Burying cables in wall - protection against nails etc.

[romic]

I need to bring cables from upstairs to downstairs to the consumer unit. Total around 10 T&E in various thicknesses.

The only relatively fool proof part of a wall is where the existing cables come down and I don't want to remove these until the wiring is complete.

I therefore need to run them down a separate part of the wall - I have a 2 foot space between the kitchen door and the living room door that would be ideal.. Sods law says that somebody will no doubt bang a nail in the wall in the future, co I need to give the cables protection.

As I see it, I have the following options:

a) Feed the cables through metal conduits, then plaster over these. The plaster will have to be a bit deeper than the existing half inch. The cable from the shower would have to be placed out of conduit at the edge of the wall.

b) Bury the cables in the plaster as normal, then cover with a sheet of suitable metal for protection

and that's it! any other suggestions?

Would there be any problems with running a T&E cable (1.00mm and 2.5mm) in a 10 foot vertical drop without any support?

Thanks

Roger

[Rick Dipper]

If its a cavity it might be an idea to run them in the middle.

If its possible that in futur you may want more, it may be work putting up a thin "fake wall" made of plasterboard .. This is especially usefull if you have pipes to run as well ....

Just some ideas

Rick

[Coherers]

A simple method is to use metal capping rather than the standard PVC stuff - this will provide **some** degree of protection. But you must earth the capping if it is to be any use, as it provides no real mechanical protection. A nail/screw drill hitting a cable will be earthed by having passed through, and still being in contact with, the metal layer (with luck!) thus triggering the protective devices, and hopefully acting as a better route to earth than the eejit with the hammer/driver/drill ( delete as applicable).

You should earth-bond your sheets / conduits anyway

Maximum spacing for support for vertical PVC cables is between 0.4 and 0.55m , depending on cable thickness....

[Martin Angove]

I like the false-wall idea, but if pipes are included don't forget to space them as far away from the cables as possible if they are hot, or else you're going to have to do some derating calculations on the cables, and possibly even uprate the type of cable if the pipes are hotter than the 70-odd degrees PVC can withstand.

A false wall might take a picture-nail without affecting the wires, but anything more substantial is going to be a problem even then.

Hwyl!

M.

[Martin Angove]

Metal conduit or capping will need to be earthed which can be a bit awkward to do.

In conduit or capping it shouldn't be a problem. If you are just going to bury in plaster then you'll need to put in a few cable clips, if only to keep the cables close enough to the wall to be able to plaster over them!

Back to the original problem though, if this is a relatively short-term project and re-using the old route is "best" (as you implied) then is there any way you can feed the old circuits temporarily by another route, thus allowing you to bypass the section in question? I'm thinking of a few carefully worked-out "extension leads", and probably not for the shower!

Hwyl!

M.

[Jerry Built]

I've just re-wired the upstairs lighting in a 1950s. house where the cable for up/downstairs light/ring were all run down through the cavity and back in at the CU.... I don't know how "acceptable" this is, but there was no damage to the wiring... I just replaced it as it was with new.

J.B.

[Fash]

Not acceptable, but unlikely to cause problems. Wiring should now not be run in cavities due to potential issues with condensation. Is there no way you can run the cables down within 150mm of a corner of the room, in which case you can do what you like, no need to worry about protecting the cable, the point being that no one is expected to bang a nail in to the corner of a room since the picture would look a bit silly hanging there. Similarly you can run in the top 150mm from the ceiling wherever you like, BUT this is not true at the bottom of the wall.

Fash

[romic]

Thanks for the comments.

It is not a cavity wall, which makes it more difficult. The existing cables are buried in plaster.

It would seem like the only real option I have is to run the cables down the existing location. I will need to look into this further and do some more checking.

In my original post (as above) I mentioned running cables in a 10 foot drop without any vertical support. What I forgot to make clear was, in this instance, the cables would be in individual conduits and not just left dangling. Would this make any difference?

Roger

[steve]

Why not stick ( no nails , hot melt, impact adhesive whatever) DON'T NAIL OR SCREW IT!!!!! pvc trunking onto the wall over the existing run. then you can remove the lid and add the cables as you add new circuits .Then when all cables run , remove the temp plastic trunking chop out the plaster and remove old cables the put new cables in wall with plastic or galv steel top hat type protection , doubt you will get any wide enough to cover all the cables in one go or run in the conduits remember you can get oval type conduit , round would probably involve chipping away some of the brick/block to get it flush under the plaster then plaster/ make good

[romic]

That might have to be one way of doing it. As I'm doing it a bit at a time, I would much rather have dove it permanently at a new location, disconnecting the old cable at the CU then connecting the new one as I go along. I could then clear out the old stuff at my leisure.

Roger

[romic]

The most simplest new location (from upstairs access) is down an 18 inch wide wall between two doors. However, because of the narrowness of this and the amount of cables, I will need to run cables for most of the six inches at either side of it, leaving a six inch gap in the middle. Because the wall is narrow, I'm concerned that at some time in the future there is more chance of a nail/screw going into the wall within the six inch margin. If I could run the cable in metal conduit for the drop, I wouldn't be bothered. However, I don't want to run the risk of future damage - possibly even done by myself without thinking!

Roger