Not sure I understand the question...
This is a typical wiring for the Camp site Pedestal providing both 50AMP and 30AMP service
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This is a typical RV 50AMP Distribution. This give you two zones of 120VAC breakers. Note shown here one A/C unit is in zone one and the other A/C if installed is in zone two. All of the breakers here are rated for what they are to provide 120VAC protection for.
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This is a typical RV 30AMP Distribution. This is only for a single zone of 120VAC breakers. Again each breaker used here are rated for the what they are to provide 120VAC prptection for.
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If you have a 20AMP 120VAc circuit breaker installed it will trip when that particular circuit is drawing more than 20AMPs and will not trip the MAIN 50AMP or 30AMP circuit breaker.
You can plug a RV 30AMP system in the 50AMP receptacle using the proper RV30A to 50AMP Adapter and the 20AMP circuit breaker discussed above will also only trip when you have exceeded the 20AMPs current. The main 30AMP breaker for your 30AMP distribution panel will not trip.
just my thoughts
Roy Ken