| On 25 Jun 2008 15:08:35 GMT,
[email protected] wrote:
|
|>
|>| As with the halogens I identified above, incandescent lamp life is
|>| based on the same 50 per cent rule -- that is an industry-wide
|>| standard. For a graphical representation of this, see page 2 of:
|>|
|>|
http://www.sylvania.com/content/display.scfx?id=003694068
|>
|>Then something's out of whack somewhere. I see far more than 50% of bulbs
|>last beyond 750 hours of usage. That didn't catch my attention before as I
|>did not assume something like the 50% basis.
|
|
| Hi Phil,
|
| A couple possible explanations. One is that although a standard
| 100-watt incandescent has a nominal service life of 750 hours, the 25,
| 40 and 60-watt versions are typically rated at 1,000 hours. Secondly,
| manufacturers have been introducing products that are shifting the
| balance between higher lumen output and longer life further towards
| the latter, so you may have noticed the elogic lamps in the above link
| have a rated life of anywhere from 1,125 hours (95-watt) to 2,250 in
| the case of the 40-watt equivalent. Line voltage and the use of
| dimmers can also dramatically affect lamp life.
I looked at my spare lightbulb supply today. Most did not have boxes. But
one set still did. These are 25-watt and show 2500 hours.
http://phil.ipal.org/usenet/aee/2008-06-26/s6301196.jpg
So I guess I should raise the issue not specifically about 5000 hours, but
about the 50% basis.
| If you're extremely fussy about spectral distribution, I don't see any
| clear winners. Philip's new MasterColour Elite ceramic metal halide
| lamps are arguably the very best the industry has to offer; you can
| see its distribution graph on page 2 of the following spec sheet and
| draw your own conclusions.
|
| See:
|
http://www.nam.lighting.philips.com/us/ecatalog/hid/pdf/p-5899.pdf
|
| The spectral performance of their TL930 and TL950 lamps can be found
| here:
|
|
http://www.nam.lighting.philips.com/us/ecatalog/fluor/pdf/P-5037-D.pdf
I have not seen good light from MH lamps, either.
A better fluorescent formulation could fix FL lamps. But it would require so
many different compounds to make an even spectrum that it would most likely
be prohibitively expensive. I have found that LEDs come in enough discrete
wavelengths that this might work. But they degrade at different rates over
time, and keeping it in color balance would be hard.