MCB-Miniature Circuit Breaker An MCB, or Miniature Circuit Breaker, is an electrical safety device that automatically interrupts the flow of current in a circuit when it detects an overload or short circuit. It protects electrical circuits from damage by cutting off power in such situations. Unlike fuses, MCBs can be reset and reused after the issue is resolved. What is MCB. MCB Stands for Miniature Circuit Breaker. It automatically switches OFF electrical circuit during any abnormal condition in the electrical network such as overload & short circuit conditions. However, fuse may sense these conditions but it has to be replaced though MCB can be reset. MCB stands for Miniature Circuit Breaker, MCCB for Moulded Case Circuit Breaker, and RCCB for Residual Current Circuit Breaker (also known as RCD or Earth Leakage Circuit Breaker). All three are types of circuit breakers used for different purposes in electrical systems to protect against overcurrent and faults. An MCB (Miniature Circuit Breaker) uses a thermal-magnetic tripping mechanism to protect electrical circuits from overload and short circuits. This involves a bimetallic strip for overload protection and an electromagnet for short circuit protection.