Wire Color Codes
Wire color conventions for US (NEC), IEC (European), and low-voltage thermostat wiring.
| Function | Region | Color | Voltage |
|---|---|---|---|
| US (NEC)-Hot 1 / Line | US (NEC) | Black | 120/240V |
| US (NEC)-Hot 2 / Line | US (NEC) | Red | 120/240V |
| US (NEC)-Hot 3 / Line | US (NEC) | Blue | 120/240V |
| US (NEC)-Neutral | US (NEC) | White | 120/240V |
| US (NEC)-Ground | US (NEC) | Green / Bare | 120/240V |
| US (NEC)-Traveler | US (NEC) | Red / Black | 120V |
| US (NEC)-Switch leg | US (NEC) | Black | 120V |
| IEC-Line 1 | IEC | Brown | 230V |
| IEC-Line 2 | IEC | Black | 230V |
| IEC-Line 3 | IEC | Grey | 230V |
| IEC-Neutral | IEC | Blue | 230V |
| IEC-Ground | IEC | Green/Yellow | 230V |
| Thermostat-Heat (Rh/Rc) | Thermostat | Red | 24V |
| Thermostat-Cooling (Y) | Thermostat | Yellow | 24V |
| Thermostat-Fan (G) | Thermostat | Green | 24V |
| Thermostat-Heat (W) | Thermostat | White | 24V |
About this lookup
- What color is ground?
- US: green or bare. EU: green/yellow stripe. Always check local code.
- What if a wire is the wrong color?
- Do not assume. Always test with a multimeter before touching.