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#80785 05/22/02 10:49 AM
Joined: Feb 2002
Posts: 183
n1ist Offline OP
For some strange reason, I have been tasked to solve a 3-phase problem here at work (in real life, I'm a software guy :-)

We build test equipment that runs on 3-phase wye AC. This equipment is supplied without a linecord; it is up to our customers to wire it in to their plant power correctly. There is a primary AC box that contains a 3-phase breaker that is wired to a barrier strip. The other side of this barrier strip is wired to a power distribution unit (containing a tapped isolation transformer, emergency off contactors, a 3-phase rotation sensor and secondary breakers). For reasons beyond our control, the pigtail on the PDU is wired with L1 being black, L2 being blue, and L3 being black, and this can't be changed. At the barrier strip, this gets changed to black red blue so people wiring up the incoming AC line just have to match up colors (yep, the breaker is also labelled L1 L2 L3). Now I just found out that this system is also shipped for other voltages. Should we use brown orange yellow wiring from the barrier strip to the breaker for 480V? What should we use for the other voltages? We offer this for 208, 240, 277,380, 415, and 480V 3-phase.
This system is used world-wide so whatever we do must be acceptable to both NEC and TUV.


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Joined: Feb 2002
Posts: 183
n1ist Offline OP
Another thought just hit me - is it legal to just run 3 black wires from the barrier strip to the breaker and rely on the L1 L2 L3 labeling to ensure that the incoming power gets connected correctly? That way, there is no voltage-dependant color code issues to deal with.

Joined: Feb 2001
Posts: 159
CRW Offline
The NEC doesn't specify 3 phase color codes, just that you use a consistent code(and post it) in a building to identify different system voltages. And for the equipment you are building, your idea of using L1 L2 L3 labeling sounds good. This would be a better idea, since black-red-blue and brown-orange-yellow while common are not universal.

Joined: Aug 2001
Posts: 7,520

I see you are supplying a 415V version, which I assume is for export to the U.K. and/or other British-influenced countries.

As far as it goes here in Britain, the wiring between breaker and barrier strip would be considered part of your equipment rather than wiring in the building, and you can use any colors you wish.

Standard building-wire phase colors here are red/yellow/blue, and almost anyone hooking up would automatically connect these to L1/L2/L3 respectively, unless given instructions to the contrary.

However, for hooking up via a flexible cord, we now use brown for all three phases.

For 380V export versions to Continental Europe, they also normally use brown or black for all phases. They also sometimes identify their phases as R, S, T.

You mentioned that your unit is Wye-connected, but didn't say what you use for neutral. You might have a tough time color coding that to match all existing standards for all countries you export to.

It's probably easiest to just make sure that all terminals are clearly labeled.

Joined: Mar 2001
Posts: 2,056
A thought or two...

You say that this unit runs on 3 phase wye, but you list voltages that are(at least in the US) not 3 phase wye.
I believe 380 & 415 are european system voltages. But, 277 is a single phase voltage and 240 is either a single phase voltage or a delta connected, 3 phase voltage.
There is some discussion about not using orange for the 480 volt coding due to the common practice of using orange to identify the "high leg" of a 3 phase, 4-wire delta system.

Joined: Feb 2002
Posts: 183
n1ist Offline OP
Of course I meant delta. And the 277 option turns out to be a low-power (4.7 KVA) single phase option, as is one of the 240V versions. What we will do is have 2 versions of the wiring between the breaker and the barrier strip, one black/red/blue for <= 250V 3ph and one brown/orange/yellow for > 250V. Single phase ones will be black/red. The L1 L2 L3 lables work most of the times, but there are some people out there who insist that the colors must match too. This should handle most of the cases. Worst comes to worst, they will just have to swap two lines to get it to turn on (there's a phase rotation sensor even though nothing else other than the sensor is phase sensitive :-)

While I have been at it, I have also been chasing down all of the white wires that aren't neutrals (blk/red/white/green cables for 3ph without reidentifying the white) and have even ran into a green/yellow wire that wasn't a ground (it used to be green, which was OK since it was a low voltage control line in a bundle of other colors, but someone blindly changed all the greens to green/yellow when they did the CE certification - argh!)

Joined: Oct 2000
Posts: 2,723
Likes: 1
Broom Pusher and

I admire your ideas!

This is a really tough area as color codes can be so different per user area [Continentally Speaking [Linked Image]], and as far as being within the USA, the NEC does not specify the normal "Trade Common" color codes, so that could bring up arguments from certain "Hard-Heads" [Linked Image]

If you do choose for Color codes, being "Trade Common" for the area of use would be a great idea!

For here in the "50 States", I could suggest the following:


[*] 120/240 VAC 1 Phase 3 Wire: L1=Black, L2=Red, N=White, EGC=Green, IGC=Green w/Yellow stripes,

[*] 120/240 VAC 3 Phase 4 Wire (Delta): L1=Black, L2=Orange, L3=Blue, N=White, EGC=Green, IGC=Green w/yellow stripes,

[*] 120/208 3 Phase 4 Wire (Wye): L1=Black, L2=Red, L3=Blue, Common=White, EGC=Green, IGC=Green w/yellow stripes,

[*] 277/480 3 Phase 4 Wire (Wye): L1=Brown, L2=Orange (or Purple), L3=Yellow, Common=Gray, EGC=Green, IGC=Green w/yellow stripes,

[*] 120 VAC 1 Phase 2 Wire: L1=Black, N=White, EGC=Green, IGC=Green w/yellow stripe,

[*] 208 or 240 VAC 1 Phase 2 Wire: L1=Black, L2=Red, EGC=Green, IGC=Green w/yellow stripes,

[*] 277 VAC 1 phase 2 Wire: L1=Brown [or yellow], Common (N)=Gray, EGC=Green, IGC=Green w/yellow stripes,

[*] 208, 240, 480 or 600 VAC 3 Phase 3 Wire: L1=Black, L2=Red, L3=Blue, EGC=Green, IGC=Green w/yellow stripes.
[typical users would ID the 480 VAC Wye system with "B-O-Y", so that's another consideration].


P.S. "EGC" is the Equipment Grounding Conductor and "IGC" is an Isolated Grounding Conductor.

If the cord has a White conductor which will be used for an Ungrounded Conductor, best if it's color was changed to something else [like blue or red], so it doesn't confused the installer.

Need some input from the European sector
[Paging Pauluk! Please pick up the White Courtesy Phone! [Linked Image]]

Good luck!

Scott S.E.T.

Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
Joined: Aug 2001
Posts: 7,520
Picks up phone.... [Linked Image]

If we're talking about generally accepted European colors, then for a 220V 1-ph L=brown (or black), N=blue. For 220/380V 3-ph, all phases brown (or black) and identified 1-2-3 or R-S-T. Neutral can also be identified as 0 (zero).

For U.K. 240V 1-ph and 240/415V 3-ph market, flexible cords would now be the same colors as above, with phases identified 1-2-3 or A-B-C. There's a conflict though, because we still use our old color for fixed cables: L1=red, L2=yellow, L3=blue, N=black. Take your pick on which to use!

In all cases, EGC would now have to be green/yellow to meet current standards.

The European blue for neutral is why I mentioned that you might have a hard time coming up with a single scheme to suit all markets.

Also, most people on this side of the Atlantic would not associate white with neutral. In fact, although not defined for any purpose these days, white was actually the British phase-B color until 1964, and may still be in use as such in some buildings.

Very difficult trying to reconcile all these different schemes.

[This message has been edited by pauluk (edited 05-25-2002).]

Joined: Apr 2002
Posts: 2,527
Scott35-- A big-time research lab in NorCal uses your items 1-4. in your list, EXCEPT that in 4. it's 277/480 3 Phase 4 Wire (Wye): L1=Brown, L2=Yellow, L3=...Purple, to best correspond to their original [~1958] 480V standard of black-yellow-green. (!) Then, it was all 3-wire delta. Equipment grounds were always bare, and the old timers would get excited when you used green-insulated wire for the same.

A difference there is single-phase loads [ø-ø and ø-n] used the respective phase color(s) they were served from.

Joined: Aug 2001
Posts: 7,520
Green for a phase??!! Was this just a peculiarity of the lab in question, or was it ever accepted elsewhere as well?

It also begs the question, when did the BOY system become common practice?

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