I have flourescent lights in my kitchen. There are three units within
the recessed ceiling with a plastic cover over the entire thing. There
are two switches, one on each side of the kitchen to turn on the lights.
These lights sometimes take a long time (minutes) to turn on when
either switch is used. I haven't been able to narrow it down to the
switches as being the culprit so I must assume the ballast is the cause.
Can anyone offer any advice on how to troubleshoot any further and
where to find the ballast? Does each flourescent unit have its own
ballast or can there be one for the whole system? Why would all three
be affected if there are separate ballasts? I'm still suspicious of
the wiring myself.
fluorescent fixtures can be affected if they're not grounded. There is
usually one ballast per every two lamps. A two lamp fixture has one ballast
and a four lamp fixture would have two ballasts. This does not hold true for
electronically ballasted fluorescent fixtures though. As the lamps, and
ballasts get old, it becomes more difficult for the lamps to light. Loose
sockets and lamps not inserted properly will also cause problems
Why do you suspect the wiring? Do you think the wire has a kink and the
electricity is having a hard time passing through it? It does not work like
a garden hose. I've replaced hundreds of tubes, many ballasts, and have
never had a wiring issue.
I suspect the ballast. It is usually under a metal housing on the fixture.
It may be cheaper to replace the fixture than to buy a replacement part. It
will also have a nice bright cover instead of yellowed plastic if yours is
some years old. Check before you buy.
If 3 fixtures are all going bad, I would more suspect:
1. The lamps ("bulbs") are going bad, probably as a result from normal
death from some combination of operating hours and number of starts.
Look for "bulbs" blackened at one end (less frequently both ends). And
in many fixtures, one "bulb" going bad can impair another (from them
sharing a ballast).
2. Search for lack of proper grounding and "hot-neutral reverse".
Normally, it is specified for the "bulbs" to be within half an inch of
grounded sheet metal. This affects electric field distribution within a
"bulb" that is trying to start. Lamps/"bulbs" may tolerate lack of proper
grounding for a while and can get cranky after something like a few
thousand operating hours or a change or two of seasons.
Same story for hot/neutral reverse.
3. If all else fails - try cleaning the bulbs. Sometimes, expecially in
coastal areas, the bulbs can get a thin film of salty dust, and when the
relative humidity gets past something like 60 or 75 percent or whatever
this dusty film can get conductive enough to screw up the electric field
distribution within a "bulb" that is trying to start.
4. More remote possibility - the ballast was replaced with one that has a
different wiring diagram from that on the replaced ballast and there is a
minor wiring error that is mild enough to sometimes be tolerated (such as
when bulbs are in newer condition).
5. Another less-common one - old rapid start ballast "eats bulbs". There
is a less-common failure mode of many older rapid start ballasts whose
main symptom is that lamps/"bulbs" last only a couple thousand or a few
thousand operating hours. However, it is very unlikely that 3 fixtures
out of 3 will go from "good" to "bad" in just a year or two for this
reason. If you get sufficient evidence that this is the problem, replace
the offending ballasts or get new fixtures.
6. One thing to watch for - mismatch between lamp ("bulb") and ballast.
For one thing, there is quite a variety of 4-foot fluorescents, even at
least 3 wattages of T12 (1.5 ich diameter) ones with 2 pins at each end.
Know what the fixture is supposed to take, and in case of any doubt read
the ballast label. Incorrect lamps/"bulbs" have a high chance of reduced
life, and in some cases a mismatch is hard on the ballast (especially T12
4-footer of 25 or 34 or 35 watts or "energy saver" used with a ballast
rated for 40 watt T12 but not lower wattages of T12).
7. Check if the ballast is one of those "residential grade" ones that I
like to call "stool specimens". Those are widely regarded as giving less
than full light output and sometimes regarded as prone to making
lamps/"bulbs" die sooner than they should, especially if the "bulbs" are
T12 ones of 34, 35 or 40 watts as opposed to the 25 watt ones made for
such atrocities of cheap fixtures. And I suspect that 34 and 35 watt ones
will fare worse than the "more normal" 40 watt ones with these ballasts
because 34 watt T12 wants more current to run well.
Best way to tell - the usual "stool specimen" "residential grade"
balllast for 2 4-footers is in a package something like 1.5 inches less
long than "The Real Thing". Get to know what both look like! Also, it is
my impression that the ballast is not as good when it comes in a
cheap "shop light" fixture that is specified to be hung by chains and not
to be flush-mounted on a ceiling or along a beam.
8. 34 watt T12 fluorescents sometimes just don't do well (especially in
colder areas) by just being "generally crankier" than the true-40-watt
ones. This is not true of 32 watt T8 (1 inch diameter), which requires a
different ballast anyway (at least generally when the ballasts are of
brands that have been more held in higher regard since T8 started to get
- Don Klipstein ( firstname.lastname@example.org)
Great idea, but you missed a step ;-) I've replaced all of
our T8-T12'w with 1 to 4 std screw-in lamp bases (aka
incandescent) then just used cfl's. Total cost less than a
single replacement circline bulb. Easy to change, all the
advantages of cfl's, can adjust wattage as needed, and we're
ready for LED lamps in the future. Now adding a pull chain
switch for Hi/Lo. Need to look for a 4 wire pull chain,
off(optional)-1lamp-2lamps-3lamps ;-) Someone needs to make
a "three-way" Y adapter to hold two cfls, think of the
-larry / dallas
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