Integrated Generator Backup Power With an Interlock Kit
Interlock devices allow you to turn your existing breaker panel or sub panel into a generator transfer panel by safely back feeding your breaker panel with power from your generator.
This device only allows the breaker to the generator to be turned on if the main breaker is off and only allows the main to be turned on if the generator breaker is off. Take care when using a interlock device to make sure that your generator can handle the load.
These photos show an interlock device installed on a sub panel here in Oxford, in Chester county.