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T12 fixture wiring -- where should the white wire end?

Posted by jrrrr 9b (My Page) on
Thu, Mar 8, 07 at 20:59

I bought a T12 assembly that is 100% straight forward to put together, except there is a long white wire coming from the electric cord input that doesn't seem to go anywhere.

There's nothing in the instructions about where to connect the wire. I don't know much about fluorescent lighting, so I'm not sure what to do with it.

The ballast seems to ground to the fixture and the reflector seems to ground to the fixture via two metal screws. Do I connect the white wire to the reflector with a screw?

There's a bonus pic of the ballast. The light in question is an American Fluorescent 234UTAH shop-lite.

Thanks for the help.

Follow-Up Postings:

RE: T12 fixture wiring -- where should the white wire end?

Back the camera off a bit and take another pics of all the wires. Following the diagram on the ballast indicates that a white wire comes from each lamp and connect to one of the input wires. The other input wire goes directly to the ballast, probably a black wire.

Until you know, don't hook it up. You don't want one of the input wires to connect to the reflector. Is this a three wire input, or just two, a white and black?

RE: T12 fixture wiring -- where should the white wire end?

First post updated with new pics.

Deweymn, this is a three-wire input with the center wire grounded to the fixture. The black input wire does go to the ballast. Are you saying that the long white wire from the first input plug should be joined in parallel the white U-shaped wire (on the other side of the fixture) in the first picture? Is the U-shaped meant to wire those two bulb sockets in series?

RE: T12 fixture wiring -- where should the white wire end?

A common colour coding for three-pin power cords is black (or sometimes red) for live, white for neutral, and a bare wire for earth. Both the live and the neutral wires are normally connected directly to the ballast, usually right next to eachother. The earth usually connected to the fitting or reflector but sometimes to the ballast.

RE: T12 fixture wiring -- where should the white wire end?

Looks like there is a diagram right on the ballast?

If so, take a picture.


RE: T12 fixture wiring -- where should the white wire end?

shrubs, the earth wire is connected to the fixture. The black live wire goes into the ballast. There's no place for the mystery white wire to plug into the ballast, though, and the white wire is the length of the entire fixture.

Ballast closeup:

RE: T12 fixture wiring -- where should the white wire end?

dcarch, in her first pics she did produce a photo of the ballast wiring diagram. On it the black wire went directly to the ballast as she now states. On the ballast wiring diagram again they show one wire from each lamp joining together and then connected to the incoming neutral wire. Not the way I find most ballasts. All of the ballasts I work with take the incoming wires and connect directly to the ballast with a ground wire, bare usually just connected to the fixture for safety reasons.

Until I had a clearer picture I hesitated to say more although I am sure the white wire does not connect to the fixture.

jrrr, on your pic of the ballast above, I assume the thicker black wire is the incoming power cord? And the one black wire of this is wire nutted (the clear connector) and then goes to the ballast. What does the other black wire of this incoming power cord connect to? It appears that this 2nd wire is wire nutted (another clear connector) to the white wire that is loose in your first picture?

Referring back to the first wiring diagram on your ballast I would say that the white wire in question came out of one of the holes next to the white wire that loops from each plastic end piece in your first pic. That would follow the diagram on the ballast as they are using the end plastic piece as a connector.

If foreign companies had quality control departments like we used to have here, that fixture and any else produced by that line would be scrapped or at least inspected individually before shipping. But that was a long long time ago on a planet far far away.

I would return the fixture if that loose white wire won't slip into the hole next to one of the white wire loop. Once in you should not be able to pull it back out easily but since it is 'hot' when the fixture is plugged in I would not want it to be a loose connection. That could spark and soon melt the plastice end piece of the lite tube.

Hope this makes sense. If you post any more pics, pull some of the same color wires out a bit so they photo individually. Won't hurt any thing and you can test the fixture without the cover plate on. Once you insert that white wire of course.

RE: T12 fixture wiring -- where should the white wire end?

deweymn, you are correct that the black wire that goes to the ballast is wire nutted to the first input wire. The long white wire is wire nutted to the second input wire, and the green fixture ground wire is spliced into the center input wire.

I inserted the long white wire into the third plug from the left of the red wire in the first picture. In other words, in the right socket, the long wire is plugged in next to the U-shaped white wire. It slipped in easily and isn't pulling out easily.

I had a feeling the white wire might have fallen out of one of the sockets. I agree that this fixture isn't the picture of quality, but it only cost $8. I'll test the fixture and check back in if things don't work.

Thanks again.

RE: T12 fixture wiring -- where should the white wire end?

Yes, the wiring diagram indicates that the long white wire direct from the power cord goes in next to the short white wire loop between the two end posts in your first picture.

Personally, I don't like having the mains neutral wire connected directly to the tubes. Your mains circuitry is not designed to take any part in handling 600V or more. Treating the neutral wire as if it just sits there at 0V doing nothing is a poor design from a safety standpoint.

RE: T12 fixture wiring -- where should the white wire end?

Interesting add to this:

I got a light from my son who was doing some remodeling in an older apartment building. It had been on the ceiling.

It was a florescent light from the fifties or sixties I would guess. Had two engraved glass decorative ends covering where the plastic tube holders are. It uses two 24" tubes.

I opened it up and found that the old ballast (could be original) was wired like the pic jrrr posted. A loop for the neutrals and one input wire going to one of the contacts of the loop. To connect wires they had slotted screws for attaching each one. Each tube also had a FS-2 starter in addition to the ballast.

I'm going to clean it up and rewire it with a new ballast although it was working when he removed it.

RE: T12 fixture wiring -- where should the white wire end?

Any fluorescent fitting with a starter, or for that matter any ballast from more than about 15 years ago, will be magnetic. Throw it away and get yourself an electronic one. More light, less electricity, tubes last longer, buzzes less. A free magnetic ballast is still too expensive ;)

P.S. But then I would never use 24" fluorescents anyway, LOL.

RE: T12 fixture wiring -- where should the white wire end?

I agree but you misunderstood. I wasn't going to use that old fixture for my plants. I'll see what it looks like when I strip the paint off and repaint it. As for my grow lites now, they are all recent T12 fixtures.

I probably won't get at this for this years seedlings but I have a box of new T8 ballasts and tubes for 3 or four light fixtures. Plus plenty of ends. On my next set up I will probably use those and build my own frames to hold the bulbs.

Those bulbs I mentioned earlier were not from a dollar store but rather were donated to a charity thrift store. Turns out they were all new GE bulbs that someone had donated. Perhaps they sat on someones shelf or a business donated them. But hey, at $1 apiece I'll find use for them. I've got a snake and a tarantula set up that each use florescents, tho I prefer the reptile lites for the snake.

I've also got access to a 96" fixture. No room in the house to use that but I could rig something up in the garage or shed but I would have to have heat too. Wouldn't be cost efficient if I gotta run elec heat too.
Hopefully my winter sowing containers will work out and nature can provide the light.

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