Progressive Dynamics #PDYPD52V 240 VAC 50 AMP Auto Transfer Switch PD52VProtect your RV's electrical system from costly damage with the Progressive Dynamics PD52V 50 Amp Automatic Transfer Switch. This 240V 50A unit monitors your power sources and automatically prevents shore power and generator power from feeding the AC distribution panel simultaneously the kind of failure that fries breaker panels, damages appliances, and creates fire hazards. A small unit that prevents a very expensive problem. Why an Automatic