Arc Fault Detection A-Type RCBO – WFD120B-030 (20A, B Curve, 30mA)

The WFD120B-030 is a 20A, B Curve Arc Fault Detection (AFDD) RCBO, combining arc fault detection, 30mA Type A residual current protection, short-circuit, and overload protection in a single compact unit. Fully compliant with BS 7671:2018 (18th Edition), it provides advanced fire prevention for modern electrical systems.

Unlike conventional RCBOs, this AFDD RCBO includes a microprocessor-based detection system that identifies arc faults caused by damaged conductors, loose connections, or faulty appliances. Once detected, the device trips instantly and isolates both live and neutral poles, ensuring maximum safety.

Protective Coverage

The WFD120B-030 combines the functionality of:

• Arc Fault Detection – protects against series and parallel faults
• Residual Current Protection – Type A, 30mA (AC and pulsed DC leakage)
• Overcurrent Protection – short-circuit and overload
• Overvoltage Protection – trips at 275V ±5%

Variant Comparison

• SKU: WFD120B-030
• Type: AFDD + Type A RCBO
• Rating: 20A
• Curve: B
• Residual Current Sensitivity: 30mA
• Breaking Capacity: 6kA
• Operating Voltage: 230V AC, 50Hz
• Arc Fault Detection: Series & Parallel
• Additional Protection: Overcurrent, earth leakage, overvoltage (275V ±5%)
• Isolation: Disconnects live and neutral (switched neutral)
• Mounting: 1 module DIN rail
• Dimensions: 17.8 × 116 × 76 mm
• Standards: BS EN 61009-1, BS EN 62606, BS 7671:2018 (18th Edition)

Installation must be completed by a qualified electrician in line with BS 7671. AFDD RCBOs are recommended for high-risk circuits such as sleeping accommodation and commercial premises.

• 20A version suited for socket circuits and kitchen appliances
• Single-phase 230V AC circuits only
• DIN rail mounted, 1 module (17.8mm wide)
• Not for use on DC circuits
• Compatible with WCED consumer units

What circuits is the WFD120B-030 best for?

It is ideal for socket outlet circuits, kitchen appliances, and small commercial installs where fire protection is crucial.

Does this AFDD RCBO isolate both conductors?

Yes – it disconnects both live and neutral poles, offering complete isolation.

Is this device compliant with UK wiring regulations?

Yes – it is certified to BS EN 61009-1, BS EN 62606, and meets BS 7671:2018+A2.

What is the difference between this AFDD RCBO and a standard 20A RCBO?

The AFDD RCBO detects dangerous arc faults, a leading cause of electrical fires, which standard RCBOs cannot detect.

What other current ratings are available?

The WFD1 Series includes 6A, 10A, 16A, 32A, and 40A. This page covers the 20A WFD120B-030.