Wire color codes

Pick the system, then tap a circuit number to see its phase and wire color.

What the code requires, and what's just convention

Neutral: white or gray, or three white or gray stripes on another color, is required (200.6). Use white on 120/208 V and gray on 277/480 V when both are in one building.
Equipment ground: green, green with yellow stripes, or bare (250.119). Never use green for anything else.
High leg: on a 4-wire delta it must be marked orange (110.15) and land on the B phase in panels (408.3(E)).
Phase colors like black, red, blue and brown, orange, yellow are industry habit, not NEC rules. Where a building has more than one system, the scheme has to be posted at each panel (210.5(C), 215.12(C)). Follow the posted scheme and the job spec.
Neutrals and grounds 4 AWG and larger can be re-identified with tape or paint at each termination (200.6(B), 250.119(A)). Smaller ones need white, gray or green insulation. Hots can be any other color.
Always verify with a meter. Some panels are numbered or phased differently, and old work may not follow any scheme.