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Re: [Phys-l] CFL's Read the fine print.



Here in southern California, Southern California Edison is providing subsidies to certain retailers (Drug Emporium is one) for CFLs. I have been purchasing most of my CFLs there for 50 cents each (75 watt equivalent and 100 watt equivalent bulbs only).

I've found that the ratings are reasonably accurate. 4 hrs per day X 365 days X 5 years = 5840 total hours. Ordinary incandescent bulbs generally are rated for 1000 hours or less. Some of the halogen bulbs are good for 2250 hours (but cost more than twice as much as a regular incandescent).

High temperature will reduce the lifetime of CFLs, so they should not be run in enclosures with poor heat transfer. However, I run many of them in enclosures (thin glass globes) with reasonable heat transfer and find that their lifetimes typically are close to the rated value.

(Complete disclosure: I own Edison International stock. Edison International is the parent company of Southern California Edison).

Mark


-----Original Message-----
From: phys-l-bounces@carnot.physics.buffalo.edu on behalf of William Maddox
Sent: Fri 5/18/2007 6:39 AM
To: Forum for Physics Educators
Subject: Re: [Phys-l] CFL's Read the fine print.

From: WC Maddox

This may explain some of the variation in how long CFL bulbs last: On
a piece of cardboard where you would see it if looking at package in
store it states " LASTS 5 YEARS" in orange letters about 3/8" high.
On the back in black print about 1/8" high it states that the 5 years
is based on a average use of only 4 hours per day. You are also
warned in small print not to use it in an enclosure and that it is
guaranteed to start only down to 5 deg F.

What's with the 50 cent CFL bulbs some have mentioned? Around here
they are closer to $5.00. I wonder how long a subsidy like this could last.

Does anyone have experience with using halogen screw in bulbs for
home use? I wonder how they fit into question about cost, power use,
lifetime, brightness, & color.

End Message



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