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. Outgoing line. It takes the incoming power and safely distributes it to different circuits throughout your building. This serves as the primary source of electrical energy from the mains supply.
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