It doesn't go "back out to the ground rod," it goes back to the transformer. Note this paragraph in the parent comment: > And it's not that charge carriers are

It doesn't go "back out to the ground rod," it goes back to the transformer. Note this paragraph in the parent comment: > And it's not that charge carriers are always flowing back to earth, but back to their source. That's why ground is sometimes called a "return path." To move a charge carrier, you need to give it potential. It will lose that potential and return to the point of lowest potential difference from its origin - which is its origin.