3 Phase RCDs (4-Pole) for Three-Phase Earth Leakage Protection
3 phase RCDs provide residual current protection across all three live phases and the neutral conductor. These 4-pole three-phase RCD units are used on distribution boards, sub-mains and plant circuits where full earth leakage protection and simultaneous disconnection are required.
Quick answer: A 3 phase RCD is usually a 4-pole earth leakage device that monitors L1, L2, L3 and neutral together. If a fault is detected, it disconnects all poles simultaneously to provide safe isolation on a three-phase circuit or distribution board.
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These 4-pole RCDs disconnect L1, L2, L3 and N simultaneously during a fault, preventing dangerous imbalance or partial isolation. Available in 30mA, 100mA and 300mA sensitivities, they support both personal protection and fire-rated selective protection depending on the application.
- 4-pole (3P+N) protection for standard three-phase circuits
- 30mA, 100mA and 300mA options for shock or fire protection duties
- Type A and Type B variants depending on load characteristics
- Suitable for three-phase boards, sub-mains and plant circuits
- Used as three-phase RCD units or RCD breakers depending on the assembly
- 18th Edition aligned for new installations and upgrades
These devices are essential wherever three-phase equipment is installed and offer guaranteed, simultaneous disconnection for safe maintenance and reliable protection against earth leakage faults.
A Type Time Delay RCD – 100A 100mA, 4 Pole (WARTD4100-100)
£54.10
The WARTD4100-100 A-Type 100mA Time Delay RCD is a 4 Pole S-Type device rated at 100A for large-scale three-phase boards. Designed for upstream use, its time delay ensures proper discrimination, allowing downstream RCDs to trip first and keeping supply integrity across unaffected circuits. It’s a...
4 Pole Type A RCD – 80A High Immunity (WAR480-030)
£37.50
The WAR480-030 is a 4 pole, 80A Type A RCD with high immunity, designed for demanding three-phase applications where nuisance tripping must be avoided. Fully compliant with BS EN 61008-1 and BS EN 61008-2-1, it provides dependable residual current protection for distribution boards, EV chargers,...
4 Pole Type A RCD – 100A High Immunity (WAR4100-030)
£37.50
The WAR4100-030 is a 4 pole, 100A Type A RCD with high immunity, designed for heavy-duty three-phase applications where maximum load capacity and nuisance-trip resistance are critical. Compliant with BS EN 61008-1 and BS EN 61008-2-1, it delivers reliable residual current protection for three-phase distribution...
4 Pole B-Type RCD – WEV463B-030 (63A, 30mA)
£158.30
The WEV463B-030 is a 4 Pole Type B RCD (63A, 30mA) designed for higher-load applications where smooth DC and high-frequency leakage currents may be present. Unlike Type A RCDs, it detects AC, pulsed DC, and smooth DC residual currents up to 1000 Hz, ensuring full...
What Is a 3 Phase RCD?
A 3 phase RCD is typically a 4-pole residual current device that monitors earth leakage across L1, L2, L3 and neutral. In many assemblies it acts as the main three-phase RCD unit or upstream RCD breaker protecting plant, boards or outgoing ways.
Where 3 Phase RCDs Are Used
- Three-phase distribution boards in commercial and industrial buildings
- Motors, pumps and compressors requiring leakage detection
- HVAC and ventilation systems
- Sub-mains feeding secondary boards
- Machinery circuits where neutral isolation is required
30mA vs 100mA vs 300mA
30mA: Personal protection on circuits feeding equipment directly accessible to users.
100mA: Fire protection or upstream protection where selectivity is needed.
300mA: Commercial/industrial fire protection or main incomer RCDs with selective delay.
Type A vs Type B Three-Phase RCDs
Type A: Detects AC + pulsed DC leakage. Suitable for many three-phase loads.
Type B: Detects smooth DC leakage. Required for VFDs, inverters, large motors and EV/renewables-related equipment.
RCD Unit or RCD Breaker?
In three-phase switchgear, buyers often search for a 3 phase RCD unit or 3 phase RCD breaker. In practice, both phrases usually refer to the same protective function: a three-phase residual current device used within a board or assembly to provide earth leakage protection and full multi-pole disconnection.
Why Most 3 Phase RCDs Are 4-Pole
Most three-phase installations use 4-pole RCDs because they monitor and disconnect all three phases plus neutral together. That gives full isolation and avoids leaving part of the circuit live during a fault or maintenance situation.
- Simultaneous phase and neutral isolation
- Suitable for balanced and unbalanced three-phase loads
- Common format for three-phase distribution boards and sub-mains
- Safer maintenance access without partial isolation
Some specialist installations may use a 3-pole RCD where no neutral is present, but most commercial and general three-phase board applications use a 4-pole format.
Compliance & Standards
All 3 Phase RCDs in this category meet BS EN 61008 / BS EN 61009 requirements and support 18th Edition Wiring Regulations for three-phase leakage protection.
Installer Benefits
3 Phase RCDs offer predictable disconnection, improved safety and full isolation for plant equipment, motors and distribution circuits. Their 4-pole format ensures safe working conditions and stable protection across multi-phase loads.