Never allow 110 AC to back feed an inverter thru the inverter 110 AC outlets as all I've seen will smoke for a second if it even takes that long and then you'll get to but a new inverter. Only happened to me once before I learned the hard way.
After that bad experience back in the very early 1990's. When we got back home I went to an electrical supply place locally and bought 3 little enclosed in clear plastic 10 amp DPDT (Double Pole Double Throw) relays having 6 little connections lugs that are roughly 1" wide, 1-1/2" long, and about 3/4" thick in size. They can vary in enclosed plastic case size and/or amp capacity as needed or wanted but all do the same task. It's just an auto switching relay and not expensive. Mine cost $10.50 each and have purchased 4 more recently also for other things/uses. The joys of being a retired engineer!
Also a blue shallow electrical box, a standard duplex outlet receptacle, and a plastic 2 outlet receptacle cover to enclose the outlet box, also very cheap at around $3 total. Mount the new box and covered outlet in a hidden location like inside a cabinet or behind a removable access cover or as I do, right next to or near an OEM outlet clearly labeled "110 AC shorepower/inverter ____ amp only"
I use a simple off the shelf 10 amp mini fuse wired on the shore power hot side incoming black wire as the OEM circuit is 15 amp min. After the fuse the wire goes to the relay's solenoid activation lug so the shore power is only going thru to the duplex outlet when the shore power has current because the solenoid had moved the contacts to the shorepower contacts side inside the relay only. When there's no shore power, the contacts instantly move back to the inverter AC powered pass thru relay contacts.
Thus, both power sources cannot be connected at the same time and both can be safely connected to the relay at the same time. You won't even nor can you tell the relay is even there as it auto and instantly switches from shore power to inverter should the shore power fail and back when the shore power comes back on.
I also did this for the RV microwave for shore power/inverter auto switch over AC outlets. Another in the bedroom, in the bathroom vanity also and one in the kitchen slideout for laptop etc use and charging while using. Only limited by your imagination. We always have 110 AC powered outlets inside the RV anytime anywhere as needed without starting the generator and it's so quiet for making coffee and toast etc in the morning even if right next to another RV with people sleeping inside.
It's not a difficult thing to do and works great and is very reliable and so many uses.
Another way is using 3 way switches for an AC outlet. Center is off, down connects power from one source, and up connects power for a different source. Only requires a flip of the switch. isolates both inverter and shore power AC power connected until you flip the switch up or down as desired. Can all be in one square electrical standard box outlet or in separate single box outlets or just adding to an existing duplex outlet area. Must select the power source as it's not auto switching for maybe the real lazy.
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