There used to be a company PSRV (Power Solutions RV)..
Now they did it at the generator junction box.. Many 30 amp RV's have a dedicated line at the generator that runs the Rear A/C but .. Any spot along the DEDICATED line to the rear A/C (any wire that goes NO PLACE ELSE.
Mine is a 50 amp RV so I did it at the breaker box.
Orignial
Breaker------- Rear AC (mine)
30 amp
ORiginal Breaker----Transfer switch and generator----A/C
Modified
Mine---Breaker-------Outlet-Plug-----A/C
Yours
Breaker----Switch/generator----Outlet--Plug-20amp breaker---a/C
(I choose to trust the park breakers)
