BS 7671:2008 Requirements forElectrical Installations, IEE WiringRegulations 17th Edition was publishedin January this year. Installationsdesigned after the 30th June 2008 are tocomply with BS 7671:2008.The 17th Edition includes a newPart 7 (Special Locations), whichincludes new requirements forbathrooms. All those involved inelectrical installation work need to befamiliar with these new requirements.Help is at hand, in the form of a newedition of IEE Guidance Note 7(Special Locations), available soon.

Section 701, Locations containinga bath or showerScopeThe particular requirements of thissection apply to the electricalinstallations in locations containing a

fixed bath (bath tub) or shower and tothe surrounding zones as described inthe Wiring Regulations. TheRegulations do not apply to emergencyfacilities, e.g. emergency showers usedin industrial areas or laboratories. Forlocations containing a bath or showerfor medical treatment, specialrequirements may be necessary.

What’s new?Changes to the zonal system, RCDprotection on all bathroom circuits,230v socket outlets permitted 3 mhorizontally from the boundary ofzone 1; supplementary equipotentialbonding may be omitted subject to theRegulations being met.

The zonal systemThe Regulations state: Horizontal orinclined ceilings, walls with or

without windows, doors, floors andfixed partitions may be taken intoaccount where these effectively limitthe extent of locations containing abath or shower as well as their zones.This is similar to currentrequirements in the 16th Editionexcept that the actual locationcontaining the bath or shower ismentioned as well as the zones.The zones are similar to currentrequirements in the 16th Editionexcept for the omission of zone 3, alsothat zone 2 no longer extends abovezone 1.Zone 1 has been extended from 0.6 min the 16th Edition for showerswithout a basin for a fixed water outletto a distance of 1.20 m from the centrepoint of the water outlet. Demountableshower heads are no longermentioned.

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17TH EDITION LAUNCHEDSpecial Locations includes newrequirements for bathrooms by Geoff Cronshaw

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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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Zone 1 is now limited by thehorizontal plane corresponding to thehighest fixed shower head or wateroutlet or the horizontal plane lying2.25 m above the finished floor level,whichever is higher.

RCD ProtectionRegulation 701.411.3.3 now requiresthat additional protection shall beprovided for all circuits of the locationby the use of one or more RCDs havingthe characteristics specified inRegulation 415.1.1. This is a significantchange. Previously (601-09-02), onlyfixed current using equipment (otherthan electric showers) located in zone

1 required 30mA RCD protection andcurrent using equipment (other thanfixed current using equipment – suchas a washing machine, if suitable foruse in a bathroom, connected througha fused connection unit) in zone 3required 30mA RCD protection.Regulation 701.411.3.3 means that allcircuits, including lighting, electricshowers, heated towel rails, etc.,will require RCD protection, notexceeding 30 mA.

230 volt socket-outletsAnother significant change isintroduced by Regulation 701.512.3.This now permits 230v socket-outlets

2.25 m Outside zones

0.60 m

zone 0

Ceiling

Window recess

zone 2

zone 2

*

Outside zones

0.60 m

zone 2

Window recess

zone 2

zone 0

zone 1

Window recess

zone 2

Fixed water outlet

1.20 m

zone 1 zone 0

Figure 1: Zone dimensions -elevation view showing a bath tub

Figure 2: Zone dimensions -plan view showing a bath tub

Figure 3: Zone dimensions - plan viewshowing a shower without a basin

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to be installed in a room containing abath or shower providing they areinstalled 3 m horizontally from theboundary of zone 1. This changeresolves the ambiguity that existedbetween locations containing a bath orshower and a bedroom containing ashower.

Supplementary equipotential bondingRegulation 701.415.2 introduces afurther significant change regardingsupplementary equipotential bonding.The Regulation states that where thelocation containing a bath or showeris in a building with a protectiveequipotential bonding system inaccordance with Regulation 411.3.1.2,supplementary equipotentialbonding may be omitted whereall of the following conditionsare met:(i) All final circuits of the locationcomply with the requirements forautomatic disconnection according to411.3.2, and(ii) All final circuits of the locationhave additional protection by means ofan RCD in accordance 701.411.3.3, and(iii) All extraneous-conductive-parts ofthe location are effectively connectedto the protective equipotential bondingaccording to 411.3.1.2.This means the designer needs to

make an assessment that allextraneous-conductive-parts of thelocation are effectively connected tothe protective equipotential bondingaccording to 411.3.1.2.NOTE: The effectiveness of the

connection of extraneous-conductive-parts in the location to the mainearthing terminal may be assessed,where necessary, by the application ofRegulation 415.2.2.Regulation 415.2.2 states: Where

doubt exists regarding theeffectiveness of supplementaryequipotential bonding, it shall beconfirmed that the resistance Rbetween simultaneously accessibleexposed-conductive-parts andextraneous conductive-parts fulfils the

following condition:

R ≤ 50 V/Ia in a.c. systemsR ≤ 120 V/Ia in d.c. systemswhere

Ia is the operating current in amperesof the protective device for RCDs, IΔn,for overcurrent devices, the currentcausing automatic operation in 5 s.

External influencesThe Regulations state:Electrical equipment exposed to waterjets, e.g. for cleaning purposes, shallhave a degree of protection of at leastIPX5. The Regulations no longer limitthe IPX5 requirement to communalbaths or communal showers.There are no particular ingress

protection requirements beyondzone 2. This means that BS 1363accessories, such as switches andfused connection units, can beinstalled beyond zone 2, subject to therequirements of Regulation 512.2(external influences).

Current-using equipmentThe 16th Edition made a clear divisionbetween equipment permitted to beinstalled in zone 1 and equipmentpermitted to be installed in zone 2. Inthe 17th Edition no requirements arestated for zone 2. This is because allcircuits of the location now requireRCD protection.The term “current-using equipment

other than fixed current-usingequipment” no longer appears in the17th Edition.Current-using equipment, such as

washing machines and tumble dryersfor example, continue to be allowed tobe installed beyond zone 2, subject tomanufacturers’ approval similar to the16th Edition. Such equipment mustbe supplied by means of a fusedconnection unit within 3 mhorizontally from the boundary ofzone 1. Beyond 3 m they may besupplied by means of a plug andsocket-outlet.

Shaver supply unitsThe minimum degree of protection forequipment installed in zones 1 and 2 isIPX4 or IPX5 where water jets arelikely to be used for cleaning purposes.An exception to this requirement is ashaver supply unit complying withBS EN 60742 Chapter 2, Section 1,which, although it does not meet therequirements of IP4X, is permitted inzone 2 but must be located wheredirect spray from showers is unlikely.This type of shaver supply unit, whichincorporates a safety isolatingtransformer, is the only type which ispermitted in a bathroom or showerroom.

More information.For more information please refer tothe 17th Edition of the WiringRegulations. Also, help is at hand, inthe form of a new edition of IEEGuidance Note 7 (Special Locations)available soon. �

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