The power company uses only a single line to a single transformer.
The two phase is High Voltage. (Was a Saw Mill here 20 years ago).

The transformer is a 130-0-130 but who is counting.

I have 3 phase 380 in the shop that I generated off the shop panel
in a rotary (220v 3-ph) and six transformers. But that is in the shop.

House wants normal power for electric everything. No gas. Damn.
I'd have to dig several thousands of feet or drag a hose in a trench
and paying for 1200 feet of hose and meter. Gas company declined.


Martin

On 3/15/2017 8:24 PM, DoN. Nichols wrote:
On 2017-03-15, Martin Eastburn wrote:
How much would a 120v or 120-0-120 aka 240v circuit cost to put in ?

This property has 3 power meters. Shop, House, Library.
House and Library share the same 2-phase Power pole. (YES really
2-phase). The street has a full set of 3 phase. Two legs and power
come onto my property.

What you have may be the best you can get. You've got 207V
between the two phases. And what you have can be treated as three phase
open delta -- so you can run three phase motors on machine tools.

Is there a particular reason you want 240 VAC instead? Perhaps
something which won't run well on 208V.

If you trade off the current 208V feed for the 240 VAC feed,
they would disconnect you from one of the transformers, and connect you
to an extra winding on the other transformer (assuming that it is
present -- and that there is not enough load on it to preclude it being
used as a 240V single phase feed). If there is, you may have to have a
new transformer installed. And no, I don't know what the cost would be.

An alternative is to get a boost transformer for just the loads
which need 240 VAC and connect it between the two phases which currently
give you 208 VAC. And that transformer you would own, unlike the
transformer on the pole.

Good Luck,
DoN.