Most people understand, too, that the breaker will trip if you overload the circuit with too many things plugged in or with an accidental short circuit. But how does this common device actually work?

It is fairly rare for the main circuit breaker to "trip," because usually, it is individual circuit breakers that trip long before there is a need for the main breaker to shut off.

If the S&P 500 exceeds a 7% one day decline, circuit breakers can be implemented. Here's how they work.