On Tue, 1 Sep 2015 11:20:14 +0100, newshound wrote:

As a matter of interest, what's the typical voltage of the three
wires
connected to porcelain/glass insulators, mounted on wooden poles,
that
feed the transformers (often pole-mounted) that step down to 240V
for
overhead wiring to houses?

I thought they were 11 kV or 33 kV but someone who knows will be along
in a minute!

11 kV is the normal distribution voltage to end users from a Primary
substation (pole transformers are classed as "sub-stations").

The Primary substation will probably be fed at 33 kV or higher
depending on how big it is. It will almost certainly have at least
two feeds, main and reserve. The reserve to the Primary substation
here is 11 kV, the main 33 kV.

What haapens on the 240 V side varies greatly, it can be 4 wire (3
phases, Neutral and Earth) any single phase supplied property taking
a phase N and E. Down to two wire, phase and combined Neutral/Earth,
this is what our supply is. The Neutral is bonded to physical ground
at the pole.

--
Cheers
Dave.