IET Wiring Matters | Winter 09

The IEE Wiring Regulations(BS 7671:2008) are based onEuropean Standards, which inturn are usually based oninternational standards. TheUK participates in bothEuropean and internationalstandards work.One new area of possible

development withininternational standards is anew section 7 providingrequirements for the suppliesto electric vehicles. Thisproposed new section 7 wouldonly apply to circuits intendedto supply electrical vehicles forcharging purposes and wouldcover the part of the electricalinstallation providing theconnection with an electricalvehicle to the fixed installation.

However, this is only a newwork item at this stage and it isimportant to point out that thismay not become aninternational standard. Thisarticle is based on draftproposals and, therefore, theactual requirements (if itbecame an internationalstandard) would probably bedifferent. Systems for thedistribution of electricity to the

public are outside the scope ofIEC 60364 low voltageelectrical installations (andalso outside the scope of BS 7671) therefore it isassumed that this new workitem applies to private suppliessuch as dwellings and privatecommercial and industrialestablishments.

The draft proposals mayinclude requirements for thetype and current rating ofsocket outlets, RCD protection,surge protection, measures ofprotection against electricshock, IP rating of equipment,impact protection againstmechanical damage, isolationand switching and fixingarrangements, etc.

Protection against electric shockIt is expected that theprotective measures ofobstacles, placing out of reach,non-conducting location andprotection by earth-free localequipotential bonding wouldnot be permitted.These measures are

contained in Sections 417 and418 of BS 7671:2008 and arenot for general application. The

Futuredevelopments in InternationalStandards for electricalinstallationsby Geoff Cronshaw

International Standards | 1

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2 | International Standards

Wiring Matters is produced by IET Services Limited, a subsidiary of The Institution of Engineering and Technology (IET), for the IET.Michael Faraday House, Six Hills Way, Stevenage, Herts, SG1 2AY, United Kingdom Tel: +44 (0)1438 313311 Fax: +44 (0)1438 313465

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Co-operating Organisations The Institution of Engineering & Technology acknowledges the contribution made by the following organisations in the preparation of this publication: British Electrotechnical & Allied Manufacturers Association Ltd – P D Galbraith, M H Mullins | Department for Communities and Local Government – I Drummond | Electrical Contractors Association – D Locke, S Burchell | City & Guilds of London Institute – H R Lovegrove | Electrical Contractors Association of ScotlandSELECT – D Millar, N McGuiness | Health & Safety Executive – K Morton | Electrical Safety Council | ERA Technology Limited – M Coates, A Finney | Consultant - M Al-Rufaie | Dept of Health - C Holme | British Cables Association – C Reed | Scottish Building Standards Agency | Department for Business, Enterpriseand Regulatory Reform | GAMBICA – M Hadley, A. Sedhev | Lighting Association – L Barling | ISSN 1749-978-X

Thank you to Schneider Electric for the image used on the Front Cover and page 16

protective measures of section417 provide basic protection onlyand are for application ininstallations controlled orsupervised by skilled or instructedpersons. The fault protectiveprovisions of Section 418 arespecial and, again, subject tocontrol and effective supervisionby skilled or instructed persons.

External influencesPresence of water (AD)Any wiring system or equipmentselected and installed must besuitable for its location and able to operate satisfactorily withoutdeterioration during its workinglife. The presence of water canoccur in several ways, e.g. rain,splashing, steam/humidity,condensation and at eachlocation where it is expected to bepresent its effects must beconsidered. Suitable protectionmust be provided, both duringconstruction and for thecompleted installation.For example, draft proposals for

a connection point installedoutdoors requires IPX4 in order toprotect against water splashes(AD4).The IP classification code,

BS EN 60529:2004, describes asystem for classifying the degreesof protection provided by theenclosures of electrical equipment.The degree of protection providedby an enclosure is indicated by twonumerals. The first numeral

Table 1 showing IPcharacteristic numerals

PWRRFP94

IET Wiring Matters | Winter 09

4 | International Standards

indicates protection of personsagainst access to hazardousparts inside enclosures orprotection of equipment againstingress of solid foreign objects.The second numeral indicatesprotection of equipment againstingress of water (see table 1).More information on the IPclassification code is given inIEE Guidance Note 1 -Selection and Erection.

External influencesImpact (AG)The effect of environmentalconditions and generalcharacteristics around aninstallation should always beassessed to enable suitableelectrical equipment to bespecified. All electricalequipment selected must besuitable for its location, use

and method of installation.Therefore, for equipment

installed in a car park site forexample, draft requirementsmay require IK07 or evenhigher such as IK10 if installedin a more vulnerable location.The IK classification

standard BS EN 62262describes a system forclassifying the degrees ofprotection provided byenclosures for electricalequipment against externalmechanical impacts. Theletters IK are followed by twonumerals which identify aspecific impact energy.BS EN 62262:2002

specifies a system forclassifying the degrees ofprotection provided byenclosures against mechanicalimpact (IK code).

The Standard describes onlythe general requirements anddesignations for the system.The application of the

system to a specific enclosuretype will be covered by theBritish Standard applicable tothat equipment or enclosure.An enclosure is defined as apart providing protection ofequipment against certainexternal influences andprotection against contact.This may be considered toinclude conduit, trunking, etc.In general, the degree of

protection will apply to acomplete enclosure. If parts ofan enclosure have differentdegrees of protection, theymust be separately identified.The coding is separate fromthe IP rating and will bemarked separately as shown in table 2.

Switchgear and controlgear.BS 7671:2008 (IEE WiringRegulations) recognises fourdistinct types of isolation andswitching operation:(i) isolation(ii) switching off for

mechanical maintenance(iii) emergency switching(iv) functional switching.

Draft proposals for supplies toelectric vehicles includerequirements for emergencyswitching. It is worth notingthat BS 7671:2008 states that

a plug and socket outlet orsimilar device shall not beselected as a device foremergency switching.

Socket-outletsDraft requirements for socketoutlets may include similarrequirements to caravan sites.For example, industrial type16A 200 V – 250 V sockets toIEC 60309-2, with an IP ratingof IP44, one socket outlet percar park space, 30 mA RCDprotection, and requirementsfor mounting heights, etc.Other requirements may

include visual indication ofmains supply, means ofisolation/emergency switching,interlock to prevent theplugging/unplugging of thesocket-outlet unless the socket-outlet has been isolated fromthe supply and precautions toprevent the electrical vehicle tosupply the fixed installation.

ConclusionMore and more electricalvehicles are on the market. Asa result this new work item hasbeen introduced in order todevelop the basicrequirements for theconnection of the electricalvehicle to the fixed installation.This article is only intended asa brief overview of a possiblenew work item which may ormay not be developed into aninternational standard. n

When higher impact energy is required the value of 50 joules is recommended

Table 2: IK characterisitics of BS EN 62262:2002