The difference between molded case circuit breaker and miniature circuit breaker

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The difference between molded case circuit breaker and miniature circuit breaker
12 04 , 2021

Moulded case circuit breaker(MCCB ) provides protection for overload and short circuit in low voltage power distribution system and motor protection loop. Because of its reliability and stability, it has been widely used in industry. Miniature circuit breaker (MCB ) is also used in a wide range and a large number of circuit breaker products, the main function is to provide protection for building electrical terminal power distribution device. Because both belong to the circuit breaker, and MCCB is mostly used for small capacity on and off, so understand the difference between the two, choose the right product is very realistic and important. Here’s a quick explanation.
Let’s start with the basic similarities, because they are both circuit breakers, they both have to follow some basic product standards, and they work the same way. Let’s talk about the differences between them. Generally speaking, there are the following points:

  1. Different electrical parameters
  2. Different mechanical parameters
  3. Different working environments

In addition set out from the Angle of choose and buy, say a few both distinction specifically.

Current rating

Molded case circuit breakers have current grade up to 2000A. The maximum current grade of the miniature circuit breaker is within 125A. Due to the gap between the two in capacity, in the specific work, the effective area of the molded case circuit breaker is greater than the miniature circuit breaker, and the access wire is relatively thick, can reach more than 35 square meters, and the miniature circuit breaker is only suitable for the following 10 square meters of wire. Therefore, the general indoor situation, the larger room is more suitable for the choice of molded case circuit breaker.


Molded case circuit breaker is mainly screw mounted, easy to press, good contact, stable operation. And the micro circuit breaker is mainly installed through the guide rail, sometimes due to insufficient torque and cause poor contact. Because of their different installation methods, molded circuit breakers are more stable and less difficult to install than miniature circuit breakers.

Operation and life

Operationally. Molded case circuit breaker adopts two sets of devices to protect overcurrent and short circuit respectively, and the action value of overcurrent protection can be manually adjusted, convenient and rapid. Miniature circuit breakers share a set of devices for overcurrent and short circuit, and the current cannot be adjusted, resulting in many cases unable to solve the problem. Plastic case circuit breaker phase distance, and arc cover, arc extinguishing ability is strong, can withstand greater short-circuit current, and not easy to cause phase short circuit, so that the service life is also more than the miniature circuit breaker.

Flexibility of use

In this respect, molded case circuit breakers are more prominent, and their flexibility in setting is better than miniature circuit breakers. The overcurrent and short circuit protection devices of MCCB are independent, and the action value of overcurrent protection can be adjusted flexibly. The over current protection and short circuit protection of the MCB are unified devices, and there are certain deficiencies in the flexibility of regulation. According to the above situation seems to be the MCB in the wind, but in fact for some time, or need to choose the MCB.
For example, the need to improve the safety of the line, because the MCB action sensitiy is high, breaking action is fast, more conducive to the protection of the line and electrical appliances. It can be seen that both have their own advantages and suitable for use, the key is to fully understand the difference between molded case circuit breaker and miniature circuit breaker, and according to their own needs to choose.

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