The Design, Installation, Commissioning and Maintenance of Fire Detection and Fire Alarm Systems: A Guide to BS 5839-1

295 Pages·2008·3.56 MB·English

by  Colin S. Todd

The design, installation,
commissioning and
maintenance of fire
detection and fire
alarm systems
A guide to BS Code 5839-1
Colin S. Todd
First edition published by CMP Information Ltd in 2003
Second edition published by BSI in 2006
This new edition first published in 2008
by
BSI
389 Chiswick High Road
London W4 4AL
© British Standards Institution 2008
All rights reserved. Except as permitted under 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, photocopying, recording or otherwise
– without prior permission in writing from the publisher.
Whilst every care has been taken in developing and compiling this
publication, BSI accepts no liability for any loss or damage caused,
arising directly or indirectly in connection with reliance on its contents
except to the extent that such liability may not be excluded in law.
The right of Colin S. Todd to be identified as the author of this
Work has been asserted by him in accordance with sections 77
and 78 of the Copyright, Designs and Patents Act 1988.
Typeset in Century Schoolbook by Monolith
Printed in Great Britain by the MFK Group, Stevenage
British Library Cataloguing in Publication Data
A catalogue record for this book is available from the British Library
ISBN 978 0 580 63098 9
Foreword
This book follows on from two previous guides to BS 5839-1:2002 written
by Colin Todd and published in 2003 and 2006. Since publication of these
earlier guides, some amendments have been made to the code, while fire
safety legislation in Great Britain has been subject to radical change.
The advice provided by BS 5839-1:2002, the British Standard code of
practice for fire detection and fire alarm systems, is presented in the
form of explanatory information followed by specific recommendations.
The explanatory information helps readers to understand the rationale
behind the recommendations. This book serves to further that under-
standing. It is not a replacement for the code.
This guide not only explains the code, it also provides extensive
information regarding issues that have to be considered when designing,
installing and commissioning a fire detection and fire alarm system. It
could be considered as a course textbook for all those concerned with
fire detection and fire alarm systems, including users, regulators and
those who approve fire detection and fire alarm systems.
The guide benefits from the fact that Colin Todd was contracted by
BSI to produce the draft for the 2002 version of BS 5839-1. In preparing
that draft, Colin consulted various interested parties. It also benefits
from the fact that Colin is a member of the BSI technical subcommittee
(FSH/12/1), responsible for the code, and of its parent committee
FSH/12. He was involved in the committee discussions that took place
before the 2002 version of the code was published and in those before
each of the amendments to the code were made.
J.W. Northey
Chairman, BSI Technical Committees FSH/12 and FSH/12/1
xi
Contents
About the author ix
Foreword xi
1. Introduction 1
2. History of fire alarm installation codes 5
3. The format and layout of the code 23
4. Scope of BS 5839-1:2002 27
5. Contents of the code 33
6. Defining the terms 51
7. Selecting a suitable fire alarm system 59
8. The fire alarm contract and definition of
responsibilities 67
9. The interface between the fire alarm system
and other systems 71
10. The components of the system 77
11. Design of fire alarm circuits 81
12. Detection zones and alarm zones 99
13. Communication with the fire and rescue service 107
14. Audible, visual and tactile fire alarm signals 115
15. Staged fire alarms 131
16. Manual call points 137
17. Which type of detector? 143
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Design, installation, commissioning and maintenance
18. Spacing and siting of automatic fire detectors 159
19. Control and indicating equipment 177
20. Networked systems 183
21. Power supplies 187
22. Cables and wiring 203
23. Radio-linked systems 215
24. Electrical safety and electromagnetic compatibility 223
25. False alarms and their limitation 227
26. Installation work 257
27. Inspection and testing 263
28. Commissioning 267
29. Documentation 273
30. Certification 279
31. Acceptance by the user or purchaser 283
32. Verification 287
33. Routine testing 291
34. Servicing 295
35. Repair and non-routine attention 301
36. User responsibilities 307
viii
1. Introduction
The aim of this book is to provide guidance on the current version of
BS 5839-1, which was published at the end of 2002, with subsequent
amendments in 2004, and most recently, in April 2008. The code, which,
as one part of the BS 5839 suite of codes and standards, bears the generic
heading ‘Fire detection and fire alarm systems for buildings’, is entitled
‘Code of practice for system design, installation, commissioning and
maintenance’. As such, the code represents the universal ‘Bible’ for those
involved in the design, installation, commissioning, maintenance and
use of fire detection and fire alarm systems in the United Kingdom.
Compliance with the code is very commonly required by building
control bodies throughout the United Kingdom (although, in Scotland,
fire alarm systems are only required by the relevant building regulations
in specific occupancies), fire and rescue authorities and other authorities
who may enforce provisions for fire safety in certain occupancies (e.g.
housing authorities in the case of houses in multiple occupation, or
Health and Safety Executive for construction sites). Frequently, property
insurers also require automatic fire detection systems complying with
the recommendations of the code, or are prepared to take account of
such systems in their underwriting considerations, provided the system
complies with the code.
Consulting engineers also commonly demand compliance with the
code, often as part of the electrical specification for a building. However,
under the 2002 version of BS 5839-1, a simple reference to the code,
along with siting of devices on associated drawings, does not, by itself,
constitute design of the system, as that term is defined in the code.
Whereas, under previous versions of the code, there could be some
ambiguity as to whether some aspects of design were the responsibility
of the specifier, the supplier of the equipment, or the installer, the scope
and duties of the ‘designer’ under the 2002 version of the code are much
clearer, thereby, hopefully, resulting in less contract disputes if systems
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Design, installation, commissioning and maintenance
are found to fall short of compliance with the code. Experience shows,
nevertheless, that there is still an educational process required before
the identity and role of the ‘the designer’ is fully understood by all
relevant parties.
This guide is less detailed than the equivalent guide to the 1988
version of the code. The reason for this is that the 2002 version
now contains substantial explanatory text that provides background
information on the reason for the majority of the recommendations
made within the code. Moreover, the ‘unbundling’ of the explanatory
text and the recommendations within the code, effectively makes the
explanatory text, referred to in the code as ‘Commentary’, a form of
guide to the recommendations of the code. Although, inevitably, some of
the contents of this guide will virtually repeat parts of the commentary
within the code, the intention of this guide is not merely to pull together
such explanatory text into a single document. Instead, the guide is
intended to provide readers with guidance on practical application of
the recommendations in a variety of situations, taking into account the
insight to the recommendations provided by the commentary. Thus,
this guide is not a substitute for the code itself, but should be read in
conjunction with the code.
The guide should not be regarded as offering any final authoritative
interpretation on any recommendations of the code, although it is
hoped that the opinions expressed are an accurate reflection of the
relevant BSI technical committee’s intent when the code was published.
If it is essential to obtain a definitive interpretation, such as in the
event of a dispute, advice may be sought from BSI, which will refer the
matter to the relevant committee. Ultimately, the final arbiter in such a
dispute can, however, only be the courts. Hopefully, the 2002 version of
BS 5839-1 will be sufficiently less ambiguous and clearer than previous
versions that the need for such interpretations, and the occurrence of
disputes, will be uncommon. To further assist users in interpretation,
BSI intends, in the future, to publish a series of interpretations given in
response to queries put to the technical committee (rather like FAQs on
internet websites). This new information will be published as PD 6531,
most likely within the next two years.
In 2006, there were radical changes to fire safety legislation in Great
Britain, with greater responsibility placed on those who employ people
to work in, and/or have control over, buildings to ensure the adequacy
of fire precautions in the buildings for which they are responsible. More
specifically, suitable and sufficient fire risk assessments need to be
carried out by all such dutyholders.
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Introduction
There is a compelling logic in this approach to fire safety, and it has
already led to a much more flexible and pragmatic approach to the
formulation of appropriate ‘recipes’ for fire safety in buildings. There
is no doubt that this has led to enhanced recognition of automatic fire
detection as one of the ingredients in the recipe. Whereas, traditionally,
different components of fire protection were thought to be watertight
compartments, each considered separately and independently of the
others, the modern and more holistic approach to fire safety recognizes
the influence that the presence of automatic fire detection can have
on the level of safety afforded occupants of a building, sometimes
resulting in the possibility to relax requirements in respect of other
fire precautions. This recognition will be even more explicit after the
future publication of a new comprehensive guide to the design of fire
precautions in buildings, in the form of BS 9999.
This modern approach to fire safety is clearly acknowledged and
well recognized within BS 5839-1 (as amended). On this basis, it is
reasonable to assert that the 2002 version of the code constitutes an
important member of the suite of codes and standards on which fire
safety in the twenty-first century is based. Already, the original version
of the code has been subject to two amendments, necessitating this
third edition of this guide. These factors, coupled with the rate at which
fire detection technology advances, make it unlikely that the 2002 code
and this current edition of the guide will have the 14-year life of their
predecessors.
3
2. History of fire alarm installation codes
General
The earliest codes of practice for the installation of automatic fire
detection and alarm systems were those produced by the then Fire
Offices’ Committee (FOC). The ‘Committee’ comprised representatives
of most of the major fire insurers in the United Kingdom, and the
‘rules’ of the FOC were associated with fire insurance underwriting
considerations.
The FOC was constituted to represent fire insurers’ interests, after
insurers suffered numerous severe fire losses in the latter part of the
nineteenth century, particularly in London wharfs and warehouses.
Although the FOC became well known throughout the world as a fire
protection approvals and code producing body, its principal raison d’être
was to set minimum rates or ‘tariffs’ for different classes of trade.
Insurance premium discounts could be offered to clients who installed
adequate fire protection measures, whereas premium penalties could be
imposed for risks that had adverse features.
In order to ensure that the fire protection systems for which premium
discounts could be offered were reliable and effective, it was necessary
for the FOC to enter the business of approving equipment; the first heat
detector (known then as an ‘approved thermostat’) was approved around
the turn of the century. It was, however, also necessary to develop ‘rules’
for the installation of the fire protection equipment. Thus, the earliest
automatic fire detection codes of practice in the United Kingdom were
associated with protection of property, rather than safety of life.
Although simple, electrical, manual fire alarm systems became
well recognized as essential for protection of occupants of buildings,
it was to be many decades before automatic fire detection became
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Design, installation, commissioning and maintenance
recognized in the same light. Automatic detection tended to be regarded
as insufficiently reliable, or unnecessary, for protection of life. As
recently as the 1970s, guidance that supported the (now repealed) Fire
Precautions Act 1971, in respect of certification of hotels and boarding
houses under the Act, advised that a manual fire alarm system was
sufficient and that automatic fire detection might only be necessary to
compensate for shortcomings in structural fire protection measures,
such as means of escape. (Even today, it is, very occasionally, possible to
find a hotel or boarding house that has no, or very little, automatic fire
detection, having been certificated under the Fire Precautions Act in
the 1970s. However, such a situation would not meet the standards now
applicable in England and Wales under the Regulatory Reform (Fire
Safety) Order 2005*. Shortcomings in fire detection should be identified
by the fire risk assessment required by this legislation and should be
acted upon by the relevant dutyholder (normally the employer)).
1951 code: CP 327.404/402/501
The British Standards Institution (BSI) first produced a code of practice
(CP 327.404/402/501) in 1951. This code of practice was based on the
FOC rules and, indeed, reference to these rules, and more particularly,
the FOC list of approved equipment, was frequently made in situations
in which the role of the automatic fire detection system did relate to life
safety, rather than the property protection objective for which the rules
and the approved list were published.
1972 code: CP 1019
The FOC continued to publish their rules, and both these rules and the
BSI code appeared to stand the test of time, in that a new version of the
BSI code did not appear until 1972, when it was published as CP 1019.
Arguably, it was only then that the specialist nature of fire alarm systems
was recognized within BSI, in that, whereas CP 327 comprised a series
of codes of practice for telecommunications facilities, sound distribution,
clock systems and fire alarms, CP 1019 was a code of practice dedicated
to the installation and servicing of electrical fire alarm systems.
* and equivalent legislation in Scotland and Northern Ireland.
6