Single Module 2 Pole RCBO 40A B Curve WRN40B-030
18th Ed. Compliant
2-Year Warranty
UK Stock
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The WRN40B-030 is a 40A Type A RCBO in a compact single-module, 2-pole design. It combines residual current (RCD) and overcurrent (MCB) protection in one device, detecting both AC and pulsating DC leakage faults. With a switched neutral built in, this RCBO fully isolates live and neutral conductors during a...
The WRN40B-030 is a 40A Type A RCBO in a compact single-module, 2-pole design. It combines residual current (RCD) and overcurrent (MCB) protection in one device, detecting both AC and pulsating DC leakage faults. With a switched neutral built in, this RCBO fully isolates live and neutral conductors during a fault, helping installers meet BS 7671 (18th Edition) compliance while keeping healthy circuits energised.
Installer Tip: The 40A B-curve RCBO is often used for high-load subcircuits and small distribution boards where both overload and earth leakage protection must be combined into one device.
- 40A B-Curve RCBO: Suited to high-load domestic and commercial circuits
- Type A protection: Trips on AC and pulsating DC residual currents
- Compact single-module design: Saves board space
- 2-pole with switched neutral: Disconnects both conductors during faults
- Minimises disruption: Isolates only the faulty circuit
- 18th Edition compliant: BS 7671 Amendment 2 ready
What is a 40A RCBO used for?
It’s typically used for higher-demand circuits or small sub-distribution boards requiring both residual and overload protection.
Does it include switched neutral disconnection?
Yes. The WRN40B-030 fully isolates both live and neutral conductors during a fault, increasing safety for maintenance and compliance.
Can I install this in a standard consumer unit?
Yes. The compact 18mm module width makes it suitable for most UK DIN rail boards.
What’s the main advantage of a B-curve RCBO?
B-curve devices are designed for circuits with low inrush currents (e.g. lighting, general domestic loads). For motor-heavy circuits, a C-curve alternative is recommended.
Is this product compliant with UK regs?
Yes. The WRN40B-030 is certified to BS EN 61009-1 and meets 18th Edition Amendment 2 wiring regulations.
When should I choose a C-curve instead of this B-curve?
For heavier loads or circuits with high inrush, consider the WRN32C-030 C Curve RCBO for better inrush handling.
Other WRN Options
| SKU | WRN40B-030 |
| Device Type | Type A RCBO |
| Current Rating | 40A |
| Curve | B Curve |
| Residual Current | 30mA |
| Poles | 2 Pole (Live + Neutral switched) |
| Module Width | 1 (18mm) |
| Dimensions | 18 × 82 × 77mm |
| Mounting | DIN rail |
| Standards | BS EN 61009-1, BS 7671 |
The WRN40B-030 fits any standard UK DIN rail consumer unit. Installation must be carried out by a qualified electrician, with final testing using a calibrated RCBO tester to confirm tripping performance.
- Occupies a single 18mm module slot
- Compatible with conventional busbar layouts
- Switched neutral ensures safe isolation
- Includes test button for routine verification
