0kelseymhBest Answer 9 years ago ReplyUpvoteWhat country are you in? In the U.S., wall voltage is 117 VAC (rms), at 60 Hz. In Europe and Japan, it's 220 VAC at 50 Hz. USB output is 5 VDC, with a maximum current of a few hundred mA. If you don't know what you're trying to power, choosing the wrong option will do a lot of damage.