Sharjah Regulations

SEWA Regulations for Electrical Connection

Rules and Regulations of Electrical Connection

Sharjah Electricity & Water Authority Directorate of Transmission and Distribution Page 1


CONTENTS SL NO 1 2 3 4 5 6 7 8 9

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TOPIC General Requirements Definitions Requirement for Safety Substation, Services Arrangement & Distribution Boards Earthing Arrangements And Protective Conductor Conductor Installation Details Final SubSub-circuit Power Factor Correction Equipment / Capacitor Bank Electrical Motor , Circuits & Controllers

PAGE 3 11 26 31 53 68 92 100 114

10

AppedixAppedix-1 Spacing Of Supports For Trunking , Conduits And Cables

120

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Appedix Appedixix-2 Earth Leakage Protection

124

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AppedixAppedix-3 Current Rating For Single And MultiMulti-core Cables

127


Section -1

GENERAL REQUIREMENTS 1-1 Scope 1-1-1 These regulation are applicable to electrical installations in buildings in general including domestic premises , shop , office , small , medium and large sized residential , commercial and industrial

1-1-2 All the projects shall be subject of detailed study by SEWA (Sharjah Electricity and Water Authority) of the submitted and approval obtained before commencement of construction.

1-1-3 Compliance with these regulations is compulsory electric power supply will not be made available if these regulations are not met with their entirely any deviation to this regulation to be noticed to the SEWA by contractor or consultant.

1-1-4 The regulation are not intended to take the place of detailed specification or to instruct untrained persons or to provide for every circumstances where difficult or special situations arise which are not covered or allowed for in these regulations the services of SEWA may be sought to obtain the best solution.

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EXCLUSIONS FROM SCOPE

1-1-5 These regulations do not apply to: 1. Those aspects of installation in potentially explosive atmosphere relating to methods of dealing with the explosion hazard which are specified in BS5545 and CP1003 in premises where the fire risks are of a usual character so as to require special measures. 2. Those parts of telecommunications (eg: radio telephone bell call and sound distribution and data transmission) fire alarm intruder alarm and emergency lighting circuits and equipment that are fed from a safely course. Requirements for segregation of other circuits from such circuits are however included. 3. Electric traction equipment.

4. Electrical equipments of motor vehicles except those to which the requirements of these regulation concerning caravans are applicable. 5. Electrical equipment on or off shore installation, board ships, aircrafts. 6. Installations in mine and quarries. 7. Radio interference suppression equipment, except so far as it affects the safety on an electrical installation.

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8. Lighting protection of buildings (for guidance see BS CP 6651)

1-2

Electricity Supply and fault levels : 1.

The nominal electric supply voltage from SEWA is 415/230 Volts + 10% at 5o Hz 3 phase 4 wire with separate neutral and protective conductors as per (IEC-38) generally metallic covering of the cable supplying the installations) the neutral is solidly earthed at SEWA substation and shall not normally be earthed elsewhere in the electrical installations.

2. All equipments apparatus, material and accessories used in the electric installation shall be designed and rated for the operation on this electric supply. 3. Appropriate protective device against over voltages, transient harmonic fluctuations, loss off one or more phases and any un foreseen interruption shall be provided in all consumer installations as deemed essential in addition to over load, short circuit and earth leakage protective devises (usually in ACBs). 4. The design fault level depends on substation KVA rating the following table indicates the accepted KA rating levels for the various KVA ratings of Substations

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TR KVA

MDB I/C

MDB O/G

SMDB I/C

SMDB O/G

1500

60KA

55KA

35KA

25KA

1000

55KA

50KA

35KA

25KA

500 250

45KA 40KA

45KA 35KA

35KA 35KA

25KA 25KA


1-3

Climate conditions :

Sharjah experiences a tropical climate and generally the ground area is at sea level. The maximum ambient shade temperature recorded has been 52°C and the minimum 2°C. The maximum ground temperature in 35°C at a depth of 1 meter and the maximum sea water temperature is 40°C with maximum tidal variation of approximately 2.4 meter. The wind speed is 45 m/s at 10 meters height, the prevailing winds are northerly and gales with guts and it have been recorded a combined by a high level of dust in air. The atmosphere is salt laden and very corrosive with a soil thermal resistivity of 2c/m/w. All equipments, apparatus, accessories used in electrical installation shall be suitable for the operation with satisfactory performance in the above mentioned climatic conditions.

1-4

Approved contractors and Workmanship:

All electrical installation works, new and or additions shall only by carried out by licensed contractors as authorized and classified by SEWA. Each contractor who undertakes electrical installations is required to have sufficient no of engineers, engineer assistants, foremen, electrician, electrician helpers as per SEWA contractors’ classification rules, all above persons have to attend the competency exam to perform electrical works and the contractors have to categorize in accordance to the size of work they can do according to stuff they have. (for further details of contractors classification refer to SEWA office. The competency licensees and final completion certificates will be issued only to categorize contractors after fulfill SEWA requirements. Electrical contractor's responsibility is to carry out all electrical works in a neat orderly workmen manner and to bay attention to the mechanical execution of the work in connection with any electrical works.

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1-5

Standard for Material and Equipments:

All materials used in electrical installation shall be of good quality and shall comply as a minimum with the latest relevant recommendations issued by SEWA of the international electro-technical commission,(IEC) And if this is not available to the latest relevant British standard Specification (BSS). Material of other national standard may also – be employed provided they are comparable with IES/BSS. Materials must also be approved by SEWA before use. In case of doubt of acceptability of materials already used; the contractor may be required to approve the material, material supplier, and manufacturer from SEWA before using the subject material. Manufacturer's name, trade mark or other descriptive marking to identify manufacturer is to be present for all electrical equipments. For accessories the marking shall be of sufficient durability to with stand the environment involved.

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1-6

Submission of Drawings:

Before the commencement of any electrical installations, large or small, new or, additional, the following details and drawings of the proposed installation shall be submitted to SEWA for the review and approval thereof. 1-6-1 Owner passport copy 1-6-2 Affection plan, and site setting out plan 1-6-3 Land ownership 1-6-4 Drawing checklist form stamped by consultant. 1-6-5 Complete set of electrical drawing showing connected load. 1-6-6 single line diagram, load distribution schedules. 1-6-7 Wiring lay outs of the installation. 1-6-8 General arrangement and dimensional layout of electrical and substation rooms, meter arrangement details. 1-6-9 Complete set of A/c drawing, thermal load calculation, wall section details windows detail. 1-6-10 complete set of detailed switchgear drawing and technical submittal to be submitted in latest stage of project execution. Consultant is responsible to obtain the necessary approval for the above mentioned subject from SEWA.

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1-7

Harmonics Transient, Rapid Voltage Changes:

An assessment shall be made of any characteristics of equipment likely to have harmful effects on other electrical equipments or other services, or likely to impair the supply. These Characteristics include, for example; 1) Transient over voltages 2) Rapidly fluctuating loads. 3) Starting currents. 4) Harmonic currents (such as with florescent lighting /loads and thyristor drives) 5) Mutual inductance. 6) DC feedback. 7) High frequency oscillations. 8) Earth leakage currents 9) Any need for additional connection to the earth (e.g.; for equipment needing a connection with earth independent of the main means of earthing of the installation , for the avoidance of interference with its operations.)

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Note: for an external source of energy it is essential that the authority of electricity and water be consulted regarding any equipment of the installation having a characteristics likely to have a significant influence of the supply, e.g. Having heavy starting currents.

1-8

Maintenance periodic inspection and checking:

An assessment shall be made of the frequency and quality of maintenance the installation can reasonably be expected to receive during intended life. This assessment shall, whenever practicable, include consultation with the persons or body who will be responsible for the operation and maintenance expected, the requirements of these regulation shall be applied so that; 1) Any periodic inspection, teasing, maintenance and repairs likely to be necessary during the intended life can be readily and safely carried out, and 2) The protective measures for safety remain effective during the intended life and 3) The reliability of equipment is appropriate to the intended life.

1-9 Inspection and testing of installations: Contractor shall be required to submit their inspection certificated in the prescribed form given in the appendix on completion of the electrical installations. All installation and equipments installed therein shall be subject to SEWA inspection testing and final approval before connecting to the electric supply.

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Section -2

DEFENITIONS Accessory: a device, other than current-using equipment, associated with an Electrical Installation. Appliance: an item of current-using equipment other than a luminance or an independent motor. Arm’s Reach: a zone of accessibility to touch, extending from any point on a surface where a person may stand or move about, to the limits which such person may reach 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 which does not necessarily include insulation used exclusively for functional propose.

Bonded: Connected together electrically not normally for the purpose of carrying current but so as to ensure a common potential.

Bonding conductor: A protective conductor providing equipotential bonding. Building void, accessible: A space within the structure or the components of a building accessible only certain joints. Building void, non-accessible: A space within the structure or the components of a building which has no ready means of access.

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Bunched: Cables are said to be bunched when two or more are contained within a single conduit, ducting, or trunking or, if not enclosed, are not separated from each other by a specific distance.

Cable bracket: A horizontal cable support system, consisting of elements fixed at one end only, spaced at interval along the length of the cable end 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 the access to the conductor and or cables throughout their length during and after installation. A cable channel may or may not from 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 and which mechanically retains the cable or conduit.

Cable coupler: means of enabling the connection or disconnection, as will of two flexible cables. It consists of a connector and plug.

Cable Ducting :A manufactured enclosure for material or insulated material, other than conduit or cable trunking, intended for the protection of cable which are drawn in after erection of ducting.

Cable tray: A cable support consists of continues base with raised edges and no covering it is considered to be non- perforated, where less than 30% of the material is removed from the base

Cable tray: A cable support consists of series of supporting elements rigidly fixed to main supporting elements occupy less than 10% of the plan area.

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Cable trunking: A manufactured enclosure for the protection of cable, normally of rectangular cross- section, of which one side is removable or hinged.

Cable tunnel: An enclosure containing supporting structures for conductors and/ or cables and joints and whose dimensions allow persons to pass freely throughout the entire cable length.

Caravan: A trailer leisure accommodation vehicle , used for touring, designed to meet the requirements for the construction and use of road vehicle.

Caravan Park: An area of land that contains two or more caravan pitches. Caravan Pitch: A plot of ground upon which a single leisure accommodation vehicle or leisure home may stand. Caravan Pitch Electrical supply Equipment: Equipment that provides means of connecting and disconnecting supply cables from a leisure accommodation vehicle to a fixed external power supply.

Cartridge fuse link: A devise comprising a fuse element or several fuse elements connected in parallel enclosed in a cartridge usually filled with arc extinguishing medium and connected to terminations.

Circuit: An assembly of electrical equipments supplied from same origin and protected against over current by the same protective devices. Categories of circuits are as follows.

Category 1 Circuit: a Circuit (other than a fire alarm or emergency lighting Circuit) operating at LV and supplied from the Distribution Company.

Category 2 Circuit: a Circuit (other than a fire alarm or emergency lighting Circuit) which supplies telecommunications equipment (such as telephones, intruder alarms, data transmission, call bells, etc).

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Category 3 Circuit: a fire alarm or emergency lighting Circuit. Circuit breaker: A device capable of making carrying and breaking normal load currents and also making and automatically breaking, under pre determined conditions abnormal currents such as short circuit currents. It is usually required to operate infrequently although some types are suitable for frequent operation.

Circuit breaker linked: A circuit breaker contact of which are so arranged also make or break all poles simultaneously or in a defined sequence.

Circuit protective conductor (CPC): A protective conductor connecting expose conductive-parts of equipment to the main earthing terminal.

Class 1 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 insulation.

Class2 Equipment: Equipment, in which protection against electric shocks does not rely on basic insulation only, but in which additional safety precautions such as supplementary insulation are provided, there being no provision for the connection of exposed metal work of the equipments to a protective conductor, and no reliance upon precaution to be taken in the fixed wiring of the installation.

Conductor (of a core or cable): The conducting portion consisting of a single wire or of group of wires in contact with each other. For earthed concentric wiring, the term may also denote the metal sheath of a cable.

Conduit: Apart of a closed wiring system for cables in electrical installations, allowing them t be drawn in and/or replaced, but not inserted laterally.

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

Consumer's installation: Wiring and apparatus situated upon the consumer's premises and controlled or installed by him, excluding any switchgear of the supply undertaking which the consumer may be permitted to use.

Consumer's Terminals: The point in the consumer's installation at which the income supply of energy is delivered to that installation.

Core (of a cable): the conductor with its insulation but not including any outer covering for mechanical or other protection. Current carrying capacity of a conductor: The maximum current which can be carried by a conductor under specific conditions without its steady state temperate exceeding a specified value.

Current using equipment: Equipment which converts electrical energy into another form of energy, such as light, heat. Or motive power.

Danger: risk of injury to persons (and live stock where expected to be present from 1. Fire, electrical shock and buns arising from the use of electrical energy. 2. Mechanical move ment if electrically controlled equipment, in so far as such danger is intended to the prevented by electrical emergency switching or by electrical switching for mechanical maintenance of non-electrical parts of such equipment.

Data processing equipment: electrically operated machine units that, separately or assembled in systems, accumulate process and store data acceptable and divulgence of data may or may not be by electronic means.

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Design current of a circuit: The magnitude of the current (r. m s value of ac) to be carried by the circuit in normal service. Direct contact: Contact of persons or livestock with live parts which may result in electric shock. Distribution board: An assembly containing switching or protective devices (e.g. fuses or circuit breakers) associated with one or more out going circuits fed more incoming circuits, together with terminals for the neutral and protective circuit conductors. It may also include signaling and other control devices. Means of isolation may be included in the board or may be provided separately.

Distribution circuit: A category circuit connecting the origin of the installation to: 1. An item of switch gear. 2. An item of control gear 3. A distribution board. • •

To which one or more final circuits or items of current-using equipment are connected.(see the definition of final circuit) A distribution circuit may also be connect the origin of an insulation to an outlaying building or separate insulation, when it is sometimes called a sub- main

Double insulation: Insulation comprising both basic insulation and supplementary insulation. Duct: A closed passageway formed underground or in a structure and intended to receive one or more cables which may drawn in.

Earth: The conductive mass of earth, whose electric potential at any point is conventionally taken as zero. Earth electrode: A conductor or a group of conductors in intimate contact with, and providing an electrical connection to earth.

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Earth electrode resistance: The resistance of an earth electrode to earth. Earth fault current; A fault current which fowls to earth. Earth fault loop impedance: the impedance of the earth fault current loop starting and ending at the point of earth fault. This impedance is denoted by the symbol Z.

Earth leakage current: A current which flows to earth, or to extraneous- conductive parts in a circuit which is electrically sound. This current may have a capacitive component including that resulting from the deliberate use of capacitors.

Earthed concentric wiring: A wiring system in which one or more insulated conductorsare completely surrounded throughout their length by a conductor, for example a metallic sheath, which acts as a pen conductor.

Earth equipotential zone: 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 difference in potential between simultaneously accessible exposed and extraneous- conducive –parts will not cause electric shock.

Earthing: The act of connecting the exposed conductive parts of an installation to the main earthing terminal of an installation. Eatrhing Conductor: a 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 electrical current through a human body or livestock.

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Electrical equipment: An assembly of associated electrical equipment supplied from a common origin to fulfill a specific purpose and having certain co-ordinate characteristics.

Electrical independent earth electrodes: Earth electrode located at such a distance from one another that the maximum current likely to flow through on of them does not significantly affect the potential of others.

Electrode boiler(Electrode water heater): Equipment for the electrical heating of water or electrolyte by passage of an electrical current between electrodes immersed in the water electrolyte.

Emergency stopping: Emergency switching intended to stop a dangerous movement. Emergency switching: Rapid cutting off of electrical energy to remove any un expected hazards to persons, livestock, or property.

Enclosure: a part providing an appropriate degree of protection of equipment against certain external influence and defined degree of protection against contact with live parts from any direction.

Equipotential Bonding: Electrical connection maintaining various exposed conductive parts and extraneous- conductive parts at substantially the same potential.

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

Extraneous Conductive Part: Extraneous- conductive part liable to introduce a potential generally earth potential, and not forming part of the electrical installation.

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Fault: A circuit condition in which current flows through an abnormal or un intended path. This may result from an insulation failure or the bridging of the insulation conventionally the impedance between live conductors or between liv conductors and extraneous- conductive parts at the fault position is considered negligible.

Fault Current: A current resulting from a fault. Final Circuit: A circuit connected directly to current using equipment, or to a socket- outlet or other outlet points for the connection of such equipment.

Fixed equipment: equipment fastened to a support or otherwise secured in a specific location. Flexible wiring system: a wiring system designed to provide mechanically flexibility in use without degradation of the electrical components.

Functional earthing: Connection to earth necessary for proper functioning of electrical component. Functional extra low voltage: Any Extra low voltage system in which not all of the protective measured required for SELV have been applied.

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

Fuse Element: A part of fuse designed to melt when the fuse operates. Fuse link: A part of a fuse, including the fuse element(s), which requires replacement by a new renewable fuse link after the fuse has operated and before the fuse is put back in to service.

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Gas installation pipe: Any pipe not being a service pipe (other than any part of a service pipe comprised in a primary meter installation) or pipe comprised in a gas appliance, for conveying gas for particular consumer and including any associated gas valve for other gas fitting.

High way: a Way means any way(other than a water way) over which there is public passage and includes the highway verge and any bridge over which, the highway passes.

Highway distribution board: A fixed structure or underground chamber, located on a highway used as a distribution point, for connecting more than one highway distribution circuit to a conmen origin, Street furniture which supplies more than one circuit is defined as a highway distribution board. The connection of a single temporary load to an item of street furniture shall not in itself make that item of street furniture in to highway distribution board.

Highway distribution circuit: A category 1 circuit connecting the origin of the installation to remote highway distribution boards or items street furniture It may also connect a highway distribution boards.

Hot Air Sauna: A room in which air is heated to a high temperature and in which the relative humidity is normally low, rising for short period 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 electrical shock.

Instructed person: A person adequately advised or supervised by skilled person to enable him to avoid danger which electricity may create.

Insulation: Suitable non –conductive material enclosing, surrounding, or supporting the conductor.

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Isolation: A function intended to cut off for reasons of safety the supply from the source of electrical energy. Isolator: A mechanical Switching device which provides the function of isolation. Low noise earthing: An earth connection in which the level of conducted or induced interference from external source dos not produce unacceptable incidence of malfunctioning in the data processing or similar equipment to which it is connected. The susceptibility in items of amplitude/ frequency characteristics varies depending on the type of equipments

Luminaire: Equipment which distributes, filters of transform the light form 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: A means for comprising an LSC outlet and an LSC plug providing mechanical support for a luminaire and the electrical connection to and disconnection from a fixed wiring insulation.

LV switch gear and control assembly: A combination of one or more low voltage switching devices together with associated control. Measuring, signaling, protective, regulating equipment, etc., completely assembled under the responsibility of the manufacture with all the internal electrical and mechanical interconnection and structural parts. The components of the assembly may electromechanical or electronic. The assembly may be either type-tested or partially type tested.

Main Earthing Terminal: The terminal or bar to be provided for the connection of protective conductors for functional earthing any, to the means of eatrthing.

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

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Motor caravan: self propelled leisure accommodation vehicle used for touring, designed to meet the requirements for the construction and use of road vehicle. The accommodation may be fixed or demountable.

Neutral Conductor: A conductor connected to neutral point of a system and contributing to the transmission of electrical energy. The term also means the equivalent conductor of an IT or DC system unless otherwise specified in the regulations.

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 the electrical installation. Over current: A current exceeding the rated value. For conductors the rated value is the current carrying capacity. Over current detention: a method of establishing that value of a current in a circuit exceeds a predetermined value for a specified length of time.

Overload current: An over current occurring in a circuit which is electrically sound. PEN Conductor: A conductor combining the functions of both protective conductor and neutral conductor. Phase conductor: A conductor of an ac system for the transmission of electrical energy other than a neutral conductor, a protective conductor or a pen conductor. The term also means the equivalent conductor of a DC system unless otherwise specified in the regulation.

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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- out let or with a connector.

Point (in wiring): A termination of the fixed wiring intended for the connection of current- using equipment. Portable equipment: Electrical equipment which can be moved form one place to another easily while connected to the supply or in the time of operation.

Prospective fault current: The value of over current in a given point in a circuit resulting from a fault of negligible impedance between live conductors having difference of potential under normal operating conditions, or between a live conductors an exposed conductive part.

Protective conductor/ Earth continuity Conductor (ECC): A conductor used for some measures of protection against electric shock and intended for connecting together any of the following parts. • • • • •

Exposed- conductive parts. Extraneous- conductive parts. The Main earthing terminal. Earth electrode(s). The earthed point of the source., or an artificial neutral.

Reduced low voltage system: a system in which the normal phase to phase voltage does not exudes 110 volts and the nominal phase to earth voltage does not exceeds 63.5 Volts.

Reinforced insulation: single insulation applied to live parts, which provides a degree of protection against electrical shock equivalent to double insulation under the conditions specified in relative standard.

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The term single insulation does not implies that the insulation must be one homogeneous piece. It may comprise several layers which cannot be tested singly as supplementary or basic insulation.

Residual Current: the vector sum of the instantaneous value of current flowing through live conductors of a circuit at point in the electrical insulation.

Residual Current device: A mechanical switching device or association of devices intended to cause the opening of the contact when the residual current attains a given value under specified conditions.

Residual operating current: residual current which causes the residual current device to operate under specified conditions. Resistance Area ( for earth electrode only): The surface area of ground( ground and 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 person will come in to contact through a substantial portion of his body with conductive surrounding parts and where the possibility of preventing this contact is limited.

Ring final circuit: A final circuit arranged in the form of ring and connected to a single point of supply. Safety service; An electrical system for electrical equipment provided or warns persons in the event of hazard, or essential to their evacuation from a location.

SELV: An Extra-low voltage which is electrically separated from earth and from other system in such a way that a single fault cannot give rise to the risk of electrical shock.

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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 over current resulting from a fault of negligible impedance between live conductors having a difference in potential under normal operating effects.

Simultaneously Accessible parts: Conductors or conductive parts which can be touched simultaneously by a person or in locations specially intended for them ,by live stock. These parts can be: • • • • •

Live parts Exposed conductive parts Extraneous- conductive parts Protective conductors Earth electrodes

Skilled Person: A person with technical knowledge or sufficient experience to enable instructed persons to avoid dangers that electricity may create.

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

Space Factor: The ratio expressed as a percentage of the sum of the effective overall cross- sectional area of cables forming a branch to the internal cross sectional area of the conduit, pipe ,duct, trunking or channel in which they are installed.

Spur: A branch of ring final circuit.

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Stationary Equipment: Electrical equipment which is either fixed or equipment having a mass exceeding 15 KG and not provided with a carrying handle.

Street furniture: Fixed equipment located on a highway, the purpose of which is directly associated with the use of highway. Street Located equipment: Fixed equipment, located on a high way , the propose of which is not directly associated with the use of the highway.

Supplementary insulation: independent insulation applied in addition to basic insulation in order to provide protection against electric shock in the event of a failure of basic insulation.

Supplier: A person who supplies electrical energy and where electric lines and apparatus used for that purpose are owned otherwise than by that person shall include the owner of those electrical lines and apparatus.

Suppliers works: Electrical lines, supports and apparatus of or under the control of , a supplier used for the purpose of supply, and cognate expressions shall be constructed accordingly

Switch:' A mechanical device capable of making breaking and carrying current under normal circuit condition, 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 that contacts of which are so arranged as to make or break all poles simultaneously or in a definite sequence.

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

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System: An electrical system consisting of a single source of electrical energy and an installation. For certain purpose of the regulations, types of systems are identified as follows. Depending upon the relationship of the source, and of exposedconductive pars of the installation, to earth: • • • • • •

TN system having one or more points of the source of energy directly earthed, the exposed—conductive parts of the installation being connected to the point by protective conductors. TN-C system, in which neutral and protective functions are combined in a single conductor thou out the system. TN-S system, having separate neutral and provided conductors throughout the system. TN-C-S system, in which neutral and protective functions are combined in a single conductor in a part of the system. TT system, a system a system having one point of the source of energy directly earthed, the expose –conductive parts of the installation being connected to earth electrodes electrically independent of the earthed electrode of the source. IT system , a system having no direct connection between live parts and earth, the exposedconductive –parts of the electrical installation being earthed.

Temporary supply unit: An enclosure containing equipment for the purpose of taking a temporary electrical supply safety from an item of street furniture.

Voltage nominal: Voltage by which an insulation is designed. The following ranges o nominal voltages are defined: • •

Extra-low normally not exceeding 50 V ac or 120 ripple free Dc, whether between conductors or to earth. Low normally exceeding extra-low voltage but not exceeding 1000V ac or 1500V c between conductors, or 600 V dc or 900v dc between conductors and earth.

The actual voltage of the installation may differ from the nominal value by a quantity within normal tolerances.

Voltage, reduced: (see reduced low voltage systems).

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Wiring system: An assembly made up of cable or bursars and parts which secure and, if necessary, enclose the cable or bursars.

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Section -3

REQUIREMENT FOR SAFETY 3-1

Good workmanship and the use of proper materials are essential for compliance with these regulations.

All electrical installation works, new and /or addition shall only be carried out by licensed electrical contractors, as authorized by the Sharjah electricity and water authority from time to time. Al materials used in electrical installation shall be of good quality and shall comply as a minimum with the latest relevant recommendations of the International Electro- Technical Commission (I E C) and if this is not available, to the latest relevant British Standard specification (BSS). Materials of other national standards may also be employed provided they are comparable with IEC/BSS. Materials must also be approved by Authority of Electricity and water before use. In case of doubt over acceptability of materials already used; the contractor may be required to produce a copy of SEWA's letter to the material by SEWA.

3-2 Inspection and testing of installations: On completion of an installation or an extension or major alternation to an installation or an extension or major alternation to an installation, tests should be made, with suitable instruments, to verify as far as practicable that the requirements of section 3 have been met that the installation of all conductors and apparatus is satisfactory and that the earthing arrangements are such

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that, in the event of earth fault the faulty circuit or sub-circuit or apparatus is automatically disconnected from supply so as to prevent danger. Contractor shall be required inspection certificates in the prescribed form given in appendix no.6, on completion of the electrical installation and equipments installed there in shall be subject to SEWA's inspection testing and final approval before connecting to the electric supply.

3-3

All electric conductors shall be of sufficient size and current rating for the purpose for which they are to be used.

3-4 All apparatus shall be suitable for the maximum power demanded by the apparatus when it is in use and shall be otherwise so constructed installed and protected as to prevent danger so far as it is reasonably practicable.

3-5 All circuit conductors, including conductors forming part of apparatus shall be either: • So insulated and where necessary further effectively protected. • So placed and safe guard, as to prevent danger. • Every electrical connection shall be of proper construction as regards conductance insulation mechanical strength and protection.

3-6 Every electrical circuit and sub circuit shall be protected against excess current by fuses, circuit breakers, or other similar devices which: •

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Will operate automatically at current values at which are suitably related to the safe current ratings of the circuit and


•

Are of adequate making and breaking capacity and of such construction as to prevent danger from overheating , arcing ,or the scattering of hot metal when they come into operation and as to permit ready renewal of fuse cartridges without danger.

3-7 Where the earth-fault leakage current from a circuit, due to fault of negligible impedance from a live conductor to earthed metal, is insufficient to operate the fuses or circuit breakers of other similar devices provided, so as to cmply with regulation 302(a),the circuit shall be protected against the persistence of earth leakage currents liable to cause danger by an earth- leakage circuit breaker or equivalent device.

3-8

Every single pole shall be inserted in the live conductor only. Any switch connected in the phase or neutral shall be linked switch and shall be arranged to break also all the live conductors.

3-9 All one way switches both singles and double pole, shall be mounted so that the dolly is up when the switch is in the off position. This shall not be considered to be applicable t fireman's switches.

3-10 Where metal work, other than current carrying conductors, is liable to become charged with electricity is such manner as to create a danger if the insulation of a conductor should become defective or if a defect should occur in any apparatus: •

The metal work shall be earthed in such a manner as will ensure immediate electrical discharge without danger of

•

Other adequate precautions shall be taken to prevent danger.

3-11 Effective means, suitably placed for ready operations, shall be provided so that all voltage may be cut off from all apparatus as may be necessary to prevent danger.

3-12 Every electrical motor shall be controlled by an efficient device for starting and stopping, such switch is to be readily operated and so placed as to prevent danger.

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3-13

a) All Apparatus and conductors exposed to whether, corrosive atmosphere, or other adverse condition, shall be so constructed or protected as may be prevent danger arising from such exposure.

b) Where a conductor or apparatus is, or is likely to be , exposed to flammable surroundings or an explosive atmosphere, it shall be protected by a flameproof enclosure or be otherwise so designed and constructed as to prevent danger.

3-14 Conductors and apparatus operating at voltage between conductors or to earth and exceeding 250 volts shall either: • •

Be completely enclosed in earthed metal, which is electrically continues and adequately protected against mechanic at damage or; Be so constructed, installed and protected as to prevent so far as reasonably practicable land to comply with the various sections of these regulations.

3-15 In situation which may be normally wet or damp. where electrical apparatus is present and might give rise to danger, and where there are substantial exposed metal parts of other service (such as gas and water pipes, sinks, and baths),the earth continuity conductor of the electrical installation shall be effectively connected, electrically and mechanically, to all such metal parts and to any exposed metal work of the electrical apparatus which is required by regulation 394 to be earthed.

3-16 a) Electrical, equipment shall be firmly secured to the surface on which it is mounted. Wooden plugs driven into holes in masonry concrete or plaster shall not be used. b) Electrical equipment shall be installed so that wall or other obstructions do not prevent free circulation of cooling air.

3-17 No addition, temporary or permanent shall be made to the authorized load of an existing installation, unless it has ascertained that the current rating and the condition of any existing conductors and apparatus (including those of the supply undertaking) which will have to carry the additional load are also adequate for the increased loading. Any addition shall take place only after approval of the proposal and inspection of the additions by SEWA.

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3-18 Where for construction purposes or otherwise. A temporary supply is required; the temporary electrical installations shall comply as a minimum, with all the safety requirements and shall in each case be to the approval of the SEWA. •

Every temporary installation shall be in the charge of a competent person who accepts full responsibility for the installation, its use and any alternations. The name and designations of this person must be permanently and prominently displayed at the main switch position. Failure to observe this requirement may lead to disconnection of supply.

3-19 Permission for every installation of discharge (cold cathode) lighting shall be individually obtained from SEWA.

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Section -4

SUBSTATIONS. SERVICES ARRANGEMENT, AND DISTRIBUTION BOARDS 4-0

Substation

4-1

SEWA shall be responsible for making the decision regarding requirements of substation for provision of supplies to any new project or development no charges to the requirements given may remade without prior written agreement from the SEWA. The substation will be constructed to drawings provided by SEWEA and no equipment will be installed in the substation before structure has been inspected and approved by the SEWA.

4-2

Where an LV switch room is located immediately adjacent to a trans former room or transformer space, no door shall be provided in the connecting wall. Only on the transformer side by means of hasp and staple. The authority of electricity and water will provide the padlock for this door. Under no circumstances will this door be able to be opened from the LV switch room side. This door shall be only used by SEWA authorized personnel as and when required.(optional condition subject to SEWA approval).

4-3

Where LV switch room is located far away from the substation and is supplied from the network at low voltage via a single multi core cable, access to this room is also required by SEWA personnel the same method of locking the door shall be used as stated above. The individual key for this padlock will be handed over to the consumer. SEWA will have access by means of a master key system used by authorized personnel.

4-4

The main door of the LV switch room will be of sufficient size to allow removal of the switch board in the form of individual cubicle units.

4-5

Sub main cables and final circuit wiring shall not be permitted to pass through transformer and HV rooms. This requirement shall apply to cables run above floor level and below floor level in a cable trench this shall not apply to the

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final wring installed for lighting and power within these rooms or in the case of circuits associated with protection of equipment within those rooms.

4-1

Low Voltage Switch Rooms

4-6-1 All low voltage main switch room shall be air conditioned by means of extending the air condition duct work system supplying the complete building or mounted self contained air conditioning shall be sized to limit the room temoperature to maximum of 30c under maximum load conditions. Where individual room A/C intervals. The switch must be thermally insulated.

4-6-2 Services associated with air conditioning water, drainage, and telephone shall not be allowed to pass through. HV Switch rooms, transformer room or main LV switch rooms

4-6-3 The location , size, design and layout of the LV switch room must be approved by SEWA before construction of the building. Due consideration must be made of the dimension of switchgear to be installed when the design is carried out. It must appreciated that dimensions similar equipment vary considerably. If if clearance are not sufficient when the switch gear is installed into the building, supply will not be made until all clearance requirements are met.

4-6-4 The minimum size of transformer room if contains one transformer shall not be less than 4.5 meters with door facing to road side, incase of more transformers SEWA is responsible to decide required space.

4-6-5 The minimum size of LV switch room where an LV panel to be connected to transformer is to be located is 2.66x4.5 meters

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4-7 LV Main switch boards –cubicle 4-7-1 Main Switch board connected to a transformer of 500 KVA and shall be of cubicle construction.

4-8 SEWA In coming Supply Cable 4-8-1 Where the incoming supply cables are laid in a trench to the main switch board then that trench shall be used only for those cables in any installation, the main incoming supply cables to the main switch board shall be totally segregated from any other consumer cable. Suitable glands shall be provided on cubicle main switch boards for the support of the incoming supply cable. These cable glands shall be fixed to a metal plate of non ferrous material.

4-8-2 Where the main switch board is supplied directly from the secondary of the transformer and no cut out is installed; the maximum length permitted for these cables from transformer to the main switch of the consumers main LV switch board shall be 10 meters.

4-8-3 General approval: All main switchboard details shall be submitted to SEWA for prior approval before the switch board is manufactured. Each manufacturer of cubicle switch board shall supply all relevant authorized test certificates regarding the fault level capabilities of the type proposed switch board. These test certificates must be provided by a certified independent testing authority and not by individual manufacturer.

4-8-4 Protection curves showing the time/ current tripping characteristics of all main switch fuses MCCBs and ACBs shall be submitted to the SEWA together with the manufacturers working drawings and technical submittal.

4-8-5 Switch board panel Materials: switchboard panels shall be constructed wholly of durable no flammable non hygroscopic, Vermin proof material and all insulation shall be permanently highly electric strength and insulation resistance.

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4-8-6 arrange ment of apparatus on main switch board: All Apparatus shall be so placed on a switchboard to ensure ample room for safe and effective operation and handling.

4-8-7

Labels: The main distribution board shall be labeled systematically in English to describe the designation of the incoming and outgoing switching devices as referred in the drawings,. A main label shall be fixed to the front face of the main distribution board. The label shall be of special while PVC material front engraved for the desired text. The text shall be black in color. The label shall be fixed to the door using a special PVC rivets. Each metallic and polycarbonate shrouds shall be provided with engraved warning labels indicating 'Danger-415 Volt Live Busbars Inside –Isolate Main Supply Before Opening This Cover' at the front face. All such warning plates shall be riveted to the shroud plates. Permanent labels shall be provided inside the main distribution board for phase identification of the incoming and outgoing devices identification labels shall be provided for neutral and earth connections. A drawing pouch/ pocket shall be provided inside each main distribution board and approved load schedule (laminated) and as built control centre shall be provided. Every cubicle panel shall bear a permanently affixed label, marked durably and fixed on the incoming main switch panel giving the following information. a) Manufacturers name and address. b) Sufficient indication to enable the panel to be identified for the purpose of obtaining information, etc from from the manufacturer. c) Rated operating Voltage, current and frequency. d) Short circuit rating for a period of three seconds.

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e) Class of switch board in accordance with BS5486 Part IEC 439.

4-8-8 Main Switches The main switch or switches of every installation shall be marked as such and shall be identifiable from other switch gear by grouping coloring or other suitable means, such as to render (or them) easily located in an emergency where there is more than one main switch in any building each shall be marked to indicate which installation or section of installation it controls.

4-8-9

In a cubicle main switchboard each main controlling switch shall be located in tits own section, completely segregated from all other parts of the switch board with front access for operation.

4-8-10 Where a medium voltage switch board is connected directly to the low voltage winding of the transformer the main controlling switch or switches shall be the totally withdraw able type air circuit breaker type

4-8-11 The main switch shall be so located that only the main incoming cables to that switch are installed in that section. 4-8-12

Al main switches on main switch boards )of either cubicle type or otherwise) shall be located that a minimum distance of 700mm exists from the finished floor level to the bottom of the switch or connection straps, which ever is less.

4-8-13

To ensure discrimination of circuit breakers on individual circuits. The rating of the main circuit breaker is to be at least twice that of largest circuit breaker controlling an out going circuit.

4-9

Metering:

4-9-1 Provision shall be made in cubicle main switch boards for the installation of SEWA metering equipment located in separate incoming section cubicle or above the main switch.

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4-9-2 Current transformers of class 21 metering type shall be installed on all type of main switch boards where the load dictates metering by means of current transformers. There shall be located on the main bus bars immediately after the main incoming switch where the complete installation is to be metered at source.

4-9-3 Otherwise , where metering is carried out remotely, as in residential accommodation, landlords located on the bus bar immediately before the landlords distribution section. Removable links 250mm long shall be provided in the main bus bar of each phase to enable easy maintenance and replacement of current transformers.

4-9-4 Where metering CTs are to be installed in a cubicle main switch board they shall be supplied and fitted by the panel manufacturer to comply with SEWA requirements. The following standard sizes of CTs are used:

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200/5

5 VA

300/5

5 VA

400/5

5 VA

500/5

5 VA

600/5

5 VA

800/5

5 VA

1200/5

5 VA

1600/5

5 VA

2000/5

5 VA

2500/5

5 VA


4-9-5 All CTs installed in cubicle switch board by manufacturer shall be pre wired to ten way terminal block located in the metering compartment using color coded wiring.

4-9-6 Each kilowatt hour meter installed by SEWA shall be mounted on fir proof plywood base board having minimum dimensions of 300 mm x 300 mm x 12 mm thick. This plywood mounting board shall be supplied by the panel manufacturer.

4-9-7 All cubicle main switch board shall be fitted with three, maximum demand reading ammeter ,together with a voltmeter reading both phase to neutral and phase to phase voltages by means of a selector switch. All ammeter connections shall be made from current transformers located after the main switch or switches and shall be totally independent from the current transformers installed for the KWH consumption meters.

4-9-8 All small wiring for controls, voltmeter suppliers, etc that originates from the main and sub main bus bars shall be connected to the bus bars by means of busbar mounted HRC cartridge fuses suitable rated for their intended use. The maximum size of fuse used shall not exceed 20 Amps.

4-10 Restricted earth fault protection: A restricted earth fault protection relay shall be installed on each incoming supply to a main switch board and shall interrupt the fault by isolating relevant circuit breakers. As far as possible the protection Cts shall be located on the main horizon bus bars. This protection is designed to look back towards the secondary winding of the supply transformer and all small control wiring and other current transformers shall be located so that they are protected by this relay. Current transformers to be class X or equivalent. The restricted earth fault relay shall be installed to trip both LV and the SEWA HV switches under earth fault condition and it is the consumer's responsibility to provide a suitable interconnecting cable for this purpose. This setting of the protection relays are to be agreed by SEWA and commissioning tests witnessed by SEWA. LV tripping shall be by means of v.d.c system with battery and charger supplied and maintained by the consumer.

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4-11 Sealing of apparatus: All apparatus , main switches, busbars, sub main switches, rising main distribution systems on the supply side of any SEWA meter shall have provision for sealing that apparatus by SEWA. The removable lid section of rising main busbar trunking shall have provision for sealing through the entire route length.

4-12 Busbars: 4-12-1 The busbar system shall be designed as per the pre- defined guidelines provided by the original manufacturer. The busbar system shall be type tested by the manufacturer at reputed laboratory for short circuit withstand capacity. The neutral and earth busbars shall also be type tested for the short circuit withstand capacity. the fault level rating of the busbar system shall be as per the drawings however the minimum short circuit with stand capacity shall be 50 KA RMS for 1 second. Neutral busbar shall be able to with stand a thermal stress of at least 60 % corresponding to the main phase busbar rated short circuit withstand capacity.

4-12-2 The busbar shall be a high graded electrolytic tin plated copper (with 99.9% conductivity)rectangular and rigid construction. The phase busbar and neutral busbar shall be arranged systematically in busbar chamber/alley. The busbar shall be color sleeved throughout the length for phase identification (except for the distribution busbars of the withdraw able sections). The busbars shall be shrouded completely using metallic partitions and /or poly carbonate shrouds as applicable. The busbar assembly shall be shrouded (at least by IP 20) by shrouds so that no live parts are accessible. Phase identification shall be done systematically. Use of bakelite sheets for shrouding will not be permitted.

4-12-3 The busbar system shall be supported adequately at regular intervals as per manufacturer guidelines based on the type test results on a specially designed busbar supports. The support shall be independently fixed to structure to strengthen the busbar arrangement. Wherever required additional intermediate supports shall be provided between busbars. All vertical droppers shall also be adequately supported as per manufacturer guide lines and test results. The distribution busbar shall be connected to main busbar by suitable sized and graded bolts and nuts and contact washers. Clamp type arrangements for connections will not be permitted. Connections to the switching device to the main or distribution bus bar shall be carried out of rigid busbars of adequate and standard sizes. it shall be possible to replace the switching devices with efferent rating with same frame sizes without changing the interconnection busbars.

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4-12-4 Distance between busbars supports for busbar system and the distance between different phases of busbar system shall b as per manufacturer guidelines based on the type test results.

4-12-5 The main busbars shall be accommodated on a separate busbar chamber running horizontally at the top or bottom or middle of the panel. Main busbars running behind the functional units (the switching device mounting plates ) will not be permitted. Distribution busbars are permitted at the back of switching device compartments only where withdraw able versions are used.

4-12-6

The dimension of the busbar system shall be as per the rated current of the main switching device, the short circuit current, the maximum rated permissible temperature at permanent operation and ambient temperature around the busbars. The section of the busbar shall be supported by calculations and recommendations from the original manufacturer. The main phase and neutral busbars shall be of same size through out the panel irrespective of the rating and load distribution. Each busbar shall be of half the size of phase busbars. Several copper bars may be used for each phase and neutral, however such parallel running busbars of each phase / neutral shall be spaced evenly with a minimum gap of 5 mm between the bars. Busbars system shall be standardized with 5 mm thick main busbars and interconnection bus bar for better heat dissipation.

4-12-7

Where ever specified as form- 4 construction, the neutral busbar shall run along with the phase busbar and shall outgoing switching devices neutral connection terminal shall be provided with switching device compartment. Neutral busbar running at bottom or in the cable chamber/ alley will not be accepted in case of form-4 construction.

4-12-8

Earth busbar shall be running throughout the panel fitted directly on to the structure for connection of the protective conductor to provide equipotential bonding of exposed conductive parts. Earth busbar shall be located at the bottom of the panel and in the cable chamber/ alley to facilitate easy connection of protective conductor.

4-12-9

Hardware's used for busbar connection shall be zinc plated yellow passivated / bi-chromate steel of 8.8 grade. Tightening of busbar shall be done as per manufacturer recommendations and predetermined guidelines using calibrated torque wrenches.

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4-12-10

Neutral and earth busbars: All cubicle main switch board shall be complete with a separate earth bar running the full length of the panel. The current carrying capacity of this neutral bar shall be not less than of the SEWA incoming supply conductor and shall be of rectangular cross section, hard drawn tin copper.

4-12-11

All cubicle main switch boards shall be complete with a separate earth bar running the full length of the panel. The minimum size of this earth bar shall be 300 mm2 .hard tin copper.

4-12-12

A removable earth o neutral bar link shall be installed in all switchboard and the minimum size of this bar shall be 300 mm sq and of rectangular cross-section. The link shall be between the earth and neutral conductor, leaving sufficient space for mounting of a restricted earth fault protection neutral transformer, between the point attachment of link and the termination.

4-12-13

Under no circumstances will a common earth/ or neutral bar be accepted. Earth bars and links shall be so located and mounted that easy access of there is not obstructed by the structure or wiring of the switchboard and so that all outgoing neutral and earth conductors can be readily and safely connected and disconnected without moving other cables or disconnecting supply to the switch board.

4-12-14

Clearance from bare conductors and live parts: all bare conductors and bar live parts of a switch board shall be rigidly fixed in such manner that a clearance of at least 20mm is maintained between such conductors or parts of opposite polarity or phase and between such conductors or parts and any material other than insulating material to allow clearance to be reduced below 20 mm will not be permitted.

4-12-15 4-12-16

Links: links shall be marked to indicate whether they are live or neutral.

Cables interconnections: where PVC insulated cable are used for the interconnection of switch boards, these shall be terminated at the busbars by means of bolt fixing, crimp or soldered type cable lugs.

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4-12-17

Main and sub main switch fuses: on main switchboards the interconnections between the main busbars and the out going main switches of 400 AMP and above shall be of busbar type only. Where switch fuses are to be installed for either the main or sub main circuits on any switch board, these units shall be de3signed for fast make and break contacts any switchboard, these units shall be designed for fast make and break contacts . this shall be achieved by means of mechanical spring arrangements where prescribed torque must be exerted before the switch makes or breaks its contact. For every fuse and circuit breaker there shall be provided on or adjacent to an indication of its intended nominal current as appropriate to the circuit it protects. Labels or other suitable means of identification, shall be provided to indicate the purpose of switchgear and control gear. Such labels are to be secured by screws. Where lids or doors in the switchgear enclosure can be opened b without the use of a tool or key, all live conductive parts which are accessible if the lid or door is open shall be behind an insulating barrier which prevents person from coming into contact with those parts this insulating barrier shall be provided with degree of protection at least IP2X and be removable only by use of a tool.

4-12-18

Miniature circuit breaker distribution boards shall not be installed. For main or sub main cable distribution, neither shall miniature circuit breakers be installed fro any purpose as part of a cubicle panel nor shall rewirable fuses be permitted.

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4-12-19

Fault levels:

Where the main switchboard in any installation is connected directly from the low voltage side of transformer in an adjacent substation without any distribution cut out, the complete consumer main switchboard shall be manufactured to comply, in total with the following fault level: Short circuit rating of Main Switchboard Supply Transformer

(for duration of 3 seconds minimum)

Rating KVA

(KA)

(MVA)

250

35

18

500

45

18

1000

55

31.5

1500

65

40

The above rating shall be applied to the whole switch board including main switch or switches, main busbars, interconnection. Busbars and all outgoing sub main switch fuses, fuse switches, circuit breakers, contractors, and other equipment used in the main switch board. Where increase of load requires that a transformer rated less than 500 KVA is changed for one of 500 KVA or greater rating it will be necessary for the cubicle panel also to be changed.

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Where it is proposed to install circuit breakers for all or any of the outgoing sub main circuits, then if these units are not rated to the above fault levels, fault current limiting HRC fuses shall be installed, in series with the circuit breakers controlling the outgoing circuit, so as to achieve the required fault rating. The ratings and characteristics of fault current limiters, where fitted, shall be also selected, in relation to the available short circuit currents and the rating and characteristics of the associated protective or other equipment, as to limit the instantaneous fault current carried by the latter equipment to a value within the capacity of that equipment. The selection of fault current limiters shall also be such that they will not operate under overload, as distinct from short circuit conditions. See table No: 1 for acceptable list of fault current limiters that may be used. Where fuses are used as fault current limiters, the word fault current limiters shall be marked on or adjacent to, all such devices in a legible and permanent manner. Fault current limiters may be connected either on the supply side, or on the load side, of any associated protective equipment, fault current limiters need not be controlled by a switch and subject to the provision of ready and safe access, they need not be mounted on the front of the switch board. Provided that, where fault current limiters mounted in any position other than on the front of the switch board. The existence of the position of such limiters shall be indicated in in a clear and permanent manner on the front to the switch board.

4-12-20

Any equipment which may retain dangerous charges after having been isolated must be fitted with device for discharging. If this is non automatic, the discharge device must be clearly labeled.

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4-12-21

De-rating factors due to high ambient temperatures affecting miniature circuit breakers, moulded case circuit breakers and air circuit breakers. All circuit breakers of any type shall have a de-rating factor applied to their manufactured current rating. This shall apply without exception, regardless of where or how they are installed, unless the circuit breaker has already been calibrated by the manufacturer for 50 degree C when no de-rating shall apply. The de-rating shall be to 805 of the current rating stated by the manufacturer.

4-12-22

Only item directly associated with the provision of supply and direct control of sub circuits shall be permitted on a cubicle switchboard. These items shall include SEWA and generator main supply circuit breakers and changeover equipment, busbars, links meters and associated wiring, protection devices, out going switch fuses or circuit breakers and power factor correction equipment.. The inclusion, within the cubicle panel construction, of switchgear operating, and indicating devices operated by items remote from switch board, where the circuit from the cubicle panel supplying these items remains live, regardless of the operation of the aforementioned switchgear and indication, will not be permitted. Any such equipment must be installed in a purpose made panel which is physically separate from the cubicle panel.

4-12-23

Every switch board shall be so arranged that safe access may be readily obtained for the purpose of removing , or replacing any conductor of piece of equipment forming a portion of the switch board. Where a switchboard is of such deign that persons must enter the space behind the switch board for the aforementioned purposes, provisions shall be made for ready and safe access to and exit from such space. The access shall not be less than 600 mm wide and 2000 mm high. Where a switchboard incorporates rack-out switchgear, doors or hinged panels at the front, there shall be a clearance of not less than 900 mm between any wall or immovable structure and the switchgear, doors or hinged panels when in the racked out or open position.

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For switchboard completely enclosed in a metal cabinet, or cubicle fitted with doors for the purposes of access , as required above, or cubicle switch board shall be spaced at such a distance from the wall or immovable structure that ready access is available in front of the doors and such that the doors may be fully opened. The doors shall be so arranged that when opened on any position the minimum clearance between the door and the wall or immovable structure shall be 900 mm where the length of the switch board does not exceed 4 meters. Where a switch board of this type is more than 4 meters in length the minimum space behind the switch board shall be 1.2 meters with the largest door in the open position. Access shall be from both end of the switch board. Where switch board are provided with unhinged removable metal panels for the purpose of access as required above, such panels shall be provided with means of support, such as studs, or not less than two fixed pins ir other suitable means, to retain the panels in position after the removal or fixing screws or bolts, etc. where the area of panel exec 0.75 sq mm handles or other suitable devices shall be provided to facilitate the above paragraph.

4-12-24

Hinged panels: hinged switch board panels , metal switch board surrounds or enclosures shall be so constructed that the panel and the equipment mounted thereon will be adequately supported without undue distortion when the panel is in any position. For hinged panels, the hinging may be on the vertical edge provided that the width of the panel is not greater than 1.5 times its height. Switchboards complying with this cause may be grouped together provided that the removal or hinging of a panel shall not be relied upon to give access to any other panel.

4-13

Access to passage ways: unless the switch board is located unless the switch board is located in a switch room, to which only authorized persons have access, the space behind the switchboard shall be enclosed by a substantial wall or screen at least as high as switchboard panels, and access to this space, as required above, shall be provided by lockable doors, arranged to open outward and shall be capable of being opened from within without the use of key.

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4-14 All clearance given in this section are to be measured I with all windows and doors in the closed position. 4-15 Alternations to or replacement of switch boards: If , in the opinion of the inspection Authority of SEWA the apparatus comprising the switchboard or the lay out and arrangement of the switchboard does not provide for the safe and effective control of the circuits and apparatus to be connected there to or supplied there from, it shall be replaced by a switchboard complying with the requirements of these regulations, safe and effective control of the circuit and apparatus. The costs of such alterations or replacement will not be the responsibility of SEWA.

4-16 Supplies form SEWA Network: 4-16-1

Up to 400 Amp Capacity: service to general residential, small commercial and small industrial premises shall be provided to an approved design of service cabinet at the boundary of the property concerned supply will be made available by this method up to a service capacity of approximately 400 Amps and will normally be used for single uccupied premises only.

4-16-2

Service cabinet will normally be mounted in a wall facing a street and as closed as possible to the LV main which will supply it. SEWA therefore reserve the right to determine the location of the service cabinet.

4-16-3

The supply is to be provided by SEWA to the consumer at a wall mounted service cabinet, the consumer shall responsible for provision of a suitable cable to provide connection between the service cabinet and the main switchboard within the building.

4-16-4

The cable is to be installed within a 150 mm duct which will have, at the service cabinet and main switch board, an easy bend. The duct shall be installed in accordance with SEWA regulation and a correctly sized earth wire must be installed with cable installed with the cable. At the main switch board position the arrangement of equipment shall be as sketch 3. Cable lengths and sizes noted lengths and sizes noted below are related to a horizontal length of 15 m with two meters at each end for termination into relevant switchgear. The total lengths is thus 19 m. in the case of lengths exceeding 19 m, calculations must be made to ensure that the maximum volt drop at any part of the installation does exceed 2.5 5 of the supply voltage. The length of the cable is to be indicated on drawings submitted for approval.

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Installation Demand Cable type(19m length) 2C PVC/SWA/PVC for single

40A

80 A

100A

Phase service only

16mm2

-

-

4C PVC/SWA/PVC

16mm2

35mm2

50mm2

$C XLPE/SWA/PVC

16 mm2

25mm2

35mm2

Size of cable differing from these noted above may be used with the prior agreement of SEWA.

The minimum fault level for any supply position connected by means of a SEWA cut-out shall be 35 KA for duration of 3 seconds.

4-17 Above 400 Amp Capacity: if the demanded load exceeded 200 KW or the SEWA LV network is far away from the premises the supply will be through SEWA HT network in this case full co-ordination to be made with SEWA to specify the location of substation within the boundary of premises the details and dimensions of substation room is shown in the appendix.

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4-18 General recommendation for switch gear installation: 1. Switchboard shall be installed in suitable places which shall be totally dry. No bathrooms is allowed above electrical rooms. 2. Where the incoming SEWA supply terminates in a cut out and a service cabinet is not used then the contractor shall install a 100 mm dia minimum size pipe, with draw wire from the main switch board to the boundary wall. This pipe shall be run at 600 mm below the ground level. 3. All switch boards shall be placed that the switchboard and access there to is not obstructed by the structure or contents of the building or by fittings and fixtures within the building. A distance of not less than 900 mm shall be provided and maintained on front of every switchboard for the purpose of safety and effectively operating and adjusting all equipments mounted thereon. 4. in the case of cubicle type panel with rear access, there shall be a clearance of minimum 900 mm at the rear of the panel which shall be constructed in accordance with section 410. 5. Switchboards shall not be installed in cupboards used for storage purposes. 6. A switchboard shall not be installed in any of the following locations. a) kitchen b) Bathroom c) Toilet d) Above sinks e) Below a staircase where there is less than 2 m vertical distance from the floor to the ceiling.

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f) In an external location except in a purpose made enclose approved by ministry of Electricity and Water. g)In an area below street level except as individually approved by ministry of Electricity and Water. 7. The door of a switch room in which switchboard or switchboards are located shall be lockable and arranged to open outward and shall be capable of being opened from the inside with out the use of the key. Such doors shall be not obstruct any area into which they may open. 8. in a multi occupancy building, adequate illumination shall be provided in the vicinity of the service intake and switch gear. Self contained emergency lights, switched on automatically in the event of failure of supply shall be provided and be capable of, illuminating the area for a period of three hours. 9. In single occupancy buildings installation of such lights are recommended.

4-19 Distribution Boards: 4-19-1 Distribution shall comprise miniature circuit breakers, moulded case circuit breakers and earth leakage circuit breakers.

4-19-2 Each distinction board shall be protected by its own individual switch,

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Section -5

EARTHING ARRANGEMENTS AND PROTECTIVE CONDUCTORS

5-1 General. The performance of the earthing arrangements shall satisfy the safety. And functional requirements of the electrical installation.

5-2 Connection to earth 5-2-1 Earthing arrangements: The earthing arrangements may be used jointly or separately for protective or functional purposes according to the requirements of the installation. 5-2-2 The selection and erection of the equipment of earthing arrangements shall be such that. 1. The value of earthing resistance is in accordance with the protective and functional requirements of the installation and expected to be continuously effective. 2. Earth fault currents and earth leakage currents can be carried without danger , particularly from thermal , thermo mechanical and electro mechanical stresses. 3. it is adequately robust or has additional mechanical protection appropriate to the assessed conditions of external influence.

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5-3 Precaution shall be taken against the risk of damage to other metallic parts through electrolysis. 5-4 Earth electrodes. 5-4-1 The following types of earth electrodes may be used: 1. Earth rods or pipes. 2. Earth tapes or wires. 3. Earth plates. 4. Earth electrodes embedded foundations. 5. Metallic reinforcement of concrete. 6. Metallic water pipe systems. 7. Other suitable underground structure the efficacy of any earth electrode depends on local soil conditions and one or more earth electrodes suitable for the soil conditions and value of earth resistance required should be selected the value of earth resistance of earth electrode may be calculated or measured.

5-4-2 The type and embedded depth of earth electrodes shall be such that soil drying and freezing will not increase the earth resistance of earth electrodes above the required value.

5-4-3 The material used and the construction of earth electrodes shall be such as to withstand mechanical damage due to corrosion. 5-4-5

Page 54

Metallic water pipe systems may be used as earth electrodes provided that the consent of the distributor of the water is obtained and that suitable arrangement exists for the user of the electrical installation to be warned of any proposed changes in water pipe systems.


5-4-6

Lead sheaths and other metallic covering of cables not liable to deterioration through excessive corrosion may be used as earth electrodes provided the consent of the owner of cables is obtained and suitable arrangements exist for the user of electrical installation to be warned of any proposed changes to the cable that may be affect its suitability as an earth electrode.

5-5

Earth conductors

5-5-1

Earthing conductors shall comply with clause 5.6.1 and where buried in the soil their cross sectional areas shall be in accordance with table 5.1A.

Table 5.1.A conventional cross sectional areas of earthing conductors Mechanically protected

Mechanically unprotected 16mm2 Cu

Protected against corrosion

As required clause 16mm2 Fe 25 mm2 Cu

Protected against corrosion 50mm2 Fe

5-5-2 the connection of an earthing conductor to an earth electrode shall be soundly made and electrically satisfactory where a clamp is used it shall not damage the electrode or the earthing conductor.

5-6

Main Earthing Terminal or Bars

Page 55


5-6-1

In every installation a main earthing terminal or bar shall be provided and the following conductors shall be connected to it earthing conductors protective conductors main equipotential Bonding conductors functional earthing conductors required.

5-6-2

Means shall be provided in an accessible position for disconnecting the earthing conductor such means may conveniently be combined with the main earthing terminal or bar to permit measurement of the resistance of the earthing arrangements this joint shall be disconnect able only by means of a tool , shall be mechanically strong and ensure the maintenance of electrical continuity .

5-7-1

Protective Conductors

1-1-1 Minimum cross sectional areas The cross sectional area of protective conductors shall either be • Calculated in accordance with sub clause 5.7.2 • Selected in accordance with sub clause 5.7.3 In both cases sub clause 5.7.4 shall be taken into account. Note :The installation should be so prepared that equipment terminals are capable of accepting these Protective conductors.

Page 56


5-7-2

The cross sectional area shall not be less than the value determined by the following formula (applicable only for disconnecting times not exceeding 5s) S = √ (I 2*t)/k Where: S= cross sectional in square millimeters. I=Value (a.c r.m.s of fault current for fault of negligible impedance which can flow through the protective device in amperes) T=operating time of the disconnecting device in seconds.

Note: - Account should be taken of the current limiting effect of the circuit impedance and the limiting capability (Joule integral ) of the protective device . Value of k for protective conductor in various use or service are as given in table 5.7.A, 5.7.C , 5.7.D , 5.7.E If application of the formula produces non standard sizes, conductor of the nearest higher standard cross sectional area shall be used.

Note: - It is necessary that the cross sectional area so calculated be compatible with the condition imposed by Fault loop impedance, Maximum permissible temperatures for joints should be taken into account values for mineral insulated cables are under consideration .

Page 57


Table 5.7.A: Values of k for insulated protective conductors not incorporated in cables or bare protective conductors in contact with cable covering Insulation of protective conductor of cable covering PVC

XLPE EPR

Butyl Rubber

160C

250C

220C

Copper

143

176

166

Aluminum

95

116

110

steel

52

64

60

Final temperature Material conductor

Note: The initial temperature of the conductor is assumed 30 C

Page 58


Table 5.7.C: Values of k for protective conductors as a core in multi core cables insulation material PVC

XLPE EPR

Butyl Rubber

Initial temperature

160C

250C

220C

Final temperature

160C

250C

220C

Copper

115

143

134

Aluminum

76

94

89

Material of conductor


Page 59


Table 5.7.C: Values of k for bare conductors where there is no risk damage to any neighboring material by the temperatures indicated Visible and in restricted area

Normal condition

Fire risk

Temperature max. Copper k

500 C 228

200 C 159

150 C 138

Temperature max. Aluminum k

300 C 125

200 C 105

150 C 91

Temperature max. Steel k

500 C 82

200 C 5850

150 C


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5-8-1 The cross sectional area of the protective conductor shall not be less than the appropriate value Shown in table 5.8.A in this case checking of compliance with clause 5.7 is not necessary If the application of this table produces non standard size conductor having the nearest standard Cross sectional areas are to be used. Table 5.8.A

Cross sectional area of phase Conductors of the installation S (mm2 )

Minimum cross sectional area of the Corresponding protective conductor SP (mm2 )

S≤ 16

S

16 < S ≤ 35

16

S> 35

S/2

The value in table 5.8.A is valid only if the protective conductor is made of the same metal as the phase conductor. if this is not so the cross sectional area of the protective conductor is to be determined in a manner which produces a conductance equivalent to that which results from the application of table 5.8.A . The cross sectional area of every productive conductor which doesn’t form part of the supply cable or cable enclosure shall be in any case not less than a) 2.5 mm2 if mechanical protection is provided b) 4.0 mm2 if mechanical protection is not provided.

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Types of protective conductor Deleted

5.9.1

Protective Conductors may comprise:• Conductors in multi core cables • Fixed bare or insulated conductors • Insulated or bare conductors in common enclosure • Metal covering ,for example , the sheaths and armouring of certain cables • Metal conduits or other metal enclosures for conductors • Certain extraneous conductor parts.

5-9-2

Where the installation contains enclosures or frames of factory Built assemblies or metal –enclosed bus bar trunking system (busway) the metal enclosure or frame may Be used as protective conductors if they simultaneously satisfy the following three requirement:

5-9-3

a) Their electrical continuity shall be achieved in such manner as to ensure protection against mechanical or electromechanical deterioration b)

Their conductance shall be at least equal to that resulting from the application of clause 543

c)

They shall permit the connection of the protective conductors at every predetermined tap-off point.

5.9.4 The metallic covering including sheaths (bare or insulated) of certain wiring in particular the sheaths of Mineral –insulated cables, and certain metallic conduits and trunking for electrical purpose (types under consideration) may be used as protective conductor for the corresponding circuits if they satisfy Both purpose shall not be used as a protective conductor.

Page 62


5-9-5

Extraneous conductive parts may be used as protective conductor if they satisfy all the following four Requirement. a) Their electrical continuity shall be assured, either by construction or by suitable connection, in such a way as to be protected against mechanical, chemical or electromechanical deterioration. b) Their conductance shall be at least equal to that resulting from the application of the clause 543 C) Unless compensatory measures are provided, precautions shall be taken against their removal d) They have been considered for such a use and, if necessary , suitably adapted . The use of metallic water pipe is permitted provided the consent of a person or body responsible for the water system is obtained. Gas pipe shall not be used as protective conductor.

5-9-6 Extraneous conductive parts shall not be used as PEN conductors. 5-9-7

Preservation of electrical continuity of protective conductors.

5-9-8

Protective conductors shall be suitably protected against mechanical and chemical deterioration and Electrodynamics forces.

5-9-9

Joints of protective conductors shall be accessible for inspection and testing except in compound-filled Or encapsulated join

5-9-10 No switching device shall be inserted in the protective conductor , but joints which can be disconnected For test purpose by use of a tool may be provided.

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5-9-11

Where electrical monitoring of earth-continuity is used the operating coils shall not be inserted in Protective conductors.

5-9-12 exposed conductive parts of apparatus shall not be used to from part of the protective conductor for Other equipment except as allowed by sub-clause 5.9.5.

5.10

Earthing and protective conductors for fault –voltage –operated protective devices.

5-10-1 An auxiliary earth electrode shall be provided electrically independent of all other earthed metal for Example, Constructional metalwork, pipes, or metal-sheathed cable .This requirement is considered to be fulfilled If the auxiliary earth electrode is installed at a specified from all other earthed metal (value of distance Under consideration).

5-10-2 The earthing conductor leading to the auxiliary earth electrode shall be insulated to avoid contact with The protective conductor or any of the parts connected there to extraneous conductive parts which are or may be in contact with them. Note: this requirement is necessary to prevent the voltage sensitive element being inadvertently bridged.

5-10-3 The protective conductor shall be connected only to the exposed parts of those items of electrical Equipment whose supply will be interrupted in the event of the protective device operating under fault Condition.

5-10-4 Excessive earth –leakage current requirements under consideration.

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5-11

Earthing Arrangement for functional purpose

5-11-1

General Earthing arrangement for functional purpose shall be provided to ensure correct operation of Equipment to permit reliable and proper functioning of installations (Further requirement under consideration)

5-11-2 Low noise

5-12 Earthing arrangement for combined protective and functional purposes 5-12-1 General Where earthing for combined protective and functional purpose is required, the requirements for Protective measures shall prevail.

5-12-2

PEN conductor

5-12-3

In TN system, for cables in fixed installations having a cross-sectional area not less than 10mm In copper or 16mm in aluminum, a single conductor may serve both as protective conductor And neutral conductor, provided that the part of the installation concerned is not protected By residual current-operated device.

However the minimum cross-sectional area of a PEN conductor may be 4mm provided that the cable Is of a concentric type conforming to IEC standard and that duplicated continuity connections exist at all joints and terminations in the runs of the concentric conductor.

Page 65


5-12-4 The PEN conductor shall be insulated for the highest 5 volt to which it may be subjected to avoid story Current. Note: - The PEN conductor need not be insulated inside switchgear and control gear assemblies.

5-12-5

If from any point of the installation the neutral and protective functions are provided by separated Conductors, it is inadmissible to connect these conductors to each other from that point. At the Point of separate terminal or bars shall be provided for the protective and neutral conductor. The PEN conductor shall be connected to the terminal or bar intended for the protective conductor .

5-13

Equipotential bonding conductors

5-13-1

Minimum cross-sectional area

5-13-2

Main equipotential bonding conductors shall have cross-sectional areas not less than half the Cross-sectional area of the largest protective conductor of the installation subject to a minimum Of 6mm .The cross-sectional area need not however, exceed 25 mm if the bonding conductor is of Copper cross-sectional area affording equivalent current –carrying capacity in other metal.

5-13-3

Supplementary equipotential bonding conductor a supplementary equipotential bonding conductor connecting two exposed conductive parts may have a cross-sectional area not less than that of the Smaller protective conductor connected to the exposed conductive parts

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Supplementary equipotential bonding conductor connecting exposed conductive parts to extraneous Conductive parts may have a cross-sectional area not less than half the cross sectional area of the Corresponding protective conductor. Supplementary equipotential binding may be extraneous conductive parts of permanent nature ,such As structural metalwork or by supplementary conductors, or by a combination of these.

5-13-4

Bonding of water meters: - where pipes of building are used for earthing purpose or as protective Conductors the water meter shall be bonded a cross and the bonding conductor shall be of Appropriate cross sectional area according to its use as a protective conductor, equipotential bonding Conductor or functional earthing conductor.

Page 67


Section -6

INSTALLATION DETAILS Types of wiring systems The type of wiring system that may be used shall divided into two categories depending on the building construction. a) Buildings constructed of concrete floors with concrete blocks used for walls partitions etc. b) Prefabricated buildings constructed of timber, asbestos, cement panels etc. with fiber glass or other approved insulation material in the exterior walls and roof space. Wiring installed in the buildings complying with category (a) or above shall be carried out using PVC cable run in galvanized steel conduit or high impact rigid PVC conduit concealed within the building fabric. Any alternation from the original design that may be made after the start of the installation shall be carried out using the same method. Where an installation is to be carried out within a false ceiling space then an alternative wiring system may be used within a the false ceiling space but only after consultation and written approval is obtained from the ministry of Electricity and water regarding the type of installation to be used. Wiring installed in the buildings complying with category (a) or above may be carried out using the same method used for category (a) or may be carried out using PVC insulated and sheathed cables complying with B.S no 6004 or other equivalent. It must be noted that joints are not permitted where flat twin earth pass through slots or holes in metal framing, the cables shall be protected by brushings or grommets securely fastened in the slots or holes. Note: prefabricated buildings using concrete wall panels or similar material may be wired using se4mi-rigid PVC heavy gauge conduit. The jointing of the conduit in the wall to the ceiling or floor slab may be carried out using a length of flexible PVC conduit provided that this length does not exceed 400 mm, however, all materials used for this method construction must be submitted to SEWA for written approval prior to installation. This shall be apply to the conduit, couplings, boxes and brushes.

Page 68


CONDUCTORS:

6-1-1 The conductors or cables to be used in any part of an installation shall be determined by consideration of: a) Current carrying capacity b) Voltage drop c) Temperature conditions (45 C Ambient within a building, 50 c Ambient outside temperature) d) Mechanical strength It is responsibility of the electrical contractor to ensure that suitable materials are used.

6-1-2

Current Carrying Capacity The live or phase conductors of a 3 phase sub main or final sub-circuit shall be of same cross sectional area and have the same insulation grade. The current carrying capacities of cables to be used are to be found in tables 8, appendix 3 of these regulations.

6-1-3

Page 69

Neutral conductor for single and three phase circuits or sub mains shall be of same cross sectional area as the live conductors and of same insulation grade. If a cable supplies an installation of three phase motors only, no neutral conductor is required.


6-1-4

Where a conductor is to be run for a significant length in a space to which thermal insulation is likely to be applied, the cable shall , wherever practicable, be fixed in a position such that it will not covered by the thermal insulation. Where fixing in such a position is impracticable, the current carrying capacity of the cable shall be appropriately reduced.

Note: For a cable installed in a thermally insulation wall or above thermally insulated ceiling, the cable being in contact with a thermally conductive surface on one side, the rating factor to be applied may, in the absence of more precise information, be taken as 0.75 times the current carrying capacity for that cable clipped totally surrounded by thermally insulating material;, the applicable rating factor shall be 0.5

6-1-5

Voltage drop: The fall in voltage from the commencement of the consumer's main to the point on the installation shall not exceed 2.5 % of the declared voltage when all the conductors in the insulation are carrying the maximum current which they have to carry including an assumed future additional loading.

6-2 Selection of types of Wiring Non Flexible cables and conductors for low voltage: 6-2-1 Every non- flexible cable at low voltage shall be selected from one of the following types and shall comply with the appropriate British standard referred to below, so far as this applicable. 6-2-2 In cables every type, conductors shall be of copper.

Maximum Ambient Temperature: 1)

non armored PVC insulated cable 6004 BS 6231 type B, or BS 6346 70c

2)

Steel wire armoured PVC insulated cables, lead sheathed BS 6346 70C

3)

Impregnated- paper insulated cables lead sheathed BS 6480, mass impregnated, non draining

Page 70

75C


4)

Armored cables with thermosetting insulation (BS 5480) (XLPE) 90C

5)

Mineral insulated cables BS 6207, part1 or 2 , with , where appropriate, fitting to BS 6081

6)

With or with out PVC sheath, exposed to touch 75C

7)

Without PVC sheath, not exposed to touch and with 105C termination 100C

8)

Without PVC sheath, not exposed to touch and with 150 termination 145C

9)

Butyl or e.p rubber 80C

10) Silicon rubber

145C

11) Glass fiber

175C

6-2-3 Every flexible cable and flexible cord shall be selected from one of the following types: i.

Circular sheathed (3 Core)

ii.

Flat twin sheathed.

6-2-4 Single core PVC or XLPE insulated, non armored cabled used for wiring of a.c circuits shall be identified by the following colors: a) Cables to final distribution Boards operating at 415v shall be identified by phase colors red, yellow or blue. Neutral shall be black only.

Page 71


b) Cable to final distribution boards operating at 415 V shall be of the actual color of the phase used to supply the distribution board. c) All single phase circuits from final distribution shall be wired in respective phase colors. d) Where three phase circuits with neutral are to be utilized from final distribution boards they shall be wired in re, yellow, blue and black only.

e) Earth- green/ yellow stripped cable, along the cable length. Green insulated cable will not be acceptable for use in wiring installations.

6-2-5

Conductors of multi core PVC or XLPE insulated armored cables shall be identified by the following colors: a. Two core cable: red phase, black neutral (applicable only to armored cable) two core cable unarmored cable will not be accepted. b. Three core Cable: Red, yellow, blue to indicate three phases or red, black, green/yellow for single phase circuits c. Four core cable: red, yellow, blue, black.

6-2-6

All Conductors connected to neutral shall have black insulation and shall not be used as phase conductor. Green/ yellow conductors to be used as earth or bonding only.

6-2-7

For mineral insulated cables or paper insulated cables the application at terminations of sleeves or discs of the appropriate colors noted above shall be used to identify phase's neutral and earth.

Page 72


6-2-8

All flexible cables and cords shall have the following identification. a) two Core: Brown-Phase; Black- neutral b) three core: Brown-Phase; Blue- neutral; Green/yellow earth. c) Four or five core : Black insulation. Each conductor identified by a number or letter in white which shall be part of the insulation and a peering at intervals of not more than 100mm; along the length of the insulation.

6-2-9 Cable cores and flexible shall be identified throughout the entire route length with the appropriate color implemented into the insulation. Changes of core color by use of sheathing or tape at terminations will not be permitted, except as noted 610.6. flexible cables and cords shall not be used as a substitute for fixed wiring nor shall fixed wiring cables be used as a substitute for flexible cords.

6-3 6-4

Connection for Conductors in parallel:

The following conductors shall not be connected in parallel: a) live conductors having a current carrying capacity up to and including 150 Amperes. b) Any earthing conductors. Where the conductors are connected in parallel the express written approval of SEWA shall be obtained in each instance.

Page 73


Sub Mains 6-5-1

Limitation of the Maximum size of a sub- main

The maximum current carrying capacity of anyone sub main installation shall be 600 Amp 3 phase for any commercial or industrial complex and 400 Amp 3 phase for any domestic complex The maximum fault level sub-main board incorporated shall e 25 KA for 3 seconds exception to this rule shall only be granted by the inspecting authority of the SEWA.

6-6

Where sub-main cables are installed below the ground, they shall either be run in a concrete or brick cable trench with removable or in non-metallic pipes of a minimum diameter of 100mm. this shall only apply if finished surface below which the cables are running is anything other than soil or sand. Where the cables are laid below a soil or sand surface then a trench shall made and a layer of dune sand shall be laid to a thickness of 200 mm before the trench is back filled. Cable marking tape shall be installed over the top layer of sand throughout the cable route. Cable tiles are not required for medium voltage cables.

6-7

Installation of sub main cables (above ground)

6-7-1

All conductors and cables shall be adequately protected by against any risk of mechanical damage to which they may be reliable in normal conditions of service.

6-7-2

Where cables pass through holes in metal work, precautions shall be taken to prevent abrasion of the cable on any sharp edges.

6-7-3

Non sheathed cables shall be protected by enclosure in conduit, duct or trunking throughout their entire length.

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6-7-4

Cables shall be run in a lift (or hoist) shaft unless they form a part of the lift installation. Cables for lift installation, other than traveling cables, in such a shaft shall be a) Armored, or PVC insulated in galvanized steel conduit. b) MICC /PVC sheathed c) See also regulation/ for electric passenger and goods lifts.

6-7-5

The internal radius of every bend in a cable shall be not less than the appropriate value stated in appendix.

6-7-6

Every cable installed in or on a building shall be supported by one of the methods described below, and shall be so arranged that there is no appreciable mechanical strain on any cable termination.

Page 75

i)

For non- sheathed cable, installation in conduit, without further fixing of the cables, provided that precautions are taken against undue compression of the insulation at the top of any vertical runs exceeding 4m in length.

ii)

For non sheathed cables, installation in trunking, without further fixing of the cables, provided that vertical runs shall not exceed 4m in length without immediate support of cables within the trunking.

iii)

For sheathed and/ or armoured cable installed in inaccessible and accessible position, support by clips or saddles at spacing not exceeding the appropriate value stated in table no 5

iv)

For cables of any type, resting without fixing in horizontal runs in ducts or trunking (this shall not apply to cable tray or ladder).


v)

For rubber or PVC sheathed cable, installation in conduit, without further fixing of the cables, provided that any vertical runs shall be in conduit of suitable size and shall not exceed 4 m in length.

Note: cable ties manufactured of PVC, nylon or other similar material shall not be used to support multi core on cable, trays fitted vertically

6-7-7

Every cable shall be so selected and installed as to be suitable for operation under such ambient temperatures of its surroundings as are likely to occur. Which shall not exceed the appropriate value stated in section 610-1.

6-7-8

Termination of mineral insulated cables shall be provided with sleeves having a temperature rating not less than that of the seals.

6-7-9

Cables for AC circuits- Electromagnetic effects single core cables armoured with steel wire or tape shall not be used for AC circuits installed in ferrous enclosures shall be arranged so that the conductors of all phases and the neutral conductors are contained on the same enclosure. Where such conductors enter ferrous enclosures they shall be arranged so that the conductors are not separate any ferrous material, or provisions shall be made to prevent circulating eddy currents.

6-7-10 Where cables, conduits rising main busbars, ducts or trunking pass through floors walls, partitions or ceilings, the surrounding hole shall be made good with cement or similar fire resisting material to the full thickness of the floor, wall etc. and space through fire or smoke might spread shall be left around the cable, conduit, duct or trunking. In addition, where cables conduits or conductors are installed in channels, ducts, rising main bus bar trunking or shafts which pass through floors, walls, partitions or ceiling, suitable internal fire-resisting barriers shall be provided to prevent the spread of fire.

6-7-11 Every connection at a cable termination shall be made by means of a terminal soldering socket, shall securely contain and anchor all the wires of the conductor and shall not impose any appreciable mechanical strain on the terminal or socket.

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6-7-12 In any situation, the exposed conductor and insulation of cables insulated with impregnated shall be protected from ingress of moisture by being suitable sealed.

6-7-13 The ends of mineral- insulated metal sheathed cables shall be protected from moisture by being suitably sealed and the insulation shall be thoroughly dry before the sealing material is applied. Such sealing material, and any material used to insulate the conductors where they emerge form the insulation, shall retain these properties throughout the range of temperatures to which the cable is subject in service.

6-7-14 Cable glands shall securely retain the outer sheath or armour of the cables without damage to these and , where necessary, shall incorporate adequate means of maintaining earth continuity between the sheath or armour and the threaded fixing component or the gland. Cable glands shall not be buried within the building fabric.

6-7-15 Any cable, armoured or unarmoured, installed on the surface of the binding fabric and exposed to the ambient conditions shall be protected from direct sunlight.

6-8

Buried extra low voltage cabling should be installed with some degree of protection against aggressive soil conditions and stones. PVC/SWA cables will be accepted buried in sand. Cables without armour must be installed in rigid PVC conductor conduits, or alkathene piping of strength sufficient to resist a glancing below by a spade. Hose piping or piping made of very soft flexible material will not be acceptable.

6-9

Page 77

Joints in cables cable jointing is not allowed and should not be used any where in the installation unless special approval obtained from SEWA.


6-10

Busways And Busbar Risers

6-10-1 This rule shall be apply to bus way for the purpose of current distribution of mains, or sub mains where cables are found impractical to use as a result of voltage drop limitations or general physical size due to large electrical; loads. This rule does not apply to busbars used for switchboard wiring.

6-10-2

Circuit protection The conductors of a busway shall be protected by HRC fuses- or by a suitable circuit breaker which will open the circuit under fault conditions.

6-10-3

Limitation on use : Busways shall not be connected to circuits in which the voltage exceeds medium voltage. They shall be installed only in positions such that they are accessible for inspection and repair throughout their entire legth. Each rising main busbar trunking installed, shall supply a maximum of 6 floors without exception unless otherwise approved by SEWA. Busbar risers shall not be installed i)

where they would be subject to mechanical injury.

ii)

Where they would be exposed to liquid or corrosive fumes.

iii)

In an atmosphere in which flammable or explosive gases or dust may be present (unless the busway is of an approved type).

iv)

In any damp situation or out of doors, unless specially approved for the purpose by the SEWA.

Any switch, fuse or circuit breaker mounted on busways shall be separated from the space within the busway by substantial barriers of non-ignitable material.

Page 78


The main maximum distance of cable tail interconnections from the busway and any tap off unit shall be 750 mm.

6-10-4 Support of Busway The enclosures of busway shall be securely supported at intervals not exceeding 1.8 meters.

6-10-5 Expansion of busbars Where necessary , provision shall be made for thermal expansion.

6-10-6

Outer enclosure as Earthing medium The outer enclosure shall not be used as an earth path in any circumstances. A separate earth continuity conductor shall be run along with the busway adjacent to it and the case of the busway bonded to the earth cable at both the start and finish of the length of the run. The earth continuity conductor will be copper bar with half the size of that for phases.

6-10-7 Passage through wall and floor. The following things are to be taken care while busbar is passing through wall or floor

Page 79

i)

The wall or floor is dry.

ii)

The busway is in unbroken length where it passes through the wall or floor.

iii)

The busway is provided with an internal barrier of non ignitable insulating material to prevent the spread of fire where the busway passes through the wall or floor.


iv)

6-10-8

Where the busway passes through the floor slab, the floor surrounding the busway shall be raised by a minimum of 100 mm to prevent any water draining into the floor penetration the raised floor area or nib shall be constructed of concrete.

Any sub mains, or final circuits, supplied from a busway shall be protected against over current by either HRC fuses or a circuit breaker.

6-10-9 Busways use is compulsory for high rise buildings consisting of more than 15 floors. 6-10-10 6-11

Busways to be protected to a degree of IP67.

Cable trays

6-11-1 Cable trays may be employed in ware house and other industrial buildings, for supporting cables. In residential and commercial buildings cable may be employed in mechanical equipment and plant rooms. Where service floors or similar facilities are available cable trays may be employed at other locations in commercial and residential buildings also.

6-11-2 A Cable tray system shall comprise a unit or assembly of units or sections and associate fittings, made of metal or non combustible material, forming a rigid structural system. Cable tray system include ladders, through, channels and solid bottom trays.

6-11-3 Multi core armored or non armoured cables may be supported by cable trays. Single core insulated and shaeathed cables may also be installed in cable trays.

6-11-4 Cable trays shall not be used in locations where they will be subjected to severe physical damage.

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6-11-5 Cable trays shall have adequate strength and rigidity to provide satisfactory support for the cables contained within them. All sharp edges, burrs and projections shall be removed and the tray shall be finished smooth to prevent injury to cable.

6-11-6 Metallic cable trays shall be adequate protected against corrosion by galvanizing ao shall made of corrosion resistant material.

6-11-7 Non –metallic cable trays shall be made from polyvinyl chloride or equivalent and shall be fully suitable for continues service in the local climate conditions.

6-11-8 All cable trays shall be equipped with sides of adequate dimensions. All fittings bends, tees, employed shall be substantial sections and of the same quality as the tray itself.

6-11-9 Cable trays shall be installed as complete system with bents and other accessories. Each run of cables tray shall be completed before the installation of cables.

6-11-10

Adequate supports shall be provided to prevent stress on cables where they enter or leave the tray. Where cable tray extends transversely through partitions and walls additional protection in the form of non- combustible covers shall be used.

6-11-11

Sufficient space shall be provided and maintained around cable trays to permit adequate access for installing and maintaining the cables.

6-11-12

The number of multi core cables that may be installed in a ventilated or solid bottom cable tray shall be greater than the number given in the table 2a.

6-11-13

Metallic cable tray shall not be used as an earth continuity conductor, although sections shall be bonded using copper links.

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6-12

Cable Trunking System:

6-12-1 Cable trunking may be employed for housing single core cables at special location where it is difficult to install conduits. They may be of metallic or non metallic construction. Non metallic cable trunking shall be constructed from non –combustible insulation material such as polyvinyl chloride which shall be fully suitable for use in the climate conditions. Metallic cable trunking shall be adequately protected against corrosion by galvanizing or shall be made of corrosion resistant material. All cable trunking shall be provided with removable covers.

6-12-2

Cable trunking shall, generally, be run exposed and the trunking shall be completely erected before drawing in the cables. Where adequate means of access is readily available throughout its entire lenth, cable trunking may be concealed.

6-12-3 Every entry to trunking shall be so placed as to prevent the ingress of water and all dead ends shall be closed. Only unbroken lengths of trunking shall be employed for crossing partitions and walls.

6-12-4 Where common cable trunkng is employed for housing, both power and communication circuits, or for housing circuits operating at different voltages, the trunking shall be provided with separate compartments for the different types of circuits. See 660-1

6-12-5 Cable trunking shall be manufactured from substantial sections to provide adequate strength and rigidity. All sharp edges, burrs and other projections shall be removed and the trunking finished smooth to prevent injury to cables.

6-12-6 All bents. Tees and other accessories of cable trunking shall be of substantial sections and of the same quality as the trunking itself.

6-12-7 Cable trunking shall be securely supported every meter, when run exposed.

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6-12-8 The number of single core cables that may be housed in a trunking shall be selected in accordance with the method detailed in table 2 and 3.

Note: Where a number of cables are bunched in a trunking the current carrying capacity of the cables shall be reduced by using the stipulated grouping factor.

6-12-9 The different sections of a trunking shall be boned by copper links although the trunking shall not be used as the primary earth conductor.

6-12-10 Under Floor Trunking Systems Under floor trunking system may be used for the distribution of general power installation, telephones and other communication systems throughout a building. However the use of floor mounted 13 A socket whether recessed in to the floor outlet box or mounted on a pedestal will not be permitted in any circumstances unless the floor is to be carpeted. Other floor finishes cannot be used in conjunction with floor mounted socket outlets.

6-13

Conduits

6-13-1 Types of conduits Only galvanized steel or rigid, high impact, heavy gauge PVC conduit Shall be used for any installation where conduit5 is to be installed. Conduits of any kind shall be used for wiring within substation only. M.I.C.C/PVC sheathed cables shall be used in these locations. PVC and galvanized conduit shall not be mixed on any length of run without the prior approval of SEWA.

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6-14-1 Rigid Metallic Conduit; The metallic conduit and its accessories shall form a continues metallic sheath of adequate strength surrounding the cables through the length of the conduit.

6-14-2 Metallic conduit shall not be run under the floor tiles of the buildings. 6-14-3 The bores of all conduits shall be smooth and free from projections and sharp edges which may injure the wires or prevent them from being drawn. The internal edges of the ends of all lengths of conduit shall be raised or chamfered before assembling in to position.

6-14-4 All runs conduit shall be assembled complete with all necessary accessories and the whole firmly attached to the structure of the building before any wires are any wires are drawn in. All wires shall be drawn through the covers of inspection and other fittings installed for the purpose.

6-14-5 All thread, vice marks tool marks and breaks in the protective coating on metallic conduit and /or conduit fittings shall be painted with a steel preserving paint immediately after erection.

6-14-6 No run of conduit shall exceed 10 meters between adjacent draw in points nor does certain more than two right angle bend sets or other deviation from the straight line.

6-14-7 Inspection coupling or draw-in boxes shall be used where necessary in straight runs or conduits for draw in purposes and shall be placed so that cables can be inspected and if necessary, withdrawn throughout the life of installation.

6-14-8 Where conduit and/or conduit fittings are attached to switches distribution boards, boxes or other equipment, smooth bore male brass brushes and flanged couples shall be used.

Page 84


6-14-9 Circular or hexagonal heavy locknuts shall be used at all positions where running joints are required and care shall be taken to see that seat firmly and evenly into mating faces of couplings or couplings or other accessories.

6-14-10

Where exposed to water, rain or whether, all covers shall be arranged or fitted with machined joints and /or fitted with durable gaskets such as water cannot penetrate.

6-14-11

Except where provision is made for fastening, conduits shall be saddled to the structure of the building within 15 cms of each terminal box, angle boxes bend or other conduit fittings at the intervals not less than 1.5 m, coupling and through type drawing boxes shall be counted as a part of a straight run of conduit.

6-14-12

All boxes, bends and other accessories shall be of the same manner as the conduit and shall have the same protective coatings. Grey cast iron box etc. may be used with metallic conduit, but shall be finished in the same manner as the conduit to which they are directly attached.

6-14-13

The number of single core PVC insulated non sheathed cables run in metallic conduit shall such as to permit easy drawing of the cables. The actual number of cables drawn into any conduit shall not be greater than the number given in the Table 4.

6-14-14

The minimum size of metallic conduit that may be used in electrical installations shall be 20 mm diameter. Other sizes of conduits shall be limited to the following diameters, 25 mm, 32mm, and 50 mm.

6-14-15

Galvanized conduit boxes used for all electrical accessories including light switches and socket outlet etc, shall be fitted brass earth terminal.

Page 85


6-15

Rigid Non-metallic Conduits

6-15-1

Rigid non-metallic conduit may be employed in general electrical installations provided it is made from polyvinyl chloride or equivalent material that have been certified as suitable for use at ambient temperatures up to 55 C, shall be non hygroscopic and self extinguishing type. Rigid PVC conduit shall not be in the following locations: a) Where exposed to the outside ambient temperature b) Where it may be affected by the chemicals to cause deterioration in its construction. c) Any part of a hospital for lighting and power circuits. d) Petrol stations and forecourts. e) The same room as a diesel generator f) Plant room, lift motor rooms and lift shafts g) Substations

6-15-2 The inside and outside surfaces or non- metallic conduits shall be smooth and free from burrs and similar defects. The interior and ends of conduit fittings shall have no sharp edges and corners, shall be smooth and well rounded to permit easy drawing in of cable and prevent any damages to cable insulation.

6-15-3 The entries of a non-metallic conduit shall be so designed that a reliable water tight joint can be made between the conduit and fittings. Vinyl cement shall be used to make all joints- A vinyl solvent shall be used for permanent joints and cement shall be used for expansion couples.

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6-15-4 The minimum size of rigid nonmetallic conduit used for general electrical installation shall be 20 mm diameter. Other sizes of rigid non metallic conduits shall be of the following diameters, 25 mm, 32 mm, 38 mm, and 50 mm.

6-15-5 The number of single core PVC insulated non sheathed cables run in one conduit shall be such that it permits easy drawing of the cables. The actual number of cables drawn into any conduits shall not be greater than the number given in the table 4.

6-15-6 A separate insulated earth wire shall be drawn into all rigid non metallic conduits for each circuit, the cables of which pass through the conduits.

6-15-7 Rigid non metallic conduits shall be installed generally in accordance the requirements set out for metallic conduits shall allow for the longitudinal expansion and contraction of the conduits.

6-15-8 Where a light fitting is suspended from a non-metallic conduit box, care shall be taken to ensure that the temperature of the box does not exceed the permitted safe temperature of the material and is fixed with screwed metal insert clips. The mass suspended from the box shall not exceed 2 KGs.

6-15-9 Electrical conduits, where required to be distinguished from pipe lines of other services. Shall use orange as the basic identification colors.

6-15-10 PVC conduit boxes for all electrical accessories including light switches and socket outlet etc. Shall have a fitted brass fixing sockets tapped for 3.5 metric thread.

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6-15

Flexible Conduits

6-16-1 Flexible conduits may be employed for connecting electrical motors and other equipment subject to adjustment of position and vibration to the fixed wiring.

6-16-2 Flexible conduits may be of the metallic type only. Metallic flexible conduits shall may not be used as the sole means of providing earth continuity and separate earth continuity conductor of appropriate size shall be provided.

6-16-3 In damp and wet locations all flexible conduits shall be of the type that prevents the ingress of water and moisture. 6-16-4 Flexible conduit shall only be run exposed and shall be so positioned that they are susceptible to mechanical damage, Where necessary flexible conduit shall be adequately supported.

6-16-5 The ends of flexible conduit shall be securely anchored to the fixed conduit or equipment to which it is attached by approved flexible conduit adaptors that maintain effective mechanical continuity securely in position without restoring it. The flexible conduit shall not be used as part of the earth conductor. A separate earth conductor shall be installed to comply with the same requirements for rigid conduit installations.

6-16-6 The maximum length of a flexible conduit run shall be 2.5 meters. Where flexible conduit is installed less than 1.5 meters above a floor in a position where it may be easily distributed or reached, it shall be supported at intervals not exceeding 300 mm except where terminating at motors or at other equipment which requires a free length of flexible conduit to provide for normal movement.

6-17

Segregation of circuits:

6-17-1 Where an installation comprises extra low voltage or telecommunication or fire alarm circuits as well as circuits operating at low or medium voltage, precautions shall be taken in accordance with the following to prevent both electrical and physical contact between the cables of various types of circuit. See 635-4

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These types of circuits shall be divided into the following categories • • • •

Category 1 Circuit: a Circuit (other than a fire alarm or emergency lighting Circuit) operating at LV and supplied from the Mains supply system. Category 2 Circuit: All low and extra low voltage circuits Category 3 Circuit: a fire alarm or emergency lighting Circuit. Category 4 Circuit: All telecommunication circuits which are not supplied from mains supply system

6-17-2 Cable of Category No 1 circuits shall not be drawn in to the same conduit, pipe, trunking, duct, or run on the same cable tray, as cable category No 2 unless the letter cables are insulated to the same degree for the highest voltage present in the category No 1 circuits.

6-17-3 Cable of Category No 1 circuits shall not in any circumstances be drawn in to the same circuit trunking or duct as cables of category No3 circuits.

6-17-4 Cable of Category No 1 circuits shall not in any circumstances be drawn in to the same circuit trunking or duct as cables of category No4 circuits.

6-17-5 Cable of Category No 4 circuits relating to their own specific system shall be installed remotely from the another in their same conduit, pipe, trunking or duct.

6-17-6 Cable of Category 2,3 and 4 shall not in any circumstances be drawn in to the same circuit trunking or duct as cables of category No1 circuits.

6-17-7 Where a common channel or trunking is used to contain cables of the three categories shall be separated by means of continues partitions of fire resisting material.

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6-17-8 Cable of Category 1 and 2 shall not in any circumstances be contained in a common multi core cable, flexible cable or flexible cord.

6-18

Multi Storied Buildings:

6-18-1 This section shall apply to high rose buildings where there are three or more floors. A three phase neutral and earth rising main system shall be installed in a common riser duct with tap- off units and SMDBs at each floor level.

6-18-2 The rising main may be either of the busbar (busway) or multi core cable XLPE/SWA/PVC cable or MICC/PVC type. See also section 625.

6-18-3 The SMDB will be fed directly from the tap off units or will be connected directly to the main riser cables. 6-18-4 The consumer's premises will be fed directly through individual MCCB (outgoings of the SMDB) through the SEWA energy meters.

6-18-5 Meters will be arranged on fireproof plywood covered with asbestos as shown on the appendix. Conduit will be run to the distribution board located within each consumer premises.

6-18-6 Single core , or armoured cable may be used to supply the premises including proper trunking to be used for proper cable glanding

6-18-7 The maximum load on each SMDB shall be not exceed 200KW ie,400A in case of more load in one floor two SMDBs can be used.

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6-18-8 The maximum number of floors to be connected to busway should not exceed 12 unless otherwise approved by SEWA.

6-18-9 The maximum number of premises can be connected to SMDB shall not be exceeding 16. 6-18-10 Single phase supply to be used for premises where the total connected load not exceeding 7 KW, and a minimum of 40A MCCB should be used for each flat or premises.

6-18-11 When assessing loading of the building a diversity of 0.8 may be allowed except for AC equipments there will be no diversity.

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Section -7

FINAL SUB CIRCUITS

7-1

Lighting:

7-1-1 All lighting circuit shall be installed with a minimum loading of 1800 Watts per circuits. The following table be sets out the cable size and circuit breaker relationship for the maximum permissible electrical load to be connected to the circuit. The only circuit breaker sizes permitted to be used are 5, 10 and 15 Amp. The maximum electrical loading applies to tungsten lighting and discharge lighting including all control gear losses, for installation with direct switched circuits.

Circuit Breaker capacity Main conductor Size

Earth conductor size

Max loading of Circuits

mm2

mm2

(watts)

6

1.5

1.5

600

10

2.5

2.5

1200

16

4

4

1800

(AMPS)

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When contractor control is used for lighting circuits, loading may be increased to 7 KW per circuit. Heat resisting flexible cords of minimum size 10 mm2, this included cords insulated with butyl rubber, silicon rubber or glass fiber, must be used for connection between the ceiling rose and lamp holders for pendent type light fittings. When battern lamp holders or enclosed lighting are used, the final connection shall be made by heating cables, or cable cores shall be individually protected by sleeves of suitable heat resisting material e.g silicon bonded glass braiding.

7-1-2 Mains operated clock points may be connected to nearest lighting circuits provided an approved fuse clock outlet point is installed adjacent to or behind the clock for connection there to suspended false ceiling installations.

7-2-1 Light fittings ( both tungsten and florescent) shall be supported by one of the following methods. a) Direct support from false ceiling frame work (providing the ceiling has been designed to withstand the weight of the light fittings). When using this method it shall be possible to completely withdraw the light fitting from the ceiling without damage to the ceiling or reducing its rigidity. b) Metal conduit support from the underside of the structural slab. A fluorescent fitting shall have a minimum of two conduit support. Each conduit shall terminate at the fitting by means of a screwed couple and male brass bush to give leveling adjustments of the fitting. c) Metal treaded rod support from the underside of the structural slab. A fluorescent fitting shall have a minimum of two rods for surface or flush mounting provided when flush mounted, adequate support shall be given. Each rod shall be secured into the structural ceiling by means of rowel bolt or other approved means and at the light fitting, by means of nuts and washers to give the leveling adjustments required.

Page 93


d) Chain support from the underside of structural slab. A florescent fitting shall have minimum of two chains for surface or flush mounting provided, when flush mounted, adequate support shall be given. Each chain shll be secured to the structural slab by means of a hook, and at the light fitting, by an approved hook with threaded portion to allow for the leveling of the light fitting. Note:

In no circumstances will supports be permitted to be installed for securing any light fitting.

7-2-2

Wiring to the light fitting shall be run within the conduit system where the loop-in principle is used, as detailed in 702-1 (a) or shall be by means of ceiling in 702-1 (b),(c) (d). Where the flexible cable passes through the body of the light fitting a suitable rubber grommet shall be provided.

7-3 Direct to sophist of structural slab 7-3-1

Light fittings shall be secured direct to the conduit box. Where enclosed tungsten light fittings are fixed directly to a PVC high impact circular box, steel insert clips must be used for fitting the light fitting to the box. The method of using the normal fixing inserts is not approved due to the heat transfer from fitting inserts is not approver due to the heat transfer from the fitting to the PVC box. Two conduit box fixing shall be required on florescent fitting greater than 600 mm in length. Note: Whichever method of suspension is adopted it should be ensured that the light fitting is adequately ventilated and where appropriate, suitable spacers must be installed to ensure a minimum gap of 6 mm exist between fitting and the finished ceiling.

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7-4

Power Factor Correction

7-5

A florescent light fitting shall have a minimum power factor of 0.85 lagging Lighting track system to BS 4533 are considered to be one point provided that the individual luminaries have protecting fuses.

7-6

All outside points shall be installed on their own separate circuit or circuits. Light fitting and switches not installed inside the building shall be whether proof with suitable sealing gaskets.

7-7

Under water lighting.

7-7-1 7-7-2

All circuits feeding under water lights shall be designed and installed to ensure full safety for personnel.

All circuits feeding underwater lighting circuits shall operate at a voltage not exceeding 36 Volts. Exemption: in large, decorative foundations, where adequate fencing and guarding is provided to ensure that only competent persons can come in contact with the pool the normal system voltage may be employed

7-7-3

Lighting fixtures and all other equipment employed in the pool shall be of approved manufacturers and/tested to ensure complete safety in operation.

7-7-4

All circuit feeding pool light shall be protected by a current operated earth leakage circuit breaker associated with the under water light, viz. pumps, etc, shall be protected by a current operating circuit breaker having a trip rating of 30 milliamps.

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7-7-5

All electrical equipments, light fitting, transformers and accessories shall be connected securely to the earthing system.

7-7-6

All metallic parts of the pool structure, including the reinforcing steel, all metal fitting within or attached to the pool structure and all metal parts of electrical equipment shall be bonded together.

7-7-7

Installations of over 10 KW load shall be subjected to individual written approval of SEWA.

General 7-8

13 Amp switched socket outlets installed in rooms other than kitchens, shall be connected using the ring main principle with a maximum num of 8 socket outlets on anyone circuit, or one circuit not covering a floor area of greater than 10 m2

7-8-1

Each ring main shall be connected to its own circuit on the distribution board using 4.00 m2 PVC cable for the earth conductor and shall be protected by 30 Amp MCB. All conductors shall complete the ring of each circuits, including the earth conductor.

7-8-2

No socket outlets shall be permitted in bathrooms, shower room, or toilets in any circumstances.

All light switches controlling the lighting within bathrooms, shower room or toilets shall be located outside the room unless ceiling mounted pull cord operated switches are used when they may be located immediately inside the access door. Shaver socket outlets may be installed in bathrooms, provided to comply with BS3052.

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Pendant type light fittings shall not be permitted in bathrooms. It is recommended to install a bathroom circuit from he second section of DB. (see450-11). That is the type of electrical fittings for the water proof facility may be disregarded on the condition to install a protective cover to ensure no water is splashes into the internal elements when using the bathroom. Failure to install the earth leakage circuit breaker in bathrooms, the SEWA enforces for all light fitting shall be weather proof to IP 33

7-8-3

Extract fan shall be controlled from a separate switch of the same type as the light switch and shall be situated adjacent to it.

7-8-4

One socket outlet of 13 A rating may be connected to a single phase and neutral circuit wired with 3x4mm2, sc cables, protected by a fuse or circuit breaker not exceeding 16 A.

7-8-5

One special purpose outlet of 15 or 16 Amps rating may be connected to all single phase and neutral circuit wired within 4mm2 cable, protected by a fuse or circuit breaker not exceeding 16 Amps.

7-8-6

No socket outlet shall be mounted within two meters of any tap, sink or basin in any kitchen, cloakroom etc. without the special approval of SEWA in each case. Socket outlets shall be mounted at locations where they are liable to come into physical contact with fabric or other material that may catch fire due to transmission of heat.

7-8-7

Socket outlets rendered inaccessible appliances fastened in place or of a size to be not easily movable will not be permitted.

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7-8-8

7-8-9

No spur outlets will be permitted from any ring main wired in place phase conductor and 4 mm2 earth conductor.

Joints will not be permitted any final circuit wiring except at socket outlets, Switches, ceiling rose, general accessories and light fittings. Screw on thimble type connectors or strait two cables together will not be permitted. This applies to all phase, neutral and earth conductors, connectors blocks or terminal will not be permitted within these boxes.

7-8-10

Each fan coil unit in a central air conditioning system shall be connected to its own 13 Amps switch fused spur unit mounted adjacent to the unit.

7-8-11

Each individual room air conditioning unit up to 2.5 KW of rating shall be connected to an adjacent 20 Amp double pole switch with a separately mounted 30 Amp rated flex outlet( as installed for the low level outlet for a cooker). These two accessories shall be mounted adjacent to each other in separate boxes or in combined box. Each 20 amp double switch shall be on a separate circuit from the distribution board using 4.0 mm2 cable for live and neutral conductors and 4.0 mm2 PVC cable for the earth conductor and shall be protected by a 20 Amp MCB.

7-8-12

Each individual room air conditioning unit above 2.5 KW or rating shall be connected to a 30 Amp double pole switch, with a separately mounted 45 Amp rated flex outlet( as installed for the low level outlet for a cooker). These two accessories shall be mounted adjacent to each other in separate boxes. Were the air conditioner is located out of normal reach, the 45 Amp flex outlet shall be mounted adjacent to the air conditioner but the switch shall be located at normal height.

7-8-13

A split air conditioning unit with both sections adjacent ( on opposite side of the wall or in the roof, it is required for whether proof isolating device to be placed adjacent to the compressor. Each 30 Amp double pole switch shall be on a separate circuit from the distribution board using 6.0 mm2 cable for earth conductor and shall be protected by a 30 Amp MCB.

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7-8-14 Where water pumps are installed on the basis per flat or villa, the means of control shall be from a separate switch, of suitable rating for the pump in question and shall be connected as follows. A)

All single phase water pump motors with a rating of up to 0.37 KW shall be controlled from a 13 Amp switched fuse spur with pilot light, fitted with a 5 Amp fuse and connected into a ring main circuit or a 20 Amp switch with a pilot light on its own separate 20 A circuit fro the distribution board.

B)

All single phase water pump motor with a rating of more than 0.37 KW and all three phase motors shall, be on their own separate circuit and provided with control apparatus incorporating a suitable device affording protection against excess current in the motor or in the cables between the device and the motor. Each motor starter for all three phase motor shall incorporate a phase failure devise which will automatically disconnect the supply from the motor. This device must be manually reset.

SEWA must be consulted regarding starting arrangements for the motors rated above 0.37 KW. All water pump motors, installed remotely from the controlling device, shall be provided with an additional means of isolation immediately adjacent to the motor. Water pumps for any installation shall be located at a minimum distance of 2 Meters from Any tank. Where the controlling device and or the means of isolation is installed outside the building, it shall be of weather proof design.

7-8-15

All items of electrical equipment installed outside the building exposed to the weather conditions, or in a damp area shall be of weather proof type or be enclosed in a whether proof enclosure of degree IP 54 minimum.

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Section -8

POWER FACTOR CORRECTION EQUIPMENT/ CAPACITOR BANK General 8-1-1

This section covers the general requirement of design, manufacture, testing and supply of power factor correction equipment/ capacitor bank.

8-1-2

The contractor shall install the Automatic Power Factor correction Equipment / Capacitor Bank as shown and in full compliance to this specification, the international standards & the SEWA regulations. In case of difference between international standards and SEWA regulations, the more stringent requirements in compliance with SEWA regulations shall prevail.

8-2

Manufacturer & Panel builder/ Assembler

8-2-1

Capacitor bank shall be assembled only by a franchisee of the original manufacturer and approved by SEWA.

8-2-2

Panel Builder/ assembler shall have a minimum experience of 15 years in the field of switchgear assembly and 10 years of experience and authorized by SEWA.

8-2-3

The authorized panel builder / assembler shall design, assemble and test the capacitor bank as per the pre defined guidelines of SEWA. Upon request, the assembler shall obtain approval for the design drawings in writing from SEWA. The original manufacturer and franchised panel builder/ assembler shall have a quality management system conforming to ISO-9001 and shall be certified by an approved certification body.

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8-2-4

The franchised panel builder shall have all the facilities locally & in- house and shall be fully competent staff to design, assemble and test, put in operation and perform the after sale service required for the capacitor banks.

8-2-5

Prior to procurement, the contractor/ panel builder shall submit to SEWA, a detailed technical submittal and shall obtain specific approvals for the capacitor banks. The technical submittal shall include but not limited to the following:

Page 101

•

Company profile and quality management system.

•

Executed project list with details of client, consultant, and project & order value.

•

Franchised agreement from the original manufacturer.

•

Compliance statement to the SEWA regulation and specification.

•

Front side and plan view of the capacitor bank with dimensions.

•

Fixing details/ foundation plan with dimensions.

•

Detailed component arrangement of the capacitor bank

•

Detailed specification of the proposed capacitor bank.

•

Single line diagram.

•

Power & control schematics.

•

Component list including the model no, type ratings, quality and origin.

•

Catalogue copy of each component.

•

One set of original catalogue.( if requested).


8-3

•

Routine test and functional test formats.

•

Test certificate specimen.

Applicable standards

8-3-1

in addition to SEWA regulations unless specified otherwise capacitor bank shall conform to design, material, construction and performance to the latest editions of the international recommendations (IEC standards) and its corresponding British/ European standards (BSEN standards) and in particular to the following publication. Low voltage switch board

IEC 60439

Degree of protection LV circuit breaker & Switch disconnector

IEC 60529 IEC 60947-1 to 5

Power factor correction capacitors

IEC60831-1 & 2

Power factor regulator Capacitor switching contractors

IEC 60664& IEC 1010-1 IEC 60070 & IEC 60831

Detuned reactors

IEC 60289 & IEC 60076

8-4 Site conditions 8-4-1 For general climate conditions, refer and comply the specified UAE climatic conditions. The capacitor bank shall comply and perform satisfactorily at the below listed special design conditions as minimum.

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8-5

Design considerations

8-5-1

The automatic power factor correction equipment/ capacitor banks shall be standard, natural air cooled, well tested and proven design which ensures maximum safety to personnel, maximum service reliability and economic operations for a life time of atleast 20 years. Design and construction shall be simple and well laid out and shall provide good accessibility to component and parts.

8-5-2

Capacitor bank shall be rated on the basis of voltage, current and frequency capacitance, harmonic generating devices and maximum demand inductive load at the installation. The capacitor banks shall be designed for automatic compensations to maintain the power factor of the installation between 0.93 lagging and unity. The following guidelines shall be applied while selecting the type of capacitor for the limiting harmonics associated with the capacitor bank. • • •

8-5-3 8-5-4

Gh< Ssc/120: Standard capacitors as per voltage ratings. Ssc/120Ssc/70: Capacitors voltage rating shall be increased by 10 % and suitably rated harmonic- suppression reactors. ( where Gh is the sum of the KVA ratings of all harmonic generating devices (static converters, invertors, speed controllers etc.) connected to the busbar from which the capacitor bank is supplied & Ssc is the 3 Phase short circuit level in KVA at the terminals of the capacitor bank.)

The electrical system for all capacitor bank shall be 415/380 V, 50hz 3 Phase and neutral, 4 wire solidly earthed.

Unless specified otherwise, the fault level withstand capacity of the capacitor bank shall same as the rating of the respective main distribution board. The breaking capacity of the switching device shall be 25 KA as minimum standard. Even under extreme conditions of major short circuit or mal-operations there shall be no danger for the person in vicinity of the assembly.

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8-5-5

All equipments and components of the capacitor and shall be capable of continues operation at heir full current and voltage rating and detriment or malfunctioning of the system continues deviation of upto and including the following percentage of the normal values • •

Voltage Frequency

+- 10 % +- 5%

All Components shall be capable of withstanding the dynamic, thermal and dielectric stresses resulting from prospective short circuit currents without damage or injury to personnel. Due to the presence of harmonic currents and to manufacturing tolerances, components (MCCB/ isolator, fuses, busbar & power cales) shall be oversized, and based on 1.5 times nominal current.

8-5-6

The capacitorsare automatically switched in steps and the peak value of transient in-rush current from the previously charged units in to the uncharged capacitor group at the instant of switching it into service must not exceed 100 times the rated current of the capacitors in one step of a multi step bank. Small series inductors may be used to achieve this limitation. The instantaneous elements of the protection devices shall be chosen suitably to avoid undesirable nuisance tripping.

8-5-7

A typical capacitor bank shall be consist of, but not limited to the following: •

A suitably sized enclosure with ventilation fan and air inlet filter unit;

•

Triple pole circuit breaker or on- load isolator.

•

Suitable rated GL type fuses, switching contactor and capacitor for each switching step;

•

Series reactors ( where applicable and/or specified)

•

Multi switching step automatic power factor regulator;

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•

Voltmeter with selector switch for mains supply;

•

RYB phase indication lamps;

•

Busbars;

8-6 Constructional Requirements 8-6-1 General 8-6-2

Enclosure construction

8-6-2-1

Capacitor bank enclosure shall be original from approved manufacturer. Wherever the capacitor is the part of main distribution board and inter connected internally with the bus bars, the enclosure be of the same construction as the approved main distribution board.

8-6-2-2

Stand alone capacitor panels shall be cubicle design and robust construction. Enclosure shall be fabricated of minimum 1.5 mm thick electro galvanized sheet steel folded and welded construction. Hinged doors with concealed type of hinges shall be provided at the front. Removable gland plates shall be available at the bottom or top of the enclosure, as per cable entry. Enclosure shall be provided with suitable mounting plates to accommodate all the components. Wherever applicable, cubicles those are similar in construction, height and depth may be joined together to assemble the higher rated capacitor banks.

8-6-2-3

Rear access type panels shall have a hinged door at the front, door or cover at the rear for access. The front door shall have a standard handles with an optional feature of having a key lock, whenever required.

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8-6-2-4

The complete enclosure assembly shall be coated with durable scratch resistant texture paint finish, epoxy powder polymerized at high temperatures to an approved color.

8-6-2-5

Unless specified otherwise, the stand alone capacitor banks shall be with ingress protection rating of IP42 as per IEC standards as minimum.

8-6-2-6

The capacitor banks shall be of multi step automatic switching type rated as per the requirement. General arrangement of the capacitor bank shall be arranged in a systematic manner. The general arrangement shall be in such a way that the incoming switching device is positioned vertically at the bottom corner after leaving sufficient space for incomer cable below switching device. The busbar assembly shall be arranged to position above incoming switching device. The fuses for the capacitor steps shall be fitted on one side of the busbar assembly and interconnected with rigid busbar links. Switching contractors for each step shall be positioned next to the fuses and interconnected by suitably sized heat resistant flexible cables. The capacitor may be positioned next to the contactor or elsewhere at a convenient location inside the cubicle and interconnected to the contactor by heat resistant flexible cables.

8-6-2-7

Capacitor bank where provided as a part of main distribution board, shall be arranged in such a way that each step capacitor assembly including all the protection fuses and switching capacitor shall be assembled on a dedicated plate and shall be assembled inside a modular cubicle, which shall have a bus bar chamber. The fuses in the capacitor assembly shall be interconnected to the main busbar by rigid busbars.

8-6-2-8

Arrangement of the capacitor assembly and the clearance between the components like capacitors,de-tuning reactors etc. shall be strictly as per manufacturer recommendations and shall be well arranged considering the heat dissipation and ventilation arrangement.

8-6-2-9

The live busbar shall be fully shrouded to comply at least to comply with form-2 requirement as per IEC standards.

Page 106


8-6-2-10

Neutral busbar and earth busbar shall be positioned adjacent sides of the incoming switching device facilitating easy connection of the cables.

8-6-2-11

Unless specified otherwise, the capacitor bank shall be always suitable for the wall mounting or floor mounting. Wherever required, the capacitor bank shall be supplied as suitable for top entry cables.

8-6-2-12

Ventilation fan and air inlet filter unit shall be provide for the capacitor banks to facilitate better heat dissipation. The ventilation fan shall be operated by thermostat and also by the switching of the capacitor.

8-6-2-13

Where applicable and/or specified and/or required to comply with local regulations, detuning reactors shall be provided for each steps of the capacitor bank. The detuning reactor shall be integrated in the capacitor bank.

8-6-3

Busbars

8-6-3-1

Busbars shall be tin plated copper, rectangular and rigid construction. The phase busbar shall be arranged systematically and assembled using insulators. The busbars shall be protected poly carbonate shrouds from all sides. The busbar assembly shall be fully shrouded (at least IP20) so that no live parts are accessible. Phase identification shall be done systematically. The rating of the main busbar assembly shall be to suit the incoming switching device rating. The main busbars of the capacitor banks are preferred and recommended to be in separate busbar chamber, wherever applicable.

8-6-3-2

Tin plated copper busbar and earth busbar shall be located on both sides of the incomer. Busbars shall be provided with a suitable termination facility for connecting the main neutral and earth cable. Extra termination shall be provided on the earth bar for the bonding purpose.

Page 107


8-6-4

Switching Devices:

8-6-4-1

Moulded Case Circuit Breaker:

8-6-4-1-1 MCCB as per the capacitor bank ratings and short circuit rating shall be provided in the capacitor bank as the incoming switching device. The construction, characteristics and features of the MCCB shall be same as used in the upstream main distribution boards.

8-6-4-2

Fuses:

8-6-4-2-1 Power fuse shall be provided for each step of capacitor bank to protect against short circuit currents. The fuses shall be rated to suit the capacitor ratings and the de tuning reactor ratings, as applicable. Each phase of the capacitor elements shall be protected individually by fuse. The fuses shall be of GI type and shall comply to the applicable IEC standards.

8-6-4-3

Capacitors:

8-6-4-3-1 Capacitors as per the ratings as shown on the drawings shall be provided in the capacitor bank. The capacitors shall be suitable for operating at temperatures up to +-50 C ambient.

8-6-4-3-2 The capacitor unit shall comply with the applicable IEC standards, the capacitors shall have a rated operational voltage of 400/415V AC 50 Hz, 3Phase and rated insulation level of 6 KV for 1 minute at 50 Hz. The capacitors shall be suitable for withstanding a current overload of at least 30% and voltage overloads of at least 10 % as standard. The tolerance on the capacitor values shall be in the range of 0 to +-10%. The current consumption of the capacitor unit shall not exceed 2.2A/Kvar.

Page 108


8-6-4-3-3 The capacitor shall be of modular design and suitable for vertical or horizontal mounting. The capacitor shall be of dry- type low loss units comprising self heating metalized polypropylene film in the form of a two film roll and shall not require any gas or liquid impregnation. Use of poly chlorinated bi phenols (PCB) and oil as capacitor impregnation will not be permitted.

8-6-4-3-4 The capacitors shall be made of insulating material providing them with double insulation and avoiding the need for ground connection. Plastic enclosures shall be used for the capacitors. The group of elements forming a three phase capacitor unit shall be installed in plastic enclosures. The plastic material used for enclosure shall provide excellent mechanical properties and maximum self extinguishing ratings. Each capacitor shall be provided with three terminal pads and shall not require earth connection.

8-6-4-3-5 The capacitor unit shall be protected by a high quality system which switches off the capacitor if an internal fault occurs. The protection system shall be integrated in to the capacitor element to provide total safety. The protection system shall protect the capacitor against high current faults and low current faults. Protection against high current shall be provide with an HRC cartridge fuse and protection against low currents shall be provided with a overpressure disconnect device and the HRC fuse. The electrical current in the capacitor on both high current and low current faults shall always opened by a standard HRC fuse. The capacitor shall have self healing cahrecteristics.

8-6-4-3-6 The capacitor shall be designed so as to care the fault pressure inside the capacitor element is always limited to a value far lower than the maximum admissible pressure.

8-6-4-3-7 Each capacitor element shall have an inbuilt discharge resistor to fully discharge the capacitor before energizing and recharging the capacitor to minimize the voltage transients.

Page 109


8-6-4-3-8 Whenever the distribution network system is is highly polluted (Gh>Ssc/70), detuning reactors shall be used in conjunction with the capacitor to make an assembly tuned to 190 Hz for a 50 Hz network. The detuning reactors shall be form the same manufacturer of the capacitor. Whenever the system is highly polluted filters shall be used in conjunction with the capacitors.

8-6-4-4

Power Factor regulator:

8-6-4-4-1 Regulator shall be of user programmable type microprocessor based or electronic controller. Regulator shall be suitable for 6 step switching or 12 step switching with various switching programming option. The regulator shall have soft touch keys integral program the unit. The regulator unit in addition to switching the capacitor for automatic compensation shall provide the alarm for over voltage also. The unit shall have a 7 segment LED display unit which shall display the parameters for programming and status. The regulator shall be suitable for flush mount and shall be mounted on the front door of the capacitor bank. The regulator accuracy class shall be atleast 1.5%. The regulator shall be suitable to operating at temperature up to +50C ambient.

8-6-4-4-2 Regulator shall be suitable for the supply voltage, frequency and current input regulator shall be in-sensititive to direction and in sensitive to phase rotation polarity. Regulator shall be with 6 or 12 volt free contacts for capacitor step switching and 1 volt free contact for relay output.

8-6-4-4-3 Regulator shall include momentary no voltage function. Upon no voltage detection the regulator shall disconnect all steps and upon supply restoration for more than 15 ms, automatic reconnector shall be made.

8-6-4-4-4 Regulator shall provide information of cosQ, connected steps, period before switching, step output status (capacitance loss survey), load and reactive current, total voltage harmonic distortion, voltage, temperature, power and voltage harmonic spectrum.

Page 110


8-6-4-4-5 Regulator shall provide alarms and warnings of low power factor, hunting, abnormal power factor, over compensation, frequency not detected, over current, under voltage, over voltage, over temperature, total hatmonic distortion and capacitor overload.

8-6-4-4-6 Power factor setting in the regulator shall be digital and selectable between 0.8 to 0.9 Cap. Regulator shall have capability to automatically search and set the C/K setting, it shall be also possible to program the C/K setting manually.

8-6-4-5

Reactors:

8-6-4-5-1 Detuned reactors shall be provided where high harmonic pollution ( Gh>Ssc/70) is present. Detuned reactors shall be designed to protect the capacitors by preventing amplification of the harmonic present on the network. Detuned reactors shall be connected in series with the capacitors. The capacitor voltage rating shall be increased by 10 % when it is used with the detuned reactors.

8-6-4-5-2 Detuned reactors shall be three phase iron core with copper winding. De tuned reactors shall be natural air cooled, dry type with aluminum foil windings insulated between layers which are impregnated under vaccum.

8-6-4-5-3 High temperature cut off limit switch shall be embedded in the winding of the detuned reactors or disconnect its capacitor from the circuit and the network and reconnect automatically back in the network when temperature is normal.

8-6-4-5-4 Detuned reactors shall be segregated from other equipments, which shall be preferably located at the top of the panel for better heat dissipation and to avoid transfer of the heat to the adjacent components. Whatever detuned reactors are provided forced ventilation shall be provided for the panel.

8-6-4-5-5 Detuned reactor shall at least meet the following technical characteristics: Tolerance:+/-5%

Page 111


Tolerance between phase: L max/L min <1.07 Turning order: 4.3 (relative impedance: 5.4%) Harmonic current spectrum for turning order 4.3: 13=2% 11 15=69% 11 17=19% 11 111=6% 11 Permissible overload fundamental current :1.1 times the normal current (11) Insulation level:1.1KV Test voltage (coil to core):3 KV 1 minute

8-6-4-6

Capacitor switching contractors:

8-6-4-6-1 Contactor provided for capacitor switching (capacitor without de-tuning reactors) shall be special contactor designed for switching capacitors. Special capacitors switching contractors shall be fitted with a block of early make poles and damping resistors, limiting the value of the current on closing to 60 In max. the current limitation at switch on shall increase the life of all the components in the installation, in particular that of the fuses and the capacitor. Contractors shall be at least suitable for 100 operation cycles/ hour. Contactor shall with stand the prospective peak current of 200 In at switch on. Contactor for switching capacitor with de tuning reactors shall be as per manufacturer recommendations.

8-6-5 Labeling : The capacitor bank shall be labeled in English to describe the designation of the capacitor bank as referenced in the drawings. The label shall be fixed in front face of the panel. The label shall be of special white PVC material engraved for the desired text. The text shall be black in color. The label shall be fixed to the door using special PVC rivets. Labels indicating the component numbering as per the schematic diagram shall be provided. Page 112


A drawing pouch shall be provided inside the capacitor bank and as built drawings for the capacitor drawings shall be provided.

8-6-6 Testing : 8-6-6-1

Type test: The capacitor (loose capacitor) and other applicable components shall be type tested in accordance with the IEC standards from a reputed and approved type testing laboratory and certified by a competent authority.

8-6-6-2

Routine test: The panel assembler shall perform the routine test and provide the test certificates as defined in the IEC standards. The routine test shall include but not limited to the following: 1. Inspection of assembly including inspection of wiring and electrical operational test (IEC clause 8.3.1) 2. Dielectric test & insulation resistance test (IEC clause 8.3.2 &8.3.4) 3. Checking of protective measures and of the electrical continuity of the protective circuits(IEC clause 8.3.3) 4. Functional test as per the approved test procedure Routine test certificates and test readings shall be submitted to the consultant engineer for verification.

Page 113


Section -9

Electric Motor , Circuits & Controllers 9-1

The method of starting motors shall restrict the current to limits laid down by the SEWA . All motors over 1 hp shall be provided with means of automatic disconnection from the supply in the event of excess Current flow or drop in voltage of over 15% the limits laid down are as set out below: a) Motors with name plate rating of up to and including 11 kw (15 hp). b) motors with name plate rating of above 11 kw (15 hp).

Motors that fall within category (a) may be connected for direct online starting with over current protection. Motors that fall within category (b) shall not in any circumstances be connected for direct-on-line starting But shall be arranged for reduced voltage starting e.g open or closed transition star/delta starting . Auto Transmission starting , or other approved arrangement. All motors shall be rated at 415 volts 50 HZ three Phase or 240 volts 50 HZ single phase as required . Other voltage will not be accepted . Table 9.1.A details the various insulation classes with their associated maximum operating temperature .The maximum class of insulation acceptable for use in UAE is “B” . Please note that insulation classes Y , A and E are not acceptable in any circumstances . However , when specifying the class of insulation To be used for electric motors or alternators , the actual site condition must be taken into consideration To determine if a higher insulation class is required . E.g. a class B motor will not operate satisfactorily If located in direct sunlight . In general , motors shall be of the drip proof type and be totally enclosed , fan cooled . where motors are required to operate in hazardous area or are required for special purpose

Page 114


The design of motor shall be suitable for this application . The terminal box for all motors shall be weather proof . all motors shall of such construction as to make The temperature as uniform as possible in the different parts of the windings and core during operation , thus avoiding excessive heating at any point . all motors rated at 11 kw (15 hp ) and above shall be fitted With thermostatic control elements within the motor actuating directly the control circuit of the motor and Disconnecting it from the supply in the event of a temperature rise exceeding limits for its insulation class . All motors shall be on their own separate circuit and be provided with control apparatus such as a motor Starter incorporating a suitable device affording protection against excess current in the motor or in the cable between the device and the motor . In addition , all motor starter for 3ph motors shall incorporate a phase failure device which will automatically disconnect the supply from the motor these two protection device shall be manually reset in all cases . the different parts of each motor shall be capable of withstanding the highest mechanical and electrical stresses to which they may be subjected during their operation without any injury , failure or inferior or inferior performance .

9-2 9-3

Motor control panels shall be fitted with an ammeter or ammeter in each motor circuit. The following tables details the type of insulation materials used , for each class for motor construction Together with its maximum winding operating temperature .

Page 115


Table 9-1-A : Specification of the insulation of the motor windings

Class of Insulation Y A E B F H C

Page 116

Specification of the insulation of the Motor windings Cotton , filch , paper , wood , cellulose fiber ,etc Not implemented or immersed in oil Material of class Y but impregnated with natural resins cellulose esters insulating oils , etc , also laminated wood varnished paper cellulose acetate film etc Synthetic resin enamels cotton and paper laminates with formaldehyde bonding Mica , glass fiber asbestos, etc with suitable bonding substances such as built up mica , glass fiber and asbestos laminates Materials of class B with bonding materials of higher thermal stability Class fiber and asbestos material and built up mica with silicone resins Mica , ceramics , glass quarts and asbestos without binders but with silicone resins of high thermal stability .

Max. winding Temp C 90 105 120 130 155 180 180


9-4

Installation of 1-phase motors rated up to 3.7 kw (5 HP) and 3-phase motors up to 110 kw (150 HP) only shall Normally be permitted unless otherwise approved by SEWA . where a large number of motors above 150 HP are Proposed , the advice of SEWA shall be sought on availing a bulk supply .

9-5

All electric motors shall be adequately protected against overload , short circuit , earth leakage and additionally , Against loss of one or more phases , voltage fluctuating , etc . as deemed essential to suit individual applications.

9-6 9-7

Motor upto and including 11 kw (15 HP) may be connected for direct on-line starting with over current protection . All three phase motors over 3 HP and single phase motors above 1 HP shall be providing with current limiting Starting equipment to effectively keep the starting current within the following limits :

Page 117

Type of supply

Rating of motor Max.

Permissible starting current

Single phase

1 – 5 HP

5 times full load current

Three phase

Less than 15 HP


Three phase

15 HP to < 50 HP


Three phase

50 HP and above

1.5 times full load current


9-8

Starter shall be provided with overload relays of the thermal type with automatic compensations for Variation in ambient temperature between 2.80 C and 480 C. The starting equipment to limit the current may consist of any of the following type or other approved By SEWA a) star/delta b) Primary – resistance C) Auto – transformer

9-9

All motors shall be provided with an isolator, for isolating the motor from the supply during periods Of inspection or maintenance. Such means of isolation shall effectively interrupt the supply on all phases. The isolator may be integral with the control gear or separate, but shall be in close proximity to the motor. An emergency stop push button shall be incorporated in the control gear. When motor starting gear is energized from an auxiliary circuit, the circuit shall also be isolated during maintenance. All starters, isolators and push button shall be clearly marked in Arabic and English stating which machine they control and their function. To avoid confusion the words START and STOP instead of OPEN and CLOSED shall be used. Motor and their control gear shall be located in well ventilated situations with adequate space for operation, inspection and maintenance.

9-10 Page 118

Safety and emergency light fitting


Safety lighting to meet operational requirements shall be provided to suit particular applications such as industries, production line, hospital, utility complex, stadiums, shopping centers, auditorium etc The source of supply for safety lighting shall be either maintained or non-maintained type as appropriate to suit individual applications. All electrical switch-rooms and operational areas shall be provided with adequate number of emergency light fittings The safety and emergency light fittings installed shall comply with BS 5266 and shall be rated for a period not less than 3 hours continues operation. The light fittings shall also incorporate necessary battery and charger within . the safety light fitting shall also incorporate sign in Arabic and English such as EXIT and directional arrows as applicable to individual locations

9-11

Standby generator Installation and connection of standby generators in consumer’s installation for the purpose of maintaining power supply under mains failure conditions shall be permitted only with prior approval from SEWA . and compulsory for building above its stories. The change-over circuit breaker or isolator shall have 4-Poles for 3-phase supply and 2-Poles for 1-phase supply to ensure that the phases and neutral of the two systems remain separate and distinct. The installation shall ensure that there will be no possibility to parallel generator supply with SEWA supply under any circumstances or conditions > Adequate mechanical and electrical interlock between the incomer circuit breakers or isolators of both generator and SEWA supplies shall be provided . The full details of the equipment, circuit and wiring diagrams, details of essential loads, etc shall be submitted to SEWA for approval before commencement of the work.

Page 119


APPENDIX – 1 SPACING OF SUPPORTS FOR TRUNKING CONDUIT AND CABLES

Table no 1 Maximum number of cables that may be installed in surface Mounted metal or PVC trunking Cable 1.5 2.5 size Trunking 1/1.38 7/7.67 size 38X38 71 58 50X38 92 76 50X50 123 98 75X50 185 148 75X75 278 221 100X50 247 197 100X75 370 296 100X100 494 394 150X50 370 296 150X100 741 592 150X150 112 888 225X100 112 888

Page 120

4

6

10

16

25

7/0.85

7/1.04

7/1.35

7/1.7

7/2.14

39 50 67 101 152 135 203 271 203 406 609 609

30 39 52 79 118 195 158 211 158 316 475 475

19 25 33 51 76 67 101 135 101 203 305 305

14 18 24 37 55 49 74 98 74 148 222 222

9 12 16 24 37 39 49 66 49 99 148 148

35

50

70

95

19/1.53 19/1.78 19/2.14 19/2.52 7 9 12 18 28 25 37 50 37 75 112 112

5 6 9 13 20 18 27 37 41 55 83 83

4 5 7 10 16 14 21 28 32 42 64 64

3 3 5 7 11 10 15 21 23 31 47 47

mm2 No. & dia mm


Table no 2 Maximum number of cables that may be installed in under Floor metal or PVC trunking Cable size Trunking size

1.5

2.5

1/1.38 7/7.67

4

6

10

16

25

7/0.85

7/1.04

7/1.35

7/1.7

7/2.14

35

50

70

95

19/1.53 19/1.78 19/2.14 19/2.52

50X25

48

38

26

20

13

9

6

4

3

2

2

75X25

72

57

39

30

19

14

9

7

5

4

3

100X15

96

76

52

41

26

19

12

9

7

5

4

150X25

144

115

79

61

39

28

19

14

10

8

6

50X38

72

57

39

30

19

14

9

7

5

4

3

75X38

108

86

59

46

29

21

14

11

8

6

4

100X38

144

115

79

61

39

28

19

14

10

8

6

150X38

216

172

118

92

59

42

28

21

16

12

9

Page 121

mm2 No. & dia mm


Table no 3 Capacity of both galvanized metal and high impact Rigid PVC conduits Conduit size Conductor size mm2

No. & dia of wires mm2

20 mm

25 mm

1.5

1/1.13

11

18

2.5

1/1.78

8

14

2.5

7/0.67

7

12

4

7/0.85

5

9

15

6

7/1.04

4

7

12

10

7/1.35

3

4

7

16

7/1.7

2

3

5

25

7/2.14

2

4

35

19/1.53

2

50

19/1.78

2

The size of conduit selected shall allow drawing the cables freely within, without damaging the insulation.

Page 122

32 mm


Table no 4 Spacing of support for trunking , conduits and cables Maximum spacing of clips , cleat or saddles Over Dia of Cables

Non armored rubber PVC or lead sheathed cables armored cables

Armored Cables

Not exceeding 10 mm

300

400

Exceeding 10 mm but not exceeding 20 mm

300

400

350

450

Exceeding 20 mm but not exceeding 40 mm

400

500

450

600

Exceeding 40 mm

800

1000

1000

1200

Page 123

Mineral insulated copper Sheathed with or without PVC covering 600

800

900

1200


APPENDIX -2 EARTH LEAKAGE PROTECTION

Table no 5 Minimum size of earth continuity conductors and bonding leads

Page 124

Cross sectional area Largest associated circuit

Cross sectional area of earth continuity conductor mm2

2.5 4 6 10 16 25 35 50 70 95 120 150 185 240 300 400

2.5 4 6 10 16 16 16 25 35 50 70 95 95 120 150 240

Cross sectional area of bonding lead mm2 1.5 2.5 2.5 2.5 2.5 6 6 6 16 16 16 16 50 50 70 70


Table no 6 Recommended Value of operating current ELCB/RCCB/RCD in consumer installation

Sr. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Page 125

Circuit /Equipment / Apparatus 13 A switched socket outlet Water heater / coolers Refrigerator/washing machine Domestic water pump Under water light 15 A switched socket outlet ( general purpose ) General lighting Flood lighting Window /split type air conditioner FCU/AHU/VAV Package type A/C unit Chiller Irrigation pump Electric cooker Industrial machine Elevator / escalator Neon sign

Rated operating current mA 30 30 30 30 10 10 30 30/100 100/300 100 100 100/500/1000 100 100 100/300 300/500 300


Notes : 1) Grouping of circuits under one ELCB/RCCB is permitted for lighting circuits general purpose switched socket outlet single phase machine /appliances etc in such cases maximum number of circuit proposed under such group shall be suitably selected considering the type of project such as residential , commercial ,industrial etc and the possible interruption . 2) Where ever uninterrupted power supply is required for equipment /circuit of fire protection drainage etc suitable earth leakage detection system with indication and /or alarm is permitted . 3) For industrial installation which are designed with coordinated operational system of plants and machines the earth leakage protection shall be suitably selected considering the safety and operational requirements.

Page 126


APPENDIX -3 CURRENT RATING FOR SINGLE AND MULTI-CORE CABLES The following factors have been used in determining the maximum current capacity of cables to be used within the sharjah emirate with copper conductors and manufactured to comply with : *) BS 6346 *) BS 6004 *) BS 5467 1) Where cables are laid in the ground (in pipes of direct) – depth of lay is 600 mm . 2) Ground temperature of 35 3) Thermal resistivity of the ground 3.0 C m/w 4) Where cables are installed above grounds level and not exposed to the outside ambient conditions air temperature Taken as 45 C. 5) Where cable are installed above ground level and exposed to the outside ambient conditions air temperature taken as 50C 6) All current ratings apply only where the cables have closed excess current protection . 7) The current ratings for cables having aluminum conductors have not been included in these tables aluminum Conductors shall not be used . 8) Cables not manufactured to the above British standards are not included in these tables and therefore the current Ratings will not apply.

Page 127


Table no 7 Recommended size of cables for use in fixed wiring installation for general purpose and in normal situations in sharjah emirate Cable size

1.5

2.5

4

6

10

16

25

35

50

70

95

120

150

185

240

300

400

Single core PVC insulated non-armoured , stranded copper conductors (BS 6004 & BS 6346) Ampere rating VD Mv/A/M

10

15

20

25

30

40

50

60

80

100

125

150

23

14

8.8

5.9

3.5

2.2

1.4

1

0.84

0.62

0.48

0.42

0.39

0.35

Multi Core Aromoured PVC Insulated Copper Conductor(BS 6346) Ampere rating VD Mv/A/M

10

15

20

30

40

50

60

80

100

125

160

180

200

250

300

350

400

24

15

9.1

6

3.6

2.2

1.5

1

0.81

0.57

0.42

0.34

0.29

0.24

0.20

0.18

0.17

Multi Core Aromoured XLPE Insulated Copper Conductor(BS 6346) Ampere rating VD Mv/A/M

Page 128

50

60

80

100

125

160

200

225

250

300

350

400

4

2.6

1.5

1.2

0.87

0.61

0.45

0.36

0.29

0.24

0.20

0.18


Page 129

Sharjah Regulations

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