Why is my ceiling light making a buzzing sound?

A ceiling light fixture making a continuous buzzing or humming noise is typically experiencing mechanical vibration or electrical waveform incompatibility. Common causes include inexpensive or non-dimmable LED bulbs struggling with phase-control dimmer switches, loose terminal wire connections vibrating under current, or failing magnetic ballasts inside older fluorescent fixtures. As electronic dimmers chop alternating current waves, the internal drivers inside the lamps can resonate audibly. You can troubleshoot acoustic symptoms safely by shutting off power at the circuit breaker before inspection. You can verify that your corrective action is successful when replacing incompatible lamps with certified dimmable LEDs or tightening loose fixture hardware eliminates the acoustic hum entirely.