I have an "U" shaped fluorescent light in my kitchen that may or may not come on at the first flip of the switch. If you rapidly flip the switch several times, then it will come on and stay on. It is the only light on the circuit. I hadn't changed a thing on the circuit, so it shouldn't be something I did. We changed the bulb and changed the switch but it still did the same thing. I have another fluorescent light exactly the same next to it (two lights in the kitchen) and it works fine. Would the ballast be bad?
Certainly the ballast can be bad. Be sure the pins of the FB tubes are snapped into the sockets. Sometimes they don't make it all the way in. If you replace the ballast, get an electronic retrofit ballast, as opposed to the standard magnetic ballast. They make them now for T12 lamps as well as T8, and they work so much more reliably
Thanks for your answer. Where can I purchase the electronic ballast and what numbers do I look for in the replacement. I will take the old ballast with me when I go, but I'm sure I won't find a guide that will tell me a replacement ballast for the one I have.
For a replacement ballast, look on the label of the ballast that's in your fixture now. You will see the types of lamps that will work with that ballast. If you don't see your U-shaped lamp, that's O.K. Probably the U-Lamp is electrically like an F40T12/RS or some other type for which there is a linear equivalent. Then go to the store and buy a ballast that operates the same types of lamps.
There are several things that could be affecting the starting of your U-Lamp. Fortunately, they are all fairly simple to check.
- First, take out the lamp and clean it carefully with Windex or dish detergent. Rinse and dry thoroughly. (When a film of dirt builds up on the surface of these lamps, they become a bit harder to start.)
- Second, take the lamp out of the socket and then replace it again so the pins scrape the socket contacts.
- Third, check the metal part of the fixture to be sure it's grounded. The ground (bare or green) wire of the incoming cable should be connected to the metal of the fixture and/or the metal case of the ballast. You can also check grounding with an ohm meter.
- Fourth, check to see whether the "hot": and "neutral" wire are reversed. This is unlikely since the lamp has been O.K.; but the lamp will have trouble starting if those wires are reversed. The black wire of the incoming cable should go to the black wire of the ballast and the white wire should go to the white wire of the ballast.
The basic problem is that older ballasts are designed to provide just enough voltage to start the lamp and very little more. And, a grounded fixture is part of the starting circuit since a grounded metal strip must be within
3/4 in. of the lamp. So, as the lamp ages and the starting voltage requirement goes up, poor grounding, reversed leads, dirty lamp may all conspire to make the lamp harder to start.
When you flip the switch, you are forcing the ballast to hit the lamp with a pulse of voltage. When you hit the switch just at the right point in the 60 Hz cycle, enough voltage is generated to start the lamp; but that may take several tries as you have found.
If you decide to change the ballast, go with an electronic type. They put out plenty of starting voltage.
Thanks to all who answered. I replaced the old ballast with a new one purchased at a national builders chain and it worked. Replacing it was a lot easier than I thought it would be. The only problem I had was that the new wires were too short so I cut the wires (and ends) from the old ballast and put them on the new ballast with wire nuts. They didn't have new ends so I was going to have to use the old ones anyways. This actually worked better because the store geek told me I had to pull the old wires off of the ends and plug in the new wires. That kinda bothered me. It didn't seem to me that doing it like that would make for a dependable connection in the future. Thanks again.
I recently found 4 standard fluroscent fixtures buried above a drop cieling that were ungrounded from when they were originally installed
20 or 30 years ago by a previous owner.......
I was helping a friend with her elderly moms lights.
The #@$% original installer cut the ground wire off the romex. I guess the wiring is safe based on the test of time, its not properly installed, fans out of boxes that are way too small. The drop cieling must of been installed after the lights were put up, they hang by chains. access is horrible, the lights hard wired. although no anchors were used at fixtures either
I replaced all the bulbs, and did some minor repairs which took forever because of poor access.
I am not happy with the wiring but fear I could start a big house rewiring job and the ladies kids at least one replaced a ballast years ago so they must know its a mess......
I am looking for opinions, fixtures start OK but are a definite shock hazard, but I really dont want to rewire a house.
The lady is elderly, when this house goes up for sale home inspectors will have a field day. nice home porely maintained.by people who had no idea how to do it right
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