I plug mine into a surge protector, but, when I am done sewing for the day I put the needle down, the pressure foot down and unplug my machine. I had read on here at one time that you can never be 100% sure that it will always off. So I asked my Son the electrician about it. He to said that if there should be a lightening strike, that it could still ruin my machine although I had the surge protector plugged in.
FYI: I also try to always remember to unplug my iron at the end of the day. I read on here that someone had an iron fire before. Although it probably will never happen why take the chance. That's my motto!!!