Red wires are often known as “secondary hot” wires. That means they carry current like a black wire, but they usually work with another switch or outlet. A distribution box is the heart of any electrical system. However, the key to. Connection method: Each switch takes a wire from the incoming point and connects it to the incoming end of the switch, or uses parallel connection to reduce the difficulty of wiring. Wiring Direction: Wiring between the main circuit breaker and each branch circuit breaker in the box generally. Connecting a distribution box involves several steps to ensure proper electrical flow. Fix the box securely to the wall, ensuring it's at an accessible. In this video, we'll walk you through the process of wiring a home distribution box with a detailed connection diagram. These are usually connected to thick black or red wires, each carrying 120V in a split-phase system. Verify voltage with a multimeter: each line wire should show ~120V to neutral and ~240V. 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).