On 18/03/2017 15:57, Andrew Mawson wrote:
"NY" wrote in message
...

SNIP

How much of the route from the power station to the consumer is
redundant multi-circuit? At one point, typically, does it change over
to a given house only being fed by one set of wires, and if that line
develops a fault there is no backup circuit?

Is there a backup route as far as the final substation that transforms
to 11 kV or 400V, or is it higher up the chain?

I presume for maximum redundancy they try to use feeds from different
places rather than two sets of wires carried on the same pylons, in
case an accident takes out *all* the wires (both circuits).

I'm intrigued at the way house gets its electricity supply. There is
overhead mains on wooden poles (originally four separate wires, now a
single fat cable with four wires) and our house is the middle house of
two adjacent blocks of three houses. There is a single feed from the
wooden poles to the end of one block, and then four wires running
along the back of one block, overhead across the gap to the next block
and along there, with each house taking its feed from neutral and one
of the three phases - I think no two adjacent houses are on the same
phase. I suppose this is less unsightly than every one of the six
houses having its own single-phase feed from the street poles.




They always used to rotate phases down a street, so (say) phase 1 -
house 1, phase 2 - house 2, phase 3 - house 3, then phase 1 - street
lighting, phase 2 - house 4 and so on down the road to balance the load
between phases.


Yep, and it's not uncommon to see that in multiples of houses. So you
may have 4 houses next to each other on phase one, the next 4 on phase 2
etc.

A far more common variant (on properties built in the late 1960's and
early 1970's) is house 1 and 2 on phase 1, house 3 and 4 on phase 2 and
house 5 and 6 on phase 3.




--
Adam