In alt.engineering.electrical Paul M. Eldridge wrote: | On 25 Jun 2008 15:08:35 GMT, snipped-for-privacy@ipal.net wrote: | |>In alt.engineering.electrical Paul M. Eldridge 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: |>| |>|
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|>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.
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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: |
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| | The spectral performance of their TL930 and TL950 lamps can be found | here: | |
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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.