Electrical Wire Color Code — NEC Standards
Which conductor colors the code actually requires, which are trade convention, and what each color means at 120/240 V, 208 V, 480 V and DC.
In the US: white or gray = neutral, green or bare = ground, orange = delta high leg (all required by code). By convention hots are black, red, blue at 120/208/240 V and brown, orange, yellow at 277/480 V.
| Conductor | 120/208 V and 120/240 V | 277/480 V | Required by code? |
|---|---|---|---|
| Phase A / Line 1 | Black | Brown | Convention |
| Phase B / Line 2 | Red | Orange | Convention |
| Phase C | Blue | Yellow | Convention |
| Neutral (grounded conductor) | White | Gray | Yes — white, gray, or three white or gray stripes (200.6) |
| Equipment ground | Green, green/yellow or bare | Same | Yes — green, green with yellow stripes, or bare (250.119) |
| High leg (208 V to neutral) of a 4-wire delta | Orange | — | Yes — orange, on the B phase (110.15, 230.56) |
| Isolated ground | Green with yellow stripe | Same | Convention |
What the NEC actually requires
- Grounded conductor (neutral): continuous white or gray outer finish, or three continuous white or gray stripes on insulation other than green (200.6). Sizes 4 AWG and larger may instead be marked white or gray at terminations.
- Equipment grounding conductor: bare, green, or green with one or more yellow stripes (250.119). Green may not be used for anything else.
- High leg: on a 4-wire delta system with the midpoint of one winding grounded, the phase with the higher voltage to ground must be orange or otherwise clearly marked, and it lands on the B (center) phase in panelboards (110.15, 408.3(E)).
- Multiple voltage systems: identify ungrounded conductors by phase and system, and post the scheme (210.5(C), 215.12(C)).
- Everything else: ungrounded conductors may be any color except white, gray or green.
Residential cable colors
| Cable | Conductors | Typical use |
|---|---|---|
| 14/2 or 12/2 with ground | Black white + bare | 120 V lighting and receptacle circuits |
| 14/3 or 12/3 with ground | Black red white + bare | Three-way switches, multiwire circuits, split receptacles |
| 10/2 with ground | Black white + bare | 240 V water heater — the white is re-identified as a hot with tape or marker |
| 10/3, 8/3, 6/3 with ground | Black red white + bare/green | 120/240 V dryers, ranges, sub-panels |
| NM-B jacket color | Wire size | Circuit |
|---|---|---|
| White | 14 AWG | 15 A |
| Yellow | 12 AWG | 20 A |
| Orange | 10 AWG | 30 A |
| Black | 8 and 6 AWG | 40–55 A |
| Gray | UF-B (any size) | Underground / wet locations |
DC wire colors
| DC conductor | Identification |
|---|---|
| Positive (ungrounded) | Red, or a red stripe, or marked “+” / POSITIVE / POS |
| Negative (ungrounded) | Black, or a black stripe, or marked “–” / NEGATIVE / NEG |
| Grounded conductor | White or gray |
| Equipment ground | Green or bare |
Solar PV circuits follow the same idea: most modern arrays are functionally grounded, so neither DC conductor is white; red is commonly positive and black negative, identified by marking where the cable is black USE-2 or PV wire.
US vs international wire colors
| Conductor | United States (typical) | IEC / Europe / UK | Canada |
|---|---|---|---|
| Line 1 | Black | Brown | Red |
| Line 2 | Red | Black | Black |
| Line 3 | Blue | Grey | Blue |
| Neutral | White / gray | Blue | White |
| Protective earth / ground | Green / bare | Green-yellow | Green / bare |
Frequently asked questions
Does the NEC require black, red and blue for hot wires?
No. The NEC reserves colors for the grounded conductor (white or gray) and the equipment grounding conductor (green, green with yellow stripes, or bare) and requires orange for the high leg of a delta system. Hot conductors may be any other color. Black-red-blue and brown-orange-yellow are trade conventions, though many specifications and some local codes make them mandatory.
When must phase conductors be identified?
Where a building has more than one nominal voltage system, each ungrounded conductor must be identified by phase and system at every termination, connection and splice point, and the method must be posted at each panelboard or documented (210.5(C) for branch circuits, 215.12(C) for feeders).
Can I use white wire as a hot?
Only in limited cases. In a cable assembly, a white conductor may be used as a hot — for a switch loop or a 240 V load — if it is permanently re-identified at every visible point by paint, tape or marker in a color other than white, gray or green. In a switch loop it must be the supply to the switch, not the return.
Can I mark a black wire with green tape and use it as a ground?
Only for conductors larger than 6 AWG (4 AWG and up), which may be re-identified at terminations. Sizes 6 AWG and smaller must have green or green-with-yellow-stripe insulation, or be bare, for their whole length. The same size rule applies to re-marking a conductor white for use as a neutral.
What color is the neutral on a 277/480 V system?
Gray by convention, with white used for the 120/208 V neutral. Where neutrals of different systems share a raceway or enclosure, 200.6(D) requires them to be distinguishable, which is why the two colors are used.
What do the colors on Romex cable jackets mean?
White jacket is 14 AWG, yellow is 12 AWG, orange is 10 AWG and black is 8 or 6 AWG. Gray is UF-B underground cable. It is a manufacturers’ convention introduced in 2001 to make inspection easier; older cable is white regardless of size.
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