How to disconnect fluorescent lights?

[Walter R.]

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)?

Thank you

[PipeDown]

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.

[Edwin Pawlowski]

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.

[Joseph Meehan]

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.

[ameijers]

Lordy, y'all make things hard. In the egg cartons at work, when people find 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.

aem sends...

[Joseph Meehan]

That works, but I am not sure it address the issues at hand.

[Pop]

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) current.

[Joe Fabeitz]

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 removed.

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?

[Sawney Beane]

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 >

[Stretch]

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!!!

Stretch

[Sawney Beane]

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 break>

[Pop]

Sheesh is right.