What color is the neutral wire?

NEC 200.6 requires the grounded conductor to be white or gray, or to have three continuous white or gray stripes, in sizes 6 AWG and smaller.

Can any color be used for hot wires?

Any color except white, gray, green, or green with yellow stripes. Black, red, and blue are convention for 208Y/120 systems and brown, orange, yellow for 480Y/277.

Wire Colors for Neutral and Ground: What the NEC Actually Requires

This question comes through the Ask BONBON app constantly, from apprentices and from homeowners trying to make sense of a junction box. Here is what the NEC actually mandates and what is merely trade convention.

Neutral: white or gray, per 200.6

The grounded conductor, which the trade calls the neutral, must be identified by a continuous white or gray outer finish, or by three continuous white or gray stripes along its length, for conductors 6 AWG and smaller. Larger conductors can be black with white or gray marking tape applied at terminations per 200.6(B). One caution from the field: white in an old switch loop is not always neutral. Modern code, 200.7(C), requires a re-identified white used as a hot to be permanently marked another color at every visible point, but plenty of legacy work never got the tape.

Ground: green, green with yellow stripes, or bare, per 250.119

Equipment grounding conductors may be bare, covered, or insulated, and where insulated they must be green or green with one or more yellow stripes. Sizes larger than 6 AWG can be re-identified at terminations with green marking per 250.119(A). Green is reserved: 250.119 and 200.7 prohibit using green for anything but grounding, and white or gray for anything but the grounded conductor except under the narrow re-identification allowances.

Hots: everything else

Ungrounded conductors may be any color not reserved above. The NEC does not mandate specific hot colors for most systems, but the near universal convention is black, red, blue for 208Y/120 volt three phase, and brown, orange, yellow for 480Y/277. Many shops and some local codes formalize this, and 210.5(C) requires that where a premises has more than one nominal voltage system, each ungrounded conductor be identified by system at every termination and splice point, with the method posted or documented.

The orange one that bites

On a 120/240 volt three phase delta with a high leg, 110.15 requires the high leg, which sits about 208 volts to neutral, to be marked orange or another effective means at every connection point. Land a 120 volt load on the orange conductor and the smoke tells you why the rule exists.

Color questions sound basic until a miswired box proves otherwise. Ask BONBON gives cited answers on identification rules for any system voltage in seconds.