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.
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...
Type A RCBO with Surge Protection – 32A B Curve (Solus Pack)
£21.65
The WER32B/Solus is a 32A B Curve Type A RCBO with integrated Surge Protection, supplied as a ready-to-fit Solus Pack. It provides full 30mA residual current protection with overload and short-circuit defence, while the built-in Type 2 SPD ensures compliance with the 18th Edition Wiring...
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...
Type A RCBO – 32A B Curve, 30mA
£12.50
The WRT132B-030 is a 32A B Curve Type A RCBO that delivers overcurrent and 30mA residual current protection in one slimline device. It features switched live and neutral isolation for safe disconnection, a high immunity design to reduce nuisance trips, and bi-directional wiring that makes...
Type A RCBO – 16A B Curve, 30mA
£12.50
The WRT116B-030 is a 16A B Curve Type A RCBO combining residual current and overcurrent protection in one compact device. It features switched live and neutral disconnection for full isolation, a high immunity design to reduce nuisance tripping, and bi-directional wiring for use in solar...
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.