Steve wrote in :

50A! I only have 20A wiring but then it is for 240V. Does that mean you
don't think that the voltage spike will cause a problem to the inverter
when the mains is unplugged?


Proper transfer equipment OPENS the circuit between the time it disconnects
from one AC source and connects to the other. There are no spikes. Break
before make it's called.

You'll notice a little dark period between when the AC line disconnects and
the genset connects when the transfer switch is thrown, automatic or
manual.