On 16/04/2021 22:26, Rod Speed wrote:
"Scott" wrote in message
...
On Fri, 16 Apr 2021 20:36:02 +0100, charles
wrote:
In article , NY wrote:

What are the circumstances when overhead mains wiring has an extra
earth
wire, rather than the earthing being done at each house? I've never
seen
it before. Come to think of it, why do some installations have a
neutral
wire and some don't - are there cases where the nett load is
expected to
be unbalanced on the three phases, requiring an extra neutral?

Are you saying that telephone wires in the UK always require separate
poles and can't be carried on electricity poles?

that certainly used to be the safety requirement.Â* Nobody wanted 240v on
their telephone.

I would have thought 240V at the exchange would be an even bigger
problem.

Nope, they have to have some protection against lightning strikes
and that works for 240 volts too. In fact many street power lines
have 11KV lines at the top of the poles too and sometimes someone
drives into a pole and brings it down, with the 11KV lines with it.

Is that 11kV between phases?

--
Max Demian