C Curve MCBs
Type C MCBs , also called C curve circuit breakers or Type C breakers , are used on circuits with higher start-up current than standard domestic loads. They provide overload and short-circuit protection while allowing motor-driven and inductive...
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Type C MCBs
Type C MCBs, also called C curve circuit breakers or Type C breakers, are used on circuits with higher start-up current than standard domestic loads. They provide overload and short-circuit protection while allowing motor-driven and inductive equipment to start without unnecessary tripping.
Common uses include compressors, pumps, HVAC equipment, heat pumps, workshop machinery, commercial distribution boards and circuits where a B curve MCB may trip too easily during normal start-up.
Quick answer: A Type C MCB typically trips at 5–10 times its rated current under magnetic fault conditions. This makes C curve MCBs suitable for circuits with moderate inrush current, such as motors, compressors, HVAC and some commercial equipment.
Choose the MCB curve based on the connected load, circuit design, fault level and manufacturer requirements. C curve devices are not a default upgrade from Type B; they should be selected where the inrush characteristics of the load justify the higher magnetic trip threshold.
- C curve tripping characteristic – typically 5–10 × rated current
- Higher inrush support – useful for motors, pumps, compressors and HVAC
- 6kA and 10kA options – choose based on prospective fault current and board requirements
- DIN rail mounting – suitable for compatible consumer units and distribution boards
- BS EN 60898 options – check individual product specification before ordering
For related protection, browse our B Curve MCBs, 10kA MCBs, RCBOs and circuit protection devices.
When to Specify a C Curve MCB
A C curve MCB has a higher instantaneous magnetic trip threshold than a B curve device, which can suit loads with moderate inrush current. It should only be selected when the circuit calculations, fault current and required disconnection times support that characteristic.
Single-Pole C Curve MCBs
Used on suitable final circuits with higher starting current. Select the amp rating from the design and confirm compatibility with the distribution board.
Multi-Pole C Curve MCBs
Two-, three- and four-pole formats support different supply and isolation arrangements. Confirm which live conductors must be switched.
6kA & 10kA Options
The breaking capacity must be at least suitable for the prospective fault current at the installation point; it is separate from the trip curve.
Specification Checklist
- Inrush current: confirm the load genuinely requires a C curve characteristic
- Current rating: coordinate with design current and conductor capacity
- Disconnection time: verify the available fault current will operate the device quickly enough
- Breaking capacity: match the prospective short-circuit current
- Pole and board format: check conductor switching, module width and manufacturer compatibility
Related Categories
B Curve MCBs10kA MCBs3-Pole MCBs4-Pole MCBsRCBOs
Trade support: UK-stocked products, manufacturer-backed specifications and fast dispatch. Check each product page for ratings, standards, stock status and delivery details before ordering.