Noticeable buzzing from a conventional light switch should not be ignored. Some electronic dimmers can make a faint sound with certain lamps, but loud buzzing, heat, burning odor, flicker, or crackling can indicate incompatibility, overload, or a faulty connection.
Distinguish an electronic dimmer from a simple switch
A dimmer may make a faint sound within its design limits, while a simple mechanical switch should be essentially silent. Identify the control type without removing the wall plate or touching wiring.
Check whether the lamp or load recently changed
Light-emitting diode (LED) lamps that are incompatible with a dimmer, excessive wattage, or added fixtures can create buzzing. Compare the load with the control rating and use lamps compatible with that dimmer type.
Heat, odor, or crackling are stop signs
Stop using the switch and turn the circuit off at the panel only if you can do so safely. Do not remove the wall plate or handle energized connections to investigate the sound.
An electrician can check connections and compatibility
If buzzing continues with a correct load or occurs at a simple switch, the cause may be inside the box. An electrician can inspect connections, device rating, and compatibility without leaving a hidden overheating condition.
Sources
- U.S. Consumer Product Safety Commission — Electrical Safety — Household electrical hazards and safe response to overheating, outlets, switches, and breakers.