Technical information

INDUSTRIAL MACHINERY

2.5 Conductor colours

NEC and CEC (and UL508A in the general section) only define the colours for

neutral and equipotential conductors:

7 white or grey:neutral

7 green (green-yellow also allowed): ground connection

All other conductors can be identified with any colour provided that the above

colours are not used.

The NFPA 79 standard for Industrial Machinery (and section 66.9 of UL508A)

specifies cable colour:

7 black:all the rated voltage conductors (both po

w er and control)

7 white or grey:for conductors in alternating current connected to the

grounded circuit (mainly the neutral and the earth side of the AC control

circuits)

7 green:(green-yellow also allowed); ground connection

7 red :AC control circuit with voltage diff erent from the rated one (ungrounded)

7 blue:DC control circuit (ungrounded)

7 blue-white:DC control circuit (grounded)

7 yellow:(orange also allowed ); interlocking circuits powered upstream the

main circuit breaker (grounded)

7 yellow-white:interlocking circuits powered upstream the main circuit breaker

(ungrounded)