C Curve MCBs for Motor Loads & High-Inrush Circuits
C Curve MCBs are miniature circuit breakers designed for circuits with higher inrush currents, such as motors, compressors, pumps, power tools and certain commercial equipment. They provide combined overcurrent and short-circuit protection while allowing for controlled startup surges without unnecessary tripping.
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C curve devices trip between five and ten times their rated current, giving them greater tolerance for equipment that experiences load spikes during startup. They are available in a wide range of ratings and breaking capacities, making them suitable for workshops, plant rooms, garages, commercial boards and circuits with inductive loads.
- C curve tripping characteristics for moderate to high inrush circuits
- Ideal for motor-driven loads such as pumps and machinery
- Available in 6kA and 10kA versions for different fault levels
- DIN-rail compatible single-module designs
- Stable performance on circuits with fluctuating load profiles
C Curve MCBs are the preferred choice when equipment requires a stable supply during startup, without compromising safety or the ability to clear genuine faults quickly.
WKC 3 Pole 10kA MCB – 20A C Curve (WKC320C)
£21.30
The WKC320C 3 Pole 10kA MCB is a 20A C Curve breaker built to safeguard three-phase circuits against overload and short-circuit faults. With a 10kA breaking capacity and full compliance with BS 7671 (18th Edition), it’s ideal for circuits with moderate inrush currents such as...
WKC 3 Pole 10kA MCB – 16A C Curve (WKC316C)
£21.30
The WKC316C 3 Pole 10kA MCB is a 16A C Curve breaker designed to protect three-phase circuits from short-circuit and overload faults. With a 10kA breaking capacity and compliance to BS 7671 (18th Edition), it’s commonly used for industrial loads, EV chargers, motors, and solar...
WKC 3 Pole 10kA MCB – 10A C Curve (WKC310C)
£21.30
The WKC310C 3 Pole 10kA MCB is a 10A C Curve breaker designed to protect three-phase circuits from short-circuit and overload faults. Rated at 10kA breaking capacity and BS 7671 (18th Edition) compliant, it’s widely used in industrial boards, EV chargers, and solar PV installs....
6kA MCB – 6A 1 Pole C Curve (WMC106C)
£2.00
£3.40
The WMC106C is a 6 A single-pole 6 kA Miniature Circuit Breaker (MCB) providing dependable overcurrent and short-circuit protection for lighting and auxiliary circuits with higher inrush current such as LED drivers, transformers and control gear. Its C-curve tripping characteristic (5–10 × In) offers greater...
6kA MCB – 63A 1 Pole C Curve (WMC163C)
£1.84
£2.99
The WMC163C is a 63 A single-pole 6 kA Miniature Circuit Breaker (MCB) designed for large feed and distribution circuits where inrush currents from motors, welders or transformers demand higher tolerance. Its C-curve tripping profile (5–10 × In) provides robust inrush immunity while ensuring rapid...
What Is a C Curve MCB?
A C curve MCB is a miniature circuit breaker that trips when the current reaches between five and ten times its rated value. This allows it to handle higher initial demands without nuisance tripping, while still providing rapid protection under real fault conditions.
Where C Curve MCBs Are Used
- Workshops and garages with power tools or small machinery
- Heat pumps, HVAC systems and compressors
- Industrial and semi-commercial circuits with inductive loads
- Pumps, fans and motors with noticeable startup current
- Plant rooms and distribution boards feeding mixed mechanical loads
B Curve vs C Curve MCBs
B Curve: Trips at 3–5 × rated current. Suitable for lighting and general domestic circuits.
C Curve: Trips at 5–10 × rated current. Correct choice for circuits with motor loads or measurable inrush currents.
When to Specify a C Curve MCB
A C curve device should be used when the connected equipment causes a brief but legitimate surge on startup. Choosing the correct curve type prevents nuisance tripping and ensures stable operation during normal equipment cycles.
- Motor-driven equipment drawing a higher startup current
- Heat pump or HVAC systems with compressor loads
- Workshops and tools with intermittent bursts
- Three-phase equipment needing predictable overcurrent protection
Compliance & Standards
All C Curve MCBs in this category comply with BS EN 60898 and meet the requirements of the 18th Edition Wiring Regulations for overcurrent and short-circuit protection. They are suitable for new installations, upgrades and replacements.
Installer Benefits
C Curve MCBs provide dependable protection for circuits with mechanical or inductive loads. Their tolerance for higher inrush allows equipment to start correctly, while still delivering fast fault clearing and stable operation over time.