I've worked as an industrial electrician in several facilities across the U.S. I'm not sure if it's a code requirement, but the standard insulation color for DC wiring always seems to be blue...in just about every plant I've ever worked in. I KNOW it's a Proctor and Gamble Spec...
Machine Builders and Industrial Electrical standard insulation Wire Color code for most Industrial Plants.
Blue = dc control wire (24vdc) to (120vdc).
Yellow = 120 vac from an outside power source.
Red - 120 vac control cicuit.
Black = 120 vac (x1) Hot wire or 220 vac
White = 120 vac netural wire (x2)
Green = ground wire
(x1)is the black and (x2)white wires on the output side of an Control transformer.
IEC for 120 vac
Brown = 24 to 120 vac Hot wire
Blue = 24 to 120 vac Netural wire
Green/Yellow Strip = Ground wire
Black = 3 phase motor wiring.
For 3 phase Motor starter (L1-L2-L3) Line source
(T1-T2-T3) Load side to Motor
For 3 Phase Rotation or (phasing) A= Red B=Black C= white
I recommend you check out IEC 60204-1:2000, clause 14.2 through 14.2.4, it identifies color codes for machinery. Christopher Caserta
ccaserta@us.tuv.com
Ph:904-225-0360
The color codes for AC wiring that connects to Line power conflict with color codes used internally in modern equipment. Additionally the Black/White of USA color codes is Brown/Blue in the rest of the world.
The original IBM PC-XT had a 12 pin Molex connector using the following color code: Gnd-Black, +5 v red, -5 v white, +12 v yellow, -12 v blue.
The National Electrical Code (NEC) mandates green or green with yellow stripes or bare wire for ground connections, but assumes that you are truly connecting to ground, not "merely" chassis common. And we are not speaking about DC or analog or digital ground, as used in current discussions and sketches, but the ground that eventually connects to a copper plated rod sunk into the earth of your facility, your safety ground. The ground that is so low impedance that your protection devices will not fail do to a poor complete circuit to ground.
By the way, as far as line power connections go, what we used to call "hot" is now called "ungrounded", what used to be "neutral" is now "grounding", and "ground" is now called the "grounded" conductor.
Do what I am currently obliged to do: use one color of wire for everything, which forces the technicians to use service drawings if they are servicing the equipment. And not make mistakes based on memory.
Solaris,
NFPA 79 governs industrial machinery and it specifies color codes but they may not apply to your specific application...Here are some color codes you will find in NFPA 79 chapter 14.2:
ungrounded DC control conductors - blue
grounded DC control conductors - white with blue trace