Here are the rules, as I understand them:
— Each lightning target requires a ground rod ( or electrode). Exception: One multi wire branch circuit (or less) needs no such electrode;
— All grounding electrodes need to be connected into the same network; and,
— These connections may be “indirect;” that is, by using the ground wire in feeder circuits.
Some examples:
— A house with a detached garage. If the garage has but one MWBC, no grounding electrode is needed. When there is a grounding electrode, you can bond that electrode to the sub-panel you have in the garage. The green wire between the sub-panel and the house panel will suffice to “connect” the electrodes into the same network;
— The cable guy drives in a little rod of his own. You need to connect his rod to yours. You can do this directly (by running a wire from his gear to the inter system connection block) or indirectly by landing his wire on the ground buss of any convenient panel; and,
— For whatever reason, you install your two rods to opposite sides of the service. You can either run your GEC from the panel to rod #1 and then on to rod #2, or you can run separate GEC’s to the ground buss of the panel.
