"Robert11" <rgsxrose@comcast.net> writes:

Figured that this would be a good site to post my question.

You may also want to check out alt.engineering.electrical

From what I see, there are "usually" 3 lines on the upper part of the

which I'm reasonably sure are the power lines.

Yes.

The upper, middle one, I'm guessing is a "high voltage" line.
Correct?

This is three phase power. I assume you know how AC is, the voltage
varies as a sine wave going positive to negative and back to positive
60 times a second (in the US). All three lines are at the same voltage
but the 3 sine waves are shifted by 120 degrees relative to each other.
So they are not the same and can't be replaced by a single line.
Three phase power is done for a few reasons: Constant power transmissions
when all 3 lines are used (instead of going from 0 to max 120 times a
second for one individual wire) and larger motors (over 2 HP) need it to
run. You can see where businesses have 3 phase supplied to them when
there are 3 transformer "cans" on the pole servicing them. Look closely
and you'll likely see each "can" fed from the 3 lines, one per can.

What voltage do they usually carry (residential area, street poles) ?

It varies by quite a bit, from 4800 volts to 25,000 volts or so. Usually
about 13,800 volts.

If so, where is the ground for it ?

Usually a neutral wire runs along the middle of the pole, it is grounded
at every transformer.

What are the other 2 ?

The three together are 3 phase.

Different phases (115 V each relative to some ground ?) after the high
voltage is reduced via the periodic pole transformers ?

The 120 volts sometimes runs one or two poles from the transformer,
usually 2 lines wrapped around the neutral, and at the middle of the pole.
The neutral is shared with the high voltage's neutral. The hots have black
insulation and the neutral is bare aluminum.

--
-Mike