IEC 60446. The international standard IEC 60446  Basic and safety principles for man-machine interface, marking and identification - Identification of equipment terminals, conductor terminations and conductors was a standard published by the International Electrotechnical Commission (IEC) that defined basic safety principles for identifying electrical conductors by colours or numerals, for example in electricity distribution wiring.  The standard has been withdrawn; the fourth edition (IEC 60446:2007) was merged in 2010 into the fifth edition of IEC 60445 along with the fourth edition, IEC 60445:2006.

Permitted colours 
The standard permits the following colours for identifying conductors:

 Black 
 Brown 
 Red 
 Orange 
 Yellow 
 Green 
 Blue 
 Violet 
 Grey 
 White 
 Pink 
 Turquoise 

The colours green and yellow on their own are only permitted where confusion with the colouring of the green/yellow protective conductor is unlikely. Combinations of the above colours are permitted, but green and yellow should not be used in any of these combinations other than as green/yellow for the protective conductor.

Use of colours

Neutral or mid-point conductor 
If a circuit includes a neutral or midpoint conductor, then it should be identified by a blue  colour (preferably light blue ). Light blue is the colour used to identify intrinsically safe conductors, and must not be used for any other type of conductor.

AC phase conductors 
The preferred colours for AC phase conductors are:
 L1: Brown 
 L2: Black 
 L3: Grey 
For a single AC phase: brown

Protective conductor 
The colour combination green/yellow  is always and exclusively used to identify the protective conductor. On any 15 mm length of the conductor, one of these two colours should cover between 30% and 70% of the area and the other the remaining area.

Protective earth and neutral (PEN) conductor 
Insulated PEN conductors (combined protective earth + neutral in TN–C systems) should be marked:
 either green/yellow  along their entire length with light blue markings at their ends,
 or light blue  along their entire length with green/yellow markings at the ends.
The cable must have a cross sectional area of 16 mm (5 AWG) or greater.

United States, Canada and Japan 
The three countries United States, Canada and Japan are mentioned in a note in the standard for using different colours:
 White  or natural grey  for mid-wire or neutral conductor (instead of light blue )
 Green  for the protective conductor (instead of green/yellow )

United Kingdom 
British Standard BS 7671:2001 Amendment No 2:2004 adopted the IEC 60446 colours for fixed wiring in the United Kingdom , with the extension that grey  can also be used for line conductors, such that three colours are available for three-phase installations. This extension is expected to be adopted across Europe and may even find its way into a future revision of IEC 60446.

Marking 
Where conductors are in addition identified by letters and numbers, then:
 letters to be used come from Latin character set,
 numbers must be written in Arabic numerals, digits 6 and 9 must be underlined ( and ),
 and a few symbols like + and − can be used.
Green-and-yellow conductors must not be marked.

Examples: L1, L2, L3, N, L+, L−, M, 35, 1

References

External links 
 IEC 60446:2007: Basic and safety principles for man-machine interface, marking and identification – Identification of conductors by colours or numerals, International Electrotechnical Commission, Geneva.
 IEC 60445:2010: Basic and safety principles for man-machine interface, marking and identification - Identification of equipment terminals, conductor terminations and conductors, International Electrotechnical Commission, Geneva.
 Paul Cook: Harmonised colours and alphanumeric marking. IEE Wiring Matters, Spring 2006.
 

60446
Electrical wiring