Amateur electricians can get away with some mistakes at home that can be lethal when made while wiring an RV. Why? A recreational vehicle has the hot, neutral, and protective ground connections just like your home. But unlike your home, the RV has no permanent ground connection. When plugged into a generator, the RV and generator will often be isolated from ground, affording no protection from shock hazards. A proper generator setup connects ground and neutral at the generator and bonds them to a ground rod or other low-resistance connection to a real earth ground. But we know that most generator users have never done anything like that.
At an RV park or anywhere you plug your RV into electrical service, you can lose your proper protective ground connection because the ground pin breaks off of your RV’s plug, or a mis-wiring in your RV or the park’s wiring breaks the ground connection. But the park’s electrical system still has neutral and ground connected, while your RV doesn’t. The problem with this comes if some failure in your RV then causes a connection between the hot wire and what should be your ground connection. Rather than immediately blowing the circuit breaker, as it would in your home or a correctly-grounded RV, this situation creates “hot skin”. The metal shell of your RV is connected to lethal electric power. A person who walks up to your RV and touches it can then become the path of all of that power to ground, and can be electrocuted simply by brushing against your RV. Several people have died or have been severely injured from such situations. Children are especialy vulnerable. Imagine a child standing barefoot in wet grass and touching your RV. In a hot-skin situation, that child might die.
There are a few things you can do to protect against this. First, fit your RV with GFI or dual-function (GFI+AFCI) circuit breakers on all of the branch circuits, if it presently has the old non-GFI breakers. Second, use a “Power Management” device that protects you from mis-wiring, like those sold by Progressive Industries (http://www.progressiveindustries.net/). The right device will be listed to provide “Reverse Polarity Protection” and
“Open Ground Protection”. Not just surge protection! A surge protector alone won’t in general protect from grounding problems.
You’ll spend a few hundred dollars adding GFI breakers and a power-management system to your RV. But their protection from situations that can otherwise kill an innocent person is priceless.
Power management systems are more picky about the power provided to them than your RV or circuit breakers would be without them. They’ll insist on an adapter plug that provides a neutral-to-ground connection at your generator before they allow its power on-board. But they will protect from most grounding mistakes. Once in a while, they’ll refuse to connect power from a trailer park source that is mis-wired. You’ll need to take that up with the park when that happens.
NEVER wire any device to the ground wire when it should be connected to the neutral wire. Yes, it will appear to work correctly, but it can create hot skin if your RV ever does not get a proper ground connection at the plug.
Amateur electricians are often confused by grounding. I had one argue that a bulb connected from hot to ground could not create “hot skin”. He tested it himself and when he disconnected the ground pin, the bulb just went out! He just could not conceive that a bulb that had gone out could still conduct electricity if someone completed the circuit from his trailer to ground with their body. There was no way I could convince him. This guy may kill some innocent person someday with his incorrect wiring. Don’t be like him.