Why isn't our electricity a higher frequency?

[rjain]

You can reverse the polarity with american style plugs, too... Three-pronged plugs make it hardest to do that, but two prongs of different sizes do it for both flat and round plugs.

 

[f95toli]

It is impossible to reverse polarity on the european style connectors because the polarity does not matter. On the round connectors there is no pin for ground. You can turn the connector any way you want.