Bathroom zones under BS 7671

The Wiring Regulations divide a room containing a bath or shower into zones, so that the rules for what can be installed where are specific and measurable. Equipment is either inside a zone or outside it, and a tape measure settles any argument.

The zones

• Zone 0 is the inside of the bath or shower tray. Only equipment specifically designed for it, at 12 V or less, is permitted.
• Zone 1 is the space directly above the bath or shower tray, up to the height of the highest fixed shower head or water outlet, or 2.25 m above the finished floor, whichever is higher. For a shower without a tray, zone 1 extends 1.2 m from the centre of the fixed water outlet.
• Zone 2 is the area 0.6 m beyond the edge of zone 1, to the same height.

Walls, doors, fixed partitions and ceilings can limit the zones where they genuinely stop water reaching the other side. Outside zone 2 there are no special ingress requirements beyond the general rule that equipment must suit its location, so switches and fused connection units are allowed there.

Protection in the zones

Equipment in zones 1 and 2 must be at least IPX4, or IPX5 where water jets are used for cleaning. The one exception is a shaver supply unit to BS EN 61558-2-5, which is allowed in zone 2 where direct spray is unlikely, and is the only type of shaver socket permitted in a bathroom.

RCD protection for every circuit

Regulation 701.411.3.3 requires additional protection by a 30 mA RCD for all circuits of the location. Lighting, electric showers, heated towel rails, underfloor heating and extractor fans are all included. This was introduced in the 17th Edition in 2008 and is one of the most common reasons an older installation fails an EICR.

Socket outlets

A 230 V socket is only permitted if it is at least 2.5 m horizontally from the boundary of zone 1 (Regulation 701.512.3; the 17th Edition said 3 m). For most bathrooms that means no sockets at all.

Appliances in the bathroom

Fixed appliances such as washing machines and tumble dryers may be installed only if they are supplied from a switched fused connection unit outside the zones, protected by a 30 mA RCD, and the manufacturer permits installation in a bathroom (Regulation 701.55).

Supplementary bonding

Older bathrooms have green and yellow bonding conductors linking the pipes, the bath and the radiator. Under Regulation 701.415.2 that supplementary bonding can be omitted where all three conditions are met: every circuit in the room meets the disconnection times in Regulation 411.3.2, every circuit has 30 mA RCD protection, and all extraneous metalwork is effectively connected to the main protective bonding. That assessment has to be made and recorded by the electrician; it is not a reason to cut existing bonding out without checking.