Hi, I just ran across another problem. I will be running 40 amps 240 volts out to my garage via underground 8-3 plus ground. Do I need a grounding rod at the garage or is the ground via the service cable to the garage enough? I have seen both and am not sure why. Is the 240 volt service to the garage required to have a grounding rod at the garage even though there is already a ground wire coming from the main service panel in the house? Any help would be much appreciated! Thanks again.
Regards,
Stevan

In this particular situation, a ground rod is required at the panel in the garage. The neutral in the garage panel must be isolated from the equipment ground bar, wires, and panel enclosure.

This is the short answer, there are reasons that you have seen panels without ground rods, the explanation will be too lengthy for me to go over at this time.

Hope this helps.