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Re: [Phys-l] CFLs



I have bought some CFL's that claimed that they were for three position switch situations, (the lamps where the middle position is typically the brightest. I've wondered what, if anything, is different about them.

_________________________

Joel Rauber, Ph.D
Professor and Acting Head of Physics
Department of Physics
South Dakota State University
Brookings, SD 57007
Joel.Rauber@sdstate.edu
605.688.5428


-----Original Message-----
From: phys-l-bounces@carnot.physics.buffalo.edu [mailto:phys-l-
bounces@carnot.physics.buffalo.edu] On Behalf Of Edmiston, Mike
Sent: Tuesday, April 07, 2009 3:50 PM
To: Forum for Physics Educators
Subject: Re: [Phys-l] CFLs

I've had mixed luck with the lifetime of CFLs. I believe they have the
best likelihood of long life if they are installed base down (so the
electronics operate at lower temperature), and with a lot of air
circulation (not a fully enclosed fixture).

I haven't kept written records, so my recollections are subject to
significant error, but I believe the only CFLs that have lasted the
stated lifetime in my house were those that were installed in standard
lamps (like a table lamp) with lots of air circulation, and with base
down. Sideways installation is not too bad (I have some ceiling
fixtures that hold the bulb sideways). Base up is not as good. Base
up
and totally or partially enclosed is quite bad.

Enclosed fixtures are not as bad if they are large.

Also, you should know there have been fires that were cause by putting
a
CFL in a lamp with a three-way switch. The base of the CFL is not
supposed to touch the third contact in the socket of a three-way lamp.
However, if it does, it causes a short circuit. If the circuit breaker
doesn't blow quick enough, and the lamp cord is just 18-gauge zip-cord,
the short can start a fire in the lamp cord. I also saw one in which
the fire started in the socket itself. So be careful putting CFLs in
three-way lamps.


Michael D. Edmiston, Ph.D.
Professor of Chemistry and Physics
Bluffton University
Bluffton, OH 45817
(419)-358-3270
edmiston@bluffton.edu
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