Electrical Installation Designs, Fourth Edition

264 Pages·2013·5.27 MB·English

by  Bill Atkinson

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Electrical InstallationDesigns
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Electrical Installation Designs
Fourth Edition
BillAtkinson
Deceased
RogerLovegrove
ElectricalContractors’ Association,UK
GaryGundry
TheElectricalSafetyCouncil,UK
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Thiseditionfirstpublished2013
#2013,JohnWiley&Sons,Ltd
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Allrightsreserved.Nopartofthispublicationmaybereproduced,storedinaretrievalsystem,ortransmitted,inanyformorbyany
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LibraryofCongressCataloging-in-PublicationData
Electricalinstallationdesigns/BillAtkinson...[etal.].–4thed.
p.cm.
Includesbibliographicalreferencesandindex.
ISBN978-1-119-99284-4(pbk.)
1. Electricwiring,Interior. 2. Electricalengineering. I. Atkinson,Bill.
TK3271.A82013
621.319’24–dc23
2012030909
AcataloguerecordforthisbookisavailablefromtheBritishLibrary.
ISBN:978-1-119-99284-4
Setin10/12ptSabon-RomanbyThomsonDigital,Noida,India.
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Contents
AbouttheAuthors xvii
PrefacetotheFourthEdition xix
Acknowledgements xxv
1 Introduction 1
1.1 Layoutofchapters 1
1.2 Wiringregulations 2
1.3 Terminology 2
1.4 Competenceandresponsibility 3
1.5 Procedures 3
1.5.1 Design 3
1.5.2 Installation 4
1.6 Inspectionandtest 4
1.7 Completion 5
1.8 Workingmethodsandmaterials 5
1.9 Operatives 5
1.10 Materials 5
1.11 AmendmentstoBS7671:2008 6
1.12 Voltages 6
1.13 Voltagedrop 6
2 ThreeBedroomHouse 8
2.1 Thebareminimum 9
2.2 Standards 9
2.2.1 NationalHouseBuildingCouncil(NHBC) 9
2.2.2 Relevantwiringregulations 9
2.3 Buildingregulations 11
2.3.1 Smokedetectors 11
2.4 Loadassessment 11
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Contents
2.5 Atypicaldomesticsupply 12
2.6 Projectspecification 12
2.7 Wiringsystemsandcablesizes 12
2.8 Lighting 12
2.9 13Asocket-outlets 13
2.10 Cablesizes 15
2.11 Circuitprotection 15
2.11.1 Rewireablefuses 15
2.11.2 Cartridgefuses 15
2.11.3 Circuit-breakers(cb) 15
2.12 Additionalprotectionforsocket-outlets 15
2.13 Arrangementofcircuits 16
2.13.1 Residualcurrentprotection 16
2.13.2 Circuit-breakers(cb) 16
2.14 Arrangementofconsumerunit 16
2.15 Mainswitch 17
2.16 Earthingandbonding 17
2.17 Gasservicesbondingandexternalmeters 18
2.18 Supplementarybonding 19
3 ABlockofRetirementFlatlets 21
3.1 Twoschemes 21
3.2 Earlyconsiderations 21
3.2.1 Meteringanddistribution 21
3.3 Otherinterestedparties 22
3.4 Buildingdetails 22
3.4.1 Construction 22
3.5 Part1–Flats 24
3.5.1 Mainsdistribution 24
3.5.2 Electricalrequirementsinflats 24
3.5.3 Loadassessmentandmaximumdemand 25
3.5.4 Wiringsystem 25
3.5.5 Wiringhints 25
3.5.6 Wiringinfalseceilings 26
3.5.7 Wiringinroofspace 27
3.5.8 Cablesizes 27
3.5.9 Arrangementofcircuits 27
3.5.10 Consumerunit 28
3.5.11 Earthingandbonding 28
3.5.12 Earthingterminal 29
3.5.13 Bonding 29
3.6 Part2–Landlord’sareas 29
3.6.1 Metercupboard 29
3.6.2 Suppliestoflats 29
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Contents
3.6.3 Landlord’selectricalrequirements 30
3.6.4 Diversity 30
3.6.5 Lighting 31
3.6.6 Socket-outlets 31
3.6.7 Otherequipment 31
3.6.8 Totalload 31
3.6.9 Cablesizesandcircuitry 31
3.6.10 Lighting 32
3.6.11 Socket-outlets 32
3.6.12 Otherequipment 33
3.6.13 Distributionboard 33
3.6.14 Residualcurrentprotection 33
3.6.15 Switchgear 33
3.6.16 Switching 34
3.6.17 Wiring 34
3.6.18 Earthing 34
3.6.19 Emergencysystems 34
4 OvercurrentProtection 35
4.1 Overload 35
4.2 Overloadprotection 36
4.3 Overloadprotectivedevices 37
4.3.1 Rewirablefuses 37
4.3.2 HighBreakingCapacity(HBC)fuses 37
4.3.3 Circuit-breakers 37
4.3.4 The‘type’ofcircuit-breaker 37
4.4 Faultcurrent 38
4.5 FaultCurrentProtection 39
4.6 Omissionoffaultcurrentprotection 39
4.7 Short-circuitrating 39
4.8 Disconnectiontimes 41
4.9 Earthloopimpedance 42
4.10 Summaryofcbspecification 42
4.11 Conclusion 43
5 AnArchitect’sOffice 44
5.1 Otherinterestedparties 44
5.2 Buildingstructureandfinishes 45
5.3 Electricalrequirements 46
5.3.1 Loadinganddiversity 47
5.3.2 Storageheaters 49
5.3.3 Printmachine 50
5.3.4 Socket-outlets 50
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Contents
5.3.5 Totalload 50
5.3.6 Wiringsystem 50
5.4 Skirtingsystem 51
5.5 Underfloorsystem 51
5.6 Socket-outlets 51
5.7 Lightingcircuits 51
5.8 Battenedoutceilings 52
5.9 Extra-LowVoltagelighting(elv) 52
5.10 Grouptransformers 53
5.11 Individualtransformers 53
5.12 Fireprevention 53
5.13 Arrangementofcircuits 53
5.14 Distributionboards 54
5.15 Cablesizes 55
5.16 Switchgear 55
5.17 Printmachine 57
5.18 Wallheatersintoilets 57
5.19 Storageheaters 57
5.20 Presenceof400Volts 58
5.21 Accesstoswitchgear 58
5.22 Earthingandbonding 58
5.23 Mainearthingterminal 58
5.24 Falseceilinggrid 59
5.25 Computerinstallations 60
5.25.1 Computersupplies 60
5.26 Highprotectiveconductorcurrents 60
5.27 Mainsfilters 60
5.28 UninterruptiblePowerSupplies(UPS) 61
6 AHighStreetShop 62
6.1 Specialconsiderations 62
6.2 Otherinterestedparties 63
6.3 Buildingstructureandfinishes 63
6.4 Electricalrequirements 63
6.5 Loadinganddiversity 63
6.6 Lighting 65
6.7 Socket-outlets 66
6.8 Otherappliances 67
6.9 Phasebalance 68
6.10 Wiringsystems 68
6.11 Startbyconsideringcost 69
6.12 Shoparea 69
6.13 Bakeryarea 69
6.14 Temperaturelimitof70(cid:1)C 70
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Contents
6.15 Temperaturelimitof90(cid:1)C 70
6.16 Finalselectionandcablesizes 70
6.17 Bakerywiring 70
6.18 Shopwiring 71
6.19 Distributionboard 71
6.20 Cablesizes 72
6.21 Switchgear 73
6.22 Isolationandswitching 73
6.22.1 Mainswitch 73
6.22.2 Appliances 73
6.23 Earthingandbonding 73
6.24 Mainearthingterminal(MET) 73
6.25 False-ceilinggrid 74
6.26 Steeltablesinthebakery 74
7 EarthingandBonding 75
7.1 Terminology 75
7.2 Definitions 76
7.3 Green-and-yellowconductors 76
7.4 Protectiveearthingandprotectiveequipotentialbonding 77
7.5 ProtectiveMultipleEarthing(PME) 77
7.5.1 Whyearthatall? 77
7.6 Reliabilityoftheearth-neutralpath 78
7.7 Mainbonding 79
7.8 Singlefaultcondition 81
7.9 Supplementarybonding 82
7.10 CircuitProtectiveConductors(CPCs) 82
7.11 Steelconduitandtrunking 83
7.12 Steelwirearmouredcable 84
7.13 Comparisonofthermoplastic(PVC)andthermosetting(XLPE)
armouredcable 84
7.14 Continuityofcableglands 84
7.15 Equipmenthavinghighprotectiveconductorcurrents 86
7.16 Protectiveconductorcurrents 86
7.16.1 Itemsofstationaryequipment 87
7.17 ‘Highintegrity’earthing 87
7.18 Earthmonitoringandisolatedsupplies 87
7.19 Socket-outletsfordesktopcomputers 88
7.20 Connectionsofprotectiveconductors 89
7.21 Residualcurrentdevices 89
8 CarServiceWorkshop 90
8.1 Standardsandrecommendations 90
8.2 Anadaptabledesign 91
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Contents
8.3 Motorvehiclerepairpremises 91
8.4 Otherinterestedparties 91
8.5 Buildingstructureandfinishes 91
8.6 Construction 94
8.7 Electricalrequirements 94
8.8 Healthandsafetyexecutiveguidanceandregulations 94
8.9 HealthandsafetyguidancenoteHSG261 95
8.10 Wiringregulations 96
8.11 Loadassessmentandmaximumdemand 96
8.12 Maximumdemandloadanddiversity 96
8.13 Lighting 97
8.13.1 Officelightingload 99
8.13.2 Workshoplightingload 99
8.14 Welder 99
8.15 Compressor 99
8.16 Gasblowers 100
8.16.1 Provisionforsprayarea 100
8.17 Phasebalance 100
8.18 Estimateofmaximumdemand 101
8.19 Whataboutadistributioncircuit(sub-main)? 102
8.20 Wiringsystems 102
8.21 Workshop 102
8.21.1 Steelconduitandtrunking 102
8.21.2 SteelWireArmoured(SWA)cable 103
8.22 Office 105
8.23 Arrangementofcircuits 105
8.24 Distributionboards 105
8.25 Cablesizes 105
8.26 Isolationandswitching 107
8.27 Machinery 107
8.28 Cooker 107
8.29 Gasboiler 107
8.30 110Vtransformer 108
8.31 Earthingandbonding 108
8.32 Mainearthingterminal 109
8.33 ProtectiveconductorsatdistributionboardB 109
8.34 Armouredcableglands 109
8.35 Steelconduitandtrunking 110
9 Circuits 111
9.1 Terminology 111
9.2 Coloursofthreephases 111
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Contents
9.3 Conventionalcircuits 112
9.4 Lightingcircuits 112
9.5 Induction 113
9.6 Socket-outletcircuits 113
9.7 Changingmethods 113
9.8 Ringmainobsolescence 113
9.9 Historyoftheringfinalcircuit 114
9.10 Timeshavechanged 114
9.11 Alternativemethods 116
9.11.1 Multipleplugsizes 116
9.12 Radialcircuits 117
9.13 Introducingthetree 117
9.14 20Atree 117
9.14.1 Domestic 117
9.14.2 Commercialandsimilar 117
9.15 32Atree 118
9.15.1 Domestic 119
9.15.2 Commercialandsimilar 119
9.16 Switchingandcontrol 119
9.17 Comparisonofsystems 120
9.18 32Aringfinalcircuit 120
9.18.1 Disadvantages 120
9.18.2 Advantage 120
9.19 20Atree 121
9.19.1 Disadvantage 121
9.19.2 Advantages 121
9.20 Compositecircuits 121
10 FarmingandHorticulture 123
10.1 Whyfarmsaredifferent 124
10.1.1 Environment 124
10.1.2 Livestock 124
10.1.3 Equipotentialzones 124
10.1.4 Electricalsystems 125
10.2 SpecialearthingrequirementsonfarmswithTTsystems 126
10.2.1 Warning 126
10.3 Earthelectrodes 127
10.4 Alternativeelectrodes 127
10.4.1 Earthtapesandwires 127
10.4.2 Structuralsteelwork 128
10.4.3 Concretereinforcement 128
10.4.4 Earthinggridsorplates 128
10.4.5 Pipeworkofotherservices 128
xi