I have a 240V 30A dryer outlet in my garage that I am not using as our dryer is gas. I wanted to covert the plug to a 20A 240V. The plug is the older type NEMA 10-30 240/120 combo which has no ground but 2 hots and neutral. Is converting as simple as pulling the 30A breaker and getting a double pole 20A, connect the two hots but then take neutral and move it to ground? Want to replace with a NEMA 6-20.