Another garden room wiring question

Question

Despite the weather I have built the shell of the garden room and will sooon be ready for the electrician. 
 We agreed that the SWA would run up the outside of the cladding to a junction box then T+E from there through the cladding and SIP wall, which comprises polyurethane insulation sandwiched between two sheets of OSB. I will be drilling the hole for the cable and would like to run it rhough a pipe, e.g. 22mm plastic pipe. Is that acceptable, if not what else could be used? 
 Mike

David Stone · Accepted Answer

What size SWA is it? I suppose you are looking at a 4mm2 or 6mm2 size for some heating etc. This will easily travel through a 35mm sweep elbow (plumbing) which you can seal through the Tyvek with silicone. It is easy to drill these panels, use a long drill to make a centre hole right through. Use a suitable hole saw on each side to drill the wafer board and into the PU. Finish the PU hole with a chisel or gouge to just fit the pipe. At the inside end of the pipe fit a cap with a hole to fit the SWA, and seal with silicone to keep insects out. The elbow prevents any water ingress and looks quite tidy. Do not seal the outside end of the pipe, you want the ventilation. You could run pipe right down the wall if you prefer. I assume you are tiling the outside, or perhaps a brick skin. This can easily be built around the pipe which will then be hidden or run the SWA behind the tiles or bricks.

Another garden room wiring question

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