Cables in Cavity Walls

Postby GLW » Sat May 12, 2007 6:16 pm

I'm currently in the process of re-wiring a 1930's house. I've been replacing some of the ring main cables and sockets, by running the cables along the same routes (mainly down the cavity).

While doing some other research on the interner, I've come across some references that would indicate that cables now cannot be run down cavities. Is this the case? The reason that I've used these routes is that I could not dream of trying to channel a conduit beneath the ornate plaster cornice and picture rails that I have in the house!

Would encasing the cables in some flexible conduit down the cavity suffice?

Many thanks

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Simply Build It

Postby sparx » Sun May 13, 2007 9:41 am

Hi, 2 reasons given for not using cavities;
first is building regs. if cable touches both inner & outer walls then damp can bridge across, which is why wall ties have 'drip point' in centre.
Second reason is if cavity foam insulation done later it does attack the polymere in PVC outer cover and makes cable go stiff as a board which then leads to vibration cracking of insulation allowing damp into cable & lowering of insulation value.
your idea ok but not sure of practicality of introducing flex. conduit into wall,
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