If you are looking to install a detached garage, you will need to make sure that you have the proper number of ground rods. The NEC (National Electrical Code) requires a minimum of 2 grounding electrodes for most structures- one being driven at least 8 feet into the earth, and the other being either driven or buried at least 6 feet into the earth. If your local soil has high resistivity, you may need additional grounding electrodes.