BG 70/2017 Life Safety and Firefighting Power Supplies SAMPLE

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A BSRIA Guide www.bsria.co.uk

Life Safety and Firefighting Power Supplies

By Tony Mayo SAMPLE

BG 70/2017 SAMPLE ACKNOWLEDGEMENTS

This publication was written by Tony Mayo of Hilson Moran and was designed and produced by Joanna Smith of BSRIA.

BSRIA would like to thank the following organisations and individuals for participating in the project:

Jeremy Hodge ACI Keith Elves BC Fire Safety Ltd. Chris May Cudd Bentley Nigel Clark Hilson Moran Ian Kershaw Hilson Moran Jeremy Smith Power Wise Systems (UK) Ltd. Steve Walsh Skanska Sam Grigg SPP Pumps

BSRIA would also like to thank the following organisations that kindly provided the photographs or diagrams which have made the illustrated guide possible:

ABB AEI Cables BSI E+I Engineering Ltd. Eland Cables Ltd. Fire Protection Ltd. Grundfos Pumps Ltd. GR Electrical Services Ltd. Hampshire Fire & Rescue Service LPA Connection Systems Prysmian Group Thorne & Derrick SAMPLEWEG (UK) Ltd.

The guidance given in this publication is correct to the best of BSRIA’s knowledge. However, BSRIA cannot guarantee that it is free of errors. Material in this publication does not constitute any warranty, endorsement or guarantee by BSRIA. Risk associated with the use of material from this publication is assumed entirely by the user. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means electronic or mechanical including photocopying, recording or otherwise without prior written permission of the publisher.

LIFE SAFETY AND FIREFIGHTING POWER SUPPLIES © BSRIA BG 70/2017

BG 70-2017 Life Safety Power Supplies 280217.indd 1 13/03/2017 17:05:41 DEFINITIONS

Supply Voltage The AC voltage definitions utilised within this guide are in accordance with BS EN 50160[48] and BS 7671[22]:

Extra Low Voltage (ELV) 50 V or less

Low Voltage (LV) 50 V to 1 kV

Medium Voltage (MV) 1 kV to 36 kV

High Voltage (HV) 36 kV to 150 kV

Extra High Voltage (EHV) more than 150 kV

Note that BS EN 50160 uses the term Low Voltage for anything below 1 kV and BS 7671 uses the term High Voltage for anything above 1 kV. Also, some documents, including BS 8519[29], use the terms Medium Voltage and High Voltage interchangeably.

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LIFE SAFETY AND FIREFIGHTING POWER SUPPLIES © BSRIA BG 70/2017

BG 70-2017 Life Safety Power Supplies 280217.indd 2 13/03/2017 16:22:59 PREFACE

The correct design, specification, installation and testing of life safety and firefighting installations are fundamental to protecting human life; both for the building occupants required to evacuate in the event of a fire and for the firefighters required to enter the building to deal with the incident. These systems depend on the integrity of their electrical supplies to operate when required to do so.

Many of the principal standards relating to the design of these critical building services power supplies are either currently under technical review, due for review shortly or have recently been republished following an update. The number of related standards continues to grow, as new European Standards are published and adopted in the UK, which can create fundamental conflicts between the various standards.

This guide has been prepared by the author to share the knowledge gained from working in the construction industry for almost 40 years and from his involvement with BSI on various related British Standard drafting committees. It has been compiled to assist those responsible for the design, installation, commissioning and maintenance of life safety and firefighting systems that are required to maintain their operation during a fire. These include sprinkler pumps, wet riser pumps, smoke control systems, firefighting lifts and escape lifts. The continuous operation of these systems, enabling the safe evacuation of the occupants and subsequent firefighting activities, is dependent on the security and integrity of their power supplies.

The aim was to produce a guide that will have a wide appeal to all those with an interest in the life safety and firefighting installations within buildings, including: • Designers (architects and engineers) • Installers (electrical contractors) • Manufacturers • Developers • Regulators • Owner-occupiers • Fire and rescue services SAMPLE• Third-party test houses This guide should also have an international appeal, where British Standards are recognised, such as in the Middle East and Europe.

Tony Mayo is a Chartered Electrical Engineer and has worked for Hilson Moran for 18 years, prior to which he worked for 22 years for a large M&E Contractor, Matthew Hall. He is a Fellow of the Institution of Engineering and Technology (IET) and the Chartered Institution of Building Services Engineers (CIBSE). He has been working with organisations such as BSI (British Standards Institution) and BCO (British Council of Offices) for close to 20 years.

LIFE SAFETY AND FIREFIGHTING POWER SUPPLIES © BSRIA BG 70/2017

BG 70-2017 Life Safety Power Supplies 280217.indd 3 13/03/2017 16:22:59 CONTENTS

1 INTRODUCTION 1 2 ELECTRICAL DISTRIBUTION 4 3 SECONDARY SOURCE OF SUPPLY 7 3.1 Life safety generator 7 3.2 Secondary utility supply 8

4 SWITCHGEAR REQUIREMENTS 10 4.1 ATS requirements 10 4.2 Motor control panels 12 4.3 Variable speed drives 12

5 CABLE DISTRIBUTION 14 6 CABLE SELECTION 16 6.1 Cable types 20 6.2 Cable support systems and fixings 22 6.3 Cable joints and junction boxes 28

7 FIRE-RESISTANT CABLE ENCLOSURES 30 8 FIRE-RESISTANT BUSBAR 37 9 LIFE SAFETY AND FIREFIGHTING APPLICATIONS 42 9.1 Sprinkler and wet riser pumps 42 9.2 Smoke control systems 57 9.3 Firefighting and evacuation lifts 59

APPENDIX A SUMMARY OF RELEVANT STANDARDS 61 APPENDIX B APPROVED CABLES INITIATIVE 71 APPENDIX C CONTAINMENT SIZING CALCULATION 72

SAMPLEREFERENCES 78

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INTRODUCTION 1

1 INTRODUCTION

Building Regulations in all parts of the UK include requirements concerning fire safety. These are supported by approved guidance, which is generally applicable to common building types. For more complex building types, the approved guidance refers to various parts of BS 5588[11], however these have all been superseded by BS 9999[35]. This guide therefore focuses on the large and/or complex buildings referred to in BS 9999, although the general principles are applicable to a much wider range of building types and applications.

This guide aims to draw together in a single document, the various power supply requirements outlined in many product and application specific standards. It also provides further detailed guidance on the specific applications, such as sprinkler and wet riser pumps, firefighting and escape lifts and smoke control systems, making reference to the appropriate standards. It identifies some of the key issues that should be considered by the electrical designer when locating the critical plant in the building and when selecting/specifying the appropriate switchgear and generators.

This guide is intended to give a clear understanding of the evolution of the many standards relating to life safety and firefighting equipment and their associated power supplies. It outlines the development of both British and European Standards, as well as other related documents, such as LPC Rules[1] TB210. It identifies where conflicts exist between documents and attempts to provide guidance on how they should be addressed.

Where fundamental inconsistencies exist between related standards, these are identified. This includes situations where one standard has been recently revised to incorporate latest best practice guidance or new recommendations originating from IEC or EN standards.

This guide not only refers to current and past standards, but also attempts to provide an indication of potential future developments of relevant standards currently under review in the UK and Europe.

This guide identifies the performance requirements demanded from the materials and products, including cables, cable enclosures, busbars and switchgear and describes the test methods used to assess their fire SAMPLEperformance and survival time under defined fire conditions. A logical format is used for this guide, covering the electrical installation from the source of supply, through switchgear, generators, automatic transfer switches (ATSs), and cable distribution to the life safety and firefighting equipment. Major components of life safety and firefighting equipment and their power supplies are illustrated in Figure 1, together with the standards applicable to these components and the sections of this guide where they are covered. A generic layout is indicated for a non- specific building. Note that the symbols used in Figure 1 are not the same as those used in Figures 2 and 3 or 34.

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CABLE SELECTION 6

Medium Voltage Cables When installing MV cables in a fire-resistant enclosure, it is important the designer/installer considers not only the thermal protection the enclosure offers the cable, but also the support and restraint the cable requires both in the horizontal and vertical routing of the cable. The cable should be secure under both normal and fault conditions.

The fire-resistant cable enclosures referred to in BS 8519 are generally intended to replace the need for cable tray or cable ladder to be installed and should therefore offer the equivalent level of support and restraint to the cables installed within the containment system.

The cable manufacturer’s technical literature should be consulted regarding the fixing centres required by the cable and its minimum bending radius.

The cable enclosure should incorporate suitable means to secure the appropriate cable cleats at the recommended fixing centres. The cable cleats are required to provide restraint against the electromechanical forces created under fault conditions.

The cable cleats selected for installation within the fire-resistant cable enclosure should be suitable for a minimum operating temperature of 250°C for the fire survival time of 2 hours.

The cable cleats selected should comply with the requirements of BS EN 61914[60].

Low Voltage Cables Enhanced fire-resistant cables should be secured in accordance with the cable manufacturer’s installation instructions in order to ensure the performance of the cable is not compromised under fire conditions by the cable’s own weight.

Figure 13: Cast iron cable cleats SAMPLE

Picture courtesy of Prysmian Group

The cable is required to be supported in such a way that it is not exposed to undue mechanical strain and so that there is no appreciable mechanical strain on the terminations.

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8 FIRE-RESISTANT BUSBAR

The test method requires the busbar configuration under test to be representative of the manufacturer’s recommended installation arrangement. The test specimen should include the manufacturer’s standard jointing materials, assembled strictly in accordance with manufacturer’s instructions. It should be secured within the furnace utilising the manufacturer’s recommended fixing assemblies, installed in accordance with their installation instructions.

Figure 27: Busbar sample being tested in a fire test furnace (based on BS 8602)

1 2

5 4

6 3

>500 Key 1. Firestopping 2. Furnace roof 5. Suspension device 3. Busbar trunking specimen 6. Joint 4. Fire-resistant tap-off unit (if applicable) 7. Furnace wall

Where the busbar is to be installed in a riser with tap-off boxes, they should be incorporated as part of the fire test assembly including a length of fire-resistant cable to simulate the feed from the tap-off unit.

A detailed description of the complete assembly should be included as part of the fire test report. Where the busbar components include the installation of supplementary fire-resistant material required to achieve the specified fire performance, these materials and their method of application SAMPLEshould be fully detailed in the fire test report. It is the responsibility of the designer to establish the extent of any de-rating required under normal operating conditions resulting from the application of the secondary material. A separate test report should be provided to cover the temperature rise performance of the material under normal ambient conditions.

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C CONTAINMENT SIZING CALCULATION

Option 1b: Non-life safety cables installed on one tray and life safety cables on a separate tray

Note that only the containment for the life safety cables is dealt with here. The sum of the diameters of the three cables is 108 mm, therefore a 150 mm cable tray should be used.

W = weight of cables per metre = 10.5 kg/m (summated from Table 14)

Lh = distance between hanger supports = 2 m (from Table 15)

WT = weight of 150 mm cable tray = 1.24 kg/m (from manufacturer’s data)

Wb = weight of bearers per metre = 2.88 kg/m (from Table 15)

Lb = length of bearer = 0.25 m (0.1 m longer than the width of the cable

Wr = weight of drop rods per metre = 0.6 kg/m h = height of drop rod = 1.5 m 2 ςmax = maximum allowable tensile stress = 10 N/mm

(10.5 × 2 + 1.24 × 2 + 2.88 × 0.25 + 0.6 × 1.5) × 9.81 2 A = = 12.3 mm 2 × 10

Minor diameter of threaded rod = 2 × √(12.3/π) = 4.0 mm

From the information in Table 16 on the previous page, the threaded rod with a minor diameter greater than 4.0 mm is M5. Therefore the minimum size of threaded rod required to support the non-life safety and life safety cables on a common cable tray in the above example under fire conditions for two hours would be two M5 rods per bearer, with the bearers at 2 metre centres.

Worked example 2 This second example is based on the reduced maximum tensile strength of 6 N/mm2 for a fire survival time of 2 hours quoted in BS EN 1366[6]. All other input data remains the same as in worked example 1.

Option 2a: Non-life safety and life safety cables installed on a single cable tray

(77.8 × 2 + 5.5 × 2 + 2.88 × 0.7 + 0.6 × 1.5) × 9.81 2 A = = 138.6 mm 2 × 6 SAMPLEMinor diameter of threaded rod = 2 × √(138.6/π) = 13.3 mm From the information in Table 16 above, the threaded rod with a minor diameter greater than 13.3 mm is M16. Therefore the minimum size of threaded rod required to support the non-life safety and life safety cables on a common cable tray in the above example under fire conditions for two hours would be two M16 rods per bearer, with the bearers at 2 metre centres.

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