Why does my breaker trip? Overload vs short vs ground fault, and how to tell

Trips after running a while: overload. Too much on the circuit (space heater plus microwave). Move loads or add a circuit. Breakers also get weak with age.

Trips instantly with a bang: short circuit, hot touching neutral or ground. Unplug everything; if it still trips, a wire or device is damaged. Find the last thing worked on.

Trips on a GFCI/AFCI breaker only: leakage or arcing. Old fridges, pool pumps and treadmill motors trip GFCIs; cheap LED drivers and vacuum cleaners trip AFCIs. A dual-function breaker shows which with its indicator.

A breaker that feels warm or trips with nothing on the circuit is failing. Replace it with the same brand and type; this is a 10-minute job with the main off.