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Well, this is going to be boring. But can anybody tell me why florescent lights buzz or hum? (nope, this is not a joke.) We have just hung the new lamps in our work shop. They are electronic ballast lamps, two of which are “rapid start”, three are “instant start”. All have the correct bulbs in them. The “rapid starts” are perfectly quiet and the “instant starts” buzz like the dickens. Any ideas??? Thank you, thank you!!!
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Cheap ballasts.
I am not implying that you bought cheap fixtures, but the cheaper ballasts have a tendency to "buzz". Cheap ballasts can be found in some pretty expensive light fixtures, but are most likely to be found in less expensive fixtures such as shop lights, or inexpensive ceiling fixtures.
There is absolutely nothing wrong with the fixture, it will just be noisy. If the noise is a real bother, you can change out the offending ballasts. Most people just ignore the noise, especially if it is in a shop environment where other noises will most likely drown out the buzzing sound.
James
*If you further want to know why cheap vs pricier ballasts hum, there is a phenomenon that is basic material properties of magnetic materials called magnetostriction. Every time the 60 Hz waveform goes from -160V to +160 V, the phyiscal dimensions of the ballast changes, causing hum. To reduce another effect called eddy currents, ballast magnetic cores are laminiated, usually with 4 mil thick layers. If these are cheaply bonded, you get not only the hum from magnetostriction, but also from the laminations smacking into each other. Newer solid state ballasts do not have 60Hz magnetics, and often operate at frequencies above the 20 kHz human limit, so there is no apparent noise. My wife arranged shipping for big GE multi-megawatt transformers a few years back without knowing anything about them except that some won't fit thru the Panama canal. We toured the Glenn canyon dam powerhouse a few years back and saw some of these 4 story tall trnasformers - she said then she understood why the engineers called them "BIG HUMMERS".
*Thanks to you both for the information. The disappointment is that we specifically talked to the distributor about wanting quiet ballasts. This is why we popped for the more expensive electronic ones. We didn't buy fancy fixtures, for sure, but we did spend money for the ballasts. oh, well. Guess we bought a pig in a poke.
*I missed the part about your having electonic ballasts in the instant start also the first time around. If they are relatively heavy, they are not true electronic ballasts.
*Your ballasts should be rated A+ for sound (electronic ballast) or A (magnetic). B,C or D rating will hum more. The rating is listed on the ballast.
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Well, this is going to be boring. But can anybody tell me why florescent lights buzz or hum? (nope, this is not a joke.) We have just hung the new lamps in our work shop. They are electronic ballast lamps, two of which are "rapid start", three are "instant start". All have the correct bulbs in them. The "rapid starts" are perfectly quiet and the "instant starts" buzz like the dickens. Any ideas??? Thank you, thank you!!!