In article ,
"** Frank **" writes:

Not good for filament lamps too. In fact, too many switching operations are

Actually, regular mains filament lamps don't care about switching,
and it doesn't shorten their lives. (This might not apply to high
current and halogen lamps, for which I haven't seen figures.)

not good for most things like computers, motors, TVs, etc. Switching
transients (both switching on and off) could have many thousand volts and
could draw 10x or more rated current across the device which could results
in electrical, mechanical and thermo shock. Note many lamp failures are at
the moment of switching either on or off.

That's why people think that switching shortens their life, but
it's a misunderstanding of what's happening. At the end of life,
lamps can continue operating for a few hours past the point where
they won't survive another switch-on. If you switch them off
during this period, they will blow at next switch-on, and in the
case of a lamp which isn't normally switched on for an hour or
more, it's pretty certain to blow at a switchon rather than whilst
running. However, this is independant of the number of times the
lamp has been switched on in the past and depends only on burning
hours. There are a number of applications where this effect can be
measured, such as continuously flashing signs which use regular
lamps, where life can be seen to depend on total burning hours
and not frequency of switching.

My own experience is CFLs (and Circle Lines) are much more susceptible to
switching than incandescent or the 4' and 8' fluorescent lamps. YMMV.

Assuming the most common fluorescent tube failure mode (electrode
emission mix all sputtered off), it depends on the design of the
control gear, and not much on the type of tube.

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