"Michael D. Porter" wrote:
>
> The common units of brightness are lumens and candlepower. I suspect
> that MSCP stands for something like "mean standard candle power."
Close, it's "Mean Spherical Candle Power", meaning the candlepower is
averaged in all directions. Actually, the modern unit for candlepower
is called a 'candela', which is frequently abbreviated cd or mcd (for
milli-candela).
> Average life is a determination of the expected life of the lamp under
> the conditions described for its use--vibration during automotive use is
> probably figured into the average life figure. But, you're right--it's
> not very long. The actual life depends upon the quality of manufacture.
> We had a considerable problem with GE halogen headlights installed on
> some buses in the middle `90s. They were rated at 120 hours average
> life, but most failed at 80-100 hours. Lamps from Wagner, meeting
> similar specs, lasted hundreds of hours. I think "average life" ratings
> are mostly a CYA spec.
There are no standards for test procedure (or even a requirement that
they actually burn a bulb that long). I've noticed the opposite
characteristic with both home and automotive bulbs : GE bulbs last much
longer than Sylvania/Philips bulbs with the same lifetime rating. (I
used to work for Philips, our maintenance department was pissed when
Philips insisted we use Philips light bulbs, because they had to be
changed twice as often.)
Incandescent bulbs are always a trade-off between efficiency and long
life. The higher the efficiency (light output for power consumed), the
shorter the life.
I don't think you'll be too happy with your #52 indicator lamps. 30
hours is _way_ short for automotive use, and a #52 isn't all that
bright. If you can find them, #1446 is a better choice.
Digi-key will put you on their mailing list for catalogs free for the
asking. You can request a catalog, or search their on-line catalog, at
http://www.digikey.com/ .
Randall
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