,18th Edition
IET Wiring Regulations
Electric Wiring for Domestic Installers
This book is essential reading for anyone studying towards Domes-
tic Installer status with an approval body such as NICEIC, NAPIT or
ELECSA, in line with Part P of the Building Regulations, and also serves
as a handy pocket guide to best practice for electricians. Although not
intended as a DIY manual, non-qualified persons will also find it useful
reading.
ƒ The how-to guide for home wiring to professional standards.
ƒ Now with more on LED lighting.
ƒ Essential reading for serious DIY, electrical installation, basic
plumbing, heating systems, TV and security alarm installation
ƒ Up to date with the 18th Edition of the IET Wiring Regulations.
Brian Scaddan, I Eng, MIET, is an Honorary Member of City & Guilds
and has over 45 years’ experience in further education and training. He
was Director of Brian Scaddan Associates Ltd, an approved training centre
offering courses on all aspects of electrical installation contracting, includ-
ing those for City & Guilds and EAL. He is also a leading author of books
on other installation topics.
,By the same author
18th Edition IET Wiring Regulations: Design and
Verification of Electrical Installations, 9th ed,
978-1-138-60600-5
18th Edition IET Wiring Regulations: Explained and
Illustrated, 11th ed, 978-1-138-60605-0
18th Edition IET Wiring Regulations: Inspection, Testing
and Certification, 9th ed, 978-1-138-60607-4
18th Edition IET Wiring Regulations: Wiring Systems
and Fault Finding for Installation Electricians, 7th ed,
978-1-138-60609-8
Electrical Installation Work, 8th ed, 978-1-138-84927-3
PAT: Portable Appliance Testing, 4th ed,
978-1-138-84929-7
The Dictionary of Electrical Installation Work,
978-0-08-096937-4
,18th Edition
IET Wiring Regulations
Electric Wiring for Domestic Installers
16th Edition
Brian Scaddan
,Sixteenth edition published 2019
by Routledge
2 Park Square, Milton Park, Abingdon, Oxon, OX14 4RN
and by Routledge
52 Vanderbilt Avenue, New York, NY 10017
Routledge is an imprint of the Taylor & Francis Group, an informa business
© 2019 Brian Scaddan
The right of Brian Scaddan to be identified as author of this work has been asserted by
him in accordance with sections 77 and 78 of the Copyright, Designs and Patents Act
1988.
All rights reserved. No part of this book may be reprinted or reproduced or utilised in
any form or by any electronic, mechanical, or other means, now known or hereafter
invented, including photocopying and recording, or in any information storage or
retrieval system, without permission in writing from the publishers.
Trademark notice: Product or corporate names may be trademarks or registered trade-
marks, and are used only for identification and explanation without intent to infringe.
First edition published 1940 by Newnes, an imprint of Elsevier
Fifteenth edition published by Routledge 2015
British Library Cataloguing-in-Publication Data
A catalogue record for this book is available from the British Library
Library of Congress Cataloging-in-Publication Data
A catalog record has been requested for this book
ISBN: 978-1-138-60604-3 (hbk)
ISBN: 978-1-138-60602-9 (pbk)
ISBN: 978-0-429-46691-5 (ebk)
Typeset in Kuenstler 480 and Trade Gothic by
Servis Filmsetting Ltd, Stockport, Cheshire
,Contents
PREFACE ......................................................................................................... vii
CHAPTER 1 The UK Generation, Transmission and Distribution System .............1
Voltage Bands ....................................................................................................2
The Electricity Safety, Quality and Continuity Regulations 2002 (ESQCR) .............5
The Electricity at Work Regulations 1989 ............................................................5
The IET Wiring Regulations (BS 7671)................................................................5
The Building Regulations 2010 Part ‘P’ ..............................................................6
Earthing Systems ...............................................................................................7
CHAPTER 2 Domestic Electrical Installations ...................................................11
The Main Intake Position ..................................................................................11
Circuits ............................................................................................................17
Cables .............................................................................................................30
Wiring Systems and Installation Methods ..........................................................34
CHAPTER 3 The Importance of Earthing and Bonding .....................................49
Electric Shock ..................................................................................................49
Basic Protection ...............................................................................................51
Fault Protection................................................................................................51
What is Earth and Why and How Do We Connect to It?......................................52
Residual Current Devices .................................................................................59
Bonding: Questions and Answers .....................................................................61
The Faraday Cage ............................................................................................62
CHAPTER 4 Bathrooms...................................................................................63
Zone 0 .............................................................................................................63
Zone 1 .............................................................................................................64
Zone 2 .............................................................................................................65
Supplementary Equipotential Bonding ..............................................................66
CHAPTER 5 Protection ....................................................................................67
Protection Against Mechanical Damage ............................................................68
Protection of Persons/Livestock Against Dangers ..............................................70
v
,vi Contents
CHAPTER 6 Circuit Design ..............................................................................79
Diversity ...........................................................................................................80
Basic Circuit Design .........................................................................................82
Summary .........................................................................................................93
CHAPTER 7 Inspection and Testing .................................................................95
Instruments .....................................................................................................95
Testing ...........................................................................................................101
CHAPTER 8 Security Alarm and Telephone Systems ......................................121
Security Alarms ..............................................................................................121
Telephone Systems ........................................................................................123
APPENDIX 1 Basic Electrical Theory Revision................................................127
Electrical Quantities and Units ........................................................................127
Power, Current and Voltage ............................................................................131
APPENDIX 2 Conductor Identification, Notices and Warning Labels ...............133
Conductor Identification .................................................................................133
Notices and Warning Labels ...........................................................................134
INDEX ..........................................................................................................135
,Preface
This book is a guide to the practical aspects of domestic electric wiring.
It seeks to address the areas of most concern to the qualified electri-
cian, especially design and testing. It will also be a useful addition to the
resources available for students working towards NVQs or City & Guilds
and EAL qualifications.
It is also a vital reference source for many other professionals and opera-
tives whose work demands a knowledge of electrical installations, includ-
ing electrical engineers, heating engineers, architects and maintenance
staff. The contents will be of value to those intending to gain a Domestic
Installer Scheme Qualification which relates to Part ‘P’ of the Building
Regulations. It is not intended as a DIY manual, although some non-qual-
ified persons may find certain topics useful before calling in qualified
operatives.
The contents of this new edition cover current professional best practice
and are fully compliant with the 18th Edition IET Wiring Regulations.
Brian Scaddan
vii
,
, CHAPTER 2
1
The UK Generation,
Transmission and Distribution
System
Important terms/topics covered in this chapter:
ƒ Voltage bands
ƒ The Electricity Safety Quality and Continuity Regulations (ESQCR)
ƒ BS 7671: 2018 The Wiring Regulations
ƒ The Electricity at Work Regulations (EAWR)
ƒ The Building Regulations
ƒ TT, TN-S and TN-C-S earthing systems
By the end of this chapter the reader should:
ƒ know the regulations and recommendations relating to electrical
installations,
ƒ be aware of the Building Regulations relevant to electrical installa-
tions in dwellings,
ƒ be aware of the notifiable work under Part ‘P’ of the Building
Regulations,
ƒ understand the arrangements of the UK earthing systems.
In the early days of electricity supply, each town or city in the United
Kingdom had its own power station which supplied the needs of its
particular area.
Standardization was not evident and many different voltages and
frequencies were used throughout the country. By the time of the First
World War (1914–1918), there were some 600 independent power
stations in use. However, the heavy demands made by the war indus-
try showed the inadequacies of the system and several select commit-
tees were set up to investigate possible changes. Little was achieved until
1926, when it was suggested that 126 of the largest and most efficient
power stations should be selected and connected by a grid of high-voltage
18th Edition IET Wiring Regulations: Electric Wiring for Domestic Installers. 978-1-138-60604-3.
© Brian Scaddan. Published by Taylor & Francis. All rights reserved. 1
IET Wiring Regulations
Electric Wiring for Domestic Installers
This book is essential reading for anyone studying towards Domes-
tic Installer status with an approval body such as NICEIC, NAPIT or
ELECSA, in line with Part P of the Building Regulations, and also serves
as a handy pocket guide to best practice for electricians. Although not
intended as a DIY manual, non-qualified persons will also find it useful
reading.
ƒ The how-to guide for home wiring to professional standards.
ƒ Now with more on LED lighting.
ƒ Essential reading for serious DIY, electrical installation, basic
plumbing, heating systems, TV and security alarm installation
ƒ Up to date with the 18th Edition of the IET Wiring Regulations.
Brian Scaddan, I Eng, MIET, is an Honorary Member of City & Guilds
and has over 45 years’ experience in further education and training. He
was Director of Brian Scaddan Associates Ltd, an approved training centre
offering courses on all aspects of electrical installation contracting, includ-
ing those for City & Guilds and EAL. He is also a leading author of books
on other installation topics.
,By the same author
18th Edition IET Wiring Regulations: Design and
Verification of Electrical Installations, 9th ed,
978-1-138-60600-5
18th Edition IET Wiring Regulations: Explained and
Illustrated, 11th ed, 978-1-138-60605-0
18th Edition IET Wiring Regulations: Inspection, Testing
and Certification, 9th ed, 978-1-138-60607-4
18th Edition IET Wiring Regulations: Wiring Systems
and Fault Finding for Installation Electricians, 7th ed,
978-1-138-60609-8
Electrical Installation Work, 8th ed, 978-1-138-84927-3
PAT: Portable Appliance Testing, 4th ed,
978-1-138-84929-7
The Dictionary of Electrical Installation Work,
978-0-08-096937-4
,18th Edition
IET Wiring Regulations
Electric Wiring for Domestic Installers
16th Edition
Brian Scaddan
,Sixteenth edition published 2019
by Routledge
2 Park Square, Milton Park, Abingdon, Oxon, OX14 4RN
and by Routledge
52 Vanderbilt Avenue, New York, NY 10017
Routledge is an imprint of the Taylor & Francis Group, an informa business
© 2019 Brian Scaddan
The right of Brian Scaddan to be identified as author of this work has been asserted by
him in accordance with sections 77 and 78 of the Copyright, Designs and Patents Act
1988.
All rights reserved. No part of this book may be reprinted or reproduced or utilised in
any form or by any electronic, mechanical, or other means, now known or hereafter
invented, including photocopying and recording, or in any information storage or
retrieval system, without permission in writing from the publishers.
Trademark notice: Product or corporate names may be trademarks or registered trade-
marks, and are used only for identification and explanation without intent to infringe.
First edition published 1940 by Newnes, an imprint of Elsevier
Fifteenth edition published by Routledge 2015
British Library Cataloguing-in-Publication Data
A catalogue record for this book is available from the British Library
Library of Congress Cataloging-in-Publication Data
A catalog record has been requested for this book
ISBN: 978-1-138-60604-3 (hbk)
ISBN: 978-1-138-60602-9 (pbk)
ISBN: 978-0-429-46691-5 (ebk)
Typeset in Kuenstler 480 and Trade Gothic by
Servis Filmsetting Ltd, Stockport, Cheshire
,Contents
PREFACE ......................................................................................................... vii
CHAPTER 1 The UK Generation, Transmission and Distribution System .............1
Voltage Bands ....................................................................................................2
The Electricity Safety, Quality and Continuity Regulations 2002 (ESQCR) .............5
The Electricity at Work Regulations 1989 ............................................................5
The IET Wiring Regulations (BS 7671)................................................................5
The Building Regulations 2010 Part ‘P’ ..............................................................6
Earthing Systems ...............................................................................................7
CHAPTER 2 Domestic Electrical Installations ...................................................11
The Main Intake Position ..................................................................................11
Circuits ............................................................................................................17
Cables .............................................................................................................30
Wiring Systems and Installation Methods ..........................................................34
CHAPTER 3 The Importance of Earthing and Bonding .....................................49
Electric Shock ..................................................................................................49
Basic Protection ...............................................................................................51
Fault Protection................................................................................................51
What is Earth and Why and How Do We Connect to It?......................................52
Residual Current Devices .................................................................................59
Bonding: Questions and Answers .....................................................................61
The Faraday Cage ............................................................................................62
CHAPTER 4 Bathrooms...................................................................................63
Zone 0 .............................................................................................................63
Zone 1 .............................................................................................................64
Zone 2 .............................................................................................................65
Supplementary Equipotential Bonding ..............................................................66
CHAPTER 5 Protection ....................................................................................67
Protection Against Mechanical Damage ............................................................68
Protection of Persons/Livestock Against Dangers ..............................................70
v
,vi Contents
CHAPTER 6 Circuit Design ..............................................................................79
Diversity ...........................................................................................................80
Basic Circuit Design .........................................................................................82
Summary .........................................................................................................93
CHAPTER 7 Inspection and Testing .................................................................95
Instruments .....................................................................................................95
Testing ...........................................................................................................101
CHAPTER 8 Security Alarm and Telephone Systems ......................................121
Security Alarms ..............................................................................................121
Telephone Systems ........................................................................................123
APPENDIX 1 Basic Electrical Theory Revision................................................127
Electrical Quantities and Units ........................................................................127
Power, Current and Voltage ............................................................................131
APPENDIX 2 Conductor Identification, Notices and Warning Labels ...............133
Conductor Identification .................................................................................133
Notices and Warning Labels ...........................................................................134
INDEX ..........................................................................................................135
,Preface
This book is a guide to the practical aspects of domestic electric wiring.
It seeks to address the areas of most concern to the qualified electri-
cian, especially design and testing. It will also be a useful addition to the
resources available for students working towards NVQs or City & Guilds
and EAL qualifications.
It is also a vital reference source for many other professionals and opera-
tives whose work demands a knowledge of electrical installations, includ-
ing electrical engineers, heating engineers, architects and maintenance
staff. The contents will be of value to those intending to gain a Domestic
Installer Scheme Qualification which relates to Part ‘P’ of the Building
Regulations. It is not intended as a DIY manual, although some non-qual-
ified persons may find certain topics useful before calling in qualified
operatives.
The contents of this new edition cover current professional best practice
and are fully compliant with the 18th Edition IET Wiring Regulations.
Brian Scaddan
vii
,
, CHAPTER 2
1
The UK Generation,
Transmission and Distribution
System
Important terms/topics covered in this chapter:
ƒ Voltage bands
ƒ The Electricity Safety Quality and Continuity Regulations (ESQCR)
ƒ BS 7671: 2018 The Wiring Regulations
ƒ The Electricity at Work Regulations (EAWR)
ƒ The Building Regulations
ƒ TT, TN-S and TN-C-S earthing systems
By the end of this chapter the reader should:
ƒ know the regulations and recommendations relating to electrical
installations,
ƒ be aware of the Building Regulations relevant to electrical installa-
tions in dwellings,
ƒ be aware of the notifiable work under Part ‘P’ of the Building
Regulations,
ƒ understand the arrangements of the UK earthing systems.
In the early days of electricity supply, each town or city in the United
Kingdom had its own power station which supplied the needs of its
particular area.
Standardization was not evident and many different voltages and
frequencies were used throughout the country. By the time of the First
World War (1914–1918), there were some 600 independent power
stations in use. However, the heavy demands made by the war indus-
try showed the inadequacies of the system and several select commit-
tees were set up to investigate possible changes. Little was achieved until
1926, when it was suggested that 126 of the largest and most efficient
power stations should be selected and connected by a grid of high-voltage
18th Edition IET Wiring Regulations: Electric Wiring for Domestic Installers. 978-1-138-60604-3.
© Brian Scaddan. Published by Taylor & Francis. All rights reserved. 1
