Here is some info on GFCI's that may be your problem
If the hot and neutral wires are reversed, the circuit may still test normally, but you may not have ground-fault
protection. Verify that the wires are properly connected by testing an outlet on the circuit for correct polarity. A
GFCI should not be used with lights, freezers, refrigerators or medical equipment. A GFCI cannot be used with
appliances which are individually grounded, such as ovens or dryers
Why a GFCI should not be used with major appliances:
A Ground Fault Circuit Interrupter is supposed to be a valuable safety device. Why not use them everywhere, even on
large appliances with 3 wire plugs?
A properly grounded 3 prong outlet provides protection for both people and the appliance should a short circuit
develop between a live wireand the cabinet.
Highly inductive loads like large motors or even fluorescent lamps or fixtures on the same circuit can cause
nuisance tripping of GFCIs which needless to say is not desirable for something like a refrigerator.
Many (if not most) GFCIs also test for a grounded neutral condition where a low resistance path exists downstream
between the N and G conductors. If such a situation exists, the GFCI will trip immediately when power is applied
even with nothing connected to the protected outlets.
One: Removing GFCI protection from a receptacle in an area where the receptacle is required by Code to have GFCI
protection creates a problem. This can be called a Code violation and a hazard. The receptacle is not GFCI protected
when the RV is gone.
Two: The longer the wires, the more the "bleed" current will be. The GFCI receptacle inside an RV will see bleed
current only from the load plugged into it. The GFCI protected receptacle inside the dwelling will see the same
bleed current from the load, and will also see the bleed current from all the wiring energized by the RV power cord.
So, if you plug in a load inside the RV, into the RV's GFCI receptacle, a load that has a bleed of 3 milliamps, then
the 3 milliamps is not enough to trip the RV GFCI. Adding that 3 milliamp load bleed to, say, hypothetically, the
whole RV's bleed of 3 milliamps, then the GFCI protected receptalce inside the garage has a total of 6 (six)
milliamps bleed to ground and that GFCI will trip.
There is no technical problem. Both GFCIs are doing what they are supposed to do.
2001 Ford F-350 DRW 7.3
2011 25 RL Wildcat
former fiver 1976 Fourwinds had for 35 years