HALP! Getting electrical shocked from bus 110V electricity shocking shock

[Len Silva]

There should be NO leakage with the possible exception of capacitors as mentioned.  You should be able to measure with an ohmmeter between the neutral and ground on the main plug and get infinity.  Between hot and ground you may see a small kick in the meter (analog) as the capacitors charge up but it should also rise to infinity. Only between hot and neutral should you get a resistance reading at all, that is measuring across the various loads that may be connected.

I prefer an older analog meter for these tests but a digital will work.

[eddieboy]

Your problem could be totally unrelated to your electrical system, other than needing to have the ground pin connected. 
Try to follow this:  every Labor Day I set up a food trailer in the park for the American Legion.  We have about a 30 amp supply directly out of the distribution box.  The trailer was wired by me, so I know it is all correct. (no attitude with that statement).  As other vendors started hooking into local outlets for coffee and hot dog machines, one of our members touched the trailer and got a shock. (he's ok) I went through everything I could possibly think of and then ran an idea by the local electrician.  As more people were connecting in, the voltage would shift on one leg to 140 volts and the other leg would go to about 70 or 80. We also tried adding a ground rod and it do not help.  My suspicion was correct, the neutral to the main distribution box was weak and our electrical system was completing the circuit to everybody elses equipment via the ground.  We ran a temporary neutral for the weekend and all was well.
On another occaision, I had a co-worker phone me that her son was getting shocked standing in the garage touching the rail for the overhead door. He was in bare feet.  I determined that the garage neutral was bad and needed to be replaced.  It was at this time in my life that I also discovered that CONCRETE IS CONDUCTIVE.  I was able to touch one lead of my meter to the rail and the other to the concrete and I read over 90 volts.
When you first set up camp, take a meter with you and stick one end in the ground and the other end on the frame of your bus.  Look for voltage.  If any is present, disconnect your shore line before it kills you!!!
Happy hunting.
Ed