What could be causing a buzzing sound in my electrical wiring?

A buzzing or humming sound originating from electrical wiring behind walls or inside junction boxes typically points to loose electrical connections, electromagnetic induction, or a short circuit. The most frequent cause is a loose wire nut connection or loose terminal screw on a receptacle, switch, or fixture, which creates high electrical resistance and micro-arcing as current flows through the gap. Other causes include overloaded branch circuits drawing excessive current, or non-compatible dimmer switches causing electromagnetic resonance in connected lighting fixtures. You can troubleshoot buzzing noises safely by tracking where the sound is loudest and turning off branch breakers. You can verify that your corrective action is successful when turning off power at the breaker, opening the junction box, and securing loose terminal screws or wire nuts completely eliminates the acoustic hum and restores safety.