17th Edition IEE Wiring Regulations: Design and Verification of Electrical Installations By the same author 17th Edition IEE Wiring Regulations: Inspection, Testing and Certification, ISBN 978-0-7506-8719-5 17th Edition IEE Wiring Regulations: Explained and Illustrated, ISBN 978-0-7506-8720-1 Electric Wiring: Domestic, ISBN 978-0-7506-8735-5 PAT: Portable Appliance Testing, ISBN 978-0-7506-8736-2 Wiring Systems and Fault Finding, ISBN 978-0-7506-8734-8 Electrical Installation Work, ISBN 978-0-7506-8733-1 17th Edition IEE Wiring Regulations: Design and Verification of Electrical Installations Sixth edition Brian Scaddan , IEng, MIET AMSTERDAM • BOSTON • HEIDELBERG • LONDON NEW YORK • OXFORD • PARIS • SAN DIEGO SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO Newnes is an imprint of Elsevier Newnes is an imprint of Elsevier Linacre House, Jordan Hill, Oxford OX2 8DP, UK 30 Corporate Drive, Suite 400, Burlington, MA 01803, USA First published 1995 Reprinted 1996, 1999 Second edition 1999 Third edition 2001 Fourth edition 2002 Reprinted 2002, 2003, 2004 Fifth edition 2005 Sixth edition 2008 Copyright © 2008, Brian Scaddan. Published by Elsevier Ltd. All rights reserved The right of Brian Scaddan to be identified as the author of this work has been asserted in accordance with the Copyright, Designs and Patents Act 1988 No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means electronic, mechanical, photocopying, recording or otherwise without the prior written permission of the publisher Permissions may be sought directly from Elsevier’s Science & Technology Rights Department in Oxford, UK: phone ((cid:2) 44) (0) 1865 843830; fax ((cid:2) 44) (0) 1865 853333; email: [email protected]. Alternatively you can submit your request online by visiting the Elsevier website athttp://elsevier.com/locate/permissions, and selecting Obtaining permission to use Elsevier material Notice No responsibility is assumed by the publisher for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein British Library Cataloguing in Publication Data Scaddan, Brian 17th edition IEE wiring regulations : design and verification of electrical installations. – 6th ed. 1. Electric wiring, Interior – safety regulations – Great Britain 2. Electric wiring, Interior – Handbooks, manuals, etc. I. Title II. Scaddan, Brian. 16th edition IEE wiring regulations III. Institution of Electrical Engineers IV. Seventeenth edition IEE wiring regulations 621.3’1924’0941 Library of Congress Control Number: 2008926538 ISBN: 978-0-7506-8721-8 For information on all Newnes publications visit our website atwww.elsevierdirect.com Typeset by Charon Tec Ltd., A Macmillan Company. (www.macmillansolutions.com) Printed and bound in Slovenia 08 09 10 11 11 10 9 8 7 6 5 4 3 2 1 In memory of Ted Stocks A friend and colleague This page intentionally left blank 17th Edition IEE Wiring Regulations vii Contents PREFACE .............................................................................................ix CHAPTER 1 Design ............................................................................1 Assessment of General Characteristics ..................................................1 Protection for Safety ..............................................................................6 Protection Against Electric Shock ...........................................................7 Protection Against Thermal Effects (IEE Regulations Chapter 42) .........15 Protection Against Overcurrent ............................................................16 Protection Against Overload .................................................................18 Protection Against Fault Current ..........................................................19 Protection Against Undervoltage (IEE Regulations Section 445) ...........23 Protection Against Overvoltage (IEE Regulations Sections 442 and 443) ...............................................23 Isolation and Switching ........................................................................23 Design Calculations .............................................................................25 CHAPTER 2 Inspection and Testing..................................................53 Initial Verification .................................................................................53 Inspection ...........................................................................................54 Testing ................................................................................................54 Approved Test Lamps and Indicators ...................................................55 Calibration, Zeroing/Nulling and Care of Instruments ...........................57 The Tests ............................................................................................58 Continuity of Protective Conductors .....................................................59 Continuity of Ring Final Circuit Conductors ..........................................61 Insulation Resistance ..........................................................................70 Polarity ...............................................................................................72 Ring Final Circuits ...............................................................................72 Radial Circuits .....................................................................................73 Earth Electrode Resistance ..................................................................73 External Loop Impedance Z ................................................................77 e Earth Fault Loop Impedance Z ...........................................................78 s Additional Protection ...........................................................................78 vii viii Contents CHAPTER 3 Special LocationsIEE Regulations Part 7 .......................85 Introduction ........................................................................................85 BS 7671 Section 701: Bathrooms, etc. . ...............................................86 BS 7671 Section 702: Swimming Pools ...............................................89 BS 7671 Section 703: Hot Air Saunas .................................................92 BS 7671 Section 704: Construction Sites.............................................93 BS 7671 Section 705: Agricultural and Horticultural Locations.............95 BS 7671 Section 706: Restrictive Conductive Locations .......................97 BS 7671 Section 708: Caravan and Camping Parks .............................97 BS 7671 Section 709: Marinas ............................................................99 BS 7671 Section 711: Exhibitions, Shows and Stands........................100 BS 7671 Section 712: Solar Photovoltaic (PV) Supply Systems ..........101 BS 7671 Section 717: Mobile or Transportable Units .........................102 BS 7671 Section 721: Caravans and Motor Caravans ........................102 BS 7671 Section 740: Amusement Devices, Fairgrounds, Circuses, etc. ....................................................................................104 BS 7671 Section 753: Floor and Ceiling Heating Systems ..................104 APPENDIX 1 BS 7671 Appendices ................................................107 APPENDIX 2 Sample Questions .....................................................109 APPENDIX 3 Suggested Solutions to Sample Questions ..................115 INDEX...............................................................................................123 Preface There are many electrical operatives who, quite innocently I am sure, select wiring systems based on the old adage of ‘that’s the way it’s always been done ’ or ‘we always use that size of cable for that circuit’ etc. Unfortunately this approach, except for a few standard circuits, is quite wrong. Each wiring system should be designed to be fit for purpose and involves more than arbitrary choices. The intention of this book is to illustrate the correct procedure for basic design of installations from initial assessment to final com- missioning. It will also be of use to candidates studying for a C& G 2391-20 Design qualification. This edition has been revised to serve as an accompaniment to the new City & Guilds scheme and has been brought fully up-to-date with the 17th Edition IEE Wiring Regulations. Brian Scaddan, April 2008 Acknowledgements I would like to thank Paul Clifford for his thorough technical proof reading. ix