I have the SP-135, which is a 110 unit. For sheetmetal, it is perfect! For thicker metals, say 1/4" up to 3/8", I can make it work. I think it is rated at 20 Amps. If you run long cycles on a standard outlet (which is typically 15 A), you will trip the breaker, especially if other stuff is running on that circuit. What I did was install a dedicated 20A outlet and I also picked up a very heavy extension cord. No problems running long cycles. If you keep the cycles short, a standard circuit will do just fine. The advantage of going with a 110 unit is that you can take it with you wherever you go without worrying about power. I've used mine on the back porch and stuff like that. Of course, the 220 units are smokin' awesome, especially if you do heavier stuff, but they are more expensive, physically larger, and definately not as portable.