Greywolf 2018 Electric Water Heater wiring

Not sure what you mean by "electric side burning through thermostats". Either you turned it on empty like Bid Time suggested, which can come from thinking you are de-winterized and you aren't, or there is a loose, open, or corroded connection or ground issues. You won't find a wiring diagram for just about every RV in existence. And as Bid time stated, provide the make and model of your water heater and be more descriptive of your issue thinking about the root cause. And not sure what it means when you say "wiring needs to be changed". I can see replacing damaged wired but changing wire?