On 03/09/2014 23:25, 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???

Probably just ply impregnated / treated with flame retardants. It does
not make it fire proof as such (it will still burn if exposed to one),
but ensures it won't in itself sustain a fire.

I would have though plasterboard would be a quicker and cheaper option.
You can clad it in ply for easy "nailability" and cocoon it in
fibreglass quilt if you are really annal ;-)


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/