We deals with L&T Miniature Circuit Breakers (MCB) are used to interrupt a circuit during overload and short circuits. It can be used as an alternative to fuses for domestic applications. The advantage of MCBs over fuses is that MCBs are reusable even after interruption of the circuit after an overload or short circuit. Moreover, MCBs are more sensitive to faults than fuses. The capacity range of these MCBs are 0.5A to 125A.