Each wire powers one “bus” (copper vertical leg) inside the main service panel. That’s why you usually see two columns of circuit breakers (or fuses) when you open your service panel door.

Every branch circuit in your home, as well as the main service conductors, are protected by circuit breakers (or fuses, if you have an older home, although that’s not as common anymore).

An MCB (miniature circuit breaker) can be reset and uses an electromagnet to open a switch if the current goes above a certain value. MCBs switch off the current faster than a fuse. An RCCB ...

Even if you aren’t an electronics person, you probably have a working knowledge of circuit breakers. When the lights go out, you find the circuit breaker and flip it back to the on position.