Single Phase Branch Circuit Conductor Color Code

Dear All,

Our spec indicates that three phase colors for circuits exceeding 200 volts to ground is below:
a. Phase A: Brown.
b. Phase B: Orange.
c. Phase C: Yellow.

But doesn't say anything about single phase branch circuit color. Is there any restriction for color codes for single phase at NEC? Can I use the same colors as single phase? Can I use tapes for color coding?
 

Little Bill

Moderator
Staff member
The only thing the NEC requires a certain color for is orange for a high leg Delta 3ph service. They require the "B" phase to be orange. No other requirements for color coding. Nothing about branch circuits unless it involves the "B" phase. Now there are requirements for identifying conductors for different voltages supplied in the same building, but no colors specified. Yes, you can use tape.
 

Dennis Alwon

Moderator
Staff member
You can use the same colors for the single phase circuits of the system you mentioned. Another system, if there is one, should be color coded differently and a plaque should be left at the services to indicate the system voltages for those colors
 

roger

Moderator
Staff member
The only thing the NEC requires a certain color for is orange for a high leg Delta 3ph service. They require the "B" phase to be orange. No other requirements for color coding. Nothing about branch circuits unless it involves the "B" phase. Now there are requirements for identifying conductors for different voltages supplied in the same building, but no colors specified. Yes, you can use tape.
Well there is 517.160 but that's a special case.

Roger
 

kwired

Electron manager
As others have said NEC only has few specific color requirements for other than grounded/grounding conductors, high leg marking is pretty much the only one that is a general requirement regardless of application. But NEC does require conductors of different voltage systems to be identified by voltage and phase - the method is mostly up to designer/installer though.

If you do have more than one voltage system on the premises I think you would still need to follow whatever identification method you have chosen even on single phase circuits taken from three phase supplies. So if you have typical Brown, Orange, Yellow, Gray for 480/277 and supply a single phase circuit from L1 and L2 you would need to use Brown and Orange for the ungrounded conductors, and gray if a neutral is used.

That is only if insulation color is your identification means, NEC doesn't require you to use that method, just required you have a method. You can use tags, labels, paint, or other methods of ID also.
 

tom baker

First Chief Moderator
Staff member
And light blue is used for IS circuits, going from memory that may be article 505
 

Hv&Lv

Senior Member
The NEC also allows light blue as a neutral in cords 400.22(C).
BTW If anyone on here is designing and specifying international work from the ground up (Airports, Bases etc) just avoid blue altogether.
Just call for brown, your life will be so so much easier. Yep Black - Red - Brown for 208/120.
Or use purple or whatever, just avoid blue.
And call for a green with yellow stripe for ECG's , and no it does not cost more.
This is what any non US sparky is used to:

I’ve done some wiring outside of the US...
brown and blue used to be confusing until I remember blue is cool, so neutral. Brown is what color your underwear will be if you grab it!
 

LarryFine

Master Electrician Electric Contractor Richmond VA
I’ve done some wiring outside of the US...
brown and blue used to be confusing until I remember blue is cool, so neutral. Brown is what color your underwear will be if you grab it!
I always thought the opposite made more sense: blue = sky, brown = earth.
 
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