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 model and rated breaking current of the incoming line. 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 model and rated breaking current of the incoming line. 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. Simply put, a power distribution box acts as the central hub for routing energy from an incoming service line — typically supplied by a transformer or substation — to individual branch circuits. By breaking power into smaller, manageable loads, the box ensures consistent delivery while protecting. Distribution boxes help in organizing electrical circuits enabling proper organization in control and management preventing system failure and danger across homes, businesses, and industries. What is the function of a Distribution Box? A distribution box can also be called a distribution board or a. 1) Generally, the incoming line of power distribution box adopts five wire system, that is, a, B and C three-way phase line (the general color is yellow, green and red), one way zero line (the color is light blue) and one way ground line (the color is yellow with green stripes). Make poor choices here, and you're potentially looking at: Electrical systems are like a.