When switching off the unit and only having surge protection and if I read this right 220v went into your camper...you might want to ck your cords connections inside the plug..this had happened to me! (reason I bought the EMS from Progressive) I traced the problem to my cords plug to the camper/ taking my cords plug apart found the neutral wire sliding in and out its neutral prong slot,the scerew was lose. so if cord was moved while plugged in trouble happened..tighten the screw alls fixed plus 2 TV's 2 VCR's and one radio all from 240v surge and thats why i bought my progressive hi/low voltage protection..