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Jacket
12-08-2007, 10:37 AM
I'm almost embarrassed to post this, but I'm stumped. About a year ago, I pulled out all the incandescent light fixtures (3) from my garage, and replaced 2 of the fixtures with standard 4' florescent "shop grade" strips. The 3rd incandescent fixture (which is in between the two florescent fixtures) is bulb-less right now, so I would expect the power to just travel right through it.

Now the problem. They are wired in series to a switch, but 99% of the time, only the first light comes on when I turn it on. The lights "downstream" don't come on. If I wait and let the 1st light warm up, then switch off/on several times, about 50% of the time the second light will come on.

I pulled out all the wires, and re-tied everything last month, and also replaced the 2nd florescent housing. When I got done, the lights (Both of them) worked fine, and continued to work fine that day. But the next morning when I went to feed the dog, it was back to the original state - no 2nd light.:confused:

I don't think its a wiring problem, given that there are random times where everything works fine, and I've double-checked everything. The only decent theory I have is that somehow the ballast-based florescent fixtures somehow interrupt power in the series, and the draw to fire the first fixture somehow prevents enough power from traveling to the second fixture to fire it.

Anybody have any ideas on what I might try next?

Rezarf
12-08-2007, 11:58 AM
Electrical gremlins stink! Sorry Matt, you have done what I would suggest. Have you verified each light works on its own?

Drew

treerootCO
12-08-2007, 12:15 PM
There are new fixtures rated for "cold start" and are not affected by the temperature. The lights I put in my garage only work when the temps are above 40.

http://nemesis.lonestar.org/reference/electricity/fluorescent/trouble.html

Fluorescent lamps do not like cold areas, and standard fluorescent lamps exhibit these symptoms when the lamps are cold. Depending on how cold the ambient air temperature is, operating the lamp may eventually warm the gas inside the lamp to the point that the lamp begins operating at or near its full brightness. The artifacts typically begin when air temperatures around the lamp are below 50F.

If the air temperature is considerably colder and if the surrounding air is circulating, the lamps will never generate enough heat to keep their internal temperatures above 50F, so the lamps will continue to glow dimly and flicker.

The solution here are to use enclosed fixtures that provide insulation from colder air temperatures by trapping a limited amount of air around the lamps. When the lamps are operating, the lamps are insulated from a constant fresh supply of cold air, and gradually the air inside the fixture will heat along with the lamps and the lamps will start to operate normally.

In cases where it is not desired to replace the entire fixture, there are plastic lamp sleeves available. The lamp is inserted into these sleeves and a plastic cap on each end seals the lamp inside the plastic tube, allowing only the electrical contacts of the lamp to protrude. This entire assembly is then placed in the socket in the light fixture. Such sleeves are commonly seen on fluorescent lamps in grocery store freezer units, or in outdoor fluorescent lighting used in commercial locations such as the front porch area of stores.

Fixtures that use the High-Output lamps (HO) are typically found in outdoor signs and other locations where exposure to cold temperatures is expected. These lamps provide most of their brightness down to 10F. They can also be protected to operate at even lower temperatures by using enclosed fixtures or lamp sleeves.

Jacket
12-08-2007, 04:09 PM
Thanks for the ideas

Treeroot - The temperature issue occurred to me, except for the fact that the first fixture always fires up - always. It is definitely dimmer in the cold of winter, which I would expect, but it never fails. The 2nd one, when it randomly lights up, does flicker and stays dim for a while while warming. Dimmer I can understand, but this sucker just stays off.

Dave - Its a 4 wire strand, with the black wire carrying hot but not interrupted with the lights. The red wire (2nd hot) is what is powered through the switch, and then splices into light 1, light 2, and finally the mysterious light 3. The white and ground are also spliced into each light.

The next thing I'll probably do is just remove the problem fixture and rewire into a simple incandescent housing and see what happens. But if it works (as I expect it will), then I'm stuck with ****ty light in my garage, just like I had before....

Jacket
12-08-2007, 04:42 PM
Well maybe this temperature thing could really be the problem. I checked the print on the ballast, and it says its a 50* minimum. The first light might be working all the time because it's mounted on a finished section of the garage, and is much closer to the house/door where it can find more warmth. And the second light worked when I first installed it because it was a warmer day and it took it right from the store and installed it. It's all coming together now.....

Thanks root!

Hulk
12-08-2007, 10:16 PM
They should be wired in parallel, not series.

Red_Chili
12-09-2007, 06:36 PM
Home Despot has low temp shoplights. They seem to work pretty well for me. The 'one bulb' thing may also have to do with seating the bulb in the socket. One of my lights is touchy that way.