Color Codes
Conductors of a three-phase system are usually identified by a color code, to allow for balanced loading and to assure the correct phase rotation for induction motors. Colors used may adhere to International Standard IEC 60446, older standards or to no standard at all and may vary even within a single installation. For example, in the U.S. and Canada, different color codes are used for grounded (earthed) and ungrounded systems.
| L1 | L2 | L3 | Neutral | Ground/ protective earth |
|
|---|---|---|---|---|---|
| Australia and New Zealand as per AS/NZS 3000:2007 Figure 3.2 (or as per IEC 60446 as approved by AS:3000) | Red (or brown)1 | White (or black)1 (prev. yellow) | Dark blue (or grey)1 | Black (or blue)1 | Green/yellow striped (green on very old installations) |
| Canada (mandatory) | Red | Black | Blue | White | Green or bare copper |
| Canada (isolated three-phase installations) | Orange | Brown | Yellow | White | Green |
| European Union and all countries who use European CENELEC standards April 2004 (IEC 60446), Hong Kong from July 2007, Singapore from March 2009 | Brown | Black | Grey | Blue | Green/yellow striped2 |
| Older European (IEC 60446, varies by country3) | Black or brown | Black or brown | Black or brown | Blue | Green/yellow striped3 |
| UK until April 2006, Hong Kong until April 2009, South Africa, Malaysia, Singapore until February 2011 | Red | Yellow | Blue | Black | Green/yellow striped (green on installations before c. 1970) |
| Republic of India and Pakistan | Red | Yellow | Blue | Black | Green |
| Former USSR (Russia, Ukraine, Kazakhstan) and People's Republic of China (per GB 50303-2002 Section 15.2.2) | Yellow | Green | Red | Light blue | Green/yellow striped |
| Norway | Black | White/Grey | Brown | Blue | Yellow/green striped, older may be only yellow or bare copper |
| United States (common practice)4 | Black | Red | Blue | White, or grey | Green, green/yellow striped,7 or a bare copper wire |
| United States (alternative practice)5 | Brown | Orange (delta), violet (wye) | Yellow | Grey, or white | Green |
- ^1 In Australia and New Zealand, active conductors can be any color except green/yellow, green, yellow, black or light blue. Yellow is no longer permitted in the 2007 revision of wiring code ASNZS 3000. European color codes are used for all IEC or flex cables such as extension leads, appliance leads etc. and are equally permitted for use in building wiring per AS/NZS 3000:2007.
- ^2 The international standard green-yellow marking of protective-earth conductors was introduced to reduce the risk of confusion by color blind installers. About 7% to 10% of men cannot clearly distinguish between red and green, which is a particular concern in older schemes where red marks a live conductor and green marks protective earth or safety ground.
- ^3 In Europe, there still exist installations with older colors for protective earth but, since the early 1970s, all new installations use green/yellow according to IEC 60446.
- ^4 See Paul Cook: Harmonised colours and alphanumeric marking. IEE Wiring Matters, Spring 2006.
- ^5 Since 1975, the U.S. National Electric Code has not specified coloring of phase conductors. It is common practice in many regions to identify 120/208Y conductors as black, red, and blue. Local regulations may amend the N.E.C. The U.S. National Electric Code has color requirements for grounded conductors, ground and grounded-delta 3-phase systems which result in one ungrounded leg having a higher voltage potential to ground than the other two ungrounded legs. Orange is only appropriate when the system has a grounded delta service, regardless of voltage.
- ^6 The U.S. National Electric Code does not specify coloring of phase conductors, other than orange for grounded delta. It is common practice in many regions to identify 277/480Y conductors as brown, orange and yellow (delta) or brown, violet and yellow (wye), with orange always being the center phase. Local practice may amend the N.E.C. The US N.E.C. rule 517.160 (5) states these colors are to be used for isolated power systems in health care facilities. Color of conductors does not identify voltage of a circuit, because there is no formal standard.
- ^7 In the U.S., a green/yellow striped wire may indicate an isolated ground. In most countries today, green/yellow striped wire may only be used for protective earth (safety ground) and may never be unconnected or used for any other purpose.
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