The power comes in to a main breaker and is usually 100 or 200 amps. Individual breakers then distribute individual circuits (called branch circuits) throughout your home.
These breakers range in size from 15 to 100 amps. Lighting circuits would be 15 amps, outlet circuits would be 20 amps, and a sub panel circuit to a garage or tool shed would usually be 60 or 100 amps.
