Hello

Can anybody explain me the difference between a MCCB (Molded Case Circuit Breaker) and a MCB (Miniature Circuit Breaker?). Usually, the MCCB is big in size as compare with MCB. Can we use MCB in the place of MCCB in light load applications?
Thanks for any input.

Generally, the main difference (if the amperage is the same) is in the device's ability to withstand a fault. MCBs are only capable of very low available fault currents, Somewhere in the neighborhood of 5kA. So in most cases they must be used behind some kind of current limiting device. MCCBs on the other hand can usually be used in much higher fault current conditions.

Here in the US it gets more complicated because most of the MCBs are not UL listed as "circuit breakers" but as "Supplementary Circuit Protectors", meaning that they CANNOT be used unless they have some other device up stream, such as an MCCB, which makes them only useful when you have a lot of smaller downstream loads.

AB,

The shortcircuit rating is the prominent difference.

MCCB have have many times more fault-current rating, than MCB.

Hence MCB ( Miniature circuit breakers) are used on light loads, and help in fault-clearance at lower level.

chaterpilar

My friends,
many thanks.

Now I have understood that the difference between these two circuit breakers is only the interrupt capacity against short circuit current. At lower level short circuit applications (5ka), we can use either MCCB or MCB-but MCB is cheaper than MCCB, so we use MCB.

I think that is a good assessment.

Just to add some further clarification.

MCB = Miniture Circuit Breaker, used for domestic, light commercial and light industrial applications.

MCCB = Moulded Case Circuit Breaker used in heavy commercial and heavy industrial applications.

And as stated above fault current rating is greater, generally much greater with the MCCB eg:

MCB 4 to 16kA

MCCB 25 to 85kA and possibly greater.

not really... if u search for 100A MCB... it could be expensive as it is not a norm size and not produce in mass... where as 100MCCB could be cheaper...

Hello Hung,

We are not talking about the hiegher raiting MCBs. Mostely, the MCBs are produced upto 63A. For more hiegher raiting, MCCBs are recommneded for use.