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if the panel is labeled as 3phase 208/120v,wouldn't you be required to feed it as such,

I don't think so.

Any more than you have to feed a 225 amp panel with 225 amps.

Or any more than you have to supply a Square D I line at 600 volts just because it is able to handle that voltage.

IMO where you would run into trouble is when you try to supply a straight three phase panel with Wye.

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But then again, I don't share neutrals either.

Actually you share neutrals with every circuit on the supply side of the source.

Electrons do not know or care which side of a panel they are, they act the same either way.

You can deny it to be true if you want but I challenge you to show how it differers electrically from one side of a panel to the another.

BTW I had to bring two branch circuits to each of two 9 panel LED screens at a concert venue.

You'll never guess what the vendor specified.

An L21-30R

[Linked Image from marchansen.com]

Thats 3 hots with one neutral for those following along at home. [Linked Image]

It worked flawlessly and aided in combating voltage drop on the 400' runs of 6 AWG. [Linked Image]



[This message has been edited by iwire (edited 11-11-2006).]

Bob Badger
Construction & Maintenance Electrician
Massachusetts