Sharjah Regulations

SEWA Regulations for Electrical Connection

Rules and Regulations of Electrical Connection

Sharjah Electricity & Water AuthorityDirectorate of Transmission and DistributionPage 1


CONTENTSSL NO 1 2 3 4 5 6 7 8 9 10 11 12 General Requirements Definitions Requirement for Safety Substation, Services Arrangement & Distribution Boards Conductor Earthing Arrangements And Protective Conductor Installation Details SubFinal Sub-circuit Power Factor Correction Equipment / Capacitor Bank Electrical Motor , Circuits & Controllers AppedixAppedix-1 Spacing Of Supports For Trunking , Conduits And Cables AppedixAppedix-2 ix Earth Leakage Protection AppedixAppedix-3 MultiCurrent Rating For Single And Multi-core Cables TOPIC

PAGE3 11 26 31 53 68 92 100 114 120

124

127

Page 2


Section -1

GENERAL REQUIREMENTS1-1 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 andapproval 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 arenot 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 forevery 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.

Page 3


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.

Page 4


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 TR KVA1500 1000 500 250

MDB I/C60KA 55KA 45KA 40KA

MDB O/G55KA 50KA 45KA 35KA

SMDB I/C35KA 35KA 35KA 35KA

SMDB O/G25KA 25KA 25KA 25KA

Page 5


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 52C and the minimum 2C. The maximum ground temperature in 35C at a depth of 1 meter and the maximum sea water temperature is 40C 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.

Page 6


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.

Page 7


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.

Page 8


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.)

Page 9


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.

Page 10


Section -2

DEFENITIONSAccessory: 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. Arms 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 notnecessarily 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 commonpotential.

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 ofaccess.

Page 11


Bunched: Cables are said to be bunched when two or more are contained within a single conduit, ducting, or trunking or, if notenclosed, 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 thelength 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 notpermit 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 orconduit 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 andplug.

Cable Ducting :A manufactured enclosure for material or insulated material, other than conduit or cable trunking, intendedfor 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 lessthan 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% ofthe plan area.

Page 12


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

Cable tunnel: An enclosure containing supporting structures for conductors and/ or cables and joints and whose dimensionsallow 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 constructionand 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 supplycables 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 cartridgeusually 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 sameprotective 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 theDistribution Company.

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

Page 13


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 automaticallybreaking, 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 adefined sequence.

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

Class 1 Equipment: Equipment in which protection against electric shock does not rely on basic insulation only. But whichincludes 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 whichadditional 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 eachother. 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, butnot inserted laterally.

Page 14


Connector: The part of a coupler or of an appliance coupler which is provided with female contacts and is intended t beattached 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 thatinstallation.

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 specificconditions 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. Ormotive power.

Danger: risk of injury to persons (and live stock where expected to be present from1. 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, accumulateprocess and store data acceptable and divulgence of data may or may not be by electronic means.

Page 15


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 oneor 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 drawnin.

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.

Page 16


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 electricallysound. 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 surroundedthroughout 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 maintainedat 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 othermeans of earthing.

Electric Shock: A dangerous physiological effect resulting from the passing of electrical current through a human body orlivestock.

Page 17


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

Electrical independent earth electrodes: Earth electrode located at such a distance from one another that the maximumcurrent 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 anelectrical 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, orproperty.

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

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

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

Extraneous Conductive Part: Extraneous- conductive part liable to introduce a potential generally earth potential, and notforming part of the electrical installation.

Page 18


Fault: A circuit condition in which current flows through an abnormal or un intended path. This may result from an insulationfailure 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 theconnection 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 theelectrical 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 SELVhave been applied.

Fuse: A device that by the fusing of one or more of its specially designed and proportioned components, open the circuit inwhich 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 thefuse has operated and before the fuse is put back in to service.

Page 19


Gas installation pipe: Any pipe not being a service pipe (other than any part of a service pipe comprised in a primary meterinstallation) 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 vergeand 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 distributionboards 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, risingfor 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 inelectrical shock.

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

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

Page 20


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 notproduce 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 partsnecessary 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 aluminaire 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 withassociated 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 functionalearthing any, to the means of eatrthing.

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

Page 21


Motor caravan: self propelled leisure accommodation vehicle used for touring, designed to meet the requirements for theconstruction 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 electricalenergy. 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 aspecified 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, aprotective conductor or a pen conductor. The term also means the equivalent conductor of a DC system unless otherwise specified in the regulation.

Page 22


PLUG: A device provided with contact pins which is intended to be attached to a flexible cable, and which can be engaged witha 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 thesupply 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 negligibleimpedance 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 againstelectric 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 thenominal 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 shockequivalent to double insulation under the conditions specified in relative standard.

Page 23


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 inthe electrical insulation.

Residual Current device: A mechanical switching device or association of devices intended to cause the opening of thecontact 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 significantvoltage gradient may exist.

Restrictive conductive location: A location comprised mainly of metallic or conductive surrounding parts, within which itis 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 totheir 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 faultcannot give rise to the risk of electrical shock.

Page 24


Shock Current: A current passing through the body of a person or livestock such as to cause electric shock and havingcharacteristics likely to cause dangerous effects.

Short circuit current: An over current resulting from a fault of negligible impedance between live conductors having adifference in potential under normal operating effects.

Simultaneously Accessible parts: Conductors or conductive parts which can be touched simultaneously by a person or inlocations 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 thatelectricity may create.

Socket- outlet; A device, provided with female contacts, which intended to be installed with the fixed wiring, and intended toreceive 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 abranch 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.

Page 25


Stationary Equipment: Electrical equipment which is either fixed or equipment having a mass exceeding 15 KG and notprovided 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 theuse of the highway.

Supplementary insulation: independent insulation applied in addition to basic insulation in order to provide protectionagainst 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 ownedotherwise 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 ofcarrying 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 definitesequence.

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

Page 26


System: An electrical system consisting of a single source of electrical energy and an installation. For certain purpose of theregulations, 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 exposedconductive 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 supplysafety 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).

Page 27


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

Page 28


Section -3

REQUIREMENT FOR SAFETY3-1Good 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

Page 29


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 beotherwise 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 strengthand protection.

3-6 Every electrical circuit and sub circuit shall be protected against excess current by fuses, circuit breakers, or other similardevices which: Will operate automatically at current values at which are suitably related to the safe current ratings of the circuit and

Page 30


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 earthedmetal, 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 offposition. 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 asto 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 allapparatus 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 readilyoperated and so placed as to prevent danger.

Page 31


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, andwhere 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 inmasonry 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 hasascertained 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.

Page 32


3-18 Where for construction purposes or otherwise. A temporary supply is required; the temporary electrical installations shallcomply 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.

Page 33


Section -4

SUBSTATIONS. SERVICES ARRANGEMENT, AND DISTRIBUTION BOARDS4-0 4-1 SubstationSEWA 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. 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). 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. 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. 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

4-2

4-3

4-4 4-5

Page 34


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 Roomssupplying 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.

4-6-1 All low voltage main switch room shall be air conditioned by means of extending the air condition duct work system

4-6-2 Services associated with air conditioning water, drainage, and telephone shall not be allowed to pass through. HV Switchrooms, 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 thebuilding. 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 roadside, 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

Page 35


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 forthose 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; themaximum 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 ismanufactured. 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 besubmitted 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.

Page 36


4-8-6 arrange ment of apparatus on main switch board: All Apparatus shall be so placed on a switchboard to ensure ampleroom 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.

Page 37


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

4-8-8 Main SwitchesThe 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 maincontrolling 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 4-8-13 4-9Al 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. 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. Metering:

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

Page 38


4-9-2 Current transformers of class 21 metering type shall be installed on all type of main switch boards where the loaddictates 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 barimmediately 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 panelmanufacturer to comply with SEWA requirements. The following standard sizes of CTs are used:

200/5 300/5 400/5 500/5 600/5 800/5 1200/5 1600/5 2000/5 2500/5

5 VA 5 VA 5 VA 5 VA 5 VA 5 VA 5 VA 5 VA 5 VA 5 VA

Page 39


4-9-5 All CTs installed in cubicle switch board by manufacturer shall be pre wired to ten way terminal block located in themetering 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 minimumdimensions 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 voltmeterreading 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 beconnected 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.

Page 40


4-11 Sealing of apparatus: All apparatus , main switches, busbars, sub main switches, rising main distribution systems onthe 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. Thebusbar 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 rigidconstruction. 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 thetype 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.

Page 41


4-12-4 Distance between busbars supports for busbar system and the distance between different phases of busbar system shallb 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 ormiddle 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. 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.

4-12-7

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. 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.

4-12-9

Page 42


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. 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.

4-12-11 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. Links: links shall be marked to indicate whether they are live or neutral.

4-12-15 4-12-16

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.

Page 43


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.

Page 44


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 Rating KVA 250 500 1000 1500 (KA) 35 45 55 65 (for duration of 3 seconds minimum) (MVA) 18 18 31.5 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.

Page 45


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.

Page 46


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.

Page 47


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.

Page 48


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 theapparatus 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: 4-16-1Up 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. 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.

4-16-2 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. 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.

4-16-4

Page 49


Installation Demand Cable type(19m length) 2C PVC/SWA/PVC for single Phase service only 4C PVC/SWA/PVC $C XLPE/SWA/PVC 40A 16mm2 16mm2 16 mm2 80 A 35mm2 25mm2 100A 50mm2 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 thepremises 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.

Page 50


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.

Page 51


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 circuitbreakers.

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

Page 52


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.

Page 53


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 earthresistance 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. 5-4-5Metallic 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.

Page 54


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 5-5-1

Earth conductorsEarthing 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 Protected against corrosion As required clause 16mm2 Fe 25 mm2 Cu Protected against corrosion 50mm2 Fe Mechanically unprotected 16mm2 Cu

5-5-2 the connection of an earthing conductor to an earth electrode shall be soundly made and electrically satisfactory where aclamp 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 areasThe 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 byFault 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 Final temperature Material conductor Copper Aluminum steel 143 95 52 176 116 64 166 110 60 160C XLPE EPR 250C Butyl Rubber 220C

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 Initial temperature Final temperature Material of conductor Copper Aluminum 115 76 143 94 134 89 160C 160C XLPE EPR 250C 250C Butyl Rubber 220C 220C


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 Temperature max. Copper k Temperature max. Aluminum k Temperature max. Steel k 500 C 228 300 C 125 500 C 82

Normal condition 200 C 159 200 C 105 200 C 5850

Fire risk 150 C 138 150 C 91 150 C


Page 60


5-8-1 The cross sectional area of the protective conductor shall not be less than the appropriate valueShown 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 ) S 16 16 < S 35 S> 35

Minimum cross sectional area of the Corresponding protective conductor SP (mm2 ) S 16 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 doesnt 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.

Page 61


5.9.1

Types of protective conductor Dele

Sharjah Regulations

Documents

Transcript of Sharjah Regulations