Bathroom Electrical Zones: What Can Go Where?

Quick Answer: BS 7671 Section 701 divides bathrooms into Zone 0 (inside the bath/shower tray), Zone 1 (above the bath/shower to 2.25 m height), Zone 2 (0.6 m beyond Zone 1), and Outside Zones. Each zone has strict IP rating and equipment requirements. Only SELV at 12V AC or 30V DC is permitted in Zone 0; all bathroom circuits require 30 mA RCD protection.

Summary

Bathroom electrical zones exist because water and mains electricity are a lethal combination. BS 7671:2018+A2:2022 (the IET Wiring Regulations, 18th Edition) Section 701 defines the zones for any room containing a bath or shower, and specifies what equipment can be installed in each, what IP rating it needs, and how circuits must be protected. The zones are based on proximity to the water source -- the closer to the bath or shower, the stricter the requirements. Every electrician and plumber working in bathrooms needs to understand these zones because non-compliant installations are both dangerous and illegal under Part P of the Building Regulations. Getting it wrong can mean failed inspections, insurance issues, and serious risk to life.

Key Facts

Zone Definitions

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Zone 0

What it is: The interior of the bath tub or shower tray itself -- any volume that can hold water during normal use.

Dimensions: The space contained within the bath or shower basin, up to the rim or threshold.

IP rating required: Minimum IPX7 (protection against temporary immersion in water up to 1 m depth for 30 minutes).

What is allowed:

What is NOT allowed:

Zone 1

What it is: The volume directly above Zone 0 (above the bath or shower tray), extending upward to 2.25 m from finished floor level. For showers without a tray, Zone 1 extends 1.2 m from the centre point of the fixed shower head, measured horizontally.

Dimensions:

IP rating required: Minimum IPX4 (protection against splashing water from all directions). Where water jets are used for cleaning purposes, minimum IPX5 (protection against low-pressure water jets).

What is allowed:

What is NOT allowed:

Zone 2

What it is: The area extending 0.6 m horizontally beyond the boundary of Zone 1, and above the bath/shower up to 2.25 m from finished floor level. Also includes the area above Zone 1 up to the ceiling if the ceiling height exceeds 2.25 m (though some interpretations treat this as outside zones -- check with your scheme provider).

Dimensions:

IP rating required: Minimum IPX4 (protection against splashing water from all directions). Where water jets are used for cleaning, minimum IPX5.

What is allowed:

What is NOT allowed:

Outside Zones

What it is: Any area in the bathroom beyond Zone 2 -- more than 0.6 m from the Zone 1 boundary and/or above 2.25 m from finished floor level.

What is permitted:

Practical note: In most UK bathrooms (typically 2-3 m wide), there is very little or no space that qualifies as "outside zones." This effectively means no 13A sockets in the vast majority of bathrooms.

Equipment Guide

Equipment Zone 0 Zone 1 Zone 2 Outside Zones
Light fitting SELV 12V only, IPX7 Yes, IPX4 min Yes, IPX4 min Yes, standard
Downlight (recessed) No Yes, IPX4 min (check enclosure behind ceiling too) Yes, IPX4 min Yes, standard
Electric shower No Yes, permanently connected, RCD protected N/A (wouldn't be here) N/A
Extractor fan No Yes, IPX4 min, permanently connected Yes, IPX4 min Yes, standard
Electric towel rail No Yes, IPX4 min, permanently connected (not plugged in) Yes, IPX4 min, permanently connected Yes (can be plugged in if 3 m+ from Zone 1)
Shaver socket (BS EN 61558-2-5) No No Yes Yes
13A socket outlet No No No Yes, if 3 m+ from Zone 1 boundary
Standard light switch No No No Yes
Pull-cord switch No Switch body must be outside zone (cord can hang in zone) Switch body must be outside zone Yes
Heated mirror / demister pad No Yes, if IPX4 min and permanently connected Yes, if IPX4 min Yes
Whirlpool / jacuzzi unit Yes, SELV 12V, IPX7 Yes, permanently connected, IPX4 N/A N/A
Instantaneous water heater No Yes, permanently connected, IPX4 min Yes, IPX4 min Yes
Underfloor heating May be installed beneath Zone 1/2 if it has an earthed metallic sheath or grid, or is covered by an earthed metallic grid connected to the protective conductor Same Same Yes
Electric mirror light SELV 12V only, IPX7 Yes, IPX4 min Yes, IPX4 min Yes, standard

Key for the table:

Detailed Guidance

Where can I install a light in a bathroom?

Lights can be installed in Zones 1 and 2 provided they carry a minimum IP rating of IPX4. In Zone 0, only SELV 12V fittings rated to IPX7 are permitted -- this is rare and mainly applies to underwater feature lighting in baths.

For recessed downlights in a ceiling above Zone 1, pay attention to the back of the fitting as well. If the void above the ceiling is within Zone 1 (i.e. the ceiling is below 2.25 m), the rear of the fitting also needs appropriate protection. Many IP65-rated downlights are designed for this purpose -- IPX4 on the face, fully sealed at the rear.

Pull-cord light switches are the standard solution in bathrooms. The switch mechanism itself must be located outside the zones, but the pull cord can hang down into zoned areas.

Can I install a shaver socket in a bathroom?

Yes, but only in Zone 2 or outside zones, and it must be a dedicated shaver supply unit complying with BS EN 61558-2-5. These units contain an isolating transformer that limits the risk of electric shock. They are not the same as a standard 13A socket -- a standard socket is never permitted in Zones 0, 1, or 2.

Shaver sockets are typically mounted near the mirror/basin area. Since the basin area is usually Zone 2 (0.6 m from the basin edge), placement next to or above the mirror is normally compliant.

Where can I install an extractor fan?

Extractor fans are commonly installed in Zone 1 (directly above the shower) or Zone 2. The fan must be rated to at least IPX4 in either zone. If water jets are used for cleaning in the area, IPX5 is required.

The fan must be permanently connected (hardwired), not plugged in. The isolating switch for the fan should be located outside the bathroom or be a pull-cord type with the switch body outside the zones. If the fan is on the lighting circuit (which is common), it still needs its own means of isolation.

In practice, many bathroom extractor fans are rated IP44 or IP45, which covers Zones 1 and 2 respectively.

Do I still need supplementary bonding?

Under BS 7671 Regulation 701.415.2, supplementary bonding can be omitted in a bathroom provided all three of the following conditions are met:

  1. All final circuits of the location comply with the requirements for automatic disconnection of supply (Regulation 411.3.2)
  2. All final circuits of the location have additional protection by means of a 30 mA RCD
  3. All extraneous-conductive-parts of the location are effectively connected to the main protective equipotential bonding (Regulation 411.3.1.2)

In practice, in a modern installation with a consumer unit fitted with RCBOs or RCDs protecting all bathroom circuits, and where main bonding is confirmed to gas, water, and other services, supplementary bonding is not required.

However, if you cannot confirm all three conditions -- for example, in an older property where the consumer unit lacks RCD protection on the bathroom circuit, or where main bonding is absent or suspect -- supplementary bonding must be installed. This means connecting all extraneous-conductive-parts (exposed metallic pipework, radiators, baths, etc.) together with 4 mm2 earth cable.

Practical advice: Always test and verify. If you are adding a new bathroom circuit, fit RCD protection and confirm main bonding, which removes the need for supplementary bonding. If you are working on an existing installation and cannot verify the conditions, install supplementary bonding -- it is cheap insurance.

Frequently Asked Questions

Can I have a socket outlet in a bathroom?

A 13A socket outlet is only permitted if it is outside all zones and at least 3 m horizontally from the Zone 1 boundary. In the vast majority of UK bathrooms, this is physically impossible due to room size. The exception is shaver supply units (to BS EN 61558-2-5), which are permitted in Zone 2 and outside zones. If you need to charge electric toothbrushes or shavers, a shaver socket with a built-in USB outlet is the compliant solution.

Does a cloakroom / WC without a bath or shower need zoning?

No. Section 701 only applies to rooms containing a bath or shower. A WC with just a toilet and basin does not require zoning, and standard socket outlets and switches can be installed. However, if the room later has a shower added, the zoning requirements will then apply retrospectively to all existing equipment.

What about wet rooms?

Wet rooms follow the same zone definitions, but because there is no shower tray, the zone measurements are taken from the fixed shower head. Zone 1 extends 1.2 m horizontally from the centre of the shower head. The floor of the entire wet room is effectively Zone 0 or Zone 1 depending on design, which has implications for underfloor heating installations.

Do these rules apply to en-suites and hotel bathrooms?

Yes. Section 701 applies to all locations containing a bath or shower in domestic, commercial, and hospitality settings. En-suites, hotel bathrooms, gym showers, and care home wet rooms all follow the same zoning rules.

Who can do electrical work in a bathroom?

Under Part P of the Building Regulations (England and Wales), electrical work in a room containing a bath or shower is notifiable work if it involves a new circuit or alteration to an existing circuit within the zones. This means it must be either:

A like-for-like replacement of a fitting (e.g. swapping one IPX4 light for another) is generally not notifiable, but adding a new circuit for a shower or moving a fan to a different zone is.

Regulations & Standards