I want to make an adaptor to connect my generator to my 220 ac air compressor. I purchased a three conductor 12 AWG wire cable three feet long, a L14-30P, a 6-20R. I connected the cable to the 6-20R green to grd. white and black to the two flat receptacles. I have connected green to the G terminal on the L14-30P. Where do I connect the white and black? I have X, W, and Y.