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Gray as hot conductor? #82697
12/08/02 10:27 AM
12/08/02 10:27 AM
pauluk  Offline OP
Joined: Aug 2001
Posts: 7,520
Norfolk, England
I'm looking at 200.7 of the '02 code, relating to the identification of grounded counductors.

There's an FPN at the end of this section:

FPN: The color gray may have been used in the past as an ungrounded conductor. Care should be taken when working on existing systems.

So when did the NEC first specify that gray be reserved for neutral along with white?

I believe you've all said that the BOY system (with gray for neutral) has been in common use for 277/480 for at least 30 years, so I assume that we're going back a fair way.

[This message has been edited by pauluk (edited 12-08-2002).]

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Re: Gray as hot conductor? #82698
12/08/02 11:47 AM
12/08/02 11:47 AM
resqcapt19  Offline
Joined: Nov 2000
Posts: 2,148
Actually this change was made in the 2002 code. Prior to that the code used the words "natural gray". This is an old term from the early years of thermoplastic insulations and was a "natural" color, that is colorants were not added when the insulating material was made. "Natural gray" has not been available for 30 to 40 years. The use of wire with a gray insulation as a grounded conductor prior to the '02 code was actually a code violation, even though it was also a very common practice. There have been atempts to make this code change in 3 or 4 code cycles prior to the '02 but they were not accepted. All of these proposals cited the common practice of using the manufactured color gray in place of the required "natural gray", but it wasn't until the '02 that a proposal was accepted. The fine print note was added because, even though it was common practice to use the manufactured color gray for the grounded conductor, this color was permitted to be used as a hot conductor. Just another reason why we should never rely on wire colors to determine the voltage and function of a conductor.

Re: Gray as hot conductor? #82699
12/08/02 12:51 PM
12/08/02 12:51 PM
CTwireman  Offline
Joined: Feb 2002
Posts: 840
Connecticut, USA
Just another reason why we should never rely on wire colors to determine the voltage and function of a conductor.

That bears repeating. Everyone has a horror story relating to mis-use of colors!

Re: Gray as hot conductor? #82700
12/08/02 05:57 PM
12/08/02 05:57 PM
sparky806  Offline
Joined: Dec 2002
Posts: 59
Shawnee, KS, USA
Here in my area, Kansas City, grey is commonly used as the "B" phase on a 240 volt grounded B system. Although this is a 3 phase system, it is normally installed with single phase equipment. It can really confuse the newer guys when they see 240 volts from hot to "nuetral".

Re: Gray as hot conductor? #82701
12/08/02 08:41 PM
12/08/02 08:41 PM
Gwz  Offline
Joined: Apr 2002
Posts: 197
The single phase equipment used on the grounded 240V 3Ø 3W system should be indentified by the equipment manufacturer as be 'suitable for use' on a Grounded 3Ø 3W system.

Re: Gray as hot conductor? #82702
12/09/02 07:03 PM
12/09/02 07:03 PM
pauluk  Offline OP
Joined: Aug 2001
Posts: 7,520
Norfolk, England
Ah, natural gray.... I recall some discussions about this change of terminology from some months ago now.

I've since noticed a similar FPN on some other NEC articles, all with the bar at the side to indicate new or altered entries.


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