what does an mcb do
The MCB-Miniature Circuit Breaker. An MCB is a form of fuse (protective device) which overcomes the traditional problem associated with fuses in so much as when one blows it does not need to be replaced as a fuse does or in older fuses, the wire does not need replacing.CB's operate when they sense an overload, or over current, and become an automatic switch, turning off, or tripping, the MCB when it detects such an overload.