Circuit breakers are simply an electrical switch that will automatically actuate in an effort to protect a circuit from loading or shorting. Its basic purpose is to stop current flow upon detection of an electrical fault. Circuit breakers are beneficial because they can be reset and they function as a protection device again and again as compared to a fuse that can only be used once and will then require replacing.

Circuit breakers are rated for the amount of current that passes through them. They are also rated for the maximum amount of short circuit current for which they are designed to interrupt. 

Circuit breakers are available in different sizes for different applications. They vary significantly from low voltage and low current, to high voltage and high current. If a change from low current to high current is desired, the entire circuit breaker will need to be replaced. There are a variety of circuit breakers that are adjustable. 

For each conductor to be properly protected it is required to have each conductor wired to its own pole on the breaker. Multiple poles can be ganged together to ensure all poles interrupt when one of them is interrupted.