EBCS-10 Ethiopian Building Code Standard Electrical Installation of Buildings

EBCS-10

Ethiopian Building Code Standard

ELECTRICAL INSTALLATION OF BUILDINGS

FOREWORD The Proclamation to define 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 docum~nts 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

INTRODUCTION This Code Standard for the Electrical Installation of Buildings is part of the Building Code of Ethiopia: This Code Standard for the Electrical Instaijation of Buildings is mairily 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 number of foreign national and international standards. The Code embr~ces 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 (EELP A) • Addis Ababa University, Faculty of Technology (AAU) • Ethiopian Authority for Standardization (BAS).

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ETHIOPIAN BUILDING CODE STANDARD

EBCS-10 ELECTRICAL INSTALLATION OF BUilDINGS

TABLE OF CONTENTS Section 1 1.1 1.2 1J

Section 2 2.1

2.2

Scope And Definitions Scope Nonnative references Defmitions

1 1 2

Gen~ral Requirements Administrative

20

2.1.1 2.1.2

Authority for rules Pennit

2.1.3 2.1.4 2.1.5 2.1.6 2.1.7

Application for inspection Posting of penn it ', Notification re-inspection Plans and specifications Connection authorization

2.1.8 2.1.9 2.1.10 2.1.11 2.1.12 2.1.13 2.1.14

Re-inspection Renovation of existing installation Use of approved equipment Deviation or postponement Powers of rejection Installation of electrical equipment Damage and interfer•••.• ~e

i ••••••••••••••.••••••••••

i •••

,

20 20 20 20 20 21 21 21 21 22 22 22 22 22

Technical

23

2.2.1 2.2.2

Conventional symbols Co-ordination

'.'

2.2.3 2.2.4 2.2.5 2.2.6

Location and requirement of substation Rooms (spaces) required Location and requirements of distribution boards Location and requirements of PBX/PABX rooms

23 23 23 23 24 24

2.3

2.4

Section 3

Planning and designing 2.3:1 General

25 25

2.3.2 2.3.3

25 25

Marking of equipment 2.4.1 General

" ,

26 26

,

2.4.2

Workmanship and materials

27

2.4.3 2.4.4 2.4.5 2.4.6

Material for anchoring Protection of persons and property Maintainability , Enclosures

27 27 27 28

,. ,.

Illumination

3.1 3.2

Scope Normative references

3.3

Definitions

3.4

Lighting requirements 3.4.1 IllumiQance 3.4.2 Luminance 3.4.3 Glare' 3.4.4 3.4.5

29 29 ,

30 35 35 35 36

" '.. " '

Light direction and modelling Colour rendering

36 , .. , 36

3.5

Emergency lighting requirements 3 .5.1 Escape lighting 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,

38 38 39 39 39

3.7

II

Layout and installation drawing Design

3.6.5

Educational establishments

3.6.6

Hospitals

. ""

'

40

,

Outdoor lighting requirements 3.7.1 Illuminance

'

40

,

,

3.7.2

Colour r~ndering group

3,7.3 3.7.4

Limitation of glare : ' .' Lighting of outdoor fixed location work spaces

42 42 42 , 43 43

Se~tion 4

Conductors

4.1

Scope

4.2

Nonnative references

66

4.3

Definitions

67

4.4

Size of conductors

69

4.5

',' "

66.

4.4.1

Ph~e conductors in a.c. Circuits and live conductors in d.c. circuits ..

69

4.4.2

Neutral conductors

69

,

Ampacity of wires, cables and flexible cords

70

4.5.1

70

Conductor operating temperature

4.5.2 . Cables connected iri parallel

70

4.5.3

Cables connected to bare conductors or busbars

70

'4.5.4

Voltage drop

70

~

4.6

Flexible cords

4.7

Colour of conductors

"

4.8

Maximum permissible temperll,ture

'.'

:

70 71 71

Annex (preface)

74

Annex A (Normative) - Correction factors

85

Annex B (Normative) - Type of cable and ampacity

90

Section 5

Service And Service Equipment

5.i

Scope

5.2

Normative references

5.3

Definitions

5.4

General requirements

5.5

"

141

'.'

141 141

'

"

142

5.4.1

Number of services permitted

142

5.4.2 5.4.3 5.4.4

Consumer's installation not to be supplied through another building .conductors considered outside of a building Other' conductors in raceway or cable·

143 143 144

5.4.5

Clearance from building openings

144

Service equipment 5.5.1 General 5.5.2

Control

144 144 ·.. 145

III

5.6

5.7

Section 6

Wiring methods

148

5.6.1 5.6.2

148 148

Underground consumer's service conductors Overhead consumer's service conductors

Metering equipment 5.7.1 Connection

149 149

Circuit Loading and Demand Factor

6.1 6.2


150 150

6.3

Defmitions

150

6.4

General

151

6.5

Section 7

6.4.1

Current calculation

151

6.4.2 6.4.3 6.4.4

Voltage drop Maximum circuit loading Use of demand factor

151 151 151

Services and feeders

151

6.5.1

Single-family dwellings

151

6.5.2 6.5.3

Apartment and similar multi-family buildings Schools

6.5.4

Hospitals

153

6.5.5

Hotels, motels, dormitories, and buildings of similar occupancy

154

6.5.6 6.5.7

Other types of occupancy Branch circuits

155 155

6.5.8

Feeder demand factors for lifts

155

,

152 153

Earthing, Bonding, and Lightning Protection Part I - Earthing, and Bonding

IV

7.1 7.2


157 157

7.3

System and circuits earthing

158

7.3.1

Direct current. systems

158

7.3.2

Alternating - current systems

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 ., 7.4,5 Conductors to be earthed , , 7.4.6

7,6

7.8

,,

,

, .. 160

Bonding 7.5.1 Non-current carrying metal parts , , , 1.5.2 Exposed non-current-carrying metal parts of equipment •....... 7.5.3 Non-metallic wiring systems 7.5.4 Non-electrical services 7.5.5 Extraneous fixed metalwork

161 161 161 161 161 164

Method of earthing

164

7.6.1 7.6.2 7.6.3 7.6.4 7.6.5 7.6.6 7.7

Current over earthing conductor

159 159 159 1·59 160 160

,

,

Effective earthing Common earthing conductor Common earthing electrode Underground service Short section of raceway Fixed equipment

Bonding methods

,

_ , '. ,

, .. ", \. ,

166

7.7.1

Clean sUifaee

7.7.2 7.7.3 7.7.4

Bonding at service equipment ...........•.............. Means of assuring continuity at service equipment Metal annour or tape of service cable,

7.7.5 7.7.6 7.7.7

Bonding at other than service equipment Loosely jointed metal raceways Bonding jumpers

,

Earthing electrodes .. , 7.8.1 7.8.2 7.8.3

General, , Service pipe electrode, Artificial earthing electrodes

,,.,

164 164 164 165 165 ,. 165

166 166 167

, ,

,.,

, ,

,

166

167 167 167 168 168 168 169

v

7.9

7.10

Section 7

Earthing and bonding conduc;tors

171

7.9.1

General

171

7.9.2 7.9.3 7.9.4 7.9.5 7.9.6

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

172 173 174 174 174

Earthing and bonding conductor connections

175

7.10.1 7.10.2 7.10.3 7.10.4 7.10.5

175 175 175 176 176

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 Earthing conductor cQJ111Cction to electrodes

Earthing, Bonding and LightninlZProtection Part n- pghtning Protection

7.11 Scope 7.12 Normative references 7.13 Definitions 7.14 Materials 7.14.1 General 7.14.2 7.14.3 7.14.4 7.14.5 7.15 Form 7.15.1 7.15.2 7.15

J

7.16

..

Galvanic compatibility Corrosion protection Mechanical protection Use of aluminium

.'

178 178 179 180 180 180 181 181 181

,

and size Air termination Conductors Earth termination

184 184 185 185

7.15.4 Minimum dimension

185

Air termination 7.16.1 General

185 185

7.16.2 Support 7.16.3 Metallic projections 7.16.4 Metallic materials

185 185 186

7.16.5 Structure within zone .of protection ' 7.16.6 Air termination on roof 7.16.7 Air termination on reinforced concrete structure

186 186 186

VI

!

7.17

Down conductor

,

7,17.1 General

,

"

,

7.17.2 Routing 7,17.3 Recommended number

186

'

186 ,

187 187

,.,

7.17.4 Mechanical protection 7.17.5 Corrosive soil .....•............................... 7.17.6 External routes not available

187 187

,

7.17 .7 Lift shafts

, .. ,

,

,,. ,

7.17.8 Re-entrant loops . , Bonding to prevent side flashing Bonds

7.17.12

Testpoints

Earth termination

188 188 188

'

,

:

189

..........................•............

7.18.1 Termination, 7.18,2 Resistance to earth

7.19

188

,

7.17.10 7.1 7.11

190 , '

,

7.18.3 Earth electrodes.

,

7.18.4 Connection point

.. ,.".',

Common earthing

,

,

190 , . 190

,

, . , .. ,

, . , .. , ,

,

190 ,

:.,

190

,

7.19.1 Common earth potential

192

,

192

7.19.2 Common earth bonding

, . , . 192

7.20 Use of reinforcement for earthing in concrete Structures .. , .. : .. , 7.20.1 General, , , ,', . , . , , ,, 7.20.2 Electrical continuity . , . , -7.20.3 Prestressed concrete members 7.20.4 Precast concrete members 7.21

,, '

,

".,. 194 " . , . 194 194 194

'

, ,

,.,

193 193

, .. , , , .. , .. 193 193 "" .. , .. 193

,

Structural ~teel 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

187 188

'.'

7.17,9 Sharp bends

7.18

"

'

, 194 194

Annex (Informative) Annex A - System design Annex B - Consultation

, .. ,

219 220

VII

Section 8

Wiring Methods

8.1 8.2

Scope Normative reference

8.3

General requirements 8.3.1 Methods of-installatiOns 8.3.2 Wiring in ducts and plenum chambers 8.3.3 Underground installations 8.3.4 Conductors in hoistways

8.4

8.5

8.6

Conductors

8.9

223

223 224 224 225

,

······················

226

Types of conductors Radii of bends in conductors Conductor joints and splices

226 226 227

8.4.4

Supporting of conductors

228

Open wiring

228

8.5.1 Open and clipped direct 8.5.2 Spacing of conductors 8.5.3 Conductor supports

228 228 229

8.5.4

22?

Spacing of supports

Exposed wiring on exterior of buildings and between Buildings on the same premises

Location of conductors Clearance of conductors Power supply conductors

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 Cables, conductors and wiring methods

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

VIII

223 223

8.4.1 8.4.2 8.4.3

8.6.1 8.6.2 8.6.3 8.7 8.8

······················

,

229 229 229 229 230 230 230 231 231 ·231 232 233

Section

® 9.1 9.2

9.3

; 9.4

./I

Protection

and Control


'

237 237

General requirements 9.3.1 Protective and control devices

237 237

9.3.2

238

Types and ratings of protective and control devices

Protective devices

238

9.4.1

Overcu.rrent devices

238

9.4.2

Earth fault protection

239

9.5

Fuses

240

9.6

Circuit breakers

240

9.7

Control devices

240

9.8

Switches

241

9.9

Protection and control of miscellaneous apparatus

241

Section 10

Class 1 and Class 2 Circuits

10.1 Scope 10.2 Normative references 10.3 Classification

245 245' .10.

•••••••••••••••••••••

\

245

••••••••

10.3.1 General 10.3.2 Class 1 extra-low-voltage

245 power circuits

246

10.3.3 Class 2 low-energy power circuits 10.3.4 Hazardous location

246 246

10.3.5 Circuits to safety control devices 10.3.6 Circuits in communication cables

246 246

\

10.4 Class 1 circuits

247

10.4.1 Limitation of Class 1 circuits

247

10.4.2 Methods of installation for Class 1 circuits

247

10.4.3 Overcurrent protection of Class 1 circuits 10.4.4 Location of overcurrent devices in Class 1 circuits .;

247 247

10.4.5 Class I extra-low-voltage power circuit ~ources including Transfonners 10.4.6 Conductor material and sizes

. 248

248

10.4.7 Insulated conductors for Class 1 wiring "

248

10.4.8 Conductors of different circuits in the ,same enclosure, cable, or Raceway 10.4.9 Mechanical protection of remote-control circuits

248 249

10.4.10

249

Class 1 circuits extending aerially beyond a building

IX

10.5 Class 2 circuits 10.5.1 Limitations of Class 2 circuits

,

249 249

10.5.2 Methods of installation on supply side of overcurrent Transformers or other devices for Class 2 circuits

protection

10.5.3 Marking 10.5.4 Overcurrent protection for Class 2 circuits 10.5.5 Location of over current devices

or 250 250 250 251

'"

10.5.6 Conductors for Class 2 circuit wiring 251 10.5.7 Separation of Class 2 circuit conductors from other circuits 251 10.5.8 Conductors of different Class 2 circuits in the same cable, enclosure, or raceway 252 10.5.9 Penetration ofa fire separation 252 10.5.10 Conductors in vertical shafts and hoistways ; . 252 10.5.11 10.5.12

Class 2 conductors and equipment in ducts and plenum chambers .. 252 Equipment located on the load side of overcurrent protection, transformers, or current-limiting devices for Class 2 circuits , , , 252

10.5.13 10.5.14

Class 2 circuits extending beyond a building Underground installations ,

253 253

,

Section 11 Installation of Electrical Equipment 11.1 Scope 11.2 Normative references 11.3 General

254 254 , 254

, .. ,

11.3.1 Fusible equipment 11.3.2 Connection to identified terminals or leads 11.3.3 Equipment over combustible surfaces 11.3.4 Installation of ventilated enclosures 11.3.5 Outdoor installations 11.4 Electric heating and cooking appliances 11.4.1 Location of non-portable appliances 11.4.2 Rating of portable appliances 11.4.3 Appliance exceeding 1500w 11.5 Heatingequipment ; 11.6 Submersible pumps 11.7 Motors and associated ,circuits 11.7.1 11.7.2 11.7.3 11.7.4 11.7.5

Wiring methods and conductors Overcurrent protection Overload and overheating protection Undervoltage protection ~ Control

11.7.6 Disconnecting means

x

'

,

254 25~ ".

255 255 255 255 255 255 256 , 256 256 257 257 260 262 265 266 267

11.8 Air conditioning and refrigerating equipment 11.8.1 General

'.'

268 268

11.82 Branch circuit

268


269

11.8.4 Supply cords

,

269

11.9 Storage batteries

','

269

11.9.1 Location of storage batteries

269

11.9.2 Ventilation of battery rooms or areas

269

11.9.3 Battery vents

269

11.9.4 Battery instillatio~

'

269

11.9.5 Wiring

; .......•...

270

Section 12 Hazardous Locations 12.1 Scope 12.2 Nonnative reference 12.3 Classification

,

12.3.1 Division of Class I locations

;

279 279 279

...............•............

279

12.3.2 Division of Class II locations

280

12.3.3 Division of Class III locations

281

12.4 General requirements

281

12.4.1 Electrical equipment 12,.4.2 Marking .. "

281 282

12.4.J Non-essential electrical equipment

283

12.4.4 Equipment rooms

'

12.4.5 Cable trays

283 ; 284

12.5 Class I locations

284

12.5.1 Installations in Class I, Division 1 locations

284

. 12.5.2 Installat~ons in Class I, Division 2 locations

286

12.6 Class II locations

'.'

12.6.1 Installations in Class II, Division 1 locations 12.6.2 Installation in Class II, Division 2 locations ...............• 12.7 Class III locations

287 287 ~ 289 290

12.7.1 Installations in Class III, Division 1 locations

290

12.7.2 Installations in Class III; Division 2 locations

293

XI

Section 13 Fhimmable 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

294 295 295 295

13.3.2 Wiring and equipment within hazardous areas

296

13.3.3 Wiring and equipment above hazardous areas

297

13.4 Commercial garages, repairs and storage 13.4.1 Hazardous areas 13.4.2 Wiring and equipmentin

297 297

hazardous areas

298

13.4.3 Wiring above hazardous areas

298

13.4.4 EqUIpment above hazarqous areas

298

13.5 Residential storage garages 13.5.1 Non-hazardous location.

0

0

298 298

••••••••••••••••••••••••••••

13.5.2 Hazardous location . ;

299

13.5.3 Wiring

:

13.6 Bulk storage plants

299

'

299

13.6.1 , Hazardous areas

:

.

, ..

0

.'

299

•••••••••••••••••••••

13.6.2 Wiring and' eq~ipment in hazardol,ls areas 13.6.3 Wiring and equipment above hazardous areas 13.7 Finishing processes 13.7:1 Hazardous locations

302 302 302 302

0' ••••••••••••••••••••••••••••••••

,0

•••

·•..••

; •••••••.••.••••......

13.7.2 Wiring and' equipment in hazardous areas

304

13.7.3 Wiring and equipment aqove .hazardous areas 13.8 Aircraft; hangars .:. 13.8.1 Hazardous areas.. .. ... . 13.8.2 Wiring .and equipment in ,hazardous 'areas ... 13.8.3 Wiring not within' hazardous area. " '.' 13.8.4 Equipment-not within hazardous' areas 0

••••

0

0

••••••••••

.'

.'

o'

•••••

0

0

•••••

•••

0

'.

0

0

••

0

•••••••••

•••••••••••••••••

••

0.'

..

••••

0

•••••••••••••••••••

0

•

\

•

,

'0'

' •••••••••••••

o.

0

:

0 ••••••••••

•••••••••••••

305 305 305 306 306 307

Section 14' Patient Care' Areas 14.1 Scope· , 14.2 Nonnative references 0

XII

•••

' •••••

,;

'

••••••••••

:

,

••••

0

,

•••••••••••••

308 308

14.3 Definitions

308'

14.4 Circuits in basic care areas

31

14.4.1 Branch circuits

'...•..

14.4.2 Bonding to earth in basic-care areas '

'.' .:

'

14.5 Circuits in intermediate and critical-care areas

313

14.5.2 Bonding to earth in intermediate and critical-care areas 14.5.3 Receptacles in intermediate-and critical-care areas 14.6 Isolated systems

'.'

'

14.6.1 Sources of supply 14.6.2 Single-phase isolated circuits

14.7 Essential electrical systems

313 313 314

"

, ,

14.6.3 Three-phase isolated systems

314 314

:

\

315

'

315

14.7.1 Circuits in essential electrical systems .. ,\

Section

312 313

14.5.1 Branch circuits

14.9 Emergency supply

311 ,311

14.4.3 Socket outlets in basic-care areas

14.8 Transfer switches

~

315

,'

316 ,

316

15 Installation of Lighting Equipment 15.1 Scope

:

15.2 Normative references 15.3 Interior lighting :quipment : 15.3.1 General '

"

3 18

, . :.' .. '.' . "

'.'

318

, . '.. ~.~.. ,

318 318

..........•..............

320

'

15.3.2 Location of lighting equipment· 15.3.3 Installation. of ligpting equipment 15.3.4 Wirin~ of lighting. equipment

' .'

323

~

323

15.3.5 Earthing of-lighting equipment :." 15.3.6 Electric-discharge lighting systems operating at 1000V or less ·15.4 q~tdoor lighting equipment 15..4.1 General,

'.' .,

,

:

15.4.2: Permanent outdoor floodlighting installation 1,5.4.3 'Exposedwirin~ for permanent outdoor lighting Annex A (Normative) .'

i

; .. ,

;

326 326 327 327 328 331 334

XIII

Section 16 Fire Alarm System and Fire. Pumps 16.1 Scope , , 16.2 Normative references 16.3 Definitions

'

",.,

16.4 Design consideration , 16.4.1 General ,

,:,.

~ ,

, -,'

.. , ,

,, ., ~

.

16.4.2·
,.,

16.4.3 Manual call points

.,

.. ,

,

,

344 344

, . , .....•...

, , .. : , .. , . , ,

, ,,

, .. , ,

,' 344 346 . 346· .

,

,

,

347

-

,

,

, .. , . .'.,

348,'

16.4.4 Selection of fITe detectors , ': , , .. , -. , 349 16.4.5 Sitting of detectors ,."" .. ,." .. '., '.' 350 16.4.6 Sitting of heat' sensitive (point) detectors, .... , .. , '. , , . , '. , , . , , 35

i

16.4.7 Vibration combined with rapid temperature change .. '.'

, , , .. 353

16.4.8 Sitting ofheat-sensitive.(line) detectors. , . , .... , ., , ; " .. ~54 16.4.9 Sitting of smoke-sensitive detectors ... ,.,.".,.:.""., .• 354 16.4.10 Audible and visual alarms , .,,, ., , . , . , , .. , . 354

16.5 Cables and wiring .,' .. ,.,., 16,5.1 Cables" ,-.. ,-.,.,

,.,

16.5.2 Wiring method .. , . , . , 16.6 Equipment bonding ....

, ...

', .. , , .. ,

, . .-,,.,

,

, ,,·356_ 356

, ,. , , ,.,

, , , , 357

, , , .. , , .. , .. .' . , .. ,

16.6.1 Exposed non-current carrying'metal P¥t 16.6.2 Bonding conductor .. , .,

, ,

,.. ,."

.. ,

,

,

16.7.2 Sources of power . ,

-, . , , .. ,.,

16.8.2 Wiring method

, .,., ,

,

,

, ,

, , . , .. , . , . ,

_Annex B (Informative)

XIV

.. 35~, 359

,

359

, .. , , ,

,

359, 360

,

16.8,3 Consumers' service mr fire pumps 16.8.4 Protection , , Annex A (Informative)

, .,

. , 359, 359

, .. .' . ,

16.7.3 Current supply 16..8 Fire pumps 16.8.1 Conductors

, ,', .. ",

16.7 Power supply system .. , 16.7.1 Operating voltage,

, , , . ",

'. , . , , . , . , , .. , ,. ,

361 361

, ,

, , . , .. , , .. ,., ,

, .. , , , , . , , 361 .. , 362 ,.,.

,

361

363 , . 365

'.

,

'

Section 17 Signs and Outline Lighting ..17.1 "' Scope· 17.2 Normative references

'

371 371

17.3 General requirements

371

17.3 .1' Construction

371


372

17.3.3 Rating of.disconnecting means and control devices 17.3.4 Thermal protection '

3 /2 372

17.3.5 Branch. circuit capacity

372

'

17.3.6 Location

,': .'. :

17.3.7 Bonding

'

17.3.8 Protection of sign leads 17.3.9 Installation of conductors 17.3.10

372

'

373

' :'

'

Fuseholders and flashers

'.' :

.

'

'

373

17.4 High-voltage luminous discharge tube signs and outline Lighting 17.4.1 Enclosure

.'

'

373

~ . '.. : .. '.: .. ,

17.4.2 Protection of uninsulat.edpart 17.4.3 Transformers

; .. 373

:

,

:

17.4.4 High-voltage wiring methods

373 373

'

374 : .. 374 375

'.<

Section 18 Lifts, Escalators and Similar Equipment 18.1 Scope : .. ~ 18.2 Normative references

"

.' . '.'

18.3 General 18.3.1 Voltage limitation 18.3.2 Live parts enclosed,: 18..4 Conductors

'

,".. ,

:

:

,,'''

:

"

:

:

377 377 377

3i7

' '

, ,

'

377 378

18.4.1 Installation of conductors 18.4.2 Minimum size of conductors

378 378

18.4.3 Motor circuit conductors

379

18.5 Wiring 18.5.1 Wiring methods

:

18.5.2 Branch circuits for auxiliary systems

379 379 380

xv

18.6 Installation of conductors 18.6.1 Number of conductors in raceway

' ~

18.6.2 Supports 18.6.3 Different systems in one raceway or travelling cable

,

18.6.4 Wiring in hoistway 18.6.5 Electric equipment in garages and similar occupancies 18.6.6 Sidewalk lifts 18.7 Travelling cables " 18.7.1 Suspension

380 380 381 381 381 381

~,_

381

18.7.2 Hazardousjclassified) location 18.7.3 Protection against damage

382 382

18.7.4 Installation

382

18.8 Disconnecting means and control 18.8.1 General

················

18.8.2 Type 18.8.3 Location

: ,

383

18.9 Overcurrent protection .. ~ 18.9.1 Control and opet~lting circuits 18.9.2 Motors 18.10

Machine room 18.10.1 18.10.2

382 382 383 383

\

18.8.4 Phase protection

; 383 383 384

;

384

Guarding equipment Clearance around control panels and disconnecting means

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 Overspeedprotection 18.12.2 Motor-generator overspeed device

385 385 386

18.13

Emergency power 18.13.1 Supply 18.13.2 Disconnection 18.13.3

XVI

380 380

Hydraulic lifts disconnecting means

·················

386 386 386 386

18.14

Machine rooms and hoistway pits lighting and Auxiliary 18.14.1 Machine room

386 386

llU4.2

387

Hoist pits

Section 19 Theatrelnstallation 19.1 Scope 19.2 Normative references

; 388 388

19.3 Wiring method 19.4

Fixed stage switchboard 19.4.1 Fuses

388 '

19.4.2 Overcurrent protection 19.4.3 Dimmers

389 389 ::

19.4-4 Control of stage and gallery pockets 19.4.5 Conductors

389 390 :

390 390

19.5 Portable switchboard on stage

391

19.5.1 Construction of portable switchboards

391

19.5.2 Supply for portable switchboard

391

19.6 Fixed stage equipment

391

19.6.1 Footlights 19.6.2 Metal work

391 391

19.6.3 Clearance at terminals

392

19.6.4 Mechanical protection of lamps in borders, etc 19.6.5 Suspended fixtures 19.6.6 Connections at lampholders

392 392 392

19.6.7 Ventilationfor mogullampholers, ~ 19.6.8 Conductor insulation for field-assembled fixtures

392 392

19.6.9 Branch circuit overcurrenf protection 19.6.10 Pendant lights rated more than lOOW 19.6.11 Cables for border lights 19.6.12 Wiring to arc pockets 19.6.13 Socket outlets and plugs 19.6.14 Curtain motors

392 393 393 393 393 394

19.6.15

394

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 fr?m portable equipment 19.7.4 Portable equipment for stage effects

-

394 394 395 395 395

XVII

~_.

Section 20 Emergency Systems, Unit Equipment, and Exit Signs 20.1 Scope 20.2 Normative reference

396 396

20.3 General

396

20.4

20.5

20.3.1 Adequate capacity 20.3.2 Instruction

396 397

20.3.3 Batteries maintenance

397

20.3.4 Lamps 20.3.5 Circuits

397 397

20.3.6 Method of wiring

397

Emergency systems

398

20.4.1 Supply 20.4.2 Control

398 398

20.4.3 Overcurrent protection

398

20.4.4 Audible and visual trouble-signal devices

398

Unit equipment

399

20.5.1 Mounting

20.6

,.. '

399

20.5.2 Supply connections

400

Exit signs

401

20.6.1 Power supply

40 I

20.6.2 Wiring

401

Section 21 Motion Picture Studios, Projection Rooms, Film Exchanges and Factory 21.1 Scope 21.2 Normative references

402 402

21.3

General

402

21.3.1 Wiring method

402

21.4

Viewing, cutting and patching table fixture

403

21.5

Film-vaults and storage rooms

403

21.5.1 Equipment in film vaults and storage rooms

403

21.5.2 Wiring method in film-vaults

403

21.5.3 Lighting fixtures in film-vaults 21.5.4 Film-vault circuits

403 404

XVIII

------

~I

21.6 Motion picture projection rooms ..

404

i •••••••••••••••••••••••••••

21.6.1 Lamps in projection rooms

404

21.6.2 Arc lamp current supply 21.6.3 Ventilation

404 404

21.7 Motors and generators

404

Section 22 Diagnostic Imaging Installation 22.1 Scope 22.2 Nonnative references 22.3 Definitions

"

405 405 405

22.4 High-voltage guarding

406

22.5 Connections to supply circuit

406

22.6 Disconnecting means

406

22.7 Transfonners and capacitors 22.8 Control

;

407 407

22.9 Ampacity of supply conductors and rating of overclirrent protection

408

22.10

408

Bonding

Section 23 Electrical Communication

Systems

23.1 Scope 23:2 Nonnative reference 23.3 General

-

409 409 409

23.3.1 Circuits in communication cables

409

23.3.2 Hazardous locations

410

23.3.3 Approved transfonners

410

23.4 Inside conductors

410

23.4.1 Conductors arrangement 23.4.2 Insulation

410 410

23.4.3 Earthing conductors with an outer metal covering

410

23.4.4 Separation from other conductors

410

23.4.5 Penetration of a fire separation

411

23.4.6 Communication cable in hoistways

411

23.4.7 Communication conductors in ducts and plenum chambers

4.12

23.4.8 Data processing systems 23.4.9 Conductors under raised floors 23.4.10 Conductors in concealed installations

412 412 412

23.4.11

Type CFC under-carpet wiring system

_

413

XIX

23.5

23.6

23.7

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 23.5.4 Earth circuits

: 415 415

23.5.5 Communication systems in hospitals

415

Outside conductors

415

23.6.1 Overhead conductors on poles 23.6.2 Overhead conductor$ on roofs

415 415

~

23.6.3 Lightning conductors

416

23.6.4 Swimming pools

416

Underground circuits 23.7.1 Direct buried systems

"

l . 416

; 416

23.7.2 Underground raceway

'~

417

23.8' Earthing

417

23.8.1 Bonding of cable sheath

."

:

23.8.2 Cable-sheath bonding conductor

417 -

23.8.3 Earthing electrode

'.. 418

23.8A Earthing electrode connection 23.8.5 Bonding of electrodes

Section 24.. Community . 24.1 24.2 24.3

24.4

24.5

Antenna Installation

A18

:

419 419

For Radio And television Reception

Scope ",: :.~ Normative references'.:

420. 420

Technical requirements' 24.3.1 Mechanical·

421 421

24.3.2 Electrical

421

Equipment 24.4.1 Community antenna distribution amplifiers and other power sources

421 . 421

24.4.2 Exposed equipment and terminations

422

24.4.3 Equipment earthing

422

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 Supports 24.5.5 Earthing of outer conductive shield'of a coaxial cable

423 423

24.5.6 Earthing conductor 24.5.7 Earthing electrode

423 424

24.5.8 Earthing electrode connection

424

24.6 Conductors within buildings ~ ; 24.6.1 Separation from other.~onductors '" ..• ; 24.6.2 Conductors ina vertical shaft .. ; . ; .......•......... 24.6.3' Penetration of aJire separation

;' ,

:

'

42~ ; .424 425 426

''24.6.4 Commuriityantenna distributionconductorsin ducts and plenum Cambers .. 426' 24.6.5 Raceways ' '.' .............•..... 426 24.7 Conductors outside of buildings 24.7.1 Overhead conductors on poles 24.7.2 Overhead conductors on roofs 24.7.3 Conductors on buildings

:

"

;

..................•...........

426

24.7.4 Conductors entering buildings

427

24.7.5 Swimming pools

'

24.8 Underground conductors . 24.8.1 Direct buried systems

426 426 . ',' 426

'. 427

, .•......................... ' ;

'~

24.8.2 Underground raceway ................•.•............. . 24.8.3 . Underground bluck dIstribution

427 427 428 429

24.9 Lightning arresters for receiving stations

429

24.9.1 Lightning arrester .,

429

24.94

429

Earthing conductor

.24.9.3 Earthing electrode

430

Annex A (Informative)

431 ---

Section 25 Swimming Pools,· Fountains and Similar Installations 25.1 Scope 25.2 Normative reference

' '

446 446

25.3

Definitions

446

25.4

General

447

25.4.1 Equipment installation

447

25.4.2 Overhead wiring

448

25.4.3 Underground wiring

448

XXI

25.5

25.6

25.4.4 Bonding to earth 25.4.5 Junction and deck boxes

449 450

25.4.6 Transformers and transformer enclosure

451

25.4.7 Socket outlets

452

25.4.8 Luminaries and lighting equipment 25.4.9 Earth-fault circuit breakers

452 454

Permanently installed swimming pools 25.5.1 General

455 455

25.5.2 Conduit type

455

25.5.3 Circuit segregation

455

25.5.4 Drainage

455

Storable swimming pools

455

25.6.1 Electrical equipment

455

25.6.2 Pumps 25.7

25.8

'

456

Hydromassage bathtub 25.7.1 Protection

456 456

25.7.2 Control

456

25.7.3 Other electric equipment

457

Spas and hot tubs 25.8.1 Bonding to earth

457 457

25.8.2 Controls and other electrical equipment

457

25.8.3 Leakage current 25.8.4 Field-assembled units

~

458 458

Annex A (Informative)

Section 26

XXII

460

Graphical Symbols

26.1 26.2


26.3

Definitions

462 462 ···········

462

26.4 Symbols

463

Annex A - (Infonnative)

470

Annex B - (Infonnative)

471

Appendices

Appendix I Inspection and testing

A-I

Appendix 2 Fonns of completion and inspection certificate

A-9

XXIII

ECTION

1

SCOPE AND DEFINITIONS

1.1

SCOPE

(1) This Code applies to the design, selection, erection, ~nspection 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 lOOO.OY a.c. or

I500.0Y

d.c.

(2) This Code does not apply to: a) electric traction equipment, b) electrical equipment of automobiles, c) electrical equipment on board ships, d) electrical equipment in aircraft, e) public street-lighting installations, f) installations in mines, g) radio interference installation,

suppression equipment, except so far as it affects safety of the

h) fixed wiring for telecommunication,

signalling, control and the like,

i) internal wiring- of apparatus, j)

systems for distribution of energy to the public, or power generation and transmission for such systems.

1.2

NORMATIVE REFERENCES

(I) 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

1

EBCS-10 1995

Electrical Installations Definitions.

of Building,

Part 1, Scope, Object and



b) lEC 50:1982

International Electrotechnical Vocabulary.

c) BS 7671:1992

Requirements for Electrical Installations, lEE Wiring Regulations, Sixteenth Edition.

d) C 22.1:1992

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

(2) At the time of publication of this Building Code Standard, the editions indicated were valid. All references are subject to revisions, and parties to agreement and based on this Ethiopian Building Code Standard are encouraged to investigate the possibility of applying the most recent editions of the references

indicated below.

The Ethiopian Authority for Standardization

maintains registers of a number of foreign national and international standards.

1.3

DEFINITIONS

(1) For the purpose of this Code, the following definitions shall apply. acceptable accessible (as applied to wiring methods)

acceptable to the Authority enforcing this Code. not permanently closed in by the structure or finish of the building and capable of being removed without disturbing the building structure or finish.

. accessory

a device, other than current-using equipment, associated with such equipment or with the wiring of an installation.

ambient temperature

the temperature of the air or other medium where the equipment is to be used.

ampacity

a steady value of current which can be carried by a conductor

under specified conditions

without its steady state temperature exceeding a specified value.


EBCS-10 1995

2

SECTION 1: SCOPE AND DEFINITIONS

appliance

an item of current-using equipment other than a luminaire or an independent motor.

arms's reach

a zone of accessibility to touch, extending from any point on a surface where persons usually stand or move about, to the limits which a person can reach with his hand in any direction without assistance.

barrier

a part providing a defined degree of protection against contact with live parts, from any usual direction of access.

basic insulation

insulation applied to live parts to provide basic protection against electric shock and exclusively for functional purposes.

bonding conductor

a protective conductor providing equipotential bonding.

branch circuit

that portion of the wiring installation

between the final

overcurrent device protecting the circuit and the outlet(s). building void, accessible

a space within the structure or the components of a building accessible only at certain points.

building void, non-accessible

a space within a structure or the components of a building which has no ready means of access.

( )

bunched cables

cables are said to be bunched when two or more are contained within a single conduit, duct, ducting, or trunking or, if not enclosed, are not separated from each other by a specified distance.

bus

a conductor which serves as a common connection for the corresponding conductors of two or more circuits.

busway

.a raceway -consisting of metal troughing (including elbows, tees, crosses, in addifion to straight runs) containing conductors, the conductors being supported on insulators.

3

EBCS-10 1995



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-1 0 1995



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 connected to terminations. See fuse link.

circuit

and

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

circuit-breaker

a device capable of making, carrying and breaking normal load currents and also making and automatically breaking, under predetermined

conditions,

currents such as short-circuit currents.

abnormal

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-1 0 1995

5

ELECTRICAL INSTALLAtiON OF eUILDINGS

Class II equipment

'equipment in which protection against electric shock does not rely on basic insulation only, but in which additional safety precautions

such as supplementary J

insulation ate provided, there being no provision for the connection of exposed metalwork of the equipment to a

protective

conductor,

and

no

refianc-e

upon

precautions to be taken in the fixed wiring of the installation.

conduit

a part of a closed wiring system for cables in electrical installati()fis, allowing them to be drawn in and/or replaced, but not inserted laterally.

cutren/-permit

a written petrfiission from Authority having jurisdiction to a supply authority to the effect that electric energy may be supplied to a particular installation.

conneC/or

the part of a cable coupler or of an appliance coupler which is prOVided with female contacts and is intended to be attached to the end of the flexible cable remote from the supply.

contractor

any person who as principal,

servant or agent, by

himself or his 'associates, employees, servants or agents perfOIinS or engages to perform either for his own use and berrefit Or for that of 'another and for o-r without remunefation

or gain any work with respect to any

electrical installation or any other work to which this Code applies. current-carrying

capacity of a conductor

the maximum

current which can be carned

by a

cowductot under specified conditions without its steady state temperature exceeding a specified value.

cu"ent-usmg

6

equipment

EBCS-10 1995

equipment which converfs electrical energy into another form of energy, such as light, heat, or motive power.


SECTIQN 1: SCQPE AND DEFINITIONS

danger

risk of injury to persons (and livestock where expected to be present) from: a)

fire, electric shock, and bums arising from the use of electrical

b)

energy; mechanical movement of electric~lly controlled equipment, in so far as such danger is intended to be prevented by electrical emergency switching or by ~lectrical ~witching for mechanical maintenance of nop-electrical parts of such equipment.

design c14rrent (of a circuit)

the magnitude of the current (r.m.s. valll,e for a.c.) to be carried by the circuit in normal service.

direct contact

contact of perSOnSor livestock with live parts which may result in electric shock.

distribution board

an assembly containing switching or prote~tive devices (e.g. fuses or circuit-breakers) associated with one or more outgoing circuits fed from one or more incoming circuits, together with tenninals for the neutral arid protective circuit conductors. signalling and other control devices.

it may also include

Means of isolation may be

includ~d in the board Qr may be provided s~parately. distribution circuit

circuit cQnn~cting the origin of the installation to: a) an item of switchgear, b) an item of controlgear, or c) a distribution board to which one or more final circuits or items of current usmg equipment are connected.

(~ee also final circuit.)

A distribution circuit may also connect the origin of an installation to an outlying building or separate sometimes called a sub-main. double insulation

insulation comprising insulation.


installation,

when

it is

both basic insulation and supp'lementary

EBCS-1 0 1995

7


duct

a closed passageway formed underground or in a structure and intende~ to receive one or more cables which may be drawn in.

ducting

(see cable ducting)

earth

the conductive mass of the Earth, whose electric potential at any point is conventionally taken as zero.

earth electrode

a conductor or group of conductors in intimate contact with, and providing an electrical connection to, earth.

earth electrode resistance earth-fault

current

earth-fault loop impedance

the resistance of an earth electrode to earth. a fault current which flows to earth. the impedance of the earth-fault current loop starting and ending at the point of earth fault.

The earth fault loop comprises the

followiBg, starting at the point of fault: (a) the circuit protective

conductor;

(b) the consumer's earthing terminal and earthing conductor; (c) the earth return path; (d) the path through the earthen neutral point of the transformer and the transformer winding; and the phase conduCtor from the transformer to the point of fault. earth-leakage

current

a current which flows to extraneous-conductive-parts, which is electrically sound. component capacitors.

earthen equipotential zone

in a circuit

This current may have a capacitive

including that resulting from the deliberate use of

a zone within which exposed-conductive-parts

and extraneous-

conductive-parts are maintained at substantially the same potential by bonding, such that, under fault conditions, the differences in potential between simultaneously accessible exposed extraneous-conductive-parts will not cause electric shock. earthing

8

and

the act of connecting the exposed-conductive parts of an installation to the main earthing terminal of an installation.


EBCS-10 1995

--

--

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


earthing conductor

a protective conductor connecting the main earthing terminal of an installation to an earth electrode or to other means of earthing.

electric shock

a dangerous physiological effect resulting from the passing of an electric current through a human body or livestock.

electrical equipment

any item

for such purposes

as generation,

conversion,

transmission, distribution or utilization of electrical energy, such

as

machines,

transformers,

apparatus,

measuring

instruments, protective devices, wiring materials, accessories, appliances and luminaries. electrical installation

an assembly of associated electrical equipment supplied from a common origin to fulfil a specific purpose and having certain coordinated characteristics.

electrically independent

earth electrodes

earth electrodes located at such a distance from one another that the maximum current likely to flow through one of them does not significantly affect the potential of the other(s).

) electrode boUer, electrode water heater

equipment for the electrical heating of water or electrolyte by the passage of an electric current between electrodes immersed in the water or electrolyte.

emergency stopping

emergency switching intended to stop a dangerous movement.

emergency switching

rapid cutting off of electrical energy to remove any unexpected hazard to persons, livestock, or property.

enclosure

a part providing

an appropriate

degree of protection

of

equipment against certain external influences and a defined degree of protection against contact with live parts from any direction. equipment (abbr., see electrical equipment).


EBCS-1 0 1995

9


equipotential bonding

electrical connection maintainirig 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.

external influence

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 an abnormal or unintended path. This may result from an insulation failure or the bridging of insulation. Conventionally the impedance between live conductors or between live conductors and exposed or extraneousconductive-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 socket-outlet

or socket-outlets

equipment, or to a

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



funcJionaJ earthing

.

connection to earth necessary for proper functioning of electrical equipment.

functional extra-Iow volt4ge

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 ther current when this exceeds a give~ 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 lin~

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.

hot air sauna

a room or location in which air is heated to a high temperature and in which the rekrtive 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 ~very source of electrical energy.

isoilltor

a mechanical switching device which provides the function of isolation.

ladder (see cable ladder)

ETHIOPIANBUILDING CODE STANDARD

EBCS-10 1995

11


live part

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

luminaire

bquipment which distributes, filters, or transfonns 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 mecl1a.n-malsupport for a lu.minaire and the electrical connection to and disconnection from a fixed wiring installation. 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 tenninal

or bar provided for the CC/lili".:tlOnof

}lrotective conductors, including equipotential bonding conductors, and conductors for functional earthing if any, to the means of earthing.

mechanical maintenance

the replacement, refurbishment and non-electrical

parts

or cleaning of lamps

of equipment,

plant

and

machinery.

EBCS-1 0 1995



neutral conductor

a conductor

connected to the neutral point of a system and

contributing' to the transmission of electrical energy. 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-carryingcapacity.

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) exposed conductive parts (b) extraneous conductive parts (c) the main earthing terminal (d) earth electrode(s) (e) 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 110.0V ahd the nominal phase to earth 'voltage does not exceed 63.5V.

reinforced insulation

. 14

EBCS-10 1995

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



4

c

B

p

z

Figure 1.1 Enmple of earthing arrangements 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)

residual current

B M C P T

Main earthing terminal Exposed ·conductive part Extraneous conductive part Main metallic water pipe Earth electrode

E

Other means of earthing

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 upet'atlng current

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

ETHIOPIAN BUIL.DING 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 limited.

ring final circuit

of preventing

this contact is

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.

1iLV

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

ETHIOPIAN BUILDING"CODESTANDARD


Simultaneously

accessible parts may be

Live parts, eXPQsed-

conductive-parts, extraneous-conductive-parts, conductors, or earth electrodes.

protective

a device, provided with female contacts, which is intended to be

socket-ouNet

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

independent insulation applied in addition to basic insulation in

insulation

order to provide protection against electric shock in the event of a failure· of basic insulation.

supply authority

any municipal supplying

corporation,

electrical

power

commission, or energy

company intended

or person 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 of which are so arranged as to make or break all poles simultaneously or in a definite sequence.

switchboard

an assembly of switchgear with or without instruments, but the term does not apply to groups of local switches in final 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 ihdependent of the earth electrodes of the.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 of nominal voltage (r;m.s. values for a.c.) are defined: extra-low: Normally not exceeding 50.0Y a.'C. or 120.0Y ripple free d.c., whether between conductors or to earth, low:

Normally

exceeding

extra-low

voltage

but

not

exceeding

lOOO.OY a.c. or 1500.0Y d.c. between

conductors,- or 600.0Y a.c. or 900.0Y d.c. between conductors and earth. The actual voltage of the installation may differ from the nominal value by a quantity within normal tolerance.

E

18

EBCS-10 1995



SOURCE OF ENERJi

1I L2 L3

~ CONSUMERS

J'~'~\.-------,

rI

SOURCE EARlH

I I

, I

I

,

L

_

INSlALLAlI~

I

I I I

, I

,

•I ,I

I EQUf'tolENl IN INStALLAllON -

I.

I

I

I

,

,

1

EXPOSED

.J

CONDUCTJV

PARlS __

fAR1H

INSlAUAllOi fARlH ELCCTROfl:

ELE:ClROOE

Figure 1.2 TT System voltage reduced

wiring system.

(see reduced low voltage system). an assembly made up of cable or busbars and parts which secure and, if necessary, enclose the cable or busbars.

ETHIOPIAN

BUILDING CODE STANDARD

EBCS-10 1995

19

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 (1) Electric~l 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 with the Authority having jurisdiction on a form provided by the latter at the time the permit is obtained;

2.1.4 Posting oCPermit (1) A copy of the permit shall be posted in a conspicuous place on the site of the work and shall not be removed until the inspection is completed.

2.1.5 Notification Re-inspection (1) The Authority having jurisdiction shall be notified in writing by the electrical contractor ~at 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 (I) 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 reconnect 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 authorizatioft 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 suc~ 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-1 0 1995

21


2.1.10 Use of Approved Equipment (1) No one shall use any electrical equipment other than approved electrical equipment of a kind or type and rating approved for the specific purpose for which it is to b e employed.

2.1.11 Deviation or Postponement (1) 10 any case where deviation or postponement

of this Code may be necessary, special

permission shall be obtained befo~ 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, any electrical equipment under any of the following conditions: a) If the equipment is substandard with respect to the sample' on which approval was granted. b) If the conditions of use indicate that the equipment is not suitable. c) If the terms of the approval agreement are not being carried out.

2.1.13 Installation of Electrical Equipment (1) Electrical equipment shall be installed as to ensure that, after installation, ,there is ready access to nameplates and access to parts requiring maintenance.

2.1.14 Damage and Interference (1) No person shall interfere with any electrical installation or component thereof except when, in the course of alterations or repairs to non-electrical equipment or structures, it may be necessary to disconnect or move components of an electrical installations. (2) It shall be the responsibility of the persGiDiCarryingout thelalterations or repairs to ensure that the electrical installation is restored to a safe operating condition as soon as the progress of the alterations or repair will permit.

22

EBCS-1 0 1995



1.1 1.1.1

TECHNICAL Conventional Symbols

(1) Graphical symbols that are to be used in all drawings, wiring plans, etc for electrical installations of buildings shall be as indicated in Section 26 of this Code. 1.1.1

Coordination

(1) Proper coordination and collaboration between the 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 tile 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. 2.1.3

.Location and Requirement of Substation

(1) The ideal location of an electrical subsbttion 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 !>eabove the highest flood level ofthe locality. 'In this case, the load centre would be somewhere between the geometrical centre andthe 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

(I) In allocating area of a substation, it shall be noted that the flow of electric power is from su~ly 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


(2) The following rooms are required in a substation: a) Switchgear Room - Supply 60mpany'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.

d) 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 larg~ installations other than where a substation is provided, a separate switch room shall be provided; this s,hall 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 duct and horizontal ducts may also be required for running cable from the switch room to the foot of each rising main. Such cable ducts shall be reserved for .the electrical services only which may, however, include medium and low voltage installation,

such as call-bell system,s; telephone

installations should be suitably segregated. 2.2.5

Location

and Requirements

of Distribution

Boards

(1) The electrical control gear distribution boards and other apparatus, which are required on each floor may conveniently be mouuted 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

(1) Information regarding provjsion for and location ofPBXlPABX

shall be obtained from the

relevant authority and adequate space should be provided for installation of t!te boards.

24

EBCS-10 1995



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 conditionswhich may include some .or all of the following: a) Type of supply. b) Envisaged load having regard to the requirements of the owner or occupant. c) The probable modifications and future extensions. d) The degree of electrical and mechanical protection necessary. e) The probable operation and maintenance cost taking into account the electricity supply tariffs available. £)

The relative cost of various alternative methods.

g) The need for radio and telecommunication

interference abatement.

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

2§

ELECTRICAL

INSTALLATION

OF BUILDtNGS

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

(1) 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) f) g) h) i)

D k) 1) 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 REQUIREMENTS

(2) Each service box, at the time of installation, shall be marked in a conspicuous, legible, and pennanent 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 (1) Careful attention shall be paid to the m~chanical execution of the work in connection with any electrical installation. (2) Any insta1!ation that has been badly arranged or poorly executed, either generally or in any particular way, will not be accepted by the Authority having jurisdjction.

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 mechanicalor 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 canreasonably be expected to receive during its intended life. (2)Where an authority is to be responsible for the operation of the installation, that authority shallbe 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 out. b) The effectiveness ensured.

of the protective measures for safety during the intended life

IS

c) The reliability of equipment fot proper functioning of the installation is appropriate to the intended life.

2.4.6 Enclosures (1) Degree of protection provided by enclosures for ~lectrical equipment shall be in accordance with mc 529.

28

EBCS-10 1995


3

SECTION

LJ..JUMINA TION

3.1

SCOPE

(I) This Section of the Code gives guidance on design and installation of artificial lighting systemsin interio.rs; it also applies to artificial lighting of outdoor areas.

3.2


(l) The following references contain provisions which, through reference in this text, constitute provisionsof the Ethiopian Building Code Standards on Electrical Installation of Buildings. (a) BS 8206: 1985

Part 1 - Lighting for Building.

DIN 5035:1990

Part 1 - Artificial Lighting, Terminology and General Requirements.

(c) DIN 5035:1990

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

(d) DIN 5035:1988

Part ~ - Artificial Lighting of Interiors, Hospital Lighting.

(e) DIN 5035: 1983

Part 4- Artificial Lighting of Interiors, Special Recommendations for Lighting Educational establishments

(t) DIN 5035:1987

Part 5 - Artificial Lighting of Interiors, Emergency Lighting.

(g) DIN 5035: 1988

Part 7 - Artificial Lighting ofInteriors, Lighting of Rooms with VDU Workstation or VDU Assisted Workplaces.

(b)


EBCS-10 1995

29


3.3

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.

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 (E,)

the nominal value of the mean illuminance

that the lighting

installation is {fesigned to illuminate.

light loss factor (V)

the ratio of the rated illuminance,

En'

to the design value of the

mean illuminance of a lighting system.

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 uniformity

average

illuminance

with

a certain

degree

of

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-1 0 1995


SECTION 3: ILLUMINATION

. 1\

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

/\

1\/

-

1\

\/

.._---_

- :-;-.-.

\/

/\

\/

..---.-

1\

\ " I \

I \ I \

I

I \

I

I \ A

;. a) grouped

Figure 3.1 Generallighting

b)awitched

/

I/\ \

/\ 1\

V \

1\ 1\

/ V \

/\

/ \

Figure 3.3 Locallighting


B

Figure 3.2 Localized Lighting

EBCS-10 1995

31


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).

Note:

A distinction is made between:

disability glare, defmed as glare causing an actual physiological reduction in visual capability (impaired,

perception of contrasts and forms), and

discomfort glare, defined as glare considered solely in terms of its psychological effect on the occupant. Discomfort glare experienced by the occupant of a room increases with time and leads to premature fatigue and a reduction in performance, performance

direct glare

attitude, and well-being.

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 main disturbances caused by such reflection are contrast reduction, and impaired accommodation and fusion.

colour appearance

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

Note:

The colour of the light emitted by a near-white

sources can be indicated by its correlated colour

temperature (CCT). Each lamp type has a specific CCT; but for practical use, they have been grouped into three classes (see Table 3.1).

Table 3.1: Correlated colour temperature classes .

-

Correlated colour temperature Intermediate Warm (white) •(daylight WW (white) Cool whlte)-• NW TW CCT CI18S H

5300 3300

< CCT < 5300

32

EBCS·1 0 1995

ETHIOPIAN BUILDING CODe STANDARD


c%ur rendering

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 s~ace accurately can be conveniently quantified by' the CIE general colour rendering index. This index is based on the accuracy with which a set of test

Note:

colour'are reproduced by the lampt of interest relative to how they are reproduced by an appropriate standard light source, identical agreement being given a value of tOO.Ou. Each lamp type has a specific CIE general colour rendering index; but for practical use they can be divided into a number of groups (see Table 3.2)

'Table 3.2 Colour rendering groups Colour rendering groups 1A

CIE general colour rendering Index (AJ

R.>90

18

Typical application

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

3

40< R. < 60

Wherever moderate coiour rendering Is required. Wherever colour rendering is 01 little significance but marked distortion 01 colour is acceptable.

4

20 < R. < 40 Wherever colour rendering Is 01 no Importance at all and. marked distortion 01 colour is acceptable.

emergency lighting

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

safety lighting

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

t For tabular florescent lamps apparent colour and colour rendering characteristics, refer to Table 3.4.


EBCS-10 1995

33


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

escape lighting

sll/ety /igllting

Note:

lor partial/Ju

hazardous WOI'kplacu

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

Particular hazardous workplaces are those which represent an immediate risk of accident or a potential source of danger to third parties if the supply to the 'lighting should fail, raised platfonns, stages, race-courses

and arenas counting as particularly

theatre

hazardous workplaces.

standby lighting

an emergency lighting which can assume the function of normal artificial lighting for a limited period so as to enable normal activities to continue.

response time

the interval between a failure in the power supply to, the normal artificial lighting and the provision of the required illuminance by the emergency lighting.

.rated duration 01 operation

the period of time for which an emergency lighting system is designed to operate.

Umit duration 01 operatiOn

the minimum period of time during which an emergency lighting system shall still be capable of achieving the minimum illuminance specified for the given application.

Note:

This concept applies specifically to battery-operated

systems.

lI$efullife

the duration of an emergency lighting system from the date of its commissioning up to the point in time at which it only achieves the limit duration of operation.

safety luminaries

a luminary which mayor may not be provided witll its own power supply and which is used for safety lighting.

,34

EBCS-10 1995



escape sign luminaries

a moulded luminaire bearing a graphical symbol to serve as an escape sign; it indicates and assist the ide~tification of. escape route.

standby lighting luminaries

a luminary which mayor

may not be provided with its own

power supply and which is used for standby lighting.

3.4 3.4.1

LIGHTING REQUIREMENTS D1umin~nce

(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 install~ions are to be based. (2) For indoor workplaces that are manned full-time, a minimu~ rated illuminance of 200.01x shall be provided unless other factors (such as nature of operation, physiological reasons) require different values.

v

(3) (it) In interiors designed for permanent human occupation, a minimum rated illuminance of 100.01x 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 ofthe rated illuminance; at no single workplace shall illuminance ever fall to less than 0.6 times the rated illuminance.

3.4.2 Luminance (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, ------------dt?,sktops. .


EBCS-10 1995

35


3.4.3 Glare (1) Glare shall not be caused by lamps 0/ luminaries (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. \I (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,avoide,d. If the ratio Ez (cylindrical):En (horizontal) at a hight of I.20m above floor is not smaller than 0.3, unduly hard shadows can be avoid~d. (3) Deep shadows producing excessive. luminance contrasts shall be avoided.

3.4.5 Colour Rendering (1) For inspection and comparison of colours, the CIE general colour rendering index ~ shall not exceed 90 and the rated illuminance shall be IOOO.O/x. (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

Illuminance

(1) The minimum illuminance of the safety lighting for escape routes shall be 1.0/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 I5.0sec.

(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 l.Ohr) or % (for 3.0hr) of the 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 poil}ts where it is necessary to emphasize the positions of potential hazards.)

3.5.2 Safety Lighting for Particular Hazardous Workplaces 3.5.2.1

I/Iuminance

(I) The minimum illuminance for such workplaces shall be O.1En (rated illuminance specified for the task and room of such workplaces in Table 3.5) but not less than IS.O/x. (2) The minimum illuminance for platform and theatre stages shall be 3.0/x, and I5.0/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-1 0 1995

37


3.5.2.3

Response time

(1) 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 be met 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

REQUJ:.REMENTS FOR VARIOUS TYPES OF BUILDINGS

3.6.1 General (1) 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



3.6.2 Industrial Buildings (I) In addition to the lighting required for specific tasks, a general 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 IOOO.Olx

shall be provided.

3.6.3 Offices (I) As indicated on rated illuminance tables, for general offices illuminance of 500.01x and for drawing offices illuminance of 750.01x shall be provided. (2) Where VDU (Visual Display Units) are used, the illuminance shall be restricted to 500.01x 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 more than 3: 1 with a minimum illuminance for lUtycontinuously occupied area of 200.0/x. (4) Where locallightingjs used, the ratio of illuminance between task area and the surrounding area shall not exceed 3: 1. (5) 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 dinning rooms and restaurants an illuminance of 100.0lx is recommended on a dinning table. (2) In lounge and public bars, an average illuminance of 50.0/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 500.01x.


EBCS-10 1995

39


(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 (1) 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. (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 appJy 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.Ocdlm2while the luminance of the ceiling shall nowhere exceed 500.0cdlm2•

40

EBCS-10 1995

ETHIOPIAN B~ILDING CODE STANDARD


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 IOOO.Ocd/m2•

c) (i) For the examination and treatmen~ of patients at.the bedside, a rated horizontal illuminance of 300.Olx, inclusive of the general lighting, shall be provided O.ISm 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 (iii)

ISO.Olx.

The uniformity ratio of illuminance Emin:Eishall here not be less than 1:2.

d) (i) Night watch lighting with illuminance of approximately

S.Olx

shall be provided for

keeping patients under observation during the night. . (ii) In wards occupied by infants, a rated illuminance of (3) (a) General lighting with a rated illuminance of

500.0lx

20.0lx

is recommended.

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

IOOO.Olx

is generally

required at the site of examination. (4)

(a) The lighting in operating theatre shall always be designed in conjunction with the lighting of the operating theatre field. (b) In view of the illuminances of

20,OOOlx

to

IOO,OOO.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 I.Om above floor level.

IOOO.Olx

at a height of

(5) (a) Standby lighting system shall be provided for the 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 ensure continuous illumination. 800

900

Reading plane Examination plane

Plane'a;-'

be~ lurf.lce °l C> C>

0'

gl •....

::

lG

Figure 3.4 Reference plans of a hospital bed

3.7

OUTDOOR LIGHTING REQUIREMENTS

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


EBCS-10 1995

43

I1c

i;~' :

G

VI

r

.J:>. .J:>.

Table 3.3 Typical characteristics of lighting sources used for general lighting Hot cathode Characteristics

Tungsten

Tungsten

Low-pressure

Filament

halogen

sodium

High-pressure

tul;lular

sodium

Cold cathode

tubular

High-pressure mercury

Mercury

halide

fluorescent

fluorescent

fluorescent

40 to 60

35 to 55

65 to 85

20 W/mto 30

50 to 2000

250 to 10000

5000 to 10000

5000 to 10000

Range of luminous efficacy (1.0 Irn/W)

8 to 18

18

to 24

100 to 175

65 to 120

35 to 90

10 to 200

50 to 1000

4

Available wattage range 25 to 1500

rN>

100 to 2000

to

125

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

20000

3

2 or 4 depending

on

Can very widely depending used.

lamp pressure

on additives

Manufacturers

should be consulted.

No

No

Yes

Yes

Yes

Yes

Yes

Yes

Any

Horizontal

Horizontal

Any

Any

. Any

Any

Some restrictien

Run-up time (min)

Immediate

Immediate

6 to 12

4 to 7

Immediate

Immediate

4

5

Restrike time (min)

Immediate

Immediate

3

Immediate

Immediate

10

10

2700 to 6500

2700 to 6500

4000

3600 to 4400

Need for control gear

Operating

CCT(K)

Note:

position

25000 to 3000

28ooot03100

Not applicable

2200

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

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

s, which al sky light orange ower compact

Apparent colour Lamp name Typical application Intermediate 1A 1A Cool 18 18 23given 3oranges,· Warm Cool subdues yellows and deep reds Warm reds slightly subdued, blues subdued and shifted group Equal emphasis to emphasizes allmatching colours Colour rendering is needed Emphasizes Emphasizes yellows oranges, and, greens to less blues andextent. blue-violets, and green violets; similar Similar to to IInorth northsky light/colour light; towards blues emits and, violet yellows, and extent, greens; Ishops, to less extent, greens BS 95:Part 1fine is required Factories, offices and shops Commercial/public buildings subdues some yellows f'nd significant proportion of daylight is admitted Factories, Hotels, offices homes; and shops, as adeep replacement particularly where for a daylight I[but Social colour Used but fl
"

~

VI

"

•••

0\

Table 3.5 Indoor workspaces recommended

,

Colour kinds and search and 1.6 Building services installations 1.2.2spaces Warehouses with goods of different 1 rendering 1.3.1 Aisles gangways lA limitation 1 General 2A 6 glare 2 50 500 20 33121when 2A 200 200 100 4ww,nw 3 5 Remark 300 50 2 Class of ww,nw ww,nw Supplementary mirror atmosphere. lighting to optional create a and specific be used lighting is Incandescent lamps direct Warehouses withmay reading tasks I1.2.3 Control group 1.3.2 platform 100 ww,nw En. in Ix I retrieval 1.2.1 tasksWarehouses for goods of one kind or of large unit size 1.1 Circulation zones in storerooms

L

-

I

appearance

illuminance

group used. 50 are luminous anels

" •••

--

Table 3.5 Indoor workspaces recommended illuminance (conte'd)

1 4Colour 33En2 6areas. ! Only rendering IAdjustment 3ww,nw 32 Class of direct circulation 35 Remark illuminance to 2 Colour glare luminaries ww,nw For persons of rated Only adjoining spaces; En2 =luminaries En of adjoining En1~0.1 ww,nw the shed entrance is entrance isshed to beof 'limitation interior. area of the The interior The interior area 3 adjoining tEn of the adjoining 3 illuminated 0,2spaces Ent I

100 luminous 2 100 0,5 x Ent Ent to without be illuminated. En. In!!

ww,nw

where En1 = En of the I

~

00

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

3

2 Rated illuminance

Type of interior and/or task

--

4 Colour!

Colour En

appearance

in~

I

1_

group_

I

6

----1 .

--

I

rendenn .

5

9

'I

... Class limitation of direct glare

I

__

Remark

I

I

I

3 Offices and similar rooms

I

I

I

I I

I

3.1 Offices with daylight-oriented

workplaces,

all in immediate vicinity of windows

300

ww,nw

2

I

1

I Workplace-oriented

general lighting;

minimum of 0.8 En at workplace

500

ww,nw

2A

High reflectance: ceiling: 0.7 minimum, walls/partitions: 0.5

1000

ww,n',

2

minimum,

750

ww,nw

2A

permitted

300

ww,nw

2A

100

ww,nw

2,

3.7 Rooms open to the public

200

V'IW,nw

2A

En referred to working

3.8

500

ww,nw

2A

drawing board of 75° to the

3.2 Offices 3.3 Open-plan offices

with average

reflectance with high reflectance 3.4 Technical drawing office

3.5 Conference and consultation 3.6 Reception rooms

Data processing

rooms

~

rooms

local workplace

lighting

plane of

horizontal at the centre point of the board and a height of 1.2m.

Table 3.5 Indoor workspaces recommended illuminance (conte'd) 1 rendering group 21, lA 33 appearance limitation nw 12A 3required 45 3Colour 32 ww,nw,tw ww,nw 6300.02s. ww,nw ww,nw ww,nw 2recommended 200 i I Icontrolled Remote process engineering plants 50 750 1000 Colour 500 300 100 500 lighting recommended, workplace 300 Class of than direct glare Where for operational reasons, En be less En> I -may against light sources of I Local Remark with shielding 2A I illuminance, , observations posts engineering plants otherparts; light glazing; types. materialsmixers, glass at grinning blowing plantquality in brickworks griding and engraving; medium tasks 4.1 Workplaces or zones at furnaces/kilns, at raw 5.1

-

~ \0

ov.

Table 3.5 Indoor workspaces recommended illuminance appearance

1 3group 345 32112A 6 2 2A Cliiss of direct glare wvr,nw ww,nw limitation ww,nw,tw ww,nw Colour rendering g, may exceed 5oo.01x Where required for operational

Colour Vfoundrl&! than 0.1 mm stations intervention machining plant plants permissible deviations greater cold rolled less sectional strip mills,deviations

than 0.1 mm 6.1 plants ofnotsmall requiring 7.1 Production Hammer-forging parts manual

reasons,

~

100 50 500 200 200 300 500 750 300 200 illuminance,

En'

~ may be lessRemark than 3oo.0~

(conte'd)

Table 3.5 Indoor works paces recommended illuminance (conte'd) Remark appearance 1 3Colour 6 2precision 50 1000 lIIumlnance,E., 3 100 300 200 200 2 300 500 1132manufacture; 3Alimitation 750 45 Underfloor men-sized trenches, belt ww,nw ww,nw ww,nw ww,nw,tw ww,nw,tw Class of direct glare 2Tool, Local gauge workplace jig lighting recommended Colour rendering group 7.14.1 7.16.1 Electroplating 7.12.1 Low precision mechanics; highprecision assembly conveyor roads, cellars, etc. 7.12 Assembly

Vl

N

Table 3.5 Indoor workspaces recommended illuminance (conte'd)

9.1

Colour assembly lines with local workplace 2B 3operational 13lighting limitation 3required 45 6 2glare 3 21-212A ww,nw ww,nw ww,nw,tw ww,nw,tw Where fordirect operational require. Cable manufacture; varnishing and impregnation By providing supplementary lighting Loading plant with ifww,nw the conditions so Shielding against at fluorescent may be dispensed rendering Electrical engineering Industry group Class Colour of direct glare while work is carried out. stations rooms 7.18.1 Shell manufacture and armatures wire of coils; simple assembly tasks;300.0~. winding of coils reasons, ~ maywith be heavy-gauge less than 8.1 7.18 Motor vehicle manufacture

50 300 50 .500 200 100 500 1000 750 300 Remark illuminance,

group 13 Industry 1A 3 43 3 2 making limitation 521121A 2A 1B 500 nw,tw 12A 6 clock ww,nw,tw ww,nw ww,nw ww,nw,tw Jewellery Electrical engineering Industry, watch and (conte'd) Work recommended at woodworking machines; turning, Local workplace lighting Woodworking Colour appearance Class of direct glare Colour rendering 11.6 calibration chamfering, marquetry components work Industry gauge winding wire ofdressing, coils andrebating, armaturesslotting, with mediumcutting, sawing,sinking Manufacture of jewellery 11.1 10.1 Steam pits

1500 1000 500 100 Remark 200 500 1500 300 750 1000 illuminance,

,ac:l;';'::.~3nded Local workplace

lighting

(

Table 3.5 Indoor workspa~es recommended illuminance (conte'd)

--- ww,nw Colour --Remark appearance -500 3glare 1-----------2A limitation 2000 1000 750 300 1A 200 2A Cia ••321of of 300 45 6sewing dlutet incidence. ww,nw,tw 1500 ww,nw I Industry ww,nw,tw", illuminance, For tubs, due edtention be render!ng given Leather selection correct lightmust incidence; for -- -500 Saddlery work; quilting; polishing; group --recommended. 2 Colour ...............

___

1

-

•• OOO+OI}o(. WW.OW

~I-

13.1 12.1 WorkWork ed vl'.ds; tubs, pits ed Hollanders,

edge

1-

lC)CaJ _ClIrk,?,I~~ -

3 For dark materials, increase to shoe manufacture mills cardboard fabricedion Local lighting to avoided vertical by lighting, means reflections ofworkplace suitable being light hand composing, obliquely the AV6idance of reflected glare by sorting; pressing; cutting to from size punching; composing; make-ready

runners, grinding

,lighting

side.

Table 3.5 Indoor workspaces recommended illuminance (conte'd) 2 Type of Interior

and/or

rated illuminance,

task

Em

-t--~-

Colour

Class of direct

appearance

.rendering

glare limitation

Colour

InJ!

group 13

Leather

Industry

5

4

6

Remark

(conte'd)

13.4 Leather dyeing (mechanical)

750

WW,nw,tw

2A

For surface inspection tasks, provide supplementary

13.5 Quality control 13.5.1 Medium standard 13.5.2 High standard

750. 1000

nw,tw

13.5.3 Very high standard

1500

nw,tw

18 18 18

100

tw,nw

1A

13.6 Colour matching

nw

1,

lighting with oblique

incidence. Local workplace recommended.

lighting

1 1

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

14 Manufacture 14.1

and processing

Workplaces

and work zones at baths and in

bate breaking 14.2

Combing,

areas

jute and

Warping, beaming,

14.7 Trimming;

perching;

hemp spinning

spinning,

winding, twisting, braiding, weaving Comb pricking; 14.6 Millinery

300

ww,nw

3

300

2

ww,nw

2A

2

500

ww,nw

2A

750

ww,nw

2A

spoiling and

knitting, and

sewing; block printing

burling

14.8 Goods inspection; 14.9 Invisible mending

colour matching

750

ww,nw,tw

2A

1000

WW,nw,tw

2A

1000

ww,nw,tw

1A

1500

2A

I VI VI

3

drawing, teasing, sizing, card

cutting; slubbing; 14.3 Dyeing

H.5

3

ww,nw 200

washing, ironing, devilling and

carding work;

14.4

of textiles

nw,tw

1

Local workplace recommended.

lighting

For colour matchIng tasks, shield from light sources with a different illuminant.

--

Table 3.5 Indoor works paces recommended iIIuminance(conte'd) Colour rendering' 1glass 2A 2A limitation ww,nw nw 300 2in 200 2 11 1A 500 45 3 6 ww,nw ww,nw,tw Cutting sorting of Workplaces Making For colour of delicatessen matching, and work zones shield products; from abattoirs, Colour Depending matching; on the laboratories layout ofin the Workplace and zones breweries Inspection of jars andand product Sorting and washing offruit produce; Class ofwork direct glare group 1000 Remark Colour appearance recommended. beds cellar sorting kitchens; cigar and cigarette manufacture light sources with a different control; garnishing, decorating, and and barrels, fermenting cleaning, leaf sieving, tobacco; peeling, fermenting grinding, mixing. packaging i1luminant. vegetables Local workplace lighting workplace, ensurE! adequate vertical cooking work malthouses; zones and inboiling sugar washing, in refineries. canning tiling for and in drying chocolate factories; workplaces and 15.1 16.1 Sales areas

Rated illuminance, 500 300

illuminance.

Table 3.5 Indoor works paces recommended illuminance (conte'd) Remark 13 1B 1B 2A ww,nw ww 1A direct Colour 45 2 rendering 2-1 Colour 1 Hotels and restaurants 6 steel components 213 Class of ww,nw,tw ww,nw ww,nw Removing rust and painting glare limitation Injection Local workplace lighting permitted I moulding 19.1 18.1 .118.2.1 Reception Washing system branches) 17.1 18.1

Rated illuminance, 200 300 500 200 750 200 300 1000 500 group 500

ww,nw

Table 3.6 Outdoor workspaces .Colour rendering group

0.2 0.4 3 92 0.2 4 0.5 3relate 40.34 5= centre 4of related Sw s. •.Uniformity s. and illuminance, •.... and g2 tog,the to the2 centreline line of the gi~O.08 shall gi~ s..inl£ be 1.0~minimum. Remarks

1 of thepath uminance, En path. -.. cross traffic and a speed limit of 50.0km/h 30.0km/h or heavy 2 Parking areas 1.3.2 3.1 Works roads with loadingareas andareas unloading zone areas or with transshipment 1.1 Container Gates 3.1.1 Open storage and circulation

10 20

Rated 50 20 Sn~ 3 5 in

!!

ance,

Table 3.6 Outdoor works paces (conte' d) I

Colour group , 44 I 4 1 rendering ,I 0.2 30.2 2 I••• I lighting 0.5 Wharfs Docks 20 mixed traffic 0.2 0.2 5to 0.2 II3shipping Idepot I for passenger traffic Repair facilities in harbour Workspaces inilluminance, areas Uniformity oflocal iI Supplementary Quayage Dazzling ofIE. workplace be avoided. 10 9! =E~ I Remarks 30 34!I !I I 3.3.1 Unit loads I I I 3.1.2 Loading and unloading containers I

II i IiI

Rated 35 30 30 100 20. 20 50 10 g." in Ix

I required in containers.

0\

o

ance,

Table 3.6 Outdoor workspaces (conte' d)

EN

- 43 group Colour rendering 1 5 Paths and roads 2 0.5 0.2 Circulation areas 0.2 3-0.5 44 where Directional Lighting lighting only needed Uniformity of Switchboard plant Illuminance, 91 0.2 = Em~ Remarks 9.1.1 Conventional fuel power stations 10.1 9.1 11.1

Rated 30 5 3 2020 20 10 100 20 10 in Ix

,

Table 3.7 Colour appearance 1 supplementary ) 43direct stacks cabinets 23exhibited, 51-23aids 6 2 and ww:nw restriction Remarks ww,nw ww,nw wW,nw ww,nw Room for objects teaching and of collections glare Community If necessary, rooms platforms lighting lighting shelves. for for Quality rendering Colourclass property group 3.6 above

3.1 1.1 Corridors 2.1 Roofed recreation area

Guideline values for educational establishment lighting

200 10<:\ 50 200 300 100 20

200 300 500 illuminance,

~

Table 3.7 Guideline values for educational establishment lighting illuminance,

En

3property 5 I Remarks rendering restriction Colour Quality class direct glareof appearance Colour

Ix 2 4 in Rated

(conte'd)

6

group

Type of space or activity

The main chalkboard and/or demonstration desk require supplementary lighting.

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

300 300'

ww,nw ww,nw

2 2

50ci

ww,nw

2

ww,nw ww,nw

2 2

I

4.4 Open-plan teaching spaces - with high reflectance' - with medium reflectance

750 1000

II 5 Teaching rooms for special purposes I

5.1 5.2 5.3 5.4 5.5 5.6 5.7

6.1 Lecture theatres with windows 6.2 Lecture theatres without windows

t The

500

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

6 Lecture theatres

1) At the working positions, a minimum of O.BS is required. 2) The TIluminancerequired 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.

500 500 500 500 500

!

I I

I

_,nw ww,nw ww,nw ww,nw ww,nw ww,nw

I I I I I

2 2 2 1

I

2 2

ww,nw

- --1-I

~._~

---l-

700

500 750

I

I I

values of the luminance restriction curve belonging to the next highest nominal illuminance

l--

1t

l

I

2

i

I

2

I

I

1

I

I

I

1 1

II

I

J.----.--+----1

I

I

ww,nw ww,nw

1t

: I

2 I

shall be observed

2

I

-

4) En positioned with respect as forofuse the at drawing-board 75° from the horizontal, the centre of the board being

---

7at a height of 1.2m

ry yonitor metry ycopy

Table 3. 8 Guidance value for hospital lighting

T

Room type

I

I

of

"IYIpelof alct vlty

type

I um nat on

Bedded area

--

Infants ward

Night-watch General examination

and

rooms

Special examination treatment rooms

General lighting At site of examination

examination

hting

For ophthalmic

'I

L I

examination

91t ng

:

ww ww

I I

200

I :

500

I

>1000

L--

renderinggro up

--,

300

I

ww

I

:

20

I

I~ I Ii

I

20 500 55 50

i i

1

I

1 1

Quality class for restriction 9 areof direct I

i I

1 1

ww

!

1

r---

ww

I'

1

II

1

I

'I

. ww,nw

•••

ww,nw,

I

1 1

I I

I---~---I I I

I I

,

1 1

I ,

•

I

1

!

1

I

I

I I

I

I I

I I

co our

I

'II

colour

I

200

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

U hI

-r~-ww

and Preparation

For endoscope

lighting

='

illuminance, n~ E I •.•.

I

Night lighting General lighting

I I

-i--~- t I

...

I General lighting I Reading lighting Night watch lighting Examination lighting

treatment

Ratad

I

i

1 1 1 1 1

-----:

L

I Remarks

!

Reduced

glare for patients

I I

Approximately

5.0~

I

General lighting at workp,laces not less than 160.0Ix +-~~--~~-=----------I , I I

----~

--+ I i I

If required, switchable controllable illuminance

or

to give lower values

1

1 1 1

If required, switchable

1

controllable illuminance

1 1

for radiographic

examination

or

to give lower values

Table 3.8 colour Rated colour nw - lighting 1ww 11 Remarks 500 1WW nw 300 Illuminance: from 20000 to1000 100 tw 100000.0Ix, ww,nw 1ooo.01x restriction of for direct minimum; desired ww,nw General lightinglighting for changing rendering room Workplace Reduced required. glare lighting, patients if General Quality class for glare Type of in activity / Type of Ughting group1) Wash rooms treatment rooms areas Medicinal rooms baths (conte,d) preparation treatment Intensive care areas Operating Dialysis theatre suites for dermatological examinations for dentalrooms examinations

s.. !!

Guidance value for hospital lighting (conte'd) Illuminance,

illuminance:

2OOO.01x

Table 3. 8 Guidance value for hospital lighting (conte'd) Rated Colour colour -1 Remarks 1 2 2 1nw 2-1 Bedded areas ww ww nw nw nw restriction of direct 200 50 300 500 100 1000 300 200 100 for >5000 ww,nw If required, workplace Lighting difficult visualof tasks General Sanitary lighting blocks connecting to Quality for lighting forclass filling hypodermic rendering glare Type / Type ~~---- of activity group' in...!! Lighting etc. - day-time syringes, sorting medicines I

illuminance

s..

-

ELECTICAL INSTALLATION OF BUILDINGS

SECTION

4

CONDUCTORS

4.1

SCOPE

1) This Section of the Code specifies the nom inal cross-sectional areas of conductors in electric cables and cords used for lighting, appliance and power supply circuits for a nominal voltage not exceeding 1.0kV. 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

4.2

purposes.


(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) BS 767]:]992

Requirements

for

Electrical

Installation,

lEE

Wiring

Regulations Sixteenth Edition.

66

(b) BS 6360:]991

Specification for Conductors in Isolated Cables and Cords.

(c) IEC 228:1976

Conductors of Insulated Cables.

(d) IEC 50(46]):]984

International Electrotechnical Vocabulary.

(e) IEC 364-5-523:1993

Electrica] Installation of Buildings.

EBCS-1 0 1995

ETHIOPIAN BILDING CODE STANDARD

SECTION 4: CONDUCTORS

(1) C22.1: 1990

4.3

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

DEFINITIONS

\

j

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

ETHIOPIAN' BUILDING CODE STANDARD

EBCS-1 0 1995

67


mineral insulation

insulation consisting of compressed mineral powder.

conductor screen

an electrical

screen of non-metallic

and/or metallic

material

covering ~ne 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 conductors may also serve as shields).

core (insulated conductor)

an assembly comprising a conductor with its own insulation (and screen if any).

sheath (jacket)

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

oversheath

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.

single-conductor

cable; slng/e-cote cable

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-1 0 1995



cord

a flexible cable with a limited number of conductors of ~mall crosssectional area.

aerial (insulated) cable

an insulated cable designed to be suspended overhead and outdoors.

heating cable

a cable with or without a shield or a metallic sheath, intended to give off heat for heating purposes.

4.4

SIZE OF CONDUCTORS

4.4.1

Phase Conductors in a.c. Circuits and Live Conductors in de circuits

(1) The minimum nominal cross-sectional area of conductor shall be: a) .1.0mm2 for cables and insulated copper conductors for power and lighting circuits; b) 10.0mm2 for bare copper conductors for power circuits; c) 16.0mm2 fo~ bare aluminium conductors for power circuits; .•. d) O.5mm2 for flexible cables of copper conductors for extra low voltage.

4.4.2

Neutral Conducton

~

,. l

(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 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 .less than that of the· phase conductor(s).


EBCS-10 1995

69


4.5

AMP ACITY 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 in the appropriate table of currentcarrying capacity in Annex B of this 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 to a bare conductor busbar, its type of insulation and/or sheath shall be suitable for the maximum operating temperature of the 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, load current.

4.6 FLEXIBLE CORDS (1) Flexible cords may be used for: a) electrical equipment for household or similar use having a rating of 16~OAor less at voltages not exceeding 230.0V and which is intended to be moved from place t-o place~. b) electrical equipment for industrial use which must be capable of being moved from place to place for operation; c) pendants; d) the connection of stationary equipment to facilitate its fnterchange; 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



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

pennanently 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 11.Okg. (3) Flexible cord shall be protected by insulating bushing or in some other acceptable manner where it enters or 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

OLO

OF CONDUCTORS

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

4.8

V'

MAXIMUM PERMISSIBLE 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 pennissible 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

Phase Phase Function Blue of core Brown Phase Brown Brown or black .Green-and-yellow Colour(s) of ' core Green-and-yellow Green-and-yellow

Protective Neutral Neutral

Table 4.2

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

Function

I Colour identification

Protective (including earthing) conductor

Green and yellow

Phase of a.c. single - phase circuit

red or yellow or blue black red

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

yellow blue

Phase B of 3-phase a.c. circuit Positive of d.c. 2-wire circuit

red

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

black red red black blue

Negative of 3-wire d.c. circuit

72

EBCS-1 0 1995

ETHIOPIAN SILOING CODE STANDARD


Table 4.3 Maximum conductor operating temperature Conduct

60°C rubber Insulation material 220 200 250 160(general 250°C Mineral 160 160/140t temperature 85°C 160/140t p.v.c 70°C p.v.c purpose) Umltlng final combustible touchnor contact with - Plasticinmaterials covered or exposed to

80 70 60 90 105 (sheath) 85 Conductor 70 (sheath) operating temperature

°C

70°C p.v.c (general purpose)

t

above 300.6m2


EBCS-1 0 1995

73

ANNEX

PREFACE TO THE TABLES IN ANNEX At AND ANNEX Btt FO,R CABLES AND FLEXIBLE CORDS A.I

BASIS OF TABULATED CURRENT -CARRYING CAPACITY

The current-carrying capacity set out in Annex B takes account of IEC Publica~ion 364-5-523(1983), so far as the later is applicable. For types of cable not treated in the IEC publication (e.g. annoured 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

Annex A: Correction factors

tt

Annex B: Current-carrying capacity and voltage drop

ttt

ERA Technologies Ltd, Cleave Road, Leatherhead, Surrey KT22 7SA

74

EBCS-10 1995



The tabulated current-carrying

capacity relates to a single circuit in the instanation methods

shown in Annex A of Section 8, in an ambient air temperature of 30°C. The curr
CORRECTION

The current-carrying

FACTORS

FOR CURRENT-CARRYING

CAPACITY

capacity of a cable for continuous service is affected by grouping" by

ambient temperature,

by partial or total enclosure in thennal

insulating and for a.c., by

frequency. Annex A provides relevant correction factors as in the following:

A.2.1 Grouping

-..I

Tables A.I, A.2 and A.3 give the correction factors to be applied to tPe tabulated currentcarrying capacity where cables or
A-2.2 Ambient temperature

v

Tables A.4 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
In practice, the ambient air temperatures may be detennined by thennometers placed in free air as close as practicable to the position at which the cables are installed or are to be installed, subject to the provision that the measurements are not to be influenced by the heat arising from the cables; thus, if the measurements are made while the cables are loaded, the thennometers should be placed about 0.5m or ten times the overall diameter of the cable, which ever is the lesser, from the cables, in the horizontal phme, or 150.0mm below the lowest of the cables. Tables AA and A.5 do not take account of temperature increase, if any, due to solar or other infra-red radiations; where cables are subject to such radiation, the current-carrying, capacity may need to be specially calculated.


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 exceediQg 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, Irrespective

l!S

applicable.

of the type of overcurrent

protective device associated with the conductors

concerned, the ambient temperature correction factors to be used when calculating currentcarrying capacity (as opposed to those used when selecting cable sizes) are those given in Table A.4.

A.4

RELATIONSHIP OF CURRENT-CARRYING CIRCUIT PARAMETERS

CAPACITY

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

v

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

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. , ~

76

Ib

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

EBCS-10 1995


SECTION 4: -CONDUCTORS

In

the nominal current or current setting of the device. protecting the circuit against overcurrent.

12

the operating current (Le. the fusing current or tripping current for the conventional operating time) of the device protecting the circuit against overload.

G -

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

c.

for ambient temperature

Cj

for grouping for thermal insulation

Ct

for operating temperature of conductor.

Cg

In all circumstances, Iz must be not less than Ib, and In also must be not less than lb. Where the overcurrent

device is intended to afford protection against overload,

12

must not

exceed 1.451. and In must not exceed Iz (see A.5 below). Where the overcurrent device is intended to afford short circuit protection only, greater than Iz and

A.5

12

In can be

can be greater than 1.451z.

OVERLOAD PROTECTION

Where overload protection is required, the type of protection provided does n9t affect the current-carrying capacity of a cable for continuous service (lz), but it may affect the choice of conductor size.

The operating conditiQns 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 Iz 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

/"


Iz in turn to be not less than the selected value of

Iu,

the choice of conductor cross-sectional area

may be dictated by the overload conditions and the current-carrying conductors will not always be fully used.

capacity (IJ 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 the conductor to be protected.

-4

required of

In this case also, the choice of conductor size is dictated by the

overload conditions and the current-carrying capacity (IJ of the conductors cannot be fully used.

A.6

DETERMINATION OF THE SIZE OF CABLE TO BE USED

Having established the design current (Ib) 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 necessary from consideration of the conditions of normal load and overload is then detennined.

All correction factors affecting Iz (that is, the factors for ambient

temperature, grouping and thermal insulation) can, if desired, be applied to the values of multipliers.

-4

as

This involves a process of trial and error until a cross-sectional area is reached

which ensures that Iz is not less than Ib and not less than Iu of any protective device that is intended to select. In any event, if a correction factot for protection by a semi-enclosed fuse is necessary, this has to be applied to Iu as a divisor. It is, therefore, more convenient to apply all the correction factors to In as divisors. This methojl is u"sed in A.6.1 through A.6.3 and produces a value 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. noted that the value of

78 ~EBCS-10 1995

-4

It should be

appearing against the chosen cross-sectional area is not Iz. It is not

ETHIOPIAN BUILDING CODE STANDARD,


necessary to know Iz where the size of conductor is chosen by this method; but if it is desired to identify Iz the value is determined by the method indicated in A.3 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.6.1' Overload protection afforded by a fuse or a miniature circuits breaker (1) For single circuits -

divide nominal current of the protective device (In) by any applicable correction factor for ambient temperature (CJ given in Table

-

AA.

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 give in Equation

capacity (~)

(AI) below is not less than the value of nominal current of the protective

device adjusted as above:

~

~J!

-I)

Ca~:

(AI)

(Ampere)

(3) For groups -

divide the nominal current of the protective device (In) by the correction factor for grouping

(Cg)

given in Table::. A.l, A.2" or A.3:

(A2)

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-10 1995

79


(A.3)

and

(AA)

I: +0.48/;

(Ampere ).

[1~/e2l

t'c;; Ct."

The

size of cable to be used shall be such that its tabulated single-circuit current-ca.rrYing

capacity (It) is not less than the value of It calculated in accordance with Equation (A.2) ab~ve or, where Equations.(A.3) and (A.4) are used, not less than the larger of the resulting two values

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

A.6.2

Protection· device a semi-enclosed fuse

(1) For single circuits -

divided the nominal current of the fuse (In) by any applicable correction .factor for ambient temperature (CJ given in Table A.Sj

-

then further divide by any applicable correction factor for thermal insulation, (Cj); then further divide by 0.725.

J ~

The size of cable to be used shall be such that its tabulated current-carrying capacity (~) is not less than the value of nominal current of the fuse adjusted as above:

(A. 5)

80

EBCS-10 1995 /'



(2) For groups -

divided the nominal current of the fuse In by 0.725 and by the applicaole correction factor for grouping

(Cg)

given in Tables

AI, A2 ,or AJ (A6)

Alternatively, it may be selected by the following formulae, provided that the circuits of the group are not liable to simultaneous overload.

(A7)

and

(AS) (Ampere)

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 It calculated in accordanc€; with Equation (A6) above or, where Equation (A7) and (AS) are used, not less than the larger of the resulting two values of It.

(J)

Where correction factors C. and/or Cj are applicable, they are to be applied as divisors to -the value of It determined by the above Equation.

A.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 (It)given by

EBCS-10 1995

81


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

(Ainpere)

A.6.4 Variation of installation conditions along a cable route The procedures in A.6.1 through A.6.3 above are based on the assumption that all the 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 roost onerous conditions encountered along the route may be applied to the whole of the route. It is permissible temperature

to obtain more precise factors by calculation

of the various conductor

rises that will occur along such a route, provided that the appropriate

limiting

temperature of the conductor is nowhere exceeded.

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.Om 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 nolffial 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 (Ib) in amperes.

For three-phase

circuits, the tabulated mV/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/Alm)r values only are tabulated.

For cables having conductors greater than

16.0mm2 cross-sectional area, the impedance values are given as (mV/Alm)z, together with the resistive component (mV/Alm)r and the reactive component (mV/Alm)x The direct use of the tabulated (mV/Alm)r or (mV/Alm)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/Aim had been based. As regards power factor in a.c. circuits, the use of the tabulated mV/Aim values, (for the larger cable sizes, the tabulated (mV/Alm)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/Aim or (mV/Alm)z values leads to a calculated value of voltage drop higher than the actual yalue. In some cases, it may be advantageous to take account of the load power factor wher 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 16.0mm2

or less, the design value of

mV/Aim is obtained by multiplying the tabulated value by a factor

230

c= t

+ t p

given by

Ct,

12

i

(CC - ~)(t a

230

g

t

- 30)

(A. 10)

p

+ tp

where ~ is the maximum permitted normal operating temperature, DC. Equation (A. 10) applies only where the overcurrent protective device is other than a fuse and where the actual ambient temperature is equal to or greater than 30°C.


EBCS-10 1995

83


Note:

For convenience, the above fonnula is based on the resistance-temperature °C for both copper and aluminium

coefficient of 0.004 per °C at 20

conductors.

For cables having conductors of cross-sectional area greater than 16.0mm2, only the resistive component of the voltage drop is affected by the temperature and the factor Ct, is therefore applied only to the tabulated value of (mV/Alm), and the design value of (mV/Alm)z is given by the vector sum of

Ct

(mV/Alm), and (mV/Alm)x'

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 16.0mm2 or less, the design value of mV/Aim is obtained approximately by multiplying the tabulated value by the power factor of the load, CDS ~. For cables having conductors of cross-sectional area greater than 16.0mm2 the design value of mV/Aim is given approximately by:

CDS ~

[tabulated (mV/Aim),]

+ sin ~ [(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 240.0mm2 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: Ct

ii)For

CDS ~

cables having conductors of cross-sectional area greater than 16.0mm2: CtCDS

84

(tabulated mV/Alm)

~

(tabulated mV/Alm),)

EBCS-10 1995

+ sin ~ (tabulated mV/Alm)x)'


ANNEX

A

(NORMATIVE)

CORRECTION FACTORS Table A.I: Correction factors for groups of more than one circuit of single-core cables, or more than one multi~ore cable

,

([0 be -- -,-,--,, -, ,-0.69 0.70 0.71 0.73 0.39 0.90 710 3 20 14 90.38 16 0.6 0.66 0.77 0.76 0.62 0.81 0.90 0.90 0.50 60.67 0.52 0.54 0.57 0.60 0.65 0.43 0.72 0.75 0.79 5 4 12 0.41 0.45 0.46

applied to the corresponding current-carrying capacity for a single circuit in Tables B.I through B.8, B.9 through B.16, B.l7 throughB.l9, B.20, B.2?, B.28, B.31 through B.38, B.39 through B.46t)

7~.

0.90 0.65 0.77 0.66 0.72 0,74 0.70 0.71 I0.91 0.73 0.7 0.94

11) horizontal (method 11) cables Number touching of circuits (Method or multicore

../'

-

Vertical Spacedtt# Spacedtt

0.60 0.66

Correction factor (C~

;/.1

Il.-

l;", J.-'t

J.:r J,b 'c9-
3cs

t

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 (D.) where the horizontal clearances between adjacent cable exceeds 2D., no correction factor need be applied. Not applicable to mineral insulated cables, see Table A.2.

#

00 V\

/


U'f~(~~!St

Table A.2 Correction factors for mineral insulated cables installed on perforated tray (To be Applied to the Corresponding Current-Carrying Capacity for Single Circuits for Reference Method 11 ~ Table B.27)

Tray

.

l

1 -6Number 93 0.90 .0.95 4 0.75 0.80 0.70 0.75 1.0 1.0 0.85 21;0 of multicore cables er or1 of circuits 1.0 Multiconductor cables touching spacedt Arrangement of cables cables spaced 1trefoil t Single conductor cablestouching

Numb

Trays

Vertical

••

I

c

~I "C

, I

c

(

C

c

.! "C

~ C ~I

.!

l l

~ t

tt

Spaced by a clearance by between adjacent surfaces of at least one cable diameter (Dc) Spaced by a clearance between adjacent surfaces of at least one cable diameter ( 2De).

I

~

I

c

1 ~

Notes to Tables A.I and A.2

I 1

c

(i)

The factors in the Tables are applicable to groups of cables all of one size. The value of current derived from application of the appropriate factors is the maximum current to be carried by any {)f the cables in the group.

I

(

I;,

(ii)

If, due to known operating conditions, a cable is expected to carry not more than 30% of its grouped rating, it may be ignored for the purpose of obtaining the rating factor of its grouped rating, it may be ignored for the purpose of obtaining the rating factor for the rest of the group. For example, a group ofN loaded cables would normally require a group reduction factor of Cgapplied to the tabulated~. H,owever,if M cables in the group carry loads which are not greater than O.3CgLtamperes the other cables can be sized by using the group rating factor corresponding to (N-M) cables.

(iii) When cables having differing conductor operatihrgtemperatures are grouped together, the current rating shall be based on the lowest operating temperature of any cable in the group. (iv) Where the horizontal clearances between adjacent cables exceeds 2Dc, no correction factor need be applied.

86

EBCS-10 1995

ETHIOPIAN BUILDING CODE STANDARD ~

Table A.3 - Correction factors Cor cables installed in enclosed 1:renches ~taIlation

Methods 18, 19 and 20 of Annex A, Section 8yt

j' l' e-vCf

~[qq7

The correction factms tabu1atedbelow relate to the di'l""ition of cable illustrated m lrem No. 18 to lrem No. 20 of Annex A, Soroon 8, and are "1'Plicable to the curren~~. capacities for Reference Methods

1

0.93 0.92 0.88 0.90 0.89 0.87 10 0.81 2 0.76 0.87 0.71 0.82 0.75 0.85 0.84 0.79 3 8 0.67 0.73 0.81 0.66 0.72 0.63 11 0.90 0.61 0.56 0.88 0.83 0.64 0.89 7 0.57 0.52 0.60 0.68 0.51 0.69 0.74 0.63 0.48 0.53 0.67 0.80 0.66 0.72 0.78 0.59 0.82 0.73 5 0.50 0.41 0.43 16 two-core 0.83 0.85 0.59 0.74 0.80 0.65 0.49 0.55 ~0.65 0.91 0.86 0.82 0.80 0.78 0.77 0.69 0.78 0.49 0.86 0.54 0.62 4 6 0.46 0.76 9 0.44 0.47 threefouror two-core cables core four0.84 0.77 0.70 0.58 core threecore core threecables core or3 threefour-core two-core cables cables 63or or cables threethreecables or or fourfourfour\9.86 cables, 8 two-core or 2 single-core 0.56 cables, core cables, cables, core cables, cables, cables, or or 212 4 6or cables, cables, 9or cables, cables, 8 41 4or 12 twotwo24 12 single4 3 80.81 single-core 18 6 single-core singlecore'

12 or 13 of Annex A, Section 8, as given in the relevant tables of this Annex.

Installation Installatior:l Method Installation 18Method 6 single-Method cables 20core 19 12 single-core

cross-

~

{ 0)

~ ~

'0

o ~J

t (Y:)

-J

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.

.

00 00

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.

--------- 0.41 0.29 0.96 0.50 0.76 0.65 0.54 0.3 0.40 0.60 0.75 0.80 0.92 0.30 0.43 0.74 0.60 0.58 0.90 0.52 1.0insulation 80 95 85 35 60 55 0.95 0.94 0.32 0.93 0.79 0.87 0.35 0.55 0.77 0.67 0.89 '0.50 0.35 0.97 0.91 0.94 0.71 0.47 0.70 0.88 90 0.91 75 0.85 0.41 0.82 45 40 65 50 70 30 0.61 0.63 0.31 0.45 0.57 0.50 0.84 1.02 Type of 1.02 1.04 1.03 1.03 25

NOTE:

gOOesheath 800e sooe "8Soe 700e 700e Operating

Ambient temperature °c

(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 whep determining the current-carrying capacity of a cable.

(t) These factors are applicable ~~ly to rating in Columns 2 through 5 of Tables B.l and B.2.

.

- - -- 1.03 1.02 25 -1.021.03 0.86 0.83 0.97 0.84 0.49 0.39 0.48 0.68 0.89 0.42 0.86 0.96 0.88 0.41 0.58 0.71 30 60 55 45 40 80 75 90 35 65 85 95 0.98 0.72 0.62 0.91 0.93 0.95 0.87 0.56 0.69 0.79 0.94 0.80 0.90 0.92 0.89 0.85 0.76 1.01.04 0.96 0.77 0.82 0.55 0.64 0.43 70 50 1.02 85

Table A.5 Correction factors for ambient temperature where the overload protective device is a semi-enclosed fuse 85 0.90 80 70 60 70, sheath 105, sheath temperature

Ambient temperature

FC]

./

•

These factors are applicable only to ratings in columns 2 to 5 of Tables B.I ~d B.2. Correction factors for flexible cords and for 85°C or 150°Crubber-insulated flexible cables are given in the relevant table of current-carrying capacity.

Note:

ANNEX

B (NORMATIVE)

TYPE OF CABLE AND AMP ACITY Table B.1 Single-core P.V.C. insulated cables, non-armoured,

with or without sheath

(copper conductor) Current-carrying 2.5 cross-

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

capacity (Amperes)

II.~. ~\

..mV --Trefoil - Reference ac. ac. 2Of cables d.c. Of Of 2-2 cables, cables, single-phase Method Method 1 (dipped 1030 546 626 720 sing! e-phase -cables, Reference 12 (free air) touching touching Of -;.\ -14 ac. ac. Of d.c. 119 46 136 57 192 261 161 32 3••• 10.5 14.5 151 162 101 125 42 207 232 164 106 134 171 73 216 99 210 239 269 245 273 320 346 400 326 394 65 50 264 300 341 151 162 219 172 191 167 234 246 254 156 141 137 60 361 262 369 356 419 69 146 112 126 166 330 306 362 396 436 409 460 521 424 266 472 615 367 465 456 545 561 659 273 311 214 197 404 104 130 463 549 569 709 69 240 .mV -mV19.5 1138 1086 21 24 467 656 25 533 982 749 1166 826 732 634 652 792 635 920 1265 -mY 655 971 16 mV' 34 26 61 66 31 36 76 56 41 37 26 79 43 31154 10 52611 ac. 3 7 a4953 12 11 1149 1079 1337 91070 1216 1420 cables 4ac. Of cables d.c.flal Of 3 Of 15.5 11 mV 12 13.5 15.5 17.5 16 20 114 110 223 129 349 296 504 564 303 316 515 594 59 mV 27 694 679 723 776 1020 904 692 795 -mY 47 67 Of Vertical ac. 3trefoil Of 4cables cables d.c. flal HOfizontaJ 1058 i{ I~ 2 2 cables, three-phase single-phase spaced it conduit etc.) on a~ethod wall or3 in(endosed trunking ttYee-phase in I flal -Reference vertical) 33 n943 3single-phase cabI esphase trefoil ac. ac. flal flal and and and ttYee-phase touching 2 touching cables, ttYee spaced perforaled cable tray horizontal Of three phase and three-phase ~V Reference Method 4 (endosed in Reference

,I

3 Of 4 cables Method

11 (on a

'l',V -{

I,

p.•..O<,>.eoc•.••••• by - ooen"Ii-enclo~

E'•.•se.

see

A.6.2 o£ the preCace 'to this Ar1nex.

Table B.2 Voltage drop (per ampere per meter) Conductor operating temperature Reference 3etc. r0.25 and 0.068 0.059 0.150 0.160 0.165 11 (Flat andon 1 0.060 0.0520.130 0.130 40.33 (Enclosed -Methods in and x1.75 z)(z rr44 r0.29 r1.30 r1.75 -in 11 2.8 2.8 2.8 2.82.4 7.3 11 29 18 mV 29 44 18 7.3 conduit 9.5 29 18 7.3 25 44 11 9.5 or 59mV 7 4.4 20.39 4.4 4.4 3.8 0.29 0.195 0.28 0.190 0.180 0.27 0.185 0.28 0.63 1.75 1.25 0.46 0.93 1.80 1.30 0.54 0.69 0.97 1.50 0.49 0.95 0.65 1.80 0.41 1.10 0.55 0.80 0.50 1.50 1.25 0.43 0.57 0.95 0.66 1.10 0.25 0.31 0.28 0.30 0.29 0.24 1.25 0.81 0.56 0.93 0.47 0.63 1.30 0.56 0.72 1.80 1.55 1.00 1.10 0.93 0.47 0.80 0.84 0.63 1.75 0.41 0.60 1.25 1.50 0.26 0.55 0.170 0.165 0.155 0.175 0.85 0.61 0.63 0.061 0.050 0.24 0.25 0.24 0.175 0.26 0.053 0.068 0.180 0.086 0.105 0.145 0.23 0.36 0.45 0.35 0.31 0.39 0.25 0.32 0.110 0.1300.26 0.160 0.21 0.1950.26 0.086 0.094 0.105 0.130 0.072 0.34 0.30 0.36 0.26 0.160 0.175 0.190 0.150 0.27 0.23 0.22 0.26 0.25 0.27 0.33 0.22 0.29 0.37 0.086 0.081 0.105 0.1300.140 0.0720.135 0.41 0.47 0.37 0.120 0.150 0.185 0.160 0.40 0.30 0.37 0.24 0.31 0.32 0.21 0.::!8 0.27 0.29 0.31 0.33 0.23 0.24 0.25 0.066 0.26 0.115 0.150 0.185 0.08 0.100.22 0.12 0.14 0.076 0.093 0.140 0.135 0.145 0.155 0.36 0.41 0.32 0.160 0.165 0.22 0.23 0.40 0.24 0.25 0.175 0.27 0.20 0.22 0.25 0.27 0.29 0.31 0.26 0.042 0.060 0.052 0.145 0.140 0.21 0.20 0.22 0.21 0.053 0.28 0.29 38 15 6.4 mV 10xz0.20 84Reference Methods 0.82 1.50 0.42 1.10 0.55 0.29 1.10 0.80 1.50 0.160 1.55 1.10 0.48 0.32 0.32 1.15 0.86 1.55 0.170 0.160 0.26 0.29 0.22 0.24 0.34 0.27 0.26 0.160 0.081 0.32 0.100 0.1300.29 0.21 0.17 0.150 0.20 0.30 0.29 0.34 0.44 0.36 0.30 0.31 0.32 0.29 0.044 0.28 Method 0.098 0.185 0.40 0.51 touching) and Reference and 11 40.31 (clipped Methods or12 in 1,a direct on trays, 11 (spacedt) and 12 (in cables etc. in (Encl~ or on 2mV ~conduit (flat spaced t)atrefoiQ

or cross-

touching) 2Reference cables Reference Methods Method 12 3 ac. wall ')- single-phase

3

or

4 cables

- thr~phase

ac.

~

~ ~

t

•

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

Reference Methods

1

: 70°C

Table B.3 Multicore P.V.C. insulated cables, non-armoured (copper conductors) Current-carrying capacity (Amperes): -cablet or d.c. cablet 1I fourfourcable t or or d.c. or Icore 470 Reference Method in on acable, wall orthreeceiling,3or(enclosed in -19.5 11a.c. three three-core three-core 597 715 557 32 25 11 11099 139 167 16.5 43 219 246 57 9263 7566 192 291 1413 16.5 14.5 16.5 133 111 136 112 119 213 201 256 232 125 39 69 90 1 30 29 223 2 13 10 166 46 60 70 52 62 94 144 23 36 34 20 25 43 344 294 461 297 430 464 497 236 262 57 76 101 206 276 326 259 116 153 160 40 24 51 196 225 319 379 255 364 434 341 403 164 179 514 593 99 23 15 22 196 17 72 61 96 7.5 2 4150 3634 95 7 8A 402 334 11.5 13.5 63 65 299 27 392 339 394 149 223 146 119 32 41 17.5 96 d.c.conduit 1core three-core G cablet or or 1threefourA 530 A 12.6 core cable, core cable, threecable or Reference Method 13 Reference phase a.c. (free air)Method 11 (on a perforated Reference 1 (clipped direct) trunking) t 1Reference two-core cable Method 4t.t (enclosed intray), anMethod single-phase a.c. single-phase two-core cable 11phase two-core cable a.c.. phase a.c. single-phase a.c. single-phase a.c.

t

Ambient temperature : 30"C Conductor operating temperature: 70"C 1 two-core cable t,

With or without protective conductor. Circular conductors are assumed for sizes up to and including 16.0mm2• Values for larger sizes relate to shaped conductors and may safely be applied to circular conductors. Note: Where the conductor is to be protected by a semi-enclosed fuse, see A.6.2 of the Preface to this Annex.

~--------------------SECTION 4: CONDUCTORS

.Table B.4 Voltage drop (per ampere per meter) Conductor operating temperature : 70°C

x0.34 z.135 Conductor 0.135 0.100 0.185 0.21 0.185 0.145 0.160 0.155 0.115 '0.105 0.145 0.165 0.24 0.29 0.150 0.130 0.25 0.130 0.25 0.190 0.180 0.23 7.3 11 2.8 4.4 29 18 11 7.3 18 4.4three-phase 9.5 2.4 3.8 6.4 25 15 0.55 0.26 0.33 1.50 0.80 1.10 0.41 0.65 0.94 1.75 1.25 00.165 0.155 0.35 0.81 1.10 .145 .130 .135 .140 0.63 1.75 0.93 0.63 1.75 44 0.29 44 0.41 0.50 0.43 0.46 0.125 0.145 0.150 0.21 29 2.8 Three-or four-core cable 0.170 0.140 0.29 1.50 0.30 1.25 1.25 mV 38 0.47 0.36 0.93, 0.57 -~ mV .J...0.21 Q mV 0.38 Two-core phase cable a.c. singlea.c. Two-core cable d.c. mm2


EBCS-10 1995

93

\0 ~

,

Table B.S Single-core armoured P.V.C. insulated cables, non-magnetic armour (copper conductors)

Current-Carrying

Catpacity

(Amperes): Conductor

cross-

Note:

flat spaced 296 7720 1041 1441 447 1008 1218 919 843 763 687 525 594 624 976 710 943 891 669 893 805 622 313 269 723 575 469 399 490 465 492 648 1627 816 975 777 1390 728 1174 809 676 721 673 285 338 340 357 327 385 396 415 383 578 616 719 748 640 618 632 674 851 885 525 548 422 456 515 550 593 528 566 547 808 967 872 771 997 245 193 205 179 259 225 212 230 216 217 286 279 294 287 238 10 21685 4349 3 9332 5678 11 a.c. or d.c. 342 1035 737 8fO 360 309 401 668 567 501 945 856 731 280 324 657 707 489 511 425 568 905 824 231 886 229 272 189 181 12 11 on a Vertical cables a.c. a.c. trefoil flat or or and and 44flat A 229 Horizontal 33 cables 2 cables, ,263 Vertical flat Reference cables, 2Method cables d.c. 2Horizontal cables, A Vertical, three~phase three-phase shinglephase a.c. 3cables or 4 cables, three-phase flat spaced perforated cable tray touching touching Reference 1single-phase spaced single-phase 2Method a.c. Horizontal

a.c.

Reference Method 12 (free air)

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

operating

temperature:

700c

Table B.6 Voltage drop (per ampere per metre) Conductor operating temperature: 70°C x0.24 x0.92 z0.95 zrx x0.190 r0.079 r0.20 r0.135 Reference 1 0.86 0.97 0.190 0.26 0.72 0.25 0.68 0.32 0.58 0.175 0..28 0.170 0.24 0.50 0.27 0.45 0.30 0.23 0.160 0.41 0.29 0.34 0.68 0.30 0.29 0.52 0.28 0.500.33 0.35 0.43 0.37 0.27 0.21 0.84 0.22 0.21 0.20 0.195 0.43 0.190 0.38 0.30 0.180 0.450.44 0.180 0.320.30 0.270.25 0.170 0.580.57 0.42 0.34 0.23 0.66 0.51 0.120 0.091 0.175 0.80 0.42 0.165 0.125 0.145 0.175 0.30 0.47 0.24 0.29 0.39 0.31 0.095 0.93 0.64 0.48 0.160 0.32 0.140 0.30 0.120 0.27 0.20 0.21 0.21 0.195 0.170 0.24 0.155 0.28 0.26 0.23 0.140 0.135 0.130 0.160 0.22 0.63 0.46 0.086 0.068 0.053 0.145 0.180 0.105 0.36 0.29 0.23 0.20 0.042 0.190 20.22 3mV 4mV Reference 1, Method 0.180 0.57 0.165 0.37 0.28 0.31 0.440.27 0.390.22 0.32 0.22 0.62 0.50 0.34 0.180 0.165 0.370.36 0.175 0.165 0.160 0.155 0.820.79 0.29 0.105 0.082 0.140 0.56 0.160 0.170 0.165 0.20 0.28 0.190 0.79 0.59 0.40 0.34 0.26 0.105 0.091 0.026 0.25 0.29 0.23 0.22 0.180 0.160 0.23 0.24 0.195 0.185 0.180 0.21 0.150 0.145 0.145 0.140 0.155 0.21 0.93 0.195 0.165 0.195 0.170 0.24 0.22 0.21 0.26 0.24 11 and 512 etouching) 7V 12 (in trefoil mV m mV cables - single-phase a.c. Methods Reference Methods 12 Methods mV Reference Method 12 and 11 and 11 (Touching) (Flat and (spacedt) 3 or 4 cables - Reference three-phac;e a.c. 2 cables d.c. (Flat spacedt)

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

\0 VI


Table B.7 Multicore armoured P.V.C. immlated cables (copper conductor) Current-carrying capacity (Amperes): Ambient temperature: 30°C Conductor operating temperature: 700C " Conductor

a.c. or d.c. 1single-phase two-core cable, 267 269 332 110 128 356 190 516 231 38 45 35 41 33 53 562 3472 ,83 222 118 175 145 89 163 445 310 251 378 510 207 241 590 290 336 469 97 77 102 151 157 125 409 476 291 267 386 306 439 348 592 683 540 621 547 49 A 26 19 31 42 18 21 28 1A three Reference or four Method 1 Method tray), or aReference Method 13 (free 135 405 58 192 22 A 25 core cable, (Clipped direct) 11 (on three-phase a.c. perforated horizontal or vertical cable 1 three or four Reference three-phase core a.c. cable, air)

Note:

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

96

EBCS-10 1995



Table B.8 Voltage drop (per ampere per metre) Conductor operating temperature: 70·C Conductor r 0.34 x0.26 z0.185 z1.75 x.21 0.41 1.75 1.25 0.145 0.140 0.135 Q.1300.29 0.80 1.50 1.10 0.125 0.33 0.160 0.170 0.165 0.81 1.10 0.155 1.25 0.38 0.100 0.30 7.3 0.63 0.145 1.75 11 4.4 0.36 18 4.4 7.3 29 18 11 2.4 3.8 6.4 25 229 3 9.5 4 threethree-phase 0.94 0.50 0.65 0.29 0.24 0.21 0.130 0.41 0.21 0.165 0.130 00.155 0.150 0.35 0.155 0.57 0.25 1.50 0.160 0.150 0.145 0.63 0.93 0.47 0.25 0.155 0.115 0.190 0.93 0.46 0.105 0.180 1.25 2.8 0.29 0.23 0.185 15 0.55 0.43 mV mV or four-corea.c. cable, mV phase a.c. 2.8 Two-core cable singled.c. Two-core cable 1


EBCS-10 1995

97

\0

Table B.9 Single-core cables having thermosetting

00

insulation, non-armoured,

with or without sheath

(copper conductors) Current

carrying capacity (Amperes): Conductor

I area

--and -phase Trefoil .--10 cables flat threeand 1288 1443 900 683 783 touching orflat ac. three-phase direct) -trunking -ac. ..or Reference Method (clipped a.c. or 1130 1065 1044 1228 1358 1581 1214 1520 990 1191 1423 1069 820 1485 1323 793 868 584 666 904 1150 764 1033 1338 1179 1275 1436 1115 849 936 994 149 189 10091 228 124 341 263 300 400 2423 126 228 240 290 336 30 111 375 445 426 189 135 209 170 293 308 351 270 205 355 330 235 143 183 138 156 176 195 436 495 385 34 306 573 410 701 606 500 358 511 168 246 274 214 318 259 389 111 163 171 203 299 379 453 26 31 476 328 824 886 794 681 743 493 711 769 630 590 524 570 370 600 651 530 579 279 341 130 140 398 644 461 14 13 17 19 15 1817 22 25 23 19 33 58 76 109 53 95 40 71 81 70 46 63 74 85 35 2459 3439 859 1n5 1349 12 11 7 43 51 45 54 3 342d.c. cables orflat trefoil ac. trefoil ac. ac. or threed.c. 915 973 Vertical Horizontal flat 3 orReference 4 158 226 413 505 545 215 268 730 686 326 161 17.5 41 99 3 3three-phase or or 61671 95 4cables cables cables cables 2conduit cables in onMethod a wall1 Method or in . 12 (fee air)Reference Method 11 (on a 3 cables, 2ac. 2 cables, cables, phase three-phase ac. single phase spaced threethreesingle phase phase .rt33 trunking etc.) 3 (enclosed single-phase Reference Insulating wall etc.) 4 (enclosed and touching ac. or orMethod d.c. d.c. flat flat 3 or 4 cables orReference vertical in conduit in thermally single-phase and touching single-phase perforated cable tray horizontal

Ambient operating

temp~rature: temperature:

30°C 90°C

spaced,

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 Columm 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 ~~>~':..~e.::...~} ..~?.?_~!_~~:.~~~~::,~:';.:.~~~re a conductor operates at a temperature exceeding 7cPC. it shall be ascertained that the equipment connected to the conductor is suitable

Note:

Table B.10 Voltage drop (per ampere per meter) Conductor operating temperature: Reference Reference Methods 3 and 4single-phase 0.072 0.150 0.170 0.1300.145 0.0630.150 0.165 touching) direct or on trays, -and -0.140 0.955 0.1300.140 r rrxr0.31 rMethods z0.28 x1.65 z1.15 x0.34 z0.22 z0.062 x4(Enclosed 0.37 0.165 0.190 0.29 0.180 0.25 0.155 0.26 0.75 0.28 0.58 0.27 0.24 0.150 0.48 0.43 0.23 0.140 0.37 0.33 1.05 1.35 0.180 0.175 0.170 0.165 0.27 0.26 0.27· 0.73 0.56· 0.41 0.33 0.36 0.99 0.89 0.65 0.25 0.49 0.42 0.24 1.20 1.35 0.68 0.26 0.39 0.49 0.195 0.25 0.0860.155 0.1050.155 0.10 0.155 1.60 0.87 0.61 0.37 0.45 0.25 0.26 0.24 0.1300.155 0.20 0.59 0.43 0.28 0.24 0.87 0.125 0.088 0.60 0.35 0.44 0.29 0.185 1.35 0.70 0.51 0.41 0.33 0.27 0.175 0.140 0.100 0.120 1.00 0.99 0.68 0.49 0.056 0.072 0.093 0 0.21 0.155 0.120 112 0.39 0.32 0.25 .190 .35 0.90 0.65 0.42 0.32 1.15 0.180 0.175 0.170 0.165 0.31 0.29 0.28 0.160 0.27 1.60 1.15 0.87 0.62 0.46 0.28 0.38 0.32 0.43 0.28 0.20 1.35 0.71 0.43 0.52 0.25 0.36 0.30 0.22 1.00 0.34 0.28 0.22 0.43 1.60 1.15 0.86 0.59 0.21 0.22 0.25 0.090 0.175 0.185 0.170 0.135 0.110 0.085 0.170 0.078 0.23 0.29 0.25 0.071 0.068 0.110 0.1400.195 0.135 0.165 0.24 0.064 0.240.045 1.90 1.85 0.23 1.85 1.85 0.190 1.85 0.055 0.059 0.155 0.165 231 0.23 0.24 0.054 0.047 0.050 7.9 46 4.7 2.9 19 19 31 12 46 4.7 2.9 31 7.9 4.7 2.9 19 31 4.0 37.9 446 512 0.145 0.47 1.00 0.32 0.31 0.1~5 1.15 0.86 0.150 0.100 1.15 0.23 0.50 0.37 1.15 0.86 0.59 0.34 0.22 0.110 0.074 0.170 0.098 0.088 0.27 0.24 0.135 0.1350.175 0.1350.150 0.140 0.160 0.160 0.22 0.180 0.21 1.85 1.60 20.1600.195 cables, a.c. 89610 7 4.0 16 40 27 6.8 4.7 2.5 3 mV mV Reference Methods Reference 1 Method and 11 conduit etc. in or(Spaced mV 12 (Flat 0/2.7 1.65 1, 11, t0.160 )0.170 and 12 (In trefoil) 12 spacedt) (Flat touching) 0.24 Cable aand wall) Reference Method s 1.60 d.c. oninconduit 1 11etc. (Clipped on a wall) in or

3 or(Enclosed 4 cables- in three-phase .a.c.

\0 \0 t Spacing larger than those specified in Method 12 (see Annex A, Section B) will result in larger voltage drop'

90°C

-oo Table B.11 . Multicore, non-armouroo cable having thermosetting insulation (copper conductors) Current-carrying

capacity (Amperes): Conductor

~

Note:

Ambient temperature: 30"C operating temperature: 90"C

-three-or 1 1456 threeorfourfourthree-phase phase a.c. a.c. or -33 Reference Method 3 in conduitor on acable wallthreeor ceiling , or(enclosed in threetrunking) 107625 d.c. 1phase two-core 1d.c. two-core 4146 9A 8276· 7 119 221 175 9180 384 459 246 298 158 127 100 346 399 538 621 192 220 .253 115 183 145 121 225 290 741 289 352 185 149 410 473 329 542 641 99 386 442 269 209 171 138 295 164 2 130 109 89 68 382 268 259 424 506 346 599 396 455 229 197 278 147 119 322 371 500 576 179 227 96 00 741 865 667 536 d.c. core cable 1265 two-core 1 two-core 563803 305 334 532 328 441 1 128 340 693 1 54 05 98 94 a.c. A A A core threecore A A cable singleMethod Reference 13 (free air)Method 11 (on a phase orcable perforated cable orcable Reference Reference 1 (clipped direct) threeor inMethod Reference Method an tray) four-core cable 4 1(enclosed phase phase a.c. cable singlecablea.c. single-

(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 the equipment connected to the conductor is suitable for the conductor operating temperature.


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

Conductor operating temperature

: 90°C

r0.150 z1.90 x0.52 z0.21 Conductor 0.145 0.145 0.140 0.175 0.130 0.125 0.86 0.43 0.59 0.115 0.34 0.28 0.22 0.195 0.125 0.24 0.42 0.120 0.35 0.29 0.69 1.00 0.170 0.185 0.21 0.45 0.37 0.30 0.60 0.87 0.50 0.67 0.99 0.40 0.32 0.26 0.130 0.160 0.2000.98 0.120 0.155 0.49 0.67 0.195 0.39 0.31 0.25 0.155 0.135 0:140 1.15 1.60 1.35 1.85 1.35 1.85 2.9 2.9 0.26 2mVmV 3 2.5 4mV 0.160 1.65 1.35 Three-or four-core cable 1.15 phase three-phase a.c. a.c. Two-core cable singleTwo-core cable d.c.

1


EBCS-10 1995

101

o

•.....

tv

Table B.13 Single-core cables having thermosetting insulation, non-magnetic armour (copper conductors) Current-carrying .capacity (Amperes): or&3 d.c. flata.c. cables trefoil singletouching Reference Method 3cables or or 414 cable 2 10 3A220 4phase 567spaced 11 12 A 303 237 277 357 293 322 358 284 266 282 232 253 288 349 331 285 222 1082 1170 1137 1016 1032 1314 1146 1246 1204 557 1345 488 425 962 496 791 717 853 662 755 579 1261 437 383 333 899 792 1055 2100 477 889 929 1266 1474 1528 1092 943 805 842 1744 1809 1155 815 714 749 612 689 587 688 614 643 1238 2026 462 516 600 539 449 497 446 412 436 352 389 425 1094 797 871 940 767 904 700 755 810 906 1042 666 715 782 1041 524 574 618 660 1289 566 510 549 575 504 405 519 485 426 393 861 961 1110 989 935 851 987 848 923 1 1214 815 918 720 625 529 463 402 346 027 93270 Horizontal Vertical Horizontal flat flat threea.c. 3:J7 A A 656 992 978 Horizontal Vertical 356 1119 and cables, ,367 phase 21139 cables a.c. single-phase a perforated Reference Method 11(on flat spaced or 4&& 3 cables,tray) three-phase flat spaced or d.c. flat phase a.c. singleflat threephase a.c. touching

onductor

Note:

Ambient temperature: 30"c Conductor operating temperature: 90"C a.c. 2 cables d.c. Reference Method 12 (free air)

(i) Where the conductor is to be protected by a seini-enclosed fuse, see A.6.2 of the Preface to this Annex. (ii) Where a conductor operates at a temperature exceeding 7Cf'C, it shall be ascertained tbat the equipment connected to the conductor is suitable for the conductor operating t.empera'turc.

Table B.14 Voltage drop (per ampere per metre) Conductor operating temperature: -

t

.

x0.145 x0.53 x0.21 r0.080 r0.69 z0.195 zr0.33 x0.24 z.180 r0.60 0.105 0.180 0.175 0.190 0.175 0.20 0.155 0.27 0.23 0.150 0.165 0.190 0.125 0.180 0.170 0.135 0.24 0.140 0.155 0.29 0.25 0.31 0.26 0.140 0.27 0.30 0.180 0.125 0.145 0.105 0.092 0.090 0.093 0.073 0.115 0.045 0.170 0.38 0.35 0.31 0.23 0.36 0.24 0.30 0.29 0.41 0.34 0.190 0.28 0.30 0.185 0.29 0.175 0.27 0.37 0.51 0.30 0.45 0.41 0.28 0.45 0.160 0.32 0.45 0.25 0.28 0 .150 0.51 0.33 0.27 0.170 0.21 110.056 0.155 0.195 0.31 0.25 2and 37mV 0.84 0.44 0.98 0.62 0.84 0.58 0.195 0.21 0.70 0.200 0.90 0.52 0.32 0.62 0.47 0.87 0.75 0.71 .25 0.68 0.99 0.49 0.98 0.67 5mV 64Reference 0.092 0.165 0.086 0.125 0.195 0.29 0.26 0.21 0.43 0.170 0.165 0.180 0.180 0.160 0.195 0.21 0.28 0.34 0.44 0.39 0.26 0.23 0.135 0.145 0.21 0.150 0.39 0.25 0.33 0.29 0.51 0.165 0.35 0.40 0.25 0.22 0.22 0.155 0.33 0.170 0.195 0.20 0.38 .24 .23 0.86 0.60 0.59 0.46 0.49 0.65 0.88 0.170 0 0.24 1.00 0.55 mV Reference Methods 0.130 12(Spacedt) Reference Method mV Methodt)12 . Reference Methods 1Reference 2 cables a.c. 1. Methods a.c. 0.410145 ( (in Flattrefoil spaced 3 or1 -4 single-phase cables - three-phase 2 12 cables and 11 (Flatd.c. touching) 150

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

90"C./

singlecable, Method 1 (clipped direct)


Table B.1S Multicore armoured cables having thermosetting insulation (copper conductors)

Current-Carrying

Capacity (Amperes): Conductor

,

520 11 three-or three-or fourfouror phase a.c. 732 599 636 546 87 31 66 39 52 78 5685 304 251 338 92 472 463 406 607 51 15 628 98 673 847 728 34289 544 23456727 115 90 29 73 42 53 25 33 49 62 110 36 A 228 124 154 238 335 152 188 354 291 410 131 162 187 353 197 219 279 146 180 386 441 539 23 99 A 94 A1 two-core 1 .5 a.c. three-phase cable, singlea.c. cable tray} or Reference Method 13

Note:

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

perforated horizontal or vertical air) 11 (on d.c. 1 two-core Reference (free Method core cable,

(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 7fJ'C, it shall be ascertained that the equipment connected to the conductor is suitable for the conductor operating temperature.

104

EBCS-10 1995

ETHiOPIAN BUILDING CODE STANDARD


Table B.16 Voltage drop (per ampere per meter) Conductor operating temperature: 90°C

,

Conductor 0.120 1.60 0.115 Two-core x0.140 x 0.160 r0.86 z0.185 0.16' 1.85 0.59 0.28 0.99 0.140 0.175 0.13 0.20 2.9 0.43 1.15 0.22 0.34 1.35 0.67 0.50 0.32 0.26 0.40 0.170 0.125 0.145 0.21 0.24 0.140 01z1.65 .21 0.120 0.155 0.195 1.85 Three-or four-core cable 7.9 12 4.7 19 2.9 12 7.9 4.7 19 a.c. 10 27 16 2.5 6.8 4.0 1.135 0.155 1.35 .15 0.135 0.130 0.125 0.195 0.69 0.52 0.150 0.29 0.42 1.00 1.90 .300.25 .370.31 .87 .60 .450.39 0.67 0.49 231 331 d.c.Cable 4three-phase .26 mV mV 0.98 a.c. 1.35 phase 0.35 Two-core cable singlemV cross-

1


EBCS-10 1995

105

/

Table B.1? Ssingle-core non-armoured cables having 8SoC rubber insulation (copper conductors) Ambient temperature: 30°C Conductor operating temperature: 85°C

Current-carrying capacity (Amperes): ----cables, - ac. 219.5 phase phase cables, ac. singleor or d.c. d.c. Reference Method 11 (on perforated flat and 2-192 single .996 -or 27 17 19 15 A 40 72 30 42 45 36 75 81 63 31 34 242 293 190 157 127 339 372 719602 835689 215 167 332 384 827 946 164 177 138 133 143 112 254 274 213 258 308 298 357 411 442 334 755 199 865 229 989 189 293 356 412 475 860 153 1081919 154 303 370 431 499 786 929 174 211 269 327 379 437 798 918 140 320 373 432 680 167 134 204 262 799 96 108 85 100 52 54 59 510443 1088 519 379 469 553 607 636 695 791 1143 542 639 573 1263 679587 499 589 1062 495 1060 2593506 345A46 6AA 7 9 22 23 25 A 428 975 735 8235 3 or4touching 4Method cables or ad.c. or 3 or 4 4 cables 679 Reference 3 cables, three3 and (enclosed in touching orflat trefoil 3A17.5 cables threephase phase trefoil ac.ac. three-phase ac. cable tray)Horizontal 3 or phase ac. or d.c. or trefoil 2 cable singlecables spaced horizontal three-phase ac.flat Reference Method 1(clipped flat phase and touching ac.threeReference Method direct) 12 (free air) or vertical

Note:(i)

(ii)

or Vertical

single-phase

ac.

Where the conduc~or is to be protected by a semi-enclosed fuse, see A.6.2 oft the Preface to Annex .. Where a conductor operates at a temperature exceeding 70"C ,it shall be ascertained that the equipment cottnected to the conductor is suitable for the conductor operating temperature.

Table B.18 Voltage drop (per ampere per metre)

.

Reference Methods 1 director On and 11 (clipped 26 16 4.0 2.5 (Flat spaced )trays, 40 6.7 10 zxz xz0.24 xz z0.27 x0.25 z0.37 x1.200.95 r0.87 r1.30 r0.58 r0.100 --trefoil -0.089 cables 0.24 0.25 0.073 0.085 0.067 0.073 0.22 0.155 0.21 0.077 0.300.072 0.110 0.105 0.091 0.140 0.24 0.26 0.31 0.140 0.29 0.125 0.175 0.120 0.30 0.110 0.160 0.25 0.20 0.29 0.135 0.150 0.170 0.135 0.150 46 0.170 0.21 0.28 0.26 0.27 0.34 0.32 0.23 0.30 46 . Reference 0.155 0.195 0.155 0.195 0.31 46 0.135 0.165 0.22 0.23 - single-phase ac. 0.28 0.175 0.170 0.155 0.24 0.51 0.37 0.43 0.33 0.32 0.65 0.27 0.41 0.30 0.88 0.23 0.28 1.15 1.65 0.650.48 0.72 0.56 0.40 0.47 0.45 0.52 0.900.65 0.36 0.370.190 1.35 1.00 1.85 1.651.30 0.60 0.44 0.29 0.35 0.23 1.15 1.60 0.57 0.84 0.22 1.15 1.60 0.27 1.85 0.57 0.43 1.15 0.84 1.60 0.22 1.60 0.68 0.40 1.35 0.51 0.27 1.80 0.30 0.38 0.25 0.35 1.85 1.60 0.62 0.31 0.69 0.360.31 0.430.39 0.300.25 1.35 1.15 1.60 0.170 0.175 0.155 0.150 0.165 0.160 0.49 0.25 0.31 0.29 0.25 0.97 0.180 0.74 0.39 0.49 1.30 1.40 1.85 0.38 0.49 0.97 0.45 0.86 0.26 0.60 0.27 0.22 0.57 0.84 0.190 0.195 0.20 0.52 0.23 0.22 0.24 0.99 31 40 31 20.28 231 3 7 5 4 18 18 18 26 7.7 4.6 12 12 4.6 7.7 12 4.6 7.7 10 6.7 2.9 2.9 2.9 0.29 0.082 0.27 0.155 0.24 0.22 0.29 0.089 0.105 0.130 0.085 0.115 0.115 0.23 0.26 0.28 0.135 0.22 0.26 0.100 0.165 0.28 0.097 0.21 0.24 0.185 0.26 0.25 0.180 0.33 0.29 0.145 0.195 0.22 0.170 0.26 0.22 mV mV 0.23 0.28 0.29 0.31 0.26 0.48 0.91 1.20 0.66 0.34 0.42 0.34 1.15 1.85 1.00 0.32 0.27 0.30 0.66 0.31 0.42 1.90 1.05 0.43 40 0.185 d.c. Reference Methods 9 6 8 26 16 4.0 2.5 mV Reference Methods mV Spaced )0.175 .0.25 1,11, Meth~ and 12(in 12 1 2 cables touching) touching) and 11 (Flat 0.32 Reference Method 3(Enclosed inReference conduit Reference Method 12 etc. in 3(Enclosed or on aM~hod wall) in conduit

s·

t

Conductor operating temperature: 3 or 4 cables - three-phase ac.

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

85°C

o00

•....

Table B.19 Multicore, sheathed and non-armoured cables having 85°C rubber insulation (copper conductors)

Current-carrying capacity (Amperes):

n In

553 470499 211185 254222 292 256 329 269 310 272 287 237 555 675 593 509 587 436 515 437 359 167147 2439 201 409 381 312 34482 174 7 151 Reference Method 3 Reference (enclosed) 114100 139122 136 144 168 88 123 94 6.5 2118.5 2925 14.5 32 16 20 34 23 17.5 320 368 413 287 438 326 383 48 38 66 87 58 37 43 33 55 81 76 59 40 52 71 222 186 103 109 5A213 117 6A 19.5 25 28 18 A 22 30 11phase threethreeor or four-core 48 46 66 1 threeorcable. four-core three.. J II 333 1 two-core phase cable. ac. phase ac. or four-core d.c. ac. or d.c. ;359 636 ReferenceMethod Method111 (on (clipped direct) cable tray). or cable. 1 1AA two-core two-core three-phase phase cable ac. singleac. cable. a perforated cable singleII 1

Note: (i)

(ii)

Ambient temperature: 300C Conductor operating temperature: 85°C Refrence

Metthod

13 (free

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

air)


Table B.20 Voltage drop (per ampere per meter) Conductor operating temperatures:

,

19 Conductor 0.25 Two-core cable r0.155 z0.170 z0 x0.26 x 0.66 0.99 0.68 1.35 0.165 0.150 1.15 0.84 0.86 0.59 .58 0.97 0.65 0.95 1.85 0.175 1.60 46 0.22 0.42 0.52 0.160 0.185 0.45 .34 .43 0.49 0.38 12 0.35 0.135 .27 0.31 0.25 0.30 7.7 2.9 4.6 0.145 0.140 1.30 1.30 1.85 1.80 231 3mV 4 19 16 0.150 0.160 0.130 0.130 0.22 0.36 .170 0.195 0.155 0.39 0.190 0.150 0.48 12 0.30 0.130 0.30 .22 0.25 7.7 2.9 single-phase 2.5 46 40 mV 31 26 10 6.7 4.6 4.0 mV cable d.c. Two-core

a.c.

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

85°C cable three-

1


EBCS-10 1995

109

..


Table B.2l 60°C rubber-insulated flexible cables, other than flexible cords

.

Single-phase or d.c. - a.c. core 394 ,.---2738 291 124 102 644 861 192 255 222 158 single cables cable -13 541 394 471 347 30 175 26 302 140 73 63 258 83 297 4 39 51 34 A A 47 fiveA 216 three-core, four-core Single phase Three-phase a.c.core or d.c. a.c. or without protective conductor 1 two-core cable with or

343 Conductor

Notes:

Current-carrying capacity: Ambient temperature: 30°C (Amperes): Conductor operating temperature: 60"C

(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 cylindrical cable 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:

-zzxTwo-core - 0.068 - -- -0.170 0.83 0.57 0.42 1.10 0.33 0.27 0.090 0.22 0.115 -0.079 -- 0.135 -0.49 r zx-1.80 Conductor x0.130 1.55 1.85 0.175 1.80 4.6 2.9 4.6 2.9 0.180 0.93 1.32 0.36 0.30 0.91 0.38 0.150 0.27 12 12 0.20 0.195 0.67 0.53 0.140 0.64 0.49 7.8 7.8 0.150 1.55' 0.185 0.21 0.130 0.190 0.195 10r 4.0 2.5 0.170 0.21 0.185 0.135 0.145 0.125 0.24 0.43 0.36 0.84 1.15 1.31 0.31 0.38 0.31 1.31 0.91 0.155 0.190 0.26 0.32 0.20 0.25 0.099 0.58 0.44 0.64 0.175 0.21 0.120 6.7 mV mV mV cable d.c. a.c.mV 0.25 mV cable three-phase a.~ 1 three-core, four-core or five-core Two-core cable single-phase Single-phase a.c. t

t

Larger voltage drop will result if the cables are spaced.

d.c. 2 single-core cables touching

60"C


Table B.23 8S·C or lS0·C rubber-insulated Current-carrying

flexible cables

capacity (Amperes): Conductor \

Conductor cross-

CORRECTION

.

741 dc. 41 2131114 47 3AA 4476 262 140 397 348 240 99 73 64 86 192 414 645 540 467 537 36 297 354 orA Threl-phasl sing/I-phasl a.c. 303 cors, cors cable} four-cors or(1five(1 53 two-cors cable, with touching or without Single sing/I-cors protlctivs phasla.c. a.c. cables or thrsldc. 216 2170

30°C 85°C

1190 1017 885

FACTOR FOR AMBIENT TEMPERATURE

85°C rubber-insulated cables: Ambient Temperature (0C): Correction

Ambient temperature: operating temperature:

factor:

150°C rubber-insulated

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

cables:

Ambient Temperature (0e) Correction factor:

35 to 85 90 95 100 105 110 115t 120t 125t 130135t 1.00 0.96 0.92 0.88 0.83 0.78 0.73 0.68 0.62 0.55 0.48

Ambient Temperature (0e): Correction factor:

140t 145 0.39 0.28

t

Refer to notes for Table B.2!.

112

EBCS-10 1995


Table

B.24 Voltage

drop

(per ampere per

meter) Conductor

operating

temperature:

85"C

- z0.185 0.29 0.61 0.145 0.46 0.36 0.24 1.20 0.105 0.130 0.084 0.90 - 0.190 cables touching - single-core r 0.21 r0.27 x0.20 z x-zx-0.180 Conductor 0.165 0.53 0.27 2mV cable 3 --three-phase 0.33 0.130 0.190 8.4 0.125 13 0.33 0.41 0.21 13 0.70 0.140 0.70 0.99 0.99 0.41 0.53 0.170 0.135 0.195 0.098 0.175 0.150 2.00 2.00 1.42 2.0 5.0 5.0 0.175 3.1 3.1 4mV 0.38 0.130 0.28 0.72 0.185 0.20 0.32 0.22 0.63 8.4 7.3 mV 0.125 0.25 0.46 0.33 0.56 00.170 .195 0.48 0.39 0.27 0.145 1.01 0.91 1.42 1.700.150 1.43 0.21 1.70 1.20 4.3 0.22 0.073 2.7 11 a.c. 52-three-core, core a.c. Two-core 1mV cable single-phase four-core d.c. Single-phase a.c.tor flve1 two-corecables or single-core 1

Note:(i) The voltage drop figures given above are based on a conductor operating temperature of 85°C and are, therefore, not accurate when the operating temperature is in excess of 85°C. In the case of the 15

Table

B.25

Conductor crosssupportable by

Current-carrying

capacity

[Amperes] (fleXIble cords)

5342520 Current-carrying -225 25 16 32 16 10 10 3A6Three-phase 313 6flexible Maximum capacity mass twin cord A kg a.c. Single-phase a.c.

Where cable is on a reel, see notes to Table B.21. CORRECTION

FACTOR FOR AMBIENT TEMPERATURE

60°C rubber and p.Y.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.oJ.r. sheath or a heat-resisting p.Y.c. sheath and for 85°C heat-resisting p.Y.c. cords: Ambient Temperature Correction factor:

(0C): 35 to 50 55 60 65 70 1.00 0.96 0.83 0.67 0.47

130 145 140 135 0.40 0.57 0.71 0.82 0.92 175 170 165 0.42 0.60 0.74 0.85 0.96 ISOOC 160 rubber cords:

1.00 155 125 150 Ambient Temperature (°C):35 to 120

114

EBCS-10 1995



Table B.26 Voltage drop (per ampere per metre) Conductor Conductor cross-

operating

temperature:

600Ct

- . 2:7 10 32 12 19 54 40 80 46 37 93 62' mV m d.c.2318 orV single-phase Three-phase a.c.

1

The tabulated yalues are for 60"C rubber-insulated and p.y.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.y.c.-insulated: 150"C rubber-insulated: 185°C glass fibre:

1.09 1.31 1.43


EBCS-10 1995

115

Table B.27 Mineral insulated cables bare and exposed to touch (see Note ii below) or having overall covering of P.V.C. (copper conductors and sheath) Current-carrying capacity (Amperes): Reference Method 1 (Oipped Direct) 11

Note:

-three----1loaded a.c. cables cable four-core all in cores flat formation, phase -72 -Asingle-core 65 48 37 29 40 35 249 26 31 23 19 10.0 31 28 21 -112 .loaded 18.5 15 86 169 64 47 70 52 55 37 41 32 26 110 120 94 16.5 26 38 264 18 14.5 11.5 2 371 207 9.5 3 515 98.5 4 616.5 87133 19.5 21 21 14.5 23 12.0 1 85 A A A 286 17 13 10 327 137 181 457 434 three-core trefolle or 1 28 19.5 25 16.0 17.5 221 392 22 cables in 1 four-core 13 2816 single core 92 A A 303 346 147 77 cores cable all cable loaded cores all 1 1 seven-core twelve-core A 202 514 57 45 19.5 25 34 340 102 163 388 cable, three247 440 296 phase a.c. 3 loaded two-core loaded cable all 3threecores cable cores phase a.c. orsingle.core cable, a.c. 3phase single-core

Ambient temperature: 30°C Sheath operating temperature: 70C 1 nineteen-

i) For -single-core cables. the sheaths of the circuit are assumed to be connected together at both ends. n_ hloe ••.~cx-r.c>""'.cd 1-~ 1-c->'L."" •.•.• 1-he:;; tnhl...:llr.tec::1 .••.••. al'U1cs. ,..h~,-"Id be> m •.•It.iplie.;:.l nv 0.9_

"'"£.-.t:»le :B-27 lVIineral ins&.alat:.edcables bare a •..• d. exposed to to&.ach(see Note ii bela,"",>or havi •.•. g overall coveri •..• g or (copper conductors and sheath) (conte'd) Current-carrying capacity (Amperes): Reference Method 11 (On a perforated cable tray, horizontal or vertical) -

Note:

.. --cores -core core 246 164 472 202 294 335 380 424 105 135 32 43 35 80 25 47 59 19 -142 -1 -34 -8cores -cores 1 threeTrefoil core core 267 three215 182 21 17 36 30 27 3 0 92 37 30 399 32 28 39 97 552 47 364 466 120 101 40 35 308 116 4 45 135 524 147 223 187 279 153 229 17.5 21 22 27 28 30 15.5 10 25 11 1 44 26 17.5 21 13 9 37 16 22 20 2 3 42 466 120 69 182 267 308 352 37 154 90 230 333 382 431 537 471 125 73 275 314 358 188 109 174 472 416 264 78 147 399 223 352 92 89 448 11 19.5 16.5 14 18.5 16 16.5 21 40 51 22 67 28 53 43 54 60 33 82 25 21 7 24 69 59 51 18 6 520 57 78 24 8 31 317 1-28 four-core 204 A A AA 12 25 21 19 18 29' 20 15 16 11 12 14 13 48 41 119 482 405 346 22 14 19 44 104 251 165 395 1 twelve1 301 Horizonta loaded cable loaded Flat all allsingleloaded A A A A 2 124 sevencable cable, AfourIVertical spaced 17 three-phase touching 39 single cables a.c .. cable 3 three-phase loaded phase a.c. 1 two- - core nineteen1 1.0

a.c.

p.v.c.

Ambient temperaPire: 3O-C Sheath operating temperature: 70C 1

space

cable all

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.

..• ..•

Table Dol7 Mineral insulated cables bare and exposed to touch (see note 2) or having overall covering of P.V.C•

10

(copper conductors and sheath) (conte'd) Current-carrying capacity (Amperes): Reference Methods 12 and 13 (Free air) - Horizont - -cables loaded threecable 3 cores four-core 1 two20 213 259 353 309 400 446 497 110 142 173 26 34 45 37 49 62 84 -- 1or I all-9---cores

.

16 16.5 18 loaded A 19 37 40 496 30 32 22 16 22 30 1 cores seven56 59 44 89 223 466 40 92 101 11 14 308 loaded load loaded cores al 377 241 132 24 28 2 8 all 28 35 29 27 28 26 25 24 23 26 25 32 A 15.5 10 11 17 21 12 9nineteen20 27 30 23 18 17.5 14 21 21 core 1all 1 twelvefour-core cable cable cable 41 34 45 426 331 31 242 23 29 39 51 43 57 71 77 95 289 351 507 565 102 125 161 197 402 198 147 267 A A A A A 78 68 51 69 352 51 182 116 120 13 18 25 294 162 33 1 core 19.5 44 45,4A399 21 174 264 47 60 472 20 26 36 317 215 109 82 416 552 142 phase a.c.or Vertical 1cable, three core Touchin phase a.c. or cables ind.c. trefoil threespaced 1.0 1

.•

A

Ambient temperature: Sheath operating temperature:

phasea.c. a.c. 3 phase single-core

3 single-core cables threespaced

I

Note_"

i) For ~in_gle-c?~e_ ~~ble~~~"",s?..=:,-~s .~"O~

~

••

~_~~c::';~~ ~~~"'~~~~~dt~~..-..a~::~:::~~~~g~t:Per at both ends.

.

3O"C

7DC


TableB.28 Mineral insulated cables bare and exposed to touch or having an overall covering of p.v.c (copper conductors and sheath)

Voltagedrop (per ampere per meter) for single-phase operation sheath operating temperature: 70°C --

-z--x-z r 0.200 x0.145 0.160 0.25 0.185 0.165 0.175 0.49 0.91 0.29 0.180 0.64 0.170 0.41 0.34 0.195 1.65 1.65 1.20 1.65

0.62 0.37 1.20 0.190 0.89 0.46 0.25 0.30 1.65

.

2.6 2.6 10 4.2 2728 42 1"1 317 42 Multicore 4.2 10 mV Touching cables mV Two single-core cables,


EBCS-10 1995

119

-


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 --- r r r Three single-core cables 10.31 cable -V-0.56 x x-z0.21 0.21 0.28Spaced 0.140 0.26 0.26 0.39 0.54 0.155 0.58 41.600.1251.60 50.44 3m0.41 0.30 0.65 224 0.32 0.150 0.36 0.36 0.28 0.78 0.40 0.26 0.1650.1400.22 0.36 0.26 0.32 0.160 0.150 0.145 0.25 0.27 0.21 0.79 0.80 0.43 0.30 0.36 0.42 0.22 0.47 0.83 6.06.0 9.19.1 2.3 3.6 3636 14 2.3 3.6 6.0 9.1 14 24 36 2.3 3.6 14 1.05 1.45 0.165 0.170 1.45 1.05 1.05 1.45 1.05 1.45 0.32 0.25 0.24 1.10 1.50 1.10 1.45 0.200.29 0.82 0.29 0.29 0.87 0.53 mV 0.25 0.55 0.23 0.60Touching.Flat formation 0.33 0.220.46 0.40 Multicore 24 mV Trefoil, touching Conductor diameter apart

120

EBCS-10 1995

cables


Table B.29 Mineral insulated cables bare and neither exposed to touch nor in contact ""th comhustible materials (copper conductors Current-carrying capacity (Amperes): Reference Method 1 (Oipped Direct) 1.0

---- ---1 four-core cables a.c.inthreeflat loaded 544 312 35 41 2485 212 19 40 46 36 117 134 140 260 119 107 59 50 33 171 22 17.5 17.5 20 26 465 14 13 trefoil 1 twelve-core or 1in 334 572 230 2 4 68358 95 single core 18.5 21 A 32 53 16.5 27 383 47 2 21 359 435 410 44 4cables '22 24 30 492 12 15.5 280 67 187 154 103 28 90 cables loaded loaded phase 1 seven-core a.c. or 7A three-core 16.5 cores loaded' cable cable all all cores cores core cable all 251 22 A 70 28 38 51 31 cable, 1 nineteen-' three55 203 307 127 166 424 24 550 cable, phase singlea.c. 3 single-core 369 643 42 cores 3 cable single-core 3loaded cores, three-phase

1 cable, four-core phase all a.c.

and sheath) Ambient temperature: 30"C Sheath operating temperature: 105°C

formation,

10.5

\

ii) No correction factor for grouping need be applied. iii) Where a conductor operates at a temperature exceeding temperature.

7ffc it shall be ascertained that the equipment connected to the conductor is suitable for the conductor operating

Table B.29 Mineral insulated cables bare and neither exposed to touch nor in contact with combustible materials (copper conductors and sheath) (conte'd)

•....•

tv tv

Current-carrying capacity (Amperes): Reference Methods 12 and 13 (Free air) ----61 137 56 105 216 266 323 385 178 441 498 624 26 33 43 47 78 Touching a.c. core 1 1.0

.

Ambient temperature: 30"C Sheath operating temperature: 105'?C

1phase cable four-core cores all 441 629 500 35 46 85 87 56 70 64 63 51 64 146 150 43 71 617 385 26 50 40 28 38 37 19 18 12 11 16 530 24 30 73 120 A 96 115 54 112 For S1n21e-corecables, the sheaths 01 the CIrcUItare assumed to be connected tOQetler at both ends. 127 157 39 359 23 29 200 247 300 411 469 204 164 89 29 37 49 248 304 370 505 565 704 441 54 228 279 335 21 20 14 584 126 26 18 49 34 184 25 32 28 13 19 11 32 35 14 32 17 15 three-core Horizontal 1all trefoil loaded 1 core threefour-core cable cables twelveloaded threecores cable orsingle3..in 1 A A A A 97 2 22 43 16.5 1 core loaded all loaded all cores nineteen1 cores sevencores cable 54 cable, 41 76 A 24 31 137 179 333 400 460 220 60 33 45 phase spaced a.c. 3 single272 526 697 104 Vertical a.c 557 cable, phase two-core a.c. spaced single3 single-core cables three-phase

10

ii) iii)

No correction factor for grouping need be applied. Where a conductor operates at a temperature exceeding at.inp:: temporat.-ure. ope •...

7Cf'C.

it shall be asce:1:ained that the equipment connected to the conductor is suitable for the conductor

l


Table B.30 Mineral insulated cables, bare and neither exposed to touch nor in contact with combustible materials (copper conductors and sheath) Voltage drop (per ampere per metre) for single-phase operation Sheath Operating Temperature: 105°C

, -- 0.51 x0.145 x-z-1.85 r 0.26 z1.00 0.155 0.36 0.33 1.85 0.150 0.160 0.44 0.31 0.41 0.27 0.21 1.85 1.35 1.35 0.165 0.71 0.69 1.00 1.850.180 0.175 0.170 0.54 6 Conductor ~ i.

Touching 3.0 4.7 231 331 47 47 7.8 12 12 19 4.7 A 7.8 19 3.0 A Two single-core cables


Multicore cables

EBCS-10 1995

123


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

- zr-x xz r xrx

-76Trefoil touching 0.1800.1300.22 6.8 2.6 2 0.60 0.36 0.29 0.145 0.135 0.26 0.63 0.39 0.34 0.61 0.31 0.22 0.37 0.62 0.25 0.290.70 0.38 0.27 0.195 0.32 0.21 0.20 0.36 0.43 0.48 0.29 0.65 0.37 0.42 0.87 0.150 0.90 0.88 0.88 0.29 0.22 0.95 0.91 1.15 1.60 0.155 0.160 1.60 1.15 1.60 1.20 0.125 1.65 0.31 0.23 1.65 1.60 1.20 1.65 0.45 0.140 0.48 0.46 0.47 0.28 0.21 0.56 0.50 0.23 0.130 0.29 0.26 0.26 0.27 0.39 0.33 5 4 3 '4.1 27 16 4.1 40 10 2.6 6.8 10 16 40 27 6.8 2 40 1 mV mV Flat formation Touching 10 2.6 4.1 1.20 1.25 Three single-core cables cables mV 2.6 Spaced 10.30 cable Multicore diameter apart

r

124

EBCS-10 1995


Current-carrying

120

cross-

Table B.31 Single-core P.V.C.-insulated cables, non-a •.•••oured, "..jth or without sheath (aluminium conductors) capacity (Amperes):

-three3 or 4 threeand or d.c. flat cables,thre Reference Method 413 cables, 545 Reference Method 11 phase 1022 477 900 touching 771 a.c. e-phase -Reference -three(clipped direct) 1 Method 625 507 680 787 837 8956144 210 234 435 306 261 312 375 149 230 316 237 273 274 317 501 466 344 170 215 189 289 164 252 128 148 107 165 181 129 203 234 191 A 1293 1026 776 902 546 590 761 953 907 926 11 84 472 584 352 502 511 543 3Bspaced or 4a.c. 10 266 4 245 210 225 358 410 269 227 354 432 3364 299 226 204 123 150 159 12 444 433 469 384 407 324 394 298 240 283 277 301 134 104 163 132 11 172 133 169 185 161 256 206 538 194 186 118 142 293 462 626 679 669 722 71066 1073 1125 1229 823 709 956 820 405 726 582 629 886 591 999 cables threeor Trefoil d.c. or or d.c. d.c. threed.c. flat or or 3spaced 3Horizontal 2 cables Vertical and flat A a.c. flat4 2cables cables, singlephase a.c. phase singlesinglephase a.c. phase a.c. Reference Method tray, or cab3 I 12 (free air)(on ahorizontal perforated flat 3 cables trefoil flat trefoil and and 2 cables, singleReference Method 2 cables, 2 cables, touchingor single(enclosed conduit etc.) on phase a.c. a wall or inintrunking

Ambient temperature: 30°C Conductor operating temperature: 70°C vertical)

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

~ ~

Table B.32 Voltage drop (per ampere per meter)

,,,.

,

1 J I5

0.094 Reference Methods Reference Mllthods 12 {Indirect treflJi "1 fI' 11 ,nd{cippetl Zx fin tray$, ,nd tflUching} 11 tflUChing} z0.91 A z1.35 x0.21 zZXxx 0.26 Reference 3 mV mV ow 0.25 D.24 0.077 0.074 1.40 0.26 1.15 0.24 4mV 2 c,bIes . singfe-p/llse a.c. Methods D.26 0.77 0.39 0.155 0.70 0.77 0.155 0.34 0,48 0.31 0.26 D.29 0.37 0.79 0.52 0.145 0.30 0.35 0.67 0.170 0.59 0.61 0.45 D.25 0.92 1.40 0.64 0.110 0.24 1.35 2mV C8bJesd~. 0.22 D.22 0.071 0.155 0.24 0.155 0.170 0.082 0.077 0.068 0.075 D.29 0.060 0.066 0.086 0.23 0.089 0.135 0.165 0.094 Referenc, M,thod 12 D.28 0.42 0.21 0.67 0.53 0.26 0.34 0.24 0.91 0.61 0.49 1.05 0.170 0.195 0.23 0.55 0.45 0.36 0.125 1.55 0.190 0.135 030 0.110 0.140 0.24 0.21 0.61 0.53 0.49 0.30 0.28 0.26 0.40 0.165 1.05 1.55 0.91 0.42 0.67 0.130 0.32 0.29 0.30 D.27 0.71 0.58 0.51 0.145 0.74 0.160 0.61 0.27 0.40 0.35 0.44 0.1511 0.28 D.28 0.41 0.97 0.94 0.64 -'.,0 0.26 D.23 0.140 0.35 0.27 0.43 0.21 1.35 0.185 0.190 0.28 0.32 1.05 1.55 1.35 0.30 0.23 0.82 0.25 0.31 0.55 0.37 0.86 0.185 0.70 0.1811 0.175 0.42 D.24 D.26 0.511 0.52 0.36 0.27 0.74 0.26 0.40 0,47 0.46 0.96 0.22 0.165 0.29 0.23 0.69 0.55 0.160 0.30 1.60 0.25 0.37 0.23 0.22 D.23 0.22 0.81 0.51 0.32 1.60 0.42 1.10 D.22 0.1811 0.1511 "0.1811 0.190 0.1811 0.140 0.23 0.1511 0.120 0.77 0.099 0.190 1.55 1.05 0.61 0.49 0.39 0.30 7etc. 0.059 •0.195 0.28 0.066 .0.135 4ctmduit {enclosed in andIFIIt ..1.55 etc. inMethods If fin0.1511 , 3 3 " 4 c,bIes· 0.27 1.35 sp,c.!} Reference 0.100 0.94 Cflnduit in II' fiR ,0.105 ,nd 4,nd (fndostJd in Reference MiJtlllJds Reference MethlJd 121 wall {sp,c.!} 11 {Flat tflUchingJ

Conductor Operating Te~perature:70 tJuee.(Jhasea.e.

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

"C

Table B.33 Multicore P.V.C,-insulated cables, non-armoured (aluminium conductors) Current-carrying

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

capacity (Amperes):

n

207 237 135 155 176 245 210 280 330 285 212 227 259 248 305 351 160 197 184 Reference direct) Method 3 11 (on a -A -singleReference Method (enclosed in or d.c. 104 86 278 150 140 160 58 ·1 11381 threeor four108 131 118 210 116 139 173 157 170 195 183 98 4 cable, 44 54 41 73 71 53 65 3 A 6110 66 48 61 89 83 62 89559 A 7 125 111 117 135 92 96 90 .130 a.c. a.c. d.c. threecable, threecore core or cable four1a.c. two-core 103 cable,three1 two-core, phase phase three-phase phase three-phase phase a.c. a.c. or a.c. or cable, core singlecable, cable, singlesingle1 two-core Reference MethodMethod 4 Reference (enclosed in air) 1 (clipped trunking) Method Reference 13 (free cross- sectional

perforated cable tray), or

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


.

,

1 J I5

0.094 Reference MethlJds z1.05 In tny£. tlUelling) 12 {TntrefrJi Reference MethtJds "1 01 1111nt1 11 {tipped direct 1Int1 touching) II II 0.53 IZ0.135 r0.28 x0.37 A Z X zZD.21 X XX 0.64 X mV mV 1.35 0.26 0.77 1.05 0.36 0.77 0.40 D.28 0.26 0.35 0.15/1 0.40 0.79 0.31 D.24 0.86 0.185 0.61 0.5/1 0.37 1.10 0.61 0.42 0.49 0.51 1.15 D.29 0.51 0.49 1.55 0.190 0.27 0.26 0.26 0.180 0.24 0.099 2mVubles d.c. 0.67 0.34 0.91 0.53 0.61 0.39 1.55 0.55 0.70 030 0.53 0.61 0.165 1.05 0.30 0.91 1.55 0.67 0.34 0.58 0.61 D.29 0.71 0.74 0.160 0.44 0.97 0.37 0.41 0.94 "1.10 0.64 0.43 1.40 D.35 0.185 0.190 D.28 1.55 0.32 0.67 0.27 0.70 0.180 0.82 0.25 0.74 D.26 0.46 0.47 0.40 0.42 0.96 0.55 1.60 1.40 0.30 0.92 1.35 D.23 0.24 1.60 0.42 0.81 0.32 0.77 0.39 1.05 0.30 4mV 7 0.42 0.23 0.22 0.45 0.089 0.071 0.059 0.49 0.42 0.48 0.25 0.52 0.135 0.155 0.55 0.26 0.30 0.59 0.175 0.52 0.45 D.24 0.24 0.23 0.21 0.180 '0.28 0.170 0.165 0.082 0.155 0.068 0.094 0.077 0.075 0.29 0.060 0.066 0.077 0.074 0.086 mr 0.21 0.24 D.28 D.26 0.170 0.195 0.125 0.23 0.110 0.140 0.130 0.24 0.155 0.21 0.32 0.29 0.30 D.27 0.31 D.26 D.28 0.145 0.23 0.145 0.140 0.27 0.21 0.30 0.35 0.170 0.36 0.23 0.165 0.22 0.29 0.25 0.160 D.25 0.26 0.22 0.22 D.22 0.21 0.15/1 /0.23 0.195 0.180 0.140 0.110 0.15/1 0.120 0.190 0.190 1.35 1.35 1.35 0.69 mV 0.066 .0.135 0.15/1 Reference MethtJd 12 0.155 4ClJndtit {endtJstJdin etcy inMethtJds IJf on II 3 and D.27 IFIIIt SPIIC.!) 0.100 .;1.55 Reference 0.94 conduit etcy in bl In II0.105 1Int14 Reference (EndtJSIJd in MethIJd Reference Methods (spac.!) IInd 11 (Flat tluclling)121

Conductor Operating Te~perature:70 2 cilbies . single-p/lIISBII.C. Reference MethtJds 3 3 II 4 cilbies . t!IrrJe.pMSBII.t.

WIIIJ

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

"C

Table B.33 Multicore P.V.C,-insulated cables, non-armoured (aluminium conductors) Current-carrying

n

210 248 330 237 285 381 135 155 176 259 305 351 184 212 245 280 227 160 197 Reference direct) Method 3 11 (on a -core Reference Method {enclosed in -singleor d.c. 58 78 150 11207 threeor core 44 54 41 71 53 65 66 48 61 83 62 59 108 131 139 157 116 170 195 183 160 98 4 cable, 2118 56140 9a.c. 104 125 86 117 135 92 90 96 .130 a.c. d.c. threethree1a.c. two-core or fourcable, cable 73 89 210 173 111 1 83110 03 7a.c. A A A cable, two-core, threecore cable, phase phase three-phase phase three-phase a.c. a.c. orfouror phase cable, cable, singlesinglesingle1 two-core Reference Method 4 {enclosed in

cross- sectional

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

capacity (Amperes):

trunking) Reference Method Reference 13 (free Method air) 1 {clipped

perforated cable tray), or

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

•

r ELECTRICAL INSTALLATION OF BUILDINGS


Conductor operating temperature: 70°C -

120

0.53 0.42 0.34 0.26 x0.25 z0.175 r0.170 x2.9 Two-core Conductor2.50.150 4.5 2.9 1.80 0.90 1.35 0.67 0.170 0.165 0.160 0.68 01.80 1.35 0.92 2.1 0.79 1.55 1.05 .145 .150 .140 2.5 1.55 1.05 0.77 2.1 2.9 1.55 0.77 1.05 2.1 34.5 three-phase 0.130 0.55 0.44 0.37 0.135 0.30 mV mV 20.21 43.9 cable d.c. mV Three-or four-core cable, phase a.c.singeTwo-core cable a.c. cross-

1

128

I

EBCS-10 1995


Table B.35 Single-core armoured P.V.C.-Insulated cable, Non-magnetic armour. (aluminum conductors) Ambient temperature: 30"C Conductor operating temperature : 70"C

Current-carrying capacity (Amperes):

cross

cables Reference 11 a.c. flat and 2 2221 cables single-phase a.c. Method 143 819 452 393 518 586 728 183 255 294 334 893 singlea perforated cable phase a.c. cables Horizontal spaced phase a.c. (onflat 596 642 715 769 802 618 656 828 859 168 303 200 178 497 133 141 374 372 214 245 205 233 246 238 267 282 275 319 315 194 213 202 518 551 613 638 559 152 131 155 169 157 167 413 415 443 452 472 437 234 255 247 261 270 272 293 303 285 310 312 335 349 323 352 379 382 400 543 168 259 299 340 389 196 1171 1360 706 808 952 880 868 866 1317 774 770 822 10 8342550 12 11 6520 ,2Reference 405 501 534 568 427 498 430 475 616 604 655 474 505 545 589 666 707 986 770 696 724 A A 975658 452 479 202 692 212 159 354 832 1133 726 902 938 756 457 236 288 333 371 583 742 629 523 or d.c. trefoil -651 3 Vertical cables Horizontal A Vertical flat singleflats paced touching Horizontal 2 3 cables or flat d.c. flatspaced three-phase spaced -t1)uching Method 14 cables, 3spaced or 4 cables and three-phase

a.c.Reference Method 12 (free air)

~

IV

\0

Note:

Where the conductor is to be protected

by

a semi-enclosedfuse, see A.6.2 of the Preface to this Annex.

Table B.36 Voltage drop (per ampere per metre) Conductor operating temperature: 70°C Reference 2 cables d.c.and 12 1,11 (In rrrr 0.190 x0.60 z0.23 x0.23 z0.22 xzz 3 0.160 0.097 0.075 0.26 0.190 0.150 0.24 Reference Method 1.55 0.21 0.170 0.155 0.21 0.190 0.170 0.15 0.120 0.060 0.30 0.38 0.32 0.22 0.26 0.28 0.35 0.40 0.29 0.38 0.44 0.26 0.51 0.30 0.58 0.170 0.28 0.39 0.160 0.165 0.28 0.39 0.47 0.24 0.50 0.41 0.39 0.49 0.30 0.54 0.62 0.61 0.81 0.68 0.70 0.78 0.77 2mVrY)V 7mV 56Reference 4Methods 1.35 0.93 0.92 1.35 0.31 0.195 0.33 1.35 1.10 0.190 0.93 1.35 0.22 0.26 1.55 1.05 1.05 0.185 0.26 0.27 0.094 0.180 0.115 0.100 0.195 0.185 0.145 0.175 0.140 0.165 0.32 0.24 0.200 0.175 0.31 0.22 0.150 0.23 0.145 0.20 0.170 0.160 0.21 0.24 0.180 0.185 0.25 0.160 0.200 0.165 0.135 0.115 0.110 0.32 0.29 0.54 0.28 0.33 0.42 0.50 0.46 0.195 0.24 0.155 0.37 0.45 0.53 0.24 0.34 0.27 0.44 0.34 0.185 0.22 0.45 0.27 0.52 0.25 0.35 0.36 0.27 0.32 0.18 0.190 0.195 0.20 0.180 0.22 0.66 0.60 0.57 0.65 0.62 0.68 0.71 0.180 0.57 0.25 0.21 mV 0.73 0.70 0.81 0.75 0.80 0.86 0.21 0.95 1.30 1.55 1.05 0.96 1.55 1.00 0.130 Methods 0.3~ 2 cables, 3 single-phase or 4 cables, a.c. three-phase a.c. 1 and touching) 11 (Flat 12 (Spacedt) Reference Methods Method1 and 11 (Touching) 12Reference (Flat spacedt)

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

:


Table B.37 Multicore armoured P.V.C.-insulated cables (aluminium Current-carrying

Conductor

conductors)

capacity (Amperes):

Ambient temperature: 30"C Conductor operating temperature:70"C 94-or Reference Method 13 (free air) 113 115 175 Reference Method 11 or99 d.c. 202 232 360 3 216 250 342 Reference Method 1 1A two-core 287 cable, 265 312 single-phase (clipped a.c. (on direct) a perforated cable tray) 131 68 61 2three4 599 143 199 139119 211186 1cable, or A 3 58 94 89 71 80 151 A 76 four-core 1 threefourcore threecable, A phase a.c. phase a.c. or three-

ingle-

Note:

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

131


Table B.38 Voltage drop (per ampere per metre) Conductor operating temperature: 0.53 0.42 0.26 0.21 -Two-core r 0.90 x2.10 z1.55 z1.80 Two-core cable Conductor 0.31 0.135 6.135 0.55 4.5 3.9 2.50.150 1.35 1.80 0.67 0.150 0.140 0.170 0.165 0.160 0.175 0.170 2.90 0.79 1.05 0.92 1.35 2.90 2.10 1.55 0.77 0.77 1.55 1.05 2.9 2.1 0.44 2mV 3 three-phase 4 cableor single0.130 0.30 0.25 mV mV 0.145 0.68 2.5 1.05 d.c.4.5 0.37 Threefour-core cable, phase a.c. a.c. ~ cross-

70°C

1

132

EBCS-10 1995


._••~

•..••.••~~

__ i

t
(alUID.inium con.duc1.ors)

-=-b.~,.

_CJl

•• -

CJl••••

~

Ambient temperature: Conductor operating temperature:

Current-carrying capacity (Amperes): -a.c. Reference Method 3 or 112 (free air) cables, I 410 three-phase 1001 1176 1333 353 469 564 656 765 671 Horizontal direct) -3trefoil -A-a.c. Reference -flat Method Reference Method a.c. flat and 471 344 561 367 4 3 7 12 5 6 11 2phase 1056 649 300 256 1151 1307 395 470 515 343 406 446 509 507 544 652 541 742 796 665 726 692 636 1143 1072 1440 1106 1643 1217 1355 366 911 951 979 990 266 336 242 200 .149. 171 217 253 215 142 273 296 210 159 226 157 113 265 261 206 244 251 351 140 197 191 125 156 220 253 or 4 4 Reference Method 11 or d.c. 10 9 1025 1216 376 469 566 679 743 1191 396 430 314 346 436 706 594 626 927 766 903 791 1249 1341 1550 A cables a.c. 231 261 234 332 271 211 306 367 326 165 169 179 160 166 or 323 orcables, 4(clipped a.c. a.c. or a.c. d.c. flat flat or4or and or d.c. and33etc.) & Vertical flat a.c. trefoil, singleor d.c., or 611 4cables, 2three-phase 2 cables, cables, three-phase cables, single2 cables, three-phase touching phase phase or a.c. spaced 3...ables three-ph¥e touching three-phase three-phase singl/:!singlesingletouching Reference Method 3on, a a.c. ora.c. d.c. (on Trefoil 2 cables, horizontal vertical (enclosed conduit phase wall a perforated or or inintrunking cabletray etc.)

Note:

1.

ii

3O"C

9{fC

flats paced

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 7fJ'C, it shall be ascertained that the equipment connected to the conductor is suittable for the conductor operating temperature

Table 8.40 Voltage drop (per ampere per meter)

r

~. 0.21 0.135 0.165 0.150 0.27 0.1700.165 0.155 0.17 0.23 (enclosed in 0.155 -1.65 2 -0.1400.165 -0.32 x1.72 r r-r-0.079 z0.98 x-zxx1.70 (enclosed in r0.070 0.170 0.150 0.41 0.36 0.31 0.28 028 0.22 025 0.28 0.32 0.28 0.36 0.26 0.30 0.28 0.185 0.160 0.61 0.155 1.00 1.04 1.46 1.48 0.97 0.45 0.36 0.75 0.48 0.26 0.71 0.57 0.45 0.165 0.24 1.12 0.82 0.65 0.43 0:36 0.91 0.79 0.64 0.54 0.53 0.45 1.21 1.15 0.57 0.36 0.47 0.39 0.73 0.59 0.86 0.68 0.54 1.08 1.14 0.84 1.44 1.45 0.52 1.65 1.12 0.71 0.30 0.135 0.145 0.27 0.26 0.22 0.165 0.120 0.150 0.07 022 0.076 0.23 0.31 45 0.22 0.25 0.110 0.145 0.35 022 0.30 0.38 0.34 0.27 0.30 0.34 0.41 0.37 0.71 0.29 0.180 0.25 0.175 0.24 0.50 0.43 0.57 0.38 0.32 0.94 0.23 0.74 0~70 0.61 0.58 0.49 1.68 0.97 0.45 1.17 0.45 .cables 0.64 0.54 0.67 0.55 0.46 0.57 0.65 0.42 0.28 0.120 3.24 0.150 0.31 0.28 0.32 0.23 0.140 0.135 0.20 0.120 0.22 0.1400.160 0.25 0.21 0.26 0.29 0.24 0.30 0.087 0.082 0.082 0.092 0.1350.160 0.18 0.23 0.180 0.25 0.180 0.20 0.34 0.145 0.180 0.23 0.22 d.c. 2.0.33 mV mV e789touching) 0.063 0.28 0.29 0.070 0.21 0.27 0.095 0.100 0.100 0.21 0.1150.160 0.1350.170 0.23 0.19 Methods 1 and 11 0.22 0.190 1.44 0.52 0.78 1.66 0.62 Refer~nce Reference Methods Reference 111 and Methods 4 0.59 0.21 , Methods 1. conduit, etc3~orand on mV 0.30 0.• 473 Reference Method and 12 (in trefoil) (flat on touching) trays, a wall) 11 (clipped Method . 3 or 4 cablesReference - three-phase a.c. 1.13 Reference 0.32 0.26 0.53 0.42 0.82 0.130 0.080 0.160 0.105 Methods 3orand and 4direct 2 cables - single-phase a.c. 12 (flat 12 (Spacedt) spacedt) -'

0.20 0.65 0.064

t

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

Conductor operating temperature: WOe

Tabl •••B~

ftIlI••• tI_·~8

1•••••••• (aluminium conductors)

Current-carryingcapacity(Amperes):

cross

Note:

273 272 440 180 theeor four-incable 206 233 323 216 245 240 283 318 382 364 1313 two-core 263 304 409 471 -1-three347 .Reference (enclosed core cable, three.-phase a.c. --corecable, conduit on Method a wall or3 ceiling, tray), or Reference . perforated d.c. 175 145 115 78 60 Reference Method 11 (on a 2 3 210 211 175 131 198 156 188 211 257 104 136 154 124 138 115 87 96 94 71 112 103 90 6157 755 76 64 72 5 4 241 174 227 187 164 146 A 89135 101 126 108 97 84 1 cable,singlefour-core s.c. d.c. A A 977 120 1 two-core or d.c. A 1 two-core cable, threephase a.c. four phase a.c. cable, 1 phase three-pbase two-core singlea.c. oror cable,singlecable, singleReference Method 4 (encloseddirect) 1cable, threeor four-core phase a.c. threeReference Method 1 (clipped

• non-••••••• ou..-

Ambient temperature: 30"C Conductor operating temperature: 9O"C Method 13 (free air)

i) Where the conductor is to be protected by a semi-enclosed fuse, see A.62 of th" Preface to this Annex .. ii) 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.

ELECIAICAlINSTALLATION

OF BUILDINGS

Table B.42 Voltage drop (per ampere per metre) Conductor operating temperature: 90°C --0.56 0.45 0.28 0.37 0.23 -- d.c. x0.165 r0.71 x3.10 z0.82 Two-core cable z1.95 Conductor 0.1500.84 0.72 1.90 0.96 1.400.135 2.7 0.160 0.155 0.160 0.140 0.135 2.7 0.97 1.45 2.20 3.10 1.15 1.65 1.10 1.60 3.1 2.2 4.8 4.2 2mV 4 cable 0.125 0.130 0.31 0.47 0.39 0.82 0.26 0.140 2.20 1.65 1.10 mV a.c. mV 34.8 0.58 Two-core single- a.c. phase three-phase

Three or four-core cable,

1

136

EBCS-10 1995


Table D.43 Single-core cables having thermosetting insulation, non-magnetic armour (aluminium Current~carrying

conductors)

capacity (Amperes): Conductor

Horizontal flat spaced Reference Method 1163 276 228 179 419 368 320 836 934 747 655 1236 568 494 1076 1250 1121 1094 1014 1187 212 786 880 706 988 764 688 597 468 400 444 352 390 308 340 267 307 222 176 192 199 872 909 757 1036 801 780 950 989 824 897 835 642 790 825 685 714 717 765 906 1435 1488 1052 573 704 735 608 625 649 639 1658 1715 1141 508 595 626 666 701 624 654 536 521 443 523 554 572 605 549 378 467 490 391 477 480 333 337 394 411 441 409 429 291 343 372 384 294 332 310 328 252 296 209 207 244 253 275 254 269 162 165 942 576 511 197 216 838 890 903 990 970 980 3 3 or or flat 44single-phase 1056 1118 465 A 215 911 1043 540 447 424 292 357 358 270 812 324 192 832 and 22d.c., cables cables cables, 2 Method cables d.c. Vertical Vertical 3911 Horizontal trefoil Vertical cables flat flat a 120~ or d.c., a.c., Horizontal touching cables, Reference perforated cable tray) 11 (on three-phase phase a.c. flat spaced spaced single 3 or 41 Ii.C. cables, three-phase or phase flat single2 a.c. Acables,

a.c.

Ambient operating

temperature: temperature:

Reference method 12 (free air)

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 7rflC, it shall be ascertained that the equipment connected to the conductor is suitable for the

conductor operating temperature.

30°C 900C

/

l.H

00

Table B.44 Voltage drop (per ampere per meter) Conductor Reference Methods 1, z0.34 x0.25 z1.10 x.31 Reference 1(Flat rr r 0.29 - Methods ,11 and (In(Flat trefoil 0.27 0.165 0.160 0.22 0.175 0.140 0.24 0.105 0.21 0.150 0.160 0.175 0.21 0.135 0.175 0.31 0.24 0.20 0.22 0.140 0.29 0.29 0.32 0.26 0.160 0.46 0.40 0.41 0.32 0.35 0.175 0.23 0.160 0.39 0.165 0.29 0.34 .29 0.23 0.160 0.32 0.26 0.21 0.40 1.40 0.71 0.76 0.30 0.165 0.90 0.175 0.76 0.26 0.190 0.24 0.20 0.47 0.41 0.74 1.40 1.60 0.43 1.60 2 Cables 0.49 0.60 0.46 0.99 0.97 0.60 0.160 0.26 0.170 1.05 0.21 0.54 0.64 0.96 0.49 0.60 0.33 0.66 0.53 1.10 0.52 0.66 0.20 0.190 0.25 0.170 0.195 0.135 0.093 0.140 0.26 0.120 0.105 0.080 0.064 0.24 0.22 0.190 0.120 0.26 0.145 0.33 0.170 0.195 0.21 0.160 0.105 0.130 0.39 0.35 0.33 0.25 0.24 0.37 0.30 0.195 0.23 .0.160 0.25 0.36 0.45 0.34 0.25 0.22 0.155 0.34 0.27 0.26 0.34 0.27 0.185 0.47 0.44 1.60 0.65 1.35 0.46 0.74 0.54 0.27 1.60 1.40 0.63 0.22 0.32 0.63 .30 0.62 0.42 mV mV 0.63 0.15 0.96 0.69 0.57 1.10 0.52 0.56 0.69 0.29 0.70 0.74 1.15 0.62 1.00 0.25 0.30 0 Reference Method Reference Method 1212 0.22 0.20 0.165 0.36 0.53 mV mV 0.57 0.195 Reference Methods 1 - single-phase mV 0,20 and12 11 (Spaced1) andspacedt) 11touching) (Touching) 2d.c. cables

oss-

t

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

a.c.

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

operating

temperature:

9(fC


Table B.45 Multicore armoured cables having thermosetting insulation (aluminium

Current-carrying

conductor)

capacity (Amperes):

.

Conductor

Ambient temperature: operating temperature:

30°C 900C

two-core cable,a.c. (free 11 air)(on a perforated 305 418 single-phase 249 264 284 328 386 356 488 Reference Method 1 (clipped1 threedirect) or four-Reference Method 185 53174 242 201 159 132 1'08 112 211 138 254 137 145 113 120 214 224 98 21-A-441 4166 82 85 71 A A 1-- threeor four 74 92 core cable, three-phase a.c. cable tray) or Reference Method 13 single-phase 1 two-core a.c. cable corephase cable threea.c.

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 7fYC, it shall be ascertained that the equipment connected to the conductor is suitable for the conductor operating temperature.


EBCS-10 1995

139


Table B.46 Voltage drop (per ampere per metre)

.

Conductor operating temperature:

90°C

-----zx Two-core 0.45 0.23 0.37 0.28 r 0.56 Conduct 0.96 0.71 1.40 0.135 0.155 0.130 0.135 0.72 1.10 0.97 1.65 0.82 1.65 1.15 0.58 014.8 .10 .60 0.47 0.39 0.26 1.90 20.130 0.140 ..7 3.1 2.2 0.165 0.160 3.10 2.20 2.72.2 3.1 0.125 0.31 0.150 1.45 0.84 2.82 34.8 cable 44.2 1.95 mV cable d.c. mV 0.160 mV Three or four-core cable, Two-core phase three-phase a.c. singlea.c. or cross-

1

140

EBCS-10 1995


SECTION

5

EQUIPMENT

5.1

SCOPE

(1) This. Section covers services,

service equjpment,

and metering

equipment

and their

installation requirements for systems operating at 1000. OV 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) C22.1:1992

Canadian Electrical Code Part 1, Safety Standard for Electrical Installations, Sixteenth Edition

(b) NFP A 70/NEC: 1986 National Fire Protection Association/ AmericanNational Electrical ~ Code, 1987 Edition (c) IEE:1970

The Institute Electrical

of Electrical

Requirements

Engineers,

Regulations

for the

of Buildings,

Fourteenth

Edition

Incorporating Amendments

5.3

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

the supply conductors/cable that extend from the street main or from transformers to the service equipment of the consumer's installation.

141

EBCS-10 1995



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-tntrance 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 in$tallations 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

GENERALREQUIREMENTS

5.4.1

Number of ServicesPermitted

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

i)

the load requirements are in excess of 3000.0A at a voltage supply of 600.0V· or

ii)

less; _---/~ the load requirements of a single-phase installation are greater than that normally supplied through one service.

(c) For fire pumps wher~ 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 Marking (I) Where more than one service is permitted or provided, a pennanent 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. /

. 143

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 they will 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


5.5.1.3

Available short-circuit current

(1) Service equipment shall be suitable for the short-circuit current available at its supply tenninal.

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

General

(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

EBCS-10 1995



(c) means of earth-leakage protection (if necessary), Where the Supply Authority provides switchgear and pennits part of it to be used by the consumer, the consumer need not then duplicate that part.

Note:

5.5.2.2

Means of 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.

/

/

Overcurrent protection

5.5.2.3

(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 circuitbreaker; 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.

oJ

5.5.2.4

Earth-leakage protec#on

(1) Means for earth-leakage protection with Clause 9.4.2, Section 9.

shall be provid~d for service equipment in accordance

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


Sequence of control

5.5.2.5

(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).

~ ~:~:~~n~lu~in.~p~ue.::e~t'l~~!:"~I= owltchaut ••.• Included.)

f~

lObi

IIII

::d t~c.ica~~-::~

F•. ' Service rUle .nd ncutrallink. If .ny. Wh .upply. W.tt-hour meter and/or time .witch where requlrccl for ofl"-pcaklatifl" S Consumer'. linked .wltch. F•.2 Consumer'. main fu~ CB Consumer'. Iinlcedextas-currcnt circuit-bRoker with or without earthDb ~~~~P,'distribution board;

Figure 5.1 SeqJlence of control Note:

The consumer:s linked switch and the consumer's main fuse may be combined in a switch and fuse unit

5.5.2.6

Detached building

.. (1) Where a 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

,r

building. 5.5.2.7

Capacity of protective gear

(1) Every means of overcurrent protection shall be suitable for the maximum short-circuit current attainable or available. 5.5.2.8

V

Discrimination

(1) The characteristics

and settings of overcurrent protective gear, including fuses, and the

arrangement of the installajion shall be such that discrimination overcurrent protective gear is ensured.

147

EBCS-10 1995

in the operation

of the



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)

The installation is in accordance with Section 8;

ii)

Rigid conduit is used for mechanical protection where portions are exposed to injury; and

Hi)

5.6.1.2

The cable ~ without splice or joint from a point of connection at the supply service to the consumer's service equipment in the building.

Conduit to drain

(1) Consumer's service conduit entering a building underground shall be suitably drained.

5.6.1.3

Conduitseal

.(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} Other type' of rigid conduit, (b) Busway (c) Flexible metal conduit, the conductors being lead-sheathed cable (d) Mineral-insulated

cable other than the lightweight type

(e) Aluminium sheathed cable


EBCS-10 1995

148


(f) Any other suitable type cable (g) Service entrance cable, provided that: i) ii)

it is protected by an acceptable means if within 2.0m of the ground; the voltage does not exceed 230.0V to earth;

iii) it is supported at intervals not more than 1.0m; and iv) it is mounted on insulating supports which hold it not less than 500.Omm from a conducting surface, if adjacent to such a surface. Bare overhead supply conductors running on the outside walls of a building may be run as exposed wiring using types of conductor suitable fdr exposure to the weather . (2)

.(3) The length of consumer's service conductors beyond the service head shall ~e adequate. to enableconnection 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 condqctors 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:

Note:-

149

i)

200.0A for a meter mounting device, or'

ii)

600.0A for transformer rated meter mounting device located outdoors.

Transfonnerrated meter mounting device means a meter mounting device with current transfonners and with or without test sw.itches mounted in the same enclosure~

EBCS-10 1995


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

NORMATIVEREFERENCES

(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

National Electrical Code Handbook Based on the 1981 (NEC), Seventeenth Edition.

6.3

DEFINITIONS

(1) For the purpose of this Section, the followingdefinitions defined in Section 1.

demand factor

shall apply in addition to the terms

it is the ratio of the maximum demand of a system or part ora system, to the total connected load on the system, to the maximum demand of the whole consideration.

diversity factor

system,or

part

of a system,

under

the ratio of the sum of the individual maximum demands of the various subdivisions of a system, or part of a system, to t~e maximum demand of the whole system, or part of a system, under 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.


EBCS-10 1995

150

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 230.0Y or 380.0Y as applicable.

6.4.2 Yoltage 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 of 'the 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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(a) a basic load of 2500.0W for the first 70.0m2 of living area; plus (b) an additional 1000.OW for each 70.0m2 or portion thereof in excess of 70.0m2; 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 feed,er 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 45.0m2 of living area; plus (b) an additional 1500.0W for the second 45.0m2 or portion thereof; plus (c) an additional 1000.0W for each 'additional 90.0m2 or portion thereof in excess of the initial 90.0m2; 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

(t) any electric water heaters with a demand of 100% (2) The minimum ampacity of service or feeder cond~tors 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) Exciuding any air-conditioning loads, the load shall be considered to l;?e: i)

100% of the calculated load in the unit having the heaviest load; plus

ii)

65% of the sum of the calculated loads in the next 2 units having the same or next

iii)

smaller load to those specified in (i) above; plus 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

v)

smaller loads to those specified in (i) above; plus 10% of the sum of the calculated loads in the remaining units;


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SECTION 6: CIRG.UIT LOADING AND DEMAND FACTOR

(b) If air-conditioning is used, the amount by which the sum of all the air-conditioning loads exceeds 1500.0V A shall be added, with a demand factor of 100%, to the load determined in accordance with (a) above. (c) In addition, any lighting, heating, and power loads not located in dwelling units shall be added with a demand factor of 75%. The living area designated in Clause 6.5.1 and 6.5.2 shall be determined from the outside dimensions of the

Note:

group floor of the dwelling plus 75% of the basement area based on the inside dimensions, plus any area which might normally be used for living purposes on the upper floors.

6.5.3 Schools (l) 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) 10.0W/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 a building with an area upto and including 900.0m2 based on the outside dimensions. (b) For a building with an area exceeding 900.0m2 based 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 sum of:

V

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 900.0m2•

6.5.4

Hospitals

(1) The minimum ampacity of service or feeder conductors shall be based on the following: (a) a basic load of 20.0W/m2 of the area of the',building based on the outside dimensions; plus (b) 100.0W/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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••


(2) Demand factors may be applied as follows: (a) 80% for a building with an area upto and including 900.0m2 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-persquare-meter rating aDd 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 900.0m2•

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/m2 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 900.0m2 based on the outside dimensions; b) For a building with an area exceeding 900.0m2 based on the outside dimensions, the balance of the load may be divided by the number of square meters to obtain a load-persquare 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 900.0m2•


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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.QkW; 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 Mitadn 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 (1) 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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Table 6.1 Demand factor for service and feeders and watts per square meter for various types of occupancy

conductor

Feeders 100 90 100 80 70 80 100 70-90 qO 70 75 95 Service

50 15 10 20 5per m2 25 1Q Watts30

Demand factor

[%]

-.

Table 6.2 Feeder demand factors for lifts

0.95 0.90 1.00 100.73 0.79 0.85 0.77 0.82 orDemand 6987Demand more 0.72 0.75 Number of factors lifts on Number of lifts on (OF) a single feeder (OF)

Note:

Demand factors (DF) are based on 50% duty (i.e, half-time load, half-time no load).


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SECTION

7

EARTHING, BONDING, AND LIGHTNING PROTECTION

PART I - EARTHING AND BONDING 7.1

SCOPE

(1) Part I of this Section covers the prote;:ctionof electrical installation by earthing and bonding. (2) This part also covers provisions for insulating and guarding as suitable alternatives to earthing where permi~d 7.2

by this Code.


(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 701NEC:1987

An American National Electrical Code.

(c) IEE:1970

The Institute of Electrical Engineers, Regulations

for the

Electrical Equipment of Buildings, Incorporating Amendments.

Edition,

157

EBCS-10 1995

Fourteenth



7.3

SYSTEM AND CIRCUITS EARTHING

7.3.1

'Direct Current Systems

(1) A two~wire direct-current system suppiying 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 all3-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 if:

systems shall be earthed

a) by so doing, their maximum voltage-to-earth does not exceed 230.0Y; or b) the system incorporates a neutral conductor. (2) Wiring ,.. systems supplied by an unearthed supply shall be equipped with a suitable earth

(

Idetection 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) Wliere supplied by transformers that are energized from: i) systems of more than 230.0Y-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, (5) Where the transformers

the secondary circuits of the transformer shall be earthed.

are on switchboards,

the secondary circuits shall be earthed

irrespective of the voltage of the circuits.


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,.

SECTION 7:' EARTHING, .. BONDING AND LIGHTENING PROTECTION

7.4

LOCATION OF SYSTEM EARTHING CONNECTIONS

7.4.1

D.C. Systems

(1) D.C. systems to be e~hed

shall have the earthing connection made at one or more supply

stations; but not at individual services nor elsewhere on interior wiring.

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) The 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'toany

earthed circuit conductor on the load 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 relevant Clauses of Section 4 shall be met.

of the

7.4.3 Isolated Systems (1) 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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ELECTRICAL INSTALLATION OF BUilDINGS

a) The earthing conductor shall not be smaller than that specified in Table 7.1. b) If two or more systems are employed, a common system earthing conductor shall be installed unless separate earthing is supplied for each such system, in which case the earthing for 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

~lectrical equipment in or on the building or structure shall be pennitted 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, 3-wire, the identified neutral conductor; c) Multi-phase conductor;

systems having one wire common to all phases, the identified neutral

'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

(1) Where wiring systems, circuits, electrical equipment, cable annour, 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 connecti9ns 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 .

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ETHIOPIAN BUilDING CODE STANDARD

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160

SECTION 7: EARTHING, BONDING AND LIGHTENING PROTeCTION

c)· Interrupt the continuity of the conductors between the earthing connections. d) Take other suitable remedial 'action 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

(1) Atl non-current-carrying

Metal Parts ..

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 earthleakage current), it shall be 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,

7.S.~ Exposed Non-Current-Carrying (1) Exposed non-current-carrying

'''r name-plates isolated by isolating material. Metal Parts of Equipment

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.S.3 Non-Metallic Wiring Systems (1) Where nonmetallic wiring sY$tems are used: a) an earth connection shall be provided at all outlets; and b) metal boxes shall be earthed.

'.S.4

Non-Electrical Services

(1) Metal parts of water supply services and gas services which may become energized shall be bonded to earth.

161

EBCS-10 1995



(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 location 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 riot 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. _ Hi) Connection to the pipes of the services shall be made by means of a clamp.


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SECTION 7: EARTHING, BONDING AND LIGHTENING PROTECTION

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 ~

6670 of bonding 1.0t 16 50 50 50' 70 Nominal cross-sectional 2.5 1 6 6 2.5t mm2 1.0t mm2 area coductor are. Nominal of earthing cross-sectional conductor

mm2 j

t

2.Smm2

163

for bonding metal work of other services at points of entry to premises.

EBCS-10 1995


t


7.5.5

Extraneous Fixed Metalwork

(1) 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 extraneousfixed metalworkrequiredto be bondedand earthedin these circumstancesincludesthe following: i) Baths and exposedmetal pipes,sinksandtanks,in the absenceof metal-to-metaljoints of negligible electricalresistances. ii) Wherepracticable,accessiblestructuralsteelwork. Hi) Frameworkof mobile equipment,such as cranes and lifts, on which an electrical apparatusis mounted.

7.6

METHOD OF EARTHING

7.6.1

Effective Earthing

(1) 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

(1) 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

(1) 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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SECTION 7: EARTHING, BONDING AND LIGHTENING PR01ECTION

7.6.4

Underground Service

(I) Where an underground service cable is served from a continuous underground metal sheathed cablesystem 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 thebuilding if it is insulated from the interior conduit or piping. (2) Where a metal-sheathed service cable served from a continuous underground metal sheathed cablesystem 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 fromthe 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

(I) Fixed equipment shall be bonded to earth in one of the following ways: a) An effective metallic connection to earthed metal raceways, 4metal sheath, or cable ' aiIDOUrexcept: i)

Armour as specified in Clauses in '(2) and (3) below; and/or

ii)

sheath of mineral-insulated and/or

cable when of stainless steel as specified in (4) below;

iii) where the raceway or cables are run underground, in locations subject to corrosion. b) A bon,ding 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.

165

EBCS-10 1995



(2) The armour of armoured cables incorporating a bonding conductor shali not be considered as fulfilling the requirements of a bonding conductor for the purpose of this ~lause, and the bonding conductor provided in these cables shall comply with (1b) 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

7.7.

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 (1b) or (1d) above.

7.7

(1)

con

ear

BONDING METHODS

7.7

7.7.1

Clean Surface

(1) (I) Where a non-conductive protective coating such as paint or enamel ii used on the equipment,

as~

conduit, couplings or fittings, such coating shall be removed from threads and other contact surfaces in order to ensure a good electriq~1 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:

7.

a) Service raceways or service armour or sheaths. b) All service equipment enclosures containing service entrance conductors including meter

(1

b:

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

n

Means of Assuring Continuity at Service Equipment

i

(1) 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


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 (1) Where service cable has an un insulated earthed service conductor in continuous electrical contactwith its metal armour or tape, the metal covering shall be c,?nsidered to be adequately earthed.

7.7.5 Bonding at Other-Than-Service Equipment (1) The electrical continuity of metal raceway, metal sheathed, or armoured cable shall be assuredby 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; bY 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 madeup in sections shall contain an earthing conductor to which each section shall be bonded.

7.7.7 Bonding Jumperst (l) Bonding jumpers shall satisfy the following:

A bonding jumper is a reliable conductor to assure the required electrical conductivity between metal parts required to be electrically connected.

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,.


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 be less than 19.0mm in width and not less than.:

metal parts; shall not

i) l.4mm in thickness if of steel; or ii) 1.2mm in thickness if of aluminium or copper.

7.8

EARTHING ELECTRODES

7.8.1

General

(1) 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 2S0.0mm below the normal permanent moisture level; and c) the underground building served.

portion extends not less than 3.0m beyond the extremities

of the

7.8.2.2 Independent metal water pipes (1) Where a conductive independent metal water piping system is used as earthing electrode, it shall be placed underground not less than 2S0.0mm 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


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 .5mm in thickness if

i

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

Ampacity of largest associated

conductor

50 35 70 95 25 [(mm2] Size of copper conductor

160 or less

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EBCS-10 1995



, 7.8.3.2

Rod electrode

(1) A rod electrode shall: a) be not less than 16.0mm in diameter if of iron or steel, or 12.7mm 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 1.5mm 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,lltal trencl\ where rock bottom is encountered at depth less than 1.2m.

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:

'. J.

a) where rock bottom is encountered at a depth of 1.2m 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

~l'acing

(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.

ETHIOPIAN BUII,..DINGCODE STANDARD

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170


7.8.3.7

Connection of electrodes

(1) Where separation of the different system electrodes is not possible, the electrodes shall be connectedtogether, 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 l6.0mm2 copper.

7.8.3.8

Bonding

(1) Where any or all of the separate earthing electrodes are bonded together the bonding , conductor shall be: a) a copper conductor not smaller than l6.0mm2; 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

(1) 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

(I) The earthing conductor of a wiring

system, whether also used for earthing electrical

equipment or not, may be insulated or bare, an~ 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

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ELECTRICAL INSTALLATION OF BUILDINGS .

c) rigid metal canduit, except where used undergraund ar in any lacatian where material

.

having a deteriarating effect may came into. cantact with the metal, ar in any expased raceway installed autdaars where it may be subject to. mechanical damage fram vehicular traffic, in which case a separate canductar as required in (a) abave shall be installed within the canduit; d) electrical metallic tUbing, except where used in cancrete ar masanry slabs in cantact with the graund ar in any lacatian where material having a deteriarating effect may came into. cantact with the metal, ar in any expased raceway installed autdaars where it may be subject to. mechanical damage fram vehicular tra~c, in which case, separate canductar as required in (a) abave shall be installed within"the tubing; e) the sheath af mineral-insulated cable, except when it is stainless steel, ar any canductar af a mineral-insulated

cable if it is permanently marked at the time af installatian so. that

it can be readily distinguished fram canductars that are nat used as banding canductars, except that if the sheath is af aluminium in an undergraund run ar in a lacatian where materials having a deteriarating effect may came in cantact with the metal, carrosion resistant protection suitable for the carrasive condition encauntered shall be provided; f)

the sheath af aluminium-sheathed

cable, but if used far underground runs or in lac~atians

where materials having a deteriorating effect may came in contact with the metal, c~)ITasian-resistant pratectian suitable far the corrasive canditions encauntered shall be pravided; ar g) ather metal raceways or cable armaur as provided for in Clause 7.6.6.

7.9.2

Installation of Earthing Conductors for a System

(1) The earthing canductar far a system shall be withaut jaint ar splice throughaut its length, except in the case af bus bars, thermit welded jaints, campressian connectars applied with a campressian taal compatible with the particular cannectar, ar devices acceptable far connection in series with the earthing canductor. (2) 16.0mm2 ar larger capper earthing canductar which is free from expasure to. mechanical injury may be run alang the surface af the building constructian withaut metal cavering or protectian, if it is rigidly stapled to. the canstructian; o.therwise, it shall be in conduit, electrical metallic tubing or cable armour.


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172


(3) A copper earthing conductor of IO.Omm2 shall be in conduit, electrical metallic tubing or cable annour.

(4) Metal enclosures for earthing conductors shall be continuous from the point of attachmen~ 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 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 IS.Om between pull points and does not contain more than the equival~ll_tof two quarter bends between pull points, an uninsulated earthing conductor may be used. (6) Notwithstanding the requirements of (2) above, earthing conductor of I6.0mm2 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

(1) The bonding conductor for equipment shall be pennitted to be spliced or tapped; but such splices or taps shall be }.nadeonly within boxes except that, in the case of open wiring, they shall be pennitted 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 I5.0m and does not contain more than the equivalent of two quarter bends, an uninsulated bonding conductor shall be pennitted to be used. (4) Where a t;igid 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 16.0mm2 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 16.0mm2 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 25.0mm2 or if the installation poes 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 le~s 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 IO.OmrW.

7.9.5

Eathing Conductor Size for A.C. System

(I ) 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 that.l 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-10 1995

174


7.10

EARTHING AND BONDING CONDUCTOR CONNECTIONS

7.10.1 Bonding Conductor Connection to Raceways (1) The point of connection of the bonding 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 Eathing Conductor Connections to Other-Than-Water-Pipe (1) Where

aI metal

Electrodes

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 (1) above shall be accessible.

175

EBCS-10 1995


--------------ELECTRICAL

INSTALLATION

OF BUILDINGS

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 c'over, the bonding connection continuous when the cover is removed.

shall remain

(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) a bolted clamp, b) a pipe fitting plug or other device screwed into the pipe or into the fitting, c) copper welding by the thermit process brazing or silver solder, or d) other equally substantial means.

ETHIOPIAN


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


SECTION

7

EARTIllNG, 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 this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings. (a) BS 6651: 1986

British Standard Code of Practice for Protection of Structures against Lightning, 1990

(b) NSI/NFPA78:1986

An American National Standard), Lightning Protection Code.

(c) UL 96A: 1983

Under writers Laboratories Standard for Installation Requirements for Lighting Protection systems, Ninth Edition.


EBCS-10 1995.

178

SECTION 7: EARTHING, BONDING AND UGHTEN1NG PROTECTION

7.13 DEFINITIONS (1) For the purpose Qfthis Section, In addition to the terms defmed in Section I, the following

definitions shaliapply: 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. airtermin-ation

that component of a lightning protection 'system that is intended to intercept lightnirrg flushes.

down c;onductor

a conductor intended to be used to 'carry lightningcurren:ts between air lermirration 1U1d ~arth temrimrtioo.

b-ond

'a conductor intended to prov.ide :eIectrica1 connection 'between the liglftrringprotection

system ,and 'Other metal-woiksand

·between

various porti'Ons of the latter. a mecbanica1 and/or electrical junction

joint

between

two or more

port-ions 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

ETHIOPIAN ,BUILDING CODE STANDARD

-


ring (loop) earth electrode an earth electrode fonning a closed loop round the structure below or on the surface of the earth, or within or under the foundations. It may be ~sed 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 of protection

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 systemt 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)

Copper of the grade ordinarily required for commercial electrical work, generally designated as being of 98% conductivity when annealed. ii) A copper alloy as resistant to corrosion as copper under similar condition. iii) Aluminium conductors of electrical grade aluminium. iv) Galvanized steel with cross~sectionalarea 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.


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180


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 cOlTosive gases shall be protected by a co,ntinuous hot-dipped coating of lead. (2) All components located within 610.0rnm 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 lightning-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 come 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


ltL.EC'f"RjCAbINSfALbAllCN OF BUILDINGS ,.h·.·· ..•. _ .. _ . _.

c)

Aluminium conductots and componertts shaH hot be i)embedded Ii)

in Cbncrete or masonry,;

ih direct contact with a surface coated with art alkaline base paint; m-

iH) installed in a l'Ocatibrisubject to excessive moisture. Note:'

Co'pper lightning-protection aiuminium surfaces,

components shaH not lie insfalled directly on alumihium routing, siding or other

ETH'IOPIAN 'B'UIL.O~NG CObE

STANDARD

ESCS-10 1995

1"2

S50TION 7: E:ARTHINCJ,~ONDING AND l-:'GHT~NINa P-RQT~Q'fIGN

P!m~"e!(l CO!l'lPpnent.

fie

Area

.d

Compgnent

mm~

mm Airtermination!!; ~urpir\ium, c;opper 1I11c1. gl!lvan~{l~ ~1l81

Fixe~ co""~iQl'\!l 20 lC2.5

50·9

!!trip. alu!TI!ni\lm, al\lmini\lm

8.0 dia.

~O.O

alloy, copper,

(Qond!l) In

llI.umini\J!'fl, alurnlni\lm alloy, P\lpl?llr AAd \IalV¥l~!ld st,~I;

g,?

{lxterpaj ~~p exterl'\al rodll

?Q x

ll·Odi~

5()·()

Intllmal !l'\rip interp.l!l rods

2,0 ~ 1.?

3().()

e.? dis,

~~.O

5().Q

I1ho~phor, b.rc:mze~d galvanized steel rods Flexi!?l@or larnln~ed cpnn~i9nll

Suspllndlld conductors: ~randed ah,lIT1inium

7/3.0

~rlll"1c1.e~ c;opp{lr stranglld llIuminium

1~/1.8

5p.0

llJdernal, a14miF1ium

20 x 2.5

50,0

7/3.0

50·9

e>\lemal, ,,"l1ealel;\ coppllr internal, aJurnil1lum

20 x 2.5 20 x 1.5

50.0

7/~,0

59,0

internal, aon'aJe9 Cppptlr

20 x 1.5

i30.Q

SO.Q

(~lllli reinforc{ld) §lrllOded galvanized ~lllli

(bondli);

~O.Q

P9Wl1C;qnd4ctOI"1l: 50.()

~\!mil1hJm, popper !!'ld Qalvanized steel strip ~Y!'fliF1i\lm,~l,Iminium ~19Y,pOPPllr I¥1d \J~Y~iz{ld steel r!XIs ~~h tllrrninl!tions: !!y~@nitic iron

o

cwPpn stl!l!1 w~~~ llIOS!11l~r@(1!l1~qf llpprp1
9QP!!llr!l!1d galy~ized stlllli ~rip

eoo.ONfmm' Md qf a quality n~ l!!l!!sthl'l'\ ilrade 43.OA qf ~S 4360. ihe clal;\dinil llho\llg b~ 01~.9~ p\lr!l e!ll¢.rolytlc
cQPper !lAd g~Iv!ll1iz~ stefll rOOs hard qraWn copper

be n¢ leS~.than 0.?5rnm. iQ Q!:ll,!plin\lli for \lPp'per-Q!!l~ steel r~~ lihClUld be m.ad!! frorp copPllr~silicon !l!lpy, gr~de Qfi1P1 gr Bfi

rqgs for girect ~riving into soft \Iround h!lJ"d~rawn or

¢

287~, or alumll1!\Jrp prcll'1zeallClYI\:Ira~e CA10? BS ?871. ili) The u!je intemal phosphor prClnze dowels !T'ay

8F1nealedcopper r9d~ or sQlid wires for iF1dirllgtdriving or layint! in \lround rods for h!lJ"d\:Iroung c;opp@r-c!ador \Ialvan~ecl. steel rQds (s~ nQte!!tQ tabl@) for harcler\:Ir94F1c1

FQr
¢

11.0c;jia.

50.q

givll lliower

resist8T1cethlVl the e>\le!T\aJcOlJplil1g1101

d!arnetllr gre(lter than the rog. 11;3.0

Iv) For ~1lIv,,"~!ld. lll~! rggll! steel 01 gr!l~e ~.OA !!p!!Cifi~ In B~ ~!$() sl'\@l,llgP@ \lllltd, t~{l thrl!!lds being c\ll before ~ot-dip gaiV!l"izing tel BS 7~. v) strandeq con.ql,!~o!,! "l! ngt nQrmaJly !lsed felt 9OW~ 99f191Ag!QI'l! pr I!~hll' vi) ~reater diml!nsion!l arl! r@~\lired for the 1oUpw!n~: • stl1Jcturell exceeding ?P·Qrn in tl!li~~t • Sp!.lC;i!!lc;:1~Il!lS¢. !l1l1Jglurl!l, • Mec;tl,,"icll.! or corro~lve reason!!.

183

EBCS~10199~

ETHIOPIAN SUILOIN

Table 7.4 Minimum thicknesses of sheet metal used for roofing and forming Part of the air termination net work

Material

Note:

Aluminium Zinc LeadMinimum nd0.7 2.0 Material Minimum thickness 0.5 0.3 0.4 thickness[mm]

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

750 500 1000 500 1000 Fixing centres [mm]

Arrangement

~

s

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 tenninations

shall be made of solid or tubular rods.

(2) Horizontal air terminations shall be made of solid conductor, strips or cables.


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) Ajr 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 7.15.

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


ELECTRICAL INSTALLA TlON OF BUILDINGS

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 for 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 joineQ to the down conductors of the taller portions in addition

tJt>

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.

ETHIOPIAN

---

----------

BUILDING

CODE STANDARD

EBCS-10

1995

186

SECTION'?':

EARTHING, BONDING AND liGHTENING

PROTECTION

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 7.1 7).

7.17.3 Recommended Number (I) 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 similar·location 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 cOITosive soil shall be protected against cOITosion for not less . than 91S.0mm above grade level and for entire length below grade level.

7.17.6 External Routes Not Available (I) 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 Note:

internal duct and taken straight down to ground.

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 p()ssible, access to the interior of the duct shall be available.

187

EBCS-10 1995


••


7.17.7 Lift Shafts (1) Lift shafts shall not be used for fixing down conductor.

7.17.8 Re-entrant Loops (1) When a large re-entrant loops [s~e 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 fonn an included angle of less than 90° or have a radius of bend less than 203.0mm (see Figure 7.16).

7.17.10

Bonding to Prevent Side Flashing

(1) Any metal in or fonning 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:

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.

7.17.11

Bonds

7.17.11.1 General (1) 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 (1) 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 of future equipment (1) In all buildings, at each fldor level, provision shall be mad~ for bonding futijre 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 (1) Joints shall: a) be as few as possible; b) be mechanically and electrically effective; . c) be protected against corrosion or erosion from the elements of the environment; and d) 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 o,rerlap 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, it 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


'E~eCTRICAL INSTALLATION

1.18

QF BUILDINGS

EARmTERMlNATION

1.18.1 Termination (1) Each down conductor !thall terminate at an earth electrode.

7.18.2. Re$istanee to Earth (l) Each earth electrode shall have a resistance (in ohm) not. exc~ding the product given by 10 Qf earth eleotrodes to be provided . times ti.N number . . (2) The whole of the earth termination network shall have a combined resistance to earthn<;>t exceeding 1Q ohm without taking account of any bonding to other services.

7.18..3 Eartll El~trodea 7.18.3.1 General (l)Earth

eleotrodes shall oonsist of metal rods~ tubes

Of

strips or a combinatiol.l of these Or

natural earths such as piles and foundatiol.ls (see Figure 7.20).

7.18.3.1

Earth rod cmmection

(1) 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 Conn~tion Point (1) The point of connectiol.l of the earth termination network shall be removable and easily accessible fr"Om above~earth to facilitate inspectiol.l, testing and maintenance of the Ughtnil.lg protection system. (2)

If below ground, the point of COnl.lectionshall preferably be housed in a purpose"built

... h ber. mspectlon pIt or c.am

ETHIOPIAN BUILDING CODe STANDARD

EBCS ..10 1995

190

.",

.,.,._

.._.•

SECTION B'

__

1: EARTHING,

'" ••••••

'n~·'_

•.· ••

__

.·.~u

BONDING

__ .•. _·.

__

ANDL1GHTEN1NG ". __ .••

__ ,

,_."

PROTECTION ••

'_."_"_'_'"

7.18.4.1 Deep moist clay soil (1) 'Earthing rod ,shall extend vertically not less than 3J)m into theeatth. (2) The ground shall be compacted and m:ade tight against the full leltgth of thecond:uctrrr

or

earth rod (see Figure 7.19). 1.18.4.2

to

Sandy or ,gravely soil

In sand or gravel, two or more 'earth rods at not less than 3.0m :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

(1) if bedrock is neat the surface, the conductor shan be laid in trenclres extending away from the building at each down conductor. (1) Trenches in (1) above ::shallat least be:

a) 3.7mlong b)

703m

and 610,Omm deep in day soi~

long and 610.0mffi deep in slll1dy Of gravely ~oi1-.

(3) If these methods should prove impracticablej the lightning ptoteetloncahlemay directly on the bedrock with a m1nimumdistance footing and termin'iltehy having amlnimufil 1.18.4.4

a:ttachrn:ent to a buried copper earth platea't ltlast O.:8mmthic'kand

surface area of 'O.18m2 •

Soilless than O.3m deep

(I) If soil is less than O.3m in depth, down conductors shall beconhected installed in a trench or in rock :ctevlces around thestrucmre.

to a

1000p

(2) '(1) The 100p conductor shall not be less than the equivalent of :amainsize conductor.

191

be :laid

of 610J)mm from the fomid-ation 'C)r'exterior

EBCS-10 1:995

'ETH10PtANB'UILD1NG

conductot

lightning

OODe -STANOA'AO

.ELECTRICAL INSTALLATION OF BUILDINGS ,

{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

Earth 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 Common Earth Potential (1) All earthing mediums in or on a structure shall be interconnected to provide a common earth potential. (2) The Provision in (1) above shall include lightning protection, electric service, telephone and antenna system earths as well as underground metallic piping systems; 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, teiephone, 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 WlJ,terpipe; only one connection to the lightning system is required provided that the water pipe is electrically continuous qetween all systems.


EBCS-10 1995

192


(3) If the water pipe in (2) above is not continuous, the non-conductive sections shall be bridged withmain size conductors, or the connection shall be made at a point where electrical continuity is assured.

7.20 USE OF REINFORCING BARS FOR 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).

7.20.2 Electrical (;;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 electrical continuity is ensured.

193

EBCS-10 1995



7..-21

STRUCTURAL

STEEL FRAMING FOR LIGHTNING

PROTECTION

7~21.1 Gene..,.1 (:1)

Thestrocturalsteelfr{l1llework

ofa buitding may be used as the main conductor of ,a

lightning protectiOIi system if it is either electrically continuous or made so. 1.21.2 Air Termination

(I) Air termination shall be bonded directly lothe 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
{l) COMe-ctio-n shall be

made on cleaned areas ofthe steel work by use of bonding plates with

pressure 'cable connectors ,lravingasurface 'contact ;areaof not le-ssthan 5200J~mm~; ~ol.ted, welded, or brazed securely to the steel S0as to maintainelectricalcontinulty. 7·.21.4 Earth'ing (1) £afthing

connections :shall be made ,at approximately 'every other 'sreel column around the

:perimeter and shaU not average more than n.Oma;part. (2) The earthing conductor shall be connected to steel columns using bonding plates (s'ee 7 :21.3). (3) The bonding plate shan 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 '-....

(l) Metal bodies that are required to be bonded need not be'separately

bonded if they are

electrically continuous with the lightning protection system through the steel framework.

ETHIOPIAN BUILDINGCOD~

STANDARD

EBCS-10 1995

1'94


(al

(b)

leI

1

Ie)

(d)

(QI

Note:

i)

Lightning conductor fixings should be purpose-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 1.3mm a for expansion. Conductors of circular section should he similarly· treated.

ii) All fixings should be securely attached to the structure; mortar joints should not be used.

Figure 7.1 Typical design for lightning conductor fixings

195

EBCS-10 1995



HC

--- GL~///////////// / --/\/ I

\ GL 0\

/ /' ../'"II I.\ I I \ I He

ZP lbl Horllonttl /'".•.........

.•..•.•.••

(

/

\

,.-

/ /

1"11"

view

-

-"'" .......•••.•...

ZP

ZP

PI.n vl.w 01 lont 01

\

{

vC

vC

\

\

o

0

J

>

<

{

o ve

\ \

•.•.•....••

'"

protection .t ground 01 Ion. 01 .

,...,

tlr t.rmlnttlon tt ground " --prottctlon

Ilvtl

ZP

"-..

~.

,

o

ve

../"....

--

/ ZP /

Icl Four vortlcol conductors showing protlctlVl .nd •• socltted Ion •• 01 protection.

.ngl ••

./

Figure 7.2 Protective angles and zones of protection for various forms of air termination·


EBCS-10 1995

196


Figure7.3 Typical forms of vertical air termi~ations

197

EBCS-10 1995

ETHIOPIAN BUILDINGCODI;

STANDARD


2 Rod holdliitl

€== .CEP~: 'Q 13

u

!~1

KIY

Air tormlnll

.~

3 Rod coupling

10-1 4---i1

Earth

13~t3

4 D_n conductor a Horlzontl' conductor

-$-

a Tilt lolnt 7 Elnh Ilectrodl 6Ql

Ib6.

6 • EII'th tod 'A' cllmp 7

9 Rod hOUllnl III Chimney. '"II thin 1.5 m dlomettr It top.ond 20 m hil"

10 Cond"ctor clip 11 cOronll bind 12 Bond to CI" 'ron cap II .'tornatl •• to coronll bind 1111. (bl 60 m bricl(ltlck

Note

13 Junction cllmp

This figure, does not apply to reinforced concrete chimneys where the reinforcing bars can be used as down conductors

Figure 7.4 Examples of lightning protection systems for brick chimneys


EBCS-10 1995

198


Bimetellic joint

Galvanized steel roof

Reinforced concrete Ilructure with parapet, Ilone coping and non-conducting roof

Bonds to steelwork

Reinforced concrete structure, PVC coping with conducting roof

Bond to metal suspended

ceiling

4 One reinforcing

ber shown for clarity

3

4

Detail showing

item 4 Key

1 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

reinforcingbars.

199

EBCS-10 1995

ETHIOPIAN BUILDING ,CODE STANDARD


___

Bolted joint connecti on 2 •• M 8

Beam

Note:

Minimum dimensions when a metallic roof covering is used as part of the air termination follows: galvanized steel copper aluminium

IO.5mm O.3mm O.7mm

zinc lead

network are as

O.7mm 2.0mm

Figure 7.6 Air termination for flat roof sbowing connection to standing seamjoint when a metallic roof is used as part of tbe air termination network


EBCS-10 1995

200

SECTION 7: EARTHING, BONDING AND LIGHTENING PROTECTION '

HC

,

l~",

/:s:j Ie) Elevation .howing protective .ngle

'"

I HC

. II I

"

\

HC

,

I II

HC

'Oml mall.l

He

___

L

20m

ZP_

--_/

/

/

Ib) Plan .howlng zone of protection at ground level

Ic) Gen.rel .rrangement

]figure 7.7 Air terminations for a flat roof

201

EBCS-10 1995


ELECTRICAL

Note:

i)

INSTALLATION

OF BUILDINGS

If S> 10+ 2H, additional longitudinal conductors are required so that the distance between conduc~rs does not exceed lO:Om.

ii) If the length of the roof exceeds 20.0m, additional transverse conductors are required. iii) Down conductors are omitted for clarity.

Figure 7.8 Air terminations for large areas of roof various profiles

ETHIOPIAN

BUILDING

CODE STANDARD

EBCS-1 0

19~5

202


Test joint·

Test

Test joint

joint .....••.. DC

DC

'"

DC

I I I

I I I I I I DeL

16 m 16 m

(1) Note:

16 m

20 m

(2)

(3)

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 IO.Om x (IO+2H)); ridge and eaves conductors provide approximate roof mesh 6.0m x lQ.Om;number of down conductors=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'an"

down conductors Vertical air terminatinn

Conductor 'or strip rOd or metallic gulter

Rfdge conductor fixed below tile -'e~el (see detail)

Key:

Conceald conducto~

D.t.1I

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 with stopping roofs

203

EBCS-10 1995

ETHIOPIAN BUILDING QODE STANDARD

ELECTRICAL

INSTALLATION

,

,..

"-

,,-

OF BUILDINGS ,,-

'.....-

View from B

-Join down conductor. and horizontal conductors on lower parapet. Section A·A

/I

-.

-#---r

Il-oc

fa

12 m

II ..

I

[J

DC A 112 6m

.1

Dc"1

t

[J I

Hell

II

Perimeter ••24 + 24 + 12 + 12 •• 72 m • Number of down conducton rel.1\Iired

72/20 ••4.

Note:

i)

An.air tennination 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 1.0m 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

?ECTION 7: EARTHING, BOND1NG AND LIGHTENING PROTECTION

El-

::[ OM' I ...

Note:

i)

Horizontal

air tennination

DC 60 m

DC

•.../

conductors should be jointed at the interconnections.

ii) Where PVC covered horizontal air tennination

conductors are used, bare vertical rods O.3m high should

be fixed at each intersection and at intennediate

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 tennination

network for a tan reinforced concrete or steel framed structure should be as fonows:

conductors on roofs from a IO.Om x 20.0m network.

(a)

Horizontal

(b)

There are bonds to steelwork at corners, 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



Roof conductor

*

represents a bond to roof steelwork. Note:

i)

The horizontal

conductor mesh size should be 5.0m x 1O.Om or smaller, according to the risk.

ii) For clarity, down conductors are omitted.

Figure 7.13 Air termination network with horizontal conductors for structure with explosive or highlYJlammable contents


EBCS-10 1995

206


Sm

Fl't n,:p conductor f.lt.n.d to plnp.t will

,I

,

,I! .9

9,I,

9t Ii,

,

I

I9 ,I,

I'

-.

Koy

~

on metal roofs, these conductors may be omitted. 1 Air termination

7

Eaves conductor

2 Down conductor

8 9

Test point Earth electrode

10

3 Bonds to holding dowp rod 4 Horizontal conductor 5 Vertical conductor

11

Main earthing terminal of Electrical Bond to bell-frame

6 Ridge conductor

12

Peripheral conductor

Note:

i)

installation

The air termination network should have a 1O.Oll} x 20.0m mesh. For structures below 20.0m hight, there should be down conductors every 20.0m of periphery and for structures over 20.0m high, every 10.0m of periphery;

horizontal conductors should be every 20.0m from the top.

ii)

Metal roofs may be suitable as air terminations

iii)

On shingle spires, metallic soakers and gullies should be bonded at the top and bottom.

(see Table 7.5 and Figure 7.17).

Figure 7.14 Church towers and spires

207

EBCS-10 1995


ELECTRICAL INSTALLATION OF BUILDINGS Suspended

air

termination

See note 2

Mast

See ,note 2

See note 2 Protected

~Earth

building

electrode~ lat Elevation

-

Suspended

Suspended

air

Protect.ed

air termination

termination building

(b} Plan Kay \

-

-

---

-

Zones of protection It m.st\ Zones of protection

x --

+\

It

maximum sag of '\

leri.l conductor

:'\\ 'II-

Protected building

\

\

\

\

(el End .I ••.• llon showing zones 01 prote<:tlon

Note:

i)

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°.

ii)

To prevent flashover between mast/conductor has to be 2.0m or as under

and protected building, the minimum clearance distance

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


R

••

RilclillS of bolnd. 8 inchus (203 mOll minimlim.

Figure 7.16 Sharp bends

209

EBCS-10 1995


l


•• • •• i

1.1

••

••

11/

•

ldl

t

Note:

L

-----.

.•• • :LJ= • Itl· • ,I.• ••

•

N

•

•

T3

i)

The down conductors may be natural part of the building framework or added strips or rods on external faces.

ii)

On structures exceeding 20.0m in height, down conductors should be spaced at not more than apart.

1O.Om

Figure 7.17 Pattern of down conductors for various forms of tall building


EBCS-10 1995

210

~


ad maximum

Exceeding ad

,

d"

i

"~

I

(a Permissible

arrangement

(bl Arrangamant

permissible Not

--tII

that is not permissible

~Permisslble I

t

I

lcl Permissible melhod of taking conductor through a pllrapat wall

ldl Routlli for, down conductor" with cantilevlIrtld uppllr lIoon

in a building

Figure 7.18 Re-entrant loops

211

EBCS-10 1995


ELECTRICAL.

INSTALLATION

OF BUILDINGS

A=

o.6~m mini~um t

B= 3.0P m mini~Um

. Figure 7.19 Earthtng in ~oiBt Clay ·~oil.

Figure 7.19 Earthing in moist clay soil


EBCS-10 1995

212

Ai,. termination bonded to steel reinforcing or steel frome of building

Air termination

on roof

Down conductors lin these caSes steel rei,. forc ing or steel frame of building I

Ring earth electrod~ below ground level to improve earthing(~,

1111 _~

.•....J •... IJJ •...•...

~;.,/

..•...

, ./ 11l " ./

....

"

<~)

Bonds to lift installations at top and bottom of continuous rigid metal structure only

'I I

I

I ~

Earth

Ground level

electrode

NOTE. Air tennination mesh should be not •. eat•. tun 10 m X 20 m. Down conductors should be not more tNn 10 m ~art.

Fig ••.• 7.20 Ligbtning protedio.

system ror tall b.ildings (over 20.0m bigb) sbowing air termi.atinns.

down cond.cto •.••bonds to projectinns above roor

ELECTRICAL

INSTALLATION

OF BUILDINGS

ternate A =10.610 a =

configuration

mminimum

13.00 m minimum

Figure 7.21 Earthing in sandy or gravely soil

ETHIOPIAN


EBCS-10

1'995

214


,/ ,/

--
'",,'''plate

. Loop conductor

Figure 7.22 Earthing in soilless than O.3m deep

215

EBCS-10 1995



.. ~

0' . 0

• , .0

o

",

." "

0

. 0:.

0,,' o

Concrete

, ' o

..

..

,~'

,

,

.

. 0 • ,

.

• D

b

,0

,

b

•

,~

"

,P

,

.'0 ,0

1ft}!..-~/;~,??-.~/.;?·:~~~,~:';:~:i'·" . ~'.'"

,4

"-' :*:1.'

" ., Asphalt

1I ': 0111

0: ,'

0, .'

Asphalt

/" Concrete

?, 'n

.0 . 6'

:.

<:>

.'"

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

I, ExterMl down conductor..-..provfde

sea ed tube

nt~ For Test cavityJolallS

I Lightning protection earth termination netv~ Electr~city

"

cable

, ...-, t

Water

\ t

Gas

k I \0"

1#' ••••• (-

,

"

,,.

( •••• ' \

... 11,.0:

,

I ••• ' •• \

l' J',.,'" . ,, ,,. ..i- ,,~..,..... .'

,,,..,

,..

I \~

Figure 7.24 Diagram showing bonding to services(gas, water and electricity)

NOTE.

Corrosion

inhibitor

to be used

on all

Figure 7.25 Testing joints

217

EBCS-10 1995



Bonding plate with a minimum contact area 'of 52 sq. mm

A :::O.61m mini mum B = 3.00 m minimum

Figure 7.26 Earthing connection on structural framing


EBCS-10 1995

218

ANNEX

A

(INFORMA11VE)

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 t~ positioning of all the component parts of a lightning 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 con~ucting 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


ANNEX

B.t

B (CONSULTATION)

GENERAL

Consultation should take place between the designer of the lightning protection s'ystem and the interested parties indicated in Clauses B.2 through B.6 before and during all stages of design.

B.2

ARcmTECT

/ ENGINEER

As far as practicable, the following should be detennined: a)

Routing of ,illl conductors.

b)

General areas available for earth tennination 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 tennination 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 INSTALLERS

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: the builder;

a)

the form, positions and numbers of primary fixings to be provided

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

by

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 weather-tightness of the structure;

j)

with

a view to maintaining

the

possible penetration of a waterproofing membrane where earth terminations have to be sited beneath the structure, especially in 'urban' situations and in confined spac.~s 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;

I)

the provision of bonding connections to a sted 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: (a) conductors which form an integral part of factory built equipment; (b) communication

circuit, unless otherwise specified in Section 23;

(c) Class 2 circuits, unless otherwise specified in Section 10; (d) community

antenna distribution,

radio and television installations, unless otherwise

specified in Section 24; (e) optical fiber cables. 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. (a) C22.1:1992

(b) BS 767:1992

Canadian Electrical Code Part Installation, Sixteenth Edition The electricians

I, Safety Standard for Electrical

Guide to the 16th Edition of the lEE Wiring

Regulations, Second Edition, 1993

8.3

GENERAL REQUIREMENTS

8.3.1 Methods of Installation (1) The methods of installation of wiring systems shall be as shown in Annex A.

. ETHIOPIAN BUlLDING CODE STANDARD

EBCS-l0 1995

223

ELECTRICAL

INSTALLATION

OF BUILDINGS

(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 c?ver requirements shown in Table 8.1. Table 8.1

Minimum cover requirementst for direct buried conductors, cables or raceways

750.0Vor 1000 600 750 900. Over Over 750.0V 750.0V armour sheath Qr armour Conductors or cables Raceway

Non-vehicular area. Ie•• 450 600 Vehicular area. Minimum cover [mm]

Minimum cover means the distance between the top surface of the conductor, cable, or raceway and the finished grade.

224

EBCS-10 1995

ETHIOPIAN


SECTION 8: WIRING METHODS

(2) The minimum cover requirements shall be permitted to be reduced by IS0.0mm where mechanical protection is placed in the 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 SO.Omm beyond the conductor, cables, or raceways on each side: (a) Treated planking at least 38.0mm thick. (b) Poured concrete at least SO.Ommthick. (c) Concrete slabs at least SO.Omm thick. (d) Concrete encasement at least SO.Ommthick. (e) 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 IS0.0mm 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 1OO.Ommin thickness, the location is adequately marked, and the raceway will not be subject to damage during or after installations. (6) Any form 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 Hoistways

(1) Where conductors other than those used to fumish 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

r


(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 installed 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 particul.ar respect ..to the follwing (a) moisture (b) corrosive action (c) temperature (d) degree of inclosure (e) 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

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EBCS-10 1995



Table 8.2 Minimum internal radii of bends in cables for fixed wiring

Type of Insulation

Mineral-insulated

a410.0m over to 25.0mm 25.0mm Overall diameter (3)factor 3at (2) up todiametre 10.0mm any Bending

cables may be bent at a minimum radius of three times the cable diameter provided that they

will only be bent once.

Note:

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

pye

cables when.installed

in conduit,

trunking or ducting.

8.4.3

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

227

ELECTRICAL INSTALLATION OF BUILDINGS , I

8.4.4

Supporting of Conductors

(1) 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

I

I:

550 400 1500 450 350 Horizontal Vertical Vertical 800 400 900 600 300 2000 1- 250 121)0 MBximum sp,cing of clips [mm] Horizontal Min",f.insul,tBd c,bllS I ShllthBd c,bllS

~

Note:

For the spacing of supports for cables of overall diameter exceeding 40.0mm. and for single-core cables having conductors of cross-sectional should be observed.

8.5 8.5.1

area 300.0mm2 and larger, the manufacturer's

recommendations '.

OPEN WIRING Open and Clipped Direct

.(L) 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



8.5.3 Conductor Supports (1) 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 (1) 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

(I) 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 mechani<;:al 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 rooI, 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 ~ommunication 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 l200.0A or less: Note:

i)

Where flat bus bars 6.25mm or less in thickness are used, the continuous current rating shall not exceed 1.6A/mm2 of cross-sectional

area of copper bus bar or 1.12A/mm2 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 FITTINGS

OF

BOXES,

8.8.1

Number of Outlets per Circuit

CABINETS,

OUTLETS

AND

TERMINAL

(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 1.0A 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



8.8.2 Outlet Boxes (1) 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 kllob-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 of 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 in (1) above shall not be used at outlets for fixtures.


EBCS-10 1995

231

ELECTRICAL INSTALLATION OF BUILDINGS L

8.9

CABLES, CONDUCTORS AND WIRING METHODS

(1) Every cable operating at low voltage shaH 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

E13cs-10 1995


s

ANNEX SCHEDULE

Note:

A (NORMATIVE)

OF METHODS OF INSTALLATION OF CABLES

i) The methods of installation distinguished by bold type are reference methods for which the currentcarrying capacity given in Annex B, Tables B.I through B.45, Section 4, have been determined. ii) For the other methods, an indication is given of the appropriate current-carrying capacity which can safely be applied.

2 3 Installation method for 4determining Reference Method

Open and clipped direct:

Sheathed on a non-metallic cables clipped surface'.direct to or lying : ~ Cables embedded direct in building materials:

2

Sheathed cables embedded directly in masonry, brickwork, concrete; plaster or the like (otHer than thermally insulating materials)

reference method having values of

Appropriate capacity

current-carrying

J~

11~

Method 1

Method 1

In conduit:

3

Single-core non-sheathed cables in metallic or non-metallic conduit on a wall

Method 3

or ceiling Single-core non-sheathed cables in metallic or non-metallic conduit in a

4

5

thermally insulating wall or above a thermally insulating ceiling, the conduit b~ing in contact with a thermally conductive surface on one sidet Multicore cables having non-metallic sheath, in metallic or non-metallic conduit on a wall or ceiling.

Method 4

Method 3

tThe 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 fixed 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

Appropriate Reference Method for determining current-carrying capacity

Examples

Description 2

6

Sheathed cables in conduit in a thermally insulating wall etc. (otherwise as Reference Method 4)

7

Cables in conduit embedded in masonry, brickwork, concrete, plaster or the like (other than thermally insulating materials)

3

4

lc:Q

Method 4

Method 3

p ..

In trunking:

-

--'-, ,

.

8

Cables in trunking on a wall or suspended in the air

9

Cables in flush floor trunking

10

Single-core cable in skirting trunking

Method 3

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

Method 3 Method 3

On trays: 11

In free air, on cleats, brackets or a ladder

12

Sh••athed single-core cables in free air (any supporting metalwork ';'Ider the cables occupying less than 10% of the plan area): Two or thr'le cables vertically one above the other, minimum distance between cable surfaces equal tc, the overall cable diameter (D.); 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


SECTION 8: WIRIN.G METHODS

Installation method Number

Examples

Appropriate Reference Method for determining current-carrying capacity

3

4

Description 2

In free air, on cleats, brackets or a ladder

13

14

Sheathed multicore cables on ladder or brackets, separation greater than 20. Sheathed multicore cables in free air distance between wall and cable surface not less than 0.3D.Any supporting metalwork under the cables occupying less than 10%the plan area Cables suspended from incorporating a catenary wire

(~[

~

Method 13

Method 12 or 13, as appropriate

or

-----------

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

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: --i-) 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

ELECTRICAL INSTALLATION OF BUllDtNGS

Installation method Examples. Number

Description

I

3

2

Appropriate Reference Method for determining current-carrying capacity 4

Cable In trenches:

17

Cables supported on the wall of an open or ventilated trench, with spacin~as indicated for Reference Method 12 or 13 as appropriate Cables in enclosed trench 450.0mm wide by 300.0mm deep (minimum dimensions) including 100.0mmcover

18

a

~

~ n~r;p ~ _.LL F/. /L

~

~

?;,#l / ///~ //'r;

a------t 0-9/),/9/~ Cables in enclosed trench 450.0mm wide by 600.0mm deep (minimum dimensions) including 100.0mmcover 19

Method 12 or 13, as appropriate

Two single-core cables with surfaces separated by a minimum of one cable diameter. Three single-core cables in trefoil and touching throughout. Multicore 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 minimum! of 75.0mm. All cables spaced at least 25.0mmfrom the trench wall Cables in enclosed trench 600.0mm wide by 760.0mm deep (minimum dimensions) including 100.0mmcover

~

20

V

;;]0 0 ~o

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.

0

o~

o~

~o 0 ov.: ~o 0 o~ / ////////,

Groups separated by a minimum! of 75.0mm either horizontally or vertically.

Method 20. Use rating factors in Table A.3, Section 4.

All cables spaced at least 25.0mmfrom the trench wall.

! Larger

236

spacing to be used where practicable.

EBCS-10 1995


9

SECTION

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


(I) 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

(1) Every

Installation,IEE

. Wiring

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;


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 mllst be interrupted. 9.4

PROTECTIVE

9.4.1

Overcurrent

DEVICES Devices

(1) Each unearthed conductor shall be protected by an overcurrent device at the point w.?ere 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, panel board, control device which it supplies; or (c) the smaller conductor has an ampacity not less than one-third that of the 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


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.OV 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 l200.0A and the maximum time

-

delay shall be 1.Os 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 be 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,: v(a) an overcurrent devic~ which incorporates earth-fault protection;

1)/

v(b) earth-fault trippi.ng system.comprising a senso~ or sensors, relay and auxiliary tripping mechanism; or ./( c) other appropriate means.


EBCS-10 1995

239

J..


9.5

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 have'ratings 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 or 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 mean~, 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

. (1) 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) mted 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

63 80 40 100 125 350 400 450 32 400 600 16 20 25 32 50 100 200 110 150 175 225 250 300 500 600 200 16 50 2 40 63 100 150 175 250 500 0breaker Rating or setting permitted Circuit Fuse


[A]

EBCS-10 1995

243

Table 9.2 Overcurrent trip coils for circuit breakers a~d overload devices for protecting motors neutral conductor earthedtt 2 32-phase conductor earthed conductor Kind of motor Number and location of overload in any except one one ininconductor each each phase, phase not For toa neutral be 2-wire 3-wire, a.c. or d.c., a.c. unearthed unearthed or or with with oneForormotor 5-wire, 1-phase or d.c. d.c., with earthed 4-wire, 3-phase 1-phase cqpnected 3-phase a.c., a.c. with a.c. in or any d.c. earthed neutral neutral conductor System devices such as trip coils relays, 4--wire,2-phase a.c., unearthed circuit or protection t2-phase overload protection 1 2-trip coils, one in each outside 4-trip coils, one in each unearthed

arthed

t

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 an 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 them from electric light and power circuits and, therefore, alternative requirements to'those of other relevant Sections of this Code with regard to minimum wire sizes, de-rating factors, overcurient protection, insulation requirements,

10.2

wiring method, and material are deemed necessary.


(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) NFP A70/NEC: 1986 National Fire Protection Association! American National Electrical Code, 1987 Edition. (b) C22.I:1992

10.3

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

CLASSIFICATION

10.3.1 General

{i) CirCUItscovered 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 defmed below: (a) Class 1 - Circuits which are supplied from sources having limitation in accordance with Clause 10.4.1.


EBCS-10 1995

245

•


(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 (1) Circuits which are neither remote-control circuits nor signal circuits, but which operate at not more than 30.0V 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. OVA shall be clasefied as extra-low-voltage power circuits and shall be considered to be Class 1 circuits.

10.3.3 Class 2 Low-Energy Power Circuits (1) 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 (1) Where the circuits or apparatus within the scope of this Section are installed in hazardous locations, they shall also comply with the applicable Clauses of Section 12.

10.3.5 Circuits to Safety Control Devices (1) Where the failure to operate a remote-control circuit to a safety control device v rill introduce a direct fire or life hazard, the remote-control circuits shall be deemed to be a Class 1 circuit.

10.3.6 Circuits in Communication Cables (1) Class 1 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 applicable Clauses of Section 23.

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EBCS-10 1995

circuits and shall conform to the req~irements of


----

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.OV A.

(2) Class I remote-control

and signal ~ircuits shall be supplied by a source not exceeding

600.0V.

10.4.2 Methods of Installation for Class 1 Circuits

(1) The equipment and conductor of Class I circuits shall be installed in acc?rdance with the requirements of other appropriate Sections of this Code, except as provided in\Clauses 10.4.5 through 10.4.10.

10.4.3 Overcurrent 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 (b) where the conductors are of 1.0mm2 copper and extend beyond tIle equipment enclosure, they shall be protected by overcurrent devices rated at a maximum of 5.0A and 10.0A, 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 othttr than the normal overeurrent protection of the branch circuit supplying the transformer.

10.4.4 Location of Overcurrent Devices in ClfSs 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 integral part of the power supply.


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247


10.4.5 Class 1 Extra-Low-Voltage Power OrclIit Sources Including Transformers (1) To comply with the 1OOO.OV A limitation, Class 1 extra-low-voltage

power circuit sources

including transformers shall not exceed'a maximum power output of 2500.0V A; and the product of the maximum current and maximum voltage shall not exceed lOOOO.OV A 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 cord 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 1.5mm2 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 1.0mm2 or 1.5mm2 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 enclosure, cable or raceway.

in the

(2) Power supply conductors and Class 1 circuit conc'uctors 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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EBCS-10 1995


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.

Class 1 Circuits Extending Aerially beyond a Building

lO.4.10

(I) 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 1.0min;

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 exceeding

lOON

amperes,

where V is the open-circuit

protection rating not

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 1.0min;

ii) a C;:lass2 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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249

ELECTRICAL INSTALLATION OF BUILDINGS c) Over 30. OJ' but not exceeding 60.0.,,: Circuits in which the open circuit voltage exceeds 30.0V. but does not exceed 60.0V, shall have an.,overeurrent


exceeding lOON ampers, where V is the open-circuit voltage, except that the overcurrent pro~ection 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 60.0'" but not exceeding

J 50.0.,,:

Circuits in which the open-circuit voltage exceeds

60.0V, but does not exceed ISO.OV, shall have an overcurrent


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 I OO.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 coriductors and equipment protectidh, transformers, requirements

or current-limiting

on the supply side of overcurrent

devices shall be installed in accordance with the

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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EBCS-10 1995


SECTION 10: CLASS 1 AND CLASS 2 CIRCUITS (2) The overcurrent protection may be 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 supply.

10.5.6 Conductors for Class 2 Circuit Wiring (1) Conduct<;.}[Sfor 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 1.5mm2 and smaller, but in no case shall it exceed the current limitations of Clause 10.5.1.

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 380.0Y 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 380.0Y unless for both conditions effective separation is afford by use of:

a) metal raceways for the Class 2 circuits or for the dectric 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 I circuits operating at 380.0Y 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

110

opening, such as an outlet box, may be located within 2.0m of the bare conductors if up to and including 15.0kY or within 3.0m of bare conductors above 15.0kY. (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

ETHIOPIAN BUlLDING CODE STANDARD

EBCS-10 1995

251


shall not be placed in any raceway, compartment, outlet box, junction box or similar fitting with the conductor of electric lighting, power or Class I 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 mld 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 Sic;leof Overcurrent Protection, Transformers, or Current-Limiting Devices for Class 2 Circuits

(1) 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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EBCS-10 1995


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 Clause 8.3.3.

installations

of Class 2 circuits shall be installed in accordance

with

(2) Direct buried Class 2 circuits shall maintain a minimum horizontal separation of 300.0mrrl from other underground systems except when installed in accordance with (3) below. (3) Direct buried Class 2 circuits may be placed at random separation in a common trench with power circuits which are for the sole purpose of 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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253

SECTION

INSTALLATION

1

rECTRICAL 'UIPMENT

11.1

SCOPE

(1) This Section applies to the installation of the following electric equipment: a) Heating and cooking. b) Submersible pump. c) Motors and associated circuits. d) Air conditioning. e) Refrigerating. f) Storage batteries.

11.2


(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)

NFP A 70/NEC: 1986

National

Fire Protection

Association! American

National

Electrical Code, 1987 Edition. (b)

11.3

C22.1:

1990

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.

254

EBCS-10 1995


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 equipmentl that surface shall be covered with a steel plate at least 1.6mm thick and which shall extend at least 150.0mm 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) Yentilated 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 ~arth 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 230.0Y branch circuits protected by overcurrent devices rated or set at not more than 16.0A shall not exceed 1500.0W at 230.0Y.


EBCS-10 1995

255


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, ar~ 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 • twisted assemblies of this types; or

cable, single conductors or

b) extra-hard usage type, or the equivalent portable cable.

256

EBCS-10 1995



(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

Wiring 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 75°C 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 exc~ss of 75°C, 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 100.0hp 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.


EBCS-10 1995

251


(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 % 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)

125% of the full-load current rating of the motor having the largest full load clllTCnt 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;

(b)

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

(c)

motors; or

the total of the following where the group consists of two or more motors of both continuous and non-continuous-duty

types:

i)

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 noncontinuous duty motors.

(2) Where the circuitry is so interlocked as to prevent all motors of the group from running at the same time, the siLe 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 (1) above.

258

EBCS-10 1995



(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 or setting of the overcurrent devices protecting them is in accordance with 11.7.2.3(4) below.

11.7.1.6 Feeder conductors (l) 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 shaH be permitted to be calculated in accordance with 11.7.1.4 and 11.7.1.5 if the tap: (a)

does not exceed 3.0m in length and is enclosed in metal; or

(b)

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.

11.7.1.7 Secondary conductors (1) Conductors connecting the secondaries of wound rotor motors to their controllers shall have ampacities not less than: (a)

125% of the rated full load secondary current for continuous-duty motors; or

(b)

the percentage of rated full lmid specified in Table 11.2 for non-continuous-duty motors.

(2) Ampacities of conductors connecting secondary resistors'to t_heircontrollers shall not be less than that determine

EBCS-10 1995

259

ELECTRICAL INSTALLATION OF BUILDINGS ,-

11.7.2

Overcurrent Protection

11.7.2.1

Branch circuit overcurrent protection

(1) 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)

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 11.7.2.4.

11.7.2.2

Overcurrent protection marked on equipment

(1) Where the characteristics

and rating or setting of a branch circuit protective device are

specified

of motor

in the marking

notwithstanding

260

CGntrol equipment,

they

shall not be exceeded,

any greater rating or setting permitted by 11.7.2.1.

EBCS-10 1995


SECTION 11: INSTALlATION OF ELECTRICAL EQUIPMENT

11.7.2.3 Feeder ovt'rcurrent protection (1) For a feeder supplying motor branch circuits only, the rating or setting of the feeder overcurrent deviee shall not exceed a maximum value calculated by determining the maximum rating or setting of the overcurrent device pem.itted 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) pfotecting a feeder shall not exceed the ampacity of the feeder, except as permitted by applicable Clauses of Section 8.

11.7.2.4 GrfJuping of motors on a single branch circuit (1) Two or more motors shall be pennitted to be grouped under the protection of a single set of branch circuit overcyrrent 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:


EBCS-10 1995

261

ELECTRICAL iNSTALLATION OF BUILDINGS

(i)

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.

(c) 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 100.0A at voltages from p1.0V to 750.0V.

(d) All the motors are operated

11.7.2.5

by a single controller.

Instantaneous-trip cirettit interrupters

(1) 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% of the motor fullload 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

Overload protection requited

(1) The branch circuit conductors and control equipment of each motor shall have overload protection, except as permitted by 11.7.3.5

262

EBCS-10 1995



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 in 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 which shall be:

elements

(a) connected directly in the motor circujt conductors as required by (1) above; or (b) fed by two or three current transformers so connected that all 3-phases will be protect~d.

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 the 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 1.0hp 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 1.0hp 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 ofa 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 overcurrent device is in the motor circuit during the starting period.

11.7.3.7 Automatic restarting after overload (]) 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

(I) Each motor shall be provided with means of overheating protection except as permitted by 11.7.3.10. 11.7.3.9

Types of overheating protection

(I) 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 (l) 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 100e higher than those at the location of the overload devices; and Oi) 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 for 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:


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265


(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

(1) The protection specified in 11.7.4.1 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 serv~s. (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 Y3hp or 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 Y3hp, 230.0V controlled by a horsepower rated singlepole motor switch.

266

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11.7.5.2

Control location

(1) A motor controlled

manually,

have the means of operation

(a) that safe operation

by the controller

shall be guarded or enclosed

the danger

accidents

due to contact

of accidents

because of the type, size or location

and its parts, devices shall be provided

exists whereby

the machine

at each point where

or parts of the machine

may be

in an emergency.

Starters having different starting and running positions

(1) Manual motor

starters

having different

so that they cannot

remain

in the starting position.

(2) Magnetic

motor starters having different

so that they cannot remain

11.7.5.4

so as to prevent

with (a) above is not practicable

of the motor or machinery

11.7.5.3

driven by it is assured, or the motor

with live or moving parts; or

(b) where compliance

stopped

so located:

of the motor and the machinery

and the machinery of persons

either directly or by a remote control ofa motor starter, shall

starting and running

positions

shall be constructed

starting and running positions

shall be constructed

in the starting position

under normal

operating

conditions.

Earthed control circuit

(I) When power earthed system,

for a control the control

from the controller

circuit

to any remote

(a) start the motor;

11.7.6 Disconnecting (1) Except as permitted for:

controller

shall be so arranged

is obtained

that an accidental

conductively

from an

earth in the wiring

or signal device will not:

or

(b) prevent the stopping device in the control

of the motor circuit.

by the normal

operation

of any control

or safety

Means by (2) and (3) below, separate disconnecting

(a) each motor branch (b) each motor

circuit for a.motor

means shall be provided

circuit,

starter or controller,

and

(c) each motor.


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267


(2) A single disconnecting means shall be pennitted to serve more than one of the functions described in (1) above. (3) A single disconnecting means shall be pennitted 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 them shall 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 (1) A room air conditioner s.hall be considered as a single motor unit in detennining its branchcircuit 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 individual motor currents.

nameplate rather than

(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, t. 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 of a 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.

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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 230.0Y 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 (I) 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 (I) Storage, battery rooms or areas shall be adequately ventilated. (2) Storage batteries shall not be subjected to ambient temperatures greater than 4SoC or less than the freezi~g point of the electrolyte.

11.9.3 Battery Vents (1) Yented cells shall be equipped with flame arresters. (2) Sealed cells shall be equipped with pressure-release vents.

11.9.4 Battery In~tallation (1) Battery trays, racks and other surfaces on which batteries are mounted shall be: a) level, b) protected against corrosion from the battery electrolyte,


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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 IO.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 (l)

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) bare conductors which shall not be tapped; b) open wiring; c) a jacket flexible cord; d) 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 corrosion;

material suitably protected from

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


eg


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 temp.erature of 30°C)

75 90 90 110 110 H B F

75

Insulation

class rating

A

ventilated

Table 11.2 Conductor sizes for motors for different service requirements 60-

rating 85 120 95 140 150 90 200

minute ous minute Continu rating motor Operating raising' or lowering Rolls, ore-and coal-handling turntables, etc.valves, Freight Intermittent duty and passenger elevators, Varyng Periodicduty duty

110 110 85Percentage


of nameplate 30-and current

rating of

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271

,....


TABLE 11.3 Conductor sizes in the secondaryCircuits of motors

I

I'

II

Resistor duty classification

Light staring duty Heavy starting duty Extra heavy starting duty Light intermittent duty Medium intermittent duty Heavy intermittent duty Continuous duty

Duty cycles

Carrying capacity of conductors In percent of full-load secondary circuit

5 see on 75 see off 10 see on 70 see off 15 see on 75 see off 15 see on 45 see off 15 see on 30 see of 15 see on 15 see off

35 45

55 65 75 90 110

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 Type of Motor

Tlmedela y fuses

tlmedelay

Maximum settlngJlmelimit type circuit breaker

175

300

250

175

300

250

175 175 150

250 200 150

200 200 150

150

150

150

. Maximum fuse rating Non-

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

I'i

Direct Current Note:

272

(i)

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. (H) Synchronous motors of the low-torque, low-speed type (usually 450.0rpm, 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. (Hi) For the use of instantaneous trip (magnetic only) circuit interrupters in motor branch circuits, see 11.7.2.5.

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l

Fuses

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). breaker Breaker breaker Non-time Starting) Maximum Non-time conductor rating 5.00 allowable 1.25 15 1.125 1.125 2.50 15 2.25 20 1513.75 2018.75 2017.50 15 15 30 25 20 40 35 15 13.75 16.25 12.50 10.00 15.00 11.25 12.50 13.75 15.00 1.25 30 45 25 40 17.50 18.75 17.5 10 1 15 925 ofofof 10.00 1'5 6.25 7.507 8.758 7.50 8.75 20 25 3.75 6.25 5.00 4.5 3.5 5.6 or wound rotor a.c. fuses Fuses Maximum 20 16.25 Timedela Time overload devices Overload d.c. protection for cage Minimum squirrel Single phase, and all synchronous types and 2.25 ampacity Type for motor circuitsallowable [A] Overcurrent protection maximum rating of fuses and delay yy"O" "0" "0" delay Starting) setting delay .F·5 Reactor (Full voltage, Resistor and fuses Circuit Circuit (Autotransformer and Maximum Star-Delta allowable setting of circuit breakers of the time-limited Squirrel cage and Synchronous motor [A] I

15

Table

11.5 Sizes of conductors, fuse ratings, alld 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).

Fuses

Non-time delay (Autotransformer and Star-Delta 100 Non-time 40II ..II delay fuses rating 50.0 50.0 50 21.25 22.50 20 of of 80 30.0 32.5 30.0 32.5 30 ) and 100 70 60 40 45 50 50 70 40 30 60 5045.0 4040.0 4037.5 70 80 60 125 110 100 23.75 90 47.5 45.0 42.5 40.0 37.5 35.0 47.5 42.5 35.0 60 45 40 35 allowable 35 25.00 60 27.5 27.5 25 25 30 25 20.00 20.00 50 17.5 overload devices Minimum or wound rotor a.c. fuses fuses conductor Timedela Time Overload d.c. protection forcage Maximum Fuses Overcurrent protection rating fuses and Maximum allowable Type for setting motor ofcircuits circuitallowable breakers [A] of the oftime-limited yy"O" "0" "0" Single phase. all synchronous types andmaximum ampacityof setting 23.75 I (Full Reactor voltage, Starting) Resistor and cage squirrel Circuit Circuit breaker Circuit 20 25.00 Breaker breaker Starting) Squirrel and Synchronous 50

Fuses

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).

Non-time delay Starting) (Autotransformer and Maximum Non-time 70 200 77.5 60 100 '175 100 125 60 125 7072.5 110 100 7067.5 1-00 150 70 200 80 90 175 125 110 150 90 80 70 175 100.0 225 250 175 150 125 75.0 77.5 8 65.0 62.5 87.5 9 97.5 250 100.0 60.0 57.5 55.0 52.5 67.5 65.0 62.5 82.5 60.0 57.5 55.0 70.0 72.5 75.0 80.0 85.0 87.5 90.0 92.5 97.5 52.5 95.0 0.0 2.5 5.0 .7 6 8 50 9rating 90 0 ofof allowable Fuses fuses fuses Starting) Timedela Time overload devices conductor d.c. or Maximum wound rotor a.c. Maximum Minimum 7070.0 Overload protection for Star-Delta fuses Single phase, all synchronous types and delay"D" yy"D" "D" setting ampacityof squirrel cage and Overcurrent allowable protection setting maximum ofcircuits circuitallowable breakers rating of the oftime-limited fuses and Type for motor [A] Reactor (Full voltage, Resistor and breaker breaker Breaker Circuit Circuit Squirrel cage and Synchronous


Fuses

Non-time delay Starting) (Autotransformer and Maximum Non-time 1 450 87.5 175 350 225 187.5 181.5 81.5 225 300 rating 200 250 300 169.0 175.0 75.0 69.0 150 125 150 175 200 225 150 175 125 200 150 175 107.5 105.0 102.5 110.0 112.5 115.0 117.5 120.0 122.5 allowable 400 250 102.5 350 105.0 162.5 125.0 137.5 150.0 107.5 110.0 112.5 115.0 117.5 131.5 120.0 122.5 156.5 144.0 25.0 37.5 56.5 44.0 50.0 100 110 125 90 of of overload fuses Fuses conductor Minimum fuses fuses Overload d.c. or wound rotor a.c. 300 31.5 62.5 Timedela Time devices Maximum protection for Star-Delta setting Overcurrent allowable Type protection for setting motor maximum of circuits circuit allowable breakers [A] rating of the oftime-limited fuses and delay"D" yy"D" "D" ~50 ampacltyof squirrel Single cage phase, and all synchronous types and Reactor Starting) (Full voltage, Resistor andcage Maximum breaker breaker Breaker Circuit Circuit Squirrel and Synchronous

Fuses

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).

Non-time (Autotransformer and delay Starting) 400 450 Maximum -Maximum Non-time Overlo::.ld protection forStar-Delta 225 250 300 250 250 500 500 600 200 206 219 225 238 231 244 194 250 263 200 194 206 213 219 225 231 244 238 250 263 200 225 175 rating allowable 350 450 400 600 500 275 275 250 313 313 300 288 288 300 300 300 213 fuses Fuses overload devices fuses Starting) conductor 300 350 Minimum 500 350 limedela lime fuses d.c. or Maximum wound rotor a.c. yy"D" "D" setting ofof ampacltyof squirrel cage and Single Overcurrent phase, allowable Type protection all synchronous types for setting motor and maximum ofcircuits circuitallowable breakers [A] rating of the oftime-limited fuses and delay"D" (Full Reactor voltage. Resistor and breaker breaker Breaker Circuit Circuit Squirrel cage and Synchronous


---Non-time -delay ----400425 '~ Non-time (Autotransformer Starting) and 500 600 500 600 Maximum -overload ratingFuses 625 625 600 325 350 '400 350336 400375'· 400400 500450 500475 500500 600 450 600 400 3 -325 363 375 400 425 450 475 500 63 450 300 350 400 575 500 550 600 600 conductor Maximum d.c. or Maximum wound rotor a.c. allowable Minimum 350 500 500 575 336 525 Fuses fuses fuses fuses Overload devices 550 Tlmedela Time protection for Star-Delta 5~5 setting ofof ampacltyof delay. ~OO yy''O" "0. "0" Overcurrent protection maximum rating fuses and squirrel cage and Single phas~, all synchronous types and Type for motor [A] allowable setting ofcircuits circuitallowable breakers of the oftime-limited (Full Reactor voltage, Starting) Resistor and breaker Breaker breaker Circuit Circuit

Squirrel cage and Synchronous

SECTION

12

HAZARDOUS LOCATIONS

12.1

SCOPE

(1) This Section applies to hazardous locations in which electrical equipment are subject to the conditions classified as follows:

and wiring

(a)

Class I locations in which flammable gases or vapours are or may be present in the air in quantities sufficient to produce explosive or ignitible mixtures;

(b)

Class II location which are hazardous because ofthe presence of combustible

or

electr.ically conductive dusts; and (c)

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.

12.2

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)

12.3

C22.1:1990

Canadian Electrical Code, Part 1, Safety Standard Installations, Sixteenth Edition.

for Electrical

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.

I

Division 2, comprising Class locations in which:

(b)

(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, bu.twhich may become hazardous as the r~sult of failure or abnormal operation of the ventilating equipment; or (iii) the IQcation is adjacent to a Class I, Division 1 location, from which a hazardous ~ncentration of gas~es 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 (1) Class

II locations shall be divided into two divisions as follows:

a) Division 1 comprising Class

IIlocations 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)".the 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

280

EBCS-10 1995


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 fibr~s or materials producing combustible flyings are handled, manufactured, or used. b) .Division 2, comprising Class III locations in which readily ignitible fibres other fhan those in process of maI}.ufactureare stored or handled. 12.4


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 atmosphericgI:oup 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 equivalent in hazard to hydrogen, such as manufactured gas), or propylene oxide;

ETHIOPIAN BUILDING CODE SifANDARD

EBCS-10 1995

281


c) Group C, comprising atmospheres containing acetaldehyde, cyclopropane, dlethyl .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; f) Group F, comprising atmospheres containing carbon black, coal or coke dust; g) Group G, comprising atmospheres containing 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 and II 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 tJ1arked 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 indicate the maximum external temperature Temperature

282

T6 T3A T4 T3C T5 T4A 100 200 85 T38 180 165 160 135 120 215 230 450 300 280 260 Max. Max. external external Temperature oode temperature temperature [0C] [0C]

EBCS-10 1995

.


SECTION 1

H

RDOUS LOCATIONS

(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

-

28O"C 28O"C 160"C 215°C

(4) Equipment approved for Class I, Division 2 only shall be so marked. (5) slectrical equipment approved for operation at ambient temperatures exceeding 40"C 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 roo~ or section will remain free from hazards.


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283


(2) Where a non-hazardous location within a building communicateS with a Class I, location, the locations shall be Division 2 location, a Class II location, or a Class

ill

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 iil 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. 12.5

CLASS I WCATION

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, instruments 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.

284

EBCS-10 1995



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 threaded 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 connection 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 at the 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 maximum wattage of lamps for which they are approved. (2) Boxes, box assemblies or fittings used for the support of lightiRg fixtures shall be approved for the purpose and for Class I locations.


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285


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 o(gases, vapours, or flames through the system from one portion of the electrical installation to another. 12.5.2.2


(1) Motors, generators, and other rotating electrical machines, in which are incorpor~ted

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 pr0v.ided with enclosures approved for the location. 12.6

CLASS II LOCATION

12.6.1

Installations in Class II, Division 1 Locations

12.6.1.1


(1) 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, conJroUers,circuit breakers and fuses (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 II locations. 12.6.1.3 Motors and generators (1) Motors, generators and other rotating electrical machines shall be approved for Class

n 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.


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,

(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 105mlong and extending downward with .the dust· tight enclosure.

12.6.1.5 Lightingfixtures (1) Fixtures for fixed and portable lighting shall be approved as complete assemblies for Class locations and shall be clearly marked to indicate the maximum wattage of lamps for which they are approved.

II

(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 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


(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 shail be installed and supported in a manner to avoid tensile stress at the cable glands.


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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 appro.ved 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-vapour and fluorescent lamps shall conform 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


(1) Transformers and capacitors shall conform to the requirement of 12.6.2.1 12.7.1.2

Switches, cntrollers, circuit beakers and fuses

(1) Switches, motor controllers, circuit breakers and fuses, including push buttons, relay~ and similar devices, shall be provided with tight enclosures designed to minimize entrance of fibres and flyings, and which shall: a) be equipped with telescoping or close fitting 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 electrical machinery 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 vicinityof 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 opemngs; 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


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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 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 designed to 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 Rormal conditions of use. (2) Lighting fixtures which may ~e exposed to phystcal 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-batterycharging 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.

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12.7.2

Installations in Class III, Division2 Locations

12.7.2.1


(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. 12.7.2.3

Switches, controllers, circuit breaker.t and fuses

(1) Switches, motor controllers, circuit breakers, and fuses shall conform to the requirement of 12.7.1:2. 12.7.2.4


(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 iI)Stalledin Class III locations.


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SECTION

13

FlAMMABLE UQUID DISPENSING AND SERVICE STATIONS, GARAGES, BULK STORAGE PlANTS, FINISIllNG PROCESSES AND AIRCRAFf HANGARS

13.1 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 selfpropelled 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. c) 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 storage plants where gasoline or other similar volatile flammable liquids are stored in tanks having an aggregate capacity of one-car-Ioad or more, and from which such products are distributed (usually by tank truck). e) Finishing processes where paints, lacquers or other flammable finishes are regularly 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.

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ETHIOPIAN BUILDING CODE STAN'DARD

SECTION 13: FLAMMABLE LIQUID DISPENSING AND OTHER FACILITIES

t) Aircraft hangars used for storage or servicing of aircraft in which gasoline jet fuels, or other volatile flammable liquids, or flammable gases, are used; but shall not include those locations used exclusivelyfor aircrafts that have never contained such liquids or gases, or which have been drained and properly purged. 13.2


(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)

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 d~penser enclosure upto 1.2m vertically above its base including the space below· the dispenser which may contain electrical wiring and equipment shall be e<;>nsideredto be Class I, Division 1 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) aoove shaU be considered to be a Class I, Division 1 location. (4) In an outside location, any area beyond the Class I, Division 1 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.Ommabove 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) Electrical wiring 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 1.5m 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) The area 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.

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(2) Where dispensers are supplied by rigid metal conduit, flexible fittings of the explosionproof 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 shallbe considered to be a Class I, Division 2 location. (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 locationwhich 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 50.0mmabove 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 Equipm~nt 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 makeand-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.

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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) Neas containing pumps, bleeders, withdrawal fittings, metres and similar 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 15m 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: i)

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


EBCS-10 1995

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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 level within 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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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 105m of vent opening and extending in all directions shall be considered a Class I, Division 1 location. d) The area between 105mand 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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(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

FINISlllNG 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.

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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 I}ot in operation, the space shall extend at least 105m 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~hinwhich 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 (lb) above, where adequate mechanical ventilation with effective interlocks is provided at floor level: a) the space within 900.0mm horizontally 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


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, ELECTRICAL INSTALLATION OF BUILDINGS

b) all space between a 900.0mm and 105mdistance 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 1.25mm 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 105m,the space behind this baffle shall be considered to be a nonhazardous 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 tr~nsparent or 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 or conduction from the source of illumination. (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:

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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 simultaneol,lsly;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 or 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 porta~le equipment, regardless of voltage, shall be bonded to earth in accordance with ,Part I of Section 7 of this Code.' 13.8

AIRCRAFf 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 ~ot 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 105m 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 level1.5m above the upper surface of wings and of engine enclosures.


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'ELECTRICAL 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 similar locations, may be classified as nonhazardous 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 compressed air. (4) Attachment plugs and socket outlets in hazardous locations shall be explosion-proof?r 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 (MineralInsulated) 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.

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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-andbreak 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.


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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 ele~trical systems of hospitals designated as essential electrical systems.

14.2

NORMATIVEREFERENCES

(l) The following references contain provisions which, through reference in this text, constitute provisions of the Ethiopian Building Code S~dard on Electrical Installation of Buildings: . a) C22.1:1990

Ganadian 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·

DEFI~ITIONS

(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.

appUed part

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EBCS-10 1995

the part or parts of medical electrical' equipment including the patient leads which come intentionally into contact 'Wi.,ththe patient to be examined or treated.


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.

critical care 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 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 system

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.


which the

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isolated system

an electrical distributi.on system in which no circui.tconductor 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 prqvision of diagnosis, therapy, or care.

patient care location

a zone in a patient care area which has been pre-selected for the accommodation of a patient bed, table, or other supporting mechanism, and for the accommodation of equipmentlnvolved in patient treatment, and which includes the space within the room 1.5m beyond the perimeter of the bed in its normal location and to within 203m of the floor.

patient car~ location bonding point

a common bus at a patient care location, that is bonded to earth, and that serves as a common point t6 which equipment and other bonding connections can be made by means of a group of-jacks.

permanently

equipment that is electrically connected to the supply be' means of connectors that can be accessed,

connected equipment

loosened or tightened only with the aid of a tool. total hazard index

the hazard index of a given isolated system with all appliances, including the line isolation monitor, connected.

vital branch

that portion of an essential electrical system in which the circuits require power restoration within 10.0s.

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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 circuitconductors 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.


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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 of 3-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-curr9nt-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, serv~ng 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 shallbe located: a) adjacent to the wash basin, and b) outside of any bathtub enclosure or shower stall.

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(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 spcket 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 care 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-Iocation bonding point is provided, it 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 equipmen.t 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 the requirements of Clause 14.4.3; and b) where supplied from an isolated system, be so identified.

t For definition of Class A earth-fault circuit interrupter, refer to Clause A.2, Annex A, Section 25.


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•


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*ing 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 pow~r system serves a single location, 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.2ohm, 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:

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i) ii)

a single anaesthetizing location; one or more patient care locations in a single room; or

iii)

a maximum of two patient care locations 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 ftxture, raceway, box or cabinet occupied by other wiring except where necessary as in:


EBCS-10 1995

315'

ELECTRICAL

INSTALLATION

OF BUILDINGS

a) transfer switches; and b) emergency lighting fixtures supplied from two sources. 14.8

TRANSFER SWITCHES

(1) All transfer switches shall be acceptable to the supply authority. (2) Automatic transfer switches used in essential electrical systems shall: a) be electrically operated and mechanically held; and b) include means for safe manual operation. (3) Manual transfer switches shall conform to the following: 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 c.pntrol shall include a means for safe manual mechanical operation. c) Reliable mechanical interlocking (and, fn 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 tlwitch. d) A manual transfer switch shall include a readily visible mechanical indicator showing the switch position. (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 and damage.

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EBCS-10

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ETHIOPIAN



(2) The prime mover of the generating set, as specified in (1) above, shall be capable of operating independently of supplies of water and fuel from public utilities. (3) A fuel supply sufficient to operate the prime mover under full load for at least 24.0hrs shall be stored on the site.


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SECTION

INSTALlATION OF liGHTING EQUIPMENf

15.1

SCOPE

(1) This Section applies to installation of interior and exterior lighting equipment.

15.2

NORMATIVEREFERENCES

(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 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:

British Standard, Lighting Columns Parts 1, 2, 4, 5, 6, and 9.

15.3

INTERIOR LIGlITING 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.

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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 s·afety, 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 of nominal system 380.0V. Where 380.0V line-to-line system is used, the control switch shall be of double-pole type and the luminaire shall be earthed.

Note:

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 b~ connected to a branch circuit protected by overC4rrent devices rated or set at not more than 20.0A. (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: ~

20.0A 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.


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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.

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(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, it'is admissible for the switch to be placed adjacent to the normal 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 .::omprising 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 st~irway 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 parts (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 Supports (1) Every luminaire, lampholder and rosette shall be securely supported. (2) Where a luminaire weighs more than 30.0N 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 box of 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 600Cj and the mass suspended shall not exceed 30.0N.


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(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. (5) Where a luminaire weights more than lOa. ON,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 Recessed luminaries (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 90oe. (3) Recessed luminaries shall not b,e used when blanketed with thermal insulation unless the luminaries are marked and approved for this use. 15.3.3.5

Minimum height of luminaries

(1) Where a rigid luminaire or 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.

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15.3.3.7 Luminaire as a raceway (1) Branch circuit conductors run through a luminaire shall be contained in a raceway which is an integral part of the luminaire except that the conductor of a 2-wire, 3-wire, or 4-wire branch circuit supplying the luminaire may be carried through: a) an installation of luminaries approved and marked for end-to-end assembly to form a continuous channel; or b) luminaries which are connected together by acceptable wiring methods. (2) Ballasts located within luminaries shall be deemed to be sources of heat and' the conductors supplying the l\lminaries shall: a) have a temperature rating not less than 90°C; b) be of type listed in: i) Section 4, Annex :S, 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 2.5mm2 and do not extend " beyond the luminaries through raceway more than 2.0m long. 15.3.4

Wiring of Lighting Equipment

15.3.4.1

Wiring of luminaries

(1) AIl electrical wiring on or within -aluminaire, -beside ensuring its electrical safety, shall: a) be neatly arranged without excess wiring; b) be not exposed to 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 arm or stem. 15.3.4.2

Colour coding

(1) Notwithstanding the requirements of Section 4 with regard to the colours used for identifying conductors, a continuous-coloured tracer in the braid ~f individual braided conductor shall be permitted for the supply conductors of a luminaire.


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I'"

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 area, having insulation suitable for voltage and temperatnre to which the conductors may be subjected. 15.3.4.4 Conductor on movable parts

(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 do.es 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 lumina ire 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 1.0mm2 copper run in a factory-installed raceway or, if raceway is provided but not factory assembled, smaller than 2.5mm2; b) extend at least 1S0.0mm 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

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opening shall be not less than 200.0mm x 200.0mm and the outlet box shall be mounted within 350.0mm of the opening. (5) A supply connection box forming part of an approved luminaire assembly shall be accessible, and if access is through the opening for mounting the luminaire, the following requirements shall be met: a) The electrical components of the luminaire shall be capable of being extracted through the opening for service. b) The cover of the supply connection box shall be capable of being removed by hand tool held below ceiling. (6) Branch-circuit conductors shall not pass through the supply connection box forming part of an approved luminaire assembly unless the luminaire is approved and marked for the purpose. 15.3.4.7 Ceiling outlet box wiring (1) Branch-circuit conductors having insulation suitable for 90°C shall be used for the wiring of all ceiling outlet boxes on which a luminaire is, or may be, mounted; and the ampacity of 90°C wire shall be limited to the ampacity of 60°C wire. 15.3.4.8 Wiring of show-window luminaries (1) Where show-window luminaries are closely spaced, they shall be permitted to be connected to c;. conductor suitable for the purpose which is listed in Annex B of Section 4 with a temperature rating of not less than 125°C. (2) The connection of show-window luminaries to the circuit conductors shall be in a junction box; and the box shall be maintained at a sufficient distance from the luminaire to ensure that the circuit conductors are not subjected to temperature in excess of their rating.


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..


15.3.5

Earth"ing of Lighting Equipment

15.3.5.1 General (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 lampholders are connected to a source of supply having an earthed neutral conductor, the outer or screwed contact shall be connected to that· conducfor. (2) Where lampho"lders in (1) above are used in circuits having neither pole connected with earth or in any damp situation in which they can readily be touched by a person in contact with or standing on earthed metal, they shall be provided with a protective shield of insulating material or shall be placed or safeguarded so that neither the lamp cap nor the• oute,r or screwed contact of the lampholder can inadverntly be touched when the l~mp cap is engaged with the contact. 15.3.6

Electric-Discharge Lighting Systems Operating at 1000.0V or Less

15.3.6.1

Transformer

(1) OiHilled transformers shall not be used. 15.3.6.2

Thermal protection

(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 equipment (1) Reactors, capacitors, resistors, and other auxiliary equipment shall be: a) enclosed within the liminaire, b) enclosed within an accessible, permanently installed, metal cabinet where remote from the luminaire, or c) acceptable for use without an additional enclosure.

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SECTION 15: INSTALLATION OF LIGHTING EQUIPMENT . -

(2) The metaJ cabinet, if not part of the luminaire, shall be installed as close as possible to the luminaire. (3) Where display cases are not permanently installed, no part of a secondary circuit shall be included in more than one case.

15;~.6.4 Control (1) The luminaries. and lamp installations shall be CQp.trolledby a switch, circuit breaker, or contact.or. (2) Where a switch is used as in (1) above, it shall:

a) have a current rating of not less than twi~ the C\lfrent 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 LIGHTING 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 sh?-llbe the major concern and the fire hazard of the minor or of secondary nature. 15.4.1.2 Ballast protection

(1) Luminaire which employ fluorescent lamps shall hwe thermally protected ballasts except where the ballasts are of the simple reactance type. 15.4.1.3 Overcurrent 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.


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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 are 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) Suitable corrosion-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 miner~l-insulated cable, or up the centre of steel, aluminium, ot hallow concrete poles; b) The conductors and live parts are kept at least 1.0m 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 jnjury 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 oflocations 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 weatherproof enclosure. Note:

The panelboard may be omitted where there are two branch circuits on a 230/380.0Y circuits with a common neutral lineand where there are three branch circuits on a 230/380.0Y, 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'.


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(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 the 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)

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-


15.4.3

Exposed Wiring for Permanent Outdol.. Lighting

15.4.3.1

General

(l) Clause 15.4.3 shall apply to exposed wiring for permanent outdoor lighting other than floodlighting where the circuits are run between buildiilgs, between poles, or between buildings and poles. 15.4.3.2

C7olUiuctors

(1) Conductors shall be stranded copper, not less than 2.5m2, 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 15.4.3.3.1

Use of insulators 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. 15.4~3.3.2Type of insulator (1) Insulators at the ends of runs shall be of the strain type unless the conductors are supported by messenger cables. 15.4.3.3.3 Split knobs

(1) Split knobs shall not be used.


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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 t9 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.

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EBCS-10 1995



15.4.3.8

Use of messenger cables

(1) Messenger cables: a) .shall be used to support the conductors: i) if lampholders 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.


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333

ANNEX A (NORMATIVE)

LIGHTING COLUMNS

A.i

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.

nominal 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.i.

Figure A.i Nominal height

334

EBCS",,101995



post-top columna

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 lanterhs) by means of one or more brackets which are integral with, or demou'ntable 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. w

The of the is not ,in this

shape bracket speCified standard

'. 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.


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lantern fixing angle door opening

angle between the axis of the lantern fixing and the horizontal. opening in a column for access to electrical equipment. 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

J!Y'~ ,,',---,,'

)

Figure A.3 Planting.depth

base plate

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

Figure A.4 Base plate

336

EBCS-10 1995 ,



flange plate

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 AS.

)

.~.

Flange plate

Figure A.5 Flange plate A.2

DIMENSIONS AND TOLERANCE

A.2.t

Requirements

The dimensional requirements are specified except that the connection dimensions in Clause A2.7 represent a recommended choice.


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A.2.2 Post top columns, main dimensions (in meters)

For to.lerances for dimensions and shape see clause 8 Nominal

---...----_. -------.---20 ---.----_ 18 15 __ -----h... 46 12 85 huillht ,_.~_.

__

••

_ •••••

_

On_

••••••

___ .•...

.

3 10

For dimensions for door openings and cable entry slots see clause A

!

+ ..--

i. ·1

·01 Z-..r

W$.I 1

2,~

-., +.

J~

r'.... :·'

For flange plate

For base plate see clause A..?.5 Type A1

Type A2

For column foundation see clausE' A

·338

EBCS-to 1995

see clause '

Al.6

Type A3

2.5

ETHIOPIAN BUILorNGCODE

STANDARD


A.2.3 Columns with brackets, main dimensions (in meters)

w Connection dimensions (see clause Lantern fixing angle 5° or 15°

AZ.?)

'\

The shape of the bracket Is not specified in this standard

)

For tolerances

0'----0/

for dimensions

and shape. see clause Nomine' h helohl 52 615 1B to18

A ~. 8 Projection

wll

0.75 1,25 2

3 For dimensions

for door

opening' and cable entry SlolS see clause A;Z.4

m~ Typo B1 For column

11

For flange plate see clousa AZ.t:

For clause base plate see A1.5

~

Type B2 foundation

see clause

Type B3

A2.5

II is recommonded Ihal w venerally should be equello. or less Ihln.1-


EBCS-10 1995

339

l

a


A.2.4 Door openings and cable entry slots (dimensions in millimetres)

--~

.'\

~

\

---

/"

//

),

~I I

• .._---500 600 -._-~--400 - 900') a

b

130 1'00 120 85 100 115 75 1301) 951) 1301)

500 300 600 200 6801) 6801)

@J I

F''Jwe. A2·3 Position

of door4)

and cable entry slot

-.,50

aa 1.01 Fl! -

I~

........ -9 -:~T II

'>_,

aUl

.-

1=lt'H~ A2."" Dimensions

of cutout

1) 2) 3)

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 300mm; no maximum is specified.

4)

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


SECTION 15: INSTALLATION OF L' 3HTING EQUIPMENT

A.2.S Column foundation, planting depth and base plate (din

Nominal

-- 10 18 15 12

300

X

6 haight mh 8 20

<5

.sians in rnillirnetres)

--

1700 2000 1000 600 1500 1200 1500 1000 1200 1500 1200 e1) 1800 1000 300 2500 800 Planting dapth

--

300

or 400

x

400

+

.~

t

Figure

A2.5a

Figure

1) 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.


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341


A.2.6

Flange plate (dimensions in millimetres)

j~

t'

\ /

, I

.~

II

A 7.:-- 7

gure

t.J1

!tl

) /

c: I

II L... ' -'J figure

A2.B

d2

I

Ii

m

" 12 <20

h

500

<

300 400 sll 300 200 d,1) M18 M24 400 8 c10 a260 M27 ,20

r

min. 400 ,I

!

5

M27

M18 d,l1

33 d2 400 30 22 500 700

,11

min.

M24

1) These dimensions shall be checked by calculation.

342

EBCS-10 1995


SECTION 15: INSTALLATION OF LIGHTING EQUiPMENT

A2.7

Connection Dimensions for Lanterns (in millimetres)l)

~l Fiuuro

A 2.',1

-.---

-;t

Figure

A2·~

76

70 130 250 '1

dlJ1

102 /tlO

(2 )

b

Post top !;.oterns

42 d2J1

}

60

,

250

--

100 100 '2

Figure

Figurll

Sidtl entry

AZ.IOb lantorns

r i {,! +

'x

cu(

..

-l:::

••

j

~"I\II

•.• E

.

Lt

~\'\ \."I ~I I\ .

\ 1) 2) 3)

\ !

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.


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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 Marm 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 Intrusion, Parts 1 and 2.

d) ,Euro Standard, En 54:1976

Component of the Automatic Fire Alarm Systems, Parts 1 and 5.

16.3

and

DEFINITIONS

(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

this be of smouldering sounders

devices

generated

or open-flame

in which electric

by fire, whether

type.

signals are converted

into sound

signals. lantern-light

a glazed construction

standing

above the surface

of a roof,

designed to admit light to the space below. alerting facility

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 smoke detector

a detector which respond to an increase in temperature.

. 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

fire alarm system

the entirety of the equipment and parts, matched for correct interaction, used in a fire alarm system.

alarm box cdntrol room

a facility from which the necessary fire fighting measures can be initiated at all time.


forces.

EBCS-10 1995

345


false alarm

a fire alann signal' caused by technical malfunctions

in the fire

alann system (alann resulting from disturbance) or spurious alanns resulting from the fire detector being "mislead".

non-automatic (manual) fire alarm devices

alarm devices which can be used to initiate the fire alann signals manually.

16.4

DESIGN CONSIDERATION

16.4.1 General 16.4.1.1

Design

(1) Fire alann systems shall be designed so that: a) the earliest possible definite warning of fire (i.e., avoiding false alann) is given to all personnel immediately concerned; b) it is capable of indicating the locality of the origin of the fire alann 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 alann 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

Alarm signals

(1) The audible and visual alann signals shall be used solely for the fire alann purpose, and these signals shall not reset automatically.

16.4.1.4

Location of the alarm control and indicating panel

(1) The fire alann 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 ma.chinery, 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 Jhere 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 be 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 alatm. To meet this requirement, suitable zones should be defmed 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.

Note:

16.4.3

Manual Call Points

16.4.3.1

General

(1) A manual call point shall be operated by a spring-loaded "non-alarm"

switch w~ich is held in

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

"1li

:

Construction and requirements

(1) 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 likely 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 co loured "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'ofthe 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

EBCS-10 1995



including the word "FIRE" on case, or by a suitably inscribed plate behind the glass cover; and

f) incorporate means whereby satisfactory operation may be readily and individually tested; e.g. by opening the front by means of a special key.

16.4.3.3

Stricker

(1) A striker shall be provided adjacent to the call point to facilitate breaking the glass.

16.4.3.4

Placement

(1) Manual call points shall be: a) so located that no person need travel more than 30.0m from any position within the premises in order to give fire alarm; . b) located on the exit routes and, in particular, on the floor landing of staircases and on exits to the street; and\~ c) fixed at a height of

104m

above the floor at easily. accessible, well illuminated and

conspicuous positions free from obstruction.

16.4.3.5

Manual call in automatic alarm

(1) Where manual call points are incorporated in an automatic fire alarm system, they shall be· included in such a way that the operation qf anyone of them produces the same effects as though fire had been detected by a fire detector in the same zone.

16.4.4

Selection of Fire Detectors

16.4.4.1

General

(1) When selecting the type of detectors, the probable development of fire in the incipient stage, the room height, the ambient conditions and all sources of spurious alarms in the areas to be monitored shall be taken into consideration. Note:

The task of fire detectors is to detect a fire wherever possible in its incipient stage and signal this automatically to an emergency service.


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349

ELECTRICAL INSTALLAT1ON OF BUILDlNGS

16.4.4.2

Detector types

(1) If development of a smoldeJ;ing 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 of smoke), 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 )'oom 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 ar~~ 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:

350

i)

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. ii) Voids not more than 800.0mm in height need not necessarily have independent monitoring. Hi) 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

(1) Lantern lights shall be monitored by detectors.

16.4.5.6

Special monitoring

(l) 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

(1) 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 l50.0mm below the ceiling or the underside of the roof.


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Table 16.1 Suitability of d'etectors and room height Cat... detectors w Cat. W W RW W RW R 1 R W R R 2 W RRR detector Cat. 3

Flame Heat detectors

Room height

R " Suitable

w-= Unsuitable

I

16.4.6.2 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 Spacing limits for sitting detectors 15.0 10.0 In 3.5 7.5 corridors In corri.dors Maximumpartitions (horizontal) Maximum apart between (horizontal) centers dlatance [m] or dividing [m] distance In general from any outside walls, separating walls In general

• In special buildings such as churcheli, mosques, museums and castles, it may be that detectors can only be arranged at a great height unper 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-tO 1995



16.4.6.3

Ceiling

(1) Where ceilings are crossed by beams, girders or other structural features having a depth of ·500.0mm or more, at least one detector shall be installed in each "pocket" fonned between such features, and these detectors shall not be less than 500.0mm from any beam, guider or wall.

16.4.6.4

Single truss and north- light roofs

(1) One row of detectors 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

Floo,' openings

(1) Detectors shall be so sited that at least one on each floor is suitably placed within 105m 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-tern perature- '. type detectors shall be used in such location. Note:

Such locations are liable to rapid temperature variations due to combin/ltion of solar and internal heating and, thus, ftxed-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 nonnal operation are likely, fixed-temperature detectors shall be used. (2) The static response temperature of the detector section shall lie between lOoe and 35°C abov.e 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 fixeQ.-temperature-type shall be used. Note:

Vibration coinciding with rising, although not dangerously rising, temperature could induce false alanns from other types.

ETHIOPIAN BUILD1NG CODE STANDARD

EBCS-10 1995353


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

General

(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.Omm 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:

Wann air naturally collec~

under ceiling and in the apices of pitched roofs .. In some circumstances,

this

wann 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



16.4.10.2

Audibility of general alarm

(1)" Alarm sounders shall satisfy the following requinnents: a) Their type, number and location shall be such that the alarm is distinct from the background noise in every part of the premises. b) 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 any circuit other than those with which the silencing switch is associated. 16.4.10.5

Two-stage ala,.",

(1) Where it is desired to distinguish between an alert and an evacuate signal, a two-stage alann shall be used in which the first type of signal indicates an alert and the second type indicates a need to evacuate the locality.


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355


16.4.10.6 Visual alarm signals (1) 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~address. equipment is used in stead of co~ntional ens.ured that:

sounders, it shall be

a) alarm of fire is automatically transmitted over the public addr~ss 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 broadcastby

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 shaH comply with the requirements of this Section.

16.5

CABLESANDWIRING

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.

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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) 1.5mm2 for individual cables pulled into raceway; b) O.8mm2 for individual cables laid into raceway; c) O.8mm2 for an integral assembly of two or more cables; d) O.5mm2 for 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 (I) above, cables smaller than 2.5mm2 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 bt;~. a) installed in a Q1etal raceway of the totally enclosed type; b) incorporated in cable, having metal armQur or sheath; c) installed in rigid non-metallic conduit where embedded in at least 50.0mm of mansonary or poured concrete, or installed underground.

16.5.2.2

Conductor in building of 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.


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16.5.2.3

Segregation

(1) 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) the source of supply, b) a signal, c) an ancillary device, d) 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 (1) 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

(1) All conductors contained in the same rl},cewayor cable shall be insulated for the highest voltage in the raceway or cable.

16.5.2.6 Avoidance of flue-like opening (1) In order to reduce the likelihood of damage to fire-alarm cables by fire, main fire alann wiring shall avoid lift wells, staircase, and other flue-like opening.

16.5.2.7

Disruptive electrical influences

(1) 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

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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 powt:ring fire alarm systems provided that a second similar battery in operational condition is held in reserve at all times.


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359


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 bperation of the system and the altering facilities is guaranteed; and b) also be able to supply the trickle charge current 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 utilizati0n 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 co loured 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 ampacity in 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 t~tally enclosed type; b) incorporated in metal raceway of the totally enclosed type; or c) incorporated in a cable, having a metal armour 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


(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 circuit protection

(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 shaU not require overload or overheating protection and shall be permitted to be protected by the motor branch-circuit

16.8.4.4

over-current device(s).

Earth-/ault circuit interrupter

(1) 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

:

1 st digit

- detector and alarm device group

2nd digit - detector or alarm device number in the detector and alarm device group FAP

:

Fire alarm control and indicating panel

TS

:

Transmission unit for fire alarm signals

'"

."

~.

'" ~, .. on 'M '"V, ~I VI ,"o...t'8' '8' '8" I~/////~ '8' ...'H1i' ,..... H g>---'ij' 'if

""

l~ r:..

,

Figure A.l Exampl.e - Automatic fire alarm system II"joIN'

'" In'''"

'"

lilT •••"

1Il

Figure A.2 Example device

Automatic fire alarm systems with non-automatic fire alarm


EBCS-10 1995

363

0

ELECTRICAL !NSTALLATION OF BUILDINGS

4/1

)111

f, ~14 :i/lS <'>

(j.il

I

ll/ll

Jl4

liS 2110

Jl12·

i.

r

.

JIM

III

..,ll~

Jll

f,

l/lIII,

1I1

RIO.

. Ill'

1319

,qlG 2/1

Hall

M~

IIG

1/1

1/4

.

III

III

II?

'II

,

IIIUO

Block circuit

,I

, In 0 ~"IUMn. '''fI'cIt IIwll

'01{1

diagram

BMZ 1/10

-

-

-

~

11.".101 'II"

___ -0 t::t

Ilu,n MMII,,,., 1111"' 102 - IU4 IMAt w.lIt

)IlL)

-

1"1 ~I

,---

-

-

-«£?

lI.n

(1l1l.lIn

Rus.

--~----: Fiu O'~'f1ftl~.~ (FWI

uE:

'lull,1 Pil'" IIPTI IUI.I.,nlll"dt

hhln. COM'Clio" ISA

Figure A.3 Installation plant of a fire alarm system with block circuit diagram

364

EBCS-10 1995


ANNEX

B (INFORMATIVE) UIT DESIGN

B.l MANUAL ~~D AUTOMATIC CAIJL POINT CIRCUITS B.1.1

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 thl:!n 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, solidstate 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.1.2

Circuit I _ Open circu~

o

.

0 supply

Figure B.I Open circuit

Alarm-sensing

unit

1 It Open Circuit


EBCS-10 1995

Call Point

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.1.3 Circuit 2 -

Closed circuit

Alarm-Sensing

Unit

supply

o Closed

circuit

call point

Figure B. 2 Closed circuit Current is n?rmally flowing through the cond~ctors 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

i!1terrupts the current to the alarm-sensing unit, initiating an

alarm signal.

366

EBCS-10 1995


SECTION 16: FIRE ALARM SYSTEM AND FIRE PUMPS -----------------.--------------------.------------------------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 Sensing Unit(alarm) '"

Limiting resistor.

supply

O---------l

Low-current ~Open sensing unit (fault)

circuit call point

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.

/

/


EBCS-10 1995

367

B.l.S

Circuit -I -

Combination open and closed circuits, Type B Medium-current

Open circuit

Sensing unit (al~

Supply

1

High-current

sensing

/ unit (fault)

~

O----------~LoW_o"rr.n''.n'~"l unit (fault)

---~-

'_._M__ '

call point

0

o

Open circuit

-~~;;i~~~

call point

.

Limiting resistor

,nin, r..i:::: -

.

_

Figure B.4 Combination open and closed circuits, 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 highcurrent 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.

368

EBCS-10 1995



B.2

ADV ANTAGESANDDISADV

b.2.!

Circuit 1

ANTAGESOFV

ARIOUSCALLPOINT

CIRCUITS

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 i)

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.

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-10 1995

369


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) ii)

Current is consumed on stand-by. 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.

Hi) A short-circuit between conductors will produce afault s~gnal, 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.

310

EBGS-10 1995


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 are: a) incandescent lamps, b) fluorescent lamps, c) high-voltage luminous discharge tubes including neon tubes, and d) high intensity discharge lamps. Note:

The word "sign", when used throughout

17.2

NORMATI\%REFERENCES

this Section, includes those of the through-wall

type.

(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.

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 Installation, Sixteenth Edition

1, Safety Standard

for Electrical


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:


EBCS-10 1995

371


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.

372

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 2.2m 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 (1) 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 (1) Conductors

for sign and outlying lighting shall be installed in accordance with the

requirement of Section 8. 17.3.10 Fuseholders and Flashers (1) Fuseholder, flashers, etc. shall be enclosed in metal and shall-be accessible without the necessity of removing obstructions or, otherwise, dismantling the sign.

17.4

HIGH-VOLTAGE LUMINOUS DISCHARGE TUBE SIGNS AND OUTLINE LIGHTING

17.4.1 Enclosure 17.4.1.1

General

(1) 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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373


17.4.1.2

Construction

(1) The enclosure shall be cC'nstructed to prevent the emission of flames or any burning or ignited material.

17.4.1.3

Ventilation

(1) Openings for ventilation shall be arranged to comply with the requirement of 17.4.1.2 and shall at least be 100.0mm from live parts.

17.4.1.4

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.

17.4.2 Protection of Uninsulated Part (1) Doors or covers accessible to the general public and which give access to uninsulated

parts

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. 17.4.05

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.

.

f ••••.

374

EBCS-10 1995


•

SECTION 17: SIGNS AND OUTLINE LIGHTING

17.4.3.2 .

(I)

Open core-and-coil type transformers shall only be used indoor.

17.4.3.3 (I)

Open core-and-coil type transformer

Transformers used outdoors

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


(1) 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 (I)

Conductor installation

High-voltage conductors shall be installed in: a) transformer enclosure, b) sign enclosure, c) flexible metal conduit, d) rigid conduit, or e) other acceptable type of raceways except for surface raceways.


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375

ELECTRICAL INSTALLATION OF BUILDiNGS

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 luminous-tube-sign type cables.

17.4.4.5

installed inside metal sign enclosures

shall be of the

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


18

SECTION

LIFTS, ESCALATORS AND SIMILAR EQUIPMENT

18.1

SCOPE

(1) 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


(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.

18.3

a) C 22.1: 1990

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

b) NFPA 70/NEC:1986

National Firr Protection Association/American Electrical Code, 1987 Edition.

National

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) 380.0Y for operating control and signalling circuits and related equipment, including door operator motors. b) 750.0Y for driving motors, machine brakes, and motor-generator sets.


EBCS-10 1995

377


Exemption:

Higher voltages shall be pennitted

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 flame-retardant and suitable for temperature of not less than 200°C.

18.4.1.2

riser shall be

Travelling cables

(1) Travdling 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

Insulation rating

(I) 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


SECTION 18: LIFTS, ESCALATORS AND SIMILAR EQUIPMENT

a) for lighting circuits, 1.5mm2; and b) for operating control and signalling circuits, 0.5mm2•

18.4.3 Motor Circuit Conductors (l) Conductors supplying lifts, dumbwaiters, escalator, or moving walk motors shall have an ampacity of:

18.5

(a)

if supplying single motor, not less than 150% of the motor full-load current rating.

(b)

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 (l)

In hoistway, machine rooms, and escalator wellways

Conductors located in hoistway, machine rooms and escalator well-ways, except travelling

cables, shall be installe~ 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 of damage to the sheath.

18.5.1.2

(In cars

cable may be used if located so that there is no liability

(l) 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 same 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 if located 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 600.0Y 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 pennitted 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 th~ 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 platfonn 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;


EBCS-10 1995

381


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


SECTION 18: LIFTS, ESCALATORS AND 'SIMILAR EQUIPMENT

(3) Where there is more than one driving machine in a machine room, disconnecting means shall be number-marked control.

to correspond to the number-mark of the driving machine which they

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 (1) 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. driven by polyphase alternating current shall be provided with a means to prevent starting of the 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 circuits shall be protected against overcurrent in accordance with the requirements of the relevant Clauses of Section 9.


EBCS-10 1995

383


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. motors shall be protected Section 11.

against overcurrent

in accordance

with applicable

Such

Clauses of

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

18.10.2

in (1) above shall be secured against unauthorized access.

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 EARTIllNG 18.11.1

Metal Raceway Attached to Cars

(1) 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 (1) 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.


____

EBCS-10 1995

~~~~~~~===~~~~========J.4

385

l ELECTRICAL INSTALLATION OF BUILDINGS

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 requirements of a 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, the disconnecting 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


SECTION

18:

LIFTS, ESCALATORS

AND'SIMILAR

EQUIPMENT

18.14.1.2 Illumination level (I) IHumination shall be not less than

lOO.O/x

at floor level.

18.14.1..3 Lighting switch (1) 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 .othersocket outlets shall be installed in the machine room.

18.14.2

Hoist ·Pits

18.14.2.1 Luminaire (I) -OneQf mote p.ennaAent luminaire equipped with a guar.d of metal, safety glass or suitable plastic matedal shaH tbeprovided in aU pits. t8.14.2.2

Illumination level

The luminaires shall provide an illuminations level of at least

lOO.O/x

at the pit floor.

18.14.2.3 Lighting switch

(I)

A Hghtswitchshall access door.

'be 'provided ,and shall be located so as lobe

accessible from the pit

18.14.2.4 Socket outlet (1) At least one twin socket outlet connected to a 1'6:0A branch circuit supplying no other socket outlet shall ,be installed in .each ;pit.

EIHUOPIAN

,BUILDING ,CODE STANDARD

EBCS-10

1995387

\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 Installation, Sixteenth Edition.

for Electrical

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)

installed within every switchboard enclosure,

(b)

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

(c)

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

ELECTl1lCALINSfALtAflON ,~,

,

'_'_~""

__"'_<"

•••

.. "._

.. _.

H

__ .•"._,

OF BUILDINGS _.

om.

~_.

•••

_

19.4.3 Dimmers (1) Dimmers shall be connected so as to' be dead when their respective circuit switches are open. (2) Dimmers which do Mt open the circuit may be connected in earthed neutral conductor. (3) The tenninals of dimmers shall be enclosed. (4) Dimmer faceplates shall be llf1'anged so thllta~cidental contact cannot readily be made with the faceplate ContactS.

19.4.4 Control ofStllgeand

Gallery Pockets

(1) Stage and galiery pockets shall be ~ontrolled from the switchboard. 19.4.5 Conductors (1)

Stage switchboards equipped with re's'istlve~'or transfortfied~typ'€ dimmer :switches ,shaH be

wired witheonductotshaving insulatio'nsuhable for the temperature generated therein; put in no case shaH the design temperature be less than f2sot. (2) Th'e conductors in (1) above shall have anampadty

of hot less than that of the switch or

overcurtent device to which they are connected. (3) Holes in the metal enclosure through which conductors pass shaH be bushed. (4) The strands of the conductor shall be soldered together hefore they are fastened under!a clamp or binding screw. (5) Where a conductor

of

lO.Omm? or

'Of

a larger size is connected toa terminal:

-a) it 'shallbe .soldered into a lug;, or b)a

soiderlesscbhnectot

.shaH'be used·.

etHloP1AN

13UILDING CODE 'STANDARD

SECTION 19: THEATRE INSTALlATION

19.5

PORT ABLE SWITCHBOARD

19.5.1 Construction

of Portabl~

ON STAGE

Switc"bo~rds

(1) portable switchboards shall be pla~ed within ~nclosure of substanti!ll construction; but they may be arranged so that the enclosure is open during operation. (2) Then~ shall be no live parts exposed wit.hin the, enclosure. ~x.cept thos~.on.dimmer faqeplates. 19.5.2 Supply for Portable

SwjtcbbOjlrd

(1) Portable switchboards shall be supplied by means of flexible cord elf cable. of e.xtra"bard usage type tenninating fused master switch.

within the switchboard enclps\lre in an e~terncllly operated, en~loseQ~

(2) The master switch in (1) llbove shall be arrMged so as tel cyt off qurr~l1t from all apparatus. within the enclos\lre except the pilot light. (3) The flexible cord or cable shall have sufficient ~apcity the switchboard.

to carry the total load, CijITent of

(4) The ampere-rating of the fuses of the m!lster switch shall not be greater than tile tQtlllloaQ current of the swltehboCU'd.

19.6

FIXED STAGE EQUIPMENT

19.6.1 FoptHght$ (1) Where footlights are wired in rigid metal conduit or electrical me.taJli9 tubing, every lampholder shall b~ instllUed in an indivig)Jal outlet box. (2) Where footlights are not wired in rigid metal conduit or electrical met/dUe tubing, the wiring shall be installed in a metlll trough. 19.6.2 Metalwork (1) The metalwork for footlights, borders, pro!!ceniu!ll sidelights, and strips shall not be les'" than Q.8mm thick.


EBC$-1 0

199~

391


(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 (1) 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 • provided'to

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 (1) 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



19.6~10Pendant Lights Rated More Than 100.0W (1) Where. a pendent lighting device contains a lamp or group of lamps of more than IOO.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.

19.6.11Cables 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

ELECTRICAl- INSTALLATION OF BUILDINGS

(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 6.0mm2 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

PORT ABLE 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 extrahard-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.


EBCS-10 1995

395

SECTION

20

EMERGENCY SYSTEMS, UNIT EQUIPMENT, AND EXIT SIGNS

20.1

SCOPE

(1) 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 ~upply power, where required by the authority having jurisdiction, and b) thewiring of exit signs.

20.2

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) C22.1: 1990

20.3

Canadian Electrical Code, Part 1, Safety Standard Installations, Sixteenth Edition.

for Electrical

GENERAL

20.3.1 Capacity (1) 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 td 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 req~ired 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 EmlIDING CODE STANDARD

EBCS-10 1995

397


20.4

EMERGENCY SYSTEMS

20.4.1 Supply (1) 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) ~rranged 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 (1) 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

(1) 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



20.4.4.2 Wiring (1) 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 wiU: i) sound, thus indicating the necessity of restoring the s.ilencing 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 Voltagedrop (1) The voltage drop in the wiring feeding lamps mounted remote from the 'currenfsupply shaH not exceed 5% of the applied voltage.

20.S

UNIT EQUIPMENT

20.S.1Mounting (1) Each unit equipment shall be mounted with the bottom of enclosure not'less

than 2.0m

above the floor wherever practicable. Note:

Unit equipment for 'emergency lighting i)

is defined ,as an -item of equipment that:

is intended to provide automatically , in response to ,afailure of a power supply 'to which it is connected, 'specified ,light output and a specified amount of power for illumination purposes, for a specified period of time, but in any case not :Iess than 30.0min;

ii) comptises,in

'a unit construction, a storage battery , 'charging means to maintain the battery in a charged

condition automatically,

lamps, ·ot output terminals to which specifically listed lamps may be connected,

means to energize the lamps when the normal power supply fails and to de-energize the lamps when the normal power supply is reStored, and means to indicate and test the operating equipment.

ETHIOPIAN BUilDING

CODE STANDARD

iEBCS..:10

conditions

1'995

of the

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 1.5m.from 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 acthlated 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.

20.5.2.6

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



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

SECfION

21

MOTION PICfURE STUDIOS, PROJECTION ROOMS, FILM EXCHANGES AND FACTORIES

21J.

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 following r,eferencescontain provisions which, through reference in this text, constitute • provisions ,ofthe Ethiopian Building Code Standard conElectrical Installat,ionof Buildings: a) C22.1.:199(:)


b) NFPA70/NEC:1986

National Fire Pwtection Association / American National Electrical Code, 1987 Edition

21.3

GENERAL

21-.3.1 Wir.ing Method

(1) The wiring method, unless specifiedofherwise in subclause·of'this Section, 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-1G1995


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 c) provided 21.4

or metal sheathed

procelain,

and

with a guard hook and handle.

VIEWING, CUTTING AND PATCHING TABLE FIXTURE

(1) All lighting fixtures, except lamps forming an integral part of table equipment, of the totally-enclosed gasketted type. 21.5

shall be

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 shall be installed.

(2) .No electrical equipment in film vaults.

plugs

other than that necessary for fixed lighting shall be installed

21.5.2 Wiring Method in Film Vaults (1) The wiring method in film-vault shall be rigid-conduit with threaded

or mineral-insulated

cable only,

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 approved

shall be sealed off near the switch enclosure

with a fitting and compound

for the purpose.

21.5.3 Lighting Fixtures in Film Vaults

(l)

Lighting fixtures in film vaults shall be of the explosion-proof

in Class I Group C hazardous globs.

type approved for the use

locations and shall have metal cages or guards protecting


EBCS-10 1995

the

403

j

~-L


(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 dusttight or enclosed types.

404

EBCS-10 1995


SECfION

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:

22.3

a) C22.1:1990


b) NFPA70/NEC:1986

National Fire Protection Association! American Electrical Code, 1987 Edition.

National

DEFINITIONS

(1) For the purpose of this Section, in addition to the terms defined in Section 1, the following definitions shall apply when referring to x-ray or computerized tomography equipment,

long-time rating

a rating that is applicable for an operating period of5.0min or more.

momentary rating

a rating that is applicable for an operating period of not more than 20.0s.


EBCS-10 1995

405


22.4

mGH-VOLTAGE

GUARDING

(1) High-voltage parts shall be mounted within metal enclosures that are bonded to eaith 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 CmCUIT

(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 bran~h 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

computerized tomography

rating of x-ray or·

equipment, whichever is greater, shall be provided in the supply

circuit in a location readily accessible from the radiation control.

406

EBCS-10 1995

ETHIOPIAN BUILDiNG CODE STANDARD

SECTION 22: DIAGNOSTIC IMAGING INSTALLATION

22.7

TRANSFORMERS AND CAPACITORS

(1) Capacitors fonning part of a diagnostic imaging equipment shall be provided with an automatic means for discharging and grounding 11leplates 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 2.5m of the floor.

22.8

CONTROL

(1) For stationary equipment, the low-voltage circuit of the step-up transfonner 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 (I) above, the design of the step-up transfonner

is such that 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 (I) 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

SO%

the mliximum 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) N on-current-carrying

parts of tube stands, tables and other 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 infonnation processing systems.

23.2

systems including

NORMATIVE REFERENCE

(1) The following reference corttains provisions which, through reference In this text, constitute provisions of the Ethiopian Building Code Standard on Electrical Installation of Buildings: a) C221: 1990

Canadian

Electrical

Code Part

1, Safety Standard

for Electrical

Installations, Sixteenth:'Edition.

23.3

GENERAL

. 23.3.1 Circuits in Communication Cables

(i) Radio and television circuits, remote control circuits, fire alarm circuits, or parts thereof shall be: a) pennitted to use conductors in a cable assembly of communication building entrance having other conductors used as communication circuits, b) deemed to be communication cir.cuits 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 conductors.


EBCS-10 1995

cable

409


23.3.2 Hazardous Locations (1) Where the wiring or electrical equipment within the scope of this Section' is installed in hazardous locations as defined in Sections II, 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 transformers 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 a'convenient and workmanlike manner. (2) Raceways for communication circuitsihall

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.

v

j

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 50.0mm 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~llsage 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 oLwithin 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 I 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 Boistways (1) Special permission shall be required to install communication conductors in hoistways.

ETHIOPIAN BUILDING COD

TANDARD

EBCS-10 1995

411


(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 eontain power and communication

conductors where SU9h cables are specifically approved for the

purpose.

23.4.9 ConductorS under Raised Floon (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 leasta SO.Omm separation is provided and maintained where the conductor,s 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 (1) 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 7S0.0mm, and any adhesive used shall be of release type; b) as an extension

Qf

conventional wiring to serve areas or zones, and each run of wiring

from the transition point ~all not exceed IS.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 (1) Type CFC system wiring shall not be used: a) outdoors or in wet locations; b) where subject to corrosive vapours or liquids; c) in hazardous locations; d) in dwelling units; e) in hospitals or institutional buildings except in office areas;

t) on walls except when entering the transition point; g) under permanent type partitions or walls.


EBCS-10 1995

413

------ ---


23.4.11.4 Floor protective coverings (1) Type CFC system wiring shall be covered with abrasion resistant tape, secured to the floor so as to completely cover all cables, corners, and bare conductor ends.

23.4.11.5 Coverings (1) 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 syste~ cables.

23.4.11.6 System height (1) Type CFC system wiring shall not be stacked on top of each other except as required to enter the transition point.

23.4.11. i" 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 (I)

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 of 900.0mm from electrical equipment requiring adjustment and maintenance shall be provided and maintained.

23.5.4 Earth Circuits (1) 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 (EELP A.).

23.6.2 Overhead Conductors on Roofs (1) Communication conductors passing over buildings shall be kept at least 2.5m 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.


EBCS-10 1995

415


23.6.3 Lightning Conductors (1)

Separation of at least 2.0m shall, where practicable, 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 of300.0mm from other underground system"s, 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 450.0mm shall be permitted, except that for service wire under parkways and lawns, the depth may be reduced to 450.0mm; d) be placed with a layer of sand 75.0mm deep, both above and below the cable, if in rocky or stony ground; e) not be less than 900.0mm deep 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 backfilling 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;

416

EBCS-10 1995

ET:..jIOPIAN BUILDING CODE STANDARD


f) not be placed in a common trench involving random separation with power supply cables or wires operating at over 750.0Y; and g) have a metal sheath when placed in a common trench involving random separation with power

supply cables or wiring operating

communication

at 750.0Y or less, in which case the

conductor or cable assembly shall not cross under the supply cable~,.

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 for the electric power system by not less [han 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

23.8.1 Bon~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.


EBCS-10 1995

417


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 10.0mm2 copper.

23.8.3 Earthing Electrode (1) Earthing conductor shall preferably be connected to a water-pipe earthing electrode as close to the point of entrance as possible. (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 cond~ctor of the power consumer's service. (3) In the absence of a waterpipe, the communication earthing conductor may be connected to an effectively earthed metal structure or to"an 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 normal length of driven earth rod used as the earthing electrode for a communication system is 1.5m; 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


SECTION 23:

ELECTRICAL COMMUNICATION SYSTEMS

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 (1) 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.


EBCS-10 1995

419

SECTION

24

CO:MMUNITY ANTENNA INSTALLATION FOR RADIO AND TELEVISION RECEPTION

24.1. SCOPE (1) 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


(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 1, Safety Standard for Electrical Installations, Sixteenth Edition.

b) lEC 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 of aerial performance specification, detailed specification sheet format.

420

EBCS~10 1995


-.-

-

SECTION 24: COMMUNITY ANTENNA INSTALLATION

c) IEC 728:1982

Cabled Distribution

System Primarily

Intended

for Sound and

Television Signals Operating between 30.0MHz and 1.0GHz.

24.3

TECHNICAL REQUIREMENTS

24.3.1 Mechanical (1) A community antenna shall comply with' all mechanical properties or requirements outlined in the IEC 597 and IEC 728.

24.3.2 Electrical (1) A community antenna shall: a) be desi.gned 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 (1) 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 liIllplifiers 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.

ETHIOPIAN BUilDING

CODE STANDARD

EBCS-10 1995

421


(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 EXDosed 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-use 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 by 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 shall also comply with the applicable Clauses of Sections 12, 13 and 14.

24.5.4 Supports (1) 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 (1) 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 (I) 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.


EBCS-10 1995

423

-,

ELECTfilCAL 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 run 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 of.an 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

ETHIOpiAN BUILDING CODE STANDARD

SECTION 24:

COMMUNITY

ANTENNA

INSTALLATION

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 I 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 Sectio~8 in addition to the insulation on the community antenna distribution circuit conductors, or the electric lighting power, and Class I 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 I circuit unless: a) the conductors of the community antenna distribution circuit are separated from the electric light, power, or Class I circuit conductors by an acceptable barrier, or b) the power or Class I 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.

ETHIOPIAN

BUILDING

CODE STANDARD

EBCS-10

1995

425


24.6.3 Penetration of a Fire Separation (1) 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 80

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 EELP A .

24.7.2 Overhead Conductors on Roofs (1) Community antenna distribution conductors passing over buildings shall be kept at least 205m 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 205m, measured vertically, of a roof without special permission.

24.7.3 Conductors on Buildings (1) 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 0

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 thwugh 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, Section25

24.8

of this Code.

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;


EBCS-10 1995

427


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 ~ver 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 systems:

raceway

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-ta!T';,r..l -.alth; 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 power 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 STANC,ARD


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 1 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 statio~ 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 24.9.2.2

material unless otherwise specified.

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


24.9.204 Mechanical protection (1) The earthing conductor shall be protected where exposed to mechanical injury.

24.9.2.5

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 Earthing conductors (1) The earthing conductor may be run either inside or outside the building.

24.9.3.3

Size of protective 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.1

Introduction

An efficient

antenna installation is one of the prerequisites for interference-free

radio and television transmission.

reception of

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.

Modern 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 fonn 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.1.3 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 followi~g data should be collected with the aid of the building plans 9r 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 detennined for the head station under the r<;>of.It must also be conflnned 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 detennined 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.3.1

General

The distribution system begins at the output of the head station and ends at the antenna socket outlets. Its purpose is to provide 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 neGessary. 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 (sockets fed in series, Figure AS) and spur sockets which are intended for main-feeder networks arranged in the spur-line pattern (sockets fed in parallel, Figure

A6).

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.

A7 shows the combined distribution method applied to a community antenna system with three television channels. Figure A8 provides a similar arrangement with six television channels. Figure

ETHIOPIAN BUilDING

CODE STANDARD

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 are 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

A.5.l

General

OF A RECEIVING-ANTENNA

SYSTEM

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.II and A.12. 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 LF/MFIHF 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



A.5.3 Minimum Antenna Separation Guidance values for the minimum separation post are given in Table A.I.

"a" in centimeters, between the antennas on the

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 I.Om. Table A.I Guidance values for the minimum separation "a" [em] between antennas on the spot

TV t

usw

TV III

TV IV

TVV

TVI

250

140

140

80

80

USW

140

110

80

80

80

TV III

140

80

80

80

80

TVN

80

80

80

60

50

TVV

80

80

80

50

50

ReceptIon

Band

A.5.4 Wind load and Bending Moment The bending moment in the tubular antenna post is calculated from:

(AI) where, L is length [m] and W is windload [N]. A post should be chosen where permissible bending moment (from the manufacturer's at least equal to the calculated bending moment

Mb

data) is

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 A13).

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 condensat.e 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 fTame.

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 assessmen.t criteria

interference For reflected

(8) relative to picture Not one visible half a12 G3 5Assessment times Forchannel common SO G2 GO criteria Just Not visible visible S2 R1 G1 S3 R3 3S1R2 RO interference (G) Clearly interference (R)

signal Assessment grades

nce

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 Maintenance 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 TPI and TP2. -

The checking and measurement results from each maintenance operation should be recorded in a suitable schedule Table A.4 for comparison with other tests.


EBCS-10 1995

437


Table A.3 Measurements on commis'sioning (entries in the measurement sch'edule)

)

IV x x Attenuati LF/MF ~hum, -6 dB TV xposition LF/MF~94 ote of ~S4 xxIVN~84 xreference xx commissioning Test-point and sound carrier mono ~40 Measurements of TV IIII hiss ~84 Observe maximum aerial' End TV 11~84 '!"N catalogue s80 data (see relative to~S7 Picture USW ~S2 stereo ~SO Signal-level permissible measurement' output Output of "lining-up" level according instructions) to signal (Values in dBI!V) quality Ouput of IVN FN5.W Sound quality signal levels in cable ~2 spur dB station or ~ Difference

cable of each main lead , receiver connecting

" n --TPO on Recommended distortio introduc noise and cracking, --TP3 FIMFI --TPI ~'TP2

additionalhead measurements ed by the TV channels between vision

x Insert appropriate entries 1)

For sound broadcast transmissions, the selectively measured transmitters in the LF, MF, HF and USW bands should be For television transmissions, the channel signal levels (the synchronizing pulses occur) in the receiving or distribution

2)

Assessment of picture quality,

438

EBCS-10 1995

carriers: at least the Lm,s. values of the local and district measured, r,m.s, level of the vision carrier at the point where the channels



Table A.4 Maintenance schedule Amplifier stati~~:m ...._mm ..m.. Consumer: _______________________

Address:

• __ ._.

__ • _ no

_.

Project : ~_n

_.

•• _ •• _.

Street No.:

- f------

t--

Ch .../. .. TP1

•

No.:

Date: TP2 TP2 R TP2 5TP1 G Name: aR Assessment of sound: Amplifier R Date: Name: [dB] Picture quality [dB] ~ignalleve nB,nt dB"V I '.hum, chrackling, noise, hiss) Geometry, Date: TP1 lSignal leve firmness .../. ... ./.. / ....... structure: Ch .. ./... .1... Aerial

_ ~ __ ••

• __ • u •••

__ •

• __ •

No.: wow. __ " •• _.".

_

Contract No.:

mechanical

j-----

Name:

Sealing of roofclamps lead-in Seating Equipotential of earthing bonding


EBCS-10 1995

439

LF/MF/HF/USWaerial

LF/MF/HF/USWaerial

/

DO

DO Aerial

sockel·

a) With one aerial socket

Figure A.I Structure of an individual aerial installation

b) With two aerial sockets and an amplifier


CP WC nelWQrk

Main dislribution fed from below

Connection point Wlde.ban~ c.ble nelw07<

'\'HF wide·bRnd amplilier 11 :>Iece 01 previous r.eJd slallon in loll ,":MRln distribution , , ,\system, fed Irom above

system',

'CP 10 WC nolWolk In basement' '

Apartment building

a)

New buildings connected to wideband cable system

b) Existing community aerial installation

Aar\ill structure

Figure A.2 Private wide-band systems

Figure A.3 Structure of a community aerial installation with 24 subscribers


EBCS-10 1995

441


MWl -4

I

I

caol,

I ). .••• ay. t Ol$UlbYllOt\

l14.'#j'V d"lfibullOn

I 2'WlY : dlSUlDullOfl

"r-~-ll" ~ ~ l

:I

::

f'J"rII

II

•

' Sino"

blanf\lng

OtSlr1OUl!Of'it 00 ••0" caDIt. I brHM:/\JnQ

--At:... '[1' r--u-ffr--.---""'l'---DO' •••"n"b"_~: .::::

:: : I::I II:I: II ~

O'SU'10uhOn l;iol ••

a) Dinribution bOA~ ror IWO, three ~nd fout m;l,in ~blC1

I

II

I

:I

DlllllbuiiOt'l "1>1'

OllUlbuuOl

tlOll

b) Br;\.nchi~, bOlU fur one and fWD main cilbici

Figure A.4 Types and applications

of junction boxes

.

~~DULIOn ,

Oi.lnbYlio-l

eaol.

DoYOI, orlnct\lno l.rn;na1lng

.(all~ iOCAtl wiln ttlITMlling;ft$ISIOf

bOl. .•••• 11';

i'·.•.• I'JS C'U:

(7$ OJ

Figure A.S Through-wired

442

' ••

EBCS-10 1995

method

Fig. A.6 Spur-line

method



II ~I ~' Ch

I Ch I I 6· Ch 21 USW

t

IIIII 'ft

tlFI

I 12 eh 3~ Ch 8 Ch th8 'ft

II

LF/MFI

C~2

Figure A.7 Community aerial system for LF MF, HF and USW reception and three television transmission

Figure A.8

Community aerial system for LF, MF, HF and USW reception and six television transmissions

Privale wide;band

system

Figure A.9 Wide-band cable network with private wide-band system


EBCS-10 1995

443


\

\

I

I I I cuismm'l

III I I

I

1:1,L2: L1

-

N - neultill

Phis. conductors conductor

I I

Figure A.tO Protection of an aerial installation by inclusion in the equipotential bonding of all the metallic conducting systems of a building

LF/MF/HF

aenal

f IV,

USWaerial

1,I

I

a

L

J

I

Figure A.l1

444

UHF aerial

a

VHF~al

Data relevant to the length of, an aerial post

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

Ring section complelely lemovl1d oV,era lenglh 015 mm allhe Ipwesl point ollhe waler Irap or,shealh

Figure A.14 Formation of a "water trap"


EBCS-1d ·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 tenn "pool", as referred to in this Section, is deemed to include permanently installed and storable pools, hydromassage

25.2

bathtub, spas and hot tubs, wadding pools, baptismal pools,'and

decorative pools.

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

a pool constructed in such a manner that it may be readily disassembled for storage and reassembled to its original integrity.

446

EBCS-10 1995


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 1.5m 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


25.4.2 25.4.2.1

Overhead Wiring General

(1) There shall not be ~y 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 I 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 ~xtending 3.0m

horizontally from the pool edge, provided there is a clearance measured radially of at least 4.5m. 25.4.2.3

Conductors oper4ting at no more than 50.0kV

(1) Conductors other than those covered by 25.4.2.2 and operating at not more than 50.0~Y phase-to-phase shall be permitted to be located above a pool, diving structure, observation stand, tower or plate, or above the area extending 3.0m horizontally from the pool edge provided there is a clearance measured radially of at least 7.5m.

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 , 0- 750.0V

25.4.4

Bonding to Earth

25.4.4.1

General

0.75 2.00 1.50 4.00 3.00 0.75in 1.5 0.75 raceways Conductor underground Conductor Minimum buried directly in separation

[m]

(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

Reinforcing steel

(1) Pool reinforcing steel shall be bonded with a minimum of four connections equally spaced around the perimeter.


EBC$-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 be 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 I)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 (I)

Deck boxes

Junction "installed on the supply side of conduits extending to fonning

shells, referred

hereinafter as "deck boxes", shall be specifically approved for the purpose and shall: a) be provided with a means for independently tenninating at least three bonding conductors inside the box and one 16.0mm2 bonding conductor outside the box; b) not contain the conductors of any circuits other than those used exclusively to s\lPply the underwater equipment; and c) be provided with electrical continuity between every connected metal conduit and the bonding tenninals 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 nonnal 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 be an 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) Transfonners

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 transfonner

25.4.6.2

not accessible to persons using the pool area.

Bonding

(I) A metal shield, if provided between the primary and secondary windings of a transfonner, shall be bonded to earth.


EBCS-10 1995

451

ELECTRICAL INSTALLATION OF BUllDtNGS

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 3.0m 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 pools. 25.4.7.2

Protection

(1) Sockcl Dutlets located between 1.5m and 3.0m of the inside wall of a pool shall be prote~ted by an earth-fault circuit breaker. Note:

In maintaining the dimensions 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

Accessib~lity

(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 permanent barrier shall be electrically protected by an earth-fault circuit breaker.


EBCS-10 1995

453

ELECTRICAL

25.4.8.6

INSTALLATION

OF BUILDINGS

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 typet.

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

(1) 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

Warning sign

(1) A warning sign shall be located beside the switches controlling 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

ETHIOPIAN

BUILDING

CODE STANDARD


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 25.4.5 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 Circuft Segregation (1) Conductors independent

on the load side of each earth-fault circuit breakers shall be kept entirely

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 ofthe pool walls shall be specifically approved for the purpose. 25.6.2.2

Supply

(1) Swimming pool pumps shall be supplied from a pern'lanently 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.Om horizontally from a wall of the bathtub unless they form an integral part of an approved factory-built hydromassage bathtub.

456

EBCS-10 1995



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

(1) 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


(1) A copper bonding conductor whose size is not less than that of the circuit conductors supplying the equipment shall be connected between the 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

(1) 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

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 of a 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 pump marked as "insulated wet-end pump".

25.8.3.2

Insulation and bonding

(1) Leakage current collecto~hall

is a

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


(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 III 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


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

(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.

Note:

No conductors

would be permitted under any circumstances

Line I insulated communication

in the area under line I. In the area above

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.I

A (INFORMATIVE)

AUDIO ISOLATION TRANSFORMERS

Audio isolation trans formes should:

a) have either the primary and secondary windings wound on separate bobbins 'On the core legs or a grounded and

metal shield between the primary and secondary windings;

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

preamplifier,

amplifier or similar equipment.

A.2

conductors installed between them and any mixer,

AN EARTH FAULT CIRCUIT INTERRUPTER

An earth-fault

circuit interrupter

is a device whose function

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 device of that circuit.

is to interrupt, the overcurrent

WHnm a protective

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 f~,ult current is 4.0mA or less in a time: a) not greater than that given by:

T

46.0

20

I

EBCS-10 1995

(A.I)



where

T is the time in seconds,

I is the earth

fault current in La.ms milliamperes for fault current~ between 4.0mA and 260.0mA.

Note: when the ambient air temperature is less than -SoCor more than 40°C, 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 load. 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.

ETHIOPIAN BUilDING

CODE STANDARD

EBCS-10 1995

46·1

r

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)

mc

529:1989

b) DIN 407117:1983

26.3

Degree of protection provided by enclosures (IF Code). Graphical Symbols Installation.

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 of protection

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 mc 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 mc 529:1989.

462

EBCS-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

// / -----

-"• \J'-...

symbols for electrical installations

Overhead line Radio Signal line Telephone Protective Surface line Conductor line (PEl installation Underground line for flush DESCRIPTION Flexible conductor Junction of line conductors In/Under surfaceline Wiring going down Wiring going upward Wiring passing through vertically Identification Supply Installation Method general Identification ofof Intended lines Application Conductor, line Systems SYMBOL

--

Note:

Darkened symbols indicate flush [recessed] installations.


. EBC$-1 0 1995

463

ELECTRICAL

INSTALLATION

OF BUILDINGS

Table 26.1 Graphical symbols for electrical fnstallations (conte'd)

DESCRIPTION

SYMBOL

Supply Lines (conte'd)

--0--

Junction of conductors

for surface installations

Earthing Surface mounted (central) main distribution board Flush mounted (central) main distribution Surface mounted sub-distribution Flush mounted sub-distribution

board

board board

Switchgear Fuse, general Three-pole fuse, general Low voltage HRC fuse Fuse disconnector Switch Automatic

breaker for line protection

Breaker with thermal over-current

trip, e.g

Motor circuit break-et Star-delta Motor Starter

o irect-on-I

ine starter

Switches used for installation purposes On-off switch, single-pole On-off switch, double-pole On-off switch, triple-pole Two-circuit Two-way

switch, single interruption. switch, single-pole

Push-button

Note:

464


EBCS-10

1995

ETHIOPIAN

BUILDING

CODE STANDARD

SECTION 26:

GRAPHICAL_SYMBOLS

Table 26.1 Graphical symbols for electrical installations (conte'd)

mp -

®

/,.0\

)( I

Socket Outlets purposes (conte'd)

/

DESCRIPTION Time Dimmer switch switch TelephoneSYMBOL outlet ,socket Empty box Twin socket outlet Florescent luminaire single lamp + PE general symbol Luminaire Emergency Wall mounted with luminaire switch luminaire -Float switch Flood light (Projector) single-phase Time relay socket outlet Socket Antenna Current outlet pulse socket with switch outlet switch Light-sensitive switch Three-phase Single-phas'e socket socket outlet outlet+ PE Luminaires '~ ~

rh

7

,

'~-Note: Darkened symbols indicate flush [recessed] installations


EBCS-10 1995

465


Table 26.1 Graphical symbols for electrical installations (conte' d)

-0.

I [Z] -Ir-0+® f®l ~~ ~ -CID0 Luminaires(conte'd) IKwhm [£J ®®®S

I

I xI I I florescent luminaire xSYMBOL I of DESCRIPTION Row Water heater Florescent luminaire double lamp Battery (Cell) Inverter Current transformer Rectifier Voltage transformer Indicating instruments Microwave cooker Exterior luminaire (post top) symbol Metre (ki lowatthour-metre) Washing machine Kitchen Hotplate appliance Electrical Electric Convertor Baking oven range, appliance, General general Symbol General symbol

Indicating Electrical Instruments Appliances (Power) Transformers Power Supplyand Units

Note:

466


EBCS-10 1995


SECTION 26:

Table 26.1 Graphical

GRAPHICAL

symbols for electrical installations

SYMBOvO

(conte'd)

SYMBOL I DESCRIPTION Non-automatic fire alarm deviceindicates (manual call fire Call indicator panel (Number Horn Electric Clock Bell alarm Motor Freezer fan Generator Master Siren Clock Smoke detector Dish Intercom washer Telephone Automatic Telephone exchange, exchange general panel symbol Fire Deep freezer control & indicating Air conditioning Clothes dryer call point) stations, for example 9 stations) CJ:=:=7 Communication appliances 1** I ~ [Q] [*** E!J ~ ~ Signalling Devices Lf-o-Jlj Electrical Appliances(conte'd) I

U g

=:j) 0 @ I~l ® II=:JI ®

J

1

Note:

Darkened

ETHIOPIAN

symbols indicate

BUILDING

flush [recessed]

installations.

CODE STANDARD

EBCS-10

1995

467


Table 26.1 Graphical symbols for electrical installations (conte'd)

lr

SYMBOL

detector (rate of rise) Radio, Television and accessories oJ I=:::: =:::) 1ZSJ II

EJ em

Note:

468

-

..

----

DESCRIPTION , Antenna TV set Flame Loud Radio speaker set Heat detector (fixed temperature) Amplifier Optical detector ,.detector


EBCS-10 1995


SECTION 26:

GRAPHICAL

SYMBOLS

Table 26.2 Graphical symbols for the degree of protection of electrical equipment (symbols on light fittings)

••

I

SYMBOL

Type of IIII1.0mm rain Covered covered dust foreign 1.0mm 2.5mm protection ~water foreign substancesagainst splash IPproof 67substances waterproof substance jet ~water inclined dripping water nowaterproof protection IP 22 no 50 IP 60 54 IP 43 44 65 23 IP 55 53 2nd Digit - Protection 11s1 Digit - Protection against

-----,

ETHIOPIAN BUILDING

CODE STANDARD

EBCS-10

1995

469

ANNEX

A

(INFORMATIVE)

SYMBOLS ON LIGHT FITTINGS COMPLYING WITH IEC 598 •.

Test marks

Lighting fittings for discharge lamps for direct mounting on fixtures and furnitures, which conform in their • SYMBOL Lighting fittings suitable formounti mounting in fire-hazardous locations andElektrotechiker" premises (VDE 0100) DESCRIPTION It certifies the of mounting IPprocedure 50 (~Association (dust Lighti ng fitti ngssuitable for on association materials with unknown inflammabi Iity.The The VDE-test mark is the symbol ofng the "Verein Deutscher of Impact proof lighting fittings are suitable for gymnastic and sports prem ises. The tests are made accordi ng ?t at 200°C, Radio interference suppressionaccording to VDE 0875. All lighting fittings conform to the interference to DIifNthey 18032 and or VDE 0711. varnished, coated veneered. German Electrical Engineers.) The is deformation based specified C-specifications. lighting fittings for discharge lamps with on this internationally sign are suitable for direct mounting on being normal or easily suppression degree G. By using additional interference suppression device degree will be reached. is specified. behaviour for inflammation to hardly or normally inflammable materials, although ifNrules. these materials and remain stable and are notapproval subject to upto this temperature.

W

W VJ W @

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.

lamps for connection to low voltage with ProtectiveDESCRIPTION insulation, wire required

SYMBOL protective a insulation is, wire (Max. protective Class Class III

quired. protective wireprotective isallowed. not fitting has For Iighting fittings with incandescent

--

ETHIOPIAN BUILDING COi)&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-1

ELECTRICAL

INSTALLATION

OF BUILDINGS

a) b) c) d)

connection of conductors; identification of conductors; routing of cables in safe zones or mechanical protection; selection of conductors for current carrying 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, ill) protection by obstacles, iv) protection by placing out of reach;

,

i)

methods of protection against indirect contact; i.e, i) presence of protective conduqtors, 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)

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); labelling of circuits, fuses, switches and terminals; selection of equipment and protective measures appropriate to external influences; adequacy of access to switchgear and equipment; presence of danger notices and other warning notices; presence of diagrams, instructions and similar information; erection methods.

k) 1) m) n)

0) p) q) r) s)

A-2

EBCS-10 1995


APPENDIX 1: INSPECTION AND T1STING

1.3

Testing

1.3.1

Tests to be 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)

c)

A test shall be made to verify the continuity of each conductor, including the protective conductor, of every ring final circuit.

Insulation resistance i)

The insulation resistance between live conductors shall be measured before the installation is connected to the supply. ii) 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. iii) 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. iv) 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. v) The testing equipment shall be capable of supplying the test voltage indicated in Table A.1 when loaded with 1.0mA. vi) 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

ELECTRICAL INSTALLATiON OF BUILDINGS

resistance between the exposed conductive parts and live parts of the disconnected equipment shall be measured separately and shall be not less than O.5mega Ohm. Table 1: Minimum values of insulation- resistance

[V]

Minimum 0.5 insulation resistance 1.0 5.0 1000 Circuit nominal voltage [V]0.25 ~O Test voltage (mega Ohms) 500 d.c. circuit is supplied from a safety Above 500.0V up to 500.0V 1000.OV Up to and including with the

Note:

i)

In the event of any test indicating failure to comply with the requirments of clause (lc) above, that test and those preceding it (the results of which may have been influenced by the indicated fault) 3hall 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 (IEE); 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.

l

e) Protection by separation of circuits (i)

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.

(ii)

t) 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 lP2X or lP4X as appropriate.

g) Insulation of non-conducting floors and walls Where protection against indirect contact is to be provided by a nonconducting 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 12m from any ~xtraneous conductive part in the location. The other two measurements shall be made at greater distances.

(i)

(ii)

Any insulation or insulating arrangement 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~-l 0 1995

A-5


- centre-contact bayanet and Edisan screw lamphalders in circuits having an earthed neutral conductar have the auter ar. screwed contacts connected to. the neutral conductor; and - wiring has been correctly connected to. sacket-autlets and similar accessanes. (i)

Earth fault laap impedance i) Where protective measures that require a knawledge af the earth-fault laap, impedances are, the relevent impedances shall be measured. Earth electrode resistance

G)

i)

(k)

Operatian af residual-current aperated devices (i)

2

Where pratective measures are used, which require a knawledge af the earth electrode resistance, this shall be measured.

Where pratectian against indirect contact is to. be provided by a resi~ual current device, its effectiveness shall be verified by a test simulating an appropriate fault conditian and independent af any test facility incorparated in the device.

ALTERATIONS AND ADDITIONS TO AN INSTALLATION

(1) It shall be verified that every alteratian or additian complies with the requirements af this Co.de and that it daes nat impair the safety af an existing installatian. 3

PERIODIC INSPECTION AND TESTING

(1) Inspectian comprising careful scrutiny af an installatian shall be carned aut withaut dismantling or with partial dismantling, as required, supplemented by testing to.provide far: a) the safety af persans and livestack against the effects af electric shack and burns even when the circuit is defective, b) pratectian against damage to. praperty by fire and heat arising from an installatian defect,

A-6

EBCS-10 1995


'"

APPENDIX 1: INSPECTION AND rESTING

c) the identification that the installation is not damaged or deteriorated so as to impair safety; d) the identification of installation defects or non-compliance with the requirements of this Code which may give rise to danger. (2) The frequency of periodic inspection and testing of an installation shall be determined by the type of installation, its use and operation, the frequency of maintenance and the external influences to which it is subjected. 4

CERTIFICATION AND REPORTING

4.1

General

(1) Following the initial verification required by Clause 1 or Clause 2 of this Appendix, a Completion & Inspection Certificate in the form set out in Appendix 2 of this Code shall be given to the person ordering the work. (2) Following the periodic inspection and testing described in Clause 3 of this Appendix, report on the findings and the extents of the periodic inspection and. testing of an installation, or any part thereof, shall be recorded on a report and given by the person carrying out the inspection, or by a person authorized to act on his behalf, to the person ordering the work. (3) Dangerous conditions arising from non-compliance with this Code, together with any limitations of the inspection and testing in accordance with Clause 3(1) of this Appendix, shall be recorded.

4.2

Initial Verification

(1) The Inspection shall comply with the requirement of Clause 1 of this Appendix and any defects or omissions revealed by the inspection shall be made good before a Completion & Inspection· Certificate is issued. (2) The Completion & Inspection Certificate shall be signed by a competent person or persons stating that the installation has been designed, constructed and inspected and tested in accordance with the provisions of this Code.


EBCS-10 1995

A-7


4.3

Alterations and Additions

(1) The requirements of Clause 4.2 fdr 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

ETHIOP!At'-J 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.

ETHIOPIAN

BUILDING

CODE STANDARD

EBCS-10 1995

A-9

FORMS OF COMPLETION & INSPECTION 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 extent 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 the 'Construction of the electrical installation, particulars of which are described on Page.... of this Form CERTIFY that the said wt>rkfor 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: (3) Date:

(2) Signature: 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 l/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 ~rtificate. For the

INSPECfION

AND TEST


of the installation: Position:

Reg. No.

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:

!

APPENDIX 2: FORMS OF COMPLETION AND INSPECTION CERTIFICATE

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 design. construction and inspection and testing 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-ll

PARTICULARS OF THE INSTALLATION (Delete or complete items as appropriate)

Type of Installation: Type of Earthing:

New/Alteration/Addition/ to existing installation

o TN-C

Earth Electrode:

0 TN-S

0 TN-CS

0 IT

0 IT

Resistance

................. ohms

Method of Measurement Type and Location Characteristics of the supply at the origin of the installation: ............. Volts

Nominal voltage Frequency Number of Phases

............. Hz .

Prospective short-circuit current

................kA

Earth fault loop impedance (z.)

.................ohms

Overcurrent protective device:

Type

.

Main switch or circuit-breaker

Rating ..... A .

(if an r.c.d., rated residual operating current

oo for No Method of earthing: 0 ready Cable operation sheath.o satisfactory of unsatisfactory on isforeffective. earth-leakage protection. ich oearthing Additional overhead line conductor Buried strip/rod/plate o Earth-leakage circuit-breaker, current Protective multiple (p.M.E.) voltage operated Earth-leakage protection is afforded by a 0 current.-operated. impedance of each earth-continuity conductor is satisfactory:

Rating .... A..

o

IdB ••••••••••••••••• mA.)

DYes voltage-operated

No of poles

.

APPENDIX 2: FORMS OF COMPLETION

AND INSPECTION CERTIFICATE

DYes DYes DYes oo No oNo No the installation is correct Polarity throughout stated below: Each item of apparatus tested separately is in good serviceable condition, except as stated below. parately is not less than 0.5 megao ] llation is not less than 1 megohm All flexible switches, fuses,ofplugs and socket-outlets are except in goodas serviceable cop-dition, except as There is nocords, sign of overloading conductors or accessories stated below.

m.

o

Apparatus tested

includes

o

does not include

portable appliances.

Comments (if any) and departures from the WiriJilgRegulations:

Date:

Signed

For and on behalf of: Address:

.

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

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

ETHIOPIAN

BUILDING

CODE STANDARD

EBCS-10 1995

A-13

INDEX

A Accessibility 453 Air blower installation 459 Air conditioning 380 Alarm signals 346 Ambient temperature 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 openiJ).g 358

B

Control required 266 Control switches 320 Controls 457 Controls location 456 Corrosion 192 Coverings

414

D

Deck box installation Deck boxes 451

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 luminaire 453

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

E Earth electrode seal for use within a tanked structure 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

c Capacity of protective gear 147 Car lighting and accessories 380 Ceiling 353 Ceiling outlet box wiring 325 Charging facility 360 Circuit connection 360

192

E,arthing Conductors conductor /,0 430 be run in a straight lille 430 Earthing Earthing electrode 430 Earthing of shields 414 Electric lifts 383

Circuit segregation 455 Clothes closets 320 Colour coding 323 Colour rendering 7 Common earth 430 Communication conductors and cables not exceeding 750V 448

j

Enclosed or guarded live parts 144 Equipment 385 Equipment and power supply 346 Excess load 400 Explosive on flarnnlable atmosphere 347 External metal 189

F

Component 459 Concrete - enclosed electrode 169 Conduit type 455 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 attaclunent 331 Conductors cross section 357 Conductors operating at no more than 50 k.v. 448 Conductors to individual motors 257 Conduit seal 148 Conduitto 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 Continuous duty 384 Control location 267 Control 327

171

Fault signal discrimination 347 Feeder conductors 259 Feeder 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 voltag~ 358 Hoistway door interlocking wiring 378 Hydraulic lifts 383

I Illuminance 37 Illumination level 387 In hoistway, machine rooms and escalator wellways 379 Independent metal water pipes 168 Installation and bonding 458 Installation 357,375,400,454,458 Installation and type 148 lnstanteneous trip circuit interrupters 262 Insulation 429 Insulation rating 378 Insulation resistance 356 Internal metal 189 Interruption

Mechanical and electrical requirements 188 Mechanical protection 430 Metal car frame supported by cables 385 Metal casing of a pump 169 Metal parts 453 Meters instruments and relays 284 Minimum height ofluminaries 322 Monitoring 350 Motor supply conductor insulation, temperature 257 Motors and generators 285,286,287 289, 2~1, 293 Motors and generators 285 Motors and generators 286 Motors and generators 287 Motors and generators 289 Motors and generators 293 Multiple services 142

N

Near or over combustible material

320

Non - continuous duty 384 Number and location of overload devices 263 NUmber ·of circuit element 347

o

361

J

On cars 379

J~ints 189 Junction box bonding conductor 450

L Labelling 361 Lamp holders 326, 332 Lantern lights 351,353 Laying 170 Lengt11of cable from transformers 376 Lighting 386 Lighting fixtures 292 Lighting fixtures 285,286, 288,290 Lighting switch 387 Linllts of spacing 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 exposed to flying objects 322 Luminaire in damp or wet location 320 Luminaire support 453 Luminaries 458

375

Over current protection 146,327,362375 Over load and over heating protection 362 Overcurrent protection marked on equipment 260 Overheating protection required 265 Overheating protection required 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 of future equipment Protection 319 Public water pipe

189

168

R

M Manual call in automatic alarm

Open core - and soil type transformer Origin of call indication 348 Other wiring 378 Other classes 454 Other factors 354 Outlet boxes to be covered 322 Outlet distance 400

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 selection of overload devices Recessed luminaire 322 Recessed luminaire wiring Reinforcing steel 449 Remote location 361

263

324

-~

INDEX

Use of insulators

Response time 38 Restricted alanns 355 Rod electrode 170

s

v

Sandy or gravely soil 191 Secondary conductors 259 Secondary voltage 374 Sectioned rooms 351

Ventilation

w Warning sign 454 Wet niche or submersible luminaire

Sock~ outlet 387,458 Soilless than 0.3m 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 Stationary motors 257 Storage - battery charging equipment 292 Stricken 349

267

Submersion qepth 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 326

284, 287,289,290, 375

293

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 Undervoltage protection required for motors 265

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 Wiring of show-window luminaries 325 Working space 145

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 351

Transformers and capacitors Transformers used outdoors

374

Visual alarm signal 356 Voltage 31'),453 Voltage drop 399,400

Segregation 358 .Segregation 397 Sequence of control 147 Service equipment 328 Shallow top soil 191 Short circuit protection 362 Show windows 320

Thermal protection lbickness 374 Times switch 456 Transformer 326

331

Use of messenger cables 333 Use permitted 413 Use prohibited 413

266

EBCS-10 Ethiopian Building Code Standard Electrical Installation of Buildings

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