Wire Color Code Table
| Country / system | L1 | L2 | L3 | Neutral | Earth |
|---|---|---|---|---|---|
| US 120/208/240 V | black | red | blue | white | bare copper |
| US 277/480 V | brown | orange | yellow | gray | bare copper |
| US high-leg delta 120/240 V | black | orange (high leg) | red | white | green |
| Canada standard | red | black | blue | white or grey | green or uninsulated |
| Canada isolated 3-phase | orange | brown | yellow | white or grey | green |
| CENELEC (EU; UK from Apr 2004) | brown | black | grey | blue | green/yellow-striped |
| UK & Ireland before Apr 2004 | red | yellow | blue | black | green/yellow-striped |
| Australia / NZ AS/NZS 3000 | red or brown | white (prev. yellow) | dark blue or grey | black or blue | green/yellow-striped |
Wire colors are local law: the same brown conductor is a phase (hot) in Europe, while in North America the phase colors are black, red and blue - and an old British wall box may hold red, yellow and blue phase wires that were legal for decades before 2004. The table lines up the major national schemes side by side: three phase colors, the neutral, and the protective earth. Reading it as a system, two colors are nearly sacred worldwide - neutral is white (US/Canada) or blue (IEC countries), and earth is green, bare copper, or green with a yellow stripe - which is why those two are the first thing to identify in any unknown box.
The schemes disagree on purpose-free history, not engineering: the US National Electrical Code prescribes black-red-blue for 120/208/240 V systems by long convention, Europe harmonized on brown-black-grey under CENELEC rules in the 2000s, and the US runs a second, entirely different trio (brown-orange-yellow) for its 277/480 V buildings. The dangerous residue is legacy wiring: a 1970s British house wired red-yellow-blue-black has red carrying live just like modern brown does, but a trained-in-EU electrician seeing red expects a phase only by luck. Renovation work is exactly where the table earns its keep - identify by testing, then re-mark with numbered sleeves rather than trusting paint.
How to use
- Identify before touching: neutral and earth first (white or blue; green, bare or green/yellow), then confirm the hot conductors with a tester - color is a convention for humans, not a guarantee at the conductor.
- Match the country row before working on imported equipment: a machine wired in Germany (brown-black-grey) arrives in a US panel expecting black-red-blue, and jumpers or relabeling must map the phases deliberately.
- Re-mark every legacy joint: when a pre-2004 UK (red-yellow-blue) or old Canadian circuit is extended with modern cable, sleeve the new conductors with the legacy colors at the joint so the next opener inherits one story, not two.
Frequently asked questions
Which wire colors never change between countries?
The earth and neutral families, almost everywhere. Protective earth is green, bare copper, or green with a yellow stripe - the green/yellow-striped conductor is the closest thing electrical practice has to a universal sign, mandated across IEC countries, adopted in North America (solid green) and written into most national codes independently. Neutral is white or grey in the US and Canada, blue in IEC/CENELEC countries, and both families are protected by a shared rule: these colors may not be used for phase conductors, so anyone opening any box can trust the earth and neutral identification before testing. The exceptions worth knowing are historical, not current: old UK wiring used black for neutral (now a phase color in Europe), and the US allows white only for neutral but grey is equally legal - so the reliable habit is identifying by position and test first, color second, in anything older than about twenty-five years.
Why did the UK and Europe change from red-yellow-blue to brown-black-grey?
Harmonization with the casualty statistics the old scheme caused. CENELEC standardised brown-black-grey for phases, blue for neutral and green/yellow for earth across Europe (the UK adopted it in 2004, two years after the harmonised color table was set), because the old national schemes - UK red-yellow-blue, Germany's earlier black-red-grey - meant a European electrician crossing a border met familiar colors carrying unfamiliar roles. The new scheme also fixed a specific trap: red was a phase in the UK and a neutral-adjacent color elsewhere, while the new brown-black-grey trio has no meaning collision anywhere in the harmonised zone. The permanent legacy problem is two-generation housing stock: circuits installed before the changeover (red-yellow-blue with black neutral) still feed modern extensions (brown-black-grey with blue neutral), so the professional rule is identification and sleeving at every junction - the colors on one side of a joint do not certify the other.
What is the orange wire in North American panels?
It depends which side of the border the panel was made, which is the whole wire-color lesson in one conductor. In US practice orange is a warning label in conductor form: the center-tapped delta (120/240 V high-leg) arrangement has one winding center-tapped to neutral, and the third phase sits at roughly 208 volts to ground instead of 120 - so the NEC requires that high leg to be orange at every termination point, because it measures normal against the other phases but dumps nearly double voltage to neutral, and it is the classic destroyer of wrongly-connected 120 V appliances. You meet it in older commercial buildings with big motor loads. In Canadian isolated three-phase systems, by contrast, orange is simply an ordinary phase - the trio runs orange-brown-yellow - so the same color that means roughly-double-voltage in a US panel is just L1 across the border. Modern wye installs avoid the high-leg topology entirely (all phases at 120 to ground), which is why the orange marker reads as a museum piece in new construction - until you open a 1960s machine shop panel, where it is the color of don't. The portable rule is not the color; it is the measurement: test every conductor to neutral before trusting what its insulation seems to say.
Do wire colors matter at low voltage - thermostats, doorbells, network cable?
Different world, different codes, same habit of verification. Thermostat cable in North America uses letters not phases: red for 24 V power (R), white for heat (W), yellow for cooling (Y), green for fan (G), common (C) in blue or black depending on manufacturer - and because HVAC installers mix brands, the letters on the terminal matter more than the insulation. Doorbell and irrigation wiring is color-agnostic (any pair works, polarity rarely matters). Network cable is the strict one: T568A/T568B pin-outs pair colors to pins exactly (see our RJ45 wiring table), because data pairs depend on their twists, not just their connectivity. The through-line on all three: low-voltage wiring mistakes rarely kill, but they cost hours - so the discipline stays the same as mains work: read the terminal designations, test before trusting, and label what you change. Colors identify intent; only testing identifies state.