RCDs – Residual Current Devices for Domestic & Commercial Installations
RCDs (Residual Current Devices) are designed to disconnect a circuit when they detect current leaking to earth. They are used to help reduce the risk of electric shock and electrical faults, and remain a core part of modern board design across domestic, commercial, and three-phase installations.
This collection includes a range of RCD types, sensitivities, and formats, helping electricians choose the right device for standard final circuits, selective protection arrangements, and more specialist applications.
Quick answer: An RCD is a protective device that trips when it detects earth leakage current. The right type of RCD depends on the installation, the connected equipment, and whether the circuit needs standard, time-delayed, or more specialist residual current protection.
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Different RCD types in the UK are suited to different electrical loads and installation designs. This range supports both standard and more specialist applications, with options for common domestic board layouts as well as higher-demand or three-phase systems.
- Type A RCDs – suitable for AC and pulsating DC residual current on many modern circuits
- Type AC RCDs – for AC residual current only, depending on the application
- 30mA devices – commonly used where additional personal protection is required
- 100mA and time-delay options – used where selective or upstream protection is part of the design
- Specialist RCD formats – including options for three-phase and more demanding applications
Need combined overload and residual current protection? Browse our RCBO range. For DC-sensitive applications, see our Type B RCDs. For delivery and returns, visit our delivery information and returns policy.
Heat Pump RCD -B Type 2 Pole - WHP240-030
£136.30
The WHP240-030 is a compact Type B RCD specifically designed for heat pump systems – including Vaillant and other inverter-driven installs where full DC fault protection is required. Unlike Type A or Type AC RCDs, this 2 pole device is engineered to detect smooth DC...
Heat Pump Consumer Unit 8 Way (WME08/HP40C)
£174.50
Pre-wired in the UK and tested before dispatch – allow up to 3 working days for shipping. The WME08/HP40C Heat Pump Consumer Unit is a dedicated protection board for inverter-driven heat pump systems. It comes pre-fitted with a 40A Type B RCD, a 40A Type...
4 Pole Type A RCD – 40A High Immunity
£22.20
The WAR440-030 is a 4 pole, 40A Type A RCD with high immunity, engineered to reduce nuisance tripping on circuits affected by surge currents or harmonics. Fully compliant with BS EN 61008-1 and BS EN 61008-2-1, it provides reliable residual current protection for three-phase distribution...
Heat Pump Consumer Unit 10 Way (WME10/HP40R25)
£234.55
Pre-wired in the UK and tested before dispatch – allow up to 3 working days for shipping. The WME10/HP40R25 Heat Pump Consumer Unit is a dedicated protection board for inverter-driven heat pump systems. It comes pre-fitted with a 40A Type B RCD, a 25A MCB,...
4 Pole Type A RCD – 63A High Immunity
£22.20
The WAR463-030 is a 4 pole, 63A Type A RCD with high immunity, engineered to reduce nuisance tripping on circuits affected by surge currents or harmonics. Fully compliant with BS EN 61008-1 and BS EN 61008-2-1, it provides reliable residual current protection for three-phase distribution...
What Is an RCD?
An RCD, or Residual Current Device, is a protective device that monitors the balance of current flowing through a circuit and disconnects the supply if it detects leakage to earth. In practical terms, that means it helps protect against electric shock and certain earth fault conditions.
Types of RCDs in the UK
One of the most common search questions is about RCD types in the UK. The right type depends on the connected equipment and the design of the installation.
- Type A RCDs – used on many modern circuits and suitable for AC plus pulsating DC residual current. See our Type A RCDs.
- Type AC RCDs – designed for AC residual current only.
- Type B RCDs – used where smooth DC residual current may be present, such as some EV, inverter, and specialist applications. Browse Type B RCDs.
- Specialist types – including devices for variable frequency or more sensitive electronic loads where the design requires them.
30mA, 100mA & Time-Delayed RCDs
RCDs are also selected by sensitivity and operating characteristic, not just by type.
- 30mA RCDs – commonly used where additional personal protection is part of the circuit design
- 100mA RCDs – often used in upstream or more selective protection arrangements
- Time-delayed RCDs – used where discrimination and coordination with downstream devices is needed
3 Phase RCDs
Three-phase RCDs are used on installations where residual current protection is needed across a three-phase supply. These are commonly found in commercial and industrial settings, and on specialist circuits where a standard single-phase device would not be appropriate.
RCDs vs RCBOs
An RCD provides residual current protection only. An RCBO combines that function with overcurrent and short circuit protection in a single device. If the circuit needs both earth leakage protection and MCB-style protection at circuit level, an RCBO may be the better fit.
Where RCDs Are Used
- Domestic consumer units – for grouped residual current protection
- Commercial boards – where larger or more selective protection arrangements are required
- Three-phase installations – where residual current protection is needed across multi-phase systems
- Specialist circuits – including EV, heat pump, and inverter-related setups where device type matters
FAQs on RCDs
What does RCD stand for?
RCD stands for Residual Current Device.
What are the main types of RCD?
The main types commonly referenced in the UK are Type A, Type AC, and Type B, with the correct choice depending on the nature of the connected load.
What’s the difference between an RCD and an RCBO?
An RCD provides residual current protection only. An RCBO combines residual current protection with overload and short-circuit protection.
How does a 3 phase RCD work?
A 3 phase RCD monitors the current balance across the conductors in a three-phase circuit and disconnects the supply if it detects residual current leakage to earth.
Why Buy RCDs from Power & Data UK?
Power & Data UK supplies trade-focused circuit protection products with dependable UK stock, practical product choice, and fast dispatch. Orders over £30 qualify for free UK mainland next-day delivery, and products are backed by a 2-year manufacturer warranty. For unwanted items, see our returns policy.