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#168797 - 09/15/07 08:11 AM Wire color of Type NM
JoeRossi Offline

Registered: 01/31/03
Posts: 26
Loc: Washington, NJ
Now a day when you buy Type NM #14AWG is white, #12 is yellow, etc. Who made that standard and why. Would love to know. Thanks
Joe Rossi

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#168798 - 09/15/07 08:32 AM Re: Wire color of Type NM [Re: JoeRossi]
HotLine1 Offline


Registered: 04/03/02
Posts: 6791
Loc: Brick, NJ USA
I'm not sure, but I think it's a mfg move. It's a help for us inspectors, and I think some of the EC's like it also.

"Go get the 'yellow' roll"....mech to new helper, as opposed to "read the numbers 12-2" perhaps

#168802 - 09/15/07 10:07 AM Re: Wire color of Type NM [Re: HotLine1]
Rewired Offline

Registered: 01/01/06
Posts: 567
Loc: Hamilton, Ontario, Canada
I have to agree with John.. As far as I know it was so the inspectors could easily identify circuits that are "different" in new construction, as in Blue NM for the arc fault circuits and yellow for the 20A kitchen circuits. Also according to one inspector I talked to and almost got dinged for was to identify voltage! Anything with a red covering contains red and black conductors and is "supposed" to be 240V, no neutral, and explained that its to prevent anyone from thinking the "white is neutral" when in fact it is not such as if you used a regular piece of 2 conductor N.M with black and white conductors on a 240V circuit. That is where I almost got dinged but the inspector "let it go this time" and laughed a bit while saying so!
Years ago I can remember they had plastic sheathed NM in 3-4 colours and even way before that in the days of paper wrapped "loomex" they had what 7 colours that I can think of off the top of my head that were used throughout the years but I think it was only a manufacturing thing back then, the sheath colour meant nothing.

Personally I like the idea of colour coding the cable for the obvious reasons, but it also helps me identify what coils of what cable I have in my van at any given time!


#168803 - 09/15/07 10:09 AM Re: Wire color of Type NM [Re: Rewired]
Theelectrikid Offline

Registered: 04/30/04
Posts: 854
Loc: Levittown, PA
It also helps when you're getting wire cut by the non-English speaking immigrants that work at Home Depot. (At least at mine.)

Ian A.

Edited by Theelectrikid (09/15/07 10:09 AM)
Is there anyone on board who knows how to fly a plane?

#168806 - 09/15/07 12:47 PM Re: Wire color of Type NM [Re: Theelectrikid]
renosteinke Offline
Cat Servant

Registered: 01/22/05
Posts: 5305
Loc: Blue Collar Country
Around 1998, Rex Cauldwell wrote an article for "Fine Homebuilding" magazine about wiring techniques with Romex. As a side note, he showed how he used spray paint to mark the edges on new rolls of Romex, to help his guys grab the right roll from the truck the FIRST time.

Maybe two years later, one cable maker (I think it was Southwire) began to distribute the colored stuff. Other makers quickly followed.

AFAIK, this was a purely voluntary move by the makers, without any code or industry standard to encourage it. I also suspect that there may be some economies involved; adding color makes it easier for the maker to mix in recycled materials.

#168810 - 09/15/07 04:32 PM Re: Wire color of Type NM [Re: renosteinke]
Tom H Offline

Registered: 01/31/05
Posts: 74
Loc: Milford, Ct, USA
Someone told me once that when they made that standars change, that blue was going to be the color of 14-2, I think I even remember seeing that at a trade show once. Obviously that did not happen, but it would be interesting to hear the manufactures perspective on this question

#168812 - 09/15/07 06:50 PM Re: Wire color of Type NM [Re: Tom H]
NORCAL Offline

Registered: 09/25/02
Posts: 805
Just think about some of the ones pulling it, if they were laying sod the crew leader would be yelling "Green side up,green side up".

#168813 - 09/16/07 07:27 AM Re: Wire color of Type NM [Re: JoeRossi]
Sandro Offline

Registered: 12/30/01
Posts: 449
Loc: Stoney Creek, ON, Canada
Now if only they could come up with colour coded armoured (BX) cable.

#168814 - 09/16/07 08:30 AM Re: Wire color of Type NM [Re: Sandro]
electure Offline


Registered: 12/24/00
Posts: 4226
Loc: Fullerton, CA USA
Do you mean like THIS?

AFC's color coded MC and AC cable has been around since before the color coded NM cable

#168891 - 09/19/07 09:11 AM Re: Wire color of Type NM [Re: electure]
pauluk Offline

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
Our equivalent of NM in Britain isn't so colorful.

The old 1950s/60s Imperial-size cables were a case of "you can have any outer sheath color you like so long as it's gray."

I'm not exactly sure when it first appeared, but sometime after the switch to metric sizes in the 1970s manufacturers started offering white sheaths as well. They became quite common during the 1980s, especially for exposed surface runs. The clips were then made in both gray and white versions.

With the recent change to the new European color coding for the internal conductor insulation, the cables are back to being available only with a gray sheath.

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