On Wed, 3 Oct 2012 09:28:13 +1000, "Phil Allison"
wrote:

"Graham."

An incandescent light bulb is a good example, If it lasts 1000 hours
when run continuously, its life will be considerably shorter if run
(say) 4 hours a day and the time it is on added up.

** Where ever did you get that nonsense from ??

It's not nonsense. The inrush current of a cold filament can shorten
the filament life. That's why light bulbs usually blow up when you
turn them on, not while they're running. The induced magnetic field
also tends to "twang" the filament, which can break the filament if it
were somehow mechanically weakened.

While attending kollege in the 1960's, I worked for a short time as a
non-union projectionist at a movie theater. Besides babysitting the
projectors, I had to deal with the flashing light bulb marquee. I
vaguely recall that there were something like 2000 40 watt light
bulbs. Roughly once per week, my job was to replace the blown bulbs
from a rickety pre-OSHA 20ft wooden ladder, sometimes at night. I
didn't keep count, but every week, we would lose about 20 light bulbs.
Doing the math, that means after about 2 years, ALL the light bulbs
would have been replaced at least once. At 8 hrs run per day, that's
800 hrs lifetime which isn't all that great, especially since we were
running the bulbs at reduced voltage to improve the lifetime. We used
the same bulbs in the theater foyer and lobby, where they were NOT
cycled on and off like the flashing marquee. I rarely replaced those
bulbs and they seemed to last forever.

Some web forum ?

If you repeat something often enough, it eventually becomes dogma.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558