I think the key word here is "portable."
Some folks think that they are somehow improving things if they bang a ground rod whenever they use a portable, or vehicle mounted, generator. I think we've established that doing so accomplishes nothing ... as the ground rod is essentially irrelevant to clearing faults.
That everything in the building needs to be bonded, and that these paths need to go back to the generator, is another subject. That's why I say "switch the neutral;" there's no way for the electricity to go anywhere else.
Naturally, I assume that the extension cords have intact three-prong plugs!
I don't think I have ever run a wire from a genny, directly to a ground rod. Rather, the transfer switch provided the point where the generator ground was tied into the building's ground system. With a portable genny, this is accomplished by that third prong on the plug.
