What’s the core difference between an MCB and an MCCB?
An MCB (miniature circuit breaker) protects final circuits typically up to 63A inside a distribution board; an MCCB (moulded case circuit breaker) protects higher-current circuits — generally 100A and above — on distribution panels, main incomers, and heavy feeders.
The distinction isn’t just size — MCCBs are often adjustable, letting an engineer set the trip current within a range, while MCBs come at a fixed rating.
How do you know which one a circuit needs?
If the breaker is protecting an individual socket or lighting circuit inside a distribution board, it’s an MCB; if it’s protecting a whole floor, a generator connection, a large motor, or feeding a distribution panel, it needs an MCCB.
- MCB — sockets, lighting circuits, small appliance circuits, up to roughly 63A
- MCCB — main incomers, floor feeders, motor protection, distribution panel breakers, 100A upward
What does Legrand’s DPX3 MCCB range cover?
Legrand’s DPX3 range runs from 16A up to 1600A across several frame sizes, with fixed and withdrawable versions and both thermal-magnetic and electronic trip units.
The electronic trip version is specified where adjustable protection curves or remote monitoring/communication is needed — standard thermal-magnetic units cover the majority of straightforward protection applications.
Frequently Asked Questions
Can an MCCB replace an MCB in a standard distribution board?
Technically possible on larger boards, but it’s rarely cost-effective — MCCBs cost more than MCBs and standard distribution boards are designed around MCB-sized breakers.
What’s a withdrawable MCCB and when is it needed?
A withdrawable version can be pulled out for maintenance without fully de-energizing the panel — specified on critical installations that can’t tolerate extended downtime for breaker servicing.
Conclusion
If you’re protecting an individual circuit inside a DB, it’s an MCB; if you’re protecting a panel feeder, main incomer, or large load, it’s an MCCB — get this right before ordering, since the two aren’t interchangeable at the enclosure level.