Cables in cavities

[Just]

Hi, I have a a job to do on a single story building standard construction with loft access. I need two outside sockets on a new circuit, I can run easily from the board to the location but don't want to drop inside and re-plaster.I haven't needed to in the past, is it bad practise to drop down the cavity are there any regs against this? Any tips for feeding past insulation if allowed would be appreciated? Alternatively have I got to chase out on the plastered internal wall or are there any neat external solutions?
Thanks for the advice.

 

[rocker]

You shouldn't go down the cavity. This is because if they have wall insuation this is often made of polystyrene bals which as wel all know damage PVC insulation. In this situation I would go straight out and cable down the wall, using suitable cable or capping.

 

[Just]

Okay thanks, it is a relatively new extension and so the the insulation is fibreglass?

 

[chris gray]

just use some 20mm conduit outside.