Circuit breaker panels serve multiple purposes in a residential or commercial building. In many cases, only one set of electrical power lines enter a home. The breaker panel is the point where the electrical line is broken into multiple circuits that run to areas such as kitchens, living rooms and appliances. So this is the point where electricians break the main circuit into many paths.

The other purpose is to protect the cables from having too much current. This is a safety feature, where a possible over current situation could cause a fire and the individual circuit breaker will trip and therefore interrupt the electrical flow. Circuit breakers are rated by amperage such as 20 amps and by the duration or time of the overcurrent state, such as slow or fast acting. Manufacturers of circuit breakers give electricians and engineers data sheets that explain the use for each type of breaker.

In older dwellings, the panels had fuses, that once they are activated actually melts a small wire inside the small devise and thus the circuit is broken. In these types of panels, a new fuse needs to be purchased and the fuse needs to be replaced in the panel. Since this was inconvenient for home dwellers, more expensive circuit breaker panels with easy reset switches are now the standard.

In the image, shown this panel is labeled showing which circuit breaker controls what electrical circuit in the building.