The answer to 'dimmer switch sparking' is that a sparking dimmer switch is usually caused by a faulty or damaged switch, loose wiring, or overloading the switch. Symptoms may include flickering lights, buzzing noises, and visible sparks or arcing at the switch. Solutions can include replacing the dimmer switch, tightening connections, or ensuring the load (lights) does not exceed the switch's capacity.
If you see sparking or arcing from a dimmer switch, it's best to turn off power to the circuit at the breaker and call a licensed electrician. Attempting DIY repairs on a malfunctioning switch can be dangerous and may lead to further electrical issues or even fire hazards. An experienced professional can properly diagnose and safely resolve the problem.