277 volts Lighting

[kevinware]

Last night in my electrical class my instructor stated that in a 480/277v lighting system it was an NEC violation to use a white wire as a neutral and that I was suppose to use a gray wire all the way to the fixture. I understand the use of brown, orange, yellow for the courtesy factor. But I looked all through article 200 and all I find is the reference to the use of white or gray conductor.

200.6(A)
An insulated grounded conductor of 6 AWG or smaller shall be identified by a continuous white or gray outer finish or by three continuous white stripes on other than green insulation along its entire length.

I only see a change when I come to 200.6(D)
Where conductors of different systems are installed in the same raceway, cable, box, auxiliary gutter, or other type of enclosure, one system grounded conductor, if required, shall have an outer covering conforming to 200.6(A) or 200.6(B). Each other system grounded conductor shall have an outer covering of white with a readily distinguishable , different colored stripe other than green running along the insulation, or shall have other different means of identification as allowed by 200.6(A) or 200.6(B) that will distinguish each system grounded conductor.

So if I use a white conductor, not a gray conductor, as my neutral in a 480/277V lighting system is that an NEC violation or is it a courtesy violation???????

Thanks for all your help, I learn so much from this site.
Kevin

[ March 29, 2005, 12:20 PM: Message edited by: kevinware ]

 

[wwebb]

Re: 277 volts Lighting

The way I see it is that your instructor has fallen victim to the same thing a lot of us do.....habit. Most electricians use the gray out of habit, but it is NOT a code requirement. It can be either, as you have deduced.

 

[tom baker]

Re: 277 volts Lighting

You are correct.
It can be white or gray. If a second grounded condutor is present then it is white with a stripe not green.
In the 1999 NEC a gray wire was a ungrounded conductor.
In the 2002 NEC a gray wire becomes a grounded conductor.

 

[celtic]

Re: 277 volts Lighting

It would depend on what color the other systems are...if the 120 was grey, the 277 couldn't be grey!
I see it as a trick question, to see if the class is learning what was taught or just remembering what was said.
Even the colors of the phases is not written in stone. While Blk/Red/Bl is common for 120v and B/O/Y is common for 277v systems - it can be overridden by existing identifications.
I had the opportunity to do some site lighting/roadway work on the NJ Turnpike, Rt78, Rts 1&9, Rt 22, Rt 21, etc The lighting feeds were 480v...guess what colors were used? Here's a hint ~ it wasn't B/O/Y.

 

[tkb]

Re: 277 volts Lighting

grey, white, green

 

[infinity]

Re: 277 volts Lighting

It would depend on what color the other systems are...if the 120 was grey, the 277 couldn't be grey!

I would disagree that if one system were white the other would have to be grey. This would only apply if the two systems were in the same raceway, cable, box, auxillary gutter, or other type of enclosure. If the two systems were keep completely separate from each other than the grounded conductors could be either or both colors. See 200.6(D)

 

[pierre]

Re: 277 volts Lighting

This is new to the 2005 NEC, but it is important. It used to pertain strictly to multiwire systems, but now it pertains to premises wiring systems.


"210.5(C).Ungrounded Conductors.
Where the premises wiring system has branch circuits supplied from more than one nominal voltage system, each ungrounded conductor of a branch circuit, where accessible, shall be identified by system, The means of identification shall be permitted to be by separate color coding, marking tape, tagging, or other approved means and shall be permanently posted at each branch-circuit panelboard or similar branch-circuit distribution equipment."

Regardless of the installation procedure, the ungrounded conductors will required to be identified and posted as such in each panel/equipment location. This is not something I see now, so this will have an effect on future wiring or wiring for those who are now following the '05.
Some buildings I inspect can have many, many panels....

 

[infinity]

Re: 277 volts Lighting

Pierre,

Doesn't 210.5(C) refer only to the ungrounded conductors of different systems. Wouldn't 200.6(D) still apply to the grounded conductors which would allow the grounded conductors of either system to be white, grey or both if they are not installed together in a box, cabinet raceway, etc.?

 

[pierre]

Re: 277 volts Lighting

Infinity
Yes, you are correct. I added that post for informational purposes only (the topic is similar in nature to your post) - as the info I posted is new to the 05 NEC and will make some differences in installation procedures.