PC Lifespans

["S. Hieber" <shieber at yahoo_com>]

Michael <Michael at Rubinworld_com> posted the following text 
in June 2002:

[Quote]
A friend was getting inconsistent information about his
compact
fluorescent lights.  I had heard that they maintain nearly
the same
lumen output for their entire lifetime, and my friend heard
that their
spectrum degrades.  I decided to ask aquatic plant
enthusiast and
lighting consultant David Lass what happens to the spectrum
and lumen
output of compact fluorescent bulbs as they age?  David,
who spoke at
AGA 2000 in Chattanooga, had this to say (bear in mind that
David uses
the term "lamp" to refer to the removeable, self-contained
system that
converts electricity into heat and light - sometimes called
a "bulb"):

 From: David Lass
 Sent: Thursday, December 20, 2001 3:36 PM
 To: Karen Randall; Michael Rubin
 Subject: Re: Looking for David Lass

 In answer to the question (and I just spent today at
Sylvania, so I
checked this out with them) The deal is that with any lamps
that use the
new triphosphor technology, which is T8's, T5's and compact
fluorescents
and power compacts, the lamp loses 10% of its lumen output
in the first
1000 hours of burning. For the rest of its life the lamp
maintains
approximately 90% of its initial lumen output. There is no
decay or
change of the spectral output of the lamp until they are at
the end of
their life.

 Typical life for compact fluorescents and power compacts
is around
10,000 hours, for T8's it is 20,000. To me this means that
you can run
T8's and T5's for 4 years plus,
and compact flos and power compacts for 2 years plus. Folks
trying to
sell HO and VHO lamps don't like this, since their lamps
have
tremendously steep degradation curves, and they do need to
be replaced
every year or so.

[end of quote]


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