Protecting cables that will be rendered over

16 Feb 2005
Reaction score
United Kingdom
I have read that if a cable is going to be rendered over with cement before being plastered the cable must be protected by galvo capping, is this correct as I had never heard it before?

I was going to chase the wall, drop the cables in oval conduit, then render the wall with cement, before final plaster.

Metal capping was advised because cement can damage PVC? Is this right, I'm sure I've seen plenty of PVC cabling buried in cement, let alone PVC conduit/capping as well.
Sponsored Links
Never heard of cement degrading PVC but if it did what's the problem, the capping is there to protect the cable from the plasterers trowel.
If you are really interested, contact the cement or conduit manufacturers.
The problem being that if it breaks down the insulation of the cable or makes it brittle it would be prone to failure. I realise that capping/oval conduit is only used to protect against plasterers trowel, but in this instance I think the galvo capping is meant to keep the cement from touching the PVC cable, and so stop the acids & alkalines damaging the cable.

If many others have rendered over bare or PVC capped cables without a problem then I won;t worry about it.
If it deteriorates the conduit, where's the harm. The cables wont be touching the cement so unlikely to be a problem, even if there is a degradation effect in the first place.
The only other advantage of capping cables is to allow new cables to be drawn in. Plastic conduit is easier to draw into than block on one side and galvo on the other.
Sponsored Links
Good point, hadn't thought of it like that. I'll just use normal PVC capping then, would use conduit but no need to chase due to being rendered then plastered, so might as well just cap over surface.
Hallsy said:
Good point, hadn't thought of it like that. I'll just use normal PVC capping then
You'll have no more luck drawing new cables through plastic capping than galvanised. If you want to allow for that possibility, conduit is the only way to go.
I used capping to save time as it was a bare brick wall that is going to be rendered then plastered, using capping means that I can just run the cables on the surface, due to the low profile of the capping the render will cover it. If I used oval conduit I'd have to let it in a bit. Besides I have tried pulling in old cables through oval conduit and it's not always as easy as you'd expect.

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links