HANDBOOK OFELECTRICAL

INSTALLATIONPRACTICE

FOURTH EDITION

Edited by

Eur Ing GEOFFREY STOKESBSc(Hons), CEng, FIEE, FCIBSE

BlackwellScience

HANDBOOK OFELECTRICAL INSTALLATION

PRACTICE

HANDBOOK OFELECTRICAL

INSTALLATIONPRACTICE

FOURTH EDITION

Edited by

Eur Ing GEOFFREY STOKESBSc(Hons), CEng, FIEE, FCIBSE

BlackwellScience

© 2003 by Blackwell Science Ltd,a Blackwell Publishing CompanyEditorial Offices:9600 Garsington Road, Oxford OX4 2DQ

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Contents

Preface xiii

1 Power Supplies in the UK 1g.s. finlay

NETA 6Voltage and frequency 6System impedance and short-circuit levels 8Loading effects on the system 9Superimposed signals 11Radio teleswitching 12System and installation earthing 14Protection 16Reliability 17Embedded generation 19Supply arrangements 21Intake arrangements 24Consumers’ substations 28h.v. or l.v. supply 28Metering 28

2 Substations and Control Rooms 33d .m . barr

Introduction 33Substations 37Enclosures 42Substation cabling 45Installation 55Erection procedures 58

3 Site Distribution Systems 67m .g . twitchett

Intake arrangements 68Site distribution networks 70On-site generation 72Switchgear 74Cables 76Cables installation 77Provision for maintenance 77

v

System operation 79Identification of substations and switchgear 79Faults level 81Testing and commissioning 83

4 Cable Management Systems 84m . j . dyer

Introduction 84Decision making 86Definitions 86Types of system 87Underfloor systems 88Cable tray and cable basket 90Hybrid systems 91Conduit and trunking 92Overall considerations 94Particular considerations 95Segregation 96

5 Electricity on Construction Sites 98g . stokes

Equipment design and manufacture 99Range of equipment 99Design of system 107Supply systems 110Selection of equipment 112Cable routing 117Construction site lighting 119Testing and inspection 120Installation maintenance 121

6 Standby Power Supplies 122g .m . mcdowell

Standby diesel generating sets 122Batteries for static systems 138d.c. standby systems 140Alternating current systems 146Composite standby systems 159

7 Ground Earthing 162t .e . charlton and j .r . wales

Introduction 162Soil resistivity 163Resistivity surveying 164Interpreting measurements 167

vi Contents

Resistance measurement of electrode systems 174Types of earth electrodes 175Installation 177Standards applicable to earthing practice 179

8 Cathodic Protection 180j .d . thirkettle

Introduction 180Principles of cathodic protection 183Cathodic protection systems 186Installation practice 188Equipment 191Monitoring, inspection and maintenance 193Interaction 194Protection of steel in concrete 194Recent developments 195Conclusions 195Further information 195

9 Lightning Protection 197j . sherlock and p . woods

Introduction 197Part 1. Protection of structures 197Strike probability 199Installation of lightning protection 218Inspection and testing of a system 219Part 2. Protecting electronic systems from lightning 219

10 Special Installations or Locations 248l .d . markwell

Locations containing a bath tub or a shower basin 249Swimming pools 252Hot air saunas 255Construction site installations 256Agricultural and horticultural premises 258Equipment having high protective conductor currents 261Caravans and motor caravans 261Caravan site supply arrangements 263Highway power supplies and street furniture 264

11 Electrical Safety 267r .t .r . pilling

Legislation 267Safe design and installation 273Maintenance 274

Contents vii

Training and systems of work 275Tools 278Buried cables 279Overhead lines 280Electric shock 281Protection from electric shock 283Burns 293Fires 295Explosions 296Flammable atmospheres 298Conclusion 303

12 Standards, Specifications and Codes of Practice 304m .h . graham

British Electrotechnical Committee (BEC) 305British Standards Institution (BSI) 305The International Electrotechnical Commission (IEC) 308European Committee for Electrotechnical Standardisation

(CENELEC) 310The Institution of Electrical Engineers (IEE) 312Standards and the law 313European Union (EU) 315Conclusion 316

13 Distribution Transformers 318k . frewin

Types of transformer 318Performance 329Tappings and connections 339Cooling 343Impulse withstand 345Operation in tropical climates 346Parallel operation 347Packaged substations 347Protection 348Shipment of transformers 350Installation 352Cabling 353Commissioning 354Maintenance 354

14 Switchgear 358a . headley and r .w . blower

Definitions 358Circuit-breaking 360Medium voltage switchgear 360

viii Contents

Types of switching device 364Comparison of circuit-breaker types 372Specification and testing 372High-voltage circuit-breaker switchboards 380Erection of switchgear 386Electrical testing and commissioning 390

15 Rotating Machines 394g . walton

Motor types 394Variable-speed drives 407Motor application 413Efficiency 417Storage 418Installation 418Commissioning 422Maintenance 423

16 HBC Fuses and Fusegear in Low Voltage Systems 427p .g . newbery

HBC fuselinks design and performance 428Design of cartridge fuse-links 431Overload characteristics 436Fuse-holder 437Application of HBC fuses 437Discrimination and co-ordination 440Fuses in high ambient temperatures 443Protection against electric shock 443Domestic fuse applications 446Semiconductor fuse-links 447Fuse-links for electricity authority networks 447Compact fuses to BS 88: Part 6 448Fuse switchgear 448Thermal ratings 451

17 Motor Control Gear 453t . fairhall

Contactor 454Contactor selection 456Product standards for contactors 460Overload protection 463Starter types 466Isolation 471Enclosures 473

Contents ix

18 Lighting 475h .r . king

The nature of light 475Units of light measurement 477Electric lamps 477Control gear and starting 484Luminaires (lighting fittings) 485Outdoor lighting equipment 489Floodlighting calculations 490Lighting design for interiors 491Emergency lighting 499

19 Mains Cables 502t .l . journeaux

Cable specifications 502Cable conductors 504Insulation 506Cable construction 509Installation 518Jointing and terminating 521Cable ratings 525Testing and fault finding 527

20 Selection of Wiring Systems 529m. coates

Introduction 529Wiring systems 531Construction of wiring cables and flexibles 536Cable enclosure and support systems 538Temperature limits 540Cable ratings 541Factors affecting the selection of types of cable 564Installation methods 578

21 Control and Protection of Low Voltage Installations 585h .r . lovegrove

Isolation and switching 585Protection 590

22 Protective Systems 597p .r . rosen

Protective system requirements 597Unit and non-unit protection 599Graded protection 603

x Contents

Unit protection 608Transformer protection 617Rotating plant 623Relay accommodation 628Commissioning tests 631

23 Power Factor Correction and Tariffs 635t . longland

Importance of power factor 635Theory of power factor correction 636Power factor improvement 636Economic considerations 637Calculation of capacitor size 638Practical power factor improvement 639Capacitor size related to tariff 644Determination of load conditions 647Reduced CO2 emissions 648Methods of correction 648Location of capacitors 652Capacitors and harmonics 653Installation of capacitors 654Capacitor maintenance 657

AppendicesI Main Authoritative Documents 660II IP Codes of Ingress Protection (BS EN 60947–1: 1998) 661III British Standards 665

Index 669

Contents xi

Preface

My first task as editor is to acknowledge and thank my predecessors Alan Smithand Eric Reeves for their work in editing the three previous editions. It is to behoped that they will not disapprove of this latest fourth edition.

Since the third edition was published in 1996, developments in many aspects ofthe electrical installation industry have continued apace, both on the technologicaland Standards fronts.The revolution in electronic microtechnology has made it pos-sible to introduce more complex technologies in protective equipment and controlsystems. This, together with the rationalisation of national, European and interna-tional harmonised Standards, has led to the need to provide new guidance in someareas. So, after seven years, the time is ripe for an update to take account of such developments.

Additionally, since the third edition was published, the political and financialaspects of the supply industry have further escalated, with further fragmentation.Chapter 1 therefore was particularly difficult, trying to take account of the contin-uous change in practice. At the time of writing this book, the replacement of theElectricity Supply Regulations 1988 (as amended) was anticipated. The ElectricitySafety, Quality, and Continuity Regulations came into force on 31 January 2003, butfor the purposes of this book reference is made to the earlier Statutory Regulations.

The effect of changes in the industry over the last few years has meant the updateof nearly all the 23 chapters. It is not possible to highlight here particular alterationsfor they are too numerous. Sections dealing with the safety aspects of electricalinstallations, most particularly Chapter 11, naturally take into account Electricity atWork Regulations. To a great extent these statutory requirements complement BS7671: Requirements for Electrical Installations, known as the IEE Wiring Regula-tions. All chapters required some revision to take account of revisions and amend-ments to British and other Standards. It has to be recognised that, both on Standardsand technology evolution, the target is continually moving. However, every efforthas been made to bring the text as up-to-date as possible.

Over recent years lighting design development has continued. Extra-low voltageluminaires continue to be used extensively for display and feature illumination.Security lighting has now become an industry in its own right, and Chapter 18 takesall these factors into account.

The declared low voltage supply has for a number of years been harmonisedacross Europe to 400/230V with tolerances of +10% and -6%. Further considera-tion of these tolerances is expected in 2008.

Geoffrey Stokes

xiii