Important - check this every time you set up

Anytime you measure more than 2 or 3 volts AC between the chassis of your RV and the earth, there's cause for concern. That's because you've lost the connection between the chassis (skin) of the RV and the earth-grounding point at the service panel. Once that happens, then all it needs for a chassis voltage to occur is a leakage current between the 120-volt line and the chassis. Could be a short in a wire. Could be a pinhole leak in a hot water heater element. Could be internal leakage in a microwave or inverter transformer. Once those two things happen, then all it takes is for someone to be standing on wet soil and touch the RV with a damp hand. That's when death by electrocution is a real possibility.

So anytime you measure a voltage or feel a shock it's time to immediately find and correct the cause. Please don't become a statistic.

My 2015 178 tests hot with a Fluke Meter when plugged into my 110 house circuit.

This is a very pertinent post. I spent many years in the military, One thing that was a constant issue was troops setting up gear in the field and not using the ground rods with the generator power source. Many troops were injured. An ungrounded power source is a concern. Kudos to this discussion.

+2. Thanks Mike!

Glad I was able to help. Just about every electrician and technician has a Non Contact Voltage Tester, but most of them don't realize how great they are at finding a hot-chassis condition from a broken ground connection, many times caused by a mis-wired or broken extension cord. 

Let's play safe out there...