A Practical Guide to The Wiring Regulations: 17th Edition IEE Wiring Regulations (BS 7671:2008), 4th Edition

About the authors xvii

Preface to the Fourth Edition xix

Acknowledgements xxi

Notation xxiii

1 Plan and terminology of BS 7671:2008 and supporting publications 1

1.1 Plan of BS 7671:2008 1

1.2 Terminology of BS 7671:2008 5

1.3 Supporting publications 6

2 Electricity, the law, standards and codes of practice 7

2.1 General 7

2.2 Electricity: the hazards 7

2.3 The law 12

2.4 Standards and codes of practice 13

3 Scope, object and fundamental principles 17

3.1 General 17

3.2 Scope 17

3.3 Object and effects 20

3.4 Fundamental principles 21

4 Assessment of general characteristics 29

4.1 General 29

4.2 Loading, maximum demand and diversity 29

4.3 Arrangement of live conductors and type of earthing 35

4.4 Nature of supply 40

4.5 Supplies for safety services and standby purposes 44

4.6 Installation circuit arrangements 44

4.7 External influences 45

4.8 Compatibility 45

4.9 Maintainability 46

5 Protection against electric shock 47

5.1 General 47

5.2 Provisions for basic protection 51

5.3 Protective measure: automatic disconnection of supply 53

5.4 Protective measure: double or reinforced insulation 75

5.5 Protective measure: electrical separation 77

5.6 Protective measure: extra-low voltage provided by SELV or PELV 78

5.7 Additional protection 81

5.8 Obstacles and placing out of reach 82

5.9 Protective measures for application only where the installation is controlled or under the supervision of skilled or instructed persons 83

6 Protection against thermal effects 89

6.1 General 89

6.2 Fire caused by electrical equipment 91

6.3 Precautions where particular risks of danger of fire exist 95

6.4 Burns 100

7 Protection against overcurrent, undervoltage and overvoltage 101

7.1 General 101

7.2 Nature of protective devices 102

7.3 Protection against overload 104

7.4 Protection against fault current 110

7.5 Determination of prospective fault current 112

7.6 Characteristics of protective devices 128

7.7 Overcurrent protection of conductors in parallel 131

7.8 Coordination of overload and fault current protection 134

7.9 Protection according to the nature of circuits and distribution systems 135

7.10 Protection against undervoltage 136

7.11 Protection against overvoltage 137

8 Isolation and switching 139

8.1 General 139

8.2 Main switch 143

8.3 Isolation 145

8.4 Switching off for mechanical maintenance 151

8.5 Emergency switching and other forms of switching for safety 153

8.6 Emergency stopping 157

8.7 Functional switching 158

8.8 Identification and notices 160

9 Equipment selection: common rules 161

9.1 General 161

9.2 Compliance with standards 161

9.3 Operational conditions, external influences and accessibility 162

9.4 Identification and notices 164

9.5 Mutual detrimental influences 176

9.6 Compatibility 178

9.7 Operation and maintenance manual 179

10 Wiring systems 181

10.1 Wiring systems 181

10.2 External influences 185

10.3 Proximity to other services: general 199

10.4 Methods of installation of cables 205

10.5 Resistances of copper conductors 217

10.6 Electrical connections 218

10.7 Cable supports and cable management systems 224

10.8 Minimizing the risk of fire 230

10.9 Electromagnetic and electromechanical effects 231

10.10 Conduit and trunking cable capacities 233

10.11 Maintainability 238

11 Switchgear, protective devices and other equipment 241

11.1 Switchgear and protective devices: general 241

11.2 Switchgear and controlgear 241

11.3 Selection of devices for overload and fault current protection: general 243

11.4 Overcurrent protective devices 247

11.5 Residual current devices 261

11.6 Identification of overcurrent protective devices 271

11.7 Discrimination 272

11.8 Other equipment 279

12 Protective conductors, earthing and equipotential bonding 289

12.1 Protective conductors 289

12.2 Earthing 307

12.3 Earthing requirements for the installation of equipment having high protective conductor currents 314

12.4 Protective bonding 318

13 Specialized installations 325

13.1 General 325

13.2 Emergency lighting 325

13.3 Fire detection and alarm systems 326

13.4 Petrol filling stations and liquid petroleum gas stations 331

13.5 Installations in dusty environments 331

13.6 Installations in underground and multistorey car parks, etc 332

13.7 Installations in multi-occupancy blocks of flats 332

13.8 Installations in ‘Section 20 buildings’ 332

13.9 Installations in churches 334

13.10 Installations in thatched properties 334

13.11 Extra-low voltage lighting 335

13.12 Outdoor lighting installations, highway power supplies and street furniture 338

13.13 Security lighting 341

13.14 Welding equipment 342

13.15 Entertainers’ equipment 342

13.16 Generator sets 342

14 Safety services 347

14.1 Safety services: general 347

14.2 Common sources 348

14.3 Parallel and nonparallel sources 350

14.4 Circuit and equipment requirements 351

14.5 Protection against overcurrent and electric shock under fault conditions 351

15 The smaller installation 353

15.1 Scope 353

15.2 The IEE On-Site Guide and the NICEIC Domestic Electrical Installation Guide 353

15.3 User’s requirements 353

15.4 Wiring systems 355

15.5 Electricity distributor’s requirements 355

15.6 Assessment of supply characteristics 355

15.7 ‘Meter tails’ 356

15.8 System earthing arrangements 357

15.9 Main protective bonding 360

15.10 Minimum cross-sectional area of earthing and main protective bonding conductors 360

15.11 Supplementary bonding 362

15.12 Devices for protection against overcurrent and for fault protection 362

15.13 Devices for isolation and switching 363

15.14 Final circuit design 363

15.15 Remote buildings 384

15.16 Minimum number of socket-outlets in domestic premises 385

15.17 Modifications to existing installations 385

15.18 Inspection, testing, verification and certification of the smaller installation 387

16 Special installations and locations 389

16.1 General 389

16.2 Locations containing a bath or shower 389

16.3 Swimming pools and other basins 398

16.4 Rooms and cabins containing sauna heaters 407

16.5 Construction-site installations 407

16.6 Agricultural and horticultural premises 413

16.7 Conducting locations with restricted movement 421

16.8 Electrical installations in caravan/camping parks and similar locations 422

16.9 Marinas and similar locations 429

16.10 Exhibition shows and stands 430

16.11 Solar photovoltaic power supply systems 435

16.12 Mobile or transportable units 440

16.13 Electrical installations in caravans and motor caravans 445

16.14 Temporary electrical installations for structures, amusement devices and booths at fairgrounds, amusement parks and circuses 451

16.15 Floor and ceiling heating systems 452

17 Inspection, testing, certification and reporting 459

17.1 Inspection, testing, certification and reporting: general 459

17.2 Test instruments 459

17.3 Safety in electrical testing 462

17.4 Test methods 463

17.5 Initial verification 483

17.6 Periodic inspection and testing 512

17.7 Alterations and additions 534

17.8 Inspection, testing and certification of specialized installations 535

Appendix Standards to which reference has been made 537

Bibliography 545

Index of figures 547

Index of tables 551

Index of regulation numbers 557

Subject index 579