I have a 240 volt air compressor with a 3/4hp 3phase motor on it. My questions are can I put a 4 prong plug on the compressor and use that outlet? The compressor has 4 wire comming out with no plug is how I bought it. Or do I have to use 3 prong 240 without the 120 line. I'm going to be using a phase converter to use residential power. Only reason I bought a 3 phase is because I got a deal of a lifetime on it and could not pass on it. I'm not asking to wire up a new receptical just needing to know if I use 4 or 3 prong because I have a 4 prong outlet already hooked up I'm just going to make a 240 exstention cord to run off that untill I run a whole new line for perm install thanks for the help!