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.
Read more
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.
Type A RCBO – 32A B Curve, 30mA
£14.50
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...
High Immunity RCBO – 16A B Curve, Type A, 30mA (WER16B-030)
£19.80
The WER16B-030 is a 16A B Curve High Immunity Type A RCBO designed for solar PV, battery storage, and EV charger circuits. It provides combined overload, short-circuit, and 30mA residual current protection, with added resilience against nuisance tripping from harmonics or transient voltages. With double...
High Immunity Type A Mini RCBO – 40A B Curve (WRB140B-030)
£11.85
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...
Type A RCBO – 25A B Curve, 30mA
£14.50
The WRT125B-030 is a 25A B Curve Type A RCBO combining residual current and overcurrent protection in one slim device. It features switched live and neutral disconnection for safe isolation, high immunity electronics to reduce nuisance trips, and bi-directional wiring suitable for solar PV, EV...
Type A RCBO – 10A B Curve, 30mA
£14.50
The WRT110B-030 is a 10A 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 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.