Twist Lock Plug Wiring Diagram 4 Way | Parts Illustration Twist lock 50 rv plug wiring diagram best wiring library 50 rv power cord wiring diagram lovely 50 wiring diagram reference twist lock. 5 7 mercruiser starter wiring diagram wiring diagrams • intended 5 7 mercruiser starter wiring diagram wiring diagrams • intended for mercruiser ignition wiring diagram. 4 way plug wiring diagram wiring How to Wire a 4-Prong 240-Volt Twist-Lock Plug | Hunker How to Wire a 4-Prong 240-Volt Twist-Lock Plug. A four-prong 240-volt twist-lock plug is one that is approved by the National Electrical Manufacturers Association (NEMA) for production and sale in the United States. A four-prong plug has two hot wires, a neutral wire and a grounding wire. The plug is designed to lock onto a matching receptacle by..