In article ,
Graham. writes:

Andrew, what are the "rules" about longevity claims for light bulbs?

It appears to me that if it's quoted in hours, it means continuous use

For fluorescent lamps, it is 3 hours "on" per switching.
I presume CFLs are the same, but I don't know that for sure.

Standard filament lamps - it makes almost no difference to life
how frequently they're switched.

but if it's quoted in years it's some unspecified daily use.

It usually says something about how many hours per day they
assume, but I don't think there's any standardisation for this
form of measurement.

I have even seen both figures on the same lamp without any explanation
why mathematically they didn't correlate.

--
Andrew Gabriel
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