Re: Durability of small screw in flourescents...?

On Fri, 27 Mar 2009 04:29:05 -0700 (PDT),
pheeh.zero@xxxxxxxxx wrote:

On Mar 27, 3:59 am, dkco...@xxxxxxxxx (David Combs) wrote:
In article <30d99e04-b03c-438b-9d0e-a02cef7e7...@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,







JIMMIE  <JIMMIEDEE...@xxxxxxxxx> wrote:
On Feb 25, 6:54 am, ransley <Mark_Rans...@xxxxxxxxx> wrote:
On Feb 24, 4:03 pm, Kenneth <use...@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

Howdy,

We use many of the (currently popular) screw in fluorescent
bulbs.

We often get 'em at Home Depot, and they have a seven year
replacement warrantee.

None have lasted more than two years, and, to date, we have
received on the order of two dozen as warrantee
replacements. The manufacturer does not even ask that we
return the failed bulbs.

More than a few have failed in less than a month, and since
the first of those, I mark 'em with the date of installation
and the date of failure.

When I first noticed the very short MTBF, I called the
manufacturer's tech folks. The first thing they asked was
for a description of the fixtures that hold them. They are
(mostly) ceiling cans of the sort that are closed on the
top, and open on the bottom. When I provided that answer, I
was told that such an installation should not be affecting
the length of life of the bulb.

So, I have become curious...

How long do these things last for others out there?

Many thanks,
--
Kenneth

If you email... Please remove the "SPAMLESS."

Maybe you have voltage problems and surges, but heat is the likely
cause.- Hide quoted text -

- Show quoted text -

Ive done some failure analysis * on some of these and found its the
electronics that usually fails. I dont doubt that they would work for
7 years of normal use if the elctronics wasnt being operated at its
limits.

* I cracked them open to see what smoked.

Electronics are where?  In the base of the bulb, I guess.

So, when bulb is in ceiling light, pointing straight down,
heat goes up to -- the electronics?

----

Used to be that with fluorescents (long bulbs in office
ceilings) they would leave them on 24/day.  Reason:
it was turning them on, the jolt to the various
components, the sudden heating from room-temp to whatever,
that was said to cause them to fail.

(1) Is that STILL true?

(2) Also for those new screw-ins?

If so, then it pays to keep the things on *forever* --
the electricity using being low enough to cost (I guess?)
over a year or two less than the cost of the bulb. (true?)

Anyway, you now have an "engineering" decision --
two things working against each other:

   keepin on, to keep from burning out (from startups)

   heat from doing that, cooking the "electronics" (such as
     they are?)

Thanks!

David

I have some CFLs in totally enclosed explosion-proof fixtures...but
they are "on" 24/7 and have lasted more than 2 years.
So yes, on/off cycles will shorted their life-span.

Howdy,

I'm the OP...

Your comment, together with others here have really helped:

We live in a rural area, and heat geothermally.

Those two aspects of our situation may seem unrelated, but
they are indirectly related.

Our electrical supply is (how to put this delicately...)
something less than stable. There are all sorts of voltage
fluctuations evident.

On top of that, our well pump is about the size of a
locomotive, and when it kicks in, there is a very obvious
voltage dip.

My strong suspicion is that these fluctuations are the cause
of the bulbs' shortened life...

All the best,
--
Kenneth

If you email... Please remove the "SPAMLESS."
.

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