Disconnect Power When Using Generator?

The automatic transfer switch contacts can be damaged from switching power sources under load, especially larger loads like air conditioners, electric heaters, etc. There's also a remote, but very rare, possibility that a failed ATS could allow a back feed from one source to another due to welded contacts from arcing. Unplugging from shore power when running on generator power is just a reasonable safety measure. In those situations, I plug a lead light or night light into the shorepower utility outlet so I'll know when the line power is restored.

So that when the power returns you don't rely on the transfer switch to protect the generator in your RV.

So you don't back feed power back into the parks power grid.