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On Wednesday, November 25, 2015 at 3:12:24 PM UTC-5, Ralph Mowery wrote:

I hope that damn 2 phase 220 house wire does not start up again. There is
a
true 2 phase and then then there is the split phase 240 that is common in
most of the houses in the US that some try to claim is 2 phase.

OK - I live near Philadelphia - which, together with Baltimore, MD shares
one of the last areas in the US where one may still get actual 2-phase
power. 2-phase, 4-wire power was developed primarily for heavy motor use
in that era when the battle of AC vs. DC was not yet settled and 3-phase
power was barely a gleam in Tesla's Eye. (SIDE NOTE: The last DC building
in NYC fed from the Pearl Street Station (for ~125 years) went down in
2007.) For whatever reason, both Philadelphia and Baltimore accumulated an
inventory of heavy freight elevators that use 2-phase motors to this day,
such that the local utilities continue to supply the power to a very few
customers in specific locations within each city. I had the privilege of
working on several such elevators and heavy water pumps in my youth while
working my way through school as an electrician.

NOTE ALSO: some few households at the time also got 2-phase. And both PA
and Reading railroad workers living along the rights-of-way got 25-Hz
current - used for railroad traction motors, also to this day.

Standard household power in the US is 1/3 of a Delta-connected 3-phase
system, being hot-to-Hot at a nominal 240V and hot-to ground at 120V.
Single-phase as only 1/3 of the total capacity is realized. All this is
done in the single-phase transformer at the sub-station, not the
distribution transformer at the pole (vault) in the neighborhood.

Peter Wieck
Melrose Park, PA



I know that in some parts of the country you may run into many different
kinds of power in the houses, just not too common.

Only reason I mentioned the 2 phase stuff was because of the origional
question. I doubt that a house hold dryer would be 2 phase, but who knows ?

I bet it would be difficult for the average home owner to have a house wired
with anything but the standard 120/240 system of most of the country and get
anything to work.

Living in the south I doubt much if any of that 'odd ball' power was used.
About the only "odd" voltage I see is some 208 volts phase to phase with 120
to the neutral instead of the 240 p to p.