The main parts are the Miniature Circuit Breaker (MCB), Residual Current Device (RCD), busbars, and the main switch. Safe habits and checking the box often help stop electrical accidents. Each part. The Distribution box system diagram mainly includes the following parts: Incoming line part: Displays the incoming line source of the distribution box, which may be a single-line incoming line or multiple-line incoming lines (such as normal power supply and backup power supply), and marks the. Learn about the internal structure of a distribution box, its components, functions, and key types. It ensures that circuits are safe, organized, and easy to manage. A properly installed electrical distribution box is important for. A distribution box (distribution board / DB box) receives incoming power from the mains supply and safely distributes it to multiple branch circuits. It improves safety by enabling protection against overload and short circuits, and it improves reliability by keeping circuits separated and clearly.