B Curve RCBOs for Domestic & Light Commercial Circuits
B Curve RCBOs are designed for standard domestic and light commercial circuits where inrush currents are low and predictable. They provide combined overcurrent and earth leakage protection in a single device, making them the preferred choice for modern boards where every circuit requires its own dedicated protection.
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These RCBOs trip within the B-curve range, meaning they respond quickly to fault currents that reach three to five times the rated current. This makes them ideal for lighting circuits, ring finals, small power circuits and general domestic loads. Most models include a switched neutral and are suitable for both new installs and retrofit upgrades.
- Combined MCB and RCD protection in one device
- B-curve response for low-inrush domestic circuits
- Accurate disconnection times for 18th Edition compliance
- Switched neutral options for improved testing and safety
- Suitable for tight consumer unit layouts due to compact module size
Installers choose B curve RCBOs for clean circuit separation, reduced nuisance tripping and simpler periodic inspection. All product dimensions and ratings are provided within the individual listings.
Important: A B curve RCBO refers to the magnetic trip characteristic (3–5× rated current). This is different from a Type B RCBO, which relates to DC earth leakage detection for EV or inverter systems.
High Immunity RCBO – 20A B Curve, Type A, 30mA
£18.67
The WER20B-030 is a 20A B Curve High Immunity Type A RCBO designed for residential and light commercial circuits including solar PV, battery storage, and EV-ready boards. It combines overload, short-circuit, and 30mA residual current protection in one device, while its high immunity design helps...
High Immunity Type A Mini RCBO – 20A B Curve (WRB120B-030)
£11.67
The WRB120B-030 High Immunity Type A Mini RCBO is a 20A B Curve protective device designed for residential and commercial circuits. Its compact 18mm width combines overload, short-circuit, and residual current protection in one unit. With 30mA Type A sensitivity and high immunity against nuisance...
High Immunity Type A Mini RCBO – 6A B Curve (WRB106B-030)
£11.67
The WRB106B-030 High Immunity Type A Mini RCBO is a compact 6A B Curve device that combines residual current and overcurrent protection in a single 18mm module. Designed for boards where space is limited, it provides 30mA Type A protection, detecting AC and pulsating DC...
High Immunity Type A Mini RCBO – 16A B Curve (WRB116B-030)
£11.67
The WRB116B-030 High Immunity Type A Mini RCBO is a 16A B Curve device designed to protect small power and lighting circuits while saving space in the board. At just 18mm wide, it combines residual current and overcurrent protection in one compact module. With 30mA...
High Immunity RCBO – 40A B Curve, Type A, 30mA
£18.67
The WER40B-030 is a 40A B Curve High Immunity Type A RCBO designed for heavier duty residential and commercial circuits, including solar PV, battery storage, and EV-ready consumer units. It combines overload, short-circuit, and 30mA residual current protection with enhanced resistance to nuisance tripping caused...
What Is a B Curve RCBO?
A B curve RCBO is a residual current breaker with overload protection that trips magnetically between three and five times its rated current. This fast trip response makes it suitable for circuits with low and predictable inrush currents.
B Curve vs C Curve RCBO
Understanding RCBO curve types is essential when selecting protection:
- B Curve: Trips at 3–5 × rated current. Ideal for lighting and general domestic socket circuits.
- C Curve: Trips at 5–10 × rated current. Used for circuits with motors, pumps or higher startup loads.
If the connected equipment has minimal startup surge, a B curve device is normally specified.
Common Applications
- Lighting circuits (including LED)
- Ring final socket circuits
- General domestic power
- Consumer unit upgrades replacing split RCD boards
- Small commercial circuits with stable loads
Available Ratings & Configurations
Most B curve RCBOs are available in:
- 6A – lighting circuits
- 10A / 16A – radial circuits
- 20A / 32A – socket circuits and small appliances
- Single-module DIN rail format
- Switched neutral variants
Standards & Compliance
All devices comply with BS EN 61009 and meet the requirements of BS 7671 (18th Edition). They are fully compatible with modern metal consumer units and support independent circuit protection.