I don't know if you have a 30 or 50 amp system, but it sounds like you have a bad neutral and the coach is not properly grounded, hence the electrical shock. I think this is serious enough that the problem should be fixed before using the coach again. It could be in the coach or in the power supply from the supply socket. When I bought my coach earlier this year, the paperwork included a handout on 120 volt coach electrical service from a seminar given at the January, 2003 Newell Rally in Palm Springs, California. I quote a few paragraphs from the handout that explains the issue in laymans terms (and boy am I a layman with electricity):
A 30-amp RV plug contains a 'hot' supply wire that brings electrical flow into the coach and a neutral output wire (also called a ground or common) that returns the flow to the power plant. If the 'hot" input wire breaks, the incoming power stops and you are without power. If the 'neutral' return wire breaks, the electrons continue flowing into the coach, with no place to go. Your RV is now 'filled' with electrons and becuase it sits on insulating rubber tires, the electrons just sit there looking for an easy pathway home.
The earth is a pretty good conductor and it is huge, so it makes a great return path for electrons. "Ground" in the power distribution grid is literally "the ground" that's all around you when you are walking outside. It is the dirt, rocks, groundwater, etc., of the earth. Because electrons are always seeking a path to ground it is important that you stay ouf of their path. For example, Joe Camper plugs his RV into an RV park pedestal having a faulty neutral and his RV becomes 'charged' with electrons with no place to go. The electrons just sit there like vultures waiting for the kill. Poor Joe returns to his coach after a late night rain shower, inserts the key into the door, and gets the shock of a lifetime.
To reduce deadly grounding accidents, the building code requires the addition of a safety wire and a grounded neutral. The safety wire is attached to a long rod driven deep into the ground. The neutral and safety wire in a residential service are bonded to the grounding rod in the home's main curcuit breaker panel. Because RV's sit on insulating tires, and most RVer's refuse to pound a metals rod deep into the ground every time they stop, both the safety wire and the neutral wire are kept separate until reaching the RV parks electrical system via your service cord. Once inside the park pedestal they are bonded together and attached to a grounding rod. This is called a floating neutral, and it places you at the mercy of the RV parks electrical system. If the RV park service pedestal has a faulty ground, then your coach has a faulty ground. If the service box is wired backwards, (reverse polarity) then your coach system will be backwards.
On my coach (2000) Newell has provided a warning light that indicates if the polarity is wrong. I cannot remember if there is a similar warning light indicating an ungrounded neutral. The same handout describes the procedure for checking a 50 amp park pedestal for proper wiring using a multi-meter.
As you face the [50 amp] receptacle at the campground pedestal, you'll see three vertical, flat slots. The outer (left and rigth vertical slots) are 120 VAC 'hot' outlets. The inner (center/lower) flat, vertical slot is the neutral. The round hole near the top is the ground.
Set the multi-meter for AC volts and go to the higher range (usually 750 volts). Put one probe in the left hot slot and one probe in the right hot slot. You should read about 240 VAC.
Next, move one 'hot' probe to the neutral (center) slot. You should read about 120 VAC. Move the hot probe to the other hot slot. You should again read about 120.
Next, move probe from neutral slot to round ground hold. You should again read about 120 VAC. Move probe from first hot slot to other hot slot and again should read about 120 VAC. The receptacle is OK.