Brian Scaddan - IET Wiring Regulations: Wiring Systems and Fault Finding for Installation Electricians

Seventh edition published 2019

by Routledge

2 Park Square, Milton Park, Abingdon, Oxon, OX14 4RN

and by Routledge

52 Vanderbilt Avenue, New York, NY 10017

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 trademarks, and are used only for identification and explanation without intent to infringe.

First edition published 1991 by Newnes, an imprint of Elsevier

Sixth edition published by Routledge 2015

A catalogue record for this book is available from the British Library

A catalog record has been requested for this book

ISBN: 978-1-138-60611-1 (hbk)

ISBN: 978-1-138-60609-8 (pbk)

ISBN: 978-0-429-46687-8 (ebk)

Typeset in Kuenstler 480 and Trade Gothic by

Servis Filmsetting Ltd, Stockport, Cheshire

The aim of this book is to help the reader to approach the drawing and interpretation of electrical diagrams with confidence, to understand the principles of testing and to apply this knowledge to fault finding in electrical circuits.

The abundant colour diagrams with associated comments and explanations lead from the basic symbols and simple circuit and wiring diagrams, through more complex circuitry, to specific types of wiring systems and, finally, to the methodical approach to fault finding.

The new edition has been brought fully in line with the 18th Edition IET Wiring Regulations.

Brian Scaddan

Important terms/topics covered in this chapter:

By the end of this chapter the reader should:

This is an area often overlooked or even ignored. The IET Wiring Regulations require that diagrams, charts, tables or equivalent forms of information are made available to the installer and inspector and tester.

BS EN 60617 gives the graphical symbols that should be used in all electrical/electronic diagrams or drawings. Since the symbols fall in line with the International Electrotechnical Commission (IEC) document 617, it should be possible to interpret non-UK diagrams. Samples of the symbols used in this book are shown in .

FIGURE 1.1 BS EN 60617 symbols.

The four most commonly used diagrams are the block diagram, interconnection diagram, the circuit or schematic diagram and the wiring or connection diagram.

These diagrams indicate, by means of block symbols with suitable notes, the general way in which a system functions. They do not show detailed connections ().

In this case, items of equipment may be shown in block form but with details of how the items are connected together ().

These diagrams show how a system works, and need to pay no attention to the actual geographical layout of components or parts of components in that system. For example, a pair of contacts which form part of, say, a timer may appear in a different and quite remote part of the diagram than the timer operating coil that actuates them. In this case some form of cross-reference scheme is needed (e.g. T for the timer coil and T1, T2, T3, etc. for the associated contacts).

FIGURE 1.2 (a) Security system, (b) Intake arrangement for domestic installation.