In article ,
Scion writes:
Andrew Gabriel wrote:

Retrofit CFL tubes are generally designed to run around 80-100C.
The electronics in the lamp base may be a little cooler, but since
they only have to last about 10,000 hours, the fact that they're
running near boiling point is just about viable. Each 10C temperature
rise generally halves the life of electronic circuits, so if you
operate it in a poorly ventilated fitting and it runs at 20C hotter
than it would in open air, the reduction to only 1/4 of the life
means that you'll probably start seeing some CFLs die due to ballast
failure before the tube wears out, and not realise the expected design
life across a reasonable sample size.


So if a lampshade (or fitting or whatever) is rated for a 60W
incandescent lamp, what wattage CFL would you feel comfortable putting
in?

Difficult to come up with a hard and fast rule.
Off the top of my head, I would suggest...

If the fitting is flammable (e.g. a paper lantern), stick with
no more than 1/4 of the max incandescent wattage.

If the fitting is enclosed (no convective airflow), probably stick
to no more than 1/4 of the max incandescent lamp. If it's all
fireproof materials, you could go higher if you don't mind reduced
lamp life.

If the fitting is well ventilated with convective airflow, can
probably go up to 1/2 the max incandescent wattage.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]