Fluorescent light ballast

Old 06-28-19, 03:45 PM
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Fluorescent light ballast

I changed several light ballasts today and I had an interesting experience with one. I have been doing ballast replacements since 1968 but this is one which I had never seen. The fixture was a double fixture with two sets of (2) 4' tubes on each side. They were connected and both fixtures were powered by the same ballast. After I changed the ballast I put new tubes in and all worked except one tube on the one fixture. So I put the lit tube into the opposite side of the fixture where the other tube wasn't lit, thinking that maybe the unlit tube was bad and to make sure that side was working. The good tube lit up so I put the bad tube in the other side where the previous lit tube was. It did not light up so that was easy- the tube was no good. So I tried a new tube after that one and another after that didn't light. So maybe all three tubes were bad and I went to another fixture in another room to replace yet another ballast. After I had replaced the ballast I tried the tubes that didn't light from the previous fixture and they worked! I thought to myself, wait a minute, now those tubes work but they didn't previously. All the wiring was right in the first fixture but for whatever reason I couldn't get that one side to work except when I used that one tube. I never had that happen to me before and I am puzzled.
Old 06-28-19, 03:56 PM
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You'll get a lot of similar feedback, you should ditch the fluorescent bulbs and ballast and make the easy switch over to LED, trust me you will never, ever, regret!

I changed over all the HO bulbs earlier this year in my garage, absolutely amazing the improvement!

Fluorescents bulbs are so 2010!
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Old 06-30-19, 07:07 PM
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I'd make sure the sockets and their contacts are undamaged in the first fixture, and that the lead wires are snug. If the sockets are unshunted, make sure both lead wires are secure. Of course, if they're shunted, there will only be one wire to each lamp holder. Sometimes lamps may start erratically if both pins aren't making a good connection. Also, confirm that the fixtures themselves are grounded. Fluorescent lamps not placed adjacent to a grounded metal surface are actually more difficult to ignite.

It's also possible that there's nothing wrong and the lamps are merely being stubborn. That's not unheard of with brand new lamps. The mercury may have condensed, and there might be some impurities in the gas fill. Once the lamps have warmed up, the mercury will vaporize and impurities will typically be absorbed, reducing the voltage required for starting going forward. Modern lamps don't contain excess mercury like they did in the past, so these kind of issues have become more prevalent. It sounds like you have parallel, probably electronic ballasts, which are better at lighting stubborn lamps than older series magnetic ballasts, but nevertheless, that might be all it is.

Not too long ago I had one brand new 15W (18") lamp the refused to light on an older trigger start magnetic ballast. All it'd do is glow faintly from the ends. I popped it into and undercabinet fixture with an electronic ballast and it lit up without delay, thought it remained a bit dim for the first few minutes. I ran if for about a half hour, then moved it back to the fixture that needed it. This time it fired right up, and is still working perfectly several years later.

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