This is the most common cause of a tripped breaker. It usually happens when you're running too many power-consuming devices on the same circuit at the same time. The demand, or load, on the circuit is too high, and presto! The breaker trips to prevent overheating.

What would cause a breaker to trip?

A circuit breaker will usually trip when there is an electrical fault that could cause damage to the circuit. This is usually an excess of current, a power surge or a faulty component.

Will a bad breaker trip immediately?

The purpose of the breaker box is to protect your appliances from a faulty current or faulty wiring. When the breaker detects an electrical overload, it will immediately trip, severing the connection that keeps electricity flowing through that particular circuit.