Some people say it does with certain devices but I've never had anything I've run into. The American outlets have been used as bi-directional in most instances. (With 2 prong). If they had a ground then you can only go in one way. But that said... Obviously a cord without a ground can still plug into an outlet that has the ground set up. If the device wants the current to go in a certain direction they use one with a slightly larger prong on one side, but if you pick up any phone charger in America, you can plug it into any outlet any direction.