The installation of an electrical subpanel allows the addition of new circuits and breakers when the main electrical panel is full. One thing to consider before adding a subpanel is the anticipated load of the system in comparison to the available electrical service. Proper placement and access are also important.
Electrical subpanels are especially handy when adding service to a shed, garage or new addition. The subpanel can be located closer to the new service, reducing redundant wiring and voltage drop. Subpanels can also be used to wire levels of a home separately, so that a tripped circuit on the second floor can be addressed without going to the main panel downstairs.