Originally Posted by roach711
Definitely ground the AC panel to the skin. If you don't and one of your 120v hot wires gets loose and touches your bus body the whole body will be energized and the breakers in your power panel won't trip since they have no idea there's a problem in the wiring. Ground the body and now your breakers will trip when there's a short like they're supposed to.
Excellent summary of the risks. IMHO the main purpose for thoroughly bonding all the metallic (electrically conductive) building components together is exactly as roach711 described. If/when an electrical fault develops, we want
the circuit breaker, GFCI, AFCI, fuse, etc to trip promptly. Oftentimes there isn't any immediate injury or damage when a fault develops. Think of electrocutions in marinas, loose connections that arc and heat for some time before igniting a fire. The fault exists for some time before anything serious happens. If we install the right kind of protection device we may detect a fault and interrupt the electricity before there's any injury or significant damage.
Originally Posted by milkmania
When I read that article last night about "hot skin" on a bus, it really made me wonder about generator electricity! I know if my bus electrical is proper, it'll pick up the earth ground from the shore electrical pole at an RV campground, but what about generated electricity and rubber bus tires?
Another member wrote about generator ground bonding and suggested that generators usually are bonded. I trust his/her experience, but mine has been the opposite: I have two Honda inverter generators (different models) and previously had a Generac open-frame. None had built-in bonding, and I actually have caused some damage through my own inattentiveness in wiring combined with the generator's lack of built-in bonding.
I'm not sure the insulation factor of the tires comes into play with a generator (or inverter). If the generator/inverter is built-in then the world beyond the bus wheels is arguably not part of the picture. If the generator is sitting in the grass out behind the bus, then.. maybe. We could try to cook up some scenarios. If the generator did not have a bond between its chassis and neutral, and if it had some internal fault so that the hot side became connected to its chassis, no breaker would trip on the generator. Yet its chassis would be "hot" and, sitting on the earth/grass, I guess technically an inverse hot-skin condition develops because the bus skin is bonded to neutral through wire while the ground below is hot through the soil, the generator frame sitting on the soil, and the internal fault in the generator.
IIRC ground rods for portable generators are required by OSHA for movie productions on-location outdoors, for example. I'm struggling to construct a scenario in which the ground rod is an important part of the safety of the system though.