We have a facility with many fluorescent bulb ceiling fixtures. On occasion a bulb will burn out which is to be expected. The mystery – sometimes when I start to twist a bulb for replacement it relights and performs normally for an extended period. I wonder if this is due to corrosion in the fixture contacts (these fixtures are quite old). If that is the case is there something I can do to remedy the problem?
Thank you
poppi
Replies
old fixture
There is your answer. Old fixture mean magnetic ballast. A 60 cycle vibration form the old ballst and worn contact knife edges in the tombstone sockets. Over a period of time the bulb will rotate enough in the socket to be just a little out of alignment, partially breaking the contact point. The bulb starts to burn out or go dim. You come along and push it back to a good contact point and it picks up the full voltage from the ballast and goes bright agian. May last six day, six weeks or six months depending on other circumstances.
That is my experience with them over 26 years of facilty maintenance.
Sometimes just touching the glass will start them. That's even a bigger mystery.
Sometimes it's just a bad contact -- the lamps tend to "creep" over time and can eventually creep themselves right out of the sockets. Or the contacts just get oxidized and stop conducting. (You can help with the latter by putting a little dab of Vaseline or silicone contact grease on the pins before installing.)
But sometimes the lamp has gone bad, and it's just that placing your hand on it causes it to "ignite". It may run OK until it's turned off overnight and then it will fail again.
New sockets/tombstones
You can buy new sockets and replace the old ones. You can also buy new electronic ballasts, and replace those.
If the fixtures are hardwired it makes sense cost wise. Otherwise it is less expensive to buy completely new fixtures.