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Thread: The eternal mysteries of fluorescent lights

  1. #1

    The eternal mysteries of fluorescent lights

    I have always struggled with fluorescent lamps over the years. It seems like the y just stop working, then start up again. Sometimes I'll swap in new bulbs to no effect. Bulbs I thought were dead work in another fixture. Lamps flicker sometimes, etc.

    After stumling across this site:
    http://members.misty.com/don/f-lamp.html#int0

    ... I may know what is going on. Apparently, on rapid start fixtures (like most of us have) grounding the lamp chassis is important. Not just for safety reasons but for starting reasons!.

    Apparently the capacitance between the bulb and the refelctor assists in starting!

    I recently obtained some used 4 bulb 2x4' fixtures, and I did the normal frustrating dance of bulb swapping with inconsistant results, trying to find a combination that works. I wire nutted a simple lamp cord with no ground onto the thing and was trying to get it to work with poor results.

    After reading the article, I swapped in a grounded cord and shazam! It started working!

  2. #2
    Interesting.

    I just installed my shop lighting, but haven't had any flickering issues.

    Does anyone have any recommendations on reducing humming? I have 8 DBL 4' fixtures, and 2 hum, although I can't locate which ones.

  3. #3
    Join Date
    Nov 2005
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    St. Charles, IL
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    I'd also like to know how to eliminate, or at least reduce, the humming as well. Is it something insode the fixture or ballast which is vibrating?

  4. #4

    T8 fixtures- no hum

    The article discusses hum somewhat. But the real solution is T8 fixtures with electronic ballasts. These run the bulbs at a higher frequency, so there is no hum.

    The T8's I have work really well- start instantly even when the ambient temp is really cold.

    But- I have (and seem to keep getting) older style fixtures and bulbs for free....

  5. #5
    Join Date
    Apr 2006
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    Mpls, Minn
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    Found this, maybe it'll help


    Humming or buzzing in a fluorescent light fixture is usually caused by a ballast that's poorly built or improperly mounted. The hum occurs as electrical current moves through metal plates in the ballast.

    With the power off, open the fixture. The ballast is a metal box about 2 by 3 by 10 inches with wires leading to it. Make sure that the mounting screws are tight. If there are vibration-isolation spacers, check them. Compare this bad fixture to any similar quiet fixtures you may have to identify the problem. It may be necessary to replace the ballast. Also check to make sure that the framing of the fixture is not amplifying the sound. You may need to change the mounting.

    Al

  6. #6
    Join Date
    Nov 2004
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    Thomasville, Georgia
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    Quote Originally Posted by Lynn Kasdorf
    ... The T8's I have work really well- start instantly even when the ambient temp is really cold. ...
    I installed eight 2-lamp 4' T8 fixtures in my existing 16'x24' shop building. I haven't noticed any issue with hum. All eight are on the same switch. One interesting thing about them is that all eight of them come on simultaneously about a second after the switch is flipped. So far, they have operated well at low temperatures -- well, low by South Georgia standards -- down to the upper 30's.
    [SIGPIC][/SIGPIC] Bill Arnold
    NRA Life Member
    Member of Mensa
    Live every day like it's your last, but don't forget to stop and smell the roses.

  7. I'll add something I learned a while ago about the bulbs. If you can, try and get a bulbs with a color temp over 5000K and a CRI (color rendering index) of 90 or higher. The closer these get to 6500K and a CRI of 100 the closer the light is to matching sunlight from an imaging perspective. Makes the colors you see in your shop more accurate and is also a lot easier on the eyes.

  8. #8
    Before we go to far down the lighting brick road, read this post of mine. It's a month or so old, but gets very indepth into choosing bulbs and why.

    http://sawmillcreek.org/showthread.php?t=41349

  9. #9

    Hum

    I read the instructions that came with my last bunch of ballasts. It said to leave them on for the first 48 hours to avoid hum - I did - they don't hum.

    At work I installed T8's with electronic ballast - more light for less power - start fast - never hum - I'll use these from now on.

    I only use "daylight tubes" - I like the color, makes it easier for me to see.

  10. #10
    Join Date
    Apr 2006
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    Mpls, Minn
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    I've just spent a bit over a hour researching lights....add confusion to my learning curve..

    I got some high temp lights 5700 or 6100k I think from Phillips...they had a blue tinge to them, drove me crazy and brought them back, found some high 4000k ones that the guy at menards said were very white and bright...found out only if the garage was over about 65 degree's...brought them back.
    Finally went back to the Sylvania cool white plus for utility and shop usage and at 4100K they ain't to bad, and they work down to 38 degree's, which is what my garage is at when not in use.

    It appears I'm missing the boat here and there are lights out there that would work better, brighter, whiter...but not sure which ones to get.

    I have a Lowe's/Menard's/Home Depot close so anything they have would be nice, don't mind online ordering, but I'd like to make sure they don't end up pink or some other odd color.

    Wandering though any of these stores gets multiple answers and even more confusion.....helpppppp!!!!!

    Considering temps and cri numbers have just confused both the store clerks and myself.
    Can someone please give me a name and model of a T-12 bulb I should try?

    Al...who thought he was well light.....till now...

  11. #11
    My favourite - Sylvania "Daylight Deluxe"

  12. #12
    Join Date
    Oct 2003
    Location
    Seattle WA
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    I have been using them for 5 years with no problems. Only issue I have is slapping them with a 12' piece of wood and exploding them all over the shop.

  13. #13
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    Apr 2006
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    Ok, so if I can find a box of tubes that say "Daylight Deluxe" on them, I'm good to go?

    Thanks, makes life a bit easier for the old guy here.

    Al

  14. #14
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    Yeah, that zero cost factor is what keeps ballast T-12 fixtures in some locations in the shop.
    "A hen is only an egg's way of making another egg".


    – Samuel Butler

  15. #15
    Join Date
    Sep 2005
    Location
    Washington C. H., Ohio
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    I have 14 3-bulb 4' T-8 fixtures in my 16 x 24 shop. The difference is my fixtures all have electronic 277 volt ballast in them. I run them on 240 volts. The trick was to get them to work on regular 110V light switches, and three way at that. I have no hum to speak of and they've come on just fine so far and we've had a few days down in the 20's already.

    Brad

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