DIYbanter - View Single Post

Don Klipstein

In ,
wrote:

The fluorescent shop light in my garage (2 bulbs) stopped turning on
via the pull-chain. For a time, the bulbs would light if I twisted
them a bit, but then that stopped too. I removed one of the starters,
thinking it might need replacing, and discovered that as I removed it
the bulb lit. Now I'm able to light both bulbs by briefly inserting
and then removing the starter for each bulb. The bulbs light as the
starter is being removed. What gives? And will new starters restore
normal function, or is something else wrong with this lamp?

Are these 4-footers? You have 4-footers with starters?

The starters are probably bad/marginal (FS-4 for 4-footers). Or the
bulbs may not be compatible with your particular starters in the cold -
the starters could restart conducting. See if the starters are FS-2 -
those are for shorter bulbs and normally don't work right with 4-footers.

If removing the starters allows the bulbs to light, try putting a
starter back in when the bulb is lit. If the bulb goes out, the starter
is probably stuck. On the other hand, the bulb's electrical
characteristics may be changing as a result of the bulb being close to
end-of-life.
But I think it is unusual for both bulbs or both starters to be doing
this simultaneously - it may be cold weather (new starters may improve
this) or the ballast.

Beware that starters with stuck innards may cause the ballast to
overheat. I am aware of a fire that started that way (the ballast had to
be of marginal design).

Note that bad starters can be hard on bulbs and bad bulbs can be hard on
starters. Your bulbs could have suffered wear from having their filaments
being kept cooking by bad starters. You might need to replace both the
bulbs and the starters.

I would avoid those 34 watt "energy saver F40" bulbs - they tend to be
crankier and sometimes don't start as easily. They are also dimmed by
cold more than true 40-watt F40.

Other factors that could affect starting: The fixture may not be
properly grounded - this affects electric field distribution within bulbs
that are trying to start.
But if this has not happened all along or annually or
whenever certain weather occurs, then lack of proper grounding is not the
whole story - the rest of the story may be a thin film of slightly
conductive dirt on the bulbs. That often gets worse when humidity is
higher. I have heard of a few cases when cleaning the bulbs fixes things.
In extreme cases (usually in coastal areas), bulbs have refused to start
even with proper grounding due to a film of slightly conductive dirt on
them.

I would go with the others advising to replace the whole fixture with
one that has F32T8 bulbs. A 4-foot shop light with starters is so old
that you will probably find such a new fixture better in a few ways.

I would avoid cheap shop lights with T12 bulbs. Many of those have
"residential grade" ballasts, which are often stool specimens that often
seriously underpower the bulbs and have low energy efficiency as far as
ballasts go.

- Don Klipstein )