What specs do I have to match to replace a ballast? The fixture (about 10 years old) burns out lights soon after replacement, and an electrician said it was a bad fixture. He didn’t seem too sharp, and didn’t seem to do any diagnostics on it, just told me it was “bad.” It seems to me that the only thing wrong could be the ballast.
It’s a decorative fixture, not one of those utility fixtures that you pick up at Home Depot, so I would like to salvage it if possible. The ballast has the specs on it. I looked it up and that particular model is out of production but I would think that any ballast that is spec’ed for the same output could replace it.
Logically, the replacement ballast should have about the same inductance, and be able to withstand some average current through its wires and maximum voltage across its wires. Therefore you want about the same number of henrys or millihenrys and at least the same amps and volts. So I think we’d be safe in assuming that these items aren’t the specs they list.
What do you mean, “the same output”? What things are measured and in what units?
It gives the line current for various loads in watts, assuming 120v/60Hz. See this photo. It’s fairly hi-res so maximize your browser window and with IE click on the “expand” icon to see it full size.
(Interestingly the label says that one of the certifications does not include using with 34W U-tubes, but that’s exactly what the fixture is built for and came with.)
Is that enough information to match a replacement?
My first instinct, born of experience, was to say, with a weary sigh, “Replacing the ballast can cost more than just buying a new fixture”, but I thought it’d go better with a cite, so I went and found one. Bottom line: unless it’s an unusual or custom-made fixture, or you just really, really like it, it’s sometimes cheaper to just buy a new one. Sad but true, we live in a throwaway society. So throw it away.
But if ya don’t wanna, the linkie has a bunch of information on replacing ballasts, too. And there’s a bunch more stuff here, and here is a brain-exploding amount of hard-core techie stuff on fluorescents and their ballasts–enjoy!
What you’ve got there is a very standard dual 40 watt bulb magnetic ballast. They are very easy to replace with a newer, more efficient, electronic ballast. They are lower weight, use less energy, generate far less heat and are even available in dimmable models (but those are fairly $$$).
Two points -
1.) Are you replacing both lamps at once? Replacing only one of a pair is guaranteed to cause very short bulb life.
2.) 10 years ago as a building engineer, the most expensive fluorescent bulbs in the building were the U-tubes. They were 4-5 times the cost of any standard size fluorescent. Take that into account when deciding if the cost of a new ballast outweighs the cost of a new fixture
These prices are probably comparable to or a bit higher than a big box hardware store. I recommend the electronic, if replacing the ballast is the route you choose.
If there’s one thing I’ve learned in my years of being lazy it’s that a bad ballast (if it lights a bulb at all) will burn out bulbs very fast. Any time I replace a tube and it burns out within a day, the ballast get’s replaced next. Really, other then shoddy wiring, there’s not much more that can go wrong. On the flip side, leaving a bad bulb in the socket to long seems to shorten the life of the ballast.
Oh I guess there’s two things. Remember when you drop that ballast, if it’s been on for a while it’ll be heavy…and hot.
