New cables into substation

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

as he said. its cheaper, and you only need an outer when you need additional protection on the outside, or to carry an earth potential..

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 ?.

Saw electricity supply to a new housing estate being laid the other week. Three lots of "twisted three" in a trench - with plenty of very hefty sealed junctions. All outer layers were red. Didn't see the actual covering process but suspect a bit of gravel then some concrete and asphalt.

There are some buried cables near here laid as two sets of three red cables side by side. There is a buried oil pressurisation tank. Every few years holes get dug as they look for oil leaks. I was told that these cables run at 33kV but could be operated at 66kV.

John

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.

Aluminium armour doesn't seem to provide much protection, surely, compared to steel armour ?

Aluminium is cheaper and doesn't rust! Even the steel wire armour is easily penetrated by JCB type diggers, so not really that different.

Pure convenience and easier to get them routed around existing infrastructure? Brian

I've noticed a lot of round black cable replaced with the red twisted conductor cables in recent years

BS7870 Part 4 section 4.10 "Triplex" apparently