The easy answer is, it depends! Example, my table saw can be ran on 120 or 240, but it depends on how you have the motor set up. I know if i set it up for 110 and I plug it into a 220 outlet, I will be looking for a new table saw. If the motor is set up for 220 and I plug it into 110, I doubt it will hurt the motor, but I also doubt that it will function correctly. In essence, your motor, your plug, your receptacle and your power source, all have to agree. That is why there are so many different configurations of plugs. With that said, I have done some wierd plug hook ups. Some of my plugs I like to have turn and twist so they stay in, but most of these are 220v. So I have a receptacle that is wired for 110 and has a 220 receptacle. The plug I have is a 220 plug, but it is all wired for 110. why would you do that you ask? I live 2 hours from the nearesr supplier and I had the 220 receptacle and the 220 twist plug and I need it done today. Now if I die and someone comes and plugs a 220 plug in there thinking they are going to operate a 220 appliance, good luck. Now, coversely, I would not hook up a 220 line to a 110 outlet as that could do some damage.