On Fri, 24 May 2013 10:48:56 -0400, "=" wrote:


"Robert" wrote in message
...
On Apr 26, 11:24 am, "Pete C." wrote:


So LED lamps are about 20% cheaper than CFL

For both LED and CFL, the main failue mechanism is the electronics
that are used to change the 120V to the higher, or lower, voltage
that these lamps actually use....
The light source themselves are very long lived. The electronics
are
not. A power spike that an incandescent can ignore can easily wipe
out the high voltage inverter in the CFL base, or the current
limiting
capacitor and reverse diode in the LED base.

You have to look at the entire assembly, and not just what the
manufactures publishes as "lamp life"..... You will NEVER get the
claimed numbers if you live in a place where there are power outages,
thunderstorms, or higher temperatures....

The above is a good review of the situation. I can add that the rated life
for LED bulbs is still a made-up number based upon what the marketing
departments of the manufacturers feel they ought to say and the length of
warranty that the company wants to (or can afford to) honor. Rated life is
therefore set motr by the competitive environment, not by actual tested
performance.

Which means that the number is set to make them look good, not as any
measure of reality. Added to this is the life of the LEDs themselves
are reasonably well known AT SOME TEMPERATURE. *IFF* the manufacturer
did their job in designing the heat sink, it may even mean something.
How do you know?

But when just incandescent lamps were available, the situation was not much
different. Manufacturers have always been able to make incandescent bulbs
last for 1000 - 5000 hours and they design their products to trade off
performance against what they think they can sell. What they can't control
are the user's socket conditions which might subject the lamp to high
voltage, voltages surges or physical shock and vibration which can kill a
filament bulb in short order. As a lamp engineer told me once, "few
incandescent bulbs die a normal death where the filament evaporates until it
breaks. Usually, some jolt -- physical or electrical -- takes them out
early".

Sure, but that's normal design and all well known. IME, incandescent
bulbs last much longer, in most fixtures (some are bulb eaters), than
the ratings. Comparing different technologies, and in particular how
they will respond in different applications, is worse than apples and
orangutans.