The main switch, or main breaker, controls the entire electrical supply to the distribution box. It's typically rated for the maximum current capacity of the electrical. A main switch box is essential to your home's electrical system. In this article, we'll take a closer look at mains electric boxes - what they are, what they do, and why they are so important. In an emergency, flipping this switch cuts power to all. Distribution board is a safe system designed for house or building that included protective devices, isolator switches, circuit breaker and fuses to safely connect the cables and wires to the sub circuits and final sub circuits including their associated Live (Phase) Neutral and Earth conductors.