Three-phase systems use three hot conductors labeled L1, L2, and L3. The color of these wires depends on regional electrical standards. In common practice, the colors shown below are used, but always verify with local codes and device labeling.
United States and Canada (three-phase color conventions)
In North American installations, the three hot conductors are typically colored black, red, and blue for L1, L2, and L3 respectively. The neutral conductor is white, and the equipment ground is green or bare.
- L1: Black
- L2: Red
- L3: Blue
These colors are standard for most three-phase circuits in commercial and industrial wiring, though some legacy installations may differ. Always check the device labeling and applicable codes before wiring.
European and international codes (IEC 60309 / IEC standards)
Under IEC standards used across Europe and many other regions, the three hot conductors are typically brown, black, and grey for L1, L2, and L3. The neutral is blue, and earth/ground is green-yellow. Older European installations commonly used red, yellow, and blue for L1-L3.
- L1: Brown
- L2: Black
- L3: Grey
Note that many UK and other jurisdictions have transitioned from the old red/yellow/blue scheme to brown/black/grey in new installations. Always rely on device markings and current local codes.
Safety and verification considerations
Because color coding varies by region and specific installation, never assume—verify each time. Use the equipment’s nameplate, wiring diagram, or a licensed electrician to confirm the correct L1/L2/L3 identifications before handling or wiring live circuits.
Common exceptions and practical tips
Industrial environments may feature manufacturer-specific conventions or nonstandard color schemes. When using connectors like IEC 60309, the color of the cable may not always indicate the phase; refer to the connector’s pinout and the equipment labels for accurate identification.
Summary: L1, L2, and L3 are the three hot wires in a three-phase system. Typical color mappings are US/Canada—L1 Black, L2 Red, L3 Blue; Europe/IEC—L1 Brown, L2 Black, L3 Grey (older European codes used Red/Yellow/Blue). Always check local codes and device labeling to confirm.