DIYbanter - View Single Post - Fitting downlighters in rockwool-insulated ceiling

wrote:

In article , Jack the
Lad writes

"The Question Asker" wrote in message
...

Its suggested by the manufactures to cut a circle of rockwool around the
downlighters. As for the heat loss I think it will be negligible unless you
are planning on installing hundreds of them, Also the back of the lights is
I think meant to be clear for about 10-20 cm

You need to construct a small box with air holes to fit over the back
of the fitment because in the future someone might otherwise disturb
the rockwool and thus cause a fire hazard.

Why the airholes? and what's wrong with an upturned clay flower pot?

You have to get rid of the heat somehow to avoid the cavity getting hot
enough to melt wiring insulation.

Heat will be lost via the plasterboard into the room, and upwards
through the flowerpot base - holes in it help if teh pot top pokes
through the insulation.

Experience shows a simple void of a sqaure foot or so is enough to leak
heat down through the plasterboard, but rockwool wrapped transformers
will fail :-)