The Electricity Wiring Regulations 2007Issued by:the Regulation and Supervision Bureaufor the Water, Wastewater and Electricity Sectorin the Emirate ofAbu Dhabiwww.rsb.gov.aeRevision 1January 2009Tel: +971 2 642 6777 Fax: +971 2 642 4217P.O. Box: 32800Abu Dhabi, U.A.Ee-mail: bureau@rsb.gov.aewww.rsb.gov.aeRegulation and Supervision Bureaufor the Water, Wastewater and Electricity Sector in the Emirate ofAbu DhabiThe Electricity Wiring Regulations 2007 (Revision 1) 3TheRegulationandSupervisionBureau(theBureau)isestablished inAbuDhabilawtooverseetheeconomicandtechnicalactivities of electricityandwatercompaniesthatarelicensedtooperateinthe Emirate ofAbu Dhabi. In addition to its duties over licensed companies, the Bureau has certain responsibilitiestowardsthegeneralpublic,includingtheassuranceofsafe and effcient electricity and water supplies to customers and these Regulations have been produced with this primary aim in mind.The Regulations promote the installation and operation ofsafe electricity wiringsystemsincustomerspremisesandarebasedonthegeneral principles defned in British Standard BS 7671 (otherwise known as the IEE Wiring Regulations, UK), which are also similar to the International StandardIEC60364.Suchprincipleshavebeencommonpracticein Abu Dhabi and were adopted in previous documents, including the frst Wiring Regulations issued by the old Water and Electricity Department (WED) in 1972.ThenewRegulationsarelessprescriptivethanpreviousdocuments, but provide a closer defnition oftechnical parameters compared with BS 7671. In addition they take account ofthe physical environment in Abu Dhabi and the skills and language diversity ofthe region.FollowingfeedbackfromvariouspartiestheBureauissuedan AmendmenttotheRegulationsinNovember2008whichisnow incorporated in Revision 1 ofthe Regulations, effective 1 January 2009. TheAmendment(No.1)isalsoavailableasaseparatedocumentthat may be downloaded from the Bureaus website, www.rsb.gov.ae.Nicholas CarterDirector General1 January 2009ForewordThe Electricity Wiring Regulations 2007 (Revision 1) 4TheBureaugratefullyacknowledgesthecontributionsandcomments provided by the following organisations:Government organisations:Abu Dhabi Water and Electricity AuthorityAl Ain Distribution CompanyAbu Dhabi Distribution CompanyAbu Dhabi MunicipalityAl Mirfa Power CompanyDubai Electricity and Water Authority (DEWA)Dubai Municipality (Central Laboratory)Sharjah Electricity and Water Authority (SEWA)Federal Electricity and Water Authority (FEWA)Emirates Standardisation and Metrology Authority (ESMA)Private organisations:Benchmark Electrical Safety Technology LtdParsons International LtdSchneider Electric FZEVoltas Limited, UAEIan Banham AssociatesPell Frischmann ConsultantsGibb LtdPower Economy Middle EastWSP Middle East LtdGHD Ltd (Aust/UAE)ABB Industries LLC (Dubai)Power Connections LtdReed Smith Richards ButlerBritish Standards InstituteElectrium LtdInparticular,theBureauwishestoacknowledgepermissiongranted by the Institute ofEngineering Technology and the British Standards Institutefortheuseinthisdocumentof dataandinformationtaken from BS 7671 (The Electricity Wiring Regulations, UK).AcknowledgementsThe Electricity Wiring Regulations 2007 (Revision 1) 5These Regulations use the following numbering system:Chapters:are referenced by integers (e.g. 1, 2, 3, etc)Regulations:arereferencedbyonefullstopbetweennumbers (e.g. 1.1, 1.2, etc)Clauses:arereferencedbytwofullstopsbetweennumbers (e.g. 3.1.2, etc)Notes:are indicated below the clause in square brackets and italic text. For example, [Note: this clause does not apply to Installations that have been ]Amendments:amendedtextishighlightedbyaredmargin(as amended in Revision 1, January 2009)Document numberingChapterNoteRegulationClauseAmended text(Revision 1)The Electricity Wiring Regulations 2007 (Revision 1) 6Revision NumberDate Prepared by:Checked by:Issued to:ED/R01/010Issue 1Dec 2007 T Khan L Hill PublicationED/R01/010Revision 1Jan 2009 T Khan L Hill PublicationList ofrevisionsThe Electricity Wiring Regulations 2007 (Revision 1) 7Table ofcontents1Foreword3Acknowledgements4Document numbering5List ofrevisions61Introduction111.1Citation and commencement111.2Purpose and document structure111.3Scope and enforcement122Defnitions152.1Interpretation153General principles and safety requirements273.1Technical standards, materials andworkmanship273.2Approval ofinstallations283.3Extensions, alterations and repairs293.4Licensed contractors293.5Requirements for safety303.6Labelling and identifcation313.7Environmental conditions334Electricity supply intake and supplyparameters354.1Electricity supply parameters354.2Electricity supply intake364.3The customer connection point384.4Multiple occupancy premises394.5Metering requirements39The Electricity Wiring Regulations 2007 (Revision 1) 85Protection415.1General principles415.2Overload and short-circuit protection415.3Electric shock protection435.4Earth leakage protected systems445.5Earthed equipotential bonded systems475.6Isolation and switching505.7Insulation516Earthing536.1General principles536.2Systems ofearthing536.3Main earth terminal546.4Earth electrodes556.5Earth conductors566.6Exposed-metallic-parts586.7Earth fault loop impedance596.8Lightning protection606.9Functional earthing and highleakage currents617Selection ofcomponents and installation requirements637.1Plugs and socket-outlets637.2Switches and isolators657.3Lighting667.4Conduit, trunking and cable trays687.5Cables717.6Final circuits757.7Busways, bus ducts and busbar risers767.8Distribution boards777.9LV switchboards808Inspection, testing and certifcation838.1Electrical installation certifcates838.2Routine inspection and testing85The Electricity Wiring Regulations 2007 (Revision 1) 99Special locations and systems879.1Separated extra-low voltage (SELV)879.2Protective extra-low voltage (PELV)889.3Bathrooms and similar locations889.4Swimming pools909.5Water fountains919.6Construction sites and outdoor supplies939.7Street lighting9410Capacitors and motors9510.1General requirements9510.2Specifcations for capacitors9610.3Electric motors and starters9810.4Standby generators99 Appendices101Guidance Notes191The Electricity Wiring Regulations 2007 (Revision 1) 10The Electricity Wiring Regulations 2007 (Revision 1) 1111.1Citation and commencement1.1.1TheseRegulationsshallbecitedastheElectricityWiring Regulations 2007 (Revision 1).1.1.2These Regulations take effect from 1 January 2008, and for amendmentsincorporatedinRevision1,from1January 2009.1.1.3TheseRegulationsareissuedbytheRegulationand Supervision Bureau through the powers vested in it under Article 62 ofLaw No (2) of1998 (including amendments and re-enactments thereof ).1.1.4These Regulations supersede the following regulations:(a)ADWEA Wiring Rules and Regulations (3rd Edition2003);(b)WED Regulations for Electrical Installation Works(1980); and(c)Earth Leakage Protection Regulations (2001).1.2Purpose and document structure1.2.1The purpose ofthese Regulations is to establish standards andprinciplesthatpromotethedesign,constructionand operation ofsafe and effcient systems ofwiring in buildings and other Premises.1.2.2Themainpartof thisdocumentisstructuredinto chapters,regulationsandclauses,seeillustrationon page 5.Regulations and clauses are mandatory. Notes which are included below clauses, in italic text, are for guidance, clarifcation or provide supporting technical information.1.2.3The second part ofthis document consists ofAppendices, whichcontainmandatoryinformation,andGuidance Notes which contain supporting information.IntroductionThe Electricity Wiring Regulations 2007 (Revision 1) 1211.3Scope and enforcement1.3.1TheseRegulationsapplytoallDistributionCompanies, Customers,propertyOwners,LicensedContractors,or anyotherpersonsinvolvedinthedesign,construction, installation,maintenanceoroperationof Electrical Installations in any Premises or other place where there is an electricity supply provided by a Distribution Company. Suchlocationsinclude,butarenotlimitedto,domestic, commercial and industrial premises, public buildings, parks, farms, temporary supplies, construction sites, wedding tents, outbuildings, caravans, street lighting and traffc signs.1.3.2Thescopeof theseRegulationsdoesnotincludethe electricitydistributionnetworksbelongingtoDistribution Companies, except such equipment that is required at the interface with Customers, as detailed in these Regulations.[Note:requirementsgoverningDistributionCompanies networksarecoveredundertheElectricitySupplyRegulations 2007, as well as other relevant Licences, codes and standards.]1.3.3TheseRegulationsshallapplytoallnewElectrical Installationsconstructedfollowingthecommencement date (clause1.1.2).Requirements for extensions, alterations andrepairstoexistingInstallationsarecoveredunder Regulation3.3.[Note:wherethedesignofanInstallationhasbeencompleted before the date of commencement of these Regulations advice must be sought from the Distribution Company before construction is commenced.]1.3.4ForElectricalInstallationsconstructedbeforethedateofcommencement, the clauses listed in Appendix A4(a) shall either not apply, or shall apply after 1 January 2010 or, ifearlier, at the time ofany extension work or re-certifcation ofa Premises, as indicated in Appendix A4(a).The Electricity Wiring Regulations 2007 (Revision 1) 131 1ntroduction1.3.5TheseRegulationsshallbeenforcedbytherelevant DistributionCompaniesintheEmirateof AbuDhabi,in accordancewithprocedureswhichshallbepublishedby theDistributionCompanyandapprovedbytheBureau. See Regulation 3.2.1.3.6CompliancewiththeseRegulationsrequirescompliance with other relevant technical standards, see Regulation3.1. ReferencestoBritishStandardsorotherstandardsmeans the current edition ofthe standard cited or its replacement. For existing Installations clause1.3.4 applies.1.3.7FailuretocomplywiththeseRegulations,oranypart thereof, shall be deemed as contrary to the Law and subject to punishment by the imposition ofa fne. Any such failures will be addressed in accordance with the Law underArticle 65(5) (notices served by the Bureau) and Article 66 (failure tocomplyandimpositionof fnes).Actionmaybetaken againstanyDistributionCompany,Customer,Owner, LicensedContractororotherpersontowhichthese Regulations apply.[Note: see Appendix A4(b) for a list of relevant Articles of Law No (2) of 1998.]1.3.8Relaxation ofany ofthe requirements ofthe Regulations shallbeapprovedbytheBureauuponwrittenrequestby anyDistributionCompany,Customer,propertyOwner, LicensedContractororotherperson.Suchrequestsmay bereferredtoadispensationpanelestablishedforsuch purpose by the Bureau.1.3.9In the event ofa dispute between any parties mentioned in clause 1.3.1,themattermaybereferredtotheBureauto adviseasolutionorrecommendedaction.Thisdoesnot preclude any party referring a matter to the relevant Court ofAbu Dhabi. The Electricity Wiring Regulations 2007 (Revision 1) 1411.3.10These Regulations and the rights and duties ofany parties thereundershallbegovernedby,construedandapplied inaccordancewiththeLawsof AbuDhabiEmirateand the Federal Laws ofthe UAE as applied by the Courts ofAbu Dhabi. The Electricity Wiring Regulations 2007 (Revision 1) 1522.1InterpretationWords which are defned under this section are used in the Regulations beginningwithcapitalletters.Forexample,allEarthConductors within a Premises shall be ....Termsincommonusearenotdefnedhereandnormaldictionary defnitions apply (e.g. circuit-breaker, plug, conduit). Words and expressions other than those described in this section, which aredefnedintheLaw,shallhavethemeaningsascribedtothemin the Law.Wordsusingthesingularorpluralnumberalsoincludethepluralor singular number, respectively.2.1.1Accessory:adevice,otherthancurrent-usingequipment, associated with an Electrical Installation.2.1.2Appliance: an item ofcurrent-using equipment.2.1.3ArmsReach:azoneof accessibilitytotouch,extending from any point on a surface where a person may stand or moveabout,tothelimitswhichsuchpersonmayreach withoutassistance(i.e.withoutanytoolorladder,etc). Suchadistancemaybetakenas2.5mheightfromthe standing surface, and 1.25 m horizontally from the standing position.2.1.4BondingConductor:seeEquipotentialBonding Conductor. 2.1.5Bureau:theRegulationandSupervisionBureauforthe Water, Wastewater and Electricity Sector in the Emirate ofAbu Dhabi, as established under the Law.2.1.6CableTray:acablesupportconsistingof acontinuous basewithraisededgesandnocovering.Acabletrayis considered to be perforated where more than 30% ofthe material is removed from the base.DefnitionsThe Electricity Wiring Regulations 2007 (Revision 1) 1622.1.7CableTrunking:amanufacturedenclosureforthe protection ofcables, normally ofrectangular cross-section, ofwhich one side is removable or hinged.2.1.8Category1Circuit:aCircuit(otherthanafrealarmor emergencylightingCircuit)operatingatLVandsupplied from the Distribution Company.2.1.9Category 2 Circuit:aCircuit(otherthanafre alarmoremergencylightingCircuit)whichsupplies telecommunicationsequipment(suchastelephones, intruder alarms, data transmission, call bells, etc).2.1.10Category3Circuit:afrealarmoremergencylighting Circuit.2.1.11Circuit: a set ofphase and neutral conductorsinstalled as a group to supply power to a location, and which originate fromoneProtectiveDevice.Thefollowingarerelated defnitions:(a)RingCircuit:aCircuitwhichiswiredfroma singleProtectiveDevice,beingrunthroughan area to be supplied (via appropriate socket-outlets, connectors,etc)andreturningbacktothesame ProtectiveDevice,thusforminganelectrically continuous loop;(b)RadialCircuit:aCircuitwhichiswiredina radial or branch confguration, emanating from a Protective Device, to the area to be supplied;(c)Spur Circuit: a Circuit which is wired in a radial or branch confguration from any point on a Ring Circuit;(d)Final Circuit: a Circuit which supplies Appliances (normallyviasocket-outletsorothertypesofconnectors); andThe Electricity Wiring Regulations 2007 (Revision 1) 172 Defnitions(e)Distribution Circuit: a Circuit connecting between DistributionBoards(mayalsobereferredtoasa sub-Circuit).2.1.12Circuit Protective Conductor: see Earth Conductor.2.1.13Class I Equipment: equipment which includes a means for connectionof Exposed-Metallic-Partsof theequipment to the Earth Conductor, thus providing protection against electric shock in case offailure ofthe basic insulation ofthe equipment or other fault condition.2.1.14Class II Equipment: equipment which does not include a meansforconnectiontoanEarthConductor,andwhich provides supplementary insulation in addition to the basic insulation ofthe equipment such that a breakdown ofthe basicinsulationwillnotpresentadangerousvoltageon Exposed-Metallic-Parts(alsoknownasDoubleInsulated equipment).Class II Equipment is required to comply with BS 2754. See Appendix A18(b).2.1.15ClassIIIEquipment:equipmentinwhichprotection againstelectricshockreliesonsupplyatSELVandin which voltages higher than SELV are not generated in the equipment, see BS 2754.2.1.16CompetencyLicence:alicenceissuedbyaDistribution Company to a Licenced Contractor assessed as competent for work on Electrical Installations.2.1.17ConnectedLoad:theaggregateloadof Appliancesand other electrical equipment at a Premises, summated using themethoddescribedunderclause 3.2.5.SeeGuidance Note G2.2.1.18ConsumerUnit:anintegratedunitwhichacceptsthe incomingsupplytoadomesticPremises,orothersimilar installation, and contains the main isolating device.The Electricity Wiring Regulations 2007 (Revision 1) 1822.1.19Customer:anyperson,corporatebody,orcompanywho hasanagreementwithaDistributionCompanyforthe supply ofelectricity.2.1.20Customer Connection Point (CCP):the point which defnes the boundary between the Customers Installation and that of theDistributionCompany(alsoknownasthePointofSupply).This point will normally be at the incoming cable ofthe Main Distribution Board and before the main circuit-breaker, see Appendix A13. In special cases, an alternative defnition ofthe Connection Point may be agreed between the Customer and the Distribution Company.2.1.21Danger:risk ofinjury to people or animals from fre, electric shock, burns, explosion or from mechanical movement ofelectrically controlled equipment, or the risk ofdamage to property.2.1.22DirectContact:thecontactwithelectricitybyaperson (accidentalorotherwise)throughthephaseorneutral conductorsof anInstallationorAppliance,leadingtoan electric shock, see Guidance Note G4(a).2.1.23DistributionCompany:acompanyorbodyholdinga Licence from the Bureau, pursuant to the Law. 2.1.24DistributionBoard:anassemblydesignedforhousing isolation switches and Protective Devices and for connecting multipleCircuits,includingtheirassociatedneutraland Earth Conductors. The following are related defnitions:(a)MainDistributionBoard(MDB):theDistribution BoardwhichacceptsthemainincomingLVsupply fromtheDistributionCompanyorCustomers transformer;(b)SubDistributionBoard(SDB):anyDistribution BoardwhichisneitheraMainDistributionBoard nor a Final Distribution Board; and(c)FinalDistributionBoard(FDB):aDistribution Board which supplies Final Circuits only.The Electricity Wiring Regulations 2007 (Revision 1) 192 Defnitions2.1.25DiversifedLoad:theloadataDistributionBoard,at the Supply Intake or at any other point in an Installation, calculated using diversity factors as illustrated in Appendix A20(f) and Guidance Note G2.2.1.26Double Insulated Equipment: see Class II Equipment.2.1.27Earth:theconductivemassof Earth,whoseelectrical potential(voltage)atanypointisconventionallytakenas zero.The following are related defnitions:(a)CustomerEarthedSystem(TT):asystemofsupplywheretheCustomerprovidesaMainEarth TerminalfortheInstallation,whichisconnected toasuffcientnumberof localEarthElectrodesto provideamaximumEarthResistancemeasuredat theCustomersMainEarthTerminalof notmore than 10 Ohms.(b)DistributionCompanyEarthedSystem(TN-S):a systemof supplywheretheDistributionCompany provides a connection to the Customers Main Earth Terminal,usingthedistributionnetworkEarthing system, normally via the armouring or metallic sheath ofthe main incoming supply cable.(c)DistributionCompanyEarthedSystemwith additionalCustomerEarth(TNSTT):asystem ofsupply where the Distribution Company provides anEarthconnectiontotheCustomersMainEarth Terminal and a local Earth provided by the Customer is also connected to the same MET, having an Earth Resistance value ofnot more than 10 Ohms.2.1.28Earthing or Earthed: a general term used to describe the connection ofmetallic parts ofan Electrical Installation or an Appliance to Earth.[Note: the terms Grounding or Grounded are sometimes used outside these Regulations to mean the same as the above.]The Electricity Wiring Regulations 2007 (Revision 1) 2022.1.29EarthConductor:aconductorusedtoconnectExposed-Metallic-Partsof anElectricalInstallationandassociated AppliancestoEarth,andprovidingameansforthesafe passage ofearth fault current.This includes the following defned terms:(a)MainEarthConductor(MEC):conductors connectedbetweenDistributionBoards,Earth Electrodes and Main Earth Terminals; and(b)CircuitEarthConductor(CEC):conductors connectedfromFinalDistributionBoardsand associatedwithFinalCircuits,includingAppliance EarthConductorssuchaswithinafexiblecord. OutsidetheseRegulationsthesemayalsobeknown astheCircuitProtectiveConductor(CPC)orEarth Continuity Conductor (ECC).2.1.30EarthElectrode:aconductororgroupof conductors inintimatecontactwithEarth,providinganelectrical connectiontoEarth,andnormallyhavingaknownand measurable value ofEarth Resistance (may also be known outsidetheseRegulationsasEarthRod,orGrounding Rod).2.1.31EarthedEquipotentialBonding(EEB):theconnection of Extraneous-Metallic-PartswithinaPremisesusing designatedconductorssuchthatpotentialTouchVoltages arekepttoasafevalueduringthepassageof earthfault current(alsoknownoutsidetheseRegulationsasPME Bonding).This defnition includes the following:(a)MainEquipotentialBonding:theconnection of majorExtraneous-Metallic-Parts,suchaspipe services and metallic structures, at their point ofentry intoaPremisestotheMainEarthTerminalinan Installation, using designated conductors; andThe Electricity Wiring Regulations 2007 (Revision 1) 212 Defnitions(b)SupplementaryEquipotentialBonding:the connectionof Extraneous-Metallic-Partswitheach other or with Exposed-Metallic-Parts within an area wheresuchpartsaresimultaneouslyaccessibleto persons, such that the potential Touch Voltage during an earth fault is kept to safe limits.[Note:fordisconnectiontimesgreaterthan0.4seconds asafeTouchVoltagelimitmaybetakenas50 Vfordry conditions and 25 V for wet conditions.]2.1.32Earthed Equipotential Bonded System (EEBS): a system whereprotectionagainstelectricshockduetoIndirect Contact is achieved by the provision ofEarthed Equipotential Bonding conductors, in association with Protective Devices for the automatic disconnection ofsupply.2.1.33EarthLeakageProtection(ELP):theprovisionofprotection against electric shock due to Indirect Contact by theuseof RCDsorothersensitiveearthfaultprotective deviceswhichautomaticallydisconnectthesupply suffciently quickly so as to prevent danger to persons.2.1.34EarthLeakageProtectedSystem(ELPS):asystemofsupplywhereEarthLeakageProtectionisprovidedon Final Circuits and back-up ELP is provided at the Supply Intake.2.1.35EarthResistance:theresistance(inOhms)fromany point on an Installation to Earth, being measured using an approved testing device and approved procedure.2.1.36EarthFaultLoopImpedance(Zs):thetotalimpedance presentedtoanearthfaultcurrent,comprisingthe impedance ofthe following parts ofa system, illustrated in Appendix A5(g):(a)the Circuit Earth Conductor;(b)the Main Earth Terminal;The Electricity Wiring Regulations 2007 (Revision 1) 222(c)themainEarthConductorsconnectingtoEarth Electrodes or the Distribution Company Earth;(d)the path ofearth fault current through the general mass ofEarth, or through the earth sheath or armouring ofthe Distribution Company cable;(e)theneutralearthconnectionattheDistribution Company transformer;(f)the distribution transformer winding; and(g)the phase conductor ofthe Circuit back to the point offault.2.1.37EarthLeakageCircuit-Breaker(ELCB):seeResidual Current Device.[Note:thetermELCBiscommonlyusedinterchangeablywith the term RCD.] 2.1.38Electrical Installation (abbrv: Installation): an Electrical Installationcomprisesanyfxedortemporarycable, switchgear,transformerorotherelectricalequipmentor apparatus within a Premises or other place where there is anelectricitysupply(includingoutdoorlocations).Fixed orportableelectricalAppliancesarenotconsideredpart of theElectricalInstallation,althoughtheseRegulations do include requirements for the connection ofAppliances (e.g. plugs and socket-outlets).2.1.39Electrical Installation Certifcate: a certifcate in the format indicated in these Regulations which is issued by a Licensed Contractor after completion ofwork on an Installation and provided to the Customer or Owner ofthe Premises.2.1.40Exposed-Metallic-Part:ametallicpartof anInstallation or Appliance which can be touched by persons and which isnotnormallylivebutmaybecomeliveduetoafault condition.Exposed-Metallic-Partsarerequiredtobe connected to Earth, see Regulation6.6.The Electricity Wiring Regulations 2007 (Revision 1) 232 Defnitions2.1.41Extraneous-Metallic-Part:ametallicpart,structureor any metalwork within a Premises which is not part of, and isunrelatedto,theelectricalInstallationandwhichisnot designedtocarrycurrent,butwhichmaybecomelive duetoafaultcondition.Extraneous-Metallic-Partsare required to be connected to Earth for Installations or parts ofInstallations classifed as Earthed Equipotential Bonded Systems, see Regulation5.5.2.1.42Extra-Low Voltage (ELV):see Voltage.2.1.43Final Circuit: see Circuit.2.1.44FunctionalEarth:anEarthorEarthingsystemwhichis providedforspecialfunctions(suchasreductionof radio frequencyinterference,noiseflteringforcomputers,etc) and which is separate from other Earth Conductors in an Installation but is connected to the Main Earth Terminal.2.1.45High Voltage: see Voltage.2.1.46IndirectContact:contactof apersonwithelectricity throughExposed-Metallic-Partsof anInstallationor Appliance,orthroughExtraneous-Metallic-Partsina Premiseswhichhavebecomeliveduringfaultconditions, see Guidance Note G4(b).2.1.47Installation: see Electrical Installation.2.1.48Law: means Law No (2) of1998 Concerning the Regulation of theWater,WastewaterandElectricitySectorinthe Emirateof AbuDhabi(asamendedbyLawNo(19)of2007).2.1.49Licensed Contractor: a company which has been assessed bytheDistributionCompanyascompetenttoworkon Electrical Installations and issued a Competency Licence.The Electricity Wiring Regulations 2007 (Revision 1) 2422.1.50Low Voltage: see Voltage.2.1.51Luminaire:equipmentwhichisdesignedtohouseone ormoreelectriclampsandwhichmayincludediffusers, fxtures, transformers and auxiliary Circuits but is taken to exclude the lamps themselves. Outside ofthese Regulations aLuminairemaycommonlybereferredtoasalight ftting.2.1.52Main Distribution Board: see Distribution Board.2.1.52Main Earth Terminal (MET): the main connection point atwhichthenominalvalueof EarthResistanceforan installation is taken, and to which Earth Conductors from EarthElectrodesortheDistributionCompanyEarthare connected.This will normally be at or close to the Customer Connection Point. The Main Earth Terminal may also be known as the main earth bar.2.1.54Owner: the legal owner ofa building or property in which anElectricalInstallationisinstalledandconnectedtoa supply ofelectricity.[Note: in some cases an Owner may also be a Customer.]2.1.55Premises:anyoccupiedorunoccupiedbuildingor enclosure or other place where there is an electricity supply. Such locations would include, but are not limited to, domestic premises, commercial premises, industrial premises, public buildings,parks,farms,temporarysupplies,construction sites,weddingtents,outbuildings,caravans,streetlighting and traffc signs. 2.1.56Prospective Fault Current: the value ofcurrent that would fowduetoashort-circuitfaultof negligibleimpedance between live phase conductors, or between phase conductors andEarth,alsoknownasfaultlevel.Themaximum ProspectiveFaultCurrentforaninstallationisnormally taken at the Customer Connection Point. The Electricity Wiring Regulations 2007 (Revision 1) 252 Defnitions2.1.57Protective Conductor:see Earth Conductor.2.1.58Protective Device: a device installed at the start ofa Circuit which will automatically disconnect the input ofelectricity in the event ofa fault or overload occurring on that Circuit. Such devices include, but are not limited to, fuses, fuse links, miniaturecircuit-breakers(MCB),mouldedcasecircuit-breakers(MCCB),earthleakagecircuit-breakers(ELCB), and residual current devices (RCD).2.1.59Radial Circuit: see Circuit.2.1.60Residual Current Device (RCD): a Protective Device which isinstalledtoautomaticallyisolatethesupplytoaCircuit or Distribution Board when the vector sum ofcurrents in thephaseandneutralconductorsreachesapresetvalue (referredtoastheresidualoperatingcurrentorresidual current rating).2.1.61Ring Circuit: see Circuit.2.1.62Sub Distribution Board: see Distribution Board. 2.1.63SupplyIntake:atermusedtodescribethelocationor room housing the main cable and equipment provided by a Distribution Company to provision a supply ofelectricity to a Premises (includes the Customer Connection Point).2.1.64Spur Circuit: see Circuit.2.1.65TouchVoltage:theVoltagethatwouldappearduringan earthfaultconditionbetweenExposed-Metallic-Parts andExtraneous-Metallic-Partswhicharesimultaneously accessible to persons.[Note:thistermisusedonlyinconnectionwithprotection againstIndirectContactandisnotusedtorefertoDirect Contactwithelectricity.TheseriousnessofimpactofTouch Voltageonapersonwilldependonthebodyresistance andtheimmediatesurroundings,inparticularthe presenceofwater.SeeGuidanceNoteG4(h)andG5(b).] The Electricity Wiring Regulations 2007 (Revision 1) 2622.1.66Voltage: (a)HighVoltage(HV):ana.c.voltagegreater thanLowVoltageandlessthan36 kVbetween phasesor21 kVbetweenanyphaseandEarth (internationally referred to as Medium Voltage);(b)LowVoltage(LV):ana.c.voltagebelow 1000 Vbetweenphases,orbelow600 Vbetween anyphaseandEarthor,ad.c.voltagebelow 1500 Vbetweenconductors,orbelow900 V between any conductor and Earth;(c)Extra-Low Voltage (ELV): a voltage not exceeding 50 Va.c.or120 Vd.c.whetherbetweenlive conductors or between live conductors and Earth;(d)Separated Extra-Low Voltage (SELV): an Extra-lowVoltagesystemwhichiselectricallyseparated from Earth in such a way that a single fault cannot give rise to the risk ofelectric shock;(e)ProtectiveExtra-LowVoltage(PELV):asystem whichhasthesamefeaturesasSELVexceptthat connectionof Exposed-Metallic-PartstoEarthis allowed; and(f)Reduced Low Voltage (RLV): a voltage which does not exceed 55 V a.c. between phase and Earth or 110 V a.c.between phases.The Electricity Wiring Regulations 2007 (Revision 1) 2733.1Technical standards, materials and workmanship3.1.1TheseRegulationsprovideguidelinesandtechnical standards which are consistent with the principles contained in BS 7671:2001 (also known as the IEE Wiring Regulations 16thEdition).WhereanyprovisionintheseRegulations contradictsanyprovisioninBS 7671,therequirements, standardsorspecifcationsundertheseRegulationsshall apply.[Note:theseRegulationsareinsomeaspectsmoreprescriptive thanBS 7671,andtakeaccountofthephysicalenvironmentof AbuDhabiEmirate,aswellasthetypicalskillsandlanguage diversity in the region.]3.1.2Where a provision or technical requirement is not covered by these Regulations, BS 7671 may be used as a guideline or specifcation, with prior approval from the Distribution Company and the Bureau.3.1.3All materials used in Electrical Installations shall be ofgood quality and installed in a neat and orderly manner.3.1.4Allmaterialsandequipmentshallcomplywithrelevant internationalstandardswhichshallbemainlyBS(British Standards)orIEC(InternationalElectrotechnical Commission) standards, as referenced in these Regulations. Otherinternationalstandardsmaybeused,inparticular where none are specifed in these Regulations, with the prior approvalof theDistributionCompanyandtheBureau. A list ofBS and IEC standards applying to the main types ofequipment is given in Appendix A3.3.1.5TheDistributionCompanymayissuespecifcationsand requirementsinadditiontotheseRegulations,whichwill beendorsedorapprovedbytheBureau,andprovidedto interested parties on request. General principles and safety requirementsThe Electricity Wiring Regulations 2007 (Revision 1) 2833.1.6Referencemustbemade,whererelevant,toUAEor Gulfstandards which may be issued from time to time by theEmiratesStandardisationandMetrologyAuthority (ESMA).3.2Approval ofinstallations3.2.1AnyCustomerrequiringanewsupplyoralterationtoan existing supply must make an application to the Distribution Companyusingtheappropriateformsandprocedure published by the Company. 3.2.2Theproposeddesignof anInstallationmustbeapproved bytheDistributionCompanybeforecommencement of construction.Detailsof theproposeddesignmustbe submitted,togetherwithappropriatecalculationsand wiringdiagrams,usingthestandardsymbolsshownin Appendix A11.3.2.3NewInstallationsmustbeinspectedandtestedbythe Distribution Company in accordance with the requirements of Chapter8of theseRegulations,priortoprovidingan electricity supply.3.2.4TheDistributionCompanymay,whereappropriate,seek evidenceof complianceagainstrelevantstandardsofequipment and components used in the Installation.3.2.5The Customer must provide an estimate ofthe Connected Load at the Premises, including at each Distribution Board. Inaddition,theDiversifedLoadforthewholePremises and at each Distribution Board, must be calculated by the Customers appointed Licensed Contractor, design engineer or other qualifed person and submitted in the format given in Appendix A20(e), see Guidance Note G2. The Electricity Wiring Regulations 2007 (Revision 1) 293 Principles3.3Extensions, alterations and repairs3.3.1NoextensionoralterationtoanElectricalInstallation may be made without prior notifcation to the Distribution Company or without approval, testing and certifcation in accordance with Regulation3.2.3.3.2All extensions or alterations to an existing Installation must comply with the requirements ofthese Regulations.3.3.3Not withstanding clause 3.3.1 and3.3.2,repairs to existing installationsmaybemadeusingstandardsof equipment compliant with the old installation, but limited to work ofanessentialnatureonalike-for-likebasis.Workonany part ofthe Installation other than Final Circuits, including any Distribution Board and any items at the Supply Intake, must be notifed to the Distribution Company.3.3.4Anyproposedincreasegreaterthan10%of thetotal ConnectedLoadataPremises,orgreaterthan10%oftheConnectedLoadatanyDistributionBoard,mustbe approved by the Distribution Company.3.4Licensed contractors3.4.1Work on Electrical Installations may only be carried out by Licensed Contractors who have been assessed and approved bytheDistributionCompanyandissuedaCompetency Licence.3.4.2The process for approval ofLicensed Contractors shall be publishedbytheDistributionCompanyandapprovedby the Bureau.3.4.3A register ofLicensed Contractors shall be kept up-to-date bytheDistributionCompanyandprovidedonrequestto any person.The Electricity Wiring Regulations 2007 (Revision 1) 3033.5Requirements for safety3.5.1The provisions ofthese Regulations require that all Electrical Installationsaredesignedandconstructedsoastoensure thesafetyof allpersonswhomayoperate,maintainor otherwise use or be affected by any part ofan Installation. In addition to the requirements detailed under the relevant sectionsof theseRegulations,thefollowinggeneralsafety principles shall apply.[Note: these Regulations do not include detailed requirements for the maintenance of Installations. However, the maintainability of Installations must be adequately catered for in their design and construction.In addition the requirements for periodic inspection and testing, as detailed in Chapter8, may give rise to the need for maintenance and repair work.]3.5.2All parts ofan Electrical Installation shall be designed and constructed so as to prevent Danger.3.5.3Allpartsof anElectricalInstallationshallbesuffciently sizedandratedtosafelycarryoutthefunctionforwhich they are required.3.5.4Allpartsof anElectricalInstallationshallbeinsulated appropriatetothefunctiontheyserve,inconsideration of theexpectedoperatingenvironment,soastoprevent Danger, see Regulation5.7.3.5.5AllExposed-Metallic-Partsof anInstallationandofAppliancesmustbeconnectedtoEarthviaappropriate EarthConductors,soastoprotectagainstelectricshock, see Regulation 6.6.3.5.6Except in specifed circumstances, all Electrical Installations shallbeprovidedwithEarthLeakageProtectionat thesourceof supply,atallFinalCircuitsandatother appropriatepoints,seeRegulation 5.3.4.WhereEarth LeakageProtectionisnotprovidedtherequirements forEarthedEquipotentialBondingshallapply,see Regulation5.5.The Electricity Wiring Regulations 2007 (Revision 1) 313 Principles3.5.7AllElectricalInstallationsmustbeprotectedagainst damage caused by excess current due to a fault or overload by suitable Protective Devices, see Regulation5.2. 3.5.8All Electrical Installations must be provided with a means of isolatingtheelectricitysupplyatsuitablesections, subsectionsandCircuits,andatpointswhereAppliances are used, see Regulation5.6. 3.5.9All parts ofan Electrical Installation must be suitably located soastoprovidesafeaccessforoperation,maintenance andrepairandmustbeprotectedagainstaccidentalor deliberate interference or damage.3.5.10ElectricalInstallationsmustbedesignedandconstructed with particular consideration given to the risk offre due to electricalfaultsandthepropagationof frethroughparts ofthe Installation. See clauses 6.1.1(c), 7.2.4, 7.4.5, 7.4.15, 7.5.3, 7.5.4, 8.1.4(g) and 10.3.2.3.5.11AllElectricalInstallationsmustbeinspectedandtested at the time offrst commissioning and at regular intervals thereaftertoensureongoingsafety,asdetailedunder Chapter 8 ofthese Regulations.3.5.12Additionalrequirementsforsafetyinspeciallocationsare covered in Chapter9.3.6Labelling and identifcation3.6.1All Electrical Installations must be suitably labelled so as to giveinformationontheelectricitysupplyparameters,the source ofsupply, location in relation to other Installations, and any special precautions to be taken.[Note:suchinformationwouldnormallybeprovidedat theSupplyIntakeroom;specialprecautionswouldinclude information on other sources of supply such as local generation or interconnection with other Premises.]The Electricity Wiring Regulations 2007 (Revision 1) 3233.6.2The means ofisolation ofthe main source ofsupply must be clearly labelled and accessible to authorised persons, see Regulation5.6.3.6.3Theprovisionof EarthLeakageProtection(asrequired underRegulation 5.3.4)mustbeclearlyindicatedat appropriate isolation points, including a notice informing Customers ofthe need for regular testing ofRCD devices, see Appendix A12(c).3.6.4IndividualCircuits(includingneutralandEarth Conductors) must be identifed by numbering at the source endand,whereappropriate,atintervalsalongtheroute, see Guidance Note G7(f).3.6.5Fornon-domesticInstallations,allaccessoriesandfttings must be marked with Circuit identifcation numbers.[Note:Circuitidentifcationnumbersmustindicatethe DistributionBoardfromwhichanAccessoryorfttingis supplied,andmaybefxedexternallyorinternally,i.e.either outside or inside cover plates.]3.6.6Load distribution schedules, as shown in Appendix A20(e), must be provided at each Distribution Board.An overall wiring diagram showing the location and interconnection of DistributionBoardsmustbeprovidedattheSupply Intake.3.6.7Where parts ofan Installation are accessible or visible to thegeneralpublictheymustbelabelledwithawarning: LIVE 230/400 VOLTS DANGER OF DEATH or similar wording.This warning must be written in English andArabic,seeexampleinAppendixA12(a).However, parts offnal Circuits and other points ofnormal use may be excluded from this requirement.The Electricity Wiring Regulations 2007 (Revision 1) 333 Principles3.7Environmental conditions3.7.1Allpartsof anElectricalInstallationmustbesuitably designed,constructedandmaintainedsoastooperate safely and carry out their designed function in the expected operatingenvironment.Thefollowingenvironmental conditions may be used as a guide ifno other special factors apply: (a)maximum ground temperature (at 1 m depth): 35C;(b)soil resistivity: according to local conditions;(c)weather:mainlysunny,occasionalfog(causing condensationonoutdoorequipment),andoccasional sandstorms;(d)air quality: frequently dusty;(e)maximum humidity: 100%; (f)maximum ambient (air) temperatures:outdoor (shaded): 50Coutdoor(unshaded):temperatureriseduetosolar gain must be calculated for the relevant equipment or the maximum black bulb temperature may be used (typically 10 C above ambient temperature)indoor (not air conditioned): 40Cindoor (air conditioned): 30C[Note:insomesituationstheambienttemperatureforindoor non-air-conditionedsituationsmayreachtheoutdoorshaded temperaturee.g.asmallprefabricatedbuildingwithlittle ventilation, or a garage which is open to the atmosphere.]The Electricity Wiring Regulations 2007 (Revision 1) 343The Electricity Wiring Regulations 2007 (Revision 1) 3544.1Electricity supply parameters4.1.1Theparametersforelectricitysuppliesprovidedto Customers in the Emirate ofAbu Dhabi are defned in the Electricity Supply Regulations 2007, issued by the Bureau. These are repeated below.Declared voltage and frequency4.1.2ThedeclaredsupplyvoltageprovidedtoCustomers connectedatLVshallbe230 Vsingle-phaseor400 V three-phase.[Note:thisisachangetotheprevioussupplyvoltagedeclared byDistributionCompaniesof240/415 V.SeeGuidance Note G1.]4.1.3The permissible variation ofthe supply voltage shall be kept within + 10% and - 6% ofthe declared supply voltage.4.1.4The declared supply frequency provided to Customers shall be 50 Hz.4.1.5Thepermissiblevariationof supplyfrequencyshallbe +/-0.1% (i.e. +/- 0.05 Hz).4.1.6For Customers supplied at voltages above LV the permitted variationof supplyvoltageshallbe+/- 10%andthe permitted variation offrequency shall be +/- 0.1%.Harmonics, voltage disturbances and power factor4.1.7Customers Installations, and the use ofelectrical equipment therein,mustbedesignedtoavoidthegenerationofdisturbancesintheelectricitysupply.Thesemayinclude voltagefuctuations,voltagedips,voltageunbalanceand harmonics, which are ofa magnitude that adversely affect other Customers.Electricity supply intake andsupply parametersThe Electricity Wiring Regulations 2007 (Revision 1) 3644.1.8The permitted limits ofsuch disturbances are given in the ElectricityDistributionCode,Annex1.Customerswill be required to install flters or other equipment to mitigate againstsuchdisturbancesthatareoutsidethepermitted limits (as explained in the Electricity Distribution Code).4.1.9ThepowerfactorattheConnectionPointbetweenthe DistributionCompanyandtheCustomersInstallation must be maintained at 0.9 lagging or higher.Power factor correctionequipmentmustbeusedwhererequiredto achieve this value, see Chapter 10.Prospective fault current4.1.10The maximum three-phase Prospective Fault Current (fault level)forLVsuppliesshallbe46 kA(1second)attheLV busbar ofthe Distribution Companys HV/LV substation, or30 kA(1second)ataLVfeederpillar,or25 kA (1 second) at a LV service turret. 4.1.11The maximum 3-phase Prospective Fault Current for HV supplies shall be 31.5 kA (for 3 seconds) or such lower value asotherwiseagreedbetweentheDistributionCompany and the Customer.4.2Electricity supply intake4.2.1TheelectricitySupplyIntakemustbepositionedina dedicated room or housing.4.2.2Otherthaninexceptionalcircumstances,andwithprior approvalfromtheDistributionCompany,thereshallbe only one electricity Supply Intake for any Premises.4.2.3The Supply Intake must be positioned in an area which is readily accessible to Distribution Company staffand other authorised persons, particularly in an emergency, and must be at or close to the outside perimeter ofa Premises.The Electricity Wiring Regulations 2007 (Revision 1) 374 Supply Intake4.2.4TheSupplyIntakemustnotbepositionedinanarea controlledbyoneof thetenantsinamulti-occupancy building.4.2.5Equipment at the electricity Supply Intake must be located in a safe and accessible position, and kept clear ofhindrance at all times.4.2.6The use ofSupply Intake rooms as storage rooms for any tools, equipment or other materials is prohibited.4.2.7The Supply Intake must not be located on the reverse side of abathroomorkitchenwall,orbelowabathroomor kitchen.The Supply Intake must not be located below any water services or pipes, such as mains water supply, storage tanks, air conditioning chillers, or other liquids or hazardous materials.4.2.8The Supply Intake room must be well ventilated, preferably withouttheneedforforcedaircirculation.Whereair conditioningisrequiredintheSupplyIntakeroomthe requirement for fresh air circulation must also be provided to avoid condensation.4.2.9Atleastoneemergencylightingunitmustbefttedinall Supply Intake rooms, which must be provided with a battery ratedforminimum2hoursillumination,andsubjectto adequate routine maintenance.4.2.10DoorstoSupplyIntakeroomsmustbearrangedtoopen outwards, be kept free from obstructions, and be capable ofbeing opened from the inside without the use ofa key.4.2.11Theneedfordeliveryof heavyequipmenttotheSupply Intakeroomduringconstructionandforfuturerepairor alterations must be taken into account in the location ofthe Supply Intake room.The Electricity Wiring Regulations 2007 (Revision 1) 3844.2.12For Supply Intake rooms ofgreater than 6 m in length more than one door shall be provided as a means ofemergency access.4.2.13Installationlayoutsandminimumsizesof theelectricity Supply Intake are given in Appendix A12(b) and A12(d).4.2.14For large Installations the Supply Intake may consist ofone or more LV switchboards, the requirements for which are given in Regulation7.9.4.2.15WhereaHV/LVsubstationisrequiredforthesupplyofPremises,thedesignandconstructionrequirementsforthe substation will be specifed by the Distribution Company.4.3The customer connection point4.3.1Exceptwhereanalternativedefnitionof theCustomer ConnectionPoint(CCP)hasbeenagreedbetweenthe CustomerandtheDistributionCompany,theCCPis deemedtobeattheincomingcableconnectionfromthe Distribution Company. This is most commonly at the Main DistributionBoardandbeforethemaincircuit-breaker. Metering equipment may be connected through a current transformeratapositionremotefromtheCustomer Connection Point.4.3.2EquipmentattheCustomerConnectionPointmustbe lockedorsealedbytheDistributionCompanytoprevent deliberateoraccidentalinterference.Suchlocksorseals will include those for metering equipment, etc.4.3.3TheCustomerConnectionPointmustalwaysinclude ameansof emergencyisolationinthecaseof afaultor breakdown(e.g.maincircuit-breaker)whichisreadily accessibleandclearlylabelledsoastobeeasilyoperated bytheCustomer.Suchmeansof emergencyisolation mustbeleftunlockedatalltimes,exceptwhenlockedin The Electricity Wiring Regulations 2007 (Revision 1) 394 Supply Intakethe open position to allow access to the Installation (e.g. for maintenance).4.4Multiple occupancy premises4.4.1MultipleoccupancyPremisesmaybesuppliedbyrising and lateral mains (cabling or busbars) which are connected directlytotheSupplyIntakefromtheDistribution Company.Risingandlateralmainswillnormallybe owned and operated bythe building Owner onbehalfofall Customers in a Premises. 4.4.2TheelectricitymeteringforindividualCustomersfora rising or lateral mains system will normally be at the point nearesttoeachCustomer,remotefromthemainSupply Intake.4.5Metering requirements4.5.1TherequirementsforCustomermeteringarecontained in the Customer Metering Regulations 2005, issued by the Bureau.Additional detailed requirements and procedures willbeprovidedbytheDistributionCompanywhere required.The Electricity Wiring Regulations 2007 (Revision 1) 404The Electricity Wiring Regulations 2007 (Revision 1) 4155.1General principles5.1.1All Electrical Installations must be designed, constructed and maintained to provide protection against the following:(a)overload;(b)short-circuits (phase to phase or phase to Earth); and(c)electric shock (due to Direct or Indirect Contact with electricity).5.1.2Protection against conditions ofoverload and short-circuit willnormallybeprovidedbyMCBs,MCCBsorsimilar devices, see Regulation 5.2 below.5.1.3Protectionof personsagainstelectricshockduetoDirect Contact or Indirect Contact must be provided by one ofthe methods detailed in Regulation 5.3 below.[Note:seeGuidanceNoteG4(a)andG4(b)forexplanationof Direct andIndirect Contact.]5.2Overload and short-circuit protection5.2.1AllElectricalInstallationsmustbeprovidedwithdevices thatprotectagainstthermal,electromagneticandother detrimentaleffectscausedbyoverloadandshort-circuits. Suchdevicesmustbelocatedatsuitablesectionsand Circuitssoastogiveeffectiveautomaticdisconnectionin such conditions.5.2.2Themaincircuit-breakerattheCustomerConnection Pointmustbeof MCBorMCCBtypeandadequately rated for the maximum Prospective Fault Current.Fused cutoutsmustnotbeusedexceptinspecialcircumstances approved by the Distribution Company (e.g. street lighting supplies).ProtectionThe Electricity Wiring Regulations 2007 (Revision 1) 4255.2.3All Circuits must be individually protected against overloads andshort-circuitsbysuitabledevices.Replaceableor re-wireablefuselinksarenotpermittedforthispurpose (exceptinthecaseof capacitorbanks,seeRegulation 10.2).5.2.4The time-current performance characteristics ofProtective Devicesmustconformtotherelevantreferencestandards listed in Appendix A3.[Note: the time-current performance curves for MCBs are shown in Appendix A6(a) (d).]5.2.5Toensureprotectionagainstoverload,Circuitconductors mustbesizedtakingintoaccountthetime-current characteristic ofthe Protective Device.[Note: in order to provide adequate protection against overload the Protective Device nominal rating must be not more than the maximum rating of the Circuit for which overload protection is required, see Appendix A6(f).]5.2.6ProtectiveDevicesattheMainDistributionBoardmust haveamaximumProspectiveFaultCurrentratingabove that declared by the Distribution Company for the relevant Customer Connection Point.5.2.7ProtectiveDevicesdownstreamof theMainDistribution Board may have a reduced Prospective Fault Current rating, takingintoaccounttheenergylet-throughcharacteristic (I2t) ofthe upstream Protective Device, see Appendix A6(e). Where appropriate, an allowance may also be made for the attenuation ofProspective Fault Current due to the Circuit impedance.The Electricity Wiring Regulations 2007 (Revision 1) 435 Protection5.3Electric shock protectionDirect contact5.3.1Protection ofpersons against the risk ofDirect Contact with electricity must be provided by either physically preventing contact or by an inherently safe systems ofsupply, using one or more ofthe following measures:(a)insulated conductors, see Regulation5.7;(b)secure enclosures, barriers or covers on live parts;(c)Separate Extra-Low voltage (SELV) system; or(d)Protective Extra-Low Voltage (PELV) system.[Note: SELV conductors at voltages of 12 V a.c. or 30 V d.c. may beun-insulatedbutmustbeprovidedwithoverloadandshort circuit protection.]5.3.2Residual Current Devices with a residual current rating of30 mA and complying with BS EN 61008 and BS 4293 may beusedasameansof supplementaryprotectionagainst DirectContact.However,RCDsmaynotbeusedasthe solemeansof protectionagainstDirectContacti.e.one ofitems (a) to (d) above must be used in addition to RCD protection.[Note: RCD devices with a residual current rating above 30 mA are not considered to provide adequate protection against Direct ContactbutmaybeusedtoprovideprotectionagainstIndirect Contact see Regulation5.4. It should be noted that RCD devices do not protect against electric shock between phase conductors or between phase conductors and neutral.] The Electricity Wiring Regulations 2007 (Revision 1) 445Indirect Contact5.3.3Indirect Contact with electricity can occur when a voltage appearsonEarthedpartsof anInstallationorAppliance due to the passage ofearth fault current and whilst a person is in contact with either:(a)anExposed-Metallic-PartandanExtraneous-Metallic-Part; or(b)an Exposed-Metallic-Part and Earth; or(c)an Extraneous-Metallic-Part and Earth.5.3.4Protectionagainsttheriskof electricshockintheabove cases must be provided by either:(a)anEarthLeakageProtectedSystem,whereRCDs or similar devices are provided at Final Circuits and back-up RCDs or other sensitive earth fault protection is provided at the Supply Intake, see Regulation5.4; or(b)in parts ofPremises where Earth Leakage Protection isnotprovided,orotherspecifedcircumstances, anEarthedEquipotentialBondedSystem,see Regulation5.5.5.3.5Not withstanding clause5.3.4(b) the requirement for Earth Leakage Protection on all Final Circuits where Appliances maybeusedbyanypersonismadecompulsorybythese Regulations. 5.4Earth leakage protected systems5.4.1AnEarthLeakageProtectedSystem(ELPS)isdefnedas one where protection against Indirect Contact is provided bytheuseof RCDsorothersensitiveearthfaultdevices onallFinalCircuitsandback-upELPisprovidedatthe Supply Intake.Such a system is required to automatically disconnectthesupplyataFinalCircuitorattheSupply Intake suffciently quickly so as to prevent Danger. The Electricity Wiring Regulations 2007 (Revision 1) 455 Protection5.4.2ForFinalCircuitsELPdevicesmustbeof theRCDtype wherebythe device will trip ifthe vector sum ofcurrents carriedbythephaseandneutralconductorsisabovea presetvalue,seeGuidanceNoteG5(c).Voltage-operated earth leakage devices (ELCB) are not permitted.[Note:modernRCDsaremagneticallyactuatedwhilstthe oldertypeofELCBdevicesoperatebydetectingfaultvoltage and require a connection between a Main Earth Conductor and anEarthElectrode;thesedevicesarethereforevulnerableto maloperation due to parallel earth paths.]5.4.3RCDdevicesforFinalCircuitsmusthaveatime-current performancecharacteristiccomplyingwithBSEN61008 and BS 4293. This requires that the device must operate within 200millisecondsatitsresidualcurrentratingandwithin 40 millisecondsat5timesitsresidualcurrentrating.It must not operate below 50% ofits residual current rating, see Guidance Note G5(a).5.4.4For Final Circuits which are liable to carry pulsating or d.c. currentsRCDdevicesmustbeof typeA(pulsatingd.c. sensitivity)andforRCDdevicesrequiringtime-delayed operationtypeSdevicesmustbeused,seeGuidance Note G5(d).5.4.5EarthLeakageProtectionprovidedattheSupplyIntake must be set to discriminate with ELP devices at Final Circuits (i.e.earthfaultsonFinalCircuitsmustbeautomatically disconnected by the closest ELP device, except in the case ofback-up operation ofdevices at the Supply Intake).See Appendix A5(m) and Guidance Note G4(e).[Note:suchdiscriminationmaybeprovidedbytime-delayed RCDs,earthfaultrelaysorothersuitabledevicesateachLV panel or circuit breaker at the Supply Intake.ELP is not required atSubDistributionBoardsbut,ifprovided,mustdiscriminate with ELP devices on upstream and downstream Circuits.]The Electricity Wiring Regulations 2007 (Revision 1) 4655.4.6The operating current setting for ELP devices at the Supply Intake must take into account the nature ofthe Installation (e.g.commercial,industrial,etc),thelikelihoodand magnitude ofearth fault currents, and the requirement for protectionagainstIndirectContact,seeAppendixA5(m) and Guidance Note G4(f).[Note:wheretheSupplyIntakeconsistsofamulti-panelLV switchboard, each panel or circuit breaker should be ftted with ELP devices in order to limit the extent of power interruptions. The ELP device for the incomer panel must discriminate with the outgoing panels / circuits.]5.4.7Earthed Equipotential Bonding is not required in an ELP system,althoughitmaybeprovidedassupplementary protectionagainstIndirectContact,seeGuidance Note G4(d).[Note:EarthLeakageProtectiondevicesprovideprotection againstelectricshockbylimitingthetimethatcurrentmay passthroughthebodyofapersontoEarth;theydonotlimit themagnitudeofcurrent,exceptbythefeatureofearlycut-off for a rising current.In addition, ELP devices provide protection againsthighresistanceearthfaultsthatmaypersistinan installation if the fault current is too low to operate overcurrent devicessuchasMCBs.Suchfaultsmaycauseoverheatingof Circuits or connections and lead to a fre.]5.4.8At each Distribution Board or other point where an RCD isprovidedasuitablelabelmustbeaffxedtoinformthe Customerof thecharacteristicsandmodeof operation of thedeviceandtheneedforroutinetesting,see Appendix A12(c).5.4.9FordomesticPremisestheresidualcurrentratingfor ELP devices must be 100 mA for Final Circuits supplying fxedequipment(e.g.lightingandairconditioning)and 30 mAforFinalCircuitswhereAppliancesmaybeused bypersons(e.g.allsocket-outlets,allkitchenAppliances, otherAppliancesaccessibletopersons),and30 mAfor allCircuitsinabathroom,seeRegulation 9.3.Afulllist The Electricity Wiring Regulations 2007 (Revision 1) 475 Protectionof applicationsandresidualcurrentratingsisprovidedin Appendix A5(m).5.4.10SpecialCircuitswithinaPremises,wheretherewouldbe signifcantdetrimentordangerfromthetrippingof the Earth Leakage Protection, may be excluded from the zone ofEarth Leakage Protection.Such instances may include Circuitssupplyingfreprotectionequipmentorsafety alarms(notsecurityalarms)orunoccupiedsites(suchas telecommunications stations, water pumping stations, etc). All such cases must be declared in the Electrical Installation CertifcateforthesiteandapprovedbytheDistribution Company.In these cases the requirements for an Earthed Equipotential Bonded System must be met for the relevant Circuits, see Regulation5.5.5.4.11Circuitswithhighearthleakagecurrents(e.g.electronic equipment or industrial machinery) may be provided with ELPdeviceswithhigherresidualcurrentratings,upto 500 mA.ThesemustbeclearlystatedontheElectrical Installation Certifcate.5.4.12Notwithstanding clauses5.4.10 and5.4.11, all Circuits from whichportableAppliancesmaybeused,oranyoutdoor equipmentaccessibletopersons,mustbeprovidedwith EarthLeakageProtectiondeviceswitharesidualcurrent rating no greater than 30 mA.5.4.13An earth leakage alarm may be provided for Circuits which areexcludedfromthezoneof EarthLeakageProtection (e.g. an alarm that does not cause tripping ofthe Circuit but gives an audible and visible warning to appropriate persons in the Premises). 5.5Earthed equipotential bonded systems5.5.1AnEarthedEquipotentialBondedSystem(EEBS)is defnedasonewhereprotectionagainstIndirectcontact isprovidedbytheinstallationof EarthedEquipotential The Electricity Wiring Regulations 2007 (Revision 1) 485Bonding such that voltage rises between Exposed-Metallic-Parts and Extraneous-Metallic-Parts are kept to a safe value for the duration ofan earth fault (i.e. the time it takes for the relevant Protective Device to trip).[Note:anEEBsystemreliesontheprinciplethatallExposed-Metallic-PartsandExtraneous-Metallic-Partswhichare accessible to persons are connected to the Main Earth Terminal andthereforetheprospectiveTouchVoltagebetweenthemis limitedtoavaluewhichissafewhentakingintoaccountthe operating time of the relevant Protective Device.In addition, it is assumed that a person cannot be in contact with Earth whilst touchinganyMetallicPartinaPremisesseeGuidanceNote G4(b) and G4(h).]5.5.2For an EEB system the operating characteristics ofProtective Devicesmustlimitthedurationof anyearthfaulttoless than0.4secondsforCircuitssupplyingApplianceswhich are accessible to people, and less than 5 seconds for all other parts ofthe Installation.5.5.3Themostcommonlyusedmethodforcheckingthe prospectivefaultdurationisbyreferencetodataon thelimitingvaluesof earthloopimpedanceforthe Protective Device concerned. For MCBs this is provided in Appendix A5(h), taken from BS 7671.5.5.4Main Equipotential Bonding Conductors must be installed from the Main Earth Terminal to connect metallic service pipes and other Extraneous-Metallic-Parts at points closest to the entry ofsuch parts to a Premises.5.5.5InhighriskareasSupplementaryEquipotentialBonding mustbeprovidedsothattheTouchVoltagebetween Exposed-Metallic-PartsandExtraneous-Metallic-Partsis kept to safe limits for the duration ofan earth fault.[Note:highriskareasmayincludebathrooms,kitchens, laboratories, garages, confned spaces or other locations where the normal resistance of the body is reduced or the consequence ofanelectricshockmayleadtoanotheraccident,suchasfall from a height.For disconnection times greater than 0.4 seconds The Electricity Wiring Regulations 2007 (Revision 1) 495 Protectionsafe Touch Voltage limits may be taken as 50 V for dry conditions and 25 V for wet conditions.]5.5.6Themethodforcalculationof TouchVoltagebetween Exposed-Conductive-Parts andExtraneous-Metallic-Parts is illustrated in Guidance Note G4(h).5.5.7Items requiring Equipotential Bonding may include metallic pipes (particularly those connected to underground services such as water supply), steel beams, water tanks, baths, sinks and washbasins, etc.An illustration oftypical Equipotential Bonding arrangements is given in Guidance Note G4(c). 5.5.8ItisnotnecessarytoprovideEquipotentialBondingfor standalone metallic items which:(a)do not pose any risk ofproviding a conductive path to Earth (are isolated from Earth); or(b)do not pose any risk ofproviding a conductive path to any other Earthed part ofthe Installation; or(c)do not pose any risk ofbecoming live as a result ofan electricalfaultintheInstallation(i.e.aresuffciently remote from any Circuit or Appliance); or(d)are out ofreach ofany person.[Note:suchitemsmayincludemetaldoors,windowframes, inaccessiblestructuralbeams,smallmetallicfxingssuchas screws and brackets, etc.]5.5.9WhereCircuitconductorsareinstalledclosetoorwithin itemsof metalwork(suchasmentionedinclause 5.5.7) consideration must be given to provide additional protection or double insulation ofsuch conductors.[Note:examplesincludesituationswherecablespassthrough walls containing steel frames, metal door frames, metallic foor grids, suspended ceilings, etc.]5.5.10The sizing ofEquipotential Bonding Conductors is given in Appendix A5(j).The Electricity Wiring Regulations 2007 (Revision 1) 5055.5.11Thepointof connectionof anEquipotentialBonding Conductor to any item must be labelled: SAFETY EARTH BONDINGDONOTREMOVE,asillustratedin Appendix A5(d).5.6Isolation and switching5.6.1All Electrical Installations must be provided with a means ofsafe isolation at the Supply Intake, which must be lockable or otherwise provided with a means ofpreventing interference (e.g.bytheremovalof operatinghandlesintothesafe custody ofa responsible person).Isolation for maintenance or other work may be provided by the Protective Device ifit is lockable (except for HV equipment).[Note: mechanical equipment should be provided with a means of isolation close to the equipment which can be locked and kept under the control of the person performing maintenance.]5.6.2AnInstallationmustbefurthersectionalisedbymeansofisolation at the origin ofeach Circuit,in order to provide ease ofaccess for safe working.5.6.3Eachsocket-outletorotherconnectionpointtoan Appliance or other electrical equipment must be provided with a switch as a means ofisolation.Such switches must be provided with a neon indicator where it is desirable to have a visual indication ofthe presence or absence ofpower (e.g. fridge, fre alarm, gas or smoke alarm, and water heater).5.6.4Emergencyswitching(e.g.push-buttonswitch)must beprovidedformovingmachinerywhichmayrequire immediatemanualdisconnectionfromthesupplyinthe caseof anaccidentorothersituationtoavoidDanger. Suchequipmentmayincludelargemotors,ventilation equipment,industrialmachinery,etc.Emergencypush switchesmustoperateonallphasesandneutralof the supply, must be clearly marked and must be located in an easily accessible position. The Electricity Wiring Regulations 2007 (Revision 1) 515 Protection5.6.5Emergency switches must be designed so that their operation retains the switch in the offposition until it is intentionally unlockedorreset.Thereleaseof theemergencyswitch mustnotautomaticallyrestarttherelatedApplianceor machinery.5.6.6Functionalswitchingdevicesrequiredforcontrolor operation ofequipment and not for safety reasons need not comply with the requirements ofclauses5.6.1 to5.6.5.5.6.7Semiconductordevicescannotbeusedasameansofisolation for safety.5.6.8Water heaters, air conditioning units, fan-coil units, motors and other similar items must be provided with double pole isolation (or 4 pole isolation for 3-phase items) to ensure safe access for the purpose ofmaintenance and repair.[Note:doublepoleisolationmaybeprovidedbyaplugand socket-outlet arrangement.]5.7Insulation5.7.1AllElectricalInstallationsmustbesuffcientlyinsulated toprotectagainstelectricshockfromDirectContactby any person (clause5.3.1). Such insulation must be capable of withstandingwearandtearduringnormaluseof the equipment. Supplementary insulation or double insulation may be used where additional robustness is required.5.7.2Theapplicationof paints,resins,varnishesandsimilar materialsisnotconsideredtosatisfytherequirementsofclause5.7.1 and additional insulation, barriers or obstacles are required to prevent Direct Contact by any person.[Note: an example may be a motor winding which is enamelled orresincoatedandthereforemustbeguardedagainstDirect Contact by persons.]The Electricity Wiring Regulations 2007 (Revision 1) 5255.7.3Live conductors are required to be inaccessible without the useof aspecialkeyortool,availableonlytoauthorised personsandonlyforthepurposeof testing,usingspecial equipment and procedures.5.7.4Uninsulatedequipmentmaybeusedatvoltagesnot exceeding 12 V a.c. or 30 V d.c. and only where supplied by a SELV source, see Regulation 9.1.5.7.5Theinsulationresistanceof Circuitconductorsmust bemeasuredaspartof thetestproceduresgivenin Chapter 8andmustbegreaterthanthevaluesgivenin Appendix A19(f).5.7.6WhereanInstallationissuppliedbyundergroundcables nospecialprovisionsarerequiredforprotectionagainst over-voltagesarisingfromatmosphericoriginorfrom switching.WhereanInstallationissuppliedbyoverhead linesadviceshouldbesoughtfromtheDistribution Companyortherequirementsof BS 7671Chapter44 may be used.The Electricity Wiring Regulations 2007 (Revision 1) 5366.1General principles6.1.1Earthing ofExposed-Metallic-Parts ofan Installation and ofAppliances in a Premises is required to serve the following functions ofsafety:(a)allowthepassageof faultcurrentintheeventof a live conductor touching an Exposed-Metallic-Part;(b)ensurethatthemagnitudeof faultcurrentis suffcienttooperateProtectiveDevices,including Earth Leakage Protection devices, within 0.4 seconds forFinalCircuitssupplyingApplianceswhichare accessible to any person and within 5 seconds for all other parts ofan Installation; and(c)ensure that, in association with Protective Devices, a high resistance fault to Earth does not persist so as to cause overheating or fre.6.1.2The necessary requirements to achieve the above functions ofsafety are detailed in the following sections.6.2Systems ofearthing6.2.1Customers must be provided with a supply operating under either ofthe following earthing systems:(a)CustomerEarthedSystem(TT):theCustomer provides a Main Earth Terminal for the Installation, whichisconnectedtoasuffcientnumberof local EarthElectrodestoprovideamaximumEarth ResistancemeasuredattheCustomersMainEarth Terminal ofno greater than 10 Ohms (referred to in BS 7671 as a TT system);(b)DistributionCompanyEarthedSystem(TN-S):the DistributionCompanyprovidesaconnectionto theCustomersMainEarthTerminal,usingthe distributionnetworkEarthingsystem,normallyvia thearmouringormetallicsheathof theincoming supply cable (referred to in BS 7671 as a TN-S system). EarthingThe Electricity Wiring Regulations 2007 (Revision 1) 546TheDistributionCompanysystemisearthedatthe distributiontransformer(11kV/400V)andseparate earth and neutral conductors are used throughout the distribution network; or(c)Distribution Company Earthed System with additional CustomerEarth(TN-S-TT):theDistribution Companyprovidesanearthconnectiontothe CustomersMainEarthTerminalandalocalEarth providedbytheCustomerisalsoconnectedtothe same MET, having an Earth Resistance value ofno greater than 10 Ohms.[Note:Thesetypesofearthingsystemsareillustratedin AppendixA5(a)A5(c).Earthresistancevaluesoflessthan 10 Ohms may be specifed by the designer for purposes such as Functional Earthing or for specialist installations such as petrol stations, telecommunications sites, etc.] 6.2.2ThepreferredearthingsystemtobeusedinAbuDhabi Emirate is TN-S-TT.However, either TN-S or TT systems maybeusedwhereagreedbetweentheDistribution Company and the Customer.The type ofearthing system must be stated on the Electrical Installation Certifcate and clearly labelled at the Main Distribution Board.6.2.3In all cases the neutral and Earth Conductors must be kept separate and not connected together at the MET or at any other point in the Customers Installation.6.3Main earth terminal6.3.1TheMainEarthTerminalmustbeprovidedclosetoor within the Main Distribution Board or other switchgear at the Supply Intake.6.3.2Ameansof removingtheconnectiontoEarth(suchas by a detachable metal link) must be provided at the Main EarthTerminaltofacilitatetestingof theearthingof the installation and the source ofsupply, see Appendix A5(e).The Electricity Wiring Regulations 2007 (Revision 1) 556 Earthing6.3.3TheEarthResistancemeasuredattheMETmustbe recordedontheInstallationCertifcateinaccordance withtheproceduresdescribedinChapter 8.Methods of measuringEarthResistanceareshownin Appendix A19(a).6.4Earth electrodes6.4.1EarthElectrodesmustbeprovidedatPremiseswhich aresuppliedbyaCustomerEarthedSystem(TT)ora DistributionCompanyEarthedSystemwithadditional Customer Earths (TN-S-TT).6.4.2For Premises consisting ofmore than one building, where either a TT or TN-S-TT system is used, Earth Electrodes must be provided at each building that is more than 30 m distance from the Supply Intake. 6.4.3Earth Electrodes will normally comprise of15 mm diameter steel-coredcopperrodsdriventoaminimumdepthof3 m.Thetopof eachEarthElectrodemustbehoused inside a 300 mm x 300 mm x 300 mm inspection pit which isclearlylabelledandaccessibleforroutinetesting,see Appendix A5(d).Alternative types ofEarth Electrodes may be used with prior approval ofthe Distribution Company (e.g.plateorwiremeshtype,orstructuralsteelworkina building).[Note: where it is proposed to use structural steel or reinforcing steelasanEarthElectrode,suitabletestingpointsmustbe provided.]6.4.4WheremorethanoneEarthElectrodeisrequiredto achieve the required Earth Resistance value thesemust be separated at a distance greater than their mutual resistance zone.[Note:aminimumseparationoftwicetheearthelectrode depthisconsideredtogiveadequateseparationofthemutual The Electricity Wiring Regulations 2007 (Revision 1) 566resistancezones.SeeBS 7430forfurtheradviceonspacingof Earth Electrodes.] 6.4.5The condition ofthe ground in which an Earth Electrode isplacedmustbetakenintoaccounttoensureitslong-term performance. In particular, potential corrosion effects andgroundmoisturecontentisof criticalimportance. Proprietary chemical or salt materials may be used around the Earth Electrode to maintain moisture content but these mustbestableandsustaintheirchemicalpropertiesover time.6.4.6Forsuppliesof 500 Aratingandabove,atleasttwo independent Earth Electrodes must be provided, regardless ofthe Resistance Value achieved for each Earth Electrode, andconnectedtothesameMainEarthTerminal,see Appendix A5(k).6.4.7Metallic service pipes (such as water, gas, etc) must not be used as Earth Electrodes.6.5Earth conductors6.5.1IntheseRegulationsthefollowingterminologyisusedto refer to Earth Conductors in an installation, see illustration in Appendix A5(f):(a)MainEarthConductors(MEC):conductors connectedbetweenDistributionBoards,Earth Electrodes and Main Earth Terminals; and(b)CircuitEarthConductors(CEC):conductors connectedfromFinalDistributionBoardsand associated with Final Circuits, including Appliance EarthConductorssuchaswithinafexiblecord. Outside these Regulations these may also be known as the Circuit Protective Conductor (CPC) or Earth Continuity Conductor (ECC).The Electricity Wiring Regulations 2007 (Revision 1) 576 Earthing6.5.2AllEarthConductorsmustbecoveredwithgreen/yellow PVC insulation and terminated with purpose made lugs or fxings.6.5.3WhereassociatedwithCircuits,allEarthConductors mustbelabelledattheirterminationpointswithCircuit identifcation numbers, see Guidance Note G7(f).6.5.4The connectionofEarth Conductorsto EarthElectrodes must be madeusing corrosion resistant clamps.6.5.5WhereEarthConductorsareburiedbelowgroundthey mustbemechanicallyprotected(e.g.inplasticormetal duct or pipe) and, where necessary, with additional tiles or plates laid above the duct or pipe, see Appendix A5(d) and Guidance Note G6.6.5.6The connection ofEarth Conductors to the Main Earthing Terminal must be made using purpose made lugs or other fxings and the connection must be clearly labelled as shown in Appendix A5(d).6.5.7All Circuits must have a Circuit Earth Conductor sized in accordance with Appendix A5(j).6.5.8CircuitEarthConductorsmust,wherepracticable,run alongside the associated phase and neutral conductors.[Note: this minimises the risk of a Circuit Earth Conductor being damaged or disconnected without any damage or fault indication being detected via the phase conductors.]6.5.9Formetalsheathedorarmouredcables,thesheathor armouringmaybeusedastheEarthConductorwhere itisratedtotheequivalentof theconductorsizesshown in Appendix A5(j).The metal sheath or armouringmust beterminatedbysuitablecableglandswithappropriate connectiontoanEarthCondutor,seeGuidance NoteG7(i).However,wheresuchcablesareinstalled undergroundaseparateEarthConductormustbelaid alongside the power cable.The Electricity Wiring Regulations 2007 (Revision 1) 5866.5.10Theuseof metalconduit,trunking,busbartrunkingor switchgearmetalenclosuresasEarthConductorsisnot permittedwithoutthepriorapprovalof theDistribution Company.Insuchcases,theprovisionof additional measures such as resistance measurements orsupplementary Earth Conductors will normally be required.[Note:metalconduit,althoughnottobeusedasanEarth Conductor, must nevertheless be effectively connectedto Earth sinceitcomprisesanExposed-Metallic-Part.SeeGuidance Note G7(j).]6.5.11Noswitches,isolatorsorcircuit-breakersmaybeinstalled in the electrical path ofany Earth Conductor. Removable linksmaybeinstalledtoallowtestingattheMainEarth Terminal.6.6Exposed-metallic-parts6.6.1AllExposed-Metallic-Partsof anInstallation,including Appliances,mustbeconnectedtoEarthviaEarth ConductorsinaccordancewiththerequirementsofRegulation6.5.6.6.2Exceptionstoclause 6.6.1mayincludeinternalpartsofequipment or Appliances which cannot be accessed without frst disconnecting the electricity supply.6.6.3Class I Appliances having Exposed-Metallic-Parts must be provided with a suitable connection point or plug & socket arrangementwhichincludesconnectiontotheCircuit EarthConductor.ClassIIAppliancesdonotrequirean Earthconnection,seeillustrationsinAppendixA18(a) and A18(b).6.6.4AllconnectionpointsinanInstallationmustincludean Earth Conductor for future use.[Note: an example would be a plastic light switch which does not requireaCircuitEarthConductorbutonemustbeprovidedin any case for future use see Guidance Note G7(d).]The Electricity Wiring Regulations 2007 (Revision 1) 596 Earthing6.6.5ItemswithinanInstallationwhereitismandatoryfora connection to be made to an Earth Conductor are listed in Appendix A5(l).6.6.6Therequirementforconnectionof Extraneous-Metalic- PartstoEarthConductorsdependsonthetypeofprotection system used in an Installation, as explained under Regulation 5.5.6.7Earth fault loop impedance6.7.1The Earth Fault Loop Impedance (Zs) is defned as the total impedance presented to an earth fault current, comprising the impedance ofthe following parts ofa system, illustrated in Appendix A5(g):(a)the Circuit Earth Conductor (including the Appliance Earth Conductor);(b)the Main Earth Terminal;(c)the main Earth Conductors connecting to local Earth Electrodes (TT system) or the Distribution Company Earth (TN-S system);(d)thepathof earthfaultcurrentthroughthegeneral massof Earth,orthroughtheearthsheathor armouring ofthe Distribution Company cable;(e)in the case ofa Customer Earthed System (TT system) theneutralearthconnectionattheDistribution Company transformer;(f)the distribution transformer winding; and(g)the phase conductors ofthe Circuit back to the point offault.6.7.2All Installations must be designed and tested such that the Earth Fault Loop Impedance at any point in the Installation is ofa suffcient value to operate Protective Devices within 0.4 seconds for Final Circuits supplying Appliances which The Electricity Wiring Regulations 2007 (Revision 1) 606areaccessibletoanypersonandwithin5secondsforall other parts ofan Installation.[Note:thisrequirementisimportantforpartsofInstallations where protection against Indirect Contact is provided by Earthed Equipotential Bonding rather than by Earth Leakage Protection, see Regulations 5.4 and 5.5.]6.7.3ThemaximumEarthFaultLoopImpedancevalues required to meet the disconnection times in clause 6.7.2 for MCB devices are given in Appendix A5(h).6.7.4ThemethodfortestingEarthFaultLoopImpedance (including the external earth fault loop impedance) is given in Appendix A19(b) and A19(c).6.8Lightning protection6.8.1Lightning protection systems and associated earth electrodes mustbeseparatefromtheelectricalInstallationearthing system.6.8.2Aminimumdistanceof 7 mmustbeprovidedbetween lightningprotectionearthelectrodesandtheInstallation Earth Electrodes.6.8.3Lightningprotectionsystemsmustbedesigned, constructedandmaintainedinaccordancewithBSEN 62305,exceptthatthelightningprotectionsystemisnot tobebondedtotheInstallationMainEarthTerminal. [Seeclause 5.7.6forrequirementsforprotectionagainstover-voltages.] 6.8.4Theuseof structuralsteelinplaceof,orinconnection with,lightningdownconductorsisnotpermittedunless approvedbytheDistributionCompany.Wheresuch approval is given provision must be made for regular testing of thestructuralearthsystemfromroof leveltoground (e.g. via a separate test cable installed through the building). The Electricity Wiring Regulations 2007 (Revision 1) 616 EarthingStructuralfoundationsorpilesmaybeusedaslightning earthelectrodesif suffcientlyseparatedfromtheMain Earth Electrodes and where inspection / testing points are provided for future maintenance.6.9Functional earthing and high leakage currents6.9.1Functional Earth conductors may be required for purposes such as, but not limited to, radio frequency noise reduction, flters for computers and other equipment with high earth leakage currents.6.9.2Functional Earth conductors must be separate from other partsof theInstallationEarthingsystem,exceptattheir connectiontotheMainEarthTerminalwhereasuitable label must be provided, see Appenix A5(f).6.9.3Equipmentwhichproduceshighearthleakagecurrents (above10 mA)maybeprovidedwithaFunctionalEarth andinanycasemustbeprovidedwithduplicateCircuit EarthConductorstotheMainEarthTerminal.Such equipment must remain connected to Earth at all times to avoid the risk ofelectric shock from Exposed-Metallic-Parts ofthe equipment.[Note: metallic conduit may be considered as one of the duplicate EarthConductorsrequiredforhighleakageequipment. Alternatively, Circuit Earth Conductors in a Ring Circuit are also accepted as providing a duplicate earth path.This requirement safeguards against electric shock due to Indirect Contact if only one Circuit Earth was provided and was damaged or broken.]The Electricity Wiring Regulations 2007 (Revision 1) 626The Electricity Wiring Regulations 2007 (Revision 1) 6377.1Plugs and socket-outlets7.1.1For domestic Installations all single-phase plugs and socket-outletsmustcomplywithBS 1363andbefttedwitha switch.Theuseof anyothertypeof single-phaseplugs andsockets-outlets,suchasBS 546(3roundpins)isnot permitted.[Note: BS 1363 requires plugs to have partly insulated live and neutral pins and include a fuse complying with BS 1362. Socket-outletsarerequiredtohavetamper-proofshuttersonthelive, neutral and Earth connections.]7.1.2For single-phase applications in non-domestic Installations either BS 1363 or BS 546 type plugs and socket-outlets are permitted.However, BS 546 plugs and socket-outlets must berestrictedtospecialistapplicationssuchashighload Appliances (BS 546 15 A plug) or where it is desirable not to intermix certain Appliances, see Appendix A17(a).[Note: examples of the use of BS 546 plugs include table lamps in hotel rooms which are switched from a dedicated lighting Circuit (3 A or 5 A) or self contained air conditioning units (15 A). In the latter case 15 A BS 546 socket-outlets must be supplied from a dedicated Radial Circuit.]7.1.3Theuseof 'Shuko'CEE7/72-pintypeplugsisstrictly prohibited.The use of'Euro' CEE7/16 plugs is permitted only where used with an approved adaptor converting such plugs for use on BS 1363 type socket-outlets, see Appendix A17(a).[Note: adapters must be approved by a recognised international approvals authority such as KEMA, NSAI, ASTA, etc.]7.1.4An allowable exception to clause7.1.1 is the use ofshaver supplyunitsinbathrooms,complyingwithBS3535.For these types ofsocket-outlet, which are supplied by a SELV safetyisolatingtransformer,2-pinunearthedtypeplugs may be used. See Appendix A17(c).Selection ofcomponentsand installation requirementsThe Electricity Wiring Regulations 2007 (Revision 1) 6477.1.5Nosocket-outletsshallbeinstalledinabathroomexcept for a socket-outlet complying with BS 3535 (shaver socket-outlet including a safety isolating transformer).7.1.6Three-phaseandindustrialplugsandsocket-outletsmust complywithBS 4343andBS EN 60309,seeAppendix A17(b).Theratingof three-phasesocket-outletsmust beselectedaccordingtotheloadof theApplianceor equipment to be connected.[Note:BS4343plugsandsocket-outletsarenotfusedandare notshutteredandthereforemustnotbeusedinanydomestic application.]7.1.7Socket-outletsfornormalusemustbepositioned atastandardheightof 300mmor450mmabove foorlevelor100mmaboveworksurfaces,see AppendixA16.Whererequired,lowlevelorskirting heightmaybeused(e.g.inoffces)ataminimumof100 mmabovethefoorlevel,andwhereadequate precautionsaretakenagainstdamage.Accessforlimited abilitypersonsmustbegivendueconsiderationinsuch cases (e.g. alternative socket-outlets provided).7.1.8Floor socket-outlets may be used where there is no undue risk ofwater ingress or fooding and which are designed to relevant international standards.7.1.9Socket-outlets in kitchens must be positioned at least 1.0 m awayfromsourcesof water(e.g.sinks,basins,flterunits, supply taps). 7.1.10The recommended minimum number ofsocket-outlets for domestic Installations is given in Appendix A15.7.1.11Allsocket-outletsinoneroomorserviceareashallbe connected to the same phase.7.1.12Themaximumnumberof single-phasesocket-outletson each Ring or Radial Circuit shall be determined according The Electricity Wiring Regulations 2007 (Revision 1) 657 Componentstotheanticipatedloadandusageof Appliances.The assumed loads given in Guidance Note G2 may be used in the absence ofother loading information.7.1.13Three-phase socket-outlets must be connected on individual Radial Circuits.7.1.14Outdoorsocket-outletsmustbeof theweatherprotected type (IP55) and incorporate a 30 mA RCD, see Guidance Note G7(c).[Note: where a number of outdoor socket-outlets are installed in close proximity, the above requirement may be met by one RCD device serving the group of outlets, provided that the RCD device isreadilyaccessibleandvisibletopersonsusingthesocket-outlets and is clearly labelled.]7.2Switches and isolators7.2.1Allswitchesprovidedforlocalisolationof Appliances andequipment(includinglighting)mustcomplywith BS 3676.Theratingof switchesmustbeselectedbased on the expected load, taking into account any capacitive or inductive effects.7.2.2Foroutdoorlocations,damporwetareas,weather-protected switches must be used (BS 3676).7.2.3Wall-mounted switches must not be installed in bathrooms, showerroomsorotherlocationswherenormalbody resistance is reduced due to the presence ofwater.In such locations, ceiling mounted cord-pull switches may be used orwall-mountedswitchesmaybeusedoutsidetheroom. Wall-mounted switches may be used in kitchens but at least 2 m from a sink or other source ofwater.7.2.4For areas with higher than normal risk offre or explosion gas-sealed switches must be used (BS 5345). For example, in gas storage areas, battery rooms, etc.The Electricity Wiring Regulations 2007 (Revision 1) 6677.2.5Thenormalmountingheightforswitchesshallbe1.3m fromfoorlevel.Othermountingheightsmaybeused wherethereisaspecifcneed,suchas,butnotlimitedto, the prevention ofaccess by children or the requirement for access by disabled persons.7.2.6Switcheswithneonindicatorsmustbeprovidedfor Appliancessuchaswaterheaters,airconditioningunits, fridgesandfreezers,whereavisualindicationof the presence ofpower is desirable.7.2.7Double-poleswitchesmustbeprovidedforwaterheaters, air conditioning units and other fxed Appliances operating with or near water supplies.7.2.8Cookercontrolunits(isolators)fordomesticInstallations mustcomplywithBS 4177.Theuseof cookercontrol unitswithanintegral3-pinsocket-outletisprohibited except where the Final Circuit supplying the cooker control unit is protected by an RCD with a residual current rating of30 mA, in accordance with clause 5.4.9.[Note:inadditiontotheaboverestrictionitisconsidered undesirabletousecookercontrolunitswithintegralsocket-outletswherethereisariskofAppliancesorfexiblecables suppliedbythesocket-outletbeingdamagedbyheatfromthe cooker.]7.2.9Flexible cables from switches or isolators to fxed Appliances (suchaswaterheaters,cookers,etc)mustbeadequately ratedandsecurelyfxedwithapurpose-madefexoutlet plate(whichmaybeintegralwithorseparatefromthe switch or isolator unit).7.3Lighting7.3.1LightingCircuitswillnormallybefedfrom6 A,10 Aor 16 AMCBs from a Final Distribution Board.The Electricity Wiring Regulations 2007 (Revision 1) 677 Components7.3.2Theratingof lightingCircuitsshallbeselectedin accordancewiththenumberof connectionpointstobe supplied, the type and rating ofluminaires to be used, and the Connected Load for the Circuit. A standard method ofcalculating Connected Load is given in Guidance Note G2 and illustrated in Appendix A20(f).7.3.3LightingCircuitssupplyingsmallEdisonscrew(SES)or smallbayonetcap(SBC)fttingsmustbesuppliedfrom ProtectiveDevicesof nominalcurrentratingnogreater than 6 A.7.3.4Switchingof Circuitscontainingdischargelightingor otherlightingwithhighinductancemayrequirespecial consideration due to high switching voltages that may occur. In order to accommodate the switching voltage in discharge lighting Circuits, the rating ofthe switch shall be suited to the conditions expected and shall not be less than twice the load current. 7.3.5Highvoltagedischargelighting(suchasneonsigns)must complywithBS 559andbeprovidedwithanemergency isolation switch which must be clearly marked and located in an easily accessible position.[Note: such switches may be marked Firemans Switch for Neon Sign or similar wording.]7.3.6Theconnectionof mains-operatedclockstolighting Circuitsotherthanthroughaclockconnectorunitis prohibited.7.3.7AllLuminairesmustbeconnectedtoFinalCircuitsusing aceilingroseorotherpurposemadeconnectionpoint andnotdirectlytosuchCircuits.Wherecablesarerun within Luminaires they shall be ofthe heat resistant type, orprotectedbyheatresistantsleeving.SeeGuidance Note G7(b).The Electricity Wiring Regulations 2007 (Revision 1) 6877.3.8Lighting Circuits in false ceilings or voids must be installed in conduit or trunking in compliance with clauses7.5.12 and 7.5.13.However,shortlengths(lessthan3 m)of fexible orsheathedcablesmaybeprovidedbetweenalighting connection point or ceiling rose and a Luminaire, provided thatprovisionismadeforfutureaccessandmaintenance. Inaddition,theuseof purposemadeplugandsocket connectionsystemsforLuminairesisnotprecluded, providedthatapprovalissoughtfromtheDistribution Company. See Guidance Note G7(h).7.3.9Luminaires and other light fttings must be installed with due consideration to the weight taken by fxings and supports, and the need for adequate ventilation and heat dissipation.7.3.10Heatresistantcablesandfexiblecordsshouldbeused fortheconnectionof hightemperatureluminaires.See Guidance Note G7(b).7.3.11Where light switch boxes contain more than one phase (for largegroupsof lighting)theymustbelabelledtoindicate the presence ofa 400 V supply, and suitable phase barriers should be provided inside the box.7.3.12Outdoorlightingshouldbeof suitableweatherproofconstructionwithappropriateconnectionpointsand fttings.7.3.13UnderwaterlightingmustbesuppliedbyaSeparated Extra-Low Voltage System (SELV) not exceeding 12 V a.c. or 30 V d.c.7.3.14EmergencylightfttingsmustcomplywithBS 5266and shallbeprovidedwithabatteryof minimum2hours rating.7.4Conduit, trunking and cable trays7.4.1All plastic conduit and trunking must comply with BS 4607 and be suitable for the ambient conditions expected.The Electricity Wiring Regulations 2007 (Revision 1) 697 Components7.4.2Allmetalconduitandtrunkingmustcomplywitheither BS 4568, BS EN 60423 or BS EN 50086.Cable tray must comply with BS EN 61537.7.4.3Flexibleconduitmustbeof metalconstruction,PVC covered and comply with BS 731 part 1.Flexible conduit maybeof plasticconstructiononlyinindoorlocations, wheredamageisunlikelyandwhereitcontainsonly sheathed conductors or Earth Conductors.7.4.4Metalconduit,trunkingorcabletraymaynot,ontheir own,beusedasCircuitEarthConductors;separate Circuit Earth Conductors must be run inside the conduit, trunkingorcabletray,seealsoclause 6.5.10.Thisdoes notobviatetherequirementtocomplywithclause 6.6.1 (i.e.metalconduitsarerequiredtobeEarthed),see Guidance Note G7(j).7.4.5Plasticconduitortrunkingmustnotbeusedinsituations subjecttohigherthannormaltemperaturesorfrerisk (e.g.nearindustrialmachinery,generatorrooms, workshops,petrolstations,etc).Whereplasticconduitis installed outdoors it should be suitable for exposure to solar radiation.7.4.6Where conduit is installed within a wall, foor or ceiling it must be at a minimum depth of50 mm from the surface.Ifit is installed at a shallower depth then metal conduit must be used. See Guidance Note G7(e).[Note: for a solid wall, foor or ceiling the above required depth maybereducedto25mmforlengthsofconduitwhichare within 4 m of a visible Accessory or connection point, or where theCircuitscontainedintheconduitareprotectedbya30mA RCD.]7.4.7Conduit,trunkingandcabletraymustbeinstalledsoas toprovideeaseof accesstocable Circuitsthroughoutthe route.Suffcient inspection plates and pulling points must be provided to enable inspection, repair and drawing out ofcables throughout the life ofthe Installation.The Electricity Wiring Regulations 2007 (Revision 1) 7077.4.8Theendsof conduit,trunkingandcabletrayshall beprovidedwithbushesorotherfnishedendssuch thatcablesdonotsustaindamageduringinstallation orthroughoutthelifeof theInstallation,andmustbe suitablysealedagainsttheingressof water.Wheresuch bushesorendsarenotprovidedanysharpangles,burrs orprojectionsmustberemoved,seeGuidanceNote G7(g).Caremustbetakennottoleavesectionsof cable exposedatendsof conduitortrunking.SeeGuidance Note G7(a).7.4.9Plasticconduitboxesforaccessoriesshallbeprovided withcopperorbrassearthterminals.See