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. 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. Primary distribution systems consist of feeders that deliver power from distribution substations to distribution transformers. 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. Whether in a home or an industrial facility, this box keeps your electrical setup organized, functional, and efficient. However, the key to. This chapter covers AC electricity generation, distribution, cable sizing and the AC wiring of inverter/charger systems. The following electrical ratings are typical: As a result of locating power transformers and their close-coupled. Its job is to split an incoming electrical power feed into multiple secondary or subsidiary circuits.