Wire color of High Leg in a Delta circuit

What is the US standard color coding of the high leg and other phases in a delta circuit? TIA

This is what I have:

277/480 Volt AC Wire Colors
Phase 1 - Brown
Phase 2 - Orange High Leg
Phase 3 - Yellow
Neutral - Gray
Ground - Green, Green with Yellow Stripe, or Bare Wire

Regards,

[110.15] states that it must be orange, since the 2002 revision

This is not 277/480V. It is a rather unconventional high leg configuration typically used with 240V delta but rarely with 480V delta.

While it clearly can be done, I'm hot sure just what would motivate such a configuration. I'm not even sure it is "legal". It places upon the high leg a voltage to ground which is far higher (somewhere around 390VAC) than the normal 277VAC.

I suppose it is legal since there are 480V delta systems out there which are corner grounded placing 480VAC to ground on the two ungrounded phases.

But why? It makes the power network needlessly hazardous both in terms of service personnel and phase-to-ground insulation in connected equipment.

No VFD with a CE label will tolerate either corner ground or high leg as above. The CE noise suppression circuitry must be disconnected first which is unfortunate and in some countries, illegal.

Dick,
It's an outlier for sure, but I've seen it. In fact I rented a building with that configuration once in Seattle, it was a PITA because of some of the issues you mentioned. Ours was an open delta to boot, so there were two different transformers on the pole, a 480 secondary single phase and a 480/240 secondary single phase, so in our case, A was the high leg, because the single voltage transformer was connected A-B, the split phase was B to C. So phase to phase was 480V, B or C to neutral was 240V and A to Neutral (or ground) was 415V and thereby unusable. It had been special ordered by a previous tenant who was making printed circuit boards. All we could imagine was that maybe they needed a lot of 240V single phase power for something and didn't want two transformers. Otherwise you're right, it makes little sense.

We ended up calling the utility and having them swap it out for a standard 480/277Y transformer. They did it, then wanted to know if we wanted to keep the old transformers there "just in case", because they were not their standard and had no use for them. We said sure, then after they left we sold them for scrap ;-)

But back to the OP, yes, it is supposed to be marked orange per NEC 110.15, which doesn't specify any voltage; "only the conductor or bus bar having the higher phase voltage to ground shall be durably and permanently marked by an outer finish that is orange in color or by other effective means". However there are some jurisdictions in which local codes have modified that because of pre-existing standards they had prior to 2002. So purple is another color I have seen used.

Lastly, power utilities often have their own standards and they are not required to follow the NEC, which confuses a lot of people. The NEC has to do with how it is marked AFTER the service entrance.

Well, that is interesting. The longer you hang around this business, the stranger it seems to get!

As I'm sure you know from my earlier posts, I am no fan of floating or assymetric grounded systems. In my view they should be outlawed due to the increased hazards associated with them. But, of course, that's not going to happen.

Just as an illustration of added hazards, I was called into an automotive plant near Detroit some years ago to determine why they were experiencing frequent catastrophic large VFD failures. As with almost all automotive plants, this was a floating 480V delta. After two weeks of running a recorder phase to ground on their system, I was able to show the plant engineer that his "safe" power system had floated to 800VDC above ground at one point and to 1575VAC at another point! Yes, his maintenance people all had "safe" CAT III 1000VAC meters. And, of course, the VFD's didn't like it much either.

In typical automotive fashion, rather than find the sources of the high voltages, they installed delta/wye drive isolation transformers. This solved the drive failure problem but left the personnel hazard issue in place. That seemed ok to them and it is operating that way to this day.