17 differences between MCB breaker and Fuse

We use an MCB circuit breaker and fuse in the electrical circuits to protect them in electrical circuits. But there are many differences between the MCB breaker and a fuse. I will explain 17 differences between the MCB breaker and the fuse.

The MCB (miniature circuit breaker) is an electromechanical device that protects the electrical circuit from short circuits and over electrical current.

The fuse is a metal wire which melts and opens the electrical circuit due to heating from too much electrical current flowing in the circuit.

Differences between MCB and fuse

There are the following differences between an MCB circuit breaker and a fuse:

1. The MCB trip is as per the thermal and magnetic concepts, and disconnects the electrical circuit just by opening a contact in the circuit. But the fuse works on the principle of the thermal characteristic of the fuse wire material. The material of the wire melts due to overheating, and so the electrical circuit becomes open.
   
2. The size of the MCB breaker is big. But the size of the fuse is small.
   
3. The cost of the fuse is much less than as compared to the cost of the MCB breaker.
   
4. We use a fuse in electronic cards in place of an MCB due to its small size. It is difficult to use MCB in small-sized electronics as the size of the MCB is quite large.
   
5. After tripping, we can reset the MCB and reuse it again and again. But we have to replace the fuse, as we can not reuse the fuse. So the running cost is less for the MCB.
   
6. In case of fault, quick restoration is possible in the MCB, just by switching the ON operation. But we can not restore the fuse without replacing it.
   
7. MCB is more sensitive to overcurrent than a fuse.
   
8. MCB can automatically switch off the circuit during overload, also.
   
9. The handling of the MCB is safer than the use of a fuse in electrical circuits.
   
10. The fuse is available in a single-phase version only. The MCB is available in 3 3-phase version also.
    
11. The fuse operation is faster than the MCB.
    
12. The MCB breaker has manual operation also. But the fuse has no manual kind of operation.
    
13. We can use the MCB for switching ON and OFF operations also. But we can not use a fuse for switching operations in a circuit.
    
14. The fuse is available for low-current use. The MCCB type breaker is available in the high-current version also.
    
15. For very high-voltage circuits, we use the breaker along with an isolator. We do not use fuse for very high voltage applications.
    
16. In the absence of the electric supply, it is easy to disconnect the circuit in case of a fuse, just by removing the fuse. This act like extra safety. Then we can work and do some observations or modifications. However, the MCB breaker can not be removed too easily and fast.
    
17. Special-type breakers can have many built-in protections like leakage current, arc detection ( by AFDD breaker), etc. But the fuse just protects from short-circuit electrical current.

Circuit breakers are available in different types, like MCB, MCCB, AFDD, high voltage breakers, etc. The fuses are also available in different types.

Advantages of MCB over a fuse

As discussed above, the MCB has the following advantages over a fuse:

• It is easy to restore the supply in the case of the MCB
• It is electrically safer to use an MCB
• MCB breaker is reusable after a trip

Disadvantages of MCB circuit breaker over a fuse

MCB has some of the following disadvantages over the fuse:

• MCB is more expensive
• It is big in size
• More difficult to replace than a fuse, if required

Extra knowledge as per experience

In the small circuit, we may use a fuse. But we did not use a fuse in our many electronic circuit cards. This is because the use of electronics was limited to a certain system, and the connection was fixed. And there was no chance of wrong use. Further, our many circuit outputs were electronically protected from short circuits.

But in panels, we used the MCB and MCCB circuit breakers both extensively as per requirements.

In many panels, we use both breakers and fuses. But we did not use fuses for every part of the circuit. The individual block of the circuit was protected by an MCB only.

For further knowledge, watch the MCB working concept video below:

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• What is the voltage of the neutral wire?
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Further, read the difference between MCB and RCCB breakers.

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About the author – G K Agrawal B.Sc and B.Tech (from HBTU Kanpur), Retd. Sr DGM Design (BHEL), the inventor of patents, has lifelong industry experience in the electrical and electronics design field of R&D. He worked for BHEL. He shares his experience and knowledge on blogs and YouTube. Read the profile here.