Hi,
I've house remodelling underway and I'm looking at the electrics. The walls are planned to have 30mm thermaline basic (polystryene backed) plasterboard to improve the U value of the old walls and decrease the U of the new walls. I had thought that this would be method A, "enclosed in a conduit in an insulated wall". However, I now see that the full text says cables are just below the room surface (i.e. plasterboard) with a U > 10. Clipped direct also doesn't apply via the rear wall and text for that says masonry such as brick etc. excluding thermally insulating which I think means celcons which the new wall has. Old wall has some volcanic block which might just meet the wall resistance < 2 k.m/W (i.e. 0.5 W/m.K) in IEC 60364-5-52.
Do I have this right or am I missing something? If I use method 103 then I need 6mm2 for a 32A ring or 20A radial or 4mm2 if I make it a 20A ring (and I believe many sockets can only take 2 x 4mm2).
I also need new meter tails as CU is moving. There are 2 lengths of 20mm conduit which drop into the outside meter box and open into the floor void. These travel up the cavity for 1m or 1.2m maybe and the cavity is insulated. Again I was thinking method A but revising that I think I can still do it with 35mm2. Table 4DA1 says method C is 141A for 2 cables. I'll only have one per conduit because of the size so that is near enough 200A (141 x 1.414) which with 50% derate of 103 is 100A.
Any suggestions, other than drop the thermaline in favour of plain plasterboard which I'm considering......
I've house remodelling underway and I'm looking at the electrics. The walls are planned to have 30mm thermaline basic (polystryene backed) plasterboard to improve the U value of the old walls and decrease the U of the new walls. I had thought that this would be method A, "enclosed in a conduit in an insulated wall". However, I now see that the full text says cables are just below the room surface (i.e. plasterboard) with a U > 10. Clipped direct also doesn't apply via the rear wall and text for that says masonry such as brick etc. excluding thermally insulating which I think means celcons which the new wall has. Old wall has some volcanic block which might just meet the wall resistance < 2 k.m/W (i.e. 0.5 W/m.K) in IEC 60364-5-52.
Do I have this right or am I missing something? If I use method 103 then I need 6mm2 for a 32A ring or 20A radial or 4mm2 if I make it a 20A ring (and I believe many sockets can only take 2 x 4mm2).
I also need new meter tails as CU is moving. There are 2 lengths of 20mm conduit which drop into the outside meter box and open into the floor void. These travel up the cavity for 1m or 1.2m maybe and the cavity is insulated. Again I was thinking method A but revising that I think I can still do it with 35mm2. Table 4DA1 says method C is 141A for 2 cables. I'll only have one per conduit because of the size so that is near enough 200A (141 x 1.414) which with 50% derate of 103 is 100A.
Any suggestions, other than drop the thermaline in favour of plain plasterboard which I'm considering......