On 7/31/2017 2:12 PM, Keith Nuttle wrote:
I am posting this to the woodworking group because wood workers know a
lot about everything. ;-)

I am a volunteer at church and one of things that I do is change the
florescent lights when they die. Most of the fixtures are four tube
fixtures.

Is there a test to tell if a Florescent light tube is bad and needs to
be replaced, or the light is not working because its companion is dead?

I have struggled with this. Sometimes when one of the tubes is replaced
the other seems to start working. So it would be nice to test the tube
to see if even though working it should be replaced.



Being in a church I'm going to make an assumption that the lamps are
T-12. That means they are the 1" wide lamps which are becoming obsolete
and/or expensive to purchase. If they are the T-12 and you will replace
with the same, then change both lamps instead of one. I say both lamps
since usually they have two ballast per 4 lamp fixture but if it's one
ballast, then change them all.

Today's universal T-8 ballasts are much more efficient and when one lamp
fails, the others will still function. Then you can just replace the
failed lamp. When one T-12 lamp fails, the others on the same ballast
will stop functioning but resume when the failed lamp is replaced.