A bank of flourescent lighting in the kitchen went out a few day ago,
but this morning when i turned on the light switch, they came back on.
Would these bulbs be bad or could it be a starter or ballast causing
this? There are four lights separated in one fixture, two lights to
each holder. The other lights are okay. Thanks.
How many ballasts are there? Are there any starters?
What length and diameter are the bulbs? Sometimes this gives an easy
clue that can largely rule out presence of starters. Sometimes this
indicates that you are less likely to have only one ballast.
When the fixture works, in what manner do the bulbs start? Truly
instantly? Instantly, although with a slight "bump" in brightness during
the first second operation? Delay of up to 1 second and then WHAM they
are on? Dim and maybe slightly flickery during the first second or so?
Blinking randomly for a second or two? This can most of the way confirm
or deny the existence of starters and may largely disprove all 4 bulbs
running on only one ballast. That can save work opening up the fixture to
If there is more than one ballast, it is extremely unlikely that they
all conked out simultaneously and then recovered. A much more likely
explanation is a bad connection somewhere. If a switch controls the
offending fixture and other fixtures simultaneously, then the problem is
possibly anywhere from the switch to the fixture, but with usual switches
and more common wiring methods the problem will not be the switch and will
usually be in or near the fixture.
Possible alternative explanations:
1. The fixture is not properly grounded. Fluorescent fixtures require
proper grounding and the bulbs to be within 1/2 inch of grounded metal
screen or grounded sheet metal for reliable starting. This affects the
voltage gradient within a bulb that is attempting to start.
Keep in mind that fixtures not properly grounded have been known to
start, but the reliability of starting is lower.
1a. Hot-neutral reverse can have a similar effect.
2. The bulbs have a film of dust that is hygroscopic and slightly
conductive when the humidity is higher. That can also screw up the
voltage gradient within bulbs that are trying to start. This happens more
in coastal areas. The fix is to wipe the bulbs clean.
3. If the bulbs normally blink randomly during starting, then you have
"glow switch" (usual kind) starters. Sometimes those have trouble
starting in complete darkness and are assisted by the photoelectric
effect. If your fixture has starters and it fails to start and start
failure is in darkness, try shining a flashlight at the fixture to see if
that kicks the fixture into starting.
If this turns out to be the case, replace the starters with ones of a
different brand but same basic type (usually FS-2 or FS-4).
Other partial fixes that *may* work somewhat in this situation are:
a) Have some glow-in-the-dark material in the fixture. (No, I have not
actually tried this.)
b) Have a mass of a potassium compound as close to the starters or at
least one of them as possible. If you can find that reduced sodium table
salt that is half potassium chloride, that may work. Potassium is
slightly radioactive. It may take a while for a radiation particle to
both hit a starter and kick a starter into functioning. (No, I have not
actually tried this.)
4. If you have only one ballast, it may be the ballast - but my
impression is that most ballasts that run 4 bulbs are electronic ones, and
most of those work as they did before until the second they die and after
that they are usually permanently as dead as a doorknob.
Of course, some 4-bulb electronic ballasts have marginal design, but the
usual main problem with marginal design is not all bulbs starting (when
the ballast runs many bulbs) or the bulbs are dim or the bulbs have short
life or the ballast dies (permanently) too easily.
Some fixtures do not work in extreme heat, but the usual symptom is that
they turn on and off every several minutes. Those fixtures have "Class
P" thermally protected ballasts.
If you have one doing that thermal cycling thing, that needs to be
fixed. My concern is that the thermal protection device might wear out
and then the ballast could catch fire. The ballast may have a minor short
and need to be replaced. Some cheap fixtures, especially many "shop
lights", have cheap garbage ballasts that require the region of the
fixture having the ballast to have air around it rather than being mounted
flush against a ceiling or beam. That is the reason for some of those
shop light fixtures to have chains to suspend them with.
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