Hole for the electric supply wires ?

[George (dicegeorge)]

How should I prepare a hole for the electric supply wires to come into my house please?

Now they come in through a hole at the top of the door frame.

I would like them to come through the brickwork higher up.

When I have the hole ready I will phone up the electricity company and get them to come and poke their wires through the hole and install a new meter and an Isolator switch.

I could cement a foot of metal box section up there.

Or cement wood so that they could drill through it.

Or caulk a foot of drainpipe in there, or some other kind of plastic.

Or is there a box with grommets which I could buy?

And how can I seal the hole against heatloss after they've gone?

Thanks, george.

[Tim S]

George (dicegeorge) coughed up some electrons that declared:

Will this involve a cavity wall?

Long and short is: cavity walls sometimes contain polystyrene insulation and polystyrene eats PVC cables (specifically it leeched the plasticiser out).

So in that case, you will need to sleeve the hole with uPVC (ie conduit, bit of 40mm waste pipe etc). Don't use 25mm conduit - too small to get 2 x

25mm2 tails though plus earth. I think 32mm would do, definately 38mm but those are "industrial" grades to harder to get (CEF list them though, need to buy 3m length).

If you've got a solid brick wall, sleeving isn't essential, but it would do no harm.

Have you checked with them first? EDF for instance may want you to fax an EIC to them before they are willing to connect anything.

As above

You don't need anything that fancy. Typically the meter tails would come through near or even into the back of your CU (consumer unit). You might even build a little cupboard around it, but tails these days are double insulated so having a bit on show is harmless.

You'd need grommets for taking them into a metal CU, but not plastic.

Cupboard round the CU would do. Or pack the hole with a bit of something that's harmless to PVC.

Any of that help?

Cheers

Tim

[George (dicegeorge)]

thanks, so I could cement in 3 plastic pipes (one for each wire) sloping downwards towards the outdoors for any moisture?

[The Wanderer]

Coming through the door frame suggests quite an old installation.

Looking at the existing cables, are they pvc sheathed, or do they have a sort of woven 'canvas-looking' outer layer? If it's the woven fabric outer layer they're quite old, and are known as PBJ cables (poly butyl jute).

If they're pvc, the distribution company will probably make a charge for anything you ask them to do. If they're PBJ, they'll be reaching the end of their serviceable life and you should be able to get them to replace the whole lot for free. The inner insulation (butyl rubber) tends to go brittle and crack, especially on sharp bends.

[Dave Liquorice]

I'd be happier with the wires kept as close as possible together. No real facts just a gut feeling. With the wires separated there is going to be a stronger stray magnetic field which could induce eddy currents and heating in nearby metalwork.

Slope down to out is a good idea. I'd just bung in a bit of 50mm uPVC waste pipe(*). You don't want something with a small opening as 25mm tails have quite a large minimum bending radius. If the cable can't bend until it clears the pipe it's going to have to project from the wall and look really messy with the drip loop etc. With a larger opening some or all of the bend can be hidden inside.

Sealing? Outside a bit of weak mortar inside a or a few loosely filled with fine dry sand sand bag(s).

(*)Note other comments about PVC and polystrene though.

[George (dicegeorge)]

a pic i just took of the wires coming through the door.

I think the cables are sheathed.

Could i say its not up to modern standards going through the door frame?

I dont mind paying if they will fit an isolator but dont tell them that

My plan is to cement 2 or 3 plastic pipes through the wall either where the earth wires are coming through or a little bit higher up and ask them to reroute their cables through there...

Should their two cables share one plastic conduit, or would 2 be better?

[Tim S]

George (dicegeorge) coughed up some electrons that declared:

Seems reasonable. The only time you mustn't use separate pipes (or holes) for the L and the N is if the pipes were ferrous metal and/or the holes went through a metal box (eddy currents are a problem and things get warm).

Sounds like your plan is fine (including the sloping down which is a very fine idea that I forgot to mention *cough*).

Cheers

Tim

[Tim S]

George (dicegeorge) coughed up some electrons that declared:

It's hard to tell. They could be:

meter tails)

Best you have a look at the picture above and compare - too hard to see in the photo.

If the cables look stable and new-ish, you might just be able to read "6181Y" on the sheath. If they're older, they may not be marked.

They're probably not ancient as 40 years ago, they may have been single insulated red and black.

It's not desireable - what if you needed to fix the door frame?

Assuming they do. EDT in the Seeboard area won't (I asked). In teh London LEB area (still EDF) they don't care, but the meter operator (someone else) may do. Confused yet? Jolly good - that's privatisation.

Which company are you under (network operator, not necessarily the same as the people you pay)?

It's fine (with the caveat about not using ferrous metal in my other post). One tube might be neater, but two 25mm holes should do it quite nicely and them you can pick up a bit of 25mm conduit at B&Q. You could manage with 3

20mm holes (might be a squeeze to get 16mm2 earth and 25mm2 tail though one 20mm hole) if drilling 25mm is a problem.

Cheers

Tim

[Owain]

If you phone the electricity company before you get the hole ready they may send you one of their specially-approved through-the-wall-tubes which you can use, included in the cost of the job.

Owain