6kA MCB – 40A 1 Pole C Curve (WMC140C)
£1.84
£2.99
18th Ed. Compliant
2-Year Warranty
UK Stock
Free Delivery £30+
Secure Payments With
The WMC140C is a 40 A single-pole 6 kA Miniature Circuit Breaker (MCB) designed for sub-mains, plant feeds and high-load circuits where inrush currents from motors or transformers could trip a B-curve device. Its C-curve tripping profile (5–10 × In) provides extra surge tolerance while ensuring rapid disconnection under fault...
The WMC140C is a 40 A single-pole 6 kA Miniature Circuit Breaker (MCB) designed for sub-mains, plant feeds and high-load circuits where inrush currents from motors or transformers could trip a B-curve device. Its C-curve tripping profile (5–10 × In) provides extra surge tolerance while ensuring rapid disconnection under fault conditions.
Tested to BS EN 60898, the WMC140C fits all Whitecliffe consumer units and standard DIN-rail enclosures. It delivers a 6 kA breaking capacity and 20 000-cycle mechanical life for dependable performance in domestic and light-commercial applications.
Installer Tip: Use C-curve breakers for circuits feeding motors, compressors or sub-boards where brief startup surges occur. Verify Zs, voltage drop and protective coordination to stay BS 7671-compliant.
- 40 A rated current with C-curve (5–10 × In) tripping profile
- 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)
- Service life – 20 000 mechanical / 8 000 electrical operations
| Part Code | Rating | Curve | Typical Use |
|---|---|---|---|
| WMC132C | 32 A | C | Cookers and workshop equipment |
| WMC140C | 40 A | C | Sub-mains and plant feeds |
| WMC150C | 50 A | C | Feed and equipment circuits with high inrush |
The WMC140C delivers 6 kA short-circuit and overload protection for feed and equipment circuits with moderate inrush. For resistive loads use a B Curve MCB, or add earth-fault protection with our Type A RCBOs.
Where is a 40 A C Curve MCB used?
Typically on sub-mains and plant feeds serving equipment with higher startup currents such as motors or compressors.
Is the WMC140C compatible with Whitecliffe boards?
Yes – it fits all Whitecliffe consumer units and standard DIN-rail enclosures.
Can I use this breaker for industrial loads?
Yes, within its 6 kA fault rating. For higher fault-level sites, use our 10 kA MCBs.
What is the difference between B and C curves?
B-curve devices trip at 3–5 × In for domestic circuits; C-curve trip at 5–10 × In for motors and transformers.
Do you supply D Curve options?
Yes – Type D (10–20 × In) MCBs for heavy industrial loads are available on request.
- Part Code: WMC140C
- Type: Single Pole MCB
- Rated Current (In): 40 A
- Curve: C (5–10 × 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 (A2)
- Typical Applications: Sub-mains, plant feeds and equipment with high inrush current
Install the WMC140C by a qualified electrician within a suitable consumer unit or distribution board. Ensure the rating and curve match the circuit design and load characteristics.
- Securely mount on 35 mm DIN rail and verify busbar alignment
- Use C-curve for motors, compressors and feed circuits with inrush current
- Check Zs and voltage drop against BS 7671 limits
- Tighten terminals to manufacturer torque spec and record test results
