Re: the light bulb police are coming

[Marc_F_Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx>]

On Wed, 14 Mar 2007 21:06:25 -0400, ken <omd-nospam@xxxxxxxxxxxxxx> wrote in
message  <45F89C11.1000408@xxxxxxxxxxxxxx>:

>Marc_F_Hult wrote:
>>
>> On a trip to my local Home depot, I recently bought some of their new line
>>of n:Vision Compact fluorescent lamps ( CFL ).
>>
>
>> -- Dimmable (but not to zero and not officially)
>
>be interested in hearing any observed lifespan issues.
>
>dimming may "work", but what does it do to life expectency of either the
>electronics or the bulb chemistry? any weird RF interference when dimmed?
>
>why wouldn't they advertise dimmable if they were dimmable?
>
>   -ken, pretty much waiting for dimmable cfc to appear in local stores


The 'officially' dimmable CFLs that I have will dim to about 6% of full
output (= 4 'stops' in photo parlance) as measured by a Zone-VI-modified
Pentax spot meter and(or) Nikon D200 spot meter. They exhibit no untoward
behavior when the light extinguishes -- it just goes out.

The 'non-dimmable' n:Visions CFLs I measured will dim about 3 stops (12% of
original) perfectly normally and usefully and then begin to flicker, first
almost imperceptibly, then irritatingly,  then on-off like the flash to 100%
of an incandescent that is under X-10 dimmer control before it dims. (You
know what I mean if you've dimmed X-10 WS-467s.

With a lighting system with a user-definable dimmer curve (eg DMX512), one
could simply exclude the 0-15% power range and have a perfectly useful dimmer
(with lifetime issues unknown). With _dependable_ preset dim (in my case,
DMX512 and INSTEON), you could use them usefully dimmed (again, without
addressing the issue of lifetime).

I did let one go over light in a distinctly irritating (to me) flicker and
buzz mode (~ 10% INSTEON dim level) with no apparent ill effects to the lamp.
Not a very rigorous test, but as they say, one data point is infinitely more
than no data points ;-)

4 stops is equivalent to being able to turn on any number between 1 and 16
lamps (1:16). 3 stops is a range of 1:8. I suppose that some folks might feel
shorted if the lamps were designed to extinguish to zero at 1/8 power instead
of 1:16th.

At first blush, the CFLs I tried have a fairly linear ratio of watts consumed
:light  output. In contrast, incandescent lamps  have notoriously low
efficacy when dimmed.  The perennial CFL basher in this news group  has said
that he gets years of life from incandescent bulbs because he keeps them
dimmed. Saving a few pennies on the lamps costs him many dollars in wasted
electricity. With incandescents, if you want less output, the best course
from an efficacy standpoint is to replace a the lamp with a lower wattage
one.

CFLs come in a much wider array of nominal color temperatures than
incandescent lamps. A high CRI (Color Rendition Index) 'daylight' fluorescent
is much preferable to any incandescent for critical work involving color
evaluation. The n:Vision Compact fluorescent lamps at Home Depot come in
daylight (nominal 5500K) , bright white (3500K) and warm (2700K).  Geezers
may like me may remember that the bluest conventional incandescent
photofloods (type A) are 3400K. Conventional high-wattage halogens are
3200-3000 IIRC.

Compared to incandescents which change greatly in color temperature when
dimmed, CFLs seem to maintain a very constant color. When you dim them they
just get dimmer instead of turning a yellow/orange that is undesirable for
many purposes -- and desirable or at least expected for others.

HTH ... Marc
Marc_F_Hult
www.ECOntrol.org