The mandatory colors for power wiring in the National Electrical Code (NEC) are Green, Bare, or Green/Yellow (a yellow stripe or band on green) for the protective ground (PG), and White (or alternatively Gray) for the neutral wire. Most European countries follow a wire color code established by the International Electro-technical Commission (IEC). This article is for reference only. The various colored wires that you can see when you look behind a switch or an outlet are not an accident, but rather a safety feature that is built in. Wiring color codes are. Electrical engineers, contractors, traders, manufacturers, and especially electricians worldwide rely on different wiring color codes for wire and cable installations in industrial buildings and residential homes. The colors help us determine each wire's function and purpose.