Extract from EN 60204-1:2006
13.2 Identification of conductors
13.2.1 General requirements
Each conductor shall be identifiable at each termination in accordance with the technical documentation (see Clause 17).
It is recommended (for example to facilitate maintenance) that conductors be identified by number, alphanumeric, colour (either solid or with one or more stripes), or a combination of colour and numbers or alphanumeric. When numbers are used, they shall be Arabic, letters shall be Roman (either upper or lower case).
NOTE Annex B can be used for agreement between supplier and user regarding a preferred method of identification.
13.2.2 Identification of the protective conductor
The protective conductor shall be readily distinguishable by shape, location, marking, or colour, when identification by colour alone, the bicolour combination GREEN-AND-YELLOW shall be used throughout the length of the conductor. This colour identification is strictly reserved for the protective conductor.
For insulated conductors, the bicolour combination GREEN-AND-YELLOW shall be such that on any 15mm length, one of the colours covers at least 30% and not more than 70% of the surface of the conductor, the other colour covering the remainder of the surface.
Where the protective conductor can be easily identified by its shape, position, or construction (for example a braided conductor, uninsulated stranded conductor), or where the insulated conductor is not readily accessible, colour coding throughout its length is not necessary but the ends or accessible locations shall be clearly identified by the graphical symbol IEC 60417-5019 (DB:2002-10) or by the bicolour combination GRENE-AND-YELLOW.
13.2.3 Identification of the neutral conductor
Where a circuit includes a neutral conductor that is identified by colour alone, the colour used for this conductor shall be BLUE. In order to avoid confusion with other colours, it is recommended that an unsaturated blue be used, called "light blue" (see 3.3.3 of IEC 60446). Where the selected colour is the sole identification of the neutral conductor, that colour shall not be used for identifying any other conductor where confusion is possible.
Where identification by colour is used, bare conductors used as neutral conductors shall be ether coloured by a stripe, 15mm to 100mm wide in each compartment or unit and at each accessible location, or coloured throughout their length.
13.2.4 Identification by colour
Where colour-coding is used for identification of conductors (other than the protective conductor (see 13.2.2)), the following colours may be used
BLACK, BROWN, RED, ORANGE, YELLOW, GREEN, BLUE (including LIGHT BLUE), VIOLET, GREY, WHITE, PINK, TURQUOISE.
NOTE this list of colours is derived from IEC 60757
It is recommended that, where colour is used for identification, the colour be used throughout the length of the conductor either by the colour of the insulation or by colour markers at regular internals and at the ends or accessible location.
For safety reasons, the colour GREEN or the colour YELLOW should not be used where there is a possibility of confusion with the bicolour combination GREEN-AND-YELLOW (see 13.2.2).
Colour identification using combinations of those colours listed above may be used provided there can be no confusion and GREEN-AND-YELLOW is not used except in the bicolour combination GREEN-AND-YELLOW.
Where colour-coding is used for identification of conductors, it is recommended that they be colour-coded as follows;
- BLACK a.c. and d.c. power circuits.
- RED a.c. control circuits.
- BLUE d.c. control circuits.
- ORANGE excepted circuits in accordance with 5.3.5.
Exceptions to the above are permitted where.
- insulation is used that is not available in the colours recommended; or
- multiconductor cable is used, but not the bicolour combination GREEN-AND-YELLOW