My kitchen ceiling has 4 light fixtures with 2 fluorescent lights in each of
them (T-12 4' long). This is too bright and wastes energy.
I would like to deactivate 2 of the fixtures. Can I just pull the 2 tubes
out of 2 fixtures, but leave these fixtures (with the ballast) connected to
the house wiring?
Would this damage the ballast? Would the fixtures, with the ballast but
without the tubes, still draw power? Or, should I disconnect the wires to
the fixtures (more trouble because I have to open the fixtures)?
As long as you take both bulbs off the same ballast it should be OK as long
as nobody sticks a finger in the unoccupied fixture. Put up a little
electrical tape to CYA.
Sounds like you already know how to disconnect, why not go all the way and
install a pull string switch on the side so you can turn on/off the second
lamp at will. You get the best of both worlds and its not that hard. I
assume there will be sometime when you want a lot of light.
If you are heating your house, you are not wasting energy. The energy used
to light the bulbs and turns into heat and therefore your main heater works
less. In the summer, the AC will work harder though.
I'm told that just removing the bulbs does little to the current draw and
the ballast is still using the electricity. Someone more knowledgeable than
I would be better suited to answer that.
If the fixture is too bright, you may want to consider replacing it. IMO,
fluorescent light is too harsh for a kitchen. Or course, that can cost
thousand of dollars. If you removed the fixture, the ceiling will have to
be painted. That means the walls have to be painted or papered as they will
look dingy. Once that is done, the floor is going to look old so you'll
have to get that ceramic tile you always wanted. You get the idea, the new
fixture can run up to $10,000 or more.
I could be wrong, there are many kinds of ballast, but I believe that
must if not all will draw some current anytime the power is on, with or
without lamps. They will just warm up. However I believe the total
energy consumed is less and as far as I know the ballast will not be
damaged. Personally I would re-wire it so I could turn on one or both.
There are several ways of doing this. You also could disconnect the power
to one ballast.
the lights too bright, they just reach up and rotate the bulbs a quarter
turn. They don't fall out. Now these are commercial fixtures, not sure if
residential flourescents hold the tubes as well.
No problem removing two bulbs; won't hurth anything and the open
part of the ckt where the bulbs were will still draw some
current, but a negligible amount. A ballast is a transformer so
an open secondary will cause very small primary (ac-house)
: My kitchen ceiling has 4 light fixtures with 2 fluorescent
lights in each of
: them (T-12 4' long). This is too bright and wastes energy.
: I would like to deactivate 2 of the fixtures. Can I just pull
the 2 tubes
: out of 2 fixtures, but leave these fixtures (with the ballast)
: the house wiring?
: Would this damage the ballast? Would the fixtures, with the
: without the tubes, still draw power? Or, should I disconnect
the wires to
: the fixtures (more trouble because I have to open the
: Thank you
Removing both bulbs on a ballast will cause that circuit to draw ZERO
current. The traditional ballast places an inductive resistance in series
with each tube to limit the current when the tube is illluminated. Removing
the tubes breaks the series circuit. The newer electronic ballasts will
draw a small amount of current (less that 1/10 amp) even with the tubes
BTW, why do you some of you guys feel compelled to respond to these
questions even when you don't know the answer? You typically begin your
post with "...I don't know much about this but....." Why not shut up and
learn from others?
With no tubes, the inputs of a magnetic dual F40 ballast
should show 13 ohms. Thanks to inductance, the ballast
without tubes should draw only 1/3 amp at 120 VAC.
That sounds like 40 watts, but in fact the power should be
negligible because with no load on the transformer, current
should lag voltage by almost 90 degrees. In the past I have
been curious enough about such things to shut off everything
in the house except some incandescent bulbs, time the wheel on
the service-entrance meter to see how many rpms per kilowatt,
then time the wheel to measure the power consumption of a device.
(If somebody could tell me how to read the specs on a power
meter and determine how fast the wheel should turn per watt, I
wouldn't have to play with light bulbs.)
I like the idea of installing a switch. If I were going to
use four tubes, I'd use two fixtures. I'd get the kind that
throw light to the sides and paint my walls a light shade.
That way I could have plenty of light without its seeming harsh.
Joe Fabeitz wrote:
When you remove both of the 4' or 8' tubes on one ballast, it opens the
circuit of the power going to the ballast. Check the fixture ends
(bulb holders) and you will see what I mean. Therefore there is no
power applied to the ballast and it uses ZERO electricity. SHEESH!!!
I once had a fixure light that in my kitchen. It was
instant-start. The tubes had one pin on each end. They
started with cold cathodes, which required a lot of voltage.
Because of that voltage, each pin was a sort of interlock to
break the primary circuit if the bulb was removed.
Rapid-start and preheat tubes pretty well replaced them
because they were would stand a lot more start cycles. I've
never seen a schematic for a magnetic rapid-start two-tube
ballast where removing tubes broke the primary circuit.
I just checked my kitchen light. Without tube 2, both ends of
tube 1 glow. Without tube 1, tube 2 will light up. So either
tube can be removed without breaking the primary circuit.
With no tubes, I read 11.2 ohms between hot and neutral. The
primary circuit is not open.
: When you remove both of the 4' or 8' tubes on one ballast, it
: circuit of the power going to the ballast. Check the fixture
: (bulb holders) and you will see what I mean. Therefore there
: power applied to the ballast and it uses ZERO electricity.
Educated guessing again, eh? You need more education. The BULB
ckt has zero current, but the BALLAST primary is still pulling a
small current. It's not ZERO! Removing a buld does NOT open the
primary side of the ckt.
Sheesh is right.
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