Which circuits require RCD protection?

Under BS 7671:2018+A2:2022 (Regulation 411.3.3 and 411.3.4), 30 mA RCD protection is required for: all socket outlet circuits rated up to 32 A, all circuits in bathrooms (Zone 0-2 and beyond), circuits supplying mobile equipment outdoors, circuits in locations with increased shock risk, and cables concealed in walls at a depth less than 50 mm (unless in an earthed metallic enclosure or protected by 30 mA RCD).

What types of RCD are there?

Type AC detects sinusoidal AC fault currents only. Type A detects AC and pulsating DC faults (required for most domestic circuits under BS 7671). Type F detects AC, pulsating DC, and composite faults from frequency-controlled equipment (e.g. inverter drives, EV chargers). Type B detects all fault types including smooth DC. BS 7671 generally requires Type A as a minimum for domestic installations.

What electrical work is notifiable under Part P?

In England, notifiable electrical work includes: new circuits, consumer unit replacement, work in bathrooms and kitchens (except like-for-like replacements of accessories), work in special locations (swimming pools, saunas), and work outdoors. Non-notifiable work includes replacing accessories (sockets, switches, light fittings), adding fused spurs to existing circuits, and like-for-like replacements. Notifiable work must be either inspected by Building Control or carried out by a competent person registered with a scheme (e.g. NICEIC, NAPIT, ELECSA).

Can an RCD protect against all electric shock?

No. A 30 mA RCD provides additional protection against electric shock but is not a substitute for basic protection (insulation of live parts) and fault protection (earthing and overcurrent devices). An RCD detects earth leakage current — it will not operate if a person touches live and neutral simultaneously without any current flowing to earth. RCDs are a supplementary measure per BS 7671 Chapter 41.

Part P & BS 7671 RCD Protection

Circuits Requiring 30 mA RCD Protection (BS 7671:2018+A2:2022)

Circuit / Location	RCD Required?	Regulation
All socket outlets ≤ 32 A	Yes — 30 mA	411.3.3
Bathroom circuits (all zones)	Yes — 30 mA	701.411.3.3
Circuits supplying mobile equipment outdoors	Yes — 30 mA	411.3.3
Cables concealed in walls (< 50 mm deep)	Yes — 30 mA (unless in earthed metallic enclosure)	522.6.202
EV charge point circuits	Yes — 30 mA Type A min. (Type F for some chargers)	722.531.2
Swimming pool / sauna circuits	Yes — 30 mA	702/703
Lighting circuits	Recommended (required if cables concealed in walls)	522.6.202

RCD Types and Applications

RCD Type	Detects	Typical Application
Type AC	Sinusoidal AC faults only	Not recommended for domestic (legacy)
Type A	AC + pulsating DC faults	Standard for most domestic circuits
Type F	AC + pulsating DC + mixed frequency	Circuits with inverter drives, some EV chargers
Type B	All fault types inc. smooth DC	Industrial, PV systems, some EV chargers

Part P Notification Requirements (England)

Work Type	Notifiable?	Route
New circuit installation	Yes	Building Control or competent person scheme
Consumer unit replacement	Yes	Building Control or competent person scheme
Work in bathrooms / kitchens (new circuits)	Yes	Building Control or competent person scheme
Outdoor electrical work (new circuits)	Yes	Building Control or competent person scheme
Replacing socket outlets, switches, light fittings	No	N/A
Adding a fused spur to existing circuit	No (unless in bathroom/kitchen)	N/A
Like-for-like replacement of accessories	No	N/A

Scotland & Northern Ireland

Scotland does not have a direct equivalent of Part P — electrical work in dwellings is covered under Technical Handbook Section 4.5 (Electrical safety) and compliance with BS 7671 is required. Northern Ireland requires compliance with BS 7671 through Technical Booklet P (Electrical safety) and notifiable electrical work follows a similar but separate scheme. BS 7671 applies across all UK jurisdictions.

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Use the Cable Sizing Calculator for circuit design, or the BS 7671 Circuit Guide for domestic circuit specifications.

Always check the latest edition of Approved Documents on the Planning Portal (planningportal.co.uk) as regulations are updated periodically.

Part P & BS 7671 RCD Protection

Circuits Requiring 30 mA RCD Protection (BS 7671:2018+A2:2022)

RCD Types and Applications

Part P Notification Requirements (England)

Scotland & Northern Ireland

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