Three phase lines in USA

In article <iK5%[email protected]>,
MaKiNeRo d\(Ò_ó\)b <[email protected]> wrote:
>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)??

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

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

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.

"MaKiNeRo d(Ò_ó)b" wrote:

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

It has got to be better than my Spanish.

>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)??

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

In article <[email protected]>,
[email protected] (Robert Bonomi) wrote:

> In article <iK5%[email protected]>,
> MaKiNeRo d\(Ò_ó\)b <[email protected]> wrote:
> >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)??
>
> *IF* three-phase is in use, it will be 120/208 V, not 127/220V.

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

"MaKiNeRo d(Ò_ó)b" <[email protected]> wrote in message
news:iK5%[email protected]...
> 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)??
Three phase power has not been supplied to homes in quite some time.
>
> Or alwais use single-phase lines of 3 wires 120/240 V??
Yes.
>
> 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??
No. The voltage between two of the wires is 240. The voltage between
either of these "hot" wires and the other wire is 120.
>
> The plug Nema 14-15, make possible connect the 3 wires of house using 2
> phase + neutral of three-phase line??
No. The old three phase system had four wires. That is 3 hot wires and one
common ground. We call that Y connected.
>
> Thanks!!
>
> PD. In Spain, cohabit three-phase lines 127/220 V and 230/400 V, 50 Hz, in
> star system
Similar to our 3 phase system, but we use 60HZ.
Jim
>
>
>