What Color Is the Load Wire?
In a circuit, the main load wire — the live power wire between the switch and power source — is typically black, and the secondary load wire is usually red. Wire colors can vary between circuits, so it is best to remove or turn off power sources before touching them.
A yellow and blue striped wire may also be used for power in a circuit, but only in applications that don't require the heavy-duty demands of a traditional wall power outlet. Other colors that may appear in a circuit include green wires for grounding and gray wires for neutral portions of the circuit.