[billcerts]

Hello everyone,

I have 10 lay-in four tube fluorescent fixtures in my shop, with a total of 20 two bulb ballasts. Three of the bulb pairs were flickering, so did the standard resistance test:

Neutral white wire to each hot out, red, blue and yellow. All three were showing around 10 ohms on the blue wires, red and yellow were fine. Not liking coincidence, I checked all 20 fixtures, and all are showing 10 to 12 ohms on the blue wires even though all of the other fixturs are working just fine. What am I missing? Thanks in advance for any thoughts.

 

[rjniles]

In my experience, resistance tests on ballast prove little. Swap some known good or new lamps into the problem locations. If they flicker, replace the ballast. Or convert the fixture to LED (my first choice).

 

[billcerts]

Thanks for the input. I tried putting new bulbs in and they work for a few days, then the ends get black and they start flickering. Maybe the high start voltage is leaking after startup?

 

[seharper]

I have 10 lay-in four tube fluorescent fixtures in my shop, with a total of 20 two bulb ballasts. Three of the bulb pairs were flickering, so did the standard resistance test:

Neutral white wire to each hot out, red, blue and yellow. All three were showing around 10 ohms on the blue wires, red and yellow were fine. Not liking coincidence, I checked all 20 fixtures, and all are showing 10 to 12 ohms on the blue wires even though all of the other fixturs are working just fine. What am I missing? Thanks in advance for any thoughts.

That test doesn’t mean a lot on ballasts. The diagnosis is super simple: swap in a known-good pair of bulbs; if still flickering, the ballast is defective, and swap the ballast.

I tried putting new bulbs in and they work for a few days, then the ends get black and they start flickering. Maybe the high start voltage is leaking after startup?

Destroying tubes is a classic failure symptom of an obsolete magnetic ballast. (The ones that buzz, and are quite bulky, and start hard in the cold, and cause 60Hz flicker, even on a good day).

Do not hesitate to swap them out for electronic ballasts. You want the rapid-start or programmed-start variety, since those are directly compatible with your 2-yellow 2-blue 2-red wiring. Avoid “instant-start” as they are confusing to wire.

Combine that with modern 90 CRI tubes (best light on the market) and you won’t even believe they are fluorescent lol. They will serve you well for decades.

This is the time for a technology shift. Your upgrade path is 1 of 3 ways:

T-12 tubes, electronic ballast: All the benefits of modern fluorescent and you keep your old tube type, so your old stock of tubes will keep working. However the newer tubes are really nice, so research the “CRI” on your existing stock of tubes. If it’s less than 90, maybe it’s time to get 90 CRI.

T-8 tubes, electronic ballast: These are more efficient than T12 tubes, so you’ll save energy for the same light. They snap right into the same sockets. But they are not electrically compatible; T8 tubes on T12 ballast (or vice versa) is no-go. This is what I am doing at our facility, which has about 150 ballasts.

It’s six of one, half-dozen of the other to go T8 vs T12, but supposedly T8 tubes will continue to be available and T12s will be deprecated. I don’t see that happening for a long time.

LED Conversion, plug-n-play: They now make LED lights in the shape of a T-8 tube, which will snap right into your fixture. The plug-n-play variety require you to maintain a working ballast (T8 or T12 they don’t care). This also means you can rollback to real fluorescent once you find out how hokey these things are. Or LED conversion, direct-wire In this case, you remove/bypass the ballast, and shoot 120V straight into the fluorescent socket. So you’re all-in on LED at that point.

I personally find that both kinds of LED have serious quality problems, largely because the business is such a “gold rush” and you have lots of cheap bottom-feeder overseas builders dumping sheer volumes of junk onto the market. It’s not price competitive; real modern fluorescent ballast+tube upgrades are same or cheaper. And you’re getting GE/Philips ballasts and Sylvania/Philips tubes, which will probably outlive you in a home shop setting lol.

By the way, you can get 4-lamp ballasts now... though most are “instant-start” with a bit different wiring. 4-lamp rapid-start ballasts can be found. The advantage to rapid-start is it’s much easier on the tubes, so longer tube life.

Electronic Ballasts have a figure called “Ballast Factor”. 1.00 is normal brightness. One guy on eBay has programmed-start (excellent) ballasts for $5, but those are 0.71 ballast factor, so pretty dim. If it wasn’t for that, I’d have bought 50 of em for my own conversions!

 

[Jim Port]

T12 lamps are obsolete and are being phased out. Don't go wasting money on them when better options exist. You will also spend more for ballasts and lamps vs switching to LED.

 

[djhutt]

When the ends of a fluorescent tube blacken with a magnetic ballast it is a sign of the low voltage for the filament is non existant

 

[seharper]

T12 lamps are obsolete and are being phased out. Don't go wasting money on them when better options exist. You will also spend more for ballasts and lamps vs switching to LED.

Oh, that’s not even slightly true. Real fluorescent is cheaper *and* higher quality by far. Why do you think I do so many of them? LOL

Mind you I’m really good at bargain hunting and I do my T8 conversions for about half what LED conversions would cost. (Assuming we’re making some effort to not be an idiot, and y’know, buying a halfway competent LED instead of the cheapest thing that falls off a truck in Shenzhen).

I think if OP works with just run-of-the-mill ballasts.com, 1000bulbs or eBay, and makes a modest effort, he could change to T12 ballasts for $3-4 per tube cheaper than going LED.

Going T8 would be a wash or a buck or two cheaper than LED depending on bargain finding skills. (The sweet deals I got are largely gone).

Bargain-hunting on eBay for fluorescent ballasts is pretty safe, since the junker gang isn’t counterfeiting those.

 

[Jim Port]

Oh, that’s not even slightly true. Real fluorescent is cheaper *and* higher quality by far. Why do you think I do so many of them? LOL

.

Funny, this title says otherwise

The phase out of T12s: Everything you need to know about discontinued tubes

This is a two-part answer.

First, back in 1992, the government amended the Energy Policy and Conservation Act to require a careful review of energy standards. The Department of Energy is expected to publish new standards as more energy efficient technologies make their way to market.

As a result, in 2009, the department announced the eventual phase out of the 1.5-inch-diameter fluorescent T12 tubes. The mandate said production of the tubes would have to cease after July 14, 2012. Big-name manufacturers like Philips and Sylvania were granted two-year extensions on the deadline. But as soon as the phase out was announced, production began to decline. It was a combination of the impending restrictions, increased energy efficiency awareness, and emerging rebate programs targeting those with traditional T12 fluorescent tubes.

Whole article at this link.

https://insights.regencylighting.co...ing-you-need-to-know-about-discontinued-tubes

 

[seharper]

Jim we’re crossing subjects. I was challenging the cost issue; I do a ton of it and it’s actually cheaper to update ballast and lamp to T8/modern tubes if you make any effort at all to shop smart.

That’s a “scare” article by an upgrade seller. It’s the lighting equivalent of the “OMG Pushmatic very scary” articles on electrician sites.

Sloppily written; a few statements are flat lies: “T12s need magnetic ballasts” no, they work great on electronic T12 ballasts. You get all the modern advantages, but not as much efficiency as you’d get from T8.

The government didn’t outlaw T12s *literally*, just like they didn’t outlaw incandescents *literally*. They outlawed them *in effect* by setting an “impossible” efficiency and CRI standard for T12s - like 80 minimum CRI, which (at the time) was a big deal.

This government meddling failed utterly. The industry easily met the new regs. Note that your local retailer is awash in new-build T12s with 90 CRI or better, for perfectly reasonable prices..

By the time the government realized they’d been “had” and started figuring out how to attack T12 next, the market came along and did it for ‘em. Most people are either going LED or T8 of our own volition.

There’s nothing more to do with T12 except wait it out. 10 years hence no-one will use them except a few hold-outs, and there aren’t enough of them to make a difference.

This is typical of government regs, particularly, environmental. They’re only interested in low-hanging fruit - easy problems to attack. That’s why house-paint and auto-paint got VOC’d to death, but marine paint was untouched. That’s why California leaves classic cars alone; they’re not driven enough to matter. I don’t expect any further government attacks on T12 at this point.