GFIC G-N fault at converter

I agree with ScottG. Let me amplify a bit. In simple terms, a GFI measures the current flow in the hot wire and the neutral wire. If the current in each wire is not exactly the same the GFI will open the circuit. Why would the current be different in the hot wire and the neutral wire? Because some current is flowing from the hot wire to the ground wire. As long as the ground wire is connectec to an earth ground there is no safety problem BUT many times a second problem happens, the ground wire becomes disconnected. When that happens the so called ground becomes a live wire. Anyone touching the live wire and a real ground may get a deadly shock.