An overloaded circuit is the primary reason for a breaker tripping and occurs when a circuit is has more connected electrical load than it is supposed to have. When more current runs through the circuit than the circuit was intended to take, the circuit breaker is designed to, well, "break the circuit."
Circuit breakers come in different ratings that determine how much current they will allow to flow through the circuit. If a 15 Amp circuit breaker is protecting a 15 Amp circuit, and 20 Amps of current start to flow through it because a hair dryer, TV and small personal heater were all connected to the same circuit and were on at the same time (even if on different outlets) then the circuit breaker trips to prevent overheating of the circuit.
- The most probable reason the breaker tripped is that you simply have too much plugged into one outlet or multiple outlets connected to one circuit.
- Move lamps, heaters, irons, hair dryers and other heavy power consuming devices to a different circuit not being heavily used; or
- Turn off some of the devices on the circuit to reduce the load.
- Loose connections are another possible but less common cause. With power off, check outlets for a loose wire and the electrical service panel hot wire connected to the circuit breaker to see if it has become loose. Retighten the connections if necessary.
- If these suggestions do not solve the problem you may have a more serious problem such as a Short Circuit or Ground Fault.