Flying a 81 M20J around and encountered visible moisture below 10C. Put pitot heat on and received an instantaneous low volts warning, volts dropped on all eye-brow lights and the pitot-heat switch went to the 'off' position at the same time. Switched the 'Pitot Heat' and 'Strobe' Klixon switches since they are the same amps and same issue. Possibly a bad ground? Anyone experience this in flight? Any ideas?  Currently at Spokane far away from home station.