In article , bud-- wrote:
Don Klipstein wrote:

Now another idea: Compact fluorescents often do not do well in
bathrooms often used for short trips - unless they are cold cathode! And
cold cathode ones are dimmable.

Are all dimable CFLs cold cathode?

No. The dimmable version of Philips SLS 23 is hot cathode.

Roughly what happens to CFL efficiency as they are dimmed?

Dimable linear tube fluorescent balasts, IIRC, have a maintained hot
lead to power the filaments. What happens to efficiency as they are dimmed?

I imagine that there is some loss of efficiency when dimming a dimmable
hot cathode CFL, since I suspect the ballast provides some means to keep
the electrodes hot. I am not sure this is the case.

I expect any CFL will operate less efficiently when dimmed, but
generally only slightly less efficiently when dimmed unless the dimming is
very severe. I expect ballast losses to be a higher percentage of input
power during dimming. Incandescents lose effciency much more than
fluorescents do when dimmed.

- Don Klipstein )