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. The three-phase five-wire system includes three phase wires (A, B, C wires), neutral wire (N wire), and ground wire (PE wire) of three-phase electricity. The neutral wire (N wire) is the neutral wire. It takes the incoming power and safely distributes it to different circuits throughout your building. It receives power from the main electrical supply and divides it into separate circuits, each. Electrical distribution boxes are used in commercial and residential buildings and are part of the electrical system, also known as switchboards. It integrates power distribution, protection, and monitoring capabilities, and is responsible for distributing power to entire commercial or residential. Arrangement order: The circuit breakers should be arranged from left to right, and the reserved position is generally placed on the right side of the distribution box.