I bought a fluorescent light fixture with 2 light bulbs. I wanted to test if the light bulbs where good before mounting the fixture to the ceiling. So I simply plugged the cable to a 120V outlet. I heard a spark and only half of one fluorescent light bulb is on.

Did I burn them by doing this? I thought there is no difference whether it is 120V from an outlet or a ceiling.

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    It sounds like this is a direct-wire fixture, so to test it from an outlet, did you install a plug first? – Steven Oct 11 '12 at 2:24
  • More detail on the wiring, please. Note that fluorescent tubes need a differential of several hundred volts to ignite and thus need some sort of "ballast" for starting them when connected to 120V house current. hypertextbook.com/facts/2003/KarryLai.shtml – Brian White Oct 11 '12 at 2:34
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    Are the tubes properly seated in their sockets. Most of the ones I deal with (T-12, T-8 Bipin) have to be given a quarter turn to properly seat them in the brass contancts. It's easy to either under-turn or over-turn and end up with one filament set not properly in contact with its socket connections. – Fiasco Labs Oct 11 '12 at 3:42
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    You're welcome! As single man IT department, head cook and bottle washer, I also get the janitorial jobs at work. I've heard that noise before (on electronic ballasts a sizzle) just before a freshly changed tube immediately goes out after flipping the switch back on. Having to climb ladders for no good reason causes you to develop a touch for feeling when those pins seat. – Fiasco Labs Oct 14 '12 at 0:50

You shouldn't have any issue. Alot of ballasts are rated 120v/240v. A regular wall outlet is usually 15a 120v. Which you should be fine. Is this a t8 t5 or t12 fluorescent light fixture. I mean it is possible that you have a bad ballast that is only providing the proper power to the socket for only the bulb that lit. Try taking the bulb that is lit out of that side and switch it to the side that isn't lit. That should give you a rough idea that something is wrong. Check the connections at the socket of the side that isn't lit make sure the wires are actually in the socket. But again test the other side with the good bulb. sounds like a bad ballast in my opinion. But again no...plugging it in shouldn't have hurt anything. Getting power that way isn't really any different than hard wiring it.

  • If T8s fit in the sockets you could simply replace the T12 ballast for an electronic T8 ballast. You’ll save on your Electrical bill. The T12 ballast should say something like No PCB on the label. If it doesn’t and you notice a leak replace the fixture and dispose of the old one in accordance with your local recycling laws. – Rob Nov 9 '20 at 21:54

You should get the same voltage from the outlet and ceiling. And almost every fixture comes with a ballast.

Did you do the wiring to the plug, or did it come with the fixture?

Ballast have specific ways to connect to electricity

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