A picture is worth a thousand words. Much of the confusion about grounding, earthing and bonding is due to lack of understanding or misunderstanding the terminology used in the NEC.
The Mike Holt website is loaded with information, accompanied by illustrations that clarify the code requirements and clearly explain the reasoning behind them.
Check out any one of these topics:
http://www.mikeholt.com/newslettersCategories.phpOf particular interest regarding this discussion (one could spend hours exploring this topic alone):
http://www.mikeholt.com/newslettersArchive.php?list=GB-HTML&back=articlecategories.phpOne thing made clear in my own case, the stock Gates BC1-T as it is wired at the factory is in violation of the code because the a.c. neutral is bonded directly to the metal transmitter cabinet. I separated those as one of the very first modifications, when I converted the transmitter.
According to the site, there is one violation in my hamshack installation. I run a three-wire feed from the main panel in the house (two hots plus neutral) to the shack, enclosed in buried plastic conduit. I also run a bonding wire from the ground rod at the shack to the one at the service entrance. The neutral at the shack is not connected to the ground rod, but is insulated and treated the same as the two hot wires. I run a separate #4 or #6 (don't remember which) wire between the two ground rods. According to the site, I should have run a bonding wire, in addition to the neutral wire
inside the conduit along with the three conductors. Mine is outside the buried conduit, buried separately a few inches below the surface, and runs between the two ground rods. But since the earth is not depended upon for the return of ground fault current, I don't think this is a serious concern. In any case, it would be virtually impossible to add a bonding wire inside the conduit without digging up the whole system, and I'm not going to do that.
I experimented one day, temporarily connecting the neutral where it arrives into the shack to the ground/bonding wire (which would be a code violation if connected permanently), and the resulting ground loop induced hum in both my transmit and receive audio.
Interestingly, the Holt site makes one thing clear: the neutral wire at the utility pole may be a few volts above ground potential, and there is
nothing you can do at the service entrance, no matter how many ground rods you may install, to reduce this potential difference. That's why the neutral should be treated the same as a hot wire. The only purpose of ground rods is to reduce on-site surges induced by nearby strikes. The ground system will do nothing to reduce destructive effects of surges that already exist on the a.c. line as it comes into the building from the utility line. But in any case, the ground system should never share any of the a.c. load current with the neutral.
