irregardless is a generater is bonded or not does not determine if a ground rod is required, just as a ground rod is not required for light poles. Remember that a grounding electrode system is on the line side of a service. The Bonding main is on the load side. Two, often confused topics. As a back up power supply does not generally require a ground rod since it supplements an existing system. If the generator is used to supply power lets say for a construction site that is not serviced by a utility, then it would need a ground rod. It not wrong to install a ground rod with a genset providing it is tied to the grounding electrode system for zero potential.
