Actually, it’s not an emergency, but I do need some insight from an electrician if we have one.
I installed florescent lights in my basement. There are four lights with 2 bulbs in each. They are wired in a row. Lights 1, 3, and 4 work fine. Light number 2, does not. It blinks on for a second and goes out. I thought there was a short in the light, so took it back and exchanged it. The new one does the exact same thing. There has to be power getting to it because the two on the other side of it are working fine.
Any ideas on what might be going on and how I might fix it?
Does in a row mean parallel, series or some combination of the two?
If you called me in to diagnose this, the first thing is double check that you replaced the fixture. Next I would double check that you exchanged the bulbs as well. If the bulbs are the same as the ones from the first time, I’d swap them out with one of the good sets so that I now have ‘known good’ bulbs in the problem fixture (and we could seem them work in a different fixture). This would now mean our problem is in the wiring. I would then pull the bulbs out of the bad fixture and expose the wiring. With the lights on, I would check the connections for power. There should be voltage from black (or red) to ground and voltage from black (or red) to white. There should be nothing from white to ground.
I would also use a multimeter to make sure the voltage is somewhere in the 110-120v range.
Also, I would double check your wiring in all the other fixtures. You could have a bad connection somewhere else manifesting itself here. Check the neighboring fixtures and make sure the wires are well twisted, the nuts are on well and nothing is accidentally grounded or pinched when you put the covers back on.
Also, a nitpick. You said “There has to be power getting to it because the two on the other side of it are working fine” What I hope you meant is “There has to be power getting to it because it blinks on for a second.” The other lights getting juice doesn’t mean this one has to be getting any…that’s where our testing will begin. Is it getting power when it’s not working?
ETA, Now that I think about it, the first think I would do is test for a good ground before I put my hand on the metal fixture while it’s live. If you have a short to an ungrounded fixture, that could be doing something wonky with the ballast.
Thanks for the help. In a row means that the wiring goes from the switch to light one, then to the one that’s not working and then to three and four. I have triple checked the wiring on the non working light and changed the bulbs, but I haven’t rechecked the wiring on the other lights. I will go do that now. Thanks.
you need to know how and where to safely check voltages if you are going to do that. in a basement the floor/walls/ceiling (if made of concrete, concrete block or brick) are all good electrical grounds; you want to be isolated (not touching) from those with dry wood, rubber or fiberglass. things in a basement like light fixtures, water pipes, gas pipes, metallic electrical conduit, metallic ceiling supports are grounded and you don’t want to touch those while you are testing electrical wires.
when measuring touch only the insulated plastic probes of the tester or meter. don’t let the wires touch any other metal.
a fluorescent fixture needs to be grounded well for a bulb to give light.
Yes, IIRC from HS physics, there’s going to be a voltage drop across each fixture. In an incandescent setup, I think that would show up as each bulb in the series getting dimmer. I don’t know what happens when you apply to little voltage to a ballast though but it wouldn’t surprise me if the bulb didn’t light (or flickered or was dimmer, but I’ll bet the ballast still gets warm). Also, it’s odd that only light 2 isn’t working, but without seeing how it’s actually wired, I can’t say, perhaps light 2 is actually last in the chain. It’s probably moot anyways, as I suspect it’s actually wired in parallel as wiring in series means mis-matching wire colors.
Thanks guys. These are wired in parallel and the light in question is the second one in. I checked all the wiring and tightened a ground screw. Light still didn’t work. Then on a whim, I reversed two of the end caps which should not have made any difference, but it works now.
I’d guess the end cap wasn’t on tight enough and not making good contact with the pins, when you first turned it on it arced enough to light the bulb for a second…after you did it a bunch of times did it smell like a photocopier in your basement (ozone)?