What colour is a neutral conductor?

White or grey, or three continuous white or grey stripes, under NEC 200.6.

What colour is a bonding or grounding conductor?

Green, green with yellow stripes, or bare, under NEC 250.119.

How does a circuit number map to a phase?

On a standard three-phase panelboard, circuits 1 and 2 are phase A, 3 and 4 are B, 5 and 6 are C, then the pattern repeats.

Which phase carries the high leg in a 4-wire delta system?

The NEC puts the high leg on phase B, the centre bus. It is orange or identified by another effective means. Canada puts it on phase A.

Can colour identify an existing conductor?

No. Colour tells you what should be installed; it does not prove what an existing conductor is.

Wire Colour

Choose the system and conductor role, or enter a panel circuit number. The answer comes first; the rule behind it stays visible.

Electrical system

The NEC reserves white, grey and green but does not assign colours to ordinary ungrounded phases. The phase colours shown here are trade convention; the job spec or local practice wins.

Conductor role

Install this colour

This tells you what to install on new work. What is already in the wall is a meter question—verify with a meter before touching anything.

What the NEC requires—and what the trade supplies

NEC 200.6 controls neutral identification and 250.119 controls equipment grounding. For ordinary ungrounded phases, the NEC prohibits reserved colours but does not mandate black/red/blue or brown/orange/yellow; those are trade convention and job-spec choices.

What the circuit number tells you

A standard three-phase panelboard runs A, B, C from left to right or top to bottom. Circuit rows follow that bus order. In a 4-wire delta panel, NEC 408.3(E) puts the high leg on B, the centre bus.

Install by colour; identify by measurement

This tool answers what to install on new work. Legacy wiring, faded insulation and earlier mistakes make colour unreliable as an identification method.

Want to know why you should trust this result? Read how VoltDrop checks its numbers.

Frequently asked questions

What colour is a neutral conductor?: White or grey, or three continuous white or grey stripes, under NEC 200.6.
What colour is a bonding or grounding conductor?: Green, green with yellow stripes, or bare, under NEC 250.119.
How does a circuit number map to a phase?: On a standard three-phase panelboard, circuits 1 and 2 are phase A, 3 and 4 are B, 5 and 6 are C, then the pattern repeats.
Which phase carries the high leg in a 4-wire delta system?: The NEC puts the high leg on phase B, the centre bus. It is orange or identified by another effective means. Canada puts it on phase A.
Can colour identify an existing conductor?: No. Colour tells you what should be installed; it does not prove what an existing conductor is.