Section 701 of BS 7671 divides a room containing a bath or shower into three zones: zone 0 inside the bath or shower tray, zone 1 above it to 2.25 m from the floor, and zone 2 extending 0.6 m horizontally beyond zone 1. Each zone has minimum IP ratings (IPX7 in zone 0, IPX4 in zones 1 and 2) and rules on what equipment may be installed. Regardless of zone, Regulation 701.411.3.3 requires every circuit serving the location to have additional protection by a 30 mA RCD, and Regulation 701.415.2 requires supplementary bonding unless three specific conditions are met. In England, work within the zones is a "special location" under Part P of the Building Regulations.
- Zones: 0 inside the bath or tray; 1 above it to 2.25 m (or 1.2 m radius from a shower head with no tray); 2 a further 0.6 m outwards.
- IP ratings: IPX7 in zone 0, IPX4 in zones 1 and 2 (IPX5 if jets are used for cleaning). Zone 0 is SELV only, 12 V a.c. maximum.
- Every circuit in a bathroom needs a 30 mA RCD, not only the ones in the zones.
- Supplementary bonding can be omitted only if all circuits are RCD protected, meet disconnection times, and the extraneous-conductive-parts are main-bonded.
- No socket-outlets in the zones except a shaver supply unit in zone 2; other sockets must be 3 m from zone 1.
What are the bathroom zones and how are they measured?
A location containing a bath or shower is a special location because water and a wet, unclothed person reduce body resistance and make electric shock far more likely to be fatal. Section 701 applies to any room with a fixed bath or shower, including en-suites and a shower cubicle in a bedroom.
| Zone | Extent | Notes |
|---|---|---|
| Zone 0 | The interior of the bath tub or shower basin | For a shower without a basin, the area on the floor within 1.2 m of the fixed water outlet, to a height of 0.1 m |
| Zone 1 | Above zone 0 within the vertical plane around the bath or basin, from the floor to 2.25 m or to a higher fixed shower head. For a shower without a basin, a 1.2 m radius around the fixed water outlet | Includes the space under the bath if accessible without a tool |
| Zone 2 | The area 0.6 m horizontally beyond the boundary of zone 1, to a height of 2.25 m | For a shower without a basin there is no zone 2; zone 1 is enlarged to 1.2 m |
Zones are measured taking account of fixed partitions with a permanent barrier effect: a fixed shower screen bounds zone 1, a folding bath screen does not. The space under a bath with a screwed panel is outside the zones; with a clip-on panel it is zone 1. Everything outside the zones is still within the location, so the RCD, bonding and socket-outlet rules apply there too.
What IP rating and equipment is allowed in each zone?
An IP rating (Ingress Protection, BS EN 60529) is a two-digit code; Section 701 uses the second digit, protection against water, with X meaning the first digit is not specified.
| Zone | Minimum IP rating | Permitted current-using equipment | Switches and accessories |
|---|---|---|---|
| 0 | IPX7 (immersion) | Only fixed SELV equipment at no more than 12 V a.c. or 30 V d.c., designed for the zone, with the source outside zones 0, 1 and 2 | None |
| 1 | IPX4 (IPX5 if water jets used for cleaning) | Fixed, permanently connected: whirlpool units, electric showers, shower pumps, fans, towel rails, water heaters, luminaires. SELV/PELV at 25 V a.c. or 60 V d.c. maximum | Switches of SELV circuits at 12 V a.c.; the cord of a cord-operated switch |
| 2 | IPX4 (IPX5 if water jets used for cleaning) | Fixed equipment suitable for the zone; luminaires, fans, heaters | Shaver supply units to BS EN 61558-2-5; SELV switches; the cord of a cord-operated switch |
| Outside zones | No minimum from Section 701 | Anything suitable; socket-outlets only 3 m or more from zone 1 (Regulation 701.512.3) | Ordinary switches permitted |
A luminaire marked IP44 meets the zone 1 and 2 requirement; one with no IP marking does not, whatever it looks like. The rating applies to the side exposed to the location.
Showers, shaver units and underfloor heating
An electric shower is fixed equipment in zone 1, rated at least IPX4 and permanently connected, on a dedicated circuit sized for the load (an 8.5 kW shower draws about 37 A at 230 V; 10.5 kW about 46 A) with a 30 mA RCD and a double-pole switch for mechanical maintenance, usually a pull-cord with only the cord inside the zones. A new shower circuit needs an Electrical Installation Certificate, not a Minor Works Certificate; see Electrical Installation Certificate (EIC) Explained.
A shaver supply unit to BS EN 61558-2-5 contains an isolating transformer with no earth reference, so a fault on the razor cannot drive a current through the user to earth; it is the only socket permitted in zone 2. A standard 13 A socket-outlet in a bathroom is a defect unless it is 3 m or more horizontally from zone 1.
Electric floor heating in the location must have a metal sheath, enclosure or fine-mesh metallic grid connected to the protective conductor of the supply circuit, with 30 mA RCD protection. Check the manufacturer's data; many cheap mats are not suitable.
Why does every bathroom circuit need a 30 mA RCD?
Regulation 701.411.3.3 requires additional protection by an RCD rated at not more than 30 mA for all low-voltage circuits serving the location, and for circuits passing through zones 1 and 2 to serve equipment elsewhere. This is broader than Regulations 411.3.3 (socket-outlets) and 411.3.4 (lighting) because the risk in a bathroom does not depend on which accessory the person touches: the lighting circuit that also feeds the landing, the shower, the fan and the towel rail are all included. An RCD (residual current device) disconnects within 40 ms at 150 mA when a person becomes the leakage path; see RCD Testing Explained: Types, Test Currents and Trip Times. The rule is not retrospective, but a bathroom with no RCD is the first thing an EICR picks up, and the code depends on whether supplementary bonding is present.
When is supplementary bonding required and when can it be omitted?
Supplementary protective bonding connects the exposed-conductive-parts of fixed equipment in the location (shower casing, Class I luminaire, towel rail) to the extraneous-conductive-parts (metal pipes, a metal bath in contact with pipework) so that during a fault they rise in potential together. It was mandatory in every bathroom until the 17th Edition in 2008. Main protective bonding of incoming services is always required; see What is main protective bonding? Explained.
Regulation 701.415.2 allows supplementary bonding to be omitted where all three of the following are met:
| Condition | What it means on site |
|---|---|
| All final circuits of the location meet the disconnection times of Regulation 411.3.2 | Zs of every circuit serving the room is within the limit for its device, verified by test; see Maximum Zs Values BS 7671: Tables, 80% Rule and Ze |
| All final circuits of the location have 30 mA RCD additional protection | Every circuit, not just those in the zones |
| All extraneous-conductive-parts are effectively connected to the main protective bonding under Regulation 411.3.1.2 | The metal pipes entering the room are continuous back to the main-bonded services, confirmed by test |
If any condition is not met, supplementary bonding is required. The third condition catches people: all-plastic pipework has nothing to bond, but a house where copper has been partly replaced with push-fit may have a towel rail pipe no longer continuous to the bonded incoming water. Test between the pipe and the main earthing terminal with the installation isolated; IET guidance treats 0.05 Ω as effectively bonded, and tens of thousands of ohms means the part is not extraneous at all. Where supplementary bonding is installed, the conductor is 4 mm² copper, or 2.5 mm² if mechanically protected, and may run under the bath.
Is bathroom work notifiable under Part P?
In England since April 2013 the notifiable work under Part P is a new circuit, a consumer unit replacement, and any addition or alteration to an existing circuit in a special location, which for a bathroom means the space around the bath or shower to 2.25 m high and 0.6 m out, corresponding to zones 0 to 2. A new shower circuit is notifiable anywhere; moving a light fitting in zone 1 is notifiable; replacing a switch outside the zones is not. Wales retains a wider list. Use a competent-person scheme (NICEIC, NAPIT and others) or notify building control; see Part P Notification Explained: What Electrical Work Is Notifiable.
What are the common bathroom observations on an EICR?
The following are coded in line with Electrical Safety First Best Practice Guide 4.
| Finding | Usual code | Notes |
|---|---|---|
| No 30 mA RCD protection to circuits serving the bathroom, supplementary bonding present and sound | C3 | The bonding provides protection; recommend RCD |
| No 30 mA RCD protection and no supplementary bonding (or bonding absent where required) | C2 | Neither measure in place |
| 13 A socket-outlet within zones or less than 3 m from zone 1 | C2 | Regulation 701.512.3 |
| Luminaire in zone 1 or 2 with no IP rating or below IPX4 | C2 in zone 1; C2 or C3 in zone 2 depending on exposure | Judge the likelihood of water reaching live parts |
| Class I luminaire or accessory with no cpc connection | C2 | Fault protection absent |
| Supplementary bonding conductor disconnected, or clamp on painted pipe | C2 where bonding is relied on; C3 where the 701.415.2 conditions are otherwise met | Test it |
The coding logic is at EICR Codes Explained: C1, C2, C3 and FI (with examples). A C2 makes the report unsatisfactory and, for a rented property in England, starts the 28-day remedial clock under the Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020. Word the item precisely (zone, item, IP rating found, circuit, regulation, code) as shown at How to Write EICR Observations That Stand Up.
How Certio helps
Certio produces the EICR, EIC, Minor Works certificate and PAT records on the BS 7671 model forms and turns them into branded PDFs. Photograph the consumer unit and the circuit schedule drafts itself; point the phone camera at a Megger MFT-X1 and the reading goes straight into the schedule of test results, or dictate it while your hands stay on the probes. Suggested observation wording with the regulation reference is there for you to check and confirm. The judgement stays yours; the typing goes. Starter is free for 7 days, then £5 a month.