Electrical Wire Color Codes
The NEC does not mandate specific colors for all conductors, but standard practice and certain NEC requirements (like white for neutral and green for ground) are widely followed. IEC color codes used in Europe and on imported equipment differ from US convention.
Color codes vary by application, country, and age of the installation. Never assume a conductor is safe based on color alone. Always test before touching. We are not liable for any decisions you make based on this information. If you are unsure, consult a licensed electrician. Full disclaimer
US (NEC) and IEC Wire Colors
| Color | US / NEC Use | IEC Equivalent | Notes |
|---|---|---|---|
| Black | Hot (line 1) | Brown (L1) | Most common hot conductor color in US wiring |
| Red | Hot (line 2) | Black (L2) | Second hot in 240V or 3-phase systems |
| Blue | Hot (3-phase line 3, or switched) | Grey (L3) | Third hot in 3-phase; sometimes switched leg in 3-way circuits |
| White | Neutral (grounded conductor) | Blue | Must be identified if used as hot in 240V circuits (tape or sleeve) |
| Gray | Neutral (alternative) | Blue | Acceptable alternative to white for neutral conductors |
| Green | Equipment ground | Green/Yellow | Equipment grounding conductor (EGC) |
| Green/Yellow Stripe | Equipment ground (IEC style) | Green/Yellow | International style; sometimes seen on imported equipment |
| Bare copper | Equipment ground | N/A | Uninsulated EGC in cable assemblies |
| Orange | High-leg delta (wild leg) | N/A | The high-leg (208V) of a 4-wire delta system must be orange (NEC 230.56) |
| Yellow | Switch leg or traveler | N/A | Common for switch loops and 3-way traveler wires (not standardized in NEC) |
| Brown | Hot (high-voltage / sometimes phase) | Brown (L1) | Used in some industrial and high-voltage applications; L1 in IEC systems |
| Purple / Violet | Isolated ground | N/A | Isolated ground conductors may be colored purple per NEC 250.146(D) |
Key Rules to Remember
- White or gray must be used for neutral (grounded) conductors unless re-identified with tape or sleeve at terminations.
- Green, green with yellow stripe, or bare copper is reserved for equipment grounding conductors (EGC) only.
- The high-leg of a 4-wire delta system must be identified in orange (NEC 230.56 and 215.8).
- Conductors larger than 6 AWG do not have standardized insulation colors; they must be identified at each termination point.
3-Phase Color Conventions
In US three-phase systems, black/red/blue is a common convention for phases A/B/C, with white for neutral and green for ground. This is not mandated by the NEC for branch circuits but is widely used for clarity.
In IEC (European) systems, the convention is brown/black/grey for L1/L2/L3, blue for neutral, and green/yellow for ground.