They're 110/120, so there's no problem with either 2 or 3 prong. The third prong is just a ground. However, if your appliance is a 3 prong and the wall plug is only a 2 prong, you need an adapter. Believe that's why the question was asked. We always carry a 2 to 3 prong adapter just in case. You can pick them up at any hardware store for less than a buck.
