Three phase lines in USA

    • M
  • posted

Hello

I'm spanish, my english is not veri good.

Exist three-phase lines in USA of 120/208 V or 127/220 V for comon uses (single-phase for houses and three-phase for power)??

Or alwais use single-phase lines of 3 wires 120/240 V??

A house conected to 3 wires, high votage for power - low voltage for lights and general use, make possible connect the 3 wires of house using 2 phase + neutral of three-phase line??

The plug Nema 14-15, make possible connect the 3 wires of house using 2 phase + neutral of three-phase line??

Thanks!!

PD. In Spain, cohabit three-phase lines 127/220 V and 230/400 V, 50 Hz, in star system

Reply to
MaKiNeRo d(Ò ó)b
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Three phase power has not been supplied to homes in quite some time.

Yes.

No. The voltage between two of the wires is 240. The voltage between either of these "hot" wires and the other wire is 120.

No. The old three phase system had four wires. That is 3 hot wires and one common ground. We call that Y connected.

Similar to our 3 phase system, but we use 60HZ. Jim

Reply to
Jim

It has got to be better than my Spanish.

Yes and no.

120/208Y, 3 phase, 4 wire, 60 Hz is very common for light commercial installations such as shopping centers.

It is not used for residential applications,

120/240, 1 phase, 3 wire, 60 Hz is used for most residential installations.

This wiring configuration is commonly known as the 3 wire Edison configuration.

It consists of a 240V transformer secondary winding with a center tap.

Leg to leg(L1 -L2) = 240Volts

Leg to center tap (L1-N) = 120Volts.

Both are 60 Hz, single phase, not 3 phase.

If you need 3 phase power in the US, it is usually only provided in commercial/industrial areas.

HTH

Lew

Reply to
Lew Hodgett

*IF* three-phase is in use, it will be 120/208 V, not 127/220V.

Answer: "It depends". 120/240V single-phase is, by far, the most common. for pure residential use. However, there are towns where some areas have three-phase distribution, and a given house will have "2-of-3 phases" from the pole, giving 120/208 V.

Note: in such locales, the customer does *NOT* have any choice as to whether his property is served by 120/240 single-phase, or 120/208 '2-of-3 phases'; the customer gets "whatever the neighborhood is wired for".

Bigger apartment (or condo) buildings, are more likely to have three-phase into the building, with "2-of-3 phases" going to any particular unit.

Reply to
Robert Bonomi

Unless it's 220/417 V, but you're only going to see that in commercial/industrial buildings.

Reply to
Roy Smith

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