If you are adding a full house generator that will be hard-wired to your home you will need a permit. The Residential Remodel/Generator permit requires a survey of the home, a copy of the manufacturer's specifications of the generator being installed, and the gas source. If propane will be used, the location of the tank is required on the survey. If natural gas is being utilized and the line has to be extended, you will need a permit to extend the gas line. Electrical and Gas inspections are required.
You will find the applications by clicking this link - Building Permits
If you purchased a generator from a local hardware store that requires fuel and is not wired to your home, you do not need a permit.