Color coding wires

[sybrandy]

I understand that when there is a control enclosure that has a means of disconnecting the power supplied to it, that all wires terminating in the enclosure that remain energized, must be yellow. I cannot find this in the NEC and would like confirmation. Thanks

 

[raider1]

This sounds like it might be a requirement from a product standard. There is no NEC requirment that I am aware of that would require what you discribed.

Chris

 

[John Valdes]

No such NEC rule. Some control panel wires are one color. But must be clearly marked. Color coding control panels is not feasable as you have many conductors doing different things. I don't even use white for all the common wires. Usually I use black for power conductors, blue for DC and any other color I want except white or green for AC control.
The key to a well designed control panel is marking of the conductors and a good schematic to follow. Any changes made to the control scheme must be recorded on the master control drawing and updated on panel located drawings. It's also a good idea to initial any changes in case someone needs clarification. Pink anyone?

 

[KentAT]

What is the purpose of the control enclosure?

If it is for control of industrial machinery, NFPA 79, Electrical Standard for
Industrial Machinery, 2007 Edition, does have color codes listed in 13.2. I also thought yellow was the color for what you described, but for that standard the color is orange.

For industrial control panels, UL508A is the standard. My understanding is that there is a table/section in there 66.9 which has their color coding scheme.

This is from a thread I saved from another forum since I don't have access to UL508A:

UL-508A Manual section 66.9 gives a color code for internal control wiring.
It is as follows:
a) Black - all ungrounded control circuit conductors operating at the supply
voltage.
b) Red - ungrounded ac control circuits operating at a voltage less than the
supply voltage.
c) Blue - ungrounded dc control circuits.
d) Yellow - ungrounded control circuits or other wiring, such as for cabinet
lighting, that remain energized when the main disconnect is in the "off"
position.
e) White or natural gray - grounded ac current carrying control circuit
conductor regardless of voltage.'
f) White with blue stripe - grounded dc current carrying control circuit
conductor.
g) White with yellow stripe - grounded ac control circuit current carrying
conductor that remains energized when the main disconnect switch is in the
"off" position.
Exception: Leads on assembled components, multiconductor cable, leads
used to connect electronic devices, and conductor sizes 20-30 AWG are not
required to comply with this requirement.​

 

[billsnuff]

example

example

<600VAC, >120VAC Black (3 ph 480) with phase marking.
120VAC control circuit Red
24VDC +blue - blue w/white stirpe
24VDC E-Stop purple

just part of the std for our location.