Plaster come away over conduit

fenwick458

grumbler said:

fenwick458 said:

you can wait for someone to confirm before you believe me if you like.
not sure what the 50mm minimum to protect from the trowel is about?? 

So far I don't see any real confirmation. Just urban myths that all forums are full off.

Re 50mm -

grumbler said:

...

"All electrical cables should be set into the walls at a minimum depth of 50mm if they are not mechanically protected. If it isn't possible to chase the walls to that depth then the cables should be set deep enough so that metal capping can cover them and allow for plaster to cover that.

..."

This information is just from some forum (Answered 14th May 2014), so I am not saying that it's correct.

Yes, this, possibly, is an urban myth too, but at least it makes some sense to me - unlike protecting the cable from a plastering trowel.

I really don't know how it makes sense to you. if your hanging a picture, those little picture nails go right through and you'll never even know about it, it's impossible to tell by feel alone. if it were a 3 mm steel plate then yeah it would offer protection against these nails, but it's not.
on the other hand, a plasterers trowel is razor sharp, and they apply pressure to the wall an move it up and down in line with the cables, and you don't see this pose a risk to the insulation on the cables getting sliced?
capping isn't used anymore anyhow, it has disappeared with the advent of dot n dab, where plasterboards are just stuck on the wall. a lot less chance of the cables getting nicked

grumbler

fenwick458 said:

I really don't know how it makes sense to you.

OK, if you ask.

The nails I rarely use are small and not perpendicular to the wall. No way can they go through the capping. Usually I drill small holes and use wall plugs. When drilling I will definitely feel if the drill bit hits steel. I know this from practice, not theoretically.

A plastering trowel isn't razor sharp and its position combined with the direction it moves excludes damaging the wire. Yes, it moves up and down, but the position against the wall changes accordingly. Yes, you can damage  the wire if you wish,  but you have to try hard. Again, I've done a lot of plastering in my life.

Capping didn't disappear. It's being sold by all retailers. I my house, circa 1995, I do have capping under plasterboard on an external wall. If it's not required by regulations anymore, then it's because of RCD protection. However, even with protection, personally, I don't want to damage a cable accidentally, because repairing this is not easy as, AFAIK, you can't bury terminal blocks back into the wall and have either to add a junction box or replace the whole cable. Not sure about maintenance-free connectors and boxes, but burying any box IMO isn't a good idea.

Homer_home

@grumbler again this is not about you and your diy skills , these things are done so a person who is not diy savvy and has a go doesn't come a cropper, not everybody knows the difference between brick, plaster or a metal conduit when drilling and im not including the fact that they might not even be using the correct bit for the substrate they are drilling!

FYI its very easy to punch a nail through metal/plastic capping without even trying (how do you think the sparks fix them to the wall?)

grumbler

Homer_home said:

FYI its very easy to punch a nail through metal/plastic capping without even trying (how do you think the sparks fix them to the wall?)

Don't tell me that - I've done this many times myself (steel) - but not with the nails I use for hanging small things. And at the very beginning I said that plastic was useless in this respect.

For every military tank a weapon exists that can destroy it. A bicycle lock doesn't exist that can resist modern tools. This doesn't make them useless. The same applies to any protection - nothing is 100% reliable or fool-proof.

And again, it makes no sense to me to protect wires by galvanised(!) steel(!) capping from professional plasterers that can easily avoid reckless damaging (and only when applying basecoat) and ignore DIY idiots.