On Wednesday, September 3, 2014 11:25:53 PM UTC+1, Tim Watts wrote:
I will be wiring lighting soon (hooray) and I have determined the way I
want to do it is bring all cables back to 4 sets of places in my dormer
- near the ouside where the cable trays run.
Each of these 4 locations will be a "cupboard" on the dormer uprights in
some semi dead space (where the ceiling is low) but usefully accessible.
I'm not a fan of junction boxes all over the place even if that's how
it's usually done.
I will stick SELV transformers here too.
There'll be a 5th cupboard housing a small sub-CU for all external
circuits (sheds, outside power, pond, whatever) fed by a distribution
circuit from an MCB in the main CU.
So it seems sensible to make these cupboards, which are mounted on
timber framing in a very wooden part of the house, a little more fire
resistant - just in case a SELV transformer goes ape, or a JB gets hot
from a fault.
I was thinking ply lined inside with 12mm plasterboard. Simple. All we
are talking about is if something gets hot, as in ignition point of
paper type hot and melts, that it is unlikely to set the enclosure alight.
Or is there a better/easier way? I've seen a reference to fire resistant
ply:
http://www.alsfordtimber.com/sheet-m...d-plywood.html
What does that mean???

Don't forget ventilation needed - vent through a metal tube to stop fire spread. Food cans wired together perhaps?


NT