Section 701 rules for rooms containing a bath or shower: the zones, 30 mA RCDs, IP ratings, SELV limits and when supplementary bonding may be omitted.
Why locations with a bath or shower are special
Section 701 of BS 7671 applies extra requirements because a wet body has reduced contact resistance, increasing the risk of electric shock. Distances from the water are divided into zones.
The zones
- Zone 0: for a bath or shower basin, the space inside it
- Zone 1: for a bath or shower basin, the space above Zone 0 to 2.25 m above the finished floor, or the highest fixed shower head or water outlet if higher
- Zone 2: for this bath or shower-basin arrangement, a 0.6 m band beyond Zone 1, with the same upper boundary
A shower without a basin has a floor-level Zone 0 reaching 100 mm above the finished floor. Its horizontal footprint matches Zone 1, which reaches 1.2 m from the centre of the fixed water outlet. There is no Zone 2 for that arrangement.
Check how walls, doors and fixed partitions limit the actual space. The area beneath a bath or shower basin is Zone 1 when it is accessible without a tool; that under-bath or under-basin space is outside the zones if access requires a tool. A cupboard label alone cannot settle an appliance’s zone.
Protection within the location
- low-voltage circuits serving the room need 30 mA RCD additional protection; this also applies to low-voltage circuits passing through Zones 1 or 2 without serving the room
- Zone 0 equipment needs at least IPX7 for temporary immersion. Zones 1 and 2 ordinarily need IPX4 for splashing; exposure to water jets calls for IPX5. Check the shaver-unit exception below
- equipment in Zone 0 must be suitable for that use, fixed and permanently connected, and supplied by SELV at no more than 12 V AC or 30 V ripple-free DC. Its safety source stays outside Zones 0, 1 and 2. An immersion rating does not permit a mains supply there
Socket-outlets
- Keep an ordinary 13 A socket at least two and a half metres from the outer edge of zone 1, measuring across the room. The zone 2 band beside a bath ends sooner; clearing that band or adding RCD protection does not remove the socket clearance.
- SELV socket-outlets and shaver supply units to the relevant standard may be installed closer
Omitting supplementary bonding
For a bathroom supplied by ordinary low-voltage circuits, local supplementary equipotential bonding may be omitted only when the installation has suitable main protective bonding and all these conditions hold:
- all circuits of the location have 30 mA RCD protection
- all extraneous-conductive-parts are connected to the main protective bonding of the installation
- all final circuits satisfy the required disconnection times
More bathroom details
- Zones are measured from the bath or shower, because that is where the wet-contact risk is.
- Equipment in zone 0, inside the bath, needs at least IPX7, the rating for temporary immersion.
- A shaver supply unit to BS EN 61558-2-5 may be fitted in zone 2 where direct shower spray is unlikely. Its isolating transformer separates the small-load output from the mains. A two-pin outlet marked BS 4573 describes the socket pattern; that mark alone does not establish that the complete unit has the required isolation. Check the supply unit, not just the plug shape.
- A pull-cord arrangement keeps its mains switching mechanism outside the zones. The insulating cord may enter Zones 1 or 2; height or being out of reach alone does not establish a permitted position.
- Electric floor heating in the room, unless supplied at SELV, needs an earthed metallic sheath or grid connected to the protective conductor.
- In England, every new circuit is notifiable under Part P. For additions or alterations to an existing circuit, check the defined special-location space: 0.6 m beyond a bath or tray, or 1.2 m from the wall or ceiling attachment of a shower head where there is no tray. The vertical limit is 2.25 m above the finished floor, raised to a higher attached shower head. A room containing a swimming pool or sauna heater also counts. Like-for-like replacement, repair and maintenance have a different notification position; inspection and testing still matter.
Other special locations
Each of these has its own requirements because the conditions raise the risk:
- swimming pools, for immersion, bare feet and large wet areas;
- saunas, for high temperatures;
- construction sites, where reduced low-voltage or battery tools cut the shock risk;
- farms and horticultural sites, with harsh conditions and animals;
- exhibitions and fairs, which are put up, moved and used by the public;
- medical locations, where patient contact makes a shock more serious.
Outdoor equipment needs an IP rating matched to rain, dust and splashing.