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Light Bulb Question

Discussion in 'Lighting' started by csmith, Apr 18, 2010.

  1. csmith

    csmith Guest

    Is it safe to put a smaller wattage bulb into a light fixture? Lets say you have a 28 watt bulb/fixture, can you put an 18 watt bulb in it?
     
  2. argnom

    argnom Guru Class Expert

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    Hi csmith,

    As far as I know, yes, as long as it's not a halide or high pressure sodium bulb, I think it's all good. What kind of bulb do you have?
     
  3. csmith

    csmith Guest

    Coralife PC. Currently at 28 watts over a 10 gallon. I've found a Current 18 watt bulb, but it's 2.5 inches shorter.
     
  4. Left C

    Left C Lifetime Members
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  5. Blue

    Blue Junior Poster

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    If the hood has built-in ballast, then no, you should match lamp and ballast by power rating. Otherwise, it will 'overdrive' the lamp, which will cause more heat, much shorter life or even destroy your new lamp within seconds.
     
  6. Left C

    Left C Lifetime Members
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    My 20" 28w Aqualight is about 9 years old and I've used 28w, 32w, 36w and 40w square pin PC's in it.

    I haven't tried a lower wattage bulb. It might do what Blue suggested.

    You need to find out if the Coralife ballast is load sensitive. I don't know if it is or not. If it is load sensitive, it's OK. (I think this is right, but I'm not an electrician.)
     
  7. argnom

    argnom Guru Class Expert

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    I though that the ballast was actually included in the PC lamp itself rather than in an external box (such as for good old fluorescent tubes).

    So a 28W bulb would have a 28W ballast included and an 18W bulb would thus have a 18W ballast. I think the wattage rating is there for heat reasons or just because the federal regulations in your area specify that all lighting devices must include a wattage max/min.

    I've seen some funny things happen just because regulations say you have to do it even though it's irrelevant.

    For example, I had a powerhead that had a water level mark on it (the water level mark made it so that the powerhead could not be fully immersed). I contacted the manufacturer and they told me that the powerhead was in fact built to be completely submersible, but the Canadian Standards Association regulations say that any electrical device that is made to be used in water needs to have a water level line... or something like that... and that they were not allowed to put it on the power cord, it had to be on the device itself.

    From Wikipedia:

    Not certain if this is the case for coralife
     
    #7 argnom, Apr 19, 2010
    Last edited by a moderator: Apr 19, 2010
  8. csmith

    csmith Guest

    Left C,
    I actually came down from a Current USA 40 watt fixture. It, combined with my inexperience, was algae's dream. I kind of scared myself with lighting at that point (imagine my terror when Gerryd and Philosophos informed me my newly purchased 2x54 watt T-5HO setting over my 55 gallon was high light :eek:), but I'll keep in mind I can safely move up later if necessary. I'm loading my 10 gallon with stems and was just curious in the case I wanted to drop a little more wattage. I thought about using conduit arms to raise it, but that seemed overkill for such a small tank, not to mention how to safely/aesthetically lift a fixture not meant to be raised.

    argnom,
    The large base of the bulb would appear to hold the ballast. As Left C said, I'm not an electrician so I can only assume how these things work. I'll stick with the 28 watts for now and see where it gets me.

    Thanks to the three of you for the answers.
     
    #8 csmith, Apr 19, 2010
    Last edited: Apr 19, 2010
  9. Left C

    Left C Lifetime Members
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    No. The ballast isn't in PC's. They are a separate part(s). I couldn't find a picture of their ballast like is in 20" 28w Aqualights.

    Coralife 2x65w PC ballast Model: SPL-265R-JS
    [​IMG]






    Take a look at AHSupply's DIY PC kits. The rectangle in the center is Fulham's WorkHorse Ballast. Sorry that it's a twin bulb.

    [​IMG]



    Here's how to wire a single bulb PC and a fluorescent tube with a Fulham ballast.

    [​IMG]
     
  10. Left C

    Left C Lifetime Members
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    I meant to add that screw-in CF's have the ballast in the base, but the linear twin bulb CF lamps that we use need an outside ballast.
     
  11. csmith

    csmith Guest

    Any clue what's stored in the base of the bulb? It's actually pretty cool to see what's going on in there now, I've yet to have a day I didn't learn something here.
     
  12. argnom

    argnom Guru Class Expert

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    Thanks for the info buddy! I actually thought that they were all the same.

    \the more you know...
     
  13. Left C

    Left C Lifetime Members
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    You're very welcome.
     
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