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. A distribution board or distribution box is where the main power supply is distributed to multiple loads. What is Distribution Board? Distribution board. Connection method: Each switch takes a wire from the incoming point and connects it to the incoming end of the switch, or uses parallel connection to reduce the difficulty of wiring.