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Bathrooms and special locationsWhat's allowed in bathroom zone 1?
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A room containing a bath or shower is a special location. That includes a bedroom with a shower enclosure in it. An en-suite is its own room, but it's still a special location. We define zones because the closer you are to water, the higher the shock risk.
- Zone 0: inside the bath or shower tray.
- Zone 1: above the bath or tray up to 2.25 m from the floor (or to the shower head if higher).
- Zone 2: 0.6 m out from the edge of zone 1.
- Under the bath: zone 1 if you can reach it without a tool (no panel, or a panel that comes off by hand). If it takes a tool, such as unscrewing the panel or cutting sealed silicone, it is outside the zones. It is never zone 0.
- Walk-in / wet room with no tray: zone 1 only, extending 1.2 m from the fixed water outlet. There's no zone 2.
- All circuits in the location need 30 mA RCD protection (RCD or RCBO).
- Sockets (other than shaver units) are allowed only at least 2.5 m horizontally from the boundary of zone 1.
- Shaver supply units (BS EN 61558-2-5) are allowed in zone 2 and outside the zones, where direct spray from the shower is unlikely.
- Plate switches go outside the zones, at least 0.6 m from the edge of the bath or shower, and must suit the location. Cord-operated switches are the exception: the cord is allowed into zones 1 and 2.
- Equipment you'll see: a pull-cord switch (on the ceiling above 2.25 m, so the cord can hang into a zone), ceiling lights, a shaver socket, extractor fans, and an electric shower.
- Where does the shower go? On the wall in zone 1, never in zone 0. Fixed equipment in zone 1 needs at least IPX4, or IPX5 if it will be cleaned with water jets. Allowed fixed equipment in zone 1 includes whirlpool units, electric showers and shower pumps, ventilation, towel rails, luminaires and water heaters.
- Shaver socket: it has a safety isolating transformer inside, with a laminated core to reduce eddy-current losses. Because the output is isolated from earth, touching one conductor won't give an earth-path shock.
A shaver socket does not step down to 12 V. A standard shaver supply unit (BS EN 61558-2-5) actually gives an isolated 115 V / 230 V output. It's safe because it's isolated, not because it's low voltage. The 240 V marked on some of them is just the old nominal voltage.
Electrician's Guide to the Building Regs · 5.3 · locations containing a bath or shower: sockets, shaver units, plate switches, luminaires, showers and fans by zone · p.86 Electrician's Guide to the Building Regs · walk-in shower / wet room figure · p.89 Electrician's Guide to the Building Regs · table: minimum IP rating and equipment allowed per zone · p.87
On-Site Guide · Section 8 · zone requirements table (IPX4, IPX5 where water jets used for cleaning) · p.118 BS 7671 · Section 701 locations containing a bath or shower, zones in Regs 701.32.2–4 · from p.257 BS 7671 · Reg 701.32.3: the space under the bath is zone 1, or outside the zones if only accessible with a tool
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