On Tue, 03 Feb 2009 17:43:46 -0800, David Nebenzahl
wrote:

On 2/3/2009 5:25 PM Mark Lloyd spake thus:

On Tue, 03 Feb 2009 16:27:35 -0600, "Pete C."
wrote:

E Z Peaces wrote:

David Nebenzahl wrote:

On 2/2/2009 6:40 PM Pete C. spake thus:

David Nebenzahl wrote:

The question from the person in Peru about wiring for 230 volts raises a
question: in places that use 230/240 volts for household current (i.e.,
most of the world), how is that power brought into the house?

Here, we have 2 "legs" of 120 volts each (two hots and a neutral)
of opposite phases, so that you can either tap 120 from either leg
or 240 between them.

They aren't "opposite phases", they are opposite polarity as they are
the center tapped (center is neutral) output of a single phase
distribution transformer.

Yes, same phase, opposite polarity. My bad.

I think you were right. The transformer on the power pole produces two
phases from one phase. Because the difference is pi radians, the
polarities will be opposite when polarities exist.

No, it produces a one phase 240V output. The center tap on that output
confuses people, but the output is indeed single phase.

It's either 120V (2 phases) or 240V (1 phase). The difference is in
the point of reference. That's normally the ground.

Right.

After this point, any more discussion is just arguing semantics.

Mostly, although the center tap is still the most groundlike point.
That's normally the point of reference for measuring voltage.
--
Mark Lloyd
http://notstupid.laughingsquid.com

"The government of the United States is not, in
any sense, founded on the Christian religion."