Newbie question - plugging into home elec

[Gary RVRoamer]

I suspect it may have something to do with the size of the coach electrical system.

Not at all. If your coach trips a GFCI, it has a ground fault. That's an indication of electrical system defect and not a "normal" condition for any RV. It's a safety issue - the electrical system is not protecting you from shocks if something goes wrong. Some fairly common RV electrical problems that trip GFCIs are high resistance faults in the fridge heater element (RV fridges only - not residentials) or improperly grounded inverters or converters.

[OlYeller]

You need to be careful in just plugging into a garage or outdoor outlet. Most likely they will not only be on a 15A circuit, but the wiring to it will most likely be 14GA. If the amp draw it too great it will not only overheat the cable to the RV, it could damage the wiring dangerously inside the walls of your home. The proper solution is to have a 30 or 50A outlet installed with the correct gauge wire to it from the breaker box off a matching amperage beaker.

I installed a 30A outlet in my garage but I can only run the converter and fridge on it. My AC draws too much and the wiring to it is 14GA. I will be wiring an correct setup soon.

[alvo]

You can look up the specs for your AC unit and see what you need. Mine is 14.9 amps max and will start up connected to a 15 amp circuit. It trips the breaker when any other load is added, so I never use it.

The best solution is to install a 30 amp circuit to use, which should be enough to run the AC and leave you about 15 amps for other things, including the refrigerator which should use anywhere near 15 amps by itself (check manufacturer specs for requirements).

For me, on a 15 amp circuit, my refrigerator runs, my electric water heater works, and I can use the microwave at the same time and still have enough power for the computer, television, wi-fi network, lights, and misc. other things.