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Electricalinstallationsand theirimpact on thefire performanceof buildings:Part 1 - Domestic premises:Single family units(houses, flats, maisonettes,bungalows)

Best Prac�ce Guide 5

Electrical Safety First is indebted to the following organisationsfor their contribution and/or support to the development ofthis Guide:

Consultants to Electrical Safety First:

International Fire Consultants Ltdwww.intfire.com

This is one of a series of Best Practice Guides produced byElectrical Safety First* in association with leading industrybodies for the benefit of electrical contractors and installers,and their customers.

Association of Building Engineerswww.abe.org.uk

BEAMAwww.beama.org.uk

British Gypsumwww.british-gypsum.com

BSI Product Serviceswww.bsigroup.com

CEDIA UKwww.cedia.co.uk

Chief Fire Officers’ Associationwww.cfoa.org.uk

Electrical Contractors’ Associationwww.eca.co.uk

ELECSAwww.elecsa.org.uk

Institution of Engineering and Technologywww.theiet.org

Intumescent Fire Seals Associationwww.ifsa.org.uk

Knauf Drywallwww.knaufdrywall.co.uk

LABCwww.labc.co.uk

Lighting Associationwww.lightingassociation.com

Lighting Industry Federationwww.lif.co.uk

NAPITwww.napit.org.uk

NHBCwww.nhbc.co.uk

NICEICwww.niceic.com

SELECT (Electrical Contractors’Association of Scotland)www.select.org.uk

Tenmat Ltdwww.tenmat.com

Published by:

Electrical Safety First

Unit 331

Metal Box Factory

30 Great Guildford Street

London SE1 0HS

Tel: 0203 463 5100

Email: [email protected]

Website: www.electricalsafetyfirst.org.uk

Electrical Safety First and other contributors believe that the guidanceand information contained in this Best Practice Guide is correct, but allparties must rely on their own skill and judgement when making use ofit. Neither Electrical Safety First nor any contributor assumes any liabilityto anyone for any loss or damage caused by any error or omission in thisGuide, whether such error or omission is the result of negligence or anyother cause. Where reference is made to legislation, it is not to beconsidered as legal advice. Any and all such liability is disclaimed.

© Electrical Safety Council. March 2014

In electronic format, this Guide is intended to be made available free of

charge to all interested parties. Further copies may be downloaded from

the websites of some of the contributing organisations.

The version of this Guide on the Electrical Safety First website

(www.electricalsafetyfirst.org.uk) will always be the latest. Feedback on

any of the Best Practice Guides is always welcome – email

[email protected]

Electrical Safety First is supported by all sectors of the electrical industry,

approvals and research bodies, consumer interest organisations, the

electrical distribution industry, professional institutes and institutions,

regulatory bodies, trade and industry associations and federations, trade

unions, and local and central government.

*Electrical Safety First (formerly the National Inspection Council for

Electrical Installation Contracting) is a charitable non-profit making

organisation set up in 1956 to protect users of electricity against the

hazards of unsafe and unsound electrical installations.

©The Electrical Safety Council

1 Aim

1.1 The aim of this Guide is to promote best practiceby providing practical advice and guidance fordesigners, installers, verifiers and inspectors ofdomestic electrical installations where, as is oftenthe case, the electrical work requires, or hasrequired, the penetration of linings forming ceilingsand walls.

1.2 The guidance, which is intended to apply toelectrical installations designed after July 2008,may also be of benefit to specifiers, builders,building control bodies and other interested parties.

1.3 By following the guidance, it is considered thatelectrical installation work will not compromise thefire performance provisions that are mandatorilyrequired to be incorporated into domestic premisesunder the relevant building regulations.

2 Introduction

2.1 This Guide has been produced by Electrical SafetyFirst in association with the bodies indicated onpage 2.

2.2 It addresses the impact that electrical installationsin domestic premises have on the fire performanceof loadbearing and non-loadbearing walls and floors(and sometimes ceiling membranes) that have a firecontainment function, or are required to carry a loadfor a prescribed period.

2.3 Fire safety in buildings generally requires that in theevent of a fire:

• certain walls, floors and ceilings provide fireseparation for the purposes of constructing firecompartments and/or protected escape routes, and

• the structure resists collapse.

Electrical Installations andtheir impact on the fireperformance of buildings:

Part 1 - Domestic premises: Single family units

(houses, flats, maisonettes, bungalows)

Photo courtesy of Greater Manchester Fire & Rescue Service


2.4 The advice given in this Guide is aimed largely atpreserving the structural stability of the premises asmuch as the fire separation between areas. Forexample, in most domestic premises, it is theloadbearing capacity of the floors that isthreatened by early failure of ceiling linings, notthe fire separating function.

2.5 Many modern forms of engineered constructionhave an inherently lower level of fire resistancewhen compared to more traditional forms ofconstruction, and are heavily reliant on theplasterboard or similar linings for achieving therequisite level of fire separation.

2.6 Much of the guidance is related to the effect thatthe installation of electrical equipment will have onthe performance of the protective linings that areused to provide fire protection to lightweight joistedor studded constructions. In the case of theassociated wiring, the need to prevent fire frompassing through holes in all elements, whether solidor lightweight, is also addressed.

2.7 Amongst these forms of construction are narrowsection solid, stress graded timber joists,plywood/Orientated Strand Board (OSB) webbedI joists (‘timber I beams’), tooth or nail-platedtrusses and joists, composite timber studs andlightweight metal studs. Illustrations of thesevulnerable forms of construction are to be found inAnnex A.

2.8 The fire resistance of these elements can easily becompromised by inadequate fire sealing and'making good' after any penetration toaccommodate electrical equipment and associatedwiring.

2.9 Electrical equipment that has been identified ashaving a direct and significant influence on the fireperformance of buildings includes:

• flush-mounted consumer units

• concealed and recessed luminaires, includingdownlighters

• flush-mounted electrical socket-outlets, flex outletplates and data points

• flush-mounted switches, detection and controldevices

• recessed wall luminaires

• concealed speakers.

2.10 The above items all require the removal of a part ofthe ceiling or wall lining, and replacement with glass,thin metal or plastic that does not provide the samelevel of fire protection to the structural members,causing a reduction in the fire performance of theelement. These are known as partialpenetrations.

2.11 In addition to the influence that these partialpenetrations have on the fire performance, someinstallations can penetrate both linings, such as:

• associated wiring and conduits

• ventilation fans and related ductwork.

2.12 These installations have a potential to compromisethe fire containment capability, and guidance isincluded for these situations. These are known asfull penetrations.

2.13 In addition to the above items that all have a directinfluence on the fire performance of floors or walls,the following items can also have an indirectinfluence if the lining provides some or all of theirsupport:

• heavy ceiling-hung luminaires, lighting tracks andoverhead projectors

• wall-mounted brackets for televisions, heavyspeakers and flat screen installations.

If the room is involved in fire, the weight of suchitems may lead to the premature failure of thelining material.

Result of an eight minute fire on lightweight joists(Courtesy of Manchester City Council - Building Control)

2.14 In addition to the risk of the electrical installationreducing the fire separation capabilities of thoseelements that need to resist fire spread or to remainstructurally sound in a fire, a poorly constructedinstallation can potentially be the cause of a fire, forexample due to heat generated by looseconnections.

2.15 This Guide addresses all of these issues.

2.16 The fire separating capability of an element ofconstruction is generally measured by the durationfor which the element will satisfy the criteria of a fireresistance test. Historically, these criteria have beendetermined by exposure to the BS 476: Part 20:1987 heating and pressure conditions, but morerecently by the new European testing regime asembodied in BS EN 1363-1. More information onthe relevant test methods and criteria can be foundin Annex B.

3 Scope

3.1 This Guide gives practical advice and guidance forthe installation, and the making good following theinstallation, of electrical equipment and wiring inself-contained domestic premises (includingbungalows, multi-storey houses, individual flats andmaisonettes) that are designed to accommodate asingle family unit. The advice and guidance appliesto both new and existing premises.

3.2 The Guide does not apply directly to Houses inMultiple Occupation, hostels, caravans or boats, orto the communal parts of blocks of flats or thecommunal parts of maisonettes, nor does it apply toany premises used for purposes other than adwelling (such as small shops, factories or similarpremises used solely as places of work). Guidancefor these building types may be found in other Partsof this Best Practice Guide (in preparation).

3.3 The Guide gives advice on what needs to be doneto maintain the fire resistance of walls and ceilingsin domestic premises that have been penetrated orpartially penetrated in the process of installingelectrical equipment and wiring.

3.4 It does not consider in detail the impact that theinstallation of electrical equipment and wiring mayalso have on the structural, acoustic or energytargets prescribed in building regulations.

3.5 The Guide gives recommendations as to what isconsidered to be best practice, taking into accountthat electrical installers may not have adequateknowledge of the construction of the elements thatare potentially being compromised by their work.

3.6 Where an installer wishes to differentiate betweennew and traditional forms of construction, theguidance given in Annex C may assist. Someinvestigations may require the services of anotherprofessional, such as a surveyor or fire specialist.

Note: This Guide does not necessarily apply to all innovative or

unusual forms of construction or electrical equipment. If in

doubt, specialist advice should be sought.

page 5©The Electrical Safety Council


4 General electrical installation requirements

4.1 This Guide takes into account the publication ofBS 7671: 2008 (Requirements for ElectricalInstallations, IEE Wiring Regulations 17th Edition),which is the latest version of the national standardfor the safety of electrical installations, firstpublished in 1882.

4.2 BS 7671 requires, in Section 421 (Protection againstfire caused by electrical equipment), that equipmentmust not present a fire hazard to adjacentmaterials, and that manufacturers’ instructionsmust be complied with. Section 421 also requiresthat fixed equipment causing a concentration andfocusing of heat (such as spotlamps) shall be at asufficient distance from any fixed object or buildingelement so that the object or element is notsubjected to a dangerous temperature in normalconditions.

4.3 Also, in Section 527 (Selection and erection ofwiring systems to minimise the spread of fire) ofthat standard, it is required that wiring systems areselected and erected to minimise the spread of fire,including:

• Within a fire-segregated compartment, the risk ofthe spread of fire must be minimised by theselection of appropriate materials, and by theappropriate construction of the installation(Regulation 527.1.1), and

• A wiring system must be installed so that thegeneral building structural performance and firesafety performance are not reduced (Regulation527.1.2), and

• Where a wiring system passes through elements ofbuilding construction such as floors, walls, roofs,ceilings, partitions or cavity barriers, the openingsremaining after the passage of the wiring systemmust be sealed according to the degree of fireresistance (if any) prescribed for the respectiveelement of building construction beforepenetration (Regulation 527.2.1).

4.4 Regulation 510.2 requires manufacturers’instructions to be taken into account. It is importantto do this in order, for example, to preventluminaires becoming a source of ignition. (Anyinstallation instructions that are considered to beinappropriate should be queried with themanufacturer concerned, and amended installationinstructions requested.)

4.5 All terminations and joints, whether for low voltage(LV) or extra-low voltage (ELV) circuits, should beenclosed in accordance with Regulation 526.5 toprevent fire spread should a loose connection occur.

4.6. As part of the initial verification process, theelectrical installer has a duty to ensure that all thenecessary fire precautions have been taken,irrespective of which party was responsible for thatelement of the electrical work (Regulation611.3(vii)).


5 Legal

5.1 Building regulations for each part of the UK definefire performance objectives for the various elementsthat make up domestic premises, and giverecommended performance levels in guidancesupporting those regulations. The objectives aretaken into account in this Guide. For furtherinformation, see Annex D.

5.2 It is vital that the fire performance of critical wallsand floors is maintained to at least the levelrecommended in the guidance supporting theregulations, after the installation of electricalequipment and associated wiring.

5.3 For properties in England and Wales, attention isdrawn to the Party Wall Act. Under this Act, anywork undertaken on the party wall betweenproperties which could affect its performance (orindirectly affect the structure of an attachedneighbouring property) is a notifiable activity. InScotland, a building warrant is required for any workthat adversely affects a separating wall or aseparating floor.

5.4 The fitting of electrical equipment in a masonryparty wall has never been considered as beingnotifiable, but cutting holes in the linings andinstalling 'plastic' accessories may be deemed to becovered by statutory requirements. Electrical SafetyFirst therefore recommends that the neighbour beadvised of the intended work in order to give themthe opportunity to object to, comment upon, orprevent the work taking place.

5.5 Electrical installation work will often be undertakenon behalf of owners or tenants after the occupationof the premises and, as such, it is not subject to anyform of third party audit or final approval. Theelectrical installer is therefore subject to a duty ofcare to ensure that the fire performance of thepremises is not compromised. In Scotland, certainworks require building warrant approval dependingon the work proposed and the building type.

Note: In England & Wales, Part P of the Building Regulations

and, in Scotland, Building Standard 4.5, make this a

requirement, putting the responsibility on the installer if self-

certifying the work as compliant with building regulations.

Currently, electrical safety in Northern Ireland is not controlled

under building regulations.

RECOMMENDATIONS

6 Flush-mounted consumer units

6.1 Flush-mounted consumer units should not beinstalled in a fire separating wall. In exceptionalcircumstances, where this cannot be avoided, andsubject to the agreement of the Local Authority, theenclosure of the consumer unit or a separatebuilder’s work enclosure around the consumer unitmust provide a proven level of fire resistancecommensurate with the fire separating element.

Photos courtesy of Hager

Photo courtesy of MK


7 Downlighters(recessed luminaires)

7.1 When exposed to a fire from below, downlightersmay provide far less protection to a cavity and thestructural elements within it than the plasterboardthey are replacing, unless suitable precautions aretaken.

7.2 Electrical Safety First recommends that, whereverpossible, downlighters having integral fire protectionare selected for use in all ceilings where the liningthat is to be penetrated is the sole means ofkeeping fire and heat out of the cavity.

7.3 There are a number of types of downlighteravailable, and it is important that the type selectedfor a particular application has test evidence tosupport its fire performance when incorporated ina ceiling of the type into which it is to be installed.

7.4 Generally, the tests should have been carried out inaccordance with BS 476: Part 21: 1987 orBS EN 1365-2. The nature of the test evidence canbe critical, and is discussed in detail in Annex B.

7.5 Not all designs and styles of downlighter may beavailable with integral fire protection, especiallywhere higher lighting levels and/or larger coverage isrequired. In these situations, additional fireprotection may be fitted at the time of installationin the form of a 'fire hood', an insulated fire-protective box, or similar.

7.6 Such separate forms of protection must be fit forpurpose and not be easily dislodged or compromisedafter installation by subsequent work. Any suchprotection must conform to the guidance given inAnnex E.

7.7 Electrical Safety First recommends that downlightersinstalled in a ceiling beneath a roof space haveintegral fire protection, or are provided with someother suitable form of fire protection, in order tosafeguard escape from the premises, restrict thespread of fire, and reduce the risk of prematurefailure of the roof structure.

7.8. In order to avoid the risk of fire (as well as reducedlamp and service life) caused by overheating,downlighters and any associated transformers mustnot be covered by thermal insulation. BuildingRegulations do not prohibit the leaving of a smallarea around downlighters free from thermalinsulation where this is necessary to permit thedissipation of the heat they generate. However, dueallowance for this should be made in the overallthermal performance of the premises.

7.9 In all cases, manufacturers’ installation instructionsmust be followed to avoid downlighters becoming asource of fire.

7.10 Guidance on the selection of suitable types ofdownlighter for particular applications is given inTable 1, opposite.

Typical fire hood for a downlighter

Result of a downlighter fire(Courtesy of Manchester City Council - Building Control)

Typical downlighters with integral fire protection

(Photos courtesy of Safe and Sound Lighting Ltd)


Bui

ldin

gLo

cati

onC

onst

ruct

ion

Fire

Res

ista

nce

Req

uire

dR

ecom

men

ded

Bung

alow

Roof

cei

ling

All

N/A

A

Roof

cei

ling

All

N/A

A

(ass

umin

g ad

equa

te c

ompa

rtm

enta

tion

betw

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cent

dw

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gs)

Robu

stM

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*B,

C, b

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can

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stru

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Ann

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, B, C

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se

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ore)

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use

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le 1

: Rec

omm

enda

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for r

eces

sed

lum

inai

res/

dow

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s in

floo

rs a

nd c

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gs

**

= Se

e A

nnex

F

=

Robu

st c

onst

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is d

efin

ed in

Ann

ex C

=

Ensu

re th

at th

erm

al in

sula

tion

will

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ce lu

min

aire

=

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ld o

nly

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led

if it

can

be v

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at th

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netr

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e an

adv

erse

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ct o

n ac

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tic p

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ce

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twei

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ngin

eere

d co

nstr

uctio

n is

def

ined

in A

nnex

A

A =

Unp

rote

cted

dow

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per

mitt

ed, b

utsu

itabl

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e pr

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C =

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with

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NOTE

: In Sc

otland

, the

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nce clau

se 5.1.10 (D

omestic

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commen

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nlighters installed in th

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or are fitted

with

in th

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onda

ry ceilin

g.


8 Flush-mounted accessories (including switches, sockets, flex outlet

plates, data and telephone points etc)

8.1 Numerous flush-mounted accessories are commonin modern homes. These generally comprise twocomponents:

• a recessed housing, or back box

• a face plate with integral socket, switchmechanism, flex outlet etc, and associated wiringterminals.

8.2 Back boxes may be either moulded plastic or steelconstruction, but all designs incorporate large knock-out sections, many times greater in diameter thanthe cables passing through them, which make themvery permeable in a fire after the face plate has beendestroyed by the heat. This permeability will allowhot gases into the cavity of the wall much morerapidly than the plasterboard. For fire separatingapplications, and for applications relied upon to resistcollapse, this should be guarded against by providingadditional localised fire protection.

8.3 The risks associated with fire penetrating throughflush-mounted accessories are significant when theypenetrate a 30 minute fire-resisting loadbearingstud wall, 'back-to-back' with other accessories inthe same cavity (or interlinked cavities).

8.4 Therefore, where flush-mounted accessoriespenetrate each face of a 30 minute fire separatingor loadbearing plasterboard lined wall within thesame cavity space (that is, the gap between twostuds), each accessory should be fitted with a backbox that incorporates integral fire protection, or befitted with a proprietary fire protection pad, unlessevidence of the fire resistance performance of theaccessories is available.

Example of accessories being back-to back in the same cavity

space (can be at different heights)

Example of accessories not being back-to-back in the

same cavity

The effect of fire on a socket-outlet

(Photo courtesy of Greater Manchester Fire & Rescue Service)

Photo courtesy of Greater Manchester Fire & Rescue Service

Plan view

Plan view


8.5 Such back boxes or protective pads must haveevidence of performance to demonstrate that theyhave the ability to maintain the fire separationcapability of a wall for 30 minutes, were they to betested to BS 476: Part 21: 1987 (loadbearing) orBS 476: Part 22 (non-loadbearing), or the ENequivalent as appropriate (see Annex B), with plasticaccessories fitted in both linings.

Fire protection pad fitted externally

The box depth must be selected so that with the pad in place,the required clearance is maintained between the pad and theaccessory, and the wiring is not unduly distorted.

8.6 Recommendations for the protection of flush-mounted accessories in timber or metal stud walls inparticular situations are given in Table 2 (on thefollowing page).

!

Fire and acoustic rated cover fitted behind a dry lining box(Photo courtesy of Tenmat Ltd)

Intumescent pad being installed in a dry lining box(Photo courtesy of Knauf Drywall)

Intumescent insert being installed in a dry lining box(Photo courtesy of Tenmat Ltd)

Plan view

Plan view


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to-b

ack

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lini

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ings

#

KEY:

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rey

(or m

ore)

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use

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l sep

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gara

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om o

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s

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l sep

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gara

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room

sFo

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y pl

us

hous

e (a

ttac

hed)

Dup

lex

flats

Thre

e-st

orey

hou

se

(att

ache

d)

60 m

in

Fitin

g in

one

or b

oth

linin

gs #

Wal

l sep

arat

ing

gara

ge fr

om o

ther

room

s

Tabl

e 2:

Rec

omm

enda

tions

for f

lush

-mou

nted

acc

esso

ries

in ti

mbe

r and

met

al s

tud

wal

ls

Sepa

ratin

g w

all b

etw

een

dwel

lings

#

Thre

e-st

orey

hou

se

Stai

rway

enc

losu

re

Two-

stor

ey h

ouse

(a

ttac

hed)

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l sep

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om o

ther

room

s

Fitt

ing

in o

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ings

#

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ack-

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lini

ng o

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lini

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B

Wal

l sep

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gara

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om o

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s

Inte

rnal

sta

irway

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losu

re

B B B

NOTE

: In Sc

otland

, the

guida

nce clau

se 2.2.7 (D

omestic

Han

dboo

k) re

commen

ds th

at com

bustible sep

arating walls do no

t con

tain pipes, w

ires or other service

s. In bu

ildings

with

a storey he

ight

over 18 m, sep

arating walls and

floo

rs m

ust b

e co

nstruc

ted of non

-com

bustible m

aterials.


9 Flush-mounted wall luminairesand concealed speakers in walls or ceilings

9.1 This type of equipment varies significantly in size,design and construction. It is therefore not possibleto give specific advice in this Guide in respect of thebest method of maintaining the fire performance ofthe lining(s) penetrated by such equipment.

9.2 In principle, however, speakers concealed in ceilinglinings should be treated by analogy withdownlighters, and both luminaires and speakersflush-mounted in walls should conform to theguidance given for flush-mounted accessories.

9.3 Where a luminaire or speaker has integral fireprotection, then this must be to the appropriate teststandard (see Annex B).

9.4 If the equipment does not have integral fireprotection then, when it is being installed in a ceilingor wall that is required to provide fire separation, theequipment has to be provided with an ad hoc formof fire protection and, where appropriate, acousticinsulation. It may be difficult for the installer toestablish what form of protection is likely tomaintain the required fire resistance, and thereforeany proposed method of providing protectionshould be tested, or more reasonably assessed inlieu of test evidence, by those authorities recognisedin guidance in support of regulations*.

9.5 Proprietary protection is likely to become available indue course, and should be used when it does.

* Approved Document B for the Building Regulations for England

& Wales (A1 of Annex A), or the Scottish Building Standards

Technical Handbook, as appropriate

10 Cables, conduit and trunking penetrating internal fire separating walls and floors

10.1 This section provides guidance as to what should bedone to preserve the fire resistance of elements thatare required to provide fire resistance, when cableshave to pass through them. The guidance isapplicable to situations where insulated andsheathed cables, or cables in plastic conduit orplastic trunking, pass through floors and walls.

10.2 The fire risk associated with non-fire performancecables and plastic conduits and trunking passingthrough building elements is twofold. Initially thereis a risk of a loss of integrity due to the heat and/orflames passing through any unsealed holes thathave been made to allow the cable to pass through,resulting in flaming on the unexposed side.Secondly, the hole in a plasterboard lining will allowfire to get into the ceiling or wall void prematurely,cause ignition of the structure which can lead to aloss of loadbearing capacity.

10.3 With respect to the first of these, it is important thatfire is not allowed to exploit either the initialpenetration of the first lining (which could permitfire to get into the cavity), or subsequently topenetrate the second lining (which would allow thefire to effectively bypass the protective barrier).

10.4 Sealing the cable ingress point has to take intoaccount that the insulation of non-fire performancecables will probably melt or char away, leaving anunfilled gap between the conductors and the lining.Depending upon the nature of the cable insulation,this may even have the potential to carry the flameson its surface into the void. On a single cable this isunlikely to be a serious risk, but the ability to makean adequate fire seal becomes increasingly difficultas the number of cables increase.

Photo courtesy of CEDIA/Smartcomm

Fire seals around cables and trunking


10.5 It is common and accepted practice to make goodany hole around a cable by using inert filler such asplaster or grout, but this does not compensate formelting/flaming insulation, and will also beineffective in voids between cables.

10.6 It is recommended, therefore, that the sealant usedto make good holes through which cables pass hasintumescent properties: that is, it has the ability toexpand and fill any voids that are developing due tomovement and/or melting of cables, in order tomaintain the fire resistance of the element.

10.7 The risk of fire gaining premature access to any voidis increased if the cables are run through a plasticconduit or trunking system, or are bunched. Anycosmetic sealing of the gap between the lining andthe plastic conduit or trunking will certainly not beable to seal any voids between the cables and theouter plastic casing following the melting of theconduit or trunking.

10.8 In elements that require high levels of fireresistance, especially where there is a sleeping risk(such as 60 minute compartment walls and floors),it is recommended that a proprietary cable transit ora fire resisting conduit be installed in theconstruction element being penetrated, if serviceshave to pass through one or both linings that formthe wall.

NOTE: In Scotland, the guidance clause 2.2.7 (Domestic

Handbook) recommends that combustible separating walls do

not contain pipes, wires or other services. In buildings with a

storey height over 18 m, separating walls and floors must be

constructed of non-combustible materials.

11 Ventilation fans and related ductwork

11.1 Ventilation fans are normally fitted on an externalwall rather than on an internal wall and, as aconsequence, there is generally not a fire safetyissue regarding the influence on the integrity andinsulation rating of the wall due to such systemswhen installed in a cavity blockwork or masonry wall.

11.2 However, if fire were to enter the cavity of a studwall or the cavity between the inner wall and anyouter 'sheathing', the building can suffer bothundue structural damage if modern engineeredconstruction is used, and/or disproportionate firespread in the cavity in more conventional properties.This cavity spread can result in an indirect loss of fireintegrity between adjacent internal enclosures, andtherefore fire should be prevented from gainingaccess to any of the cavities.

11.3 When installing a ventilation fan directly into aloadbearing external stud construction wall, the holecut into the inner and outer lining should be linedout across the thickness of the wall with acontinuous non-combustible material, preferablywith some insulating properties, through which theextract duct passes**. This liner should be fixed inplace so that it does not fall away over time.

11.4 When the vent from for example, a shower cubicle,is connected to an extended duct which runs withinthe floor void to an outside wall possibly via an in-linefan, then this length of low melting point ductwork(plastic or aluminium) will have no measurable fireresistance and fire entering into this duct, via thevent, will soon have access to the joists. Indeed,should the fan be in extract mode at the time of thefire, fire will be drawn into this void quite quickly

** This liner may, for example, consist of plasterboard tightly fitted at the corners and held in place by silicone sealant or the duct may be wrapped in a suitable intumescent-based liner.

Fire spread into bathroom via plastic duct(Photo courtesy of Greater Manchester Fire & Rescue Service)


11.5 Any void between two joists that contain such a ductwhich is running parallel with the joists should belined on the face of both joists with fire protectionboard that duplicates the fire protection provided bythe ceiling lining. The void beyond the duct shouldbe separated by a transverse barrier of the samerating. Similarly, the flooring above may need to beunderdrawn with fire protection board if it is butt-jointed. The method of fire sealing the wall/ductinterface will vary depending upon whether it is astudded construction or a conventional masonrycavity wall (see Figures 11a and 11b).

11.6 Where the duct runs transverse to the joists, theamount of joist to be cut away is likely to bestructurally significant and expert guidance shouldbe sought, in respect of both the effect on thestructure and the fire separation measures.

Figure 11a: Joist/wall protection when installing vent into conventional masonry wall construction

Figure 11b: Joist/wall protection when installing vent into timber frame wall construction


12 Wall or ceiling-mounted electrical equipment

12.1 It has become increasingly common to mountheavy equipment such as TVs, speakers, flat screeninstallations etc on wall brackets, and to hang heavyluminaires, lighting track and projectors etc from theceiling.

12.2 Plasterboard linings are not designed to carry suchweights under fire conditions and, unless theseitems are fixed back only to the structural membersin the wall or floor, they will pull down the liningsonce the board is weakened by the fire.

12.3 Weakening of normal and 'sound' gradeplasterboard will occur rapidly after fire hasconsumed the room face paper lining and, whilstfibreglass-reinforced board will not fail quite asquickly or as dramatically, fixings will pull through itat a fairly early stage in the fire attack.

12.4 Obviously, early failure of these protective linings willallow fire attack on the studs and joists which again,if of engineered construction (see Annex A) will leadto premature structural failure.

12.5 All heavy equipment mounted on the face of wallsor hung from the ceiling must be supportedcompletely independently from the fire protectiveplasterboard linings. Whilst it may be permitted tofix directly to the joists, false ceiling members orstuds, none of the fixings should rely solely onplasterboard.

12.6 If any additional fixings are needed beyond thosethat the structure is able to provide, then a sectionof the lining should be completely removed and theedges of the 'hole' fitted with supports to which'both' edges of the plaster board can be fixed.

12.7 Additional structural members should then be fittedbetween joists and studs at the required fixinglocations and the new plasterboard should bescribed, cut to size/shape and fixed in accordancewith plasterboard manufacturers’ instructions,before fitting the suspended equipment. Jointsbetween existing and new plasterboard liningsshould be filled and skimmed with plaster.

Photo courtesy of CEDIA/Smartcomm


ANNEX A

Examples of forms of modernengineered construction coveredby this Guide.

Floor Joists

Timber 'I' beams; consisting of Orientated Strand Board (OSB)

or plywood webs with solid timber or laminated timber top and

bottom chords.

Steel webbed, timber 'I' beams; consisting of corrugated steel

webs with timber top and bottom chords

Punched metal plate connected 'truss' joists

Space joists; consisting of timber top and bottom chords spaced

apart by pressed steel 'boomerangs'

Narrow stress graded softwood joints (less than 38mm)

Studs

Glue laminated 'timber' studs

Steel 'C' studs

Narrow stress graded softwood studs (less than 38 mm)


ANNEX B

Under regulatory guidance there are a number of firetests called up against which the elements, togetherwith installed components as they will be in practice,have to be verified. The ability of the element tosatisfy the structural fire requirements and fireseparating objectives is adjudged by a series ofestablished British and European test procedures.

The relevant standards are:

• Non-loadbearing walls and ceiling membranes:BS 476: Part 22: 1987, or BS EN 1364: Parts 1 and 2.

• Loadbearing walls and floors; BS 476: Part 21: 1987,or BS EN 1365: Parts 1 and 2.

• Wires, cables and conduit penetrating elements;BS EN 1366-3.

• Suspended ceilings that are provided only for theprotection of steel beams*; BS 476: Part 23: 1987.Note there is no directly comparable BS EN test forthis purpose.

In respect of these tests, the criteria of failure areloadbearing capacity (BS 476 Part 21 and BS EN 1365only), integrity and insulation, which are defined asfollows:

Loadbearing capacity is the ability to carry the designloads for the specified period without collapse orexceeding pre-determined deflection limits.

Integrity is the ability to resist the passage of flames, orthe passage of critically hot gases (measured by means ofan oven dry cotton pad).

Insulation is the ability to restrict temperature rise on theunexposed face to a mean temperature rise of 140 oCand a maximum temperature rise of 180 oC.

*The use of a suspended ceiling provided for the purpose ofprotecting steel beams in lieu of cladding, or spraying them, is a

very restricted application and will rarely be found in the

domestic sector. Unfortunately, a number of proprietary

products available for protecting downlighters will have

erroneously been tested to this standard, but these will not be

suitable for ‘making good’ fixed ceilings or suspended ceilings

used to provide protection to 'timber' joisted floors or other

'domestic' forms of construction.

Floor above in danger of collapse (Photo courtesy of GreaterManchester Fire & Rescue Service)


ANNEX C

Guidance on what constitutes robust constructionwhich identifies where unprotected downlighters maybe fitted

When the installer wishes to fit unprotected**downlighters, it is necessary to establish the constructionin detail and ensure that the floor is of one of thefollowing constructions;

a) First floor of two-storey house:

• the joists are solid timber not less than 43 mm thickand at no more than 450 mm centres, and

• the floorboards above are either tongue andgrooved softwood greater than 18 mm thick or aretight fitting butt jointed softwood boards free fromdead knots, or is 'timber' based jointed flooring notless than 18 mm thick, and

• the ceiling consists of 12.5 mm plasterboard or'sound' lath and plaster with the ‘hooks' in goodcondition.

If downlighters are installed in a compartment floor (orseparating floor in Scotland – see Annex F), they must beprotected** regardless of the construction.

b) All other floors in a single family unit:

• As for the first floor above, except butt jointed floorboards are not permitted without an overlay ofmedium density fibreboard (MDF), hardboard orplywood not less than 4 mm thick.

c) One hour fire resisting floors between flats:

• the joists are solid timber not less than 43 mm thickand at no more than 450 mm centres, and

• the floorboards above are either tongue andgrooved softwood boards greater than 18 mm thickand free from dead knots, or is ‘timber’ basedjointed flooring of a similar minimum thickness

• the ceiling consists of two layers of plasterboard, notless than 30 mm1 thick for non-fire rated board ornot less than 25 mm thick of fire rated 1 & 2 board.

**Protected means downlighters that incorporate integral fire protection or which are fitted with fire hoods that comply with theguidance given in Annex E of this Guide.1 Excluding any textured surface which should be removed locally prior to fitting the luminaire2 Type 5 to BS 1230 or Type F to BS EN 520


ANNEX D

Summary of the recommendations given in nationalregulatory fire safety guidance:

The requirements given in Table 1 and 2 of this Guide arethe 'recommendations' made in the Guidance Documentpublished in support of the relevant regional regulations.These Guidance Documents offer a prescriptive solutionto the 'functionally' expressed regulations in the relevantregion of the UK. At the time of publication, the relevantregional regulations that deal with the fire safety issuesare:

England & Wales

The Building Regulations 2000

• Approved Document B

- Fire Safety (Volume 1)

- Dwellinghouses (2006 Edition)

Scotland

The Building (Scotland) Regulations 2004

• The Scottish Building Standards Technical HandbookDomestic (2007)

Northern Ireland

The Building Regulations (Northern Ireland) 2000,as amended

• Technical Booklet E, 2005

The above regulations apply only to new build, or tomajor refurbishments (material alterations) that arenotified after the dates given. Buildings alreadyconstructed and/or occupied will have complied with theregulations and associated guidance in force at the timeof application.

These Guidance Documents would have expressed therecommended fire performance of the structure in termsof the test standards described in Annex B


ANNEX E

Test procedure to evaluate the robustness ofdownlighter fire hoods

1. INTRODUCTION

This Annex provides requirements1 that need to besatisfied by a downlighter fire hood that isconsidered to be 'robust' in both its constructionand fitting, and thereby meets therecommendations given in this Guide.

During installation, in order not to compromise theperformance of the downlighter, it is essential thatthe area immediately above the downlighter andthe fire hood remains free from thermal insulation(see 7.9). Subsequent to its installation, however,the fire hood needs to demonstrate its ability toremain in place and resist crushing, that is to be'robust' in the event of any application of thermalinsulation or other material by others.

2. SCOPE

The purpose of this test procedure is to assess theability of a downlighter fire hood which has satisfiedthe fire test requirements of BS 476: Part 21: 1987to retain its mechanical stability over its working lifewhilst providing the requisite level of fire protectionto the structure of the buiding from a downlighterlocated beneath.

3. TEST PROTOCOL

The test protocol is a two part test.The first partdeals with the ability of the specimen fire hood toresist compression after the application of theinsulation within the test frame. The second partdeals with the ability of the fire hood to resistdislodgement subsequent to installation.

4. TEST EQUIPMENT

The test assembly is designed to simulate adomestic ceiling. It consists of two softwood floorjoists 225 mm x 47 mm x 1500 mm long held450 mm apart, being screwed to similar sectionedtimbers at either end.

The base of the test construction consists of a singlesheet of 12.5 mm type plasterboard nailed to theunderside of the timber framework. Two furthersheets of 12.5 mm plasterboard 1500 mm x300 mm are screwed to the inner face of the twomajor timber sections in a vertical position.

Midway down the length of the frame, a hole is cutin the centre of the plasterboard on the undersideof the test frame. The size of the hole so cut shouldbe equal to that formed in the ceiling toaccommodate the downlighter that the fire hood isdesigned to protect.

A 1400 mm length of 400 mm wide mineral wool(24 kg/m3) is cut sufficient to provide an overallinsulation depth of 270 mm within the test frame.The test assembly is held in position 2 m aboveground level by the use of appropriate scaffolding.

5. TEST PROCEDURE

5.1 Compression test

The specimen fire hood is located above the hole inthe manner prescribed by the manufacturer. Unlessthe device is identified as being suitable only forinstallation from above, this will be positioned frombelow.

Once the specimen has been located in position, thedistance between the top innermost part of the firehood and the lower surface of the plasterboard ofthe main structure shall be measured in at least 3places, averaged and noted (a).

1These test requirements have been developed by IFSA, the Intumescent Fire Seals Association. IFSA is a recognized trade associationfor manufacturers of intumescent materials and intumescent-based systems, membership of which requires all product claims to besubstantiated.


Once this has been ascertained, the insulationdescribed above is laid down the length of the testrig so as to be resting on the upper surface of theplasterboard and specimen.

At this point, the distance referred to above will bemeasured again (b). The insulation shall remain inplace for 25 days. After this period, the distancereferred to above will be measured once more (c).

Once the above distances have been ascertained,the insulation should be removed and the‘dislodgement test’ should be undertaken on thesame test specimen

5.2. Dislodgement test

One end of the test assembly will remain supportedvia a 'hinge', whilst the opposing end isprogressively raised or lowered at a rate of100 mm/sec until either:-

a) the specimen fire hood becomes dislodged, in excess of the permitted amount or

b) the test assembly reaches an angle of45 degrees.

6. PERFORMANCE CRITERIA

6.1. Compression test

In the case of the second measurement (b), areduction in the average distance of less than 5%,or 5 mm (whichever is the smaller) is acceptable.For any reduction in excess of this figure, thespecimen is deemed to have failed. In the case ofthe third measurement (c), there should be nofurther reduction in distance measured.

6.2. Dislodgement test.

If the specimen moves laterally by more than10 mm or a gap of 3 mm appears between thespecimen and the top surface of the plasterboardprior to, or on completion of, the movement test,then the specimen will be deemed to have failed.

ANNEX F

Glossary of terms

Luminaire – equipment which distributes, filters ortransforms the light transmitted by one or more lamps,and which includes all the parts necessary for supporting,fixing and protecting the lamps, but not the lampsthemselves and, where necessary, circuit auxiliariestogether with the means for connecting them to thesupply.

Critical application – An application where theconsequences of a failure to provide the fire resistancerequirements for an element will have a direct impact onthe life safety of the occupants, e.g. between adjacentdwellings.

Compartment wall/floor – known in Scotland asseparating wall/floor.

‘Modified’ fire resistance – In domestic applications thefire resistance of the first floor has a loadbearing capacityof 30 minutes, but the integrity and insulation criteria arereduced (modified) to only 15 minutes.

House in Multiple Occupation - For England and Wales,the legal definition of a House in Multiple Occupation isto be found in Sections 254-260 and Schedule 14 of theHousing Act 2004 or, in the case of Scotland, the CivicGovernment (Scotland) Act 1982 (Licensing of Houses inMultiple Occupation) Order 2000 as amended.

‘Separating floor and wall’means in Scotland a floor orwall constructed to prevent the spread of fire betweenbuildings or parts of buildings of separate habitation, suchas flats and maisonettes.

Three-storey house: A house in single occupation withtwo floors above ground floor levels, often referred to as atown house.

House of four storeys, or more: A house that has threeor more floors above ground floor where the height of theuppermost floor does not exceed 18 m.

page 23©The Electrical Safety Council

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