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JIM WISER 05-30-2012 11:58 AM

Identify color of phase?
2011 now requires you identify each phase color? Before i knew the system but now i must buy black, red, blue mc cable?

Jim Port 05-30-2012 12:06 PM

MC is a cable. The conductors will already be identified.

JulieMor 05-30-2012 01:06 PM

I take it you are referring to 210.5(C)
(C) Identification of Ungrounded Conductors. Ungrounded conductors shall be identified in accordance with 210.5(C)(1), (2), and (3).
(1) Application. Where the premises wiring system has branch circuits supplied from more than one nominal voltage system, each ungrounded conductor of a branch circuit shall be identified by phase or line and system at all termination, connection, and splice points.
(2) Means of Identification. The means of identification shall be permitted to be by separate color coding, marking tape, tagging, or other approved means.
(3) Posting of Identification Means. The method utilized for conductors originating within each branch-circuit panelboard or similar branch-circuit distribution equipment shall be documented in a manner that is readily available or shall be permanently posted at each branch-circuit panelboard
or similar branch-circuit distribution equipment.

When you're talking phases, are you referring to a 3-phase system or is this a residential installation? Few homes have three phase services.

There's a lot of confusion about phases. The vast majority of homes have a single phase service. The utility company taps one of their three phase lines and installs a transformer which drops the voltage to 240 like this:

You have two lines coming off that that are 120v each but it's still a single phase service. I would take the code to mean you need a separate color for each line, eg. black for Line 1 and red for line 2.

If you are installing MC or NM cabling, that identification is already done for you, as Jim said.

For as long as I've been working in the trade we have always identified phases black-red-blue for 240v systems and brown-orange-yellow for 480v systems. When I've worked residential I typically use a black-red coding when pulling wire through conduit. If I have more than 2 current carrying conductors in a single conduit, I may pull in other colors to make identification easier for me.

I think that section was added to the code to address color changing that is sometimes done after a conductor leaves the panel. It can be an electrician's nightmare and dangerous for the non-professional.

Techy 05-30-2012 04:27 PM

if you follow 210.5(c) to the letter, yes you would be required to buy Black/white(brown/grey), red/white(Orange/Grey), and blue/white(Yellow/Grey) MC for 120/208v(277/480v) wiring.

Or you can phase tape everywhere. Per 210.5(c)[2]

Some jurisdictions also do not allow orange for anything other than delta high legs, In these cases we use purple or pink for 277/480V 'B'

Jim Port 05-30-2012 04:36 PM

The NEC does not specify that Br/Or/Y is 277/480 or that Bl/r/Blu is 120/240 or 120/208.

If there are different voltage systems they need to be identified on the panels with a color key.

Techy 05-30-2012 04:40 PM

Yes, but 210.5 says you have to pick a color set, post it on every panel, and maintain it throughout the building. My inspectors interpret this to include cable assemblies. So if it's a 'C Phase' Circuit, the wire better be somehow marked 'blue' if that's what's on the panel color key.

Jim Port 05-30-2012 04:48 PM

Agreed, i was just pointing out that the NEC does not mandate a certain color scheme based on voltage. Except for high legs, grounding and neutrals any colors are fair game.

AllanJ 05-30-2012 05:00 PM

As I see it:

Single homes and apartments almost always have just one voltage system, either 120/240 or 120/208, (or in some very old premises, 120 only). The 120/208 is 3 phase and if found in a single home only two of the three phases are typically present.

With just one voltage system it is not mandatory to color code all the branch circuits of each leg or phase.

For example, you might have a multiwire branch circuit (with red and black hot conductors) and you don't have to worry about remarking a black/white 120 volt subcircuit from the red and white conductors at a junction box. (Also, two conductor Romex with red and white conductors is not available.)

JulieMor 05-30-2012 06:32 PM


Originally Posted by Jim Port (Post 932333)
The NEC does not specify that Br/Or/Y is 277/480 or that Bl/r/Blu is 120/240 or 120/208.

Yes, but wouldn't it be nice if they created a standard?

In the Chicago area, we've pretty much adopted the B-R-B, B-O-Y as a standard. Not so long ago the identification was done with tape. Now it's all color coded insulation. The first time I saw brown, orange and yellow 500MCM offloaded on a jobsite it was like seeing a Martian.

Jim Port 05-30-2012 07:32 PM

It might work, but nobody wants your pink switch legs. :no:

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