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Thread: Do your t-5 bulbs get hot?

  1. #9
    RL7836's Avatar
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    Quote Originally Posted by adnedarn View Post
    I have 2x T5 HOs over my planted fish tank.. it was heating the glass up so much, i now leave it open, and have the lights directly over the water... I was worried the glass was going to break haha
    I use the AH Supply power compacts (which I believe are T-5's in a 'U' shape). They also run very hot, and yes, I have broken several glass pieces on top of my grow tanks.

    Interested in feedback on the T-5 longevity - especially compared with T-8's. As I will need new fixtures in the future, I'm debating between 4 ft T-5's or T-8's (either with parabolic mirror reflectors).
    All the best,
    Ron
    You must do the thing you think you cannot do. --- Eleanor Roosevelt

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  2. #10
    Av8tor1's Avatar
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    RL,

    The lumen maintenance of most any name brand 4' 54w T5/HO is in the 90-95% range through
    out the life of the bulb, which is typically over 3 yrs... and most of the name brand Linear T5 ballast have an automatic shutdown feature before the bulb gets "weak" enough to cause ballast damage (prob results in an increase in ballast output voltage... but that is just a guess)

    everything I've read says that Linear T5's dont really weaken with age... I assume they just kinda die or the ballast tells you its time to put them out to pasture.. check back with me in about 3 yrs

    and if you overdrive with an ice cap 660 ballast, bulb life is suppose to be around 1yr

    I dont know what the T8 specs are nor do I know if any of this info applies to T5 CFL's...

    (pssst I got a 25 count case of some nice German 5000k T5's on ebay for 99 cents, I was the only bidder... woohoo )

    HTH's
    Av

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    RL7836's Avatar
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    Av,
    Thanks for the reply. My post above wasn't very specific. My concerns are with premature failures where the lamp burns out & typically leaves a dark spot on the glass about 1" from the end (sometimes burning all the way through the glass). I posted elsewhere about this with my power compacts. I had switched all of my tanks over to these lights and while I was/am happy w/ the light output & color - the fact that I randomly get these burnouts is a pain. It always seems to happen when I go away for a weekend or a week. I don't know if I ever had this happen w/ T-8's.
    All the best,
    Ron
    You must do the thing you think you cannot do. --- Eleanor Roosevelt

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  4. #12
    Av8tor1's Avatar
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    Ron,

    I do not have the length of experience with T5's to tell you this doesnt occur... but from reading the technical data on the various name brand ballast I dont see how it could.

    Every data sheet I have read indicates that most name brand T5 Ballasts have internal protection from short circuits (excessive current), open circuits (excessive voltage) and bulb fatigue....

    For what you are saying to occur, it would seem to require an excessive current condition (IMHO it would have to take excessive current to generate enough heat to have burn through)...

    I would ask your power compact vendor if their products do in fact incorporates these protections, I would expect them to be proud of the fact if they do...

    Prior to buying my T5 I did quite a bit of research and I have never found any references to problems like you mention..

    but of course caveat emptor...

    Av

  5. #13
    RL7836's Avatar
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    Quote Originally Posted by Av8tor1 View Post
    Ron,

    I do not have the length of experience with T5's to tell you this doesnt occur... but from reading the technical data on the various name brand ballast I dont see how it could.
    I spent quite a bit of time on multiple occasions discussing this w/ the vendor. While I don't recall the various technical terms he used, there is apparently an 'anode' (?) or something similar near the end of the tube. Since the tubes are so narrow, sometimes this part gets too close to the glass, burns a hole & fries the tube. It really has nothing to do with the ballast.

    I would hate to switch to 4 ft T-5's because of this problem and after switching, discover that I still have the same issue.
    Quote Originally Posted by Av8tor1 View Post
    Prior to buying my T5 I did quite a bit of research and I have never found any references to problems like you mention..

    but of course caveat emptor...
    I did a 'decent' amount of research also. Over the years, I found that aquatic gardeners are fanatical as a group and some in that group do amazingly detailed studies on lighting (& pretty much everything else) - much more than the CP folks (I suspect that it's a simple matter of numbers... many more aquarium folks than CP folks). Anyway, there was something close to a clear consensus among that group on the AH Supply lights & fixtures - so I took the plunge. It's not like the tubes fail every day or every week but they often fail at the worst times. The 1st time it happened, I had no spares and almost lost some petios because of it. Since then it has just been a nuisance. I'm not sure if I've had any of the lamps die due to old age...
    All the best,
    Ron
    You must do the thing you think you cannot do. --- Eleanor Roosevelt

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  6. #14
    Av8tor1's Avatar
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    Typically there are resistive heating elements in each end of the tube, when powered they heat up... "boiling off" some of the electrons causing the gas to ionize.

    Once the gas is ionized the an electrical arc can flow from one side to the other, the flowing charged particles excites some of the mercury which partially vaporizes and starts the illumination process

    This sort of gas discharge has a peculiar and problematic quality, If the current isn't carefully controlled, it will continually increase, and possibly explode the light fixture or maybe cause burn through... that I dont know

    In a gas discharge, such as a fluorescent lamp, current causes resistance to decrease. This is because as more electrons and ions flow through a particular area, they bump into more atoms, which frees up electrons, creating more charged particles. In this way, current will climb on its own in a gas discharge, as long as there is adequate voltage If the current in a fluorescent light isn't controlled, it can blow out the various electrical components.

    A fluorescent lamp's ballast works to control this... this is where the bulit in (if so equipped) ballast protection circuits come into play...

    Now i dont know if these protection circuits are a common feature in your specific power compacts... but based upon my limited knowledge this is something i would ask the vendor about... and if it is a case of the cathode resting against the glass then I would have to question their quality control... regardless of source or reputation.


    Av

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