Tom's comment about the neutral got me to considering the possibilities. While I don't agree that the EMS has any bearing on tripping how the neutral is handled in the distribution panel sure does. Just remember that for a GFCI not to trip, ALL the current that flows through the hot wire MUST return through the neutral. Now if an owner or a manufacturer bonded the neutral to the ground in the distribution panel that GFCI will trip every time. Most distribution boxes allow for this configuration and it is easy to do. Some even have a screw that is positioned between the neutral and ground buss, and just screwing it in bonds the two systems together - something you do not want to do on an RV. Here is a bit of an explanation from a primer on RV electricity.
First thing first: The neutral and ground in an RV electrical loadcenter are NOT to be bonded together.
The RV chassis is isolated from ground by definition. Metal leveling jacks and such, mounted on the vehicle frame do not make an adequate ground contact. Therefore, in an RV, you always want to have a "floating" neutral, where the neutral and vehicle ground never come together. When you bond the neutral and ground together in an RV, you have a "floating" ground (rather than neutral) and this will result in nutty things happening.
My comment - and one of the "nutty" things will be a GFCI tripping if you try to power the RV through one. So check it out if your coach trips Tom's breaker. Mine did not as I don't remember plugging it in there
