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T12 Lighting Fixtures

02/25/2012 12:33 PM

I have 8-T12 fluorescent light fixtures (2 lamps per) in my shop. Sometimes when I turn on the lights for the first time of the day, all but 2 or 3 lamps will light. If I flick the switch a few times, they will all light and sometimes it won't help. Other times, I have no trouble; I flip the switch and they all light. The temperature doesn't vary to any great amount, but the humidity is on the high side. Temperature varies from the upper 40's to the upper 60's. The fixtures use regular ballasts.

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#1

Re: T12 lighting fixtures

02/25/2012 1:30 PM

Is it always the same 2 or 3?

You may want to try removing all of them, wipe them down with a paper towel and some rubbing alcohol, apply some dielectric, (bulb), grease to the contacts, and replace them, using a paper towel or gloves to keep your hands off them. Hit the switch, and if any don't come on right away...........make sure they are properly seated in the fixture by slightly turning them until they light.

If that doesn't do the trick, and you have room in your panel, try splitting them into two separate circuits with two switches. You may be pulling too much juice to get all of those ballasts fired up at once.

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#2
In reply to #1

Re: T12 lighting fixtures

02/25/2012 1:52 PM

I have them split up; 3 fixtures per switch. yes the same 2 or 3 lamps.

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#3
In reply to #2

Re: T12 lighting fixtures

02/25/2012 2:12 PM

Hmmm...........................I would say to go buy some new bulbs. But before you do that, try swapping those three out with three from the other fixtures that are working. At least you will be able to narrow down the problem to whether it's a bulb or fixture/ballast/starter problem.

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#4
In reply to #3

Re: T12 lighting fixtures

02/25/2012 7:03 PM

The tubes are not black at the ends. Today they turned on without any hesitation. I hesitate to change the lamps because they are 10' above the floor in a cluttered shop. Hard to set up a ladder, but I will have to do it sooner or later.

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#5
In reply to #4

Re: T12 lighting fixtures

02/25/2012 9:00 PM

I'd suspect the starters (which are very cheap & easy to change). Also think Kram's idea of swapping tubes around is a good idea.

You ain't going to fix it from ground level - think you'll have to bite the bullet & set up a good ladder (with some good assistants) - or better, a tower.

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#12
In reply to #4

Re: T12 lighting fixtures

02/26/2012 5:08 PM

Don't get mad at me, but I don't think you should climb a ladder to get those bulbs out. Maybe a kid that's willing to pick up a quick $20. Even at my youthful age of 50, I'm not feeling like a spring chicken anymore. I've got a buddy down in Atlanta, (56 years old), that thought propping up a ladder against his joists in his basement ceiling was no big deal. He slammed himself to the concrete floor so hard, it shattered his elbow. He's got a fake elbow now................but his arm doesn't work right, and it hurts every day.

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#6

Re: T12 Lighting Fixtures

02/25/2012 11:27 PM

I would say, new tubes, but it could be a bad ground on the fixtures. They need to be grounded for the lamps to work properly. Maybe you should look ahead to converting the fixtures to T8's or T5's. Soon the T12 tube will be going the way of the 100 W incandescent lamp, I think the middle of this year. You will have to change the ballast to an electronic one that uses less power and produces less heat to work with the new tubes, maybe ends too, to get the lamp closer to the frame of the fixture. The ballasts fire quicker than the magnetic ones. By the way, starters haven't been used for quite awhile with fluorescent lamps.

The place where I am working is looking at converting thousands of fixtures to T8 tubes and ballasts. They are looking at a 2 year time frame to have everything converted. It will save money in the long run, according to the reports I have read.

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#7

Re: T12 Lighting Fixtures

02/26/2012 2:08 AM

Are you closer to sea coast? Humidity, + salt in the atmosphere=corrosion affects contacts- tube, starter, wire connector everywhere, including switch contacts.

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#8

Re: T12 Lighting Fixtures

02/26/2012 2:13 AM

Sounds like tired starters...

Here's a trick I learned from my father who was a licensed sparky doing mostly commercial work..... Reverse the tubes. Flip them around, 9 times out of 10 they will work again. Have a spare just in case.

Ron, don't do this alone. Have some body help you with the ladder and pass the tubes and starters to you/from you.

Clean the tubes while you are up there. Amazing how much brighter it gets.

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#9

Re: T12 Lighting Fixtures

02/26/2012 12:25 PM

MY fixtures don't have starters.

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#11
In reply to #9

Re: T12 Lighting Fixtures

02/26/2012 2:33 PM

Well, it's probably not the starters, then :-)

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#10

Re: T12 Lighting Fixtures

02/26/2012 2:01 PM

Dueling with moody fluorescent fixtures has been the bane of my existence. Luckily, the old bulbs will work with the new electronic ballasts, just make sure the ballast is rated for your tubes. I keep spare new ballasts handy; if changing the tube doesn't do it, I change the ballast, and install a new tube. Won't have to service that unit for quite a while.

I always write the date on new tubes, lets me know if the ballast is failing. The new ballasts are lighter, that's a plus, fit the same mounting holes.

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#13

Re: T12 Lighting Fixtures

02/26/2012 5:47 PM

Try cleaning the connections for both the tubes and starters

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#14

Re: T12 Lighting Fixtures

02/27/2012 12:32 AM

It seems changing ballast to elctronic type will surely help, though a few questions are popping up my mind......how old are the fixtures.....and what is the circuit length........may be not enough voltage causing voltage dips at starting (if this be case, electronic ballasts will be very very helpful........WORTH A TRY)

Another possibility may be teh fixtures have become too old and tired........in that case no other options but changing all of them...............A TOUGH JOB.....

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#15

Re: T12 Lighting Fixtures

02/27/2012 8:14 AM

Hey ron,

A couple of things about T12's before they're gone. Most fixtures made for T12 came with a magnetic ballast made to meet minimum specifications. The most common type provides power to the coil inside each end prior to starting the lamp. The coil power heats the emitter substance on the coil so that it starts throwing electrons into the gas envelope. Once the lamp starts, the plasma is usually enough to keep the coils heated properly, but some ballasts leave the the heat on while reducing the amount of copper required to keep the lamp voltage where it needs to be.

A variation of this ballast type uses a "starter" that initially heats the coils and then pops the inductive circuit open creating a high voltage (1000 V+) spike to initiate the arc. This type of ballast depends on maintaining the correct temperature at the interface between plasma and conductor (i.e. the coil) simply by controlling the lamp current a little better (slightly higher current).

Both types have problems starting the lamp if you have slightly lower than rated voltage to feed them, or they lose their inductance due to the magnetic core slipping (they are just pieces of coated sheet metal jammed together just enough...). Additionally, if you are using a "shop lamp" or an "energy saver" lamp then the bulb has a gas pressure or mixture that is more difficult to start for other reasons. Two things that might help in that case:

1.) Make sure that the bulb is seated in the fixture correctly (all 4 pins in contact with the conductors in the socket). On the outside of the metallic base is an indentation mid way between the pins. It should be at the lowest point (pointing down to the floor) if you have rotated the lamp enough. Not everybody realizes that. If this is not the case, some coils may not be getting any power to heat the emitter.

2.) If it is an energy saving lamp, then the conductive coating inside the lamp may be poorly applied. You can supplement this by taping a length of wire from one end of the lamp to the other and hiding it on the top of the lamp. The wire needs to run from end to end stopping about 1/2 inch from the metal base at each end. You can just tape it on the bulb. It acts as a starting aid for energy saving lamps.

Other than that, about all you can do is to replace the ballast. If you do, it is probably time to switch to T8 since they will fit the T12 sockets.

I could tell you a lot more, but most people really don't want to know that much about it.

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#16
In reply to #15

Re: T12 Lighting Fixtures

02/27/2012 5:15 PM

GA, Ron, tell us more. I can never learn enough about this kind of stuff. I've tried testing output from ballasts, but there seems to be no rhyme or reason with them.

On another thread I read that the cover right under the lamp plays a capacitive role in the function of the lamp. I was bench testing used fixtures, and none would lite with the cover off. I'll go back and test them with the cover on.

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#17
In reply to #15

Re: T12 Lighting Fixtures

02/27/2012 7:54 PM

Joe:

I'm with MikeK, but I'd like to suggest you start a blog-thread of your own on lighting trouble-shooting, how they work, whatever else you know and that interests you. I have never known enough about how to solve problems with Flourescents in particular. I recently converted some of my T-12 mechanicals to T-8 electronics, and loved them, till a couple of bulbs went out, and when I didn't get to them quickly (like, that week) they blew the electronic ballasts. My brother-in-law is a building engineer in Memphis, TN, and it was at his suggestion I swapped them. When I told him about the problem, and having to replace them, he wasn't surprised, but apologized for not telling me. His buildings use thousands, so they are routine maintenance, and it didn't occur to him that I wouldn't know.

With your help, I might never lose a lighting product due to ignorance again!

I'll read you. Tell me where.

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#18
In reply to #17

Re: T12 Lighting Fixtures

03/08/2012 1:02 PM

Nice idea but I think that it won't be long before fluorescents are gone. LED's rule!

It kind of hurts to say that. I spent 10 years in R&D with a major fluorescent lamp manufacturer. So I learned a few things along the way. I'm just glad to pitch in when I can.

I did get to build a really cool 3 phase plasma fluorescent but it was just for show and tell. No real value in it. Any time you have a question, just look me up.

NYOJ

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#19
In reply to #18

Re: T12 Lighting Fixtures

03/08/2012 2:02 PM

The marina nearby changed out all the fluorescent units in the parking lot for something in a 'can'. I expect some kind of cfl or something that doesn't require a ballast. I'll have to find out what.

The bottom line is, all the flo units are gone, good and bad.

No more up the ladder taking tubes down, putting tubes up, no, that's not it, need a ballast, tubes down again, covers off, switch off, now it's dark, can't see what you're doing, find a flashlight, nope, can't hold the light and work, figure out something else, cut and strip the wiring, drop the ballast, don't get that messy tar on yourself, don't drop the ballast on your head or anything else nearby, hope it's not still hot, ouch, it is, install the new ballast, put covers back on, tubes up, move the ladder out of traffic, which is really peeved by now, and everybody is complaining about the dark parking lot, and go turn the lights on to find your next misbehaving fixture.

No, I won't miss fluorescent fixtures one bit.

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#20
In reply to #19

Re: T12 Lighting Fixtures

03/08/2012 5:16 PM

The next technology - LEDs? will have its own problems and gotchas ......

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