MCB vs MCCB: Understanding the Difference for Industrial Panels
Current rating range, breaking capacity and typical applications compared.
MCBs and MCCBs both protect circuits from overload and short circuit, but they are built for different current ranges and different jobs. Choosing the wrong one leaves a panel under-protected or hard to maintain.
MCB: miniature circuit breaker
An MCB is used for final circuits and small loads, with ratings typically up to 63 A or 125 A, depending on the maker. The trip settings are fixed, with the overload and short-circuit levels set by the breaker's type. Common curves are B, C and D, which differ in how high a surge current the breaker tolerates before tripping.
MCCB: moulded case circuit breaker
An MCCB is used for higher currents, with ratings that run from about 16 A up to 1,600 A or more. Many MCCBs have adjustable overload and short-circuit trip settings, so they can be set to the load and coordinated with other devices. They have a higher breaking capacity than MCBs.
Key differences
- Current range: MCB for small circuits; MCCB for large feeders and motors.
- Trip adjustment: MCB fixed; MCCB often adjustable.
- Breaking capacity: MCCBs are generally higher.
- Size and cost: MCCBs are bigger and more expensive.
- Add-ons: MCCBs commonly accept accessories such as shunt trips, auxiliary contacts and earth-fault modules.
How to choose
Pick the rating from the load current and the cable's capacity. Check that the breaker's breaking capacity is higher than the prospective short-circuit current at that point in the panel. Choose the curve or trip settings to suit starting currents; motor circuits need a breaker that tolerates the starting surge. Where several breakers are in series, coordinate them so only the one nearest the fault trips.
Consult the standards
Panel design must follow the applicable electrical standards and local regulations. Have the selection checked by a qualified electrical engineer for any design involving safety or large loads.
Key Takeaways
- MCBs for small final circuits; MCCBs for larger feeders and motors.
- Breaking capacity must exceed the available short-circuit current.
- Have the final selection confirmed by a qualified engineer.
This article is general guidance. For a recommendation for your own application, contact our engineering team. Industrial electrical products →