Underground cables

AIUI you cannot mix mains and SELV in the same duct. There are trucking systems with a separator that solve this problem, maybe there are ducts also?

It is acceptable for an armoured cable to coexist with SELV cables.

use armoured mains cable bare in the soil for the mains and the ducting for any other stuff

Is it permitted for customers to have a combined PEN after the service intake?

Owain

That would be TN-C wouldn't it?

I am 99% certain that is explicitly prohibited in domestic installations (and probably others).

I've often wondered about this earthling of Neutral though. Can this really work without doing any harm? Brian

I take it that's 110m rather than just over 4 inches?

That seems a little strange...

Generally its best to keep signal level cables and mains stuff segregated. Normally if laying in a new duct, you would run the mains submain *outside* of the duct using SWA, leaving the duct free for other stuff.

A TT installation perhaps, such as a rural house with overhead power feed. Would be unusual in a built-up area.

You don't normally put one of them in a duct or conduit to separate them when you run power & networking in interior floors, though, do you?

yes.

In pro installations you do

You often have segregated trunking to keep mains and CAT5 etc separate...

TT would not have the earth rod connected to the neutral - it would be connected to the local earth of the installation, and there would be no connection to the supplier's earth (since there probably won't be one!)

I guess that's probably common in commercial work, but I've never seen phone wiring deliberately separated that much in houses. My network cables are separated from power (between different pairs of joists, for examples) --- they just ended up that way, although if I were running them along the same joist I would make some effort to clip them with a good gap.

You cannot use T&E in an underground duct - the duct will full of water.

Inevitably, my SELV cables sometimes run near mains cables. I put them all in dedicated flexible trunking.

If that's a legal cannot - Well, that's the law.

But practically? Vinyl in the dark lasts forever, and the only way water could get in would be the ends.

Andy

Will this drop the volts even more ?.

No-one seems to have mentioned the cable size required (fat).

And what is being powered in the sheds ?. Lighting or beefier stuff.

No water can get anywhere. It will get in at any joint and there's also condensation if the ends are even slightly open. Any air pressure difference between the ends will draw humid air into the duct where it will condense. The low point of any duct should be drainable and the whole length should run down to that low point.

Bill