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US, AC:The US National Electrical Code only mandates white (or grey) for the neutral power conductor and bare copper, green, or green with yellow stripe for the protective ground. In principle any other colors except these may be used for the power conductors. The colors adopted as local practice are shown in Table
below. Black, red, and blue are used for 208 VAC three-phase; brown, orange and yellow are used for 480 VAC. Conductors larger than #6 AWG are only available in black and are color taped at the ends.
US AC power circuit wiring color codes.
FunctionlabelColor, commonColor, alternativeProtective groundPGbare, green, or green-yellow greenNeutralNwhitegreyLine, single phaseLblack or red (2nd hot) Line, 3-phaseL1blackbrownLine, 3-phaseL2redorangeLine, 3-phaseL3blueyellow