Black: Signifies a hot or live wire, responsible for transporting electricity. Red: Often used in switch configurations or as a. In household wiring, a black wire is a live (hot) conductor that carries current from the source to loads; never use it as neutral or ground. Color tells a story in every junction box. If you're. The black wire is one of the most frequently encountered colors in residential and commercial installations, and its function is tied directly to the delivery of power. Green or Bare: Ground wires, directing excess. Black is probably the first colour about which you should know in the electrical wire colour code. Black wires designate 'hot' wires.