UL 508a question

[petersonra]

It has been brought to my attention that the color coding for control circuit wiring in UL508a is only found in the section of additional requirements for controls panels used for industrial machinery.

It therefore appears to me that this color code does not apply to UL listed control panels for other than industrial machines.

I still think green is reserved and required for EGC and white for grounded conductors per paragraph 17, but other conductors can be whatever.

Any comments?

Jraef?

 

[Jraef]

It has been brought to my attention that the color coding for control circuit wiring in UL508a is only found in the section of additional requirements for controls panels used for industrial machinery.

It therefore appears to me that this color code does not apply to UL listed control panels for other than industrial machines.

I still think green is reserved and required for EGC and white for grounded conductors per paragraph 17, but other conductors can be whatever.

Any comments?

Jraef?

Bob,
The official sub-title for UL 508a is "Industrial Control Panels". So really, the first statement someone made to you is immediately a moot point. There is no part of UL 508a that is NOT pertaining to "industrial controls". Colors are delineated in 66.5.3 then reiterated and expanded on in 66.9, I see no ambiguity. Maybe whomever made that comment to you was looking at 66.9 and saw, at the top of the page, the words "Industrial Control Panels" and ASSumed that this was a "section of additional requirements", but if you look, EVERY page says that at the top! Years ago after the old JIC standards were co-opted by NFPA 79, UL 508a only had what is now 66.5.3, which simply said that power circuits were to be black, grounded power or control was to be white, and of course, 17, which was about insulated ground wires. So back then UL allowed colors to be whatever, as long as you reserved black, white and green as specified. I'm not sure when it happened, but some time ago UL 508a added what is now 66.9, which is almost the exact same wording as what is in NFPA 79, I think because there was some ambiguity not in what NFPA 79 said or required, but in whether or not it was an "enforceable" standard or just a "reference" standard. By UL508a adopting the same requirements, it didn't matter (assuming NRTL listing is codified).

The other possibility is that they were thinking of the NEC article 409, which DOES apply only to "industrial control panels". But there is nothing in 409 about wire colors.

 

[petersonra]

All of UL508a is about industrial control panels.

Paragraphs 65-67 only cover ICP being used on industrial machines.

 

[Jraef]

Huh, never even noticed that...

65.1 These requirements cover industrial control panels for industrial machinery (NFPA 79-1994,
Electrical Standard for Industrial Machinery).

That explains then why the wording is exactly the same as NFPA 79...

So that then implies you can have an "industrial control panel" that is for "non-industrial" machinery then? What would that be? Farm equipment? Residential? I don't get it. Funny how people love to parse things out to the nth degree sometimes. I guess I never bothered with a distinction, I just accepted that any control panel I was building was for "industrial machinery".

 

[jim dungar]

Huh, never even noticed that...



That explains then why the wording is exactly the same as NFPA 79...

So that then implies you can have an "industrial control panel" that is for "non-industrial" machinery then? What would that be? Farm equipment? Residential? I don't get it. Funny how people love to parse things out to the nth degree sometimes. I guess I never bothered with a distinction, I just accepted that any control panel I was building was for "industrial machinery".

An industrial control panel could be for a process involving multiple machines, while a machine control panel is likely associated with a single machine. But I believe that UL508 addresses panels on specific types of industrial machinery.