Part P & BS 7671 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).

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.

In England, AD P 2013 (still current) notifiable electrical work is limited to three categories: (a) installation of a new circuit; (b) replacement of a consumer unit; (c) any addition or alteration to existing circuits in a "special location" — which AD P defines as rooms containing a bath or shower, and swimming pool/sauna rooms. Since 2013, kitchens and outdoor areas are NO LONGER special locations (unless they overlap with a bath/shower room). Work in kitchens or gardens that does not involve a new circuit or CU replacement is not in itself notifiable. 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).

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.