RCDs – Residual Current Devices
Residual Current Devices (RCDs) protect against earth leakage faults and electric shock, making them a core part of every 18th Edition installation. Choose from Type A or Type AC RCDs in 30mA or 100mA sensitivities, or step up to Type B RCDs for DC-sensitive installs like EV and solar.
Read more
All RCDs in this range meet BS EN 61008 and 61009 standards and are suitable for both residential and commercial use. They disconnect supply immediately if leakage is detected, protecting against electric shock and reducing fire risk.
- Type A RCDs – detect AC and pulsed DC leakage, now the UK standard for most new installs
- Type AC RCDs – detect AC leakage only, being phased out in many applications
- 30mA sensitivity – personal protection for final circuits
- 100mA sensitivity – time-delayed or selective protection in larger installs
Need combined overload and leakage protection? View our RCBO range. For shipping details, see our delivery information or returns policy.
4 Pole B-Type RCDs
£158.30
The WCED 4 Pole Type B RCD is designed to provide advanced protection for circuits where smooth DC and high-frequency fault currents are present. Fully compliant with IEC/EN 62423, it safeguards against AC, pulsating DC, and smooth DC residual currents up to 1000 Hz –...
2 Pole A-Type 100mA Time Delay RCD
£25.35
The WCED WARTD Series A-Type 100mA Time Delay RCD is designed for upstream fault protection in dual-RCD or discrimination setups. Often called an S-Type RCD, its built-in delay ensures downstream devices trip first, preventing unnecessary power loss across unaffected circuits. Suitable for both single-phase and...
4 Pole A-Type 100mA Time Delay RCD
£30.25
The WCED A-Type 100mA Time Delay RCD is designed for installations requiring RCD selectivity between upstream and downstream devices – often referred to as RCD discrimination. With 100mA sensitivity and a built-in time delay, these devices help ensure only the correct breaker trips in the...
What Is an RCD?
An RCD (Residual Current Device) is a protective switch that cuts power if it detects current leaking to earth. This protects against electric shock and reduces the risk of fire caused by faulty wiring or appliances. Under the 18th Edition Wiring Regulations, RCDs are mandatory on most final circuits in the UK.
Types of RCDs
- Type A – detects both AC and pulsed DC leakage. Recommended for modern appliances, EV chargers, and heat pumps. Example: 2-Pole A-Type 100mA Time Delay RCD.
- Type AC – detects AC leakage only. Still in use but no longer recommended for new domestic installs.
- Type B – DC-sensitive devices for EVs, solar, and heat pumps. See our Type B RCD category.
- Type F – specialist for variable frequency drives and sensitive electronics.
Sensitivity & Ratings
RCDs are available in different ratings to suit their application:
- 30mA – provides personal protection against electric shock, required on most socket and lighting circuits.
- 100mA – typically used for fire protection or selective time-delayed devices in larger installs.
- 300mA+ – used in industrial or commercial systems for equipment/fire protection.
FAQs on RCDs
What’s the difference between an RCD and an RCBO?
An RCD only protects against earth leakage. An RCBO combines RCD and MCB protection in one device.
Are Type AC RCDs still allowed in the UK?
Yes, but Type A RCDs are now strongly preferred under the 18th Edition due to the growing use of electronics and inverter-driven equipment.
How often should RCDs be tested?
They should be tested every 3 months using the “test” button, and formally checked at each EICR or inspection.
Why Buy From Power & Data UK?
All RCDs we supply are BS EN certified, backed by manufacturer warranties, and shipped directly from our UK warehouse. Orders over £30 qualify for free next-day delivery, with optional Saturday upgrades available. Need to send something back? See our returns policy.
Explore Related Categories
- RCBOs – combined protection devices
- High Immunity RCBOs – prevent nuisance trips
- Type B RCDs – DC-sensitive protection
- Circuit Protection – MCBs, RCDs & breakers
- Surge Protection Devices (SPDs)