On the subject of color codes, is there an agreed standard for 3-phase colors in the U.S.?

I've seen them listed variously as black, red, orange and as black, red, blue.

There is no code requiement, other than white or gray must be a grounded conductor & green or green with yellow stripes is a grounding conductor, and orange must be used for the conductor with the higher voltage to ground on certain systems.

There are, however, a few color code schemes that are popular. For 120/208 3 phase- black, red, blue. For 277/480 brown, orange, yellow.

These coloring schemes don't make the system work one bit better. They do make it easier on the installer & anyone that follows him. Nothing worse than opening up a box during a troubleshooting session & finding 20 or 30 conductors, all the same color.

Do you mean as on the older 240V delta system with a mid-point ground that was described to me?

If I interpret this correctly, the two hot legs providing normal 120/240V service could be the usual black and red, but the high leg at 208 to ground would have to be orange in this case?

These coloring schemes don't make the system work one bit better.

Sure it does!!! The Electrons will only flow through a color coded conductor
I am just playing around here - by no means am I flaming you Tom! It's just a joke that I use on the job to see if someone is listening to me or just blowing sunshine up my butt.
Believe it or not, I have gotten a few responses that agreed with the bogus theory...and they were serious!!! Wooo...scarry [Count Floyd - SCTV].
It's funny to see the reaction of people when you throw that one at them! There's this puzzled look and a temporary loss of words, but I clue them into the joke before disaster sets in [disaster= running at mach speed to the owner, informing them of the quack EE / Electrician on their project].

Paul [pauluk]:

As Tom has explained, there's no real color code in the NEC. It only requires Grounded Conductors to be either White or Gray [was "natural gray" in previous versions, but natural gray looks like any old gray to me!],
Equipment Grounding Conductors to be Green, Green w/ yellow threads (yellow stripes) - commonly used for Isolated Grounds, or can be bare [in the nude ].
Lastly, the High Voltage [to ground] line on a 4 wire delta is to be Orange.
Other than the listed Conductors above, the NEC doesn't care if you used a conductor with cute little polka dots on a Black/Pink/Purple Tie Dye colored insulation

There is a "commonly used color code" that's used in the trade, which Tom has described also.
For 1 phase 3 wire [120/240 v 1 ph 3 w], Black would be for Line "A", Red for Line "B", White for the Grounded Neutral.

For 208Y/120 3 phase 4 wire:
Line "A" = Black, "B" = Red, "C" = Blue.
Common / Grounded Conductor = White

For 120/240 3 phase 4 wire Deltas:
[list]

[*] In service equipment: "A" = Black, "B" = Blue, "C" = Orange (the High Voltage Line)

[*] Other than Service equipment, or everywhere else: "A" = Black, "B" = Orange (the High Voltage Line), "C" = Blue.
The Grounded Neutral is White.

For 480Y/277 3 phase 4 wire:
"A" = Brown, "B" = Yellow, "C" = Orange [AKA BOY].
Common / Grounded Conductor is Gray.
**NOTE**
A person in another forum a few years back made a very important point regarding the color coding of "C" on this system, when there's a low voltage SDS on site that is a 4 wire Delta [kind of rare, but not impossible].
The color coded Orange wire would be best suited for the 4 wire Delta's "B" phase, then change the "C" phase on the 480Y/277 system from Orange to Purple.
Right after the person mentioned this, I had some T.I. work in an older Commercial area - which had two Utility services: one 480Y277, the other 120/240 Delta!

Lastly, for 3 phase 3 wire systems:
"A" = Black, "B" = Red, "C" = Blue is the "universal" color code for any voltage.
**BTW** If the system is a "corner grounded" Delta 3 wire [meaning that one line is grounded], the grounded conductor will become White [or gray if there is a SDS which uses a grounded conductor].

Do you mean as on the older 240V delta system with a mid-point ground that was described to me?
If I interpret this correctly, the two hot legs providing normal 120/240V service could be the usual black and red, but the high leg at 208 to ground would have to be orange in this case?

Yes! This is commonly referred to as a "4 wire delta" and is covered in my long winded message above

In a way, it would be a benifit if the Electrons would not flow unless the color code was proper! How many of you guys out there have seen 120 VAC stuff connected to the wild phase? Seen it a bunch of times. All the smoke had left the equipment.
One recent event was at the place my Wife works. They had someone install a 4 plex receptacle on a dedicated circuit to run a Christmas tree flocking machine. After the 4th motor had been fried, they asked me to check it out.
It was a no-brainer; right outside the driveway is the pole with the transformer bank on it. Two small pots on the outside, one large center pot. Secondaries connected in Parallel. Service feeders [Underground] ID labels match on both ends - riser at the pole, plus at the main service.
Mr. Wiggy popped down close to the "240" volt mark when I checked L-N and L-G at the 4 plex receptacle.
Same at the subpanel .

So I moved the breaker down one space, filled the hole with a fillerplate painted Orange, went home and printed some "Danger-208 VAC to ground" labels, labeled the subpanels and fixed the "problem"
I charged $50 for this, which was more than it should have been - but they were going to pay $200 and be happy with that! I just felt bad for them having to buy 4 motors and not having a clue to why they burned out so fast.
Heck, I was going to do the work for free! They insisted on paying.

Scott SET

Thanks for all the info guys. Sorry to grill you all on this one, but when I was in the States I only studied residential 120/240V service in detail, so I wasn't familiar with common 3-ph. practice over there.

All of our LV 3-phase in the U.K. is 4-wire 240/415V Y without any oddball systems like corner-grounded delta or 4-wire delta (no offense intended!).

I hadn't realized that it's usual to use different colors for 277/480 than for 120/208, but if both systems are often present in the same building I can certainly see how it makes sense.

I knew the NEC allows gray as an alternative to white for neutrals, but again I didn't realize that gray would be chosen for the higher voltage system where white is already in use for a lower voltage. (I figured it was just a little-used option reserved for neutrals because white could soon look like gray in some environments!)

Some more questions posed by your answer:

What exactly does SDS stand for? Supply Distribution System is all I can think of that seems appropriate to the context.

On the 4-wire delta systems, why is the high-line defined as phase C in service equipment and phase B elsewhere? Come to that, what exactly do you define as "service" equipment?

(Maybe Oscar Wilde wasn't too far wrong when he described America & Britain as two countries divided by a common language!)

I've also seen references to an industrial 347/600V system. Anyone care to comment?

As for electrons only working through the right color wires, try convincing someone that holding a cord up high will slow down the electrons because they have to go uphill.....!!

One of the radio stations around here had an April Fools' bit (Day for Joking) that told everyone to unplug their Telephones because the Utility was going to be cleaning out their lines.
They had people calling up the Radio Station from cell phones asking if it they had to cover up Bird Cages and Furniture near the Telephone Jacks and if it was safe to plug the Phone back in yet! It was Great!!

Anyway, Just to show you how much We all think alike here (US) Our generally accepted 120/208Y Colors Here (Long Island, NY) are:
Blue, Black, Red (same general phase order)

Bill

Hi Paul,
What exactly does SDS stand for

Well it's supposed to stand for 'Seperatly Derived Systems' , which by NEC's definitions is something that creates a nuetral, as an X-former or Generator.

As with many of our NEC definitions, there are plenty of gray area's to dwell on.

On the 4-wire delta systems, why is the high-line defined as phase C in service equipment and phase B elsewhere? Come to that, what exactly do you define as "service" equipment?

hmmm, how does one nicely explain how our definitions go in circles ?
The 'Utility' and the NEC do not always see eye to eye, and many times make conflicting rules, as in the high-leg of a delta.

'Servive equipment' would be the main panel, shutoff , T-switch, whatever is first on the load end of the utilities incomming service entrance wires.

As long as I can remember, it's been trade practice to use the BOY for 480 systems. Over the last few years (in Texas anyway) many contractors are using Brown-Purple-Yellow. This change came about due to the NEC requirement for only "High Legs" on deltas being color coded orange. Just thought I would pass along some info. Tom

yup, we've even got purple tape !
only in America!

TMON,

I've been using the brown, yellow & purple myself for some time. It might avoid the confusion if there is also a lower voltage system on the premises.

I wish someone would figure out how to keep electricity from flowing through a green colored wire (except under fault conditions) I've lost count of how many times I've found green to be one leg of a 480 system. Like one of my buddies sez "electricity don't care what color the insulation is."

At the power plant up the road from me, the hot conductors are black, red and white, NEC does not apply in this case. This scheme also seems popular at aboveground facilities of coal mines where the NEC is supposed to apply.

[This message has been edited by Tom (edited 08-20-2001).]

I went to a house a couple of weeks ago to investigate problems with an extended light & ceiling fan circuit. I found that the previous "electrician" apparently only had one type of wire - a single cable (i.e. for onduiit use) in red.

Apart from single cables draped everywhere across the attic, it was fun trying to work out which reds were hot and which were neutral. He'd even used red for grounds, noth that it mattered much, because he'd carefully linked the fan and accessory boxes together, but not actually connected any of this wiring to a ground!

I only went there for a 20 minute job.....

Sparky,
A SDS has nothing to do with creating a neutral. You can have SDS systems without neutrals. A SDS is a power source that does not share a circuit conductor with any other power source. A transformer is a SDS because there is no physical connection between the primary and secondary circuit conductors. An autotransformer is not a SDS because there is a conductor common to both the primary and secondary side of the transformer.
Don(resqcapt19)

Another color code question that's just occurred to me:

When you run a single-phase 120V branch from a single-pole C/B at a 120/208 3-phase panel, do you always use black for the hot or do you match it with the appropriate phase color? (Im talking conduit systems; I assume if the 120V branch were Romex it would pretty much have to be black.)

How about a single-phase 277V branch run from a 277/480V panel? Brown & gray? Matched to the brown, yellow, orange (or purple!) phase?

When we run a 1-ph. 240V branch from a 3-ph. 240/415V panel, the hot is always red, even if the breaker is on the yellow or blue phase.

>do you ... use black for the hot
Yes. Color matters only when all three phases are being used.

In a way, it would be pointless to try to match these up by color since the breaker might move tomorrow when the load is redistributed and the color would be wrong.

I figured that probably was the case (like here), but it just crossed my mind that you might do it the other way.

So what about 1-ph 277V from a 277/480 panel? Brown & gray, or back to plain old black for the hot?

I just wondered if any of the other Canadians caught the phasing of a 3 phase 120/208 volt system? In Canada we use:
Phase A-Red
Phase B-Black
Phase C-Blue
Sorry just though there'd ever be a difference between us and the US because so much of our equipment is American made.