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Having electrical wiring in a bathroom can be tricky to set up, as there are important regulations to follow. In order to ensure a safe and legal installation, it is essential to understand the rules and regulations around the layout of electrical equipment in bathrooms. This article will provide an overview of the bathroom zones for electrical wiring regulations, outlining which areas require special consideration when wiring bathrooms.

Bathroom Zone 0

Refers to the interior of the bath or shower as it can hold water. The zoning requirement for Zone 0 is for electrical products to be of a low voltage (max 12V) and rated IPX7. Requires electrical products to be low voltage (max. 12 volts) and be IPX7 (the mechanical protection is unimportant).

Bathroom Zone 1

Refers to the area directly above zone 0 to a height of 2.25m above the shower tray or bath. The zoning requirement for Zone 1 is for electrical products to have an IPX4 rating or better. Or SELV (safety extra low voltage) products may be used to ensure that the transformer is located in Zone 3 or beyond. A 30ma RCD (residual current device) should also be used in this zone to protect the circuit if using a 240v supply on a separate circuit.

Bathroom Zone 2

Refers to the area outside Zones 0 and 1, and it stretches 0.6m horizontally and up to 2.25m vertically. Zone 2 also includes the window sill and window recess is located next to the bath. The zoning requirement for Zone 2 is for electrical products to have an IPX4 or better. The transformer for the SELV unit should be located in zone 3 or beyond.

Not Zoned (was Bathroom Zone 3)

Refers to the area beyond zone 2, stretching 2.4m horizontally and up to 2.25m vertically. This area used to be referred to as Zone 3 but this is no longer defined and any light fitting can go in this area. There is no longer a specified IP number for this area, although some products are marked as not for bathroom use. SELV or shaver units are permitted but all other portable electrical equipment is not.

Use of Equipment

Any electrical item approved for use in a zone may be used in another zone with a higher number, but not in a lower number zone.

IP Codes

The IP Code (Ingress Protection Rating, sometimes also interpreted as International Protection Code) consists of the letters IP followed by two letters and an optional digit. It classifies the degree of protection from the entry of solid objects and water in electrical enclosures.

Equipment for bathrooms

Electrical equipment may be identified as having a certain level of mechanical and moisture protection, these are quoted as 'Ingress Protection' (or IP) numbers - such as 'IPXY', where X and Y are numbers, the X showing the level of mechanical protection and Y showing the level of moisture protection - in both cases, the higher the number, the better the protection.

If a piece of equipment does not have an IP number, it must not be used in zones 0, 1 or 2 (or elsewhere having a wet/damp environment).

Typical electrical items which are marked with IP numbers include:
- Extractor fans
- Lighting
- Heaters
- Electrical shower units
- Shower pumps

Shaver power points are not IP rated, however, if they comply with BS EN 60742 Chapter 2, Section 1, they can be located in zone 2 (or beyond) providing they are unlikely to be the subject of direct spray from any shower.

As well as IP numbers, items may be classed as PELV or SELV.
- Protective Extra-Low Voltage (PELV) - As the name suggests, the item uses low voltage but it is connected to the earth.
- Separated Extra-Low Voltage (SELV) - Again a low voltage system but the output is isolated from the input.

Standard electrical wall fittings (such as wall sockets, flexible cord outlets and fused switches, etc) are not IP rated so cannot be installed within zones 0, 1 or 2.

No standard socket outlets are allowed within 3m of the outer limit of zone 1, and any socket fitted should be on an RCD-protected circuit.

Notes
- When the size of the bathroom extends beyond zone 3 portable electrical equipment must be restricted, e.g. cable length is restricted to ensure it cannot be moved into Zone 3
- Where ceiling heights exceed 2.25m the zones effectively extend up to 3m beyond 3m unzoned.
- Basins are technically not covered but are generally considered to be Zone 2.
- If the space under the bath cannot be accessed without using a tool (i.e. a screwdriver) then the space should be considered as unzoned.

Full details of regulations can be found in the latest copy of the IEE Wiring Regulations.
- All electrical work in a bathroom must be carried out by a qualified electrician, if you have questions in relation to bathroom lighting that is specific to your situation we strongly advise you to contact a professional for further advice.
- All electrical circuits within bathrooms must be protected by Residual Current Devices (RCD) not exceeding 30mA. This applies to all electrical equipment whether it is controlled by a switch in the bathroom or remotely switched.