On 12/10/2020 11:55, Andrew wrote:
On 12/10/2020 11:32, Tricky Dicky wrote:
On Monday, 12 October 2020 at 11:26:10 UTC+1, Jack Harry Teesdale wrote:
On 12/10/2020 10:13, JohnP wrote:
Looking down a hole - as I do - there are some modifications being
done to
cables at a nearby substation. Some of the old cables are being
extended
with "twisted three" cables rather than the usual three phases in a
circular outer.

Any ideas why?

It's cheaper.
I saw that when they dug a trench through a local garden centre car
park to get to a substation and was intrigued. No idea if it is
plaited already on the drum as I never saw that but it looked too neat
and regular to have been done on site.

Richard


I thought that was the aluminium stuff that is regularly used to replace
the 3-phase copper up on poles ?.

Is each conductor separately protected with a steel outer braid, SWA
fashion, or they just using physical depth plus a concrete cap to
protect it ?.

Many UK utility company distribution cables are aluminium these days.

The cables are usually XLPE (cross linked polymer) insulated with a
layer of aluminium stranded armour for protection.

Some cable types incorporate a copper tape screen layer to provide a
earth fault current return path.