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rockymountainchile

overdriving fluorescents

rockymountainchile
19 years ago

I have read a number of posts refering to "overdriving" fluorescent lights"... I am curious about what that does. More intensity/lumens? How is it done? Etc...

Comments (25)

  • FLAME747
    19 years ago

    Hey,
    I've ben asking the same question, but i looks like this question had been asked so many time that the ole timers are sick of it, anyhow i overdrove 4 2-tube fixtures over this weekend, WOW i've got a lot more light, don't have a light meter, but i can tell with just 2-fixtures "4-tubes> i got more light than i did with the old 8-tubes. with all 8 light it is very very bright.

    I've posted some pic's on this forum on how i wired the ballast, note: i am not an expert, i just connected the wires, crossed my finger, and flicked the switch, so far nothing blew up, and the house is still standing :)

    I 've have to watch my plants over the the month, to see how they are responding to the new set up.

    good luck

    Here is a link that might be useful: pics of ballast

  • korney19
    19 years ago

    Flame, congratulations, your wiring looks like you did it exactly the way shown in zink's pic for a 4-light ballast.

    Rocky, see the link below, it's the current overdriving thread but I believe somewhere in it is a link to the original, I think on someone else's site.

    I have asked a couple questions and started a thread, as well as answered a couple questions where I could, and this forum doesn't seem as user "friendly" as others such as the tomato forum where I often answer someone's questions within minutes or often don't mind discussing their problem off-list.

    Maybe all the Maytag repairman are really out on the job & not sitting around with any time on their hands like the commercial makes us believe! lol. You got lucky that someone read your post and answered relatively quickly--it took me a couple days to get a reply, and it wasn't exactly like I was asking a bunch of the same questions--I read all the back pages for answers before I ever posted. And some of those threads are really stale--going back months, some even started a year ago or more.

    Thanks do go out to lightmaster, I appreciate him replying to my thread. Some of the other "experts" look like they're too busy--so much that they don't even have e-mail links in their member pages, or they come & go, & answer as they wish--when they wish. Or maybe it's just a big difference between the "flower people" and the "veggie people?"

    Mark

    Here is a link that might be useful: I have found the BEST cheap flourescent ballast/fixture - cont'd

  • shrubs_n_bulbs
    19 years ago

    Mark, this isn't a particularly busy forum. Less people means a longer wait for replies. The advantage is that almost everything ever discussed is still here if you go back a few pages or do a search.

  • korney19
    19 years ago

    Thanks shrubs. Maybe you can check my SL16? thread and see if you can add anything? There's still alot of questions imbedded in my style of writing that went unanswered, though some may be country specific, or some even opinionated.

    I'm sorry my writing style gets so drawn out sometimes, but I often feel posting details-details-details can save alot of questions. Sometimes people tend to breeze over/thru it when it comes to reading, and those of which I'm asking question of end up asking me questions, but I really try to cover everything from the beginning.

    Being specific is something I try to do, especially on a forum, where not only does the poster has to wait for answers but the replier asking something must again wait if he/she asks a question back. It's not like a telephone conversation or even a chat room with instant replies. Being grateful to those offering help, I'd hate to make them wait for an answer back from me.

    Stop by the tomato forum sometime.

    Thanks.

    Mark

  • shrubs_n_bulbs
    19 years ago

    Mark, you must have mistaken me for someone who knows how to overdrive a fuorescent :) I don't. Or rather I do, but only on a theorectical level. I couldn't tell you which ballasts are suitable, or which coloured wire you need to use in which make of fitting!

    I don't overdrive because it is an extremely inefficient way to produce light. I consider there are better ways to produce the lumens I need, expecially in the moderate intensities that I need.

    One last thought, Mark. I find that if you post a list of, say, five numbered questions, I will make some attempt to answer the five questions. If you post a page of text asking the same five questions, I might get lost and write a page of general waffle in reply :)

    Here is a link that might be useful: Mark's overdrive question

  • gawdly
    19 years ago

    Wow, someone's a bit impatient and feeling looked over...sheesh. Contrary to what you may believe, Mark, you're not ignored because we don't like you, you're ignored because many of us aren't the overdriving experts. Zink is the resident expert and he's only here from time to time.

    Like Shrubs, I don't do overdriving because of the PITA that is can be to get the proper ballasts and would rather use other formats for lighting like Compact Fluorescent. If you want to talk about configurations of lights, general wiring, light coloration or compacts, I can help you-just not for overdriving.

    Sam

  • lightmaster
    19 years ago

    I can be an assistance on the overdriving part, Kelvin Range, and anything that has to deal with fluorescents. (I don't bother with the HID stuff.) I try to get questions asked when I have time.

    I don't mess with HID because they run hot and the sightest power drop will cause the fixture to shut off, cool down, and restart. That may take minutes.

    -j-

  • rockymountainchile
    Original Author
    19 years ago

    Thanks for the info folks. Great links, pics & diagrams. One question remaining before I give this a shot; Am I correct in assuming that the second ballast used to overdrive a 2-light fixture maintains its own power cord vs. trying to run both ballasts off of one power cord?
    And thank you again for the input.

  • gawdly
    19 years ago

    AFAIK, you would wire them both to the same power cord. I can't see any advantage to wiring them seperately, and it would be a huge PITA when starting them up or shutting them down. One cord, 2 ballasts, 2 tubes...

    Sam

  • jkirk3279
    19 years ago

    "Am I correct in assuming that the second ballast used to overdrive a 2-light fixture maintains its own power cord vs. trying to run both ballasts off of one power cord? "

    !!!!

    Uh, NO. Best case, you might get by fine. Worst case, you'd have a fire.

    If you treat each tube as a separate light, you'd be fine. If you tried doing a 2X overdrive, you'd be in trouble.


    All because of a little thing called Phase. AC circuits work with a sine-wave pattern, alternating on and off at 60 times a second.

    If two appliances are connected to EACH other, they must be in lock-step phase-wise.

    If you use the same power cord for both ballasts and pair white-white black-black, you KNOW everything's kosher.

    But, suppose you used separate power cords. And suppose one set got reversed.

    You know how all modern power cords have one wider blade? That's to prevent a disaster that occasionally happened.

    Imagine this. Back in the day, a fellow plugs in his computer to one outlet, and doesn't have enough plugins to power his printer.

    So, he plugs the printer in across the room and runs the printer cable under the carpet, across the room to the computer.

    Now, what's wrong with that?

    The outlet across the room was on a different breaker, and accidentally out of phase with the outlet powering the computer.

    This meant there was a potential difference of 240 volts between his computer's power supply and his printer's power supply.

    If the two circuits had been IN phase, they would both be ON at the same time and OFF at the same time, so there would be no potential difference.

    But they were OUT of phase, so when one circuit was ON the other was OFF. Leaving a total amplitude of 120 volts times two between the highs and lows.

    Guess what happened? Computer, printer, cable and rug, all burned.

    Power flowed through the computer, through the cable, into the printer, FSSSST !!!

    So, NO, don't do that. That wider blade on the power cords is to make sure that all the cords plugged into that circuit end up with the same phase.

    I try to imagine what would happen if somehow you had two ballasts (in the 2X configuration) hooked to one tube.

    Ouch.

  • rockymountainchile
    Original Author
    19 years ago

    Thank you... guess it should have been obvious.

  • shrubs_n_bulbs
    19 years ago

    Another urban myth.

    Plugging multiple components into AC power with different polarities isn't dangerous unless the appliances are faulty. If they are faulty because the AC supply is not correctly isolated then they are dangerous however you plug them in. Many countries don't even control the polarity of socket connections (although this is dangerous for the simple fact that an appliance may still be connected to the live supply even after a fuse has blown) and surprisingly many people are still alive.

    More likely, this little fire was caused simply because the split-phase supply was incorrectly wired. The polarities of the two phases in a normal US split-phase domestic supply should always be such that the voltage across them is 240V. Then the single neutral wire common to both phases carries only the difference in loads between the two phases. If the polarities between the two phases is incorrect then the common neutral return wire carries the sum of the loads in the two phases. An overloaded neutral wire can lead to a fire.

  • shrubs_n_bulbs
    19 years ago

    Or maybe the problem was simply the wire run under the rug? That's a big no-no.

  • jkirk3279
    19 years ago

    A primer on AC wiring.

    I found it thought provoking. The author points out that many people forget that electricity is more complicated than "Red is 12v and Black is ground".

    And he's right. Many times I've been working on something like re-wiring a console for a motorboat and been heard to grumble about the rat's nest of wiring I find in boats.

    Here is a link that might be useful: AC

  • shrubs_n_bulbs
    19 years ago

    Don't get me started :) Some of the wiring in my house when I moved in would have been funny if it wasn't so dangerous. Single phase 240V over here so no point going into details, but I learned you can be pretty creative about getting electricity to an appliance if you don't care about codes or safety (hint, one light fixture was wired to two different breakers!).

  • jkirk3279
    19 years ago

    Oh, that's right, you guys use 240VAC 50 Hz.

  • object16
    16 years ago

    Hi, I found zink's original thread by doing a google search on
    overdriving t8. everything is explained and illustrated.

    http://forums.gardenweb.com/forums/load/lights/msg0318151130401.html

    I have just bought some t8 fixtures from HD in Canada, Lithonia type, and placed an ebay purchase for a lot of 20 ballasts for $125 US. The fixtures are for two lamps, width of 6 1/2 inches, so overdriving will be of practical benefit, as there will be 4 lamps per 13 inches x 48 inches. If I can get 5000 lumens out of a 3050 Ushio T8 850, 2$ per lamp from businesslights.com, then this might give 5000 lumens per square foot. This is a Lithonia fixture with a curved reflector. I plan to line the reflector with mylar to increase the reflectivity further.

    I am planning on growing roses throughout the winter, and high lumens would probably be appreciated. I have just rooted some cuttings taken at the end of August, and am planning on taking a few more trays of cuttings while the weather lasts.

  • object16
    16 years ago

    I just tried overdriving one lamp with a single 0.45amp 2 lamp ballast supplied with the fixture. It was a piece of cake. I just wiggled the blue wire a little while pulling on it, it came out, and I stuck it in the spare hole in the other socket, next to the other blue wire, and let er rip! The lamp is blazingly bright! I compared one lamp with stock wiring, and the illumination of my son's bedroom. The overdriven lamp is obviously way brighter, and there is almost an unnatural brightness coming from the room. Like forbidden fruit! Yeee haw!

  • object16
    16 years ago

    Oops, my post gave the wrong url:

    That is the one that goes to zink's page, with discussion and photos:

    Here is a link that might be useful: Zink's thread

  • object16
    16 years ago

    I find a useful source of ballasts is actually on ebay. I have been collecting AAA instant start ballasts with power factor over .97 for about $5 apiece, including the shipping charges. It's a nice big ballast that runs nice and cool.
    The only problem is that it's too big to fit in the stock enclosure, so I had to mount them on top, and use some grommets to pass the wires into the fixture.

  • maimonides
    14 years ago

    I wanted to ask about overdriven t5HO, since these when overdriven appear to have tne potential for producing outputs close to HIDs.

    Ex: Two 8-lamp T5HO setups (total of 16 bulbs), when overdriven 2x will put out 1.7 times their rated output. In this case that would be 16bulbs X 5000 lumens per bulb = 80,000 lumens. Multiplied by 1.7 (when overdriven by factor of 2) give you 136,000 lumens. That is on par with a 1000w HPS, which get around 140,000 lumens. Here is the question: Does anyone know how much wattage an overdriven bulb actually consumes?

    If you overdrive an 8-bulb sunblaze that normally runs at 432 watts (8x54 watts) 2x by putting on two extra 216w ballasts, so that you have a total of four 216w ballasts, each powering just two bulbs, then the AVAILABLE power from the ballasts would be 128 watts per bulb, or 864 total watts. Now, would power consumption actually be that high? Would that be USING 864 watts of electricity? Do overdriven bulbs draw and consume ALL the wattage made available to them?

  • klinko16
    14 years ago

    Hi, I use two ballasts per fixture, which is a 32W x 2 T8 shoplight basically. The overdriving configuration means I run 54 watts per 2 lamp fixture. I run 11 fixtures back to back for a 4x6 foot panel. I use the knockouts in the fluorescent fixture to run my wiring. Basically, the ENTIRE PANEL is supplied by only ONE 120V ac wire, controled by one wall switch. this method is the simplest, and it works fine. if u just have 2 ballasts and one fixture, then just use ONE a.c. supply line for the two ballasts and one fixture.

  • zink
    14 years ago

    maimonides,

    The 2X overdrive figure of 1.7 which you used, as a rule, only applies to the 32wT8 e-ballasts, in my experience. I have played around with overdriving a variety of other ballast/lamp types and found they can vary from an increase of 1.2 to 1.7. Based on experience, I would expect a 54wT5 ballast to OD less than 1.7, as most other different wattage ballast also did.

    Oddly enough, if you overdrive a 54wT5 lamp with a 32wT8 ballast, you get a throughput of 460mA, which is the EXACT 54wT5 specified recommendation. Thus, I built my 54wT5 fixtures using OD'ed 32w ballasts. I then get the correct designed output.

    There are some things you need to know about the T5HO's. They are designed to operate at 10ºC higher than T8's. The T5's are also designed with about one inch of glass on the printed end of the bulb which does NOT include the internal volume of the lamp. Look at it carefully and you will see what I mean. This is the designated "cold end" of the lamp. If the bulbs are getting too hot during operation and are losing luminosity as a result, you are supposed to make sure that the bulb is oriented so the printed end (cold end) gets the most ventilation, if possible.

    Zink

  • zink
    14 years ago

    maimonides,

    I just reread your post. I don't understand what you mean by
    "Do overdriven bulbs draw and consume ALL the wattage made available to them?"
    What do you mean by "made available"? I might be able to speculate if I know what you are asking.
    I do know that the ballast itself consumes less than 4 watts per individual lamp circuit and the bulb uses the rest. The lumens-per-watt ratings generally reflect the increase in wattage consumed by the bulb as long as the temperature is kept within specs. It isn't easy to keep an overdriven bulb as cool as it should be with more current flowing through it, but the lm/watt will hold true if you keep it cool, up to a point. I did find that various manufacturers indicated this in some of their more detailed literature.

    FYI: I just found the results from when I once powered a pair of 54wT5HO lamps with several ballasts intended for larger lamps. I did NOT rewire the ballasts in an overdrive mode, but I did use higher power ballasts and compared the current throughput with the 54w lamp's specification of 460mA per tube.

    Ballast ------- Wattage Over Spec
    SOLA
    E-758-F-259 ----1.17%
    Advance
    REL-2P60-S ----1.48%
    Advance
    REL-2S110 -----1.30%

    The percentages should reflect the increased light emitted. I do believe the lamps also ran very hot when I did this.

    Zink

  • xmaslightguy
    14 years ago

    I think by "consume ALL the wattage made available to them"
    he meant basically "do they use 2x the wattage"

    So assuming that i'll try to answer: it doesn't quite
    work that way. The '2x' label can be confusing...As you
    already know you don't really get double the light, but
    nor does it double the power taken. (this is just the way
    ballasts work): Say for example a 2x overdrive gives 1.7x
    the light, it will also be using approx 1.7x the amount of
    power (may be slightly more because its not quite as
    efficient).

    ---------------------

    Also Maybe i'm wrong here but my understanding (from
    reading stuff on the net) is that
    T5HO bulbs are basically overdriven normal T5's
    (much like T12 HO or VHO are basically an overdriven normal T12)
    [if i remember right the higher output bulbs just have higher-rated filaments & thicker glass]
    and that it would be pointless to overdrive any of these?

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