Generally, the incoming line is the air switch, circuit breaker, knife switch or other circuit breaker of three-phase incoming and one-way 3pin; The zero line is pressed to the neutral terminal block, and the ground line is pressed to the grounding terminal block. 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. A distribution box is a low-voltage electrical enclosure that receives incoming power and distributes it safely to multiple outgoing circuits through protective and switching devices such as MCBs, RCDs, RCBOs, fuses, isolators, busbars, neutral bars, earth bars, and surge protective devices. Whether in a home or an industrial facility, this box keeps your electrical setup organized, functional, and efficient. The exposed laying can take the sheath line, or through the pipe and trunking. ① 220V load generally takes one phase line. Hey, in this article we are going to see the Single Phase Distribution Box Wiring Diagram and Connection Procedure.