Correct me if I'm wrong but as I remember
when fluorescent lamps went into common use
they used to say that they would last twenty years.
Now they're saying the same thing about LEDs.
I was at a store and saw these LED light fixtures,
so I asked the guy if he sold the LED light bulbs for them.
The salesman said that the LED light bulbs for the fixtures weren't
replaceable and that the LEDs would last twenty years
and I wouldn't need to replace them
but would have to replace the whole fixture when that happens.
I bought this cheap multi LED flashlight a few years ago
and one of the LEDs has been going out every few months
until now I only have one or two of them left that still comes on.
Your memory is accurate; but measuring fluorescent lamp life in years is
incorrect unless the lamp is burned continuously or you know how many
hours/day it's operated. Fluorescent lamp life is rated in hours so is the
lamp operated for 1 hour per day or 5 or what? Manufacturers also found out
early on with fluorescent lamps that starting the lamp reduces lamp life.
More starts = less life, so now manufacturers rate lamp life at (usually) 3
We're going through the same process with LEDs. They're capable of lasting
for many years -- think of the LED indicators in cars, household appliances
and the like; but every LED bulb or fixture is different and may overheat or
overpower the LED so it fails early. Some people have found that LED bulbs
don't last very long if they put them inside enclosed fixtures where heat
can build up, for example.
The DOE is testing the Philips "L Prize" LED bulb and recently reported that
the 200 bulbs on test have now burned for 25,000 hours with no failures and
no loss of light output. Maybe that's where the "25 years of life" came
from because, typically, a bulb in a home is usually burned about 1,000