Best Practice Guide 5

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

Best Pracce 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 ContractorsAssociation 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 5The 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 manufacturersinstructions 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 separatebuilders 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

een

adja

cent

dw

ellin

gs)

Robu

stM

odifi

ed 3

0 m

ins*

*B,

C, b

ut A

can

be

just

ified

if tr

aditi

onal

con

stru

ctio

n co

nfirm

ed (

Ann

ex C

)Li

ghtw

eigh

tM

odifi

ed 3

0 m

ins*

*B,

CBe

low

room

ove

r gar

age

All

30 m

ins

B,

CO

ver b

asem

ent

All

30 m

ins

B, C

Roof

cei

ling

All

N/A

A (

assu

min

g ad

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ompa

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tion

betw

een

adja

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dw

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Fi

rst a

nd S

econ

d Fl

oor

All

30m

ins

B, C

Cei

ling

of g

arag

e un

der r

oom

A

ll30

min

s

Ove

r bas

emen

tA

ll30

min

sB,

C

Robu

stM

odifi

ed 3

0 m

ins*

*

Ligh

twei

ght

Mod

ified

30

min

s**

B, C

, but

A c

an b

e ju

stifi

ed if

trad

ition

al c

onst

ruct

ion

conf

irmed

(A

nnex

C)

Roof

cei

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All

N/A

(Ass

umin

g ad

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te c

ompa

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betw

een

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dw

ellin

gs)

All

Floo

rs, i

nclu

ding

gar

age

and

base

men

t cei

lings

/ flo

ors

All

60 m

ins

B, C

Flat

sTo

p flo

or

Documents

Best Practice Guide 5