I'm building a 4500W/5700W RIMS/BK system using one of PJ's wiring setups and am wondering what to do for the main supply chord from the 50A GFCI spa panel to my control box. PJ's diagram uses 4-wire. I bought some 6 AWG SJOOW wire from ebrewsupply, but haven't yet found a 4-wire plug rated above 30A yet. Any advice appreciated.