On Oct 2, 6:28*pm, "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 ??

* * *Some web forum ?

He is right, the stresses involved in the turn-on of the bulb each
time is equal to several hours of continuous running. If you cycle a
bulb on and off every few seconds, the total on time before the bulb
fails will be only a few hundered hours for a 1000 hour rated bulb,