I am using 230v to 240v fluorescent light transformers for T8 36W 120 cm fluorescent tubes, but I found that the transformers are buzzing.

The buzzing should not be happening, even though it is new and very high quality. I searched for the reason and found that the input voltage is 250v.

Here is a picture of it: enter image description here

Do you think this is the reason? and can anyone describe why this is happening?

the transformer i am using

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Buzzing is usual to those kind of ballasts.

However, the reason for excessive buzzing might be that your input power is provided from an inverter that generates pseudo-sinusoidal wave. The excessive THD may produce spikes that are beyond ballast's ability.


LN36.201 is not a transformer It's a ballast. It's an inductive current limiter - a series coil for your tube. Without it your tube would drain, once ignited, as much current as there is available until the fuse blows.

Because they are coils, they also act as electric magnets and vibrate. That makes the sound if anything is slightly loose. A few drops of glue can fix the problem, if the moving (=buzzing) seam is visible and has no electricity. You can easily test if something is loose by pressing the ballasts by hand and this way suppressing the vibration.

250V is a substantial overvoltage. It makes the ballasts more noisy because the current is higher. The current in theory is at 250V only 8,6 % bigger than at 230V. In practice the difference is bigger because the iron core in the ballast start to get saturated and it does not limit the current as effectively.

Addendum: Light dimmers and DC-->AC Mains converters often produce distorted, non-sinusoidal output voltages. Those can easily to be heard from the ballasts as increased buzzing. Ballasts are originally designed for sinusoidal AC voltage.

  • 1
    Do they still use mag ballast on your side of the pond? They were outlawed in the U.S. back around 2002. Most our modern ballasts can run on anything from 100v-277v. As far as over voltage that shows 240v and that is nominal voltage +-10% would be the normal operating range in most cases. – Ed Beal Jan 25 at 20:21

The ballast shows a table with 2 options but no wiring diagram with 2 options and since you said "i am using a 230 - 240 V fluorescent light transformers for T8 36W 120 cm Fluorescent tubes" I assume you are only using 1 tube per ballast.

If two per ballast , it will make noise in parallel but not in series.

Personally I prefer Phillips quad output magnetic ballasts , each 4 independent that do not all have to be used for 1m 32W T8 tubes with triphosphor and high efficacy 88 Lumen/w tubes.

Voltage tolerance should be at least 10% or +/-24V


Buzzing sometimes means that the ballast is saturating (which can be caused by DC current). One source of DC current, is rectification inside the fluorescent lamp tube. Try removing the lamp (tube), and reversing its direction. Or, fit a new one.

Another source of buzzing is overcurrent; replacing a 40W tube with a 36W tube might be effective.

That ballast has a date code (01) indicating 2001 manufacture; modern ballasts (electronic, almost all of them) might be available to retrofit your fixture, and will usually be more energy efficient than the magnetic ballasts of yesteryear.


This ballast obviously a vacuum impregnated finishing and contains no loose parts to vibrate or hum. The source of the noise you hear most likely from the lamp casing in which the ballast is mounted.

The casing normally made from sheet metal which reacts physically to magnetization fields of the ballast.

You can correct this by mount the ballast tightly with additional screws.

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