My entry point for electric service is on the opposite corner of my house. Do I have to run an underground wire, from my ground rod (Point X), all the way around my house to that entry point ground wire(Point Y)?
Yes. It doesn't need to be buried, but a #6 wire around the perimeter of the house (by the shortest
practical route) is the standard approach. You HAVE to be sure that, even with high currents flowing
(as would happen in the case of a lightening strike) there is no voltage difference between the
two ground rods. Otherwise one "ground" point can be a few thousand volts different than the
other. That is not good for equipment or the buildings and people near them.
What if I tied a wire from the ground point of a standard 3-prong house outlet back outside my window to the ground rod, or must it tie in to the ground point in my house service panel ?
Do you know how many splices there are in that wire between your panel and the outlet? Or how
much current might try to flow down that wire? Let's say your computer is plugged into the same
outlet. The power wires are +/- 120V with respect to the power ground rod. What happens if
the green (ground) wire to your computer suddenly jumps up hundreds of volts relative to the
hot and neutral wires due to added voltage drop on the green wire? It's not pretty.