Originally Posted by ajk
There is no need to do that, the Amiga doesn't have a concept of regions. The difference between PAL and NTSC is simply a difference in the TV standard used (which in turn stems from the difference in mains frequency). As long as your monitor doesn't mind, you can switch between PAL and NTSC as you wish.
However, if you are using real hardware you need the correct sort of power supply. As you are talking about a PAL Amiga and you are in the USA, then you should look into a stepup convertor.
UK power supply = 230V, 15AMPS @ 50Hz
US power supply = 110V, (don't know ampage) @ 60Hz
Power supply frequencies, on Wikipedia here