In wiring diagrams, a green color, sometimes shortened as GR, represents the ground wire. The ground wire may have a yellow strip across the green color and be coded as G-Y.
Standard color codes are important for the correct configuration of electrical systems and for safety purposes, as the wire colors clearly separate the function of each wire in the circuit. Wiring diagrams sometimes make use of color codes, instead of the full color names, to identify the wires being used to connect the various components in the circuit. Most of the diagrams that adopt color codes have a key that explains their meanings.
A white color, represented by WH, denotes a neutral wire carrying current at zero voltage. Black, represented by BK on wiring diagrams, is always used to denote wires carrying current at full voltage, typically the power feed for a switch or an outlet; it is never used for ground or neutral wires. Red, represented as RD, is used for the secondary live wires in a circuit. Red wires can be connected to black wires. Blue and yellow, represented by BL and YL respectively, also show power-carrying wires. However, they are not used to wire outlets for common plug-in devices.