Dimmer switches do make a slight buzzing sound due to the interruptions to the electromagnetic field that naturally exists around a live wire. A buzzing sound from the switch is usually not dangerous, unless accompanied by a hot switch or a crackling noise.

Is a buzzing light dangerous?

Buzzing in CFL bulbs is common and is not dangerous. The buzzing is most likely caused by a hum in the ballast. The ballast functions as a resistor, regulating the flow of electricity in the CFL bulb and is located above the bulb's base inside the ballast housing beneath the glass coil or envelope.

Are dimmer lights supposed to buzz?

Some dimmer switches have different operating mechanisms, using a variable rheostat in which it is perfectly normal for the switch to make a very slight humming noise when the switch is moderating the electrical current to dim down the light intensity.