Patent ID: 8575942

Claim:
A hand held contact voltage source detection apparatus for identification of hazardous contact voltages on energized objects or surfaces, comprising: (a) an electric field sensor structured to sense an electric field; (b) an amplifier electrically connected to the electric field sensor to amplify electric signals from the electric field sensor; (c) a signal conditioning circuit adapted to process the amplified electric signals and form time-coordinated signals, wherein the time-coordinated signals formed by the signal conditioning circuit are a third derivative (f0′″) signal of the amplified electric field signal, a third harmonic frequency to fundamental frequency comparison signal (H3/f0) from the amplified electric field signal, and a signal formed from the signal representing the percent total harmonic distortion (% THD) of the fundamental frequency of the amplified electric field signal; and (d) a signal processor adapted to evaluate the time-coordinated signals and provide a user with a status of a contact voltage source by activating an appropriate status indicator.