Changing Ballast in T-12 Fixture ?


Old 01-31-10, 09:31 AM
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Question Changing Ballast in T-12 Fixture ?

I have three 35 year old recessed 2 lamp T-12 fixtures that I suspect need new ballasts. I am using T-12 40 watt bulbs. Recently when the lamps are on for more than 8 hours straight there is an electrical component smell coming from the fixture, but I have not looked at the ballasts yet. What other signs of failure does a ballast show besides leakage, smell and starting problems. There are no other problems with the fixture or lighting other than the smell over long periods.

If I replace the ballast which type/brand should I go with. Since this an old fixture it probably has a magnetic ballast, should I consider a an electronic? Is there a ballast that can work with the T-12 and a lower wattage T-8? Lastly, which of the common brands available are most reliable such as Philips or GE (the current fixtures have GE).
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Old 01-31-10, 06:10 PM
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It is highly possible you can replace the entire fixture cheaper than you can buy a ballast. I would check into that first before I tried to change the structure of the lamp itself by buying components. The age tells me the ballast needs replacing, and over time the tombstones will wear out their contacts, so you are left with a piece of sheet metal and no guts.
Old 02-01-10, 07:46 AM
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I'm not sure about other stores but I know the Home Depot around me carries electronic ballasts that are made for T12 fixtures. They run about $15. I will check to see a brand name.

Edit: The brand is GE. They are electronic and replace T12 magnetic ballasts. They also state on the package that they save 15% energy compared to magnetic ballasts. Here is a link:

Last edited by Tolyn Ironhand; 02-01-10 at 09:44 AM. Reason: added info
Old 02-01-10, 01:11 PM
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Thanks for the link Tolyn! The 15% energy savings and $ 15 for the electronic sounds good. Would a there be any disadvantage for the electronic ballast compared to the magnetic iron core type, for instance more radio interference or reliability? I think I read that magnetic ballasts will be discontinued due to gov energy savings requirements. So the magnetic choice may not matter any more, but I thought I would put it out there.

I found what look like a magnetic (does not say electronic -) Philip brand ballast at Lowes. Not sure about the Philips reliability though.
Old 02-03-10, 03:37 PM
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You should really get a new 2 lamp t8 fixture. but if your adament about getting a new ballast, given its in your house, you will need a 120v 2lamp T8 electronic ballast and it will have the wiring diagram on the ballast itself. Obviously get two T8 lamps to replace whats there, seeing that the new ballast will be calling for T8's
Old 02-13-10, 09:20 PM
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Considering the fixtures are recessed, they may not be easy to replace. I think I'd advise an electronic ballast for T8 lamps and new lampholders too. 35 year old lampholders are a problem waiting to happen. I'd use either an Advance or Magnetec/Universal ballast. T12 lamps won't be available a lot longer.

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