Some people who grow plants indoors or raise tropical fish use this technique to get more light out of standard fluorescent fixtures.
It basically involves rewiring fixtures employing electronic ballasts so that a ballast drives a single lamp (instead of two lamps). The result is more current flowing through the bulb and greater light output (1.7X the usual output in one typical configuration). The downside described by those who promote this technique is minimal (the bulbs run hotter and burn out faster, in a year or less). The rewiring is not technically difficult.
Has anyone here tried this and had good results long-term? Any major safety issues to consider?
The only one I can think of is the current rating of the contacts in the fixture. If they aren’t rated high enough, they could conceivably overheat and pose a potential fire hazard.
I’m not quite sure I understand the advantage, either, though. If you’re modifying a two-lamp fixture to drive only one bulb, you’re not getting any more light than you would by letting it drive two. In the long run, you’ll burn out bulbs much faster by overdriving them, so your expense will be much higher. Driving a bulb at double the current doesn’t merely halve its lifetime, it’s more like 1/4.
I’ve done this with T-12 4 foot shop lights before. I grow, um, strawberries.
I used a magnetic ballast (because it was cheaper than electronic) that should overdrive my tubes about 80% - 90%, judging on the output wattage.
It was kind of a pain to wire it, as I had to completely rewire the shop lights. The ballast connected with a completely different circuit. The light appears considerably brighter, but I can’t say exactly how much. I have yet to have a bulb burn out in either my overdriven fixtures, or stock.
All of the research I did concerning overdriving, said that it would not significantly shorten the life of the bulbs, unless they were cycled often (turned on and off). Most of the wear on a tube occurs at startup (the initial high voltage burst, especially in VHO applications), and if your lights turn on only once a day (like mine do) you will be fine.
I can’t speak for the safety of the setup, as that has a lot to do with correct ballast choices, good wiring procedures, and the surrounding environment. In reality, most fluorescent bulbs are under-stressed. They deal with the extra wattage very well.
What you can do is take a fluorescent ballast that is hooked up to two tubes in a typical shoplight-type fixture, and rewire it to a single pair of sockets. Then you do the same with the ballast and sockets from another shoplight and combine the two pairs of sockets and two ballasts within the frame of a single fixture. That’s where the 1.7X amount of light comes from - the output of the two tubes driven by two ballasts, as compared to the output of two tubes driven by a single ballast.
There’s a discussion of the technical and practical side (with diagram and photos) here.
I sort of figured this might be a popular concept amongst the strawberry growers of America.
My application would be in starting seedlings of ornamentals and vegetables. The optimum for a fixture is high light output and low heat, so you get nice stocky seedlings. I could use an HID fixture (HPS or metal halide), but they are much more expensive to buy, more expensive to run and put out a lot of heat. An overdriven fluorescent light setup can be had for maybe $15.
I don’t understand - which question of yours didn’t I answer?
I used one very powerful ballast per 2 tubes, versus your 1:1 setup, but the theories are the same. You just have a little more wiring to do than I did.
