Guides

The NEC assigns colors to neutrals and grounding conductors. It does not assign colors to phase conductors — black/red/blue and brown/orange/yellow are trade convention, not code. Here is what the code actually requires, and how phase marking with tape is done correctly.

OSHA's color standard covers exactly two colors. Most of what people call "the OSHA colors" comes from ANSI Z535.1, which is voluntary — and ASME A13.1 assigns different meanings to some of the same colors on pipes. Here is what each system actually says, and which parts are legally enforceable.