Bathroom Zone IP Ratings: A Complete Wiring Safety Guide (BS 7671)

Bathrooms are the most regulated rooms in a home when it comes to electrical safety. Water and electricity are a lethal combination, which is why the UK's BS 7671 (IET Wiring Regulations) divides bathrooms into zones — each with its own minimum IP rating and voltage restrictions.

Zone 0 is the interior of the bathtub, shower basin, or sink. This zone is continuously wet. Only 12V SELV (separated extra-low voltage) equipment rated IP67 or higher is permitted. That means downlights inside a shower enclosure must be IP67 and fed from a 12V transformer located outside Zone 0.

Zone 1 is the area directly above the bath or shower, up to 2.25 meters from the floor. Water jets and spray are expected here. The minimum rating is IP65 (dust-tight + water jets). Mains voltage (240V) is allowed but must be protected by a 30mA RCD (residual current device). Extractor fans mounted above a shower typically need IP65.

Zone 2 extends 0.6 meters horizontally from the edge of the bath or shower. Splashing water is possible but not direct jets. IP44 (splash-proof) is the minimum. Beyond Zone 2, no specific IP rating is required by BS 7671, but IP20+ is good practice for any bathroom fitting.

A common mistake is installing a standard IP20 downlight above a shower. This violates Zone 1 requirements (IP65 minimum) and creates a serious safety hazard. Water ingress into a mains-voltage fitting can cause short circuits, electric shock, or fire. Always check the IP rating printed on the fitting's packaging before installation.

All electrical work in bathrooms must be carried out by a qualified electrician and notified to the local building control authority. Bathroom circuits must be protected by a 30mA RCD. Switches should be located outside the bathroom or use pull-cord switches rated for the appropriate zone. For more details, refer to BS 7671 Section 701.