What color are positive and negative wires?

The color of wires is dependent on the method of wiring and where one is located. In the United States, a common two-wire ungrounded circuit has a red positive wire and a black negative wire.

For a two-wire system with a negative ground, the positive wire is red, and the negative wire is white. For a two-wire system with a positive ground, the positive wire is white, and the negative wire is black. Lastly, there are three-wire systems that feature a "center tap" wire, which is colored white. The positive wire for these systems is red, and the negative wire is black.