Special Locations
Separated extra low voltage (SELV) systems may be installed, but again these are difficult to achieve in practice, and need to be maintained and controlled by a competent person. Protected extra low voltage (PELV) systems are more common but again difficult to achieve in practice and must be properly designed and specified, so such systems are rarely utilized. The requirements of the 17th Edition of BS 7671 are not retrospective. This edition, however, now allows that supplementary equipotential bonding is not required in bathrooms provided that each circuit in the bathroom is provided with additional protection by an RCD sensitivity not exceeding 30 mA. This will be the preferred solution in new developments, but there are many existing dwellings and other locations with bath and shower facilities that already have supplementary equipotential bonding, and when bathrooms are modified or refurbished it may be more economic to extend or modify this rather than rewire and install RCDs.
G 2.4
Equipment selection and erection The equipment requirements of Section 701 are summarized in Table G 2.2, and the requirements fall into two types of regulation – ingress protection and suitability as regards switches and accessories.
Table G 2.2 Bathroom equipment selection and erection requirements. Requirement
Regulation
Equipment in Zone 0 shall be IP X7
701.512.2
Equipment in Zones 1 and 2 shall be IP X4
701.512.2
Equipment exposed to cleaning jets to be at least IP X5
701.512.2
In Zone 0, no switchgear or accessories allowed
701.512.3
In Zone 0, only 12 V current-using equipment complying with a relevant Standard is allowed
701.55
In Zone 1, only 12 V SELV switchgear or accessories allowed
701.512.3
In Zone 1, only whirlpool units, electric showers, shower pumps, ventilation equipment, towel rails, water heaters, luminaires and 25 V SELV or PELV equipment is allowed
701.55
In Zone 2, SELV switches and socket outlets and shaver supply socket outlets to BS EN 61558–2-5 are the only allowed switchgear or accessories
701.512.3
Notes
Particular requirements exist for IP and water jets; see D 16.2
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G