Meanwhile, where is the all so necessary safety ground.
Earth ground rod is not a safety ground.

w_tom wrote:
The same switch that connects generator to water heater must
also disconnect AC mains from water heater. Switch must be
'break before make' type. It does not matter how many times
you say "it is off". Humans have a bad tendency to always
make the exception occur. A design must be human proof.

Design must be 'not mechanically possible' to ever connect
generator until heater has been disconnected from AC mains. ...