If your neutrals are tied to ground, then the very second you turn on the multi, it (the multi) shorts the neural tied to it to ground! That will trip your GFCI on your pedestal/garage or whatever sources the input 110/120v AC to your RV.
Look up GROUND RELAY on this site.
I hope that's what your asking.
ps...if the Multi didn't do this, then a person could get the 120v shuffle if it shorted in your wiring....so TECHNICALLY, its a good thing. But a pita to wire it so it doesn't.
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