So, the Elcon charger I'm using has just two wires for power, no center leg. So, I can cut the 20amp 220v outlet off and use a welding style 50amp plug and plug it in where I plug my welder. However, the juice box that just arrived has three prongs - and all of my outlets just have two wires and ground. Are they using the center leg to get 110v in the Juice Box? Am i going to have to pull a whole new cable into the outlet to make the Juice Box work?