In article , Mike Ruskai wrote:
On or about Sun, 19 Aug 2007 04:07:06 -0400 did mm
dribble thusly:
On Sat, 18 Aug 2007 10:40:33 -0700, wrote:
I have understood that switching fluorescent lamps - tubes - on and
off was not a good idea and that they should be switched on and left
on. Unlike filament lamps which do not seem to mind.
Why do you say they don't mind? Haven't you noticed that they almost
always burn out at the moment they are turned on?
I was amazed no one had pointed out the error in that statement, and
was about to comment. Sure enough, last message in the thread, and
I'm scooped.
Most incandescents do not suffer significant wear from starting. What
happens is that an aging filament becomes unable to survive a cold start a
little before it becomes unable to survive continuous operation.
An incandescent burnout is generally from melting of a thiner hotter
section of the filament. Such a "thin spot" has a temperature overshoot
during a cold start.
Once a filament has a hot-running thin spot that becaomes unable to
survive a cold start, its hours are numbered. The thin spot suffers worse
evaporation because it runs hotter, and this condition accelerates worse
than exponentially, so the filament's days/hours are numbered once it is
in bad enough shape to be unable to survive a cold start.
- Don Klipstein )