How is it possible to go from a 3-phase circuit with 3 hots 120 degrees off from each other and a neutral, to a 2 phase circuit with just 2 hots and a neutral and have those 2 hots be now 180 degrees off from each other??

For single phase all you need is any two legs of the 3 phase system. For a neutral the system will need to have a grounded leg, which should be the center point of a WYE system.

What type of system do you have?

How can you disagree with something your not sure about?

Did you notice I asked a question, therefore I am not done explaining?

Using two legs of a three phase system is not called "2 phase", it is single phase.

And each conductor is still 120 degrees apart.

Single phase is not 180 deg, one single phase circuit is 360 deg.

So, are you going to answer my question so we can have a dialog to get answers to your questions,or will you continue to complain?

I apologize if I sounded argumentative before, it was not my intention.
I did not mean to rate answer before, I was not sure where to click to reply.
Anyway, you were asking what kind of system I have, my question was not related to my actual system, just curiosity in general. I understand that usually a 220v circuit with obviuosly 2 hot wires and a neutral is called single phase. This also puzzles me because what would you then call a 110v circuit? Single phase too?
Back to the 220v circuit, I meant that the 2 hot leads are 180 degrees off from each other, and if so since the 3 hot leads in a 3-phase circuit are 120 degrees off from each other I just can not understand how to use a 3-phase circuit to make a "single-phase"
220v circuit. Thanks, JCV

Ok, no problem.

Perhaps I can overload you with info. Review this site:The 3 Phase Power Resource Site - Three Phase Power Solutions (http://www.3phasepower.org/).

3 phase can be a bit confusing, so pick through the info at the website, see what you can understand, what do you already know, and we can go from there.

Yep, 3-phase power is a bit difficult to understand.

Generally you will find 125, 208 and 277 and 480 in a plant or 440/220/120 in a plant that has 3 phase power depending if the transformation is Wye or Delta. 277 generally goes for lighting. Between any of L1, L2 AND L3 there will be 208 or 240 volts. 208 is 120 * sqrt(3). 277 = 480/sqrt(3)

Some buildings like ours have multiple power panels. We even had euopean voltages generated. Some parts of Japan use 100 V, where others use 120.

This is why the universal power supplies must be able to operate from about 95 V to 285 vac to make it universal.

In a single phase residential system you will find 120/240. Basically the center tap (120-0-120) of the transformer is grounded.

You can convert 3-phase power to 2 phase power using a transformer in a Scott-T configuration. See details of this on Wikipedia at:

Scott-T transformer - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Scott_connection)

Not too many companies sell Scott-T transformers, but there are some you will find in a Google search.