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. 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 stripes). Outgoing line. Single Phase wiring installation is the most common wiring in our homes and residential buildings. Short Circuit Protection: Ensures that any sudden. A distribution board (also known as a service panel or breaker box) is a centralized collection of circuit breakers, fuses, and/or relays used to control and protect the wiring in a home. Choose the right box based on environment (indoor/outdoor), load capacity, and durability. Check for proper IP/NEMA ratings and material quality. Ensure safe placement: install in. 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.