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

[Roger Haar <haar@physics.arizona.edu>]

Hi,

	A couple of additional data points:

	I have a CFL in my dusk to dawn light outside my garage.  It has been 
going strong for about 3 years now.  This is one place a CFL really 
saves, because over a year it is on an averages 11-12 hours/day.

	Here at the University of Arizona, they have been replacing older 
lights with modern ones.  They are paying for it out of the savings. 
About 7-8 years ago they replace the most of the fluorescents with 
better ones and then when the T-8's came out about four years ago, they 
replaced the lights again.  The T-8 ( The 8 is the diameter of the tube 
in 1/8-ths of an inch.)  run cheaper, last longer than the old units, 
have an electronic ballast so they flash at about 20,000Hz, and have 
better color.  In one hallway the last light was one a different circuit 
and was changed later than the rest of the lights.  With the new T-8's 
in place, that end bulb clearly gave off an ugly green tint.

	There seems to be some electrical oddity in my office.  Twice in  four 
years the T-8 ballast have failed.  Someone who had occupied my office 
30 years ago, was talking to me when they fixed it the second time. He 
said, the lighting failed frequently when he had my office.  The repair 
guy said that there are a number of rooms on campus, which their records 
indicated have a high failure rate.  But it could just be statistical 
fluctuations.

Thanks,
 Roger Haar
  U of AZ

Ian Collier wrote:
> That five years at 4 hours per day translates to about 7000 hours.
>
> Seems pretty realistic for most of the bulbs in my home - as opposed to my workplace.
>
> Most incandescent bulbs have lifetimes typically under 1000 hours. (Dramatically less if they are over volted for more efficient light output.)
>
> Of course if you are in an environment where you pay someone actual money to change bulbs for you (ie almost any workplace) having to do that 5-7 times less often pays for CFLs all on its own.
>
> --Ian
>
> ----------------------------------------------------
> Ian Collier                      ian.collier@mac.com
>
> +44 (0)118 984 2462        (cell) +44 (0)7866 510075
> ----------------------------------------------------
>
>  
> On Friday, May 18, 2007, at 02:41PM, "William Maddox" <maddox@physics.Auburn.EDU> wrote:
> > 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
> >
> >
> >
> > End Message
> >
> >
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