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. Electrical power enters a distribution box through the incoming lines using what we call a five-wire system. Each of these wires has a specific, non-negotiable purpose: The Phase Lines : You've got three of these bad boys – A, B, and C phases. By convention, we use yellow for A phase, green for B. Primary distribution systems consist of feeders that deliver power from distribution substations to distribution transformers. Many feeders leave substation in a concrete ducts and are routed to a nearby pole. At this. power delivery infrastructure that takes the electricity from the highly meshed, high-volta incoming transmission-level voltage (35 to 230 kV) and steps it down to several distribution primary dized substation lay- outs, transformer sizes, relaying systems, and automation and S y function of a. Forest City Ratner's 32-story residential complex adjacent to Barclay's Arena in Brooklyn, NY, advanced the modular concept with individual building sections constructed at a factory off-site and erected by crane into place. Resiliency from storms and floods involving the relocation of electrical. This arrangement is shown in Radial System with Primary Selectivity. If two utility sources are available, it provides almost the same economic advantages of the radial system in Radial System but also gives greater reliability since the loss of one utility source does not result in a loss of. Check electrical parameters: First understand the basic electrical parameters of Distribution box so that you can have a general understanding of the capacity and performance of the distribution box.