The eternal mysteries of fluorescent lights

[Roger Myers]

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

Not quite as black and white as that... older fixtures (T-12) generally have magnetic ballasts as opposed to electronic ballasts... magnetic ballasts will gnerally have some degree of hum, anywhere from barely noticeable to downright aggravating...this will have to do with the construction of the ballast, how well the laminations inside were vacuum impregnated and so on... To silence them is challenging. Newer electronic ballasts rarely have noticeable hum, are more energy efficient, and generally start well at low temps... the good news is you can retrofit old T-12 fixtures with new T-8 electronic ballasts...change the tubes to T-8 tubes, and save energy, have better light, and quieter fixtures.
Roger

[Al Willits]

Thanks Roger, I posted that in hopes it might help.

Several have mentioned go to the T-8 bulb and changing ballast, seems some of the shop lights I just bought say will work with both T-8 and T-12 bulbs.
Gonna assume that maybe the new ballasts will work for both, but the older T-12 units won't work with T-8 bulbs?

Al

[Roger Myers]

Unless the ballast specifically lists T-8 lamps, then you shouldn't assume they will work... and certainly not optimum for the bulb.

[Al Willits]

Roger, Below is what they say on the box.
After looking at several they offer, looks like some will and some won't.
Nice option for those of us (me) that bought T-12 bulbs and may want to switch over.
Al


48" x 7.5"
Professional quality
Ideal for work areas, garages, utility rooms, basements and recreation rooms
Not recommended for use with timmers, photo cells and motion control deivces
Minimum starting tempeture is -20 degrees F
Uses two T32 T12 or T32 T8 bulbs, sold separately
Dry locations only
Two year limited warranty