals or binding posts to which flexible cords or cables are connected inside the switchboard enclosure shall be located so as to permit convenient access to them.

19.6.12

Wiring to Arc Pockets

(1) Where the wiring to arc pockets is in rigid metal conduit or electrical metallic tubing, the. end of the conduit or tubing shall be exposed at a point approximately 300.0mm away from the pocket, and the wiring shall be continued in flexible metal conduit in the form of a loop at least 600.0mm long, with sufficient slack to permit the raising or lowering of the box.

19.6.13

Socket Outlets and Plugs

(1) Socket outlets intended for the connection of arc lamps shall: a) have an ampere rating not less than 40.0A, and

b) be supplied by copper conductors not smaller than 16.0mm2 •


EBCS-10 1995

393


(2) Socket outlets intended for the connection of incandescent lamps shall: a) have an ampere rating not less than 16.0A, and

b) be supplied by conductors not smaller than 4.0mm2 copper or 6.0mm 2 aluminium.

(3) Plugs for arc and incandescent socket outlets shall not be interchangeable. 19~6.14

Curtain Motors

(1) Curtain motors shall be of the closed type.

19.6.15

Flue Damper Control

(1) Where stage flue dampers are released by an electrical device, the circuit operating the device shall, in normal operation, be closed. (2) The circuit shall be controlled by at least two single-pole switches enclosed in metal boxes with self-closing doors without locks or latches. (3) One switch shall be placed at the electrician's station and the other at a suitable place. (4) The device shall be: a) designed for the full voltage of the circuit to which it is connected, or resistance being inserted;

b) located in the loft above the scenery; and

c) enclosed in a suitable metal box with a tight self-closing door.

19.7

PORTABLE STAGE EQUIPMENT

19.7.1 Fixtures on Scenery (1) Fixtures attached to stage scenery shall be: a) of the internally wired type, or

b) wired with flexible cord or cable suitable for hard usage.

(2) The fixtures shall be secured firmly in place.

394

EBCS-10 1995



(3) The stems of the fixtures shall be carried through to the back of the scenery and shall have a suitable bushing on the end thereof

19.7.2 String or Festooned Lights (1) Joints in the wiring of string or festooned lights shall be staggered where practicable. (2) Where the lamps of string or festooned lights are enclosed in paper lanterns, shades, or other devices of combustible material, they shall be equipped with lamp guards.

19.7.3 Flexible Conductors from Portable Equipment (1) Flexible conductors for arc lamps, bunches, or other portable equipment shall be of extra hard-usage type cord or cable; but for separate miscellaneous portable devices operated under conditions where the conductors are not exposed to severe mechanical injury, reinforced cords of ordinary type may be used provided that they are protected by an overcurrent device rated or set at not more than 16.0A.

19.7.4 Portable Equipment for Stage Effects (1) Portable equipment for stage effects shall be of a type acceptable for the purpose and shall be so located that flames, sparks, or hot particles cannot come in contact with combustible material.

ETHIOPIAN BUILDING CODE ,STANDARD

EBCS-10 1995

395

SECTION

20

EMERGENCY SYSTEMS, UNIT

EQUIPMENT, AND EXIT SIGNS

20.1

SCOPE

(l) This Section applies to:

a) the installation, operation and maintenance of emergency system and unit equipment intended to supply illumination and to emergency systems intended to supply power, where required by the authority having jurisdiction, and b) thewiring of exit signs.

20.2

NORMATIVE REFERENCE

(l) The following reference contains provisions which, through reference in this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings.

a) C22.1: 1990

20.3


GENERAL

20.3.1 Capacity (l) Emergency systems and unit equipment shall have adequate capacity and rating to ensure the satisfactory operation of all connected equipment when the general power supply fails.

396

EBCS-10 1995


SECTION 20: EMERGENCY SYSTEMS, UNIT EQUIPMENT, AND EXIT SIGNS

20.3.2 Instruction (1) Complete instructions for the operation and maintenance of the emergency system or unit equipment which shall also specify testing at least once every month to ensure security of operation, shall be posted on the premises in a frame under glass.

20.3.3 Batteries Maintenance (1) When batteries are used as a source of supply, the batteries shall be kept:

a) in proper condition, and

b) fully charged at all times.

20.3.4 Lamps (1) Emergency lights shall be so arranged that the failure of one lamp will not leave the area normally illuminated by it in total darkness.

20.3.5 Circuits (1) No appliance or lamp, other than those required for emergency purposes, shall be supplied

by the emergency circuits. 20.3.6

Method of Wiring

20.3.6.1

General

(1) The method of wiring, including that between unit equipment and remote lamps, shall be in accordance with the provisions of Section 8.

20.3.6.2

Segregation

(1) The wiring shall be kept entirely independent of all other wiring and equipment and shall not enter a fixture, raceway, box, or cabinet occupied by other wiring except, where necessary: a) in transfer switch, and

b) in emergency lighting fixtures supplied from two sources.

ETHIOPIAN SOJ[DING CODE STANDARD

EBCS-10 1995

397

ELECTRICAL INSTALLATION OF BUlLDINGS

20.4

EMERGENCY SYSTEMS

20.4.1 Supply (l) The emergency supply shall be a standby supply consisting of;

a) a storage battery of the rechargeable type having sufficient capacity to supply and maintain the total load of the emergency circuits at not less than 91 % of the full voltage for the time period required by the authority having jurisdiction, but in no case less than Y2hr, and be equipped with a charging means to maintain the battery in a charged condition automatically. Note:

Automobile batteries and lead batteries not of the enclosed glass-jar type are not considered suitable.

b) a generator driven by a dependable prime mover and it shall be: i) of capacity sufficient to carry the load, and ii) arranged to start automatically without failure and without undue delay upon the failure of the current supply of the principal equipment of the building.

iO.4.2 Control (l) The current supply for emergency systems shall be controlled by an automatic transfer switch which energizes the emergency system upon failure of the normal current supply and is accessible only to authorized persons.

20.4.3 Overcurrent Protection (1) No device capable of interrupting the circuit, other than the overcurrent device for the current supply of the emergency system, shall be placed ahead of the branch circuit overcurrent

device.

20.4.4

Audible and Visual Trouble Signal Devices

20.4.4.1

Trouble signal

(l) Every emergency system shall be equipped with audible and visual trouble signal devices which give warning of derangement of the current source or sources and which indicate when the emergency load is supplied from batteries or generators.

398

EBCS-10 1995


SECTION 20: EMERGENCY SYSTEMS, UNIT EQUlPMENT, AND EXIT SIGNS

20.4.4.2

'Wiring

(I) Audible trouble signals may be wired so that: a) they can be silenced, but a red-warning or trouble light shall continue to provide the protective function,and

b) when the system is restored to normal, the audible signal will:

i) sound, thus indicating the necessity of restoring the silencing switch to its normal position, or ii) reset automatically so as to sound for any subsequent operation .of the emergency system. 20.4~4.3

Voltage drop

(1) the voltage drop in the wiring feeding lamps mounted remotefrom thecurrent supply shall

not exceed 5% ofthe applied voltage.

2'0.5

UNITEQUIPMENT

20.5.1 Mounting (I ) Each unit equipment shall be mounted with the bottom of enclosure not less than 2;Om

above the float wherever practicable. Note:

Unit equipment for emergency lighting is definedasanitemofequipment that: i) is intended to.provide automatically, in response toa failure of a power supply to which it is connected,

specified light output and a specified amount ofpower forillumination purposes, for aspecifiedpeniod . of time, but in any case not less than 30.0min; Ii) comprises, in a unit construction, a storage battery, charging:meanstomaiIitainthebatteryin a charged condition automatically, lamps, Of outputterminals towhich specificallylisted lamps maybe connected, means to energize the lamps when the normal power supplyfailsandto de-energize the lamps when the normal power supply is restored, and means to indicate and test the operating conditions of the equipment.


EBCS-10 1995

399

ELECTRICAL INSTALLATION OF BUILDI~GS

20.5.2

Supply Connections

20.5.2.1

Outlet distance

(1) Outlet point to which unit equipment is to be connected shall be not more than 1.5mfrom the location of the unit equipment.

20.5.2.2

Connection to supply

(1) Unit equipment shall be permanently connected to the supply if: a) the voltage rating exceeds 230.0V, or

b) the marked input rating exceeds 24.0A.

(2) Where the above ratings are not exceeded, the unit equipment may be connected using the flexible cord and attachment plug supplied with the equipment.

20.5.2.3

Installation

(1) Unit equipment shall be installed in such a manner that it will be automatically actuated upon the failure of the power supply to the normal lighting in the area covered by that unit

equipment.

20.5.2.4

Feeding

(1) Unit equipment shall be fed, where practicable, from the same panel board, and may be fed from the same branch circuit which feeds the normal lighting in the area covered by that unit

equipment.

20.5.2.5

Voltage drop

(1) The circuit conductors to lamps mounted remote from supply SOUrce shall be of such size that the voltage drop does not exceed 5% of the marked output voltage of the unit equipment.

20.5.1.6

Excess load

(1) The number of lamps connected to single equipment shall not result in a load that is in

excess of the

watt output rating marked on the equipment for the required emergency period. '.

400

EBCS-10 1995


SECTION 20: EMERGENCY SYSTEMS, UNIT EQUIPMENT, AND EXIT SIGNS

20.6

EXIT SIGNS·

20.6.1 Power Supply (1) The power supply for exit signs shall be provided from:

a) a separate circuit or circuits used for no other purpose, or

b) the circuit supplying exit lighting

20.6.2 Wiring (1) Exit signs shall be wired in accordance with the provisions of Section 8 of this Code.

-...


EBCS-10 1995

401

..

~'

SECTION

21

MOTION PICTURE STUDIOS, PROJECTION

ROOMS, FILM EXCHANGES AND FACTORIES

21.1

SCOPE

(1) This Section sets provisions and installation requirements that apply to motion-picture studios, projection rooms,exchanges, factories and any building in which motion-picture films, pyroxylin plastic and nitrocellulose x-ray and photographic films are manufactured, projected,developed, printed, rewound, repaired or stored. 21.2


(1) The followingreferencescontain provisions which,through reference in this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings:

a) C22.1:1990


b) NFPA70/NEC:1986

National Fire Protection Association I American National Electrical Code, 1987 Edition

21.3

GENERAL

21.3.1 Wiring Method (1) The wiring-method.unless specified otherwise in subc1auseofthisSection, shall be rigid conduit, steel electrical metallic tubing, or mineral-insulated cable. -(2) The wiring for stage-set lighting, stage effects, electric equipment used as stage properties, and other wiring not fixed as to location, shall be done with approved flexible cords and cables.

402

EBCS-tO 1995


SECTION 21: MOTION PICTURE STUDIOS, PROJECTION ROOMS, ETC

(3) For portable lamps other than those used as properties in a motion-picture set on a studio stage or similar location, the lamp holders shall be: a) unswitched,

b) of composition or metal sheathed procelain, and

c) provided with a guard hook and handle.

21.4

VIEWING, CUTTING AND PATCIllNG TABLE FIXTURE

(1) All lighting fixtures, except lamps forming an integral part of table equipment, shall be of the totally-enclosed gasketted type. 21.5

FILM VAULTS AND STORAGE ROOMS

21.5.1 Equipment in Film Vaults and Storage Rooms (1) In rooms used for storage of pyroxylin plastic, no socket outlet or attachment plugs shall be installed. (2) .No electrical equipment other than that necessary for fixed lighting shall be installed in film vaults. 21.5.2 Wiring Method in Film Vaults (1) The wiring method in film-vault.shall be rigid-conduit or mineral-insulated cable only, with threaded joints at couplings boxes and fittings. (2) Conduit or cable shall not run directly from vault to vault, but only form the switch to the lighting fixture within the vault. (3) Conduit shall be sealed off near the switch enclosure with a fitting and compound approved for the purpose. 21.5.3 Lighting Fixtures in Film Vaults (1) Lighting fixtures in film vaults shall be of the explosion-proof type approved for the use in Class I Group C hazardous locations and shall have metal cages or guards protecting the globs.


EBCS-10 1995

403


(2) The fixtures in (1) above shall be located as close as practicable to the ceiling to avoid their being damaged through handling of film containers. 21.5.4 Film Vault Circuits (1) Fixtures shall be controlled by a double pole switch located outside the film vault. (2) A red pilot light shall be provided to indicate when the switch is closed and shall be located outside the film vault. (3) Wiring shall be arranged so that, when the switch is off, all conductors within the film vault will be dead. 21.6

MOTION PICTURE PROJECTION ROOMS

21.6.1 Lamps in Projection Rooms (1) Incandescent lamps in projection rooms or booths shall be provided with a lamp guard unless otherwise protected by noncombustible shades or other enclosures. 21.6.2 Arc Lamp Current Supply (1) Motor generator sets, frequency changers, transformers, rectifiers, rheostats, and similar equipment for the supply or control of current to arc lamps or projectors shall be located in a room separate from the projection room. 21.6.3 Ventilation (1) Exhaust ventilation fans for the projection room shall be controlled from inside the projection room. 21.7

MOTORS AND GENERATORS

(1) Motors and generators having brushes or sliding contacts, other than those used on studio stages or those installed in accordance with Clause 21.6.2, shall be of approved dust tight or enclosed types.

404

EBCS-10 1995


SECTION

22

DIAGNOSTIC IMAGING INSTALLATION

22.1

SCOPE

(1) This Section of the Code applies to the installation of x-ray and other diagnostic imaging equipment operating at any frequency. However, it does not specify safeguards against direct, stray, or secondary radiation emitted by the equipment.

22.2


(1) The following references contain provisions which, through reference in this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings: a) C22.1: 1990


b) NFPA70INEC:1986

National Fire Protection Association/American National Electrical Code, 1987 Edition.

22.3

DEFINITIONS

(1) For the purpose of this Section, in addition to the tenns defined in Section 1, the following definitions shall apply when referring to x-ray or,computerized tomography equipment,

longutlme rating

a rating that is applicable for an operating period of'S.Omin or more.

momentary rating

a rating that is applicable for an operating period of not more than 20.0s.

ETHIOPIAN BUILDIN'G CODE STANDARD

EBC.S-10 1995

405


22.4

mGH-VOLTAGE GUARDING

(1) High-voltage parts shall be mounted within metal enclosures that are bondedto earth except when installed in separate rooms or enclosures where a suitable switch shall be: a) provided to control the circuit supplying diagnostic imaging equipment, and b) arranged so that it will be in an open position except when the door of the room or enclosure is locked. (2) High voltage parts of diagnostic imaging equipment shall be insulated from the enclosure. (3) Conductors in the high voltage circuits shall be of the shock-proof type. (4) A milliammetre, if provided, shall be: a) connected, if practicable, in the lead that is bonded to earth.,or b) guarded if connected in the high voltage lead.

22.5·

CONNECTIONS TO SUPPLY ClkCUIT

(1) Permanently connected diagnostic imaging equipment shall be connected to the power source by means of a wiring method meeting the general requirements of this Code except that equipment properly supplied by a branch circuit rated at not over 30.0A shall be permitted to be supplied through a suitable attachment plug and hard-service cable or cord.

(2) Mobile diagnostic imaging equipment of any capacity may be connected to its power source by .suitable temporary connections and hard-usage cable or cord.

22.6

DISCONNECTING MEANS

_(1) A disconnecting means of adequate capacity for at-least 50% of the input required for the momentary rating or 100% of the input required. for the long-time rating of. x-ray or: computerized tomography equipment, whichever is greater, shall be provided in the supply circuit in a location readily accessible from the radiation control.

406

ESC5-10 1995


SECTION 22: DIAGNOSTIC IMAGING INSTALLATION

22.7

TRANSFORMERS AND CAPACITORS

(1) Capacitors forming part of a diagnostic Imaging equipment shall be provided with an automatic means for discharging and grounding the plates whenever the transformer primary is disconnected from the source of supply unless all current-carrying parts of the capacitors and of the conductors connected therewith are: a) at least 2.5m from the floor and are inaccessible to unauthorized persons, or b) within metal enclosures that are bonded to earth or within enclosures of insulating material if within 25m of the floor.

22.8

CONTROL

(1) For stationary equipment, the low-voltage circuit of the step-up transformer shall contain an overcurrent device which:

a) has no exposed live parts, b) protects the radiographic circuit against fault conditions under all operating conditions, and c) is installed as part of the equipment or adjacent thereto. (2) Where as in (1) above, the design of the step-up transformer is such ~at branch fuses having a current rating lower than that of the overcurrent device are required for adequate protection for fluoroscopic and therapeutic circuits, they shall be added for the protection of these circuits. (3) For portable equipment, the requirements of (1) and (2) above shall apply; but, the overcurrent device shall be located in or on the equipment except that no current-limiting device is required when the high-voltage parts are within a single metal enclosure that is provided with a means for bonding to earth. (4) Where more than one piece of equipment is operated' from the same high-voltage circuit, each piece or group of equipment, as a unit, shall be provided with a high-voltage switch or equivalent disconnecting means.


EBCS-10 1995

407

ELECTRlCAL INSTALLATION OF BUILDINGS

·22.9

AMPACITY OF PROTECTION

SUPPLY CONDUcrORS

AND RATING OF

OVERCURRENT

(1) The ampacity of supply conductors and the rating of overcurrent protection devices shall not be less than:

a) the long-time current rating of x-ray or computerized tomography equipment, or b) 50% of the maximum momentary current rating required by x-ray or computerized tomography equipment on a radiographic setting. (2) Theampacity of conductors and the rating of overcurrent protection devices for two or more branch circuits supplying x-ray or computerized tomography units shall not be less than: a) the sum of the long-time current rating of all x-ray or computerized tomography units which are intended to be operated at anyone time, or b) the sum of 50% the maximum momentary current rating for x-ray or .computerized tomography equipment on a radiographic setting for the two largest units plus 20% of the maximum current rating of the other units. 22.10 .BONDING

(1) Non-current-carrying parts of tube stands, tables and othes apparatus shall be bonded to earth in accordance with the requirements of Part I, -Section 7 of this Code.

----------

408

EBCS-10 1995


SECTION

23

ELECTRICAL COMMUNICATION SYSTEMS

23.1

SCOPE

(1) This Section applies to the installation of electrical communication systems including information processing systems.

23.2

NORMATIVE REFERENCE

(1) The following reference contains provisions which, through reference In this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings: a) C221: 1990

23.3

Canadian Electrical Code Part 1, Safety Standard for Electrical Installations, Sixteenth: Edition.

GENERAL

23.3.1 Circuits in Communication Cables (1) Radio and television circuits, r;emote control circuits, fire alarm circuits, or parts thereof shall be:

a) permitted to use conductors in a cable assembly of communication building entrance having other conductors used as communication circuits, b) deemed to be communication circuits within the portions of circuits that use conductors within the communication building entrance cable assembly, and c) suitably protected at the point of interface connection with the communication cable conductors.


EBCS-10 1995

409

. ELECTRICAL INSTALLATION OF BUILDINGS

23.3.2 Hazardous Locations (1) Where the wiring orelectrical equipment within the scope of this Section is installed in hazardous locations as defmed in Sections 11, 12, or 14, it shall also comply with the applicable Clauses of those Sections.

23.3.3 Approved Transformers . .(1) Where transformers or other devices supply current to a communication circuit. from an> electric supply circuit, the transfomiers or other devices shall be of a type approved for the service.

23.4

INSIDE CONDUCTORS

23.4.1. Conductors Arrangement (1) Conductors shall be neatly arranged and'secured in place in aconvenient and workmanlike . . manner.

. (2) Raceways for communication circuits'shall be installed in accordance with the requirements of Section 10 and, in case of metal, they shall be earthed in accordance with the provisions of . Section 7.

23.4.2 Insulation (1) Wire and cable used for communication system in a building shall be of the approved types as specified in Annex B, Section 4 of this Standard.

; 23.4.3 Earthing Conductors with an Outer Metal Covering (1) Where a conductor or cable is equipped with an outer metal covering, the covering shall be earthed.

23.4.4 Separation from Other Conductors (1) The conductors of an electrical communication system in buildings shall be separated at least

. SO.Omm from any insulated conductor of a Class 1 circuit or an electric light or power system

410

EBCS-10 1995


SECTION 23: ELECTRICAL COMMUNICATJON SYSTEMS

operating at 380.0V or less, and shall be separated at least 600.0mm from any insulated conductor or an electric light or power system operating at more than 380.0V unless: a) one system is in earthed metal raceways, metal sheathed cable, or earthed armoured cable, 'b) the Class 1 circuit or electric light or power system operating at 380.0V or less utilizes a nonmetallic sheathed cable or hard-usage or extra-hard-usage flexible cord, or c) both systems are permanently separated by a continuous, firmly fixed non-meta! raceway in addition to the insulation of the conductors. (2) Where the light or power conductors are bare, all communication conductors in the same room or space shall be enclosed in an earthed metal raceway and. no opening, such as an outlet box, may be located within 2.0m of bare conductors of up to and including 15.0kV or.within / 3.0m of bare conductors above 15.0kV. (3) The conductors of an electrical communication system shall not be placed in any outlet box, junction box, raceway, or similar fitting or compartment which contains conductors of electric light or power systems or of Class 1 circuits (as defined in Section 10) unless: a) the communication conductors are separated from the other conductors by an acceptable partition, or b) the power or Class 1 conductors are placed solely for the purpose of supplying power to the communication system, or for connection to remote control equipment. (4) The conductors of an electrical communication system in a building shall not be placed in a shaft with the conductors of an electric light or power system unless: a) the conductors of all systems are insulated and are separated by at least 50.0mm, or b) the conductors of either system are encased in noncombustible tubing.

23.4.5 Penetration of a Fire Separation (1) Conductors of communication circuits extending through a fire separation shall be installed so as to limit the spread of fire.

23.4.6 Communication Cable in Hoistways (1) Special permission shall be required to install communication conductors in hoistways.


EBCS-10 1995

411

ELECTRICAL INSTALLATIQN OF BUILDINGS

(2) All conductors, except travelling cables, shall be totally enclosed in continuous metal raceway. (3) Pullboxes required for communication interconnection shall be located outside the hoistway. 23.4.7 Communication Conductors in Ducts and Plenum Chambers (1) .Communication conductors shall not be placed in ducts or plenum chambers except as permitted by relevant Clauses of Section 8. 23.4.8 Data Processing Systems (1) The interconnecting' cables used in data processing systems shall be permitted to contain power and communication conductors where such cables are specifically approved for the purpose.

23.4.9 Conductors under Raised Floors (1) Conductors or communication circuits shall be allowed to be installed, without additional mechanical protection, under a raised floor provided that: a) the raised floor is of suitable noncombustible construction; b) at least a 50.0mm separation is provided and maintained where the conductors are used to serve data processing systems and are placed parallel to any other power supply wiring; and c) the conductors serve the equipment located only on the floor above the raised floor, . where the space under the raised floor is used as an air plenum. 23.4.10

Conductors in Concealed Installations

(1) Where the ends of cables or conductors are not terminated on a device, they shall be capped or taped.

412

EBCS-10 1995


SECTION 23: ELECTRICAL COMMUNICATION SYSTEMS

23.4.11

Type CFC Under-Carpet Wiring System

23.4.11.1 General (l) The provisions of Clause 23.4.11 apply to the installation of communication flat-cable-type (CFC) systems which, together with the connecting devices, shall be approved or acceptable for the purpose.

23.4.11.2 Use permitted (1) Type CFC system wiring shall be permitted to be used: a) only under carpet squares not exceeding 750.0mm, and any adhesive used shall be of release type; b) as an extension of conventional wiring to serve areas or zones, and each run of wiring from the transition point shall not exceed 15.0m; c) on hard, smooth, continuous floor surface made of concrete if sealed, ceramic or composition flooring, wood, or similar material; . d) in dry or interior damp locations;

e) on floors heated in excess of 30°C only, if approved and identified for that purpose.

23.4.11.3 Use prohibited (l) Type CFC system wiring shall not be used:

a) b) c) d) e)

outdoors or in wet locations;

where subject to corrosive vapours or liquids;

in hazardous locations;

in dwelling units;

in hospitals or institutional buildings except in office areas;

f) on walls except when entering the transition point;

g) under permanent type partitions or walls.


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23.4.11.4 Floor protective coverings (l) Type CFC system wiring shall be covered with abrasion resistant tape, secured to the floor so as to completely cover all cables, comers, and bare conductor ends.

23.4.11.5 Coverings (l) Type CFC system wiring shall be permitted to cross over or under each other, and over or under power supply system wiring provided there is a layer of earthed metal shielding between the CFC and the power supply system cables.

23.4.11.6 System height (l) Type CFC system wiring shall not be stacked on top of each other except as required to enter the transition point.

23.4.11.7 Earthing of shields (1) Type CFC system wiring equipped with.a metal shield shall be earthed.'

23.5

EQUIPMENT

23.5.1 Communication Equipment in Bathrooms (1) Communication equipment located in a bathroom shall be permanently fixed on the wall, and shall be located so that no part may be reached or used from the bath or from the shower enclosure; however, it shall be permitted to be actuated by means of a cord with an insulating link. , (2) Communication jacks shall not be located in a bathroom.

23.5.2 Equipment in Air Ducts, Plenums, or Suspended Ceilings (1) Communication equipment and terminals shall not be placed in ducts, plenums, or hollow spaces which are used to transport air nor in suspended ceiling areas except where a duct, plenum, or hollow space is created by a suspended ceiling having lay-in panels or tiles; connecting blocks which are a non-protective type may be installed provided they are placed in an accessible enclosure.

414

EBCS-10 1995



23.5.3 Exposed Equipment and Terminations (1) Exposed communication equipment and/or associated terminations shall be located in a suitable room separate from electrical ·light or power installations, except where necessary to place them in a joint-use room in which case a minimum separation of900.0mm from electrical equipment requiring adjustment and maintenance shall be provided and maintained.

23.5.4 Earth Circuits (l) Communication circuits connected to a telecommunication network and having return path via local earth or other circuitry which similarly could present a fire hazard, shall be provided with a current-limiting device installed in or adjacent to the equipment of a type recommended by the equipment manufacturer as suitable for the application, which will limit the current under normal operating conditions and under fault conditions, to prevent fire hazards.

23.5.5 Communication Systems in Hospitals (1) Exposed non-current-carrying metal parts, if they could become. energized, of communications equipment, other than telephone sets, installed in general, intermediate, and critical care areas. of hospitals shall be earthed to conform with the requirements of Clause 14.4.2(5).

23.6

OUTSIDE· CONDUCTORS

23.6.1 Overhead Conductors on Poles (1) The installation of overhead communication conductors on poles in proximity with power conductors shall be established in conformity with the rules and regulations of the Ethiopian Electric Light & Power Authority (EELPA).

23.6.2 Overhead Conductors on Roofs (I) Communication conductors passing over buildings shall be kept at least 205m above any roof which may readily be walked upon. (2) Communication conductors shall not be attached to the upper surfaces of roofs or be run .within 2.0m, measured vertically, of a roof without special permission.


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23.6.3 Lightning Conductors (1) Separation of at least 2.0m shall, where practicabl~, be maintained between conductors of communication circuits on buildings and lightning conductors.

23.6.4 Swimming Pools (1) Where wires or cables are installed over or adjacent to swimming pools, they shall be paced in accordance with the provisions of Clauses 25.4.2 and 25.4.3 of Section 25.

23.7

UNDERGROUND CIRCUITS

23.7.1 Direct Buried Systems (1) Where communication conductors or cable assemblies are direct buried, the sheath shall be suitable for direct burial and the conductor or cable assembly shall: a) not be installed in the same vertical plane with other underground systems, except when installed in accordance with (g) below; b) maintain a minimum horizontal separation of 300.0mm from other underground systems, except when installed in accordance with (g) below; c) not be less than 600.0mm deep, unless rock bottom is encountered at a shallower depth in which case a minimum depth of 4S0.0mm shall be permitted, except that for service wire under parkways and lawns, the depth may be reduced to 4S0.0mm; d) be placed with a layer of sand 7S.0mm deep, both above and below the cable, if in rocky or stony ground; e) not be less than 900,Omm deep under an area which is subject to vehicular traffic, except that the depth may be reduced to 600,Omm when mechanical protection is provided, . which shall consist of: i) treated plank at least 38.0mm thick or other acceptable material which shall be placed over the conductor or cable after first backfilling with 7S.0mm of sand or earth containing no rocks or stones, or ii) a conduit suitable for earth burial placed to facilitate cable replacement and to minimize traffic vibration damage;

416

EBCS·10 1995



f) not be placed in a common trench involving random separation with power supply cables

or wires operating at over 750.0V; and g) have a metal sheath when placed in a common trench involving random separation with power supply cables or wiring operating at 750.0V or less, in which case the communication conductor or cable assembly shall not cross under the supply cables,

23.7.2 Underground Raceway (1) Where communication conductors or cable assemblies are placed in underground raceway systems: a) the raceway, including laterals, shall be separated from those used forthe electric power system by not less than 50.0mm of concrete or 300.0mm of well-tamped earth; b) the raceway shall be located to maintain minimum depth of 600.0mm in areas subject to vehicular traffic and, 450.0mm in all other areas, except that where rock bottom is encountered at a shallower depth, the raceway shall be encased in concrete; c) the raceway shall not terminate in the same .manhole, and the conductors or cable assembly shall not be placed in the same manhole used for electric power system; d) the cables shall not be placed in the same raceway containing electric lighting or power supply cables; and e) the cable sheath shall be suitable for wet locations.

23.8

EARTHING

23.8.1Bon~ing

of Cable Sheath

(1) Where cables, either overhead or underground, enter buildings, the metal sheath or shield of the cable shall be bonded to earth as close as practicable to the point of entrance or shall be interrupted as close as practicable to the point of entrance by an insulating joint or equivalent device.


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23.8.2 Cable-Sheath Bonding Conductor (1) The cable-sheath bonding conductor required by Clause 23.8.1 shall have an ampacity equal to or greater than that of the outer conductive sheath of the exposed cable except that the bonding conductor shall not be required to be larger than 10.0mm 2 copper. 23.8.3 Earthing Electrode (1) Earthing conductor shall preferably be connected to a water-pipe earthing electrode as close to the point entrance as possible.

of

(2) Where waterpipe is not readily available and the earthing conductor of the power consumer's service is connected to the water pipe at the building, the communication system earthing conductor may be connected to the metal conduit, service equipment enclosures, or to . . . the earthing conductor of the power consumer's service. \

a

(3) In the absence of waterpipe, the communication earthing conductor may be connected to an effectively earthed metal structure or toan earth rod or pipe driven into. permanently damp earth; but: a) steam, gas, or hot water pipes or lightning rod conductors shall not be used as earthing electrodes; and b) a driven rod or. pipe used for earthing power circuits shall not be used as a: communication earthing electrode unless it is connected to the earthed conductor of a multi-earthed power neutral. (4) Where a driven earth rod or pipe is used as an earthing electrode for an electrical communication· system, it shall be separated by at least 2.0m from any other electrodes, including those used for power circuits, radio, lightning rods, or for any other purpose and shall be bonded only to that of the power circuits in accordance with applicable Clauses of Section 7. (5) The nonnallength of driven earth rod used as the earthing electrode for a communication system is 15m; but, where the normal rod would not reach moist soil when installed, a rod of suitable additional length shall be used.

418

EBCS-10 1995



23.8.4 Earthing Electrode Connection (1) The earthing conductor shall be attached to an earthing electrode by means of an approved bolt clamp except that, in the case of an earth rod, a wire lead may be permanently connected to the rod. _(2) Where a bolt clamp is used, the earthing conductor shall be soldered or otherwise acceptably connected to the clamp in an effective manner. 23.8.5 Bonding of Electrodes (l) A copper conductor not smaller than 10.0mm2 shall be connected between communication and power earthing electrodes when separate artificial earthing electrodes are required as described per Clause 23.8.3.


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419

SECTION

24

COMMUNITY ANTENNA INSTALLATION FOR RADIO AND TELEVISION RECEPTION

24.1.

SCOPE

(l) This Section applies to the installation of:

a) community antenna assembly, b) head station (amplifier and other power sources), and c) distribution network (conductors, branching boxes and antenna or feeder outlets).

24.2


(l) The following references contain provisions which, through reference in this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings:

a) C22.1:1990

.Canadian electrical Code, Part 1, Safety Standard for Electrical Installations, Sixteenth Edition.

b) IEC 597

Aerials for the Reception of Sound and Television Broadcasting in the Frequency Range 30.0MHZ to 1.0GHZ:

i) Part 1-1977, Electrical and mechanical characteristics. ii) Part 2-1977 Methods of measurement of electrical performance parameters. . iii) Part 3-1983 Methods of measurement of mechanical properties, vibration and environmental tests. iv) Part 4-1984 Guide for the preparation ofaerial performance specification, detailed specification sheet format.

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SECTION 24: COMMUNITY ANTENNA INSTALLATION

c) IEC 728: 1982

24.3

Cabled Distribution System Primarily Intended for Sound and Television Signals Operating between 30.0MHz and I.OGHz.

TECHNICAL REQUIREMENTS

24.3.1 Mechanical (I) A community antenna shall comply with- all mechanical properties or requirements outlined

in the IEC 597 and IEC 728. 24.3.2 Electrical (I) A community antenna shall:

a) be designed for the reception of signals within the permitted bandwidth for sound and television broadcasting; b) be immune to extraneous signal interference; and c) comply with all ether necessary electrical parameters that are required for the satisfactory operation of the system (see IEC 597 and IEC 728).

24.4

EQUIPMENT

24.4.1 Community Antenna Distribution Amplifiers and Other Power Sources (l) Amplifiers and other devices which supply current to a community antenna distribution circuit from an electric supply circuit shall be approved for the purpose.

(2) Where amplifiers and other power devices are connected to an electric supply circuit and enclosed in a cabinet, the cabinet shall be so .located as to be readily accessible and shall be adequately ventilated. (3) The chassis and cabinets of the community antenna distribution amplifier or other power sources, the outer conductive shield of the coaxial cables, and the metal conduit or the metal cable sheath enclosing the electric supply conductors shall all be connected to the system earth with a minimum of 16.0m2 copper conductor.


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(4) Where a cabinet containing an amplifier or other power device is mounted accessible to the public, it shall be provided with a lock or similar closing device.

24.4.2 Exposed Equipment and Terminations (1) Exposed community antenna distribution equipment and/or associated terminations shall be located in a suitable room or similar area, separate from electrical light or power installations, except where necessary to place them in a joint-usc room in which case a minimum separation of 900.0mm from electrical equipment requiring adjustment and maintenance shall be provided and maintained.

24.4.3 Equipment Earthing (1) Non-powered equipment and enclosures or equipment powered exclusively hy the coaxial cable shall be considered earthed when they are effectively connected to the earthed outer conductive coaxial cable shield.

24.5

COMMUNITY ANTENNA DISTRIBUTION NETWORK

24.5.1 Conductor (1) The conductors used in the distribution network shall consist of coaxial cable having inner conductor and an outer conductive shield of circular cross-section.' (2) Conductors placed within buildings shall be of the approved types as specified in Annex B, Section 4, of this Code. (3) Conductors placed outside of buildings shall be of the types that are acceptable for the application.

24.5.2 Voltage Limitation (1) The coaxial cable shall be permitted to deliver low energy power to equipment directly associated with the community antenna distribution circuits if the voltage is not over 60.0V and if the current supply is from an approved amplifier, transformer, or other device having energy limiting characteristics.

422

EBCS-10 1995



24.5.3 Hazardous Locations

(1) Where the circuits or equipment within the scope of this Section are installed in hazardous locations, they shalt also comply with the applicable Clauses of Sections 12, 13 and 14. 24.5.4 Supports (l) Where conductors are attached to or supported on buildings, the attachment or supporting

fixtures shall be acceptable for the purpose. 24.5.5 Earthing of Outer Conductive Shield of a Coaxial Cable (l) Where coaxial cable is exposed to lightning or to accidental contact with lightning arrester

conductors or power conductors operating at voltage exceeding 380.0V-to-earth, the outer conductive shield of the coaxial cable shall be earthed at the building as close to the point of cable entry as possible. (2) Where the outer conductive shield of a coaxial cable is earthed, no other protective device shall be required. (3) Earthing of a coaxial cable shield by means of a protective device shall be permitted provided that the device does not interrupt the earthing system within the building. 24.5.6 Earthing Conductor (l) The earthing conductor for the outer conductive shield of a coaxial cable shall have rubber

insulation not less than O.8mm in thickness, and shall be covered by a substantial fibrous covering except that conductors acceptable for the purpose, having less than O.8mm rubber insulation, or having other kinds of insulation, may be used. (2) The earthing conductor shall be of copper. (3) The earthing conductors shall be not smaller than 2.5mm2 • (4) The earthing conductor shall have an ampacity equal to or greater than that of the outer conductive sheath of the exposed coaxial cable.


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423

ELECTIiICAL INSTALLATION OF BUILDINGS

(5) Where two or more coaxial cables, which have outer conductive shields differing in size and ampacity, join at a common connection to the earthing conductor, the ampacity of the earthing conductor shall be equal to or exceed the ampacity of the largest coaxial outer conductive shield. (6) The earthing conductor shall be fun from the coaxial cable shield to the earthing electrode in as straight a line as possible. (7) The earthing conductor shall be protected in situations where it is or can be exposed to mechanical damage. 24.5.7 Earthing Electrode (1) Earthing electrodes shall conform to the requirements of relevant Clauses of Section 7.

(2) Where artificial earthing electrodes are installed, they shall be in accordance with applicable Clauses of Section 7 except that the minimum driven length of the rod electrode shall be 2.0m. (3) Artificial earthing electrodes for community antenna distribution shall be spaced and bonded with other electrodes in accordance with relevant Clause of Section 7. 24.5.8 Earthing Electrode Connection (1) The earthing conductor shall be attached to an earthing electrode by means ofan approved earth clamp except, in the case of an earth rod, a wire lead may be permanently connected to the rod and the wire lead connected to the earthing conductor by means of pressure connector or other acceptable means.

(2) Where an earth clamp is used, the earthing conductor shall be acceptably connected to the clamp in an effective manner. 24.6

CONDUCTORS WITHIN BUILDINGS

24.6.1 Separation from Other Conductors (1) Conductors of community antenna distribution circuits shall be separated at least 50.0mm from insulated conductors of electric lighting, power, or Class 1 circuits operating at 380.0V or less, and shall be separated at least 600.0mm from any insulated conductor of an electric

424

EBCS-10 1995

ETHIOP~AN

BUILDING CODE STANDARD


lighting, power, or Class 1 circuit operating at more than 380.0V unless effective separation is afforded by use of: a) earthing metal raceways for the community antenna distribution circuits, or for the electric lighting, power and Class 1 circuits, b) earthed metal sheathed or armoured cable for the electric lighting, power, and Class 1 conductors, c) nonmetallic sheathed cable for the electric lighting, power, and Class 1 circuits operating at 380.0V or less, or d) raceways of a non-metal type as permitted in Section 8 in addition to the insulation on the community antenna distribution circuit conductors, or the electric lighting power, and Class 1 circuit conductors. (2) Where the electric lighting or power conductors are bare, all community antenna distribution conductors in the same room or space shall be enclosed in an earthed metal raceway and no opening, such as an outlet box, shall be located within 2.0m 'of bare conductors of up to and including 15.0kV or within 3.0m of bare conductors above 15.0kV. (3) The conductors of a community antenna- distribution circuit shall not be placed in any raceway, compartment, outlet box, junction box, or similar fitting which contains conductors of electric light, power, or Class 1 circuit unless: a) the conductors of the community antenna distribution circuit are separated from the electric light, power, or Class 1 circuit conductors by an acceptable barrier, or b) the power or Class 1 conductors .are placed solely for the purpose of supplying power to the community antenna distribution circuit.

24.6.2 Conductors in a Vertical Shaft (1) Conductors of a community antenna distribution circuit in a vertical shaft shall be in a totally enclosed noncombustible raceway.


EBCS-10 1995

425


24.6.3 Penetration of a Fire Separation (l) Conductors of a community antenna distribution circuit extending through fire separation shall be so installed as to limit fire spread. 24.6.4 .Community Antenna Distribution Conductors in Ducts and. Plenum Chambers (1) Community antenna distribution conductors shall not be placed in ducts or plenum chambers except as permitted by relevant Clauses of Section 2 and Section 8 of this Code. 24.6.5 Raceways (1) Raceways shall be installed in accordance with the requirements of Section 8. 24.7

CONDUCTORS OUTSIDE OF BUILDINGS

24.7.1 Overhead Conductors on Poles (1) The installation of overhead community antenna distribution conductors in proximity with power conductors on poles and in aerial spans between buildings, poles, and other structures shall be established in conformity with rules and regulations of EELPA . 24.7.2 Overhead Conductors on Roofs (l) Community antenna distribution conductors 'passing over buildings shall be kept at least 2.5m above any roof which may be readily walked upon. (2) Community antenna distribution conductors shall not be attached to the upper surfaces of roofs or be run within 2.5m, measured vertically, of a roof without special permission. 24.7.3 Conductors on Buildings (l) Community antenna distribution conductors on buildings shall be separated from insulated light or power conductors not in cable or conduit by at least 300.0mm unless, in addition to the insulation on the conductors, they are permanently separated by a continuous and firmly fixed non-metal type raceway as permitted in Section 8 .

426

EBCS-10 1995


SECTION 24: COMMUNITY ANTENNA INSTALLAT10N

(2) Community antenna distribution conductors subject to accidental contact with light or power conductors operating at voltages exceeding 380.0V and attached exposed to buildings shall be separated from combustible material by being supported on glass, porcelain, or other insulating material acceptable for the purpose, except that such separation is not required where the outer conductive sheath of the coaxial cable is earthed. (3) Community antenna distribution conductors attached to buildings shall not conflict with other communication conductors attached to the. same building and sufficient clearance shall be provided so that there will not be unnecessary interference to maintenance operations; and in no case should the conductors, strand, or equipment of one system cause abrasion to the conductors, strand, or equipment of the other system.

24.7.4 Conductors Entering Buildings (1) The community antenna distribution conductors shall enter the building either through a noncombustible, non-absorptive insulating bushing or through a metal raceway except that the insulating bushing or raceway may be omitted where" the"entering conductors pass through masonry or are acceptable for the purpose. 24.7.5 Swimming Pools

(1) Where conductors are installed over or adjacent to swimming pools, they shall be placed in accordance with the provisions of Clauses 25.4.2 and 25.4.3, Section 25 of this Code.

24.8

UNDERGROUND CONDUCTORS

24.8.1 Direct Buried Systems (1) Where community antenna distribution conductors are direct buried, the sheath shall be suitable for direct burial and the conductor shall be: a) installed outside of the same vertical plane which contains differing underground conductors other than communication conductors, except when installed in accordance with (f) below; b) maimtained at a minimum horizontal separation of 300.0mm from differing underground conductors other than communication conductors, except when installed in accordance with paragraph (f) below; I" ;


EBCS-10 1995

427

ELECTRICAL INSTALl ATION OF BUILDINGS

c) placed at a minimum depth of 600.0mm, unless rock bottom is encountered at a shallower depth, in which case a minimum depth of 450.0mm shall be permitted, except that for service wires under parkways and lawns, the depth may be reduced to 450.0mm; d) placed with a layer of sand 75.0mm deep, both above and below the cable, if in rocky or stony ground; e) placed at a minimum depth of 900.0mm under an area which is subject to vehicular traffic, except that the depth may be reduced to 600.0mm when mechanical protection is provided which shall consist of: i) treated plank at least 38.0mm thick or other acceptable material which Shall be placed over the conductor or cable after first back-filling with 75.0mm of sand or earth containing no rocks or stones; or ii) a conduit suitable for earth burial placed to facilitate cable replacement and to minimize traffic vibration damage; and f) equipped with a metal shield when placed in a common trench involving random

separation with power supply cables or wiring operating at 750.0V or less, in which case the community antenna distribution conductors shall not cross under the supply cables. 24.8.2 Underground Raceway (1) Where community antenna distribution conductors are placed in underground raceway systems:

a) the raceway, including materials, shall be separated from those used for the electric power system by not less than 50.0mm of concrete or 300.0mm of well-tamped earth; b) the raceway shall be located to maintain a minimum depth of 600.0mm in areas subject to vehicular traffic and 450.0mm in all other areas except that, where rock bottom it encountered at shallower depth, the raceway shall be encased in concrete; c) the raceway shall not terminate in the same manhole and the conductors or cable assembly shall not be placed in the same manhole, used for electric po~er system; d) the conductors shall not be placed in the same raceway containing electric lighting, power or Class 1 circuit conductors; and e) the cable sheath shall be suitable for wet locations..

428

EBCS-10 1995

ETHIOPIAN BUILDING CODE STAND...I\RD

SECTION 24: COMMUNrlY ANTENNA INSTALLATION

24.8.3 Underground Block Distribution (1) Where the entire street circuit is run underground and the circuit is placed so.that it is,not liable to be in contact with electric lighting, power, or Class I circuits of more than 380.0V, insulating bushings or raceways shall not be required where the circuit conductors enter a building.

24.9

LIGHTNING ARRESTERS FOR RECEIVING STATIONS

24.9.1 Lightning Arrester (1) A lightning arrester shall:

a) be provided for each lead-in conductor from an outdoor antenna to a receiving station except where such lead-in conductor is protected by a continuous earthed metal shield between the antenna and the point of entrance to the building; b) be located outside the building or inside the building between the point of entrance or the lead-in and the radio set or transformer, and as near as practicable to the entrance to the conductors to the building; and .' c) not be located near combustible material nor in a hazardous location.

24.9.2

Earthing Conductor

24.9.2.1

Material

(1) The earthing conductor shall be of copper, aluminium alloy, copper-clad steel, bronze, or other corrosion-resistant material unless otherwise specified.

24.9.2.2

Insulation

(1) The earthing conductor may be uninsulated,

24.9.2.3

Support

(1) The earthing conductor shall be securely fastened in place and may be directly attached to the supporting surface without the use of insulating supports.


EBCS-10 1995

429


24.9.2.4

Mechanical protection

(1) The earthing conductor shall be protected where

24.9.2.5

l:XPOSl:U

to mcchunicul injury.

Earthing conductor to be run in a straight line

(1) The earthing conductor shall be run. in as straight a line as is practicable from the lightning arresters of antenna mast, or both, to the earthing electrode.

24.9.3

Earthing Electrode

24.9.3.1

Earthing electrode

(1) The earthing conductor shall be connected to an earthing electrode as specified in Section 7.

24.9.3.2

Earthtng conductors

(1) The earthing conductor may be run either inside or outside the building.

24.9.3.3

Size ofprotective earth

(1) The size of protective earthing conductor for receiving stations providing earth connection for mast and lightning arresters shall be in accordance with the provisions of Section 7.

24.9.3.4

Common earth

(1) A single earthing conductor may be used for both protective and operating purposes; but it must be installed so that disconnection of the operating earth will not be after the protective earth circuit.

\ \

<..,

430

EBCS-10 1995


ANNEX

A (INFORMATIVE)

ANTENNA (AERIAL) SYSTEMSt

A.I

GENERAL

A.I.!

Introduction

An efficient antenna installation is one of the prerequisites for interference-free reception of radio and television transmission. This can be expected to perform satisfactorily only if it has been competently desinged and constructed.

A.I.2 Terminology

individual antenna,

antenna installations that supply radio and television signals to a single household. Modem household are provided with a number of antenna sockets. To make an adequate signal level available at each socket, amplifiers may also be required in some individual antenna installations (see Figure A.I).

community antenna system

antenna installations that supply radio and television signals to households in one or more buildings. They consists of an antenna assembly, a head station (amplifier unit) and the distribution network including the cables, branch-in units, antenna sockets and the associated receiver connection cables (see Figure A.3). It is usual nowadays to install community aerial systems in apartment buildings. They are considerably more satisfactory

than large number of individual antennas because mutual interference is eliminated and the most suitable position on the roof can be chosen for the antenna.

t

See Siemens' Electrical Installation Handbook, Part 3, 1979, Siemens.


EBCS-10 1995

431


private wide-band system

a special form of the community antenna installation. The signals to be received are fed to the private wide-band system from a primary cable network (see Figure A.2).

A.l.3 Regulation and Specification

Broadcast receiving antenna installations must comply with the requirements and regulations of the Ethiopian Telecommunication Authority, if any, or shall meet the technical requirements outlined in any applicable international standard. A.2

PLANNING

Before the planning of a system is started, an accurate survey of the site should be carried out. In the process, the following data should be collected with the aid of the building plans <;>r from the direct observation: Number and position of antenna sockets - Modem antenna system should be equipped with at least two, and preferably three or four, antenna sockets per apartment. The number and position of the sockets must be known for planning purposes. Sound and television broadcast transmissions - The choice of transmission that are worth receiving depends on the reception conditions. If these are not known, measurement must be undertaken with a suitable signal-strength meter. Position of antenna - The antenna should be erected in the most satisfactory position for reception and be as far positioned as possible from chimney and power cables. Amplifiers, frequency-converters and power-supply units - A readily accessible location should be determined for the head station under the roof. It must also be confirmed that a connection to the electricity supply is available, or can be provided, close to the head unit. (see, Figure A.3) Quality of reception - To assess the quality of reception, it is necessary to make measurement with a suitable signal strength meter. The measurement point is determined by the antenna location appropriate to the building. If a different location is more satisfactory from the point of view of reception, it should be adopted after consultation with the building owner or the architect.

432

EBCS-10 1995



A.3

DISTRIBUTION SYSTEM

A.3.t

General

The distribution system begins at the output of the head station and ends at the antenna socket outlets. Its purpose is to prov ide reliable transmission of the signal from the head stations through the sockets to the radio and television receivers. A.3.2 Junction Boxes

Distribution boxes and branching boxes are generally referred to by the term "junction boxes".

Distribution boxes are advantageous where main feeders are run close together, e.g. in apartment

blocks and high-rise buildings, in which no long feeder lines are necessary.

In long buildings or terrace houses, the use of branching boxes is more satisfactory.

Examples of different types of junction boxes are shown in Figure A.4.

A.3.3 Antenna Sockets

Antenna socket outlets are distinguished according to their mode of application in the distribution network and their transmission characteristics. Depending on the application, there are available through-wired sockets, which are used in network arranged on the loop-through principle (socketsfed in series, Figure A.5) and spur sockets which are intended for main-feeder networks arranged in the spur-line pattern (sockets fed in parallel, Figure A.6). A.3.4 Combined Distribution Method In a combined distribution method, the sound radio and television signals are carried over the same main reeders, The antenna socket outlets incorporate a socket for the sound radio and . another for the television. Figure A.7 shows the combined distribution method applied to a community antenna system with three television channels. Figure A.8 provides a similar arrangement with six television channels.


EBCS-10 1995

433


A.3.5 Private Wide-Band System Private wide-band cable-network systems supply subscribers on demand with radio and television transmissions. These arc comparable in terms of design to large community antenna systems. The transmissions are obtained from a broadcast receiving station and relayed via cables and amplifiers to system connection points on the perimeters of the private properties. Following this, the received signals are amplified and fed to the antenna sockets (see Figure A.9). A.4

PROTECTION

As a protection against accidental voltage transfer from the electrical installations, all inactive conductive parts of the antenna system, such as the antenna post, housings, junction boxes and amplifiers, outer conductors and metallic sheaths of the antenna cables should be connected together and earthed, or included in the potential equalization system. For potential equalization, a permanent connection must be made between the antenna system and the main equipotential conductor (see Figure A.I 0). A.5

CONSTRUCTION OF A RECEIVING-ANTENNA SYSTEM

A.5.l

General

Reliable performance by radio and television receivers is dependent upon the careful planning and competent construction of the aerial installation. Information relative to the length and design of the antenna post is presented in Figure A.ll and A.I2. A.5.2 Length of Aerial Post The necessary length and strength of the post is determined by the number and separation of the antennas. The upper end of the tubular post is usually closed by the LFIMF/HF and USW antennas. The order of the other antennas is immaterial in itself. It is appropriate, however, to mount the antennas that present a high wind load near the bottom so long as higher placing is not called for on grounds of efficient reception.

434

EBCS-10 1995

ETHIOPIAN BUILDI'NG CODE STANDARD

SECTION 24: COMMUNIlY ANTENNA INSTALLATION

A.5.3

Minimum Antenna Separation

Guidance values for the minimum separation "a" in centimeters, between the antennas on the post are given in Table AI. The separation should be increased for antennas with a larger

number of elements, particularly if they are aimed in the same direction.

The separation between the lowest antenna unit and the roof should be at least 1.Om.

Table A.1 Guidance values for the minimum separation "a" [em] between antennas on the spot

A.5.4

Reception Band

TVI

USW

TVIH

TV IV

TVV

TVI

250

140

140

80

80

USW

140

110

80

80

80

TV III

140

80

80

80

80

TV IV

80

80

80

60

50

TVV

80

80

80

50

50

Wind load and Bending Moment

The bending moment in the tubular antenna post is calculated from:

M,

=

W1xL 1 + W2xL2 + .... (Nm)

(AI)

where, L is length [m ] and W is windload [N]. A post should be chosen where permissible bending moment (from the manufacturer's data) is at least equal to the calculated bending moment M, in Equation (AI). The capacity of the structural parts (buildings) to withstand the forces produced in the antenna installation shall be verified.

A.5;5

Mounting of the Headstation

The headstation is best mounted under the roof in the immediate vicinity of the antenna post (Figure AI3). It should be ensured that a loop is formed in the cable (a water trap) before it


EBCS-10 1995

435


enters the head station to prevent condensate from running out of the tabular post into the amplifier (Figure A.14). Attention should be paid to good accessibility in consideration of subsequent maintenance. If there is no suitable wall on which to mount the headstation, it can be mounted on a wooden board or frame. Where headstations are mounted in public-accessible places such as, for example, in stair walls, they should preferably be accommodated in lockable cabinets. A.6

COMMISSIONING AND MAINTENANCE

A.6.1 Measurement on Commissioning Such measurements should be carried out in commissioning as are necessary to prove the technical performance of the aerial system. Table A.3 shows a measurement schedule, representing a community antenna system in tabular form, in which the test points and the required measurements are detailed and the results record. To assess picture quality, the assessment symbols given in Table A.2 should be entered in the measurement schedule. Table A.2 Assessment grades for interference according to prescribed assessment criteria

Assessment criteria Assessment of interference

Assessment grades

Viewing .distance relative to picture height

For common channel interference (G)

For reflected signal interference (R)

For interference (8)

0

Not visible

0

one half

GO

RO

SO

1

Not visible

1

5 times

G1

R1

S1

2

Just visible

2

5 times

G2

R2

S2

3

Clearly

3

5 times

G3

R3

S3

visible

436

EBCS-10 1995



A.6.2 Measurement of Amplifier Output Signal Level In recording the amplifier output signal level in the headstation, the signal levels from the individual band amplifiers (LF/MF/HF, USW, VHF, UHF) are measured using a calibrated receiver and compared with the maximum permissible output signal levels of the amplifiers according to the manufacturers' data. In this process, the manufacturer's instructions for the measurements and for the proper adjustment of the amplifiers should be followed.

A.6.3 J1aintenance Trouble-free operation of the aerial system is assisted by regular checking of the mechanical and electrical components . . The following routine checks should be carried out during maintenance; a) Aerial structure:

- Orientation of aerials,

- Fixing clamps,

- Sealing of roof lead-in,

- Seating of earthing clamps.

b) Headstation: - Measurements as for commissioning at test points TP 1 and TP2. - The checking and measurement results from each maintenance operation should be recorded in a suitable schedule Table AA for comparison with other tests.


EBCS-10 1995

437


Tobie A.3 Measurements on eommisslonlng (entries in the measurement schedule)

Recommended additional measurements

Measurements of commissioning

Difference between vision and sound carrier signal levels in the TV channels

Tes t-

poin t

Test-point position

Signal-level measurement' (Values in dB/J.V)

Picture quality

Sound quality

."'-"'1.""_

11'1

I:nd of aerial down-lead

x

TP2

Output of each amplifier, converter or other active electronic unit

x

TP3

Output of the first receiver

connecting

lead of

each main

or spur

cable

x

Ouput of the last

re.ceiver connecting lead of each main

or spur cable

x

TP4

x

x

x

Observe maximum permissible output signal level according to catalogue data (see "lining-up" instructions)

Note hum, cracking,

noi~R and hiss

x .._-

x

Attenuati on distortio n introduc ed by head station ~2 dB

LF/MF~94

USW ~80

TV I ~84

TV 1I~84

TV IVNs;84

LF/MF ~ -6 dB relative to reference aerial USW mono ~40 USW stereo ~50

TV I ~52 TV III ~54

TV IVN ~57

x

·w

--TPI

[ \7'

.

"V

~TP2

--T1'3

--TP4

x Insert appropriate entries

1")

For sound broadcast transmissions, the selectively measured carriers: at least the r.m.s. values of the local and district transmitters in the LF, MF, HF and USW bands should be measured. For television transmissions, the channel signal levels (the r.m.s. level of the vision carrier at the point where the synchronizing pulses occur) in the receiving or distribution channels

2)

Assessment of picture quality.

438

EBCS-10 1995


I SECTION 24: COMMUNITY ANTENNA INSTALLATION

Table A.4 Maintenance schedule Amplifier station: __.. Consumer: Address:

........N9.:;

_

.

Project:

._

.

No.:

* • • _ • • _-~.--------------------------------------------_._--------------------.----- •••• - ••• _ •••• _----------_ •• _-------------_._--_ ••• _------------------------._-_.

Amplifier Input/output channel

TPl

Date: Name:

Name:

Date; Signal leve [dB"V]

-

Street No.:

Picture quality

nB,n't [dB]

TPl

TP2 TPl

TP2

R

G

Date: Name:

aR [dB]

TP2

5

R

G

5

Ch ...I...

Ch...I... Ch .. .1... Ch .. .1...

Ch...1... Ch...1... Ch...1... Ch...1... ./ 1

Ch...1... Ch...1... Ch...1...

USW input/output channel

~ignal

leve dB"V

TPl

Assessment of sound: (hum, chrackling, noise, hiss)

TP2

LF/MF Aerial structure:

Geometry, mechanical firmness Seating of earthing clamps Equipotential bonding Sealing of roof lead-in


EBCS-10 1995

439

~

2;

LF/MF/Hi'/USWaerial

i:.F/MF/HF/USWaerial

,VHFaerial

DO

DO o Aerialsocket

a) With one aerial socket

Figure A.I Structure of an individual aerial installation

DO DOlO .. ~ . """,;,,",

b) With two aerial sockets and an amplifier


CP . ConneeliCJl1 point . WC nelWQrK Wlde.ban~ c~ble nelw0if< Main distributionsyslem', led from below

~t

tJ:!Jh

iK\:~:i\ :i;:J:'r§;~~IT~;:\'.:;'.i:':i.: ! .

'VHF wide·band ampillier ,I' ::Jlaee of previous headsialion In loll .\. . 'Maindlslrlbulion . ."'Syslem, led Irom neove '\ .

"-

CPtoWCnelwork Wide·bond In basemenlamplilier In basemer1

. CPto'We n(llwork in bas('fT;eni

,'CP to WC notwork . •In basemen I ' '

Apartment building

a)

New buildings connected to wideband cable system

b) Existing community aerial installation

Figure A.2 Private wide-band systems

Figure A.3 Structure of a community aerial installation with 24 subscribers


EBCS-10 1995

441


"'WI ~

caOlt I 2-.IY· : dlSUIbuLiOn

I l3-wlY

tC.'UlbI.ltJon

~~

I ~ '.4·""',V .

Idllr;buliOft

-rh:....

.

btanflina 00,(

I

OISlflbl.&l!O" I Oo.b"

cable, I br"'1C"'lng

Sing"

MIII'lClbl'~:

"I-~~'n -'y~r 1~·I1'· (-~--!flr--'--""'T'----'

: ": II 11'1: ·11 :., I .t l

::

\1

I I I Ollll\Dullon tabl..

I)

II I I

I I :I II

Distribution bo~c$ for IWO. three and (our mJ,in COlbln .

I

I Olllribufion CoIDlt

I

J

DI,uIDuUQ·, CIOlt

b) Btlnl:hi" bOle, (lJt

one ilnd ,wo main I:abl"

Figure A.4 Types and applications of junction boxes

O',qiDutlQn

...,.

..,.

OilillbUlio.f .

~

O~DI. l)rII\Ctllng bOll

I ~-.} p,ng n. __

e-rn---e..

'j

Th'OlJgn,whd IOCllill

Spur.lint 1OCk.11

•'III1ln .d'C:OUPlinQ,>~.rwork'

sock,.

.t.'11I wiln Itlmmllin;;',nIIIOr (15 t1J

Figure A.5 Through-wired method

442

EBCS-10 1995

()olJbl, branching OOl\""''; llrtrjnung '..i..:..../75 ru:

Fig. A.6 Spur-line method



lF/MFI Ch"

't

, I

LF/MFI

USW If{t6 ~I I

I I I

'

I I

I

I I

the

't' I I I

C~2

I I

I

I I

'

J

!

I

HI-I

tI

en 21

Ch 0,

I

'V

I

Ht'l

WSW

t'"Cn3ti ;

'V I I II

en a

t

I I II

Uh12 I I

I I

I I

I

I I

I

b II n

Community aerial system for LF, MF, HF and USW reception and six television transmissions

Figure A.8

Figure A.7 Community aerial system for LF MF, HF and USW reception and three television transmission

V+--J

Private wide-band system

;:?I/ ~rr~

&i1 :=::;:;:L-,

'--fI}

~~J

I

'"t'

~r1J~ Figure A.9 Wide-band cable network with private wide-band system


EBCS-10 1995

443


\\ Connaction 01Ina

aar~';;o"

(ana ins complete aerial SUlJCllH81 101M eqvrpcrenual bonding bar

r

$$$$~' - ~\', ' ,

. .

~:::I~~~~~r~~i~~~l~~~~~~~y~ir.~

./ aerialcables 10Ine etnncotentut bonding Oar

1/-'1 (1,l2;1.3 - conductors Ph_so

I

I I I

N -

neuuatconductor

I

.j~~:i~~~:jt~t~~~~E± Figure A.tO Protection of an aerial installation by inclusion in the equipotential bonding of all the metallic conducting systems of a building

.r

LF/MFIHF aenal

~v,

T a

USWaerial

Figure A.ll Data relevant to the length of, an aerial post

444

EBCS-10 1995

Figure A.12 .Data relevant to the design of an aerial post



Figure A.13 Recommended arrangement of a head station

I"

.

I· I '.

Figure A.14 Formation of a "water trap"


EBCS-1 0 ·1995

445

SECTION

25

SWIMMING POOLS, FOUNTAINS AND SIMILAR INSTALLATION·

25.1

SCOPE

. (1) This Section applies to electrical installations, electrical equipment in or adjacent to pools, and non-electrical metal accessories in a pool or within 3.0m of the inside wall of a pool. Note:

The term "pool", asreferred to in this Section, is deemed to include permanently installed and storable pools, hydromassage bathtub, spas and hot tubs, wadding pools, baptismal pools.-and decorative pools.

25.2

NORMATIVE REFERENCE

(1) The following reference contains provisions which, through reference in this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings: a) C 22.1: 1990

25.3

Canadian Electrical Code, Part 1, Safety Standard Electrical Installation, Sixteenth Edition.

DEFINITIONS·

(1) In this Section, in additions to the terms defined in Section 1, the following definitions shall apply:

permanently installed swimming pool a pool constructed in such a manner that it cannot be disassembled for storage. storable swimming pool

446

EBCS-10 1995

a pool constructed in such a manner that it may be readily disassembled for storage and reassembled to its original integrity.


SECTION 25: SWIMMING POOLS, FOUNTAINS AND SIMILAR INSTALLATION

forming shell

a structure intended for mounting in a swimming pool structure to support a wet-niche luminaire assembly.

wet-niche luminaire

a luminaire intended for installation in a forming shell mounted in a pool structure where the luminaire will be completely surrounded by pool water.

dry-niche Luminaire

a luminaire intended for installation in the wall of a pool in a niche which is sealed against the entry of pool water by a fixed lens.

spa or hot tub

a pool or tub designed for the immersion of persons in heated water circulated in closed system incorporating a filter, heater, pump, and with or without a motor driven blower, but not intended to be filled and drained with each use.

hydromassage bathtup

a permanently installed bathtub having an integral or remote waterpump or air blower, and having a fill and drain water system, and includes therapeutic pools.

leakage current collector

a section of corrosion resistant metal tubing at least five times as long as its diameter, provided with a brazed or welded copper lug .placed in a run of nonmetallic pipe to provide a path to earth for currerit leakage originating from device in contact with pool water.

decorative pool

a pool that could be used as a wadding pool that is larger than 105m in any dimensions and that is readily accessible to the public.

25.4

GENERAL

25.4.1 Equipment Installation (1) Equipment shall not be installed in the walls nor in the water of pools except as permitted by this Section.


EBCS-10 1995

447

· ELECTRICAL INSTALLATION OF BUILDINGS

25.4.2

Overhead Wiring

25.4.2.1 General

(l) There shall not be any overhead wiring above the pool, diving structures, observation stand, tower or platform, or above the area extending 3.0m horizontally from the pool edge (see

Figure 25.1) except as permitted by 25.4.2.2 and 25.4.2.3. 25.4.2.2

Communication conductors and cables not exceeding 750.0V

(1) Insulated communication conductors, communication antenna distribution conductors, and , neutral supported cables not exceeding 750.0V shall be permitted to be .located over a pool, diving structure, observation stand, tower or platform, or above the area extending 3.0m horizontally from the pool edge, provided there is a clearance measured radially of at least 4.5m.

25.4.2.3

CQI,ductors operating at no more than 50.0kV

(1) Conductors other than those covered by 25.4.2.2 and operating at not more than 50.0kV phase-to-phase shall be permitted to be located above a pool, diving structure, observation stand, tower Of plate, or above the area extending 3.0m horizontally from the pool edge provided there is a clearance measured radially of at least 705m.

25.4.3 Underground Wiring (1) The horizontal separation between the inside walls of pool and underground conductors, except for bonding conductors or conductors supplying electrical equipment associated with the pool and protected by an earth fault circuit breaker, shall be not less than that shown in Table 25.1.

448

EBCS-10 1995



Table 25.1 Minimum conductor separation from pools -

~

Minimum separation [m] Type of Installation

Communication conductors Electrical conductors 0- 750.0V 751V - 15000.0V 15001V - 25000.0V

25.4.4

Bonding to Earth

25.4.4.1

General

Conductor buried directly in ground

Conductor in underground raceways

1.5

0.75

0.75 3.00 4.00

0.75 1.50 2.00

'.

(1) The metal parts ofthe pool and other non-electrical equipment associated with the pool such as piping, pool reinforcing steel, ladders, diving board supports, and fences within 1.5m of the pool, shall be bonded together and to non-current carrying metal parts of electrical equipment such as decorative type-pool luminaries and lighting equipment not located in a forming shells, metal screens of shields for underwater speakers, conduit, junction boxes, and the like by a copper bonding conductor. Exemption: The metal parts of a pool need not be bonded to earth or to each other where the electrical equipment

associated with the pool is: a) not located within 3.0m of the pool, b) suitably separated from the pool by a fence, wall, or other barrier, or c) approved without a bonding conductor

25.4.4.2 Reinfordng steel (1) Pool reinforcing steel shall be bonded with a minimum of four connections equally spaced around the perimeter.


EBCS-10 1995

449


25.4.4.3

Bonding conductor size

(1) Bonding conductors for pools shall be:

a) no smaller than 16.0mm2 for permanently installed pools and for all in-ground pools; or b) as required by Table 7.1 of Section 7 for all other pools.

25.4.4.4

Bonding medium

(1) Metal sheath and raceways shall not be relied upon as the bonding medium and separate copper bonding conductor shall be used. Exemptions: a) A metallic conductor between a forming shell and its associated junction box shall he permitted to be used as the bonding medium provided the forming shell and junction box are installed in the same structural section.

b) The bonding conductor shall be of copper and not smaller than that required by Table 7.1.

25.4.4.5· Junction box bonding conductor (1) The bonding conductor from the junction box referred to in Clause 25.4.5 shall be run to the main distribution board, and, if it is smaller than 16.0mm2, it shall be installed and mechanically protected in the same manner as the circuit conductor.

25.4.5

Junction and ])eck Boxes

25.4.5.1

General

(1) Junction boxes:

a) shall be permitted to be submerged in decorative pools provided the boxes are marked for such- usage; and b) conduits shall be water-tight and provided with a packing seal that will seal-around the cord and effectively prevent water from entering the box through the conduit from the forming shell.

450

EBCS-10 1995



25.4.5.2 Deck boxes (l) Junction 'installed on the supply side of conduits extending to forming shells, referred hereinafter as "deck boxes", shall be specifically approved for the purpose and shall:

a) be provided with a means for independently terminating at least three bonding conductors inside the box and one i6.0mm2 bonding conductor outside the box; b) not contain the conductors of any circuits other than those used exclusively to supply the underwater equipment; and c) be provided with electrical continuity between every connected metal conduit and.the bonding terminals by means of copper, brass or other corrosion-resistant metal that is integral with the box.

25.4'.5.3 Deck box installation (1) Deck boxes shall be installed: a) above the normal water-level of the pool;

b) so that the top of the box is located at or above the finished level of the pool deck;

c) in a manner or location that the box will not bean obstacle; and

d) in such a manner that any water on the deck will drain away from the box.

25.4.6

Transformers and Transformer Enclosure

25.4.6.1 Location (1) .Transformers shall not be located within 3.0m of the inside wall of the pool unless suitably separated from the pool area by a fence, wall or other penn anent barrier which will make the transformer not accessible to persons using the pool area. 25.4.6.~

Bonding

(1) A metal shield, if provided between the primary and secondary windings of a transformer, shall be bonded to earth.


EBCS-10 1995

451

·i1.'.~

ELECTRICAL INSTALLATION OF BUILDtNGS

25.4.6.3

Audio transformer

(1) Audio isolation transformers shall:

a) be connected between the audio output terminals of each amplifier and any loudspeaker which is located within 3.Om of the pool wall; and

b) be located in or adjacent to the amplifier with which they are used; and

c) have an audio output voltage of not more than 75.0V r.m.s,

25.4.7

Socket Outlets

25.4.7.1

Location

(1) Socket outlets shall not be located within 1.5m of the inside walls of the pdols.

25.4.7.2

Protection

(1) Sockcl'uutlets located between 1.5m and 3.Om of the inside wall of a pool shall be protected by an earth-fault circuit breaker. Note:

In maintaining the

d~ensions

referred to in Clause 25.4.7, the distance to be measured is the shortest path that the power supply cord of an appliance connected to the socket outlet would follow without piercing a building floor, wall, or ceiling.

25.4.8

Luminaries and Lighting Equipment

25.4.8.1

Wet-niche or submersible luminaire

25.4.8.1.1

General

(1) Wet-niche luminaries shall, except for decorative pools, be mounted in forming shells which shall have provision for suitable connection to the wiring method used .

. 25.4.8.1.2

Submersion depth

(1) Wet-niche luminaries shall, unless specifically approved and marked for submersion at a greater depth, not be submersed in the pool water at a depth of more than 600.0mm, such distance being measured from the centre of the lense face of the luminaire to the normal water level.

452

EBCS-10 1995



25.4.8.1.3

Voltage

(1) Wet-niche luminaire shall operate with neither the supply voltage to the luminaire nor the associated ballast or transformer, if applicable, nor the secondary open-circuit voltage of the ballast or transformer exceeding 230.0V during either starting or operating voltage.

25.4.8.2

Dry-niche luminaire

25.4.8.2.1

Voltage

(1) Where dry-niche luminaries are installed so as to be accessible from a walkway or a service tunnel outside the walls of the pool or from a closed drained recess in the wall of the pool, neither the supply voltage to the fixture nor its associate ballast or transformer shall exceed 380.0V during either starting or operating conditions.

25.4.8.2.2

Accessibility

(1) Dry-niche luminaries shall be accessible for maintenance: a) from a service tunnel or walkway outside the walk of the pool, or b) through a handhole in the deck of the pool to a closed, drained recess in the wall of the pool.

25.4.8.3

Metal parts

(1) Metal parts of lumnaires in contact with the pool water shall be of brass or other suitable corrosion-resistant material

25.4.8.4

Luminaire support

(1) Stands or supports for luminaries shall not be installed within 3.0m of the inside walls of a swimming pool unless such luminaries are protected by earth-fault circuit breaker.

25.4.8.5

Luminaire protection

(1) Luminaries installed below or within 3.0m of the pool surface or walls, and not suitably separated from the pool area by fence, wall or other pennanent barrier shall be electrically protected by an earth-fault circuit breaker.


EBCS-10 1995

453


------~_--------

25.4.8.6

Forming shell types

(1) Forming shells for lamps supplied from an earthed circuit or a circuit operating at voltage exceeding 30.0V shall be made from metal and have provision for a threaded connection to a rigid metal conduit.

25.4.9

Earth-Fault Circuit Breakers

25.4.9.1

General

(1) Except as permitted in 25.4.9.2, earth-fault circuit breakers required per the provisions of Clause 25.4.9 shall be of Class A type'.

25.4.9.2 Other classes (1) Where earth-fault circuit breakers of the Class A type are not available due to rating, the

equipment shall be protected by an earth-fault circuit breaker which will clear an earth fault within the time specified for Class A type breaker.

25.4.9.3 Installation (l) Earth-fault circuit breakers shall be:

a) permanently connected, b) permitted to be applied to a feeder, a branch circuit or an individual device, c) installed in a location which will facilitate testing required in 25.4.9.4, but not closer within 3.0m of the pool water.

25.4.9.4

Waming sign

(1) A warning sign shall be located beside the switchescontrolling circuits, electrically protected by earth-fault circuit breakers, advising that the circuits are protected and that the equipment shall be tested regularly.

t See Clause A.2, Annex A.

454

EBCS-10 1995


---~--------~-


25.5

PERMANENTLY INSTALLED SWIMMING POOLS

25.5.1 General (1) The wiring between the wet-niche luminaries and the junction boxes referred to in Clause 2-5.4.5 shall be of flexible cord suitable for use in wet locations and supplied as a part of the luminaire.

25.5.2 Conduit Type (1) Rigid conduit of copper or other corrosion-resistant metal or rigid PVC conduit shall be provided between the forming shell of luminaire installed below the pool surface and the . junction box referred to in Clause 25.4.5. Exemption: Where Clauses 25.5.1 and 25.5.2 do not apply, any suitable wiring method specified in Section 8 of this

Standard shall be permitted.

25.5.3 Circuit Segregation (1) Conductors on the load side of each earth-fault circuit breakers shall be kept entirely independent of all other wiring which is not so protected and shall not enter a luminaire raceway, box, or cabinet occupied by other wiring except for panelboards which house the breakers. 25.5.4 Drainage (1) Conduits in the walls and deck of a swimming pool shall be installed so that suitable drainage is provided. 25.6

STORABLE SWIMMING POOLS

25.6.1 Electrical Equipment /

(1) No electrical equipment shall be located in the pool water or on the pool wall unless specifically approved for the purpose.


EBCS-10 1995

455


25.6.2

Pumps

25.6.2.1

General

(1) Swimming pool pumps located within 3.0m of the pool walls shall be specifically approved

for the purpose.

25.6.2.2

Supply

(1) Swimming pool pumps shall be supplied from a permanently installed receptacle located not less than 1.5m nor more than 7.5m from the pool walls.

25.6.2.3 'Protection (1) Swimming pool pumps shall be protected by an earth fault-circuit breaker if located within

3.0m of the inside walls of the pool and not suitably separated from the pool area by a fence, wall, or other permanent barrier.

25.7

HYDROMASSAGE BATHTUB

25;7.1 Protection (1) Electrical equipment forming an integral part of a hydromassage bathtub shall be protected by an earth-fault circuit breaker of the Class A type.

25.7.2

Control

25.7.2.1

Timer switch

(1) A hydromassage bathtub shall be controlled by an automatic shut-off timer with an "on" time of not more than 30.0min.

25.7.2.2

Controls location

(1) Electrical controls associated with a hydromassage bathtub shall be located behind a barrier or shall be located not less than 1.0m horizontally from a wall of the bathtub unless they form an integral part of an approved factory-built hydromassage bathtub.

456

EBCS-10 1995

ETHIOPLI\N BUILDING CODE STANDARD


25.7.2.3

Earth fault circuit breaker location

(1) Subject to 25.7.2.2 and notwithstanding the provisions of 25.4.9.3(1c), earth-fault circuit breakers shall be permitted to be closer than 3.0m to the pool but not less than 1.5m from the pool wall.

25.7.3 Other Electric Equipment (1) Luminaries, switches, socket outlets, and other electrical equipment not directly' associated with a hydromassage bathtub shall be installed in accordance with relevant Clauses of this Code covering the installation of equipment in bathrooms.

25.8

SPAS AND HOT TUBS

25.8.1

Bonding to Earth

25.8.1.1

General

(l) Metal parts of spas and hot tubs shall be bonded together and to earth in accordance with the provisions of Clause 25.4.4. Exemption:

Metal rings or bands used to secure staves or wooden hot tubs need not be bonded.

25.8.1.2

Bonding conductor size

(1) A copper bonding conductor whose size is not less than that of the circuit conductors

supplying the equipment shall be connected between tile control panel of a spa or hot tub and the consumer's service or distribution panel.

25.8.2

Controls and Other Electrical Equipment'

25.8.2.1

Controls

(I) Controls for spa or hot tub shall be located behind a barrier or shall be located not within

1.5m horizontally from spa or hot tub unless they form an integral part of an approved factory built spa or hot tub.

EBCS-10 1995

ETHIOPIAN BUILDING CODE STANDARD ~

457


25.8.2.2 Socket outlet (1) Socket outlets shall be installed in accordance with Clause 25.4.7.

25.8.2.3 Luminaries (1) Luminaires shall be installed in accordance with Clause 25.4.8.

25.8.3

Leakage Current

25.8.3.1 Installation (1) Leakage current collectors shall be installed in all water inlets and in all water outlets ofa

field-assembled spa or hot tub so that all water flows through leakage current collectors. Exemption: Leakage water current collection shall not be required in a system in which the only component is a pump marked as "insulated wet-end pump".

25.8.3.2 Insulation and bonding (1) Leakage current collectors-shall be electrically insulated from the spa or hot tub and shall be bonded to the control panel or the main service earth with a copper bonding conductor.

25.8.3.3 Bonding conductor size (1) The bonding conductor for leakage current collectors shall be not smaller than that required by Table 7.1, Section 7, where the bonding conductors are mechanically protected in the same manner as the circuit conductor or a minimum 16.0mm2 copper conductor.

25.8.4

Field-Assembled Units

25.8.4.1 General (1) Spas and hot tubs, field-assembled within divided components, shall be installed in accordance with the provisions of Clauses 25.8.1 through 25.8.3, 25.8.4.2 and 25.8.4.3.

458

EBCS-10 1995


...

l<,

SECTION 25: SWiMMING POOLS, FOUNTAINS AND SIMILAR INSTALLATION

25.8.4.2

Component

(1) Individual components, such as pumps, heaters, and blowers, shall be specifically approved for use with spas or hot tub.

"

25.8.4.3

Air blower installation

t'!'o.

(1) Air blower shall be installed above the tub rim. or other acceptable means shall be used to prevent water from coming into contact with live parts of the blower.

I

---.......

')--~JI

Ic-r--/ ---~ 7.~ ~ ..1~5 /~f"": 2.

,..--

I

..S

----/

f

J,.S .

Note:

Pool qUlpm~

~.S

I

No conductors would be permitted under any circumstances in the area under line 1. In the area above Line 1 insulated communication conductors and neutral supported cables operating at 750.0V or less might be permitted. Any other conductors operating at not more than 50.0kV might be permitted above the area outlined by line 2. All dimensions are in metres.

Figure 25.1 Minimum clearances of conductors over swimming pool


EBCS-10 1995

459

ANNEX

A.1

A (INFORMATIVE)

AUDIO ISOLATION TRANSFORMERS

Audio isolation transformes should: a) have either the primary and secondary windings wound on separate bobbins on the core legs or a grounded metal shield between the primary and secondary windings; and b) be capable of withstanding a 60.0Hz test voltage of 2500.0V applied between the primary and secondary windings for a period of 1.0min without a breakdown. Microphones used in the vicinity of pools and baptismal fonts must have audio isolation transformers and cables with ungrounded conductors installed between them and any mixer, preamplifier, amplifier or similar equipment.

A.2

AN EARTH FAULT CIRCUIT INTERRUPTER

An earth-fault circuit interrupter is a device whose function is to interrupt, within a predetermined time, the electric circuit to a load-when the current to earth exceeds some predetermined value that is less than that required to operate the overcurrent protective device of that circuit. More specifically, a Class A earth-fault circuit interrupter is one which will interrupt the circuit to the load when the earth-fault current is 6.0mA or more, but not when the earth fault current is 4.0mA or less in a time: »: a) not greater than that given by:

.T

460

20

(A.I)

I

EBCS-10 1995



where

T is the time in seconds, I is the earth fault current in r.a.ms milliamperes for fault currents between

4.0mA and 260.0mA. Note: when the ambient air temperature is less than -SoC or more than 4crC, the minimum tripping current may be 3.5mA instead of 4.0mA.

b) not greater than 25.0ms for earth-fault currents over 260.0mA. In addition, a Class A earth-fault circuit interrupter should be capable of interrupting the circuit to the load in keeping with the above requirements should the identified circuit conductor (neutral) become inadvertently earthed between the interrupter and the lo~d. The prime function of a Class A EFCI, therefore, is to provide protection against hazardous electric shocks from leakage current flowing to earth from defective circuits or equipment. It does not provided protection against shock should a person make contact with two of the circuit conductors on the load side of the EFCI. An EFCI must be applied to a circuit in accordance with the type and rating of the circuit for which it is designed.


EBCS-10 1995

46·1

SECTION

26

GRAPHICAL SYMBOLS

26.1

SCOPE

(1) This Section of the Code sets provisions for graphical symbols to be used in electrical installations and degree of protection provided by enclosures for electrical equipment. 26.2


(1) The following references contain provisions which, through reference in this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings: a) IEC 529:1989

Degree of protection provided by enclosures (IP Code).

b) DIN 407117:1983

Graphical Symbols Installation.

26.3

for

Diagrams

Electrical

DEFINITIONS

(1) For the purpose of this Section of the Code, the following definitions shall apply, in addition to the terms defined in Section 1: degree ofprotection

the extent of protection provided by an enclosure against access to hazardous parts, against ingress of solid foreign objects and/or against ingress of water and verified by standardized test methods as specified in IEC 529:1989.

IP (International Protection) Code

a coding system to indicate the degree of protection provided by an enclosure against access to hazardous parts, ingress of solid foreign objects, ingress of water and to give additional information in connection with such protection as specified in IEC 529:1989.

462

E!3CS-10 1995


SECTION 26: GRAPHICAL SYMBOLS

26.4

SYMBOLS

(1) Symbols for electrical installations and degree of protection provided by enclosures for electrical equipment (lighting fittings) shall be as indicated in Tables 26.1 and 26.2, respectively.

Table 26.1 Graphical symbols for electrical installations

SYMBOL

DESCRIPTION Line Systems Conductor, general

----J\f'-

Flexible conductor Identification of Installation Method

- -

Underground line Overhead line

,

Surface line

~

In/Under surfaceline Identification of Intended Application

----

Protective Conductor (PEl

_.-.

Signal line

-"-"

Telephone line

-

... _-.

Radio line Supply Lines

/

/

•

/

Wiring going upward Wiring going down Wiring oassing through vertically Junction of conductors for flush installation

Note: Darkened symbols indicate flush [recessed] installations.

'EBc$~ 10 1995


,'"

46~


Table 26.1 Graphical symbols for electrical Installations (conte'd) SYMBOL

DESCRIPTION Supply Lines (conte'd)

-- ~

--L

CJ

~ l..IIII

Junction of conductors for surface installations Earthing Surface mounted (central) main distribution board Flush mounted (central) main distribution board Surface mounted sub-distribution board Flush mounted sub-distribution board

Switchgear I--

OJ

Fuse, general

~

Three-pole fuse, general

t

Low voltage HRC fuse

(

r ~

~

~

Fuse disconnector Switch Automatic breaker for line protection Breaker with thermalover-current trip, e.g Motor circuit break-ef Star-delta Motor Starter

L:J

Direct-an-line starter

Switches used for installation purposes

t'/'

On-off switch, single-pole

r

On-off switch, double-pole

~

On-off switch, triple-pole

y

Two-ci rcuit switch, single interruption .

.f

Two-way switch, single-pole

@]

©

Push-button


464

EBCS-10 1995

ETHIOPIA~I

BUILDING CODE STANDARD

SECTION 26: GRAPHICAL-SYMBOLS

Table 26.1 Graphical symbols for electrical installations (conte'd)

SYMBOL

DESCRIPTION

Switches used for installation purposes (conte'd)

®

Push-button with indicator lamp

~

Dimmer switch

G)

Light-sensitive switch

(§)

Float switch

I}

Time switch

III

Current pulse switch

IT]

Time relay Socket Outlets

A.

Single-phase socket outlet

AL

single-phase socket outlet + PE

rh

Twin socket outlet

~ ~

Socket outlet with switch Three-phase socket outlet + PE

n

,

~n

Telephone socket outlet Antenna socket outlet

I

/\I

Empty box

I

Luminaires

I ~-NQte:

X

Luminaire general symbol

tx

Wall mounted luminaire

'A

Luminaire with switch

X

Emergency luminaire

ex

Flood Iight (Projector)

)(

I

Florescent luminaire single lamp "A':

Darkened symbols indicate flush [recessed] installations


i

EBCS-10 1995

l

465



SYMBOL

DESCRIPTION

Luminaires(conte'd)

I

I

x

Florescent luminaire double lamp

I

I

I

@

)(

I

Row of florescent luminaire Exterior luminaire (post top)

Indicating Instruments and Transformers

0009

Ind icati ng instruments

IKwhm

Metre (kilowatthour-metre)

0 -S-
Current transformer Voltage transformer Power Supply Units

U

Convertor General Symbol

~

Rectifier

-lr-

Battery (Cell)

0

Inverter Electrical Appliances (Power)

~ ~ ~

I~I

Electrical appliance, General symbol Kitchen appliance Electric range, general symbol Microwave cooker

t!j [@J

Hotplate

()t-

Water heater

r®]

Washing machine

Baking oven


466

EBCS~10

1995


SEcllON 26: GRAPHICAL SYMBOvO


SYMBOL

DESCRIPTION .....

.--'-_._.

Electrical Appliances(conte'd) I Clothes dryer

[1J ~

Dish washer

@

E!J ~ ,-***-] ® ®

_

fan Air conditioning .0"

Freezer ..

Deep freezer Motor

...

g

Generator Communication appliances Intercom

g

Telephone exchange, general symbol

[8:]11

Automatic Telephone exchange Signalling Devices

-D

Bell

D=7

Horn

=:j)

Siren

U

Call indicator panel (Number indicates call stations, for example 9 stations)

0

Electric Clock

®

Master Clock

II~I

Non-automatic fire alarm device (manual fire call point)

II=:=JI

Fire alarm control & indicating panel

[~l

Smoke detector


ETHIOPIAr'\1 BUILDING CODE STANDARD

EBCS-10 1995

467

----~---_._-------------------------------------------

ANNEX

A

(INFORMATIVE)

SYMBOLS ON LIGHT FITTINGS COMPLYING WITH IEC 598

Test marks

SYMBOL

DESCRIPTION

~

The VDE-test mark is the symbol of the association "Verein Deutscher Elektrotechiker" (= Association of German Electrical Engineers.) The approval is based on internationally specified rules. It certifies the successfully passed tests according to the safety regulations and the VDE-and the IEC-specifications. _.

W

Lighting fittings for discharge lamps with this sign are suitable for direct mounting on normal or easily inflammable materials, comply with DI N 4102, as far as their inflammation temperature is at least at 200°C, and if they remain stable and are not subject to deformation upto this temperature.

._-_.

1--

vw

Lighti ng fitti ngs suitable for mounti ng in fire-hazardous locations and prem ises (VDE 0100) proof) is at least required.

IP 50 (dust

Lighting fittings for discharge lamps for direct mounting on fixtures and furnitures, which conform in their behaviour for inflammation to hardly or normally inflammable materials, although if these materials being varnished, coated or veneered. .. r----------

W

_ . _ ~

W\7

_ ~ .

Lightingfittingssuitablefor mountingon materials with unknown inflammability.The procedure of mounting is specified.

-

-,

I

(@

Radio interference suppression according to VDE 0875. All lighting fittings conform to the interference suppression degree G. By using additional interference suppression device degree N will be reached.

-

@

Impact proof lighting fittings are suitable for gymnastic and sports premises. The tests are made according to DIN 18032 and VDE 0711.

470

EBCS-10 1995


--------,.

ANNEX

B

(INFORMATIVE) .

PROTECTION CLASSES

The light fittings are classified in three categories against electrical shocks depending on the type of protection,

DESCRIPTION

SYMBOL

®

Class I

Protective wire required -

The lighting fitting has protective

0

Class II

insulation, a protective therefore, not required,

wire

is,

.-._---

Class III

For Iighting fittings with incandescent lamps for connection to low voltage with protective insulation (Max. 42.0V). A protective wire

is not

allowed.

ETHIOPIAN BUILDING CODE--STANDARD

EBCS-10 1995

471

APPENDICES APPENDIX

1

INSPECTION AND TESTING

1

INITIAL VERIFICATION

1.1

General

(1) Every installation shall, during erection and/or on completion but before being put into service, be inspected and tested to verify; so far as is reasonably practicable, that the requirements Of this Electrical Installation Code have been met. (2) The method of test shall be such that no danger to persons, livestock or property or damage to equipment can occur even if the circuit tested is defective. 1.2

Inspection

(1) Detailed inspection shall precede testing and shall normally be carred out with that . portion of the installation under inspection being disconnected from the supply.

(2) The detailed inspection shall be made to verify that the installed electrical equipment is:

a) in compliance with this Electrical installation Code; b) correctly selected and erected in accordance with this Electrical Installation Code; and c) not visibly damaged or defective so as to impair safety. (3) The detailed inspection shall include at least the checking of the following items, where relevant to the installation, and, where necessary, during erection:


EBCS-10 1995

A-l

______________________

000_0

0_-

_

ELECTRICAL INSTALLATION OF BUILDINGS connection of conductors; identification of conductors; routing of cables in safe zones or mechanical protection; selection of conductors for current cariying capacity and voltage drop in accordance with the design; e) connection of single pole devices for protection or switching in phase conductors only; t) correct connection socket-outlets' and lampholders; g) presence of fire barriers and protection against thermal effects; h) methods of protection against direct contact (including measurement of distances, where appropriate); i.e., i) protection by insulation of live parts, ii) protection by barrier or enclosure, iii) protection by obstacles, iv) protection by placing out of reach; a) b) c) d)

i.

i)

methods of protection against indirect contact; i.e, i) presence of protective conductors, ii) presence of earthing conductors, iii) presence of main equipotential bonding conductors, .iv) earthing arrangements for combined protective and functional purposes, v) use of Class II equipment or equivalent insulation, vi) non-conducting location (including measurement of distances, where appropriate), vii) .earth-free local equipotential bonding, viii) electrical separation;

j) k) 1) m)

prevention of mutual detrimental influence; presence of appropriate devices for isolation and switching; presence of under-voltage protective devices; choice and setting of protective and monitoring devices (for protection against indirect contact and/or protection against overcurrent); n) labelling of circuits, fuses, switches and terminals; 0) selection of equipment and protective measures appropriate to external influences; p) adequacy of access to switchgear and equipment; q) presence of danger notices and other warning notices; r) presence of diagrams, instructions and similar information; s) erection methods.

A

m2

EBCS-10 1995


-~------------~---------------~

APPENDIX 1: INSPECTION AND JESTING

1.3

Testing

1.3.1 Tests lobe carried out (1) The following tests, where relevant, shall be carried out in that sequence. a) continuity of protective conductors i)

Every protective conductor shall be tested to verify that it is electrically sound and correctly connected.

b) continuity of ring final circuit conductors i)

A test shall be made to verify the continuity of each conductor, including the protective conductor, of every ring final circuit.

c) Insulation resistance i) ii)

iii)

iv)

v) vi)

The insulation resistance between live conductors shall be measured before the installation is connected to the supply. Particular attention shall be given to the presence of electronic devices connected in the installation and, where necessary, such devices shall be isolated _so that they are not damaged by the test voltage and thereafter tested in accordance with (vi) below. The insulation resistance shall also be measured between each live conductor and earth, the PEN conductor in TN-C systems being considered as- part of the earth. Where appropriate during this measurement, phase and neutral conductors may be connected together. The insulation resistance measured with the d.c. test voltages indicated in Table 1 shall be considered satisfactory if the main switchboard, and each distribution circuit tested separately with all its final circuits connected but with current-using equipment disconnected, has an insulation resistance not less than the value given in Table 1. The testing equipment shall be capable of supplying the test voltage indicated in Table A.l when loaded with LOrnA. Where equipment such as electronic devices are disconnected for the tests prescribed in a(i) through c (v) above and the equipment has exposed conductive parts to be connected to protective conductors, the insulation,


EBCS-10 1995

A-3


resistance between the exposed conductive parts and live parts of the disconnected equipment sha:I1 be measured separately and shall be not less than O.5mega Ohm. Table 1: Minimum values of insulation resistance

Circuit nominal voltage [V]

Test voltage d.c, [V]

Minimum insulation resistance (mega Ohms)

Extra-low voltage circuits when the circuit is supplied from a safety isolating transfortner

Z50

0.25

Up to and including 500.0V with the exception of the above cases

500

0.5

Above 500.0V up to 10OO.OV

1000

1.0

Between SELV circuits and associated LV circuits

500

5.0

Note:

i) In the event of any test indicating failure to comply with the requirmentsof clause [Ic) above, that test and those preceding it (the results of which may have been influenced by the indicated fault) "hall be repeated after the fault has been rectified. ii) Reference methods of test are described in Guidance Notes on the Wiring Regulations published by the Institution of Electrical Engineers (lEE); but the use of other methods giving no less effective results is not precluded.

d) Site applied insulation (i)

(ii)

Where insulation" applied on site is intended to provide protection against direct contact, it shall be verified that the insulation is capable of withstanding, without breakdown or flashover, an applied voltage test equivalent to that specified in the relevant acceptable Standard for similar type-tested equipment. Where protection against indirect contact is provided by supplementary insulation applied to equipment during erection, it shall be verified by test that: - the insulating enclosure affords a degree of protection not less than IP2X, and

A-4

EBCS-10 1995


APPENDIX 1: INSPECTION AND TESTING

- . the insulating enclosure is capable of withstanding, without breakdown or flashover, an applied voltage test equivalent to that specified in the relevant acceptable Standard for similar type tested equipment. e) Protection by separation of circuits (i)

(ii)

Where protection against electric shock is provided by SELV, it shall be verified by inspection and test. Where protection against electric shock is provided by electrical separation, it shall be verified by inspection and test.

f) protection against direct contact, by a barrier or enclosure provided during erection (i)

Where protection against direct contact is intended to be afforded by a barrier or enclosure provided during erection, it shall be verified by test that each enclosure or barrier affords a degree of protection not less than 1P2X or 1P4X as appropriate.

g) Insulation of non-conducting floors and walls (i)

Where protection against indirect contact is to be provided by a non conducting location, the resistance of the floors and walls of the location to the main protective conductor of the installation shall be measured at not less than three points on each relevant surface, one of which shall be not less than 1.0m and not more than 102m from any extraneous conductive part in the location. The other two measurements shall be made at greater distances .

.(ii)

Any insulation or insulating ". .angement of extraneous conductive parts: - when tested at 500.0V d.c, shall not be less than O.5mega ohm; - shall be able to withstand a test voltage of at least 2.0kV r.m.s, a.c. and - shall not pass a leakage 'current exceeding 1.0mA in normal conditions of use.

(h)

Polarity (i)

A test of polarity shall be made and it shall be verified that: - every fuse and single-pole control and protective device is connected in the phase conductor only;


EBC~-1

0 1995

A-5

ELECTRICAL INSTALLATION OF

4.3

8UILDI~GS

Alterations and Additions

(1) The requirements of Clause 4.2 for the issuance of a Completion & Inspection Certificate shall apply to all the work of the alterations or additions; any defects or omissions revealed in that work shall be made good before a Completion Report is issued. (2) The Contractor or other person responsible for the new work, or a person authorised to act on his behalf, shall report in writing to the person ordering the work any defects found in related parts of the existing installation.

A-8

EBCS-10 1995

ETHIOPIAhl BUILDING CODE STANDARD

APPENDIX 2: FORMS OF COMPLETION AND INSPECTION CERTIFICATE

APPENDIX

2

FORMS OF COMPLETION AND INSPECTION CERTIFICATE

1.

Installation

(1) The forms of completion, inspection and testing shall be made out and signed by competent persons in respect of the design, construction, inspection and testing of work. (2) Completed forms shall indicate a responsibility for design, construction, inspection and testing, whether in relation to new work or further work ·on an existing installation.


EBCS-10 1995

A-9

----

-----------------------

---------~

FORMS OF COMPLETION & INSPECfION CERTIFICATE DETAILS OF THE INSTALLATION

Client: Address: DESIGN I/We, being the person(s) responsible (as indicated by my/our signatures below) for the Design of the electrical installation, particulars of which are described on Page ... of this Form, CERTIFY that the said work for which I/we have been responsible is to the best of my/our knowledge and belief in accordance with the Regulations for Electrical . Installations published by except for the departures, if any, stated in this Certificate. The exterit of liability of the signatory is limited to the work described above as the subject this Certificate.

For the

DESIGN

of the installation: Position:

Name (in block letters):

Reg. No.

For and on behalf of: Address: (3) Date

(2) Signature: CONSTRUCTION

I/We, being the person/s) responsible (as indicated by my/our signature below) for theConstruction of the electrical installation, particulars of which are described on Page.... of this Form CERTIFY that the said work for which I/we have been responsible is to the best of my/our knowledge and felief in accordance with the Regulation for Electrical Installations published by except for the departures, if any, stated in this Certificate.

The extent of liability of the signatory is limited to the work described above as the subject of this Certificate. For the CONSTRUCTION of the installation: Position:


Reg. No.

For and on behalf of: Address: (2) Signature:

(3) Date:

INSPECTION AND TEST I/We, being the person(s) responsible (as indicated by my/our signatures below) for the Inspection and Test of the electrical installation, particulars of which are described on Page ... of this Form, CERTIFY that the said work for which I/we have been responsible is to the best of my/our knowledge and belief in accordance with the Regulations for Electrical Installations published by , except for departures, if any, stated in this Certificate.

The extent of liability of the signatory is limited to the work described above as the subject this Certificate. For the

INSPECTION AND TEST


of the installation:

Reg. No.

Position:

For and on behalf of: Address: I RECOMMEND

that this installation be further inspected and tested after an interval of not more than

.......... years. (2) Signature:

(3) Date:


NOTE: 1.

This document is intended for the initial certification of a new installation or of an alteration or addition to an existing installation and of an inspection.

2.

The-signatures appended are those of the persons authorized by the companies executing the work of dCllign,construction and Inspection and tcsttng respectively. A signatory authorized to certify more than one category of work shall sign in each of the appropriate places.

SCHEDULE OF ADDITIONAL RECORDS


EBCS-10 1995

A-11

PARTICULARS OF THE INSTALLATION (Delete or complete items as appropriate)

New/Alteration/Addition/ to existing installation

Type of Installation:

o

Type of Earthing:

TN-C

Earth Electrode:

0 TN"S

0 TN-CS

0 TI

Resistance

0 IT

................. ohms

Method of Measurement Type and Location

.

Characteristics of the supply at the origin of the installation: ............. Volts

Nominal voltage

............. Hz

Frequency Number of Phases

~

..

Prospective short-circuit current

................kA

Earth fault loop impedance (z.)

.................ohms

Overcurrent protective device:

Type

..

Rating .... A

Rating ..... A.

Main switch or circuit-breaker (if an r.c.d., rated residual operating current lAD

No of poles

mA.)

Method of earthing: 0 Cable sheath.

o o o o o

Additional overhead line conductor Protective multiple earthing (p.M.E.) Buried strip/rod/plate Earth-leakage circuit-breaker, voltage operated Earth-leakage circuit-breaker, current operated

The impedance of each earth-continuity conductor is satisfactory:

DYes

o

No

The total earth-loop impedance is 0 satisfactory 0 unsatisfactory for ready operation of the largest-rated excess-current protective device relied upon for earth-leakage protection. Earth-leakage protection is afforded by a 0 current-operated earth-leakage circuit-breaker, the operation of which is effective.

.

0 voltage-operated

..


Polarity throughout the installation is correct

DYes

All single-pole control devices are in live conductors only

DYes

o

o

No

No

The insulation resistance of the fixed wiring installation is not less than 1 megohm· DYes

o

No

The insulation resistance to earth of each item of apparatus tested separately is not less than 0.5 megao m. Each item of apparatus tested separately is in good serviceable condition, except as stated below. All flexible cords, switches, fuses, plugs and socket-outlets are in good serviceable condition, except as stated below: ..

There is no sign of overloading of conductors or accessories except as stated below.

Apparatus tested

CJ includes .

o

does not include

portable appliances.

Comments (if any) and departures from the WiriJ;lg Regulations:

Signed

Date:

.

For and on behalf of:

Address:


EBCS-10 1995

A-13

INDEX

A Accessibility 453

Air blower installation 459

Air conditioning 380

Alarm signals 346

Amhienttemperature 353

Audibility of general alarm 355

Audible alarms provided by public address equipment 356

Audio transformer 452

Automatic restarting after overload 264

Auxiliary equipment 326

Available short-circuit current 145

Avoidance offlue -like opening 358

B Ballast protection 327

Bends 376

Bonding 169,171,451

Bonding conductor size 450,457,458

Bonding medium 450

Box 361

Branch circuit loading and protection 333

Branch circuit overcurrent protection 260

c Capacity of protective gear 147

Car lighting and accessories 380

Ceiling 3~3

Ceiling outlet box wiring 325

Charging facility 360

Circuit c~nnection 360

Circuit segregation 455

Clothes closets 320

Colour coding 323

Colour rendering j 7

Common earth 430

. Communication conductors and cables not exceeding 750V 448

Component 459

Concrete - enclosed electrode 169

Conduit type 4~5

Conductor installation 375 .

Conductor cross section and Insulation 324

Conductor in building of combustible construction 357

Conductor on movable parts 324

Conductor run 376

Conductors 331

Conductors - two or more motors 258

Conductors attachment 331

Conductors cross section 357

Conductors operating at no more than 50 k.v. 448

Conductors to individual motors 257

Conduit seal 148

Conduit to drain 148

Connection of conductors 376

Connection of electrodes 171

Gonnection point 359

Connection to supply 400

Construction 374

Construction and requirements 348

Construction of messenger cable 333

Continuity of earthing and bonding conductors 171

Continuous duty 384

Control location 267

Control 327

Control required 266

Control switches 320

Controls 457

Controls location 456

Corrosion 192

Coverings 414

D Deck box installation 451

Deck boxes 451

Deep moist clay soil 191

Design 346

Detached building 147

Detector types 350

Discrimination 147

Disruptive electrical influence 358

Driving rode electrode 170

Dry. niche himinaire 453

E Earth electrode seal for use within a tanked structure 192

Earth fault circuit breaker location 457 .

Earth rod connection 190

Earth-fault circuit interrupter 362

Earth-leakage protection 146

Earthed control circuit 267

Earthing and bonding 144

Earthing conductor /.0 be run in a straight line 430

Earthing Conductors 430

Earthing electrode 430

Earthing of shields 414

Electric lifts 383

Enclosed or guarded live parts 144

Equipment 385

Equipment and power supply 346

Excess load 400

Explosive on flammable atmosphere 347

External metal 189

F Fault signal discrimination 347

Feeder conductors 259

Fceder overcurrent protect 261

Feeding 400

Field - assembled unit 458

Floor openings 353

Floor protective coverings 414

Flue-like openings 351

Forming shell types 454

. Fusing 360

G General 145,188,190,326,328,331,347,348,349,354,360,

373,397,413,448,449,450,452,454,456,457,458,356

Grouping 143

Grouping of motors on a single branch circuit 261

INDEX H Hazard 327

Heat barrier 354

Height consideration 351

Height of conductor 332

Highest voltage- 358

Hoistway door interlocking wiring 378

Hydraulic lifts 383

I

lIIuminance 37

Illumination level 387

In hoistway,machine rooms and escalator wellways 379

Independentmetal water pipes 168

Installation and bonding 458

Installation 357,375,400,454,458 Installation and type 148

Instanteneoustrip circuit interrupters 262

Insulation 429

Insulation rating 378

Insulation resistance 356

Intemal metal 189

Interruption 361

J Joints 189

Junction box bonding conductor 450

L Labelling 361

Lamp holders 326, 332

Lantern lights 351,353 Laying 170

Length of cable from transformers 376

Lighting 386

Lighting fixtures 292

Lighting fixtures 285,286, 288,290 Lighting switch 387

Lirnitsofspacing 352

Live parts 321

Location 145, 451,452 Location oflighting equipment 320

Location of the alarm contrast and indicating panel 346

Luminaire 387

Luminaire protection 453

Luminaire as a raceway 323

Luminaire construction 319

Luminaire exposedto flying objects 322

Luminaire in damp or wet location 320

Luminaire support 453

Luminaries 458

Mechanical and electrical requirements 188

Mechanical protection 430

Metal car frame supported by cables 385

Metal casing ofa pump 169

Metal parts 453

Meters instruments and relays 284

M~um height ofluminaries 322

Monitoring 350

,'Motor supply conductor insulation, temperature 257

285,286,237289,291,293

Motors and generators Motors and generators 285

Motors and generators 286




Multiple services 142

N Near or over combustible material 320

Non - continuous duty 384

Number and location of overload devices 263

Number 'Ofcircuit element 347

o Oncars 379

Open core - and soil type transformer 375

Origin of call indication 348

Other wiring 378

Other classes 454

Other factors 354

Outlet boxes to be covered 322

Outlet distance 400

Over current protection 146,327,362375

Over load and over heating protection 362

Overcurrent protection marked on equipment 260

Overheating protectionrequired 265

Overheating protectionrequired for motors 265

Overload protection not required 264

Overload protection required 262

p

Pendant conductors 324

Placement' 349

Plate electrode 170

Portable motors 257

Position relative to ceiling 351

Protection 452,456

Protection device location 380

Protection ofuninsulated part 374

Provision for bonding offuture equipment 189

Protection 319

Public water pipe 168

R M Manual call in automatic alarm 349

Marking 143,374

Material 318, 429

Material for bonding conductors 171

Material for system earthing 171

Means of disconnect 146

Rated duration of operation 38

Rating and ampacity 257

Rating or trip selectionof overload devices 263

Recessedluminaire 322

Recessed luminaire wiring 324

Reinforcing steel 449

Remote location 361

INDEX

Response time 311

Restricted alarms 355

Rod electrode 170

s Sandy or gravely soli 1'J I

Secondary conductors 259

Secondary voltage 374

Sectioned rooms 351

Segregation 358

.Segregation 397

Sequence of control 147

Service equipment 328

Shallow top soil 191

Short circuit protection 362

Show windows 320

Shunting of overload protection during starting 264

Silencing switch 355

Single service 142

Single truss and north-light roofs 353

Siting of safety luminaries in hazardous workspaces 38

Size of protective earth 430

Staircases 35 1

Socket outlet 387,458 Soilless than O.3m deeps 191

Spacing 170

Spacing and crossing 358

Spacing from combustible material 332

Spacing of conductors 332

Special monitoring 351

Split knobs 331

Starters having different sorting and running positions 267

Stationary motors 257

Storage - battery charging equipment 292

Stricken 349

Submersion depth 452

Suitability 357

Supply 456

Support 429

Supports 321

Switches, controllers, circuit breakers and fuses 87,289,290,293 Switches, motor controllers, circuit breakers and fuses 284

System heights 414

T Thermal protection 326

Thickness 374

Times switch 456

Transformer 326

Transformers and capacitors 284, 287,289,290, 293

Transformers used outdoors 375

Transmission circuitry 347

Travelling cables 378

Trouble signal 398

Two- stage alarm 355

Type of insulator 331

Types of conductors 376

Types of overheating protection 265

Types of overload protection 263

u Undervoltage protection on feeders or branch circuits 266

Undervoltage protection required for motors 265

Use of Insulators 331

Use ofmessenger cables Use permitted 413

Use prohibited 413

:tn

v

Ventilation 374

Visual alarm signal 356

Voltage 31'9,453

Voltage drop 399,400

w Warning sign 454

Wet niche or submersible luminaire 452

Wiring 399

Wiring methods 285,286,287,289,291,293

Wiring methods on poler 328

Wiring methods underground 328

Wiring oflighting equipment 323

wiring ofluminaries 323

Winne of show-window luminaries 325

Working space 145

EBCS-10.pdf

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