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Re: Compact fluorescent lamp life
Dave Gomberg wrote:
I bought a pair of Panasonic 96w cf tubes from AHSupply in Dec.
1999. This month one of them failed. They have been running about
hours per day split over two light periods per day (afternoon
thunderstorm). So that is about 8000 hours when the first tube failed.
But the surprising thing was that when I replaced the failed tube I
estimate the replacement was 2 stops (4x) brighter than the remaining
original. I thought someone had written that cfs didn't dim much, run
them till they die. Well I can tell you that with 5 hour on periods,
dim a lot in the first 8000 hours.
You cannot generalize a whole lot based on your experience. Individual
lamps of exactly the same type do not fail in a very predictable manner.
A significant percentage of lamps will fail long before their rated
life. Also other types of PCs will have much longer lifespans than the
96 watt CFs and also the lumen maintenance characteristics vary widely
from one type of PC to another. The fact that your lamps were on a 5
hour cycle should make no difference at all though. Most lamps are rated
on a 3 hour cycle.
I don't know anything about the lumen maintenance or hourly rating of
those 96 watt PCs. I wonder if your lamp performed up to specification
or not. 8000 hours seems pretty bad even for a PC.