Primary Distribution Box: Serves as the main distribution box for a construction site or project (usually only one). Each fuse is designed to blow when the current exceeds a certain limit, thereby cutting off the power to prevent damage. With one input and several outputs, these boxes allow multiple devices to connect through the distro. Equipment inside usually includes isolating switches, circuit breakers, and residual current devices (RCDs). Supplies power to specific buildings or floors. Equipped with larger three-phase circuit. Electrical systems power our homes, offices, and industrial facilities, but behind every reliable electrical setup lies a crucial component that often goes unnoticed: the distribution box. The outgoing line from the low-voltage end of the transformer is 0.