> On average the signal over 24 hours will equal about 24 hours so you can keep time with it, but as the load changes on the grid it will actually slow down an

> On average the signal over 24 hours will equal about 24 hours so you can keep time with it, but as the load changes on the grid it will actually slow down and then speed back up when people turn off their devices at night. Yes, the load changes the frequency over the course of a day. In Great-Britain there's even a special peak after the afternoon TV shows finishes and people start turning on their electric kettles to prepare tea. http://www.bbc.co.uk/britainfromabove/stories/people/teatimebritain.shtml http://www.bbc.co.uk/britainfromabove/stories/people/teatime... In fact, the exact frequency of the power grid can be used to identify precisely the time of the day! http://en.wikipedia.org/wiki/Electrical_network_frequency_analysis http://en.wikipedia.org/wiki/Electrical_network_frequency_an...