I've got 48" x 4 bulbs F12 40W flourescent tube fixtures installed in my garage and in a downstairs family room. Most were installed around 1994. Some were new, some were older than 1994. They all have the older magnetic type ballasts. Over the last few years, they don't always start when the weather gets cold. Specs say that minumun operating temperature is 50F. The temperature in the rooms where they are installed is 66F, but they still won't start, or maybe one or two bulbs in a 4-light fixture will start, but that's all. I suspect that the ballasts have just gotten older and can't light the bulbs.
How does this happen? Why do magnetic ballasts loose their ability to provide power over time?
I've looked for equivalent electronic ballasts, but can't find any. I'm hoping that these replacement magnetic ballasts will work like the original ones. Specs say they are replacements for the originals.
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I'm assuming that the originals are failing because of age, because the ambient operating temperature (66F) is well above the minimum operating temperature (50F), therefore the ambient temperature has nothing to do with their failure. They are just old, and no longer operate within specs.
So, any opinions? And why do magnetic ballasts fail at low temperatures, and with age?
What Bob says. Go with LEDs You can get different colors these days if that bright white thing bothers you. I have a mix here. On the fairly nice fixtures I get the direct wire lamps and jumper out the ballast. On the plug in shop lights I replace the whole thing with a LED fixture. I bought a bunch at Costco on sale and as the shop lights get flaky, I chuck them. I still have a bunch of new F40 tubes that I would like to donate but nobody really wants them.
Are they well grounded? Are the tubes and reflectors clean? What is the humidity? I'd be pulling the tubes and installing direct drop in LED tubes - they will fire at -40. - and in 90+% relative humidity at 50F.
I agree , I went to LED's in my shop a couple of years ago , more light for way less electrical usage . And I got mine on ebay IIRC for around 5 bucks/tube . If you have a choice get the ones with frosted covers , I got the clear and they can glare .
Yup. LED is the only way to go. They come on right away no matter how cold my shed is. Inside the house I discarded the old ballasts and direct wired new LED tubes. In the shed I have a mix of the cheap shop lights and the drop in tubes for the one fixture that was still good. I have one T12 fixture left and I'll go to LED next time a tube burns out or dims.
Ever had a magnetic ballast fire? They usually don't burn the house down, although I suppose they could, but they sure fill the area with stinky smoke.
There is a lot going on. Depending on the design the cathode is first heated. That's what the two pins are for. If that circuit is bad or the filament in the tube is burned out, they will have trouble starting when cold. When warmer, the voltage from end to end is sufficient to fire the tube.
I have found generally speaking the direct fit bulbs work every bit as well as the ones that require removal of the ballast and they are one heck of a lot simpler to install. They are also fully certified and do not involve techically illegal modifications to the fixture where you apply 120 volts to a socket that is designed and certified for less than 40 volts (the cathode fillament voltage across a non-shorted keystone terminal set)
The direct fit is good for the home owner that does not know how to work with wiring.
For those that do know wiring they might as well use tubes that do not require the ballast. After all, the ballast could be the bad part.
While the fillament voltage may be low , the voltage across the gas tube is still very high or the tube would not fire off. Depending on the ballast it may range from 300 to 500 volts before the tube fires off.
That is pretty much what U/L does for you. Stuff might burn up but they certify the fire will be contained in the enclosure if it is installed properly. Note most "shop lights" say "hang it from a chain". That is so the heat from the can won't be transferred to a possible combustible surface when the ballast burns up. Better ballasts have a fuse link in them tho. No name chinese ones? Who knows? The U/L sticker is usually counterfeit if it is there at all.
Boris snipped-for-privacy@nospam.invalid wrote in news:XnsADDEBFF574DE4nospamnospaminvalid@144.76.35.252:
Wow. Thanks for all the replies. I had to do some research and reading to understand all the responses and possibilities presented.
I did discover something 'weird' about the condition of the flourescent fixtures and the ballasts/flourescent tubes. The fixtures have four F40T12 tubes, with two magnetic ballasts, one to operate each tube. I haven't discerned which ballast operates which two tubes, yet.
If I remove the two inner tubes, and turn on the wall light switch, the outer tubes will go on like normal. If I then install the inner two tubes, and sort of jiggle them around, they will both go on. Now all four tubes are light.
There are two of these four tube fixtures in this family room, each operated by a wall light switch. If I try the same thing in the other four tube fixture as in the above paragraph, the same thing happens. That is, all four tubes light up just fine.
If I turn the light switch(es) off, I have to repeat the procedure to get all four tubes in any fixture to light up again.
I installed the fixtures and wall switches in 1994, so I suspect that the ballasts are dying, and not that there are bad tubes.
Which means that it's useless to purchase and install Type A LED (Plug and Play) tubes (external ballast driven), even if I can find ones that are compatible with the (existing, and failing) ballast.
That brings me to Type B LED (Ballast Bypass/Direct Wire) tubes, that have an integrated driver (what used to be the ballast) in the tube itself. I must re-wire to provide voltage directly to lamp sockets. I find that bulbs are available in Single End Power, Double End Power (shunted across pins), and Universal Single and Double End Power. It looks like my sockets are configured for Double End Power, but I haven't physically examined them. It looks like this from the diagram on the ballast. Can someone tell me if this looks right? Here's the diagram again:
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Another choice is Type C LED, for which one must install an external driver in the fixture, and match the proper LED tube to it. Basically, it's like what I have now, a flourescent tube with an external magnetic ballast, but this is an LED tube, with an external LED driver.
And yet another choice it to replace the magnetic ballasts with replacement magnetic ballasts. I still have lots of F40T12 flourescent tubes, and temperature in the family room never gets below 60F. I think the ballasts are just too old. And, there are three other similar magnetic ballast fixtures in the garage, which also never gets below 60F, yet they have all of a sudden sometimes won't light. It's ever since the temperatures became more 'fall' like here.
Well, one more choice is to take down the old fixtures and install LED fixtures.
I think I'm ready to make a decision. It's between replacing old ballasts with same type ballasts, because I'm not worried about temperatures going below 60F (spec. says lowest temperature to function is 50F), and I have lots of F40T12s, and I know and like the lumens and color temperature that I have now, or direct wiring double ended tubes.
The jiggling part makes me think the pins aren't making a good contact with the strips in the tombstone (socket). The voltage across the pins is low, 40 or 50 volts iirc, and is used to heat the cathode. The end to end voltage is more like 500v open circuit and drops to 80 or so when the tube is conducting. The cathode heater usually isn't necessary until the temperature drops.
There are several schemes to handle the starting cycle.
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Back in the '70s the company I worked for subcontracted to GTE Sylvania to make energy saving fluorescent tubes. The tubes were about 5" shorter than the standard 4' and had a module glued on the end. The basic 'energy savings' consisted of a capacitor in series to limit the current. The assembly was complicated by a small isolation transformer to provide current to the heaters. The tubes would function fine with only the capacitor at room temperature but the heaters were necessary in warehouses or other unheated areas.
The "pin to pin" connections are NOT rated for 120 volts. Pin to ground is NOT the issue. You do will do what you will do. A lot of people are doing it but there is no approval for it, it is not within the design spec, and I will never recommend it as a solution, and no-one else should either.
Not only that, but if you have an instant start ballast you con't use the connectors anyway - at least on one end, because they are "shorted: keystones. Some only have the shorted keystone on one end (generally mag ballast) anf many electronic ballasts havce shorted on both ends.
The RIGHT way is to replace the fixture with a dedicated LED fixture (which I did on a few) but the "universal direct fit" tubes are functioning fine on 3 of mine (2 single and one twin tube) as well as
6 at the church and 14 or 15 at one of the insurance offices I used to look after. ( mostly 4 lamp dual ballast fixtures)
10 minute conversion including getting the ladder out.
I have never seen the actual listing document for the tombstones but here is an interesting take on it
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****************** Does installing a direct wire/line voltage LED tube void the UL rating of your fixture?
The short answer is no, but there's an important caveat. In order to maintain UL listing on your original fixture, you must place a modification sticker on the inside of the fixture, which lets electrical inspectors know that the fixture has been altered to bypass the ballast and directly transfer voltage to its sockets.
The following additional clarification was given by one of our manufacturer partners, Maxlite, at a seminar regarding this topic:
Basically, the UL certification is now transferred to the LED tube/retrofit kit, which is covered under UL standard 1598c. Installers should follow all instructions and the fixture must be clearly labeled to warn users against re-installation of fluorescent lamps.
Most reputable LED tube manufacturers these days include relamping stickers with the purchase of their products, making it easier for installation crews to properly modify fixtures.
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Since UL does list the kit, I would say the sockets must be up to the task.
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