The 'more metric' 50Hz made me smile. The Wikipedia article on the history of these frequency choices suggests it was increased from 40Hz to 50Hz to stop visibl

The 'more metric' 50Hz made me smile. The Wikipedia article on the history of these frequency choices suggests it was increased from 40Hz to 50Hz to stop visible flickering of lamps. It's an entertaining read: http://en.wikipedia.org/wiki/Utility_frequency#History http://en.wikipedia.org/wiki/Utility_frequency#History