Lyndhurst Garden House

Lyndhurst Garden House
Lyndhurst Garden House

Sunday, November 17, 2013

LED lamp runs 20 years? But only 2000 hours?

I replaced the 3W LED lamp in the wood shade pole lamp I use for background lighting in the King's Room (nice for watching TV) with a 7.5W incandescent.  The 7.5W incandescent gives much more pleasant background light, which seems to require no more than 50 lumens.  The LED lamp emitted 100 lumens, as I found looking it up online.

But then I noticed something peculiar in the specs.  The bulb is said to be good for 20 years at 2.7 hours a day.  Since I run this lamp at least 7 hours a day, I guess that would mean less than a 10 year lifetime.  That isn't what I'd consider a 20 year lifetime.  Who runs a lamp for only 2.7 hours a day?

But it gets worse.  The lamp is also shown as having a 2000 hour lifetime.  That doesn't add up if you can run it 2.7 hours a day for 20 years.  The latter would require this many hours:

365 days/y * 20 yrs * 2.7 hours/day = 19710

That's more like a 20,000 hour lifetime, which is a lot more than the 1000 hour lifetime of a typical incandescent.  But 2000 hours would be only twice as much as the incandescent.



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