A system and device for measuring voltage in a conductor having a voltage provides a first electrode surrounding and spaced from the conductor, and a second electrode surrounding and spaced from both the conductor and the first electrode such that there is no contact between the conductor and the electrodes or between the first and second electrodes. The first electrode is connected to a first input of a differential amplifier circuit and the second electrode is connected to the other input of the differential amplifier circuit. The output of the differential amplifier circuit provides a voltage signal in proportion to the voltage of the conductor, thus providing a non-contact means for measuring the voltage of a conductor without requiring a connection to ground while simultaneously providing a high level of rejection of external interference.