The wiring diagram of main distribution board is composed of an upper panel, a lower panel, the wire connections, and the various circuit breakers. A feeder usually begins with a feeder breaker at the distribution substation. Many feeders leave substation in a concrete ducts and are routed to a nearby pole. To do this, you'll need an understanding of the wiring diagram of main. Wiring Direction: Wiring between the main circuit breaker and each branch circuit breaker in the box generally goes on the left, and the wiring out of the distribution box generally goes on the right. However, the key to. In this video, we'll walk you through the process of wiring a home distribution box with a detailed connection diagram.