when running wiring for a socket in a chase in the wall can I just plaster it in if it runs in a straight line horizontally or vertically, or do I need to put it in oval conduit in the chase before plastering over to protect it?
It is always preferable to protect cables as much as possible, especially if they are hidden in walls or behind timber, in case someone decides they want to hang something on the wall where the cable is. The current requirements say that you can place cables in straight lines from point to point, except within 150 mm to 200 mm around the edges of the walls and no diagonals are allowed. But, for real safety, it is better if you can clad with a metal barrier to stop anyone drilling or banging nails through the cables.
Something like the galvanised cladding on this page is ideal.
Neither! Best to cover it with galvanised hop-hat section trunking, and then plaster over that.
This will protect it from accidental drillings or nailings (because you will hit the metal trunking *before* the cable) and will also allow the cable to move slightly without cracking the plaster.
Roger
requirements
Very few people use the metal capping now. It is OK to just clip the cables to the wall and plaster directly over them but it is better to cover them with plastic capping.
Adam
Hmm, 3 counsels of perfection. There's no blanket requirement in the Regs to use capping or conduit, and absolutely dominant practice in new builds is to do without. What the regs require is that cables should be protected from reasonably foreseeable mechanical damage; and in a normal house wall that means small nails/picture pins. From this, the On-Site Guide says you can route such cable (a) *anywhere you like*, yes, including diagonally and near the floor, IF it's more than 50mm deep from the surface of the wall; or (b) within 150mm of the top of the wall or within 150mm of a corner; or (c) horizonally or vertically to a visible electrical wiring Thing ("accessory or consumer unit"), e.g. socket, switch, cable exit, etc.; or (d) enclosed in earthed metal conduit/trunking/ducting.
The rationale seems to be: for (a), not many nutters will use big screws or nails ("big" = bigger than 2 inch) without a bit of caution and maybe a 10quid live wire "detector"); for (b), not many nutters will put up pictures or fit IKEA's cupboard-anti-topple things in those parts of the wall; for (c), not many nutters will fail to notice electrical fittings and be cautious about a cable running horizontally/vertically to them; and (d), that not many nutters will carry on drilling once they've hit metal rather than masonry. (Personally, I think I know a few nutters who might try any or all of (a) to (d), but the Regs and OSG try to anticipate only ordinary nutters, not the sort I seem to collect ;-)
So if you want to use galvanised capping, you can; but it's neither required, nor (unless you earth it) compliant by itself with the (d) alternative above (since masonry-nailing top-hat capping over the cable gives you something which isn't earthed and doesn't enclose). In summary, there's a rather narrow band of circumstances in which such capping is sensible: where there's an increased chance of damage to the cable, but not enough of a risk to bother with real, earthed conduit or rerouting or deeper burial.
HTH, Stefek
Easier to pull a replacement cable if it's under some cappping. When you buy the plastic top hat stuff (dirt cheap), remember to get some capping nails. They're hardened so will bang in straight and easily.
You must do totally different new builds to me. Capping is the norm on a nice new wall.
So if you want to use galvanised capping, you can; but it's neither required,
That is why no one uses it.
Adam
Maybe you should teel the contractors who did the house up the road last month. Metal capping everywhere, very nice job !
Dave
Interesting to hear that. (I don't do any electrical work professionally - my impression of new build practice is based only seeing the insides of houses I or close family members have lived in). Clearly there's *some* usage of capping, or the likes of TLC/CEF wouldn't sell it ;-)
Thanks, Stefek
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.