Convert 3 Prong Dryer Plug To 4

200813the 4 prong cord cap will plug into to the 4 prong receptacleow coming out of the cord cap you have the scr cable, for "x" feet, then going into a female 3 prong receptacle female, in which the welder would plug intohe difference between a 4prong receptacle and a 3prong.