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.
Type A RCBO – 20A B Curve, 30mA
£12.50
The WRT120B-030 is a 20A B Curve Type A RCBO that combines overcurrent and residual current protection in a single compact device. Featuring switched live and neutral disconnection for full isolation, bi-directional wiring for solar and EV applications, and a high immunity design to minimise...
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 – 40A B Curve (WRB140B-030)
£11.67
The WRB140B-030 High Immunity Type A Mini RCBO is a 40A B Curve protective device for residential and commercial circuits requiring higher current handling. At just 18mm wide, it combines overload, short-circuit, and residual current protection in a single compact module. With 30mA Type A...
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 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...
What Is a B Curve RCBO?
A B curve RCBO combines overcurrent, short-circuit and earth leakage protection in one module. It trips quickly under fault conditions and is calibrated for circuits with low inrush loads commonly found in homes and small commercial spaces.
Where B Curve RCBOs Are Used
- Lighting circuits including LED and mixed lighting loads
- Ring mains and general socket circuits
- Small power circuits with predictable inrush behaviour
- Smart home / low-energy systems with steady load profiles
- Retrofit upgrades where replacing grouped RCD circuits with RCBOs improves separation
Benefits of B Curve Protection
B curve devices are designed to trip between three and five times their rated current, providing fast protection without unnecessary tripping on standard household loads. They are particularly suited to circuits without motors or high start-up currents.
- Reliable disconnection for domestic fault levels
- Lower risk of nuisance tripping compared to more sensitive curves
- Ideal match for circuits with stable startup characteristics
Compliance & Standards
All B Curve RCBOs in this category comply with the requirements of BS 7671 (18th Edition) and follow the performance characteristics of IEC/EN 61009. Devices are tested for accurate disconnection times and meet modern consumer unit safety expectations.
Choosing the Correct Rating
Selecting the right rating depends on the load, cable capacity and installation environment. Common ratings include 6A, 10A, 16A and 32A, each suited to specific circuit types. Matching the curve and rating to the actual install conditions ensures stable long-term performance.
Installer Benefits
B Curve RCBOs offer clean circuit separation, simplified testing and safer layouts on modern boards. Their compact form factor helps maintain tidy wiring routes, reduces fault-finding time and supports long-term compliance for both domestic and small commercial premises.