What are bathroom zones?

Glossary · Alarms, lighting and home installs

How bathroom zones work

Water and electricity are a dangerous mix, and Electrical Safety First says wet skin lowers the body’s resistance, so a shock can be more severe in a bathroom.^{[4]Electrical Safety First, Electrical safety advice for the bathroom} BS 7671, the British Standard for electrical installations, treats a bathroom as a special location. It divides the room into zones, so the rules get stricter the nearer equipment is to the water.^{[1]NICEIC, Bathrooms and electrics: what you need to know}

Each zone has its own requirements for how water resistant the equipment must be and the maximum voltage allowed.^{[1]NICEIC, Bathrooms and electrics: what you need to know} The IET says zones are a practical way to set these rules unambiguously, because an item is either in a zone or outside it, which can be settled by measurement.^{[2]IET, Section 701 - Locations containing a bath or shower} Walls, doors, floors and fixed partitions can be taken into account where they limit the extent of a zone.^{[2]IET, Section 701 - Locations containing a bath or shower}

Bathroom wiring is regulated work. NICEIC says any installation or alteration within zones 0, 1 or 2 is notifiable under Part P of the Building Regulations. A registered electrician on a competent person scheme can self-certify it, and you should not do the work yourself.^{[1]NICEIC, Bathrooms and electrics: what you need to know}

The zones

The zone sizes and requirements in the table are NICEIC’s summary of BS 7671.^{[1]NICEIC, Bathrooms and electrics: what you need to know} The IET agrees on the heights and the 600 mm width of zone 2, and says that for showers with no basin, zone 1 extends to 1.2 m from the water outlet.^{[2]IET, Section 701 - Locations containing a bath or shower} NICEIC explains that in a wet room or a shower without a tray there is no zone 2, and zone 1 extends to 1.2 m around the fixed shower head.^{[1]NICEIC, Bathrooms and electrics: what you need to know}

Our IP rating page explains the IPX4 label. The IET confirms that Section 701 requires equipment in zones 1 and 2 to be at least IPX4, and that all circuits in the room need RCD protection of no more than 30 mA.^{[2]IET, Section 701 - Locations containing a bath or shower} Electrical Safety First says all circuits in or passing through a bathroom must be protected by an RCD, and that an electric shower must be on its own circuit.^{[4]Electrical Safety First, Electrical safety advice for the bathroom}

What goes where

Lights and fans are the most common bathroom jobs. The IET says the minimum IP rating for a light in zone 1 is IPX4, and that a 230 V bathroom fan is permitted in zone 1 if it is RCD protected and at least IPX4.^{[3]IET, EICR myths (Wiring Matters)} NICEIC adds that equipment in zone 1 must be on the list in BS 7671, with the maker confirming it is designed for that location.^{[1]NICEIC, Bathrooms and electrics: what you need to know}

Switches need care. NICEIC says traditional light switches are not allowed in zones 0, 1 or 2 because of the risk of touching them with wet hands. A pull cord switch is preferred, and a common solution is a standard switch just outside the bathroom door.^{[1]NICEIC, Bathrooms and electrics: what you need to know} Electrical Safety First agrees that a ceiling-mounted pull cord is a better option than a wall light switch.^{[4]Electrical Safety First, Electrical safety advice for the bathroom}

Ordinary sockets are not allowed in a bathroom apart from shaver supply units, unless they can be fitted well clear of the bath or shower.^{[4]Electrical Safety First, Electrical safety advice for the bathroom} In most bathrooms that rules them out, and an electrician will confirm the distance for your room. Do not use extension leads in the bathroom, because that increases the risk of shock.^{[4]Electrical Safety First, Electrical safety advice for the bathroom} Our extractor fan installation and light switch replacement services cover the common jobs.

Example

Fatima in Chapel Allerton has a bath with a fixed shower head and wants a new ceiling light and a shaver socket. She asks a registered electrician to measure the zones. The light sits directly above the bath, so it is in zone 1 if it falls below the 2.25 m line, and it must be at least IPX4.^{[1]NICEIC, Bathrooms and electrics: what you need to know}

The shaver socket must be a shaver supply unit, which NICEIC says can go in zone 2.^{[1]NICEIC, Bathrooms and electrics: what you need to know} Her electrician fits a pull cord for the light, tests the circuits and notifies the work under Part P.^{[1]NICEIC, Bathrooms and electrics: what you need to know}

What people get wrong

Many people think bathroom electrics are only a concern right over the bath. The zones extend 600 mm beyond zone 1, and any bathroom circuit needs RCD protection, wherever it is. A light a little way from the shower can still be in zone 2 and need to be IPX4.

The second mistake is thinking the work is minor. Any installation or alteration in zones 0, 1 or 2 is notifiable, and mistakes put people at risk of shock.^{[1]NICEIC, Bathrooms and electrics: what you need to know} A registered electrician can tell you which zone an item falls in for your own bathroom.

The bottom line

Bathroom zones are the areas around a bath or shower that decide which electrical equipment is allowed, with stricter rules nearer the water. Zone 0 is inside the bath or tray, zone 1 is above and around it and zone 2 extends 600 mm further. Equipment in zones 1 and 2 must be at least IPX4, all bathroom circuits need RCD protection, and the work is for a registered electrician.