6kA MCB – 20A 1 Pole B Curve (WMC120B)
£1.84
£2.99
18th Ed. Compliant
2-Year Warranty
UK Stock
Free Delivery £80+
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The WMC120B is a robust 20 A single-pole 6 kA Miniature Circuit Breaker (MCB) providing accurate overcurrent and short-circuit protection for socket and radial circuits in homes, garages and light-commercial buildings. It features a B-curve tripping profile that operates at 3–5 × rated current to avoid nuisance tripping while ensuring...
The WMC120B is a robust 20 A single-pole 6 kA Miniature Circuit Breaker (MCB) providing accurate overcurrent and short-circuit protection for socket and radial circuits in homes, garages and light-commercial buildings. It features a B-curve tripping profile that operates at 3–5 × rated current to avoid nuisance tripping while ensuring rapid fault disconnection.
Fully tested to BS EN 60898, the WMC120B mounts onto standard 35 mm DIN rails and fits all Whitecliffe consumer units. It’s suited to heavier-duty radials, ring final circuits and small machinery loads where reliable 6 kA protection is required.
Installer Tip: Ideal for 20 A radial socket circuits or feed circuits to outbuildings. Verify voltage drop, Zs and protective coordination before final connection to maintain BS 7671 compliance.
- 20 A rated current with B-curve (3–5 × In) tripping characteristic
- 6 kA breaking capacity at 230/400 V AC
- Single-pole design – 18 mm module width
- DIN-rail mounted for consumer units and distribution boards
- Complies with BS EN 60898 and BS 7671 (18th Edition A2)
- Tested mechanical life – 20 000 operations
- Electrical life – 8 000 operations
| Part Code | Rating | Curve | Typical Use |
|---|---|---|---|
| WMC116B | 16 A | B | Socket and small-power radials |
| WMC120B | 20 A | B | Heavier socket or radial circuits |
| WMC132B | 32 A | B | Cookers, heaters and high-load circuits |
| WMC120C | 20 A | C | Radials with higher inrush currents (e.g. motors, EV chargers) |
The WMC120B offers dependable 6 kA protection for radial and socket circuits. For installations with motors or transformer-based loads, see our C Curve MCB range or upgrade to Type A RCBOs for combined overcurrent and earth-fault protection.
What does the 20 A rating mean?
It’s the maximum continuous current the WMC120B can carry without tripping. The device will operate when the circuit load exceeds 20 A within its thermal tolerance curve.
When should I use a 20 A B Curve MCB?
Use on 20 A radial socket or feed circuits where loads are steady and inrush currents are low. For motors or heavier equipment, use a C-curve MCB.
Is it compatible with Whitecliffe consumer units?
Yes – the WMC120B fits all Whitecliffe boards and standard 18 mm DIN-rail enclosures.
Can I use it in a garage board or outbuilding?
Yes, provided the enclosure is rated for the environment. Use our IP65 plastic enclosure for external installs.
What’s the difference between B and C curves?
B-curve trips at 3–5 × In and is ideal for domestic circuits. C-curve trips at 5–10 × In and suits circuits with motors or high inrush currents such as EV chargers.
- Part Code: WMC120B
- Type: Single Pole MCB
- Rated Current (In): 20 A
- Curve: B (3–5 × In tripping characteristic)
- Rated Voltage (Ue): 230/400 V AC
- Rated Frequency: 50/60 Hz
- Breaking Capacity (Icn): 6 kA
- Insulation Voltage (Ui): 500 V
- Impulse Withstand (Uimp): 4 kV
- Dielectric Test Voltage: 2 kV for 1 minute
- Thermal Reference Temp: 30 °C
- Operating Temperature: –5 °C to +40 °C (avg < 35 °C)
- Mechanical Life: 20 000 operations
- Electrical Life: 8 000 operations
- Mounting: 35 mm DIN rail (1 module width)
- Standards: BS EN 60898; BS 7671:2018 (Amendment 2)
- Typical Applications: Radial socket circuits, feed circuits to outbuildings or small equipment loads
Install the WMC120B in a suitable consumer unit or distribution board by a qualified electrician. Confirm the MCB rating and curve type match the circuit design and protective device coordination.
- Secure DIN-rail mounting with proper busbar alignment
- Use B-curve for standard radials and socket circuits
- Confirm cable size and Zs meet 16–20 A design criteria
- Choose C-curve for motors or EV circuits with higher inrush
- Torque terminals to specification and log test results on EIC forms
