You should establish a GROUND BUSS! No, it is not made by GM, grin! It is a metal bar or plate you can drill and tap or put screws, nuts, and lock washers into! Then run INDIVIDUAL, yes, individual wires from equipment to the ground buss. Run old coax braid or a large SINGLE wire, to the outside ground rod field. This stops what is called GROUND LOOPS. Walt K8CV.