"DoN. Nichols" wrote in message
...
In article .com,
wrote:
Can you get 120v single phase by picking off one line of 240v 3
phase
as long as you have a neutral to carry the current back to the box?

Not quite. The voltage won't be right for pure three phase. I
think that with Wye connections, you will have something closer to
104V.

Typo? Should be about 140 volts from line to neutral with 240 wye
(calculates to 138.6 or so)

208 wye gives 120 line to neutral...


And many are delta which *has* no neutral. All may be floating.

But a frequent variation has one of the three sides center
tapped (the way the standard residential feed is supplied, 240V
center
tapped with the center tap grounded and neutral connected to that.)

The breaker boxes for this have three buses, but only two of
every three positions can be used for 120V single-phase breakers.
The
third phase is *way* too high.

However -- from *any* reasonable 240V 3 phase, you can tie two
of the three phases to the primary of a 240-120V step-down
transformer,
and power your equipment from that.

Enjoy,
DoN.

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