My conservatory installation seems to be turning into the installation
from hell. The current difficulty is with regard to the ridge lighting
(4 downlighters).

The electrician, who's supposed to be coming to fit them on Monday,
admits he's never fitted them into a conservatory before. The
conservatory supplier may also never have fitted them before, but I
can't get hold of anyone there. The lights are 50mm LV 20w halogen
eyeball spots, and the instructions specify 160mm void depth. How do
you fit spotlights into a conservatory ridge if they need that kind of
depth? The mains voltage variant of the same light specifies a smaller
void depth (140mm I believe), presumably because it doesn't need the
space for the transformer, rather than because they produce less heat.
(If I understand it right, 20w of heat is the same whether its LV or
240v?)

Does the heat dissipate through the aluminium? Is that a good idea?
What happens to the uPVC if it gets too hot?

I'd like to be armed with some knowledge about this when the guy from
the conservatory company calls me on Monday am to reassure me that
they know what they're doing with regard to this. Should they be
fitted outside the ridge, rather than cut out to fit into it, so that
the heat can dissipate into the air of the conservatory itself. How do
these usually work?

Thanks

Brian