With the panel door open, you can access all the circuit breakers or fuses in the panel. Typically, one of these panels feeds the entire house but you may have a situation where there is another "sub-panel" to serve a specific area such as an addition or new kitchen.
The circuit breakers are stacked in the panel and are controlled with a lever that places it in the "On" or "Off" position. You'll also see a large double pole circuit breaker at the top of the panel called the "Main". It controls all the power to the circuit breakers below it.
Often there are stickers to be placed next to each breaker or a sheet adhered to the inside of the panel door that has space to identify the circuit served by a particular circuit breaker. [
With a service panel having a fuse box, you'll have a number of screw in fuses instead of circuit breakers but the function of the electrical service panel is the same.
