A device to measure alternating current, AC, voltage in an insulated conductor, the device comprising: a housing, wherein the housing comprises a U-shaped probe portion, including a recessed portion defined by first and second extended portions; a sensor subsystem physically coupled to the housing, wherein the sensor subsystem comprises a sensor array that includes a plurality of sensor elements (626-1 to 626-N) disposed proximate a U-shaped wall of the probe portion of the device formed by a first extended portion and a second extended portion, the sensor subsystem selectively positionable proximate the insulated conductor without galvanically contacting the insulated conductor, wherein the sensor subsystem capacitively couples with the insulated conductor; an internal ground guard which at least partially surrounds the sensor subsystem and is galvanically isolated from the sensor subsystem, the internal ground guard sized and dimensioned to shield the sensor subsystem from stray currents; a conductive reference shield which surrounds at least a portion of the housing and is galvanically insulated from the internal ground guard, the conductive reference shield sized and dimensioned to reduce currents between the internal ground guard and an external ground; a common mode reference voltage source which, in operation, generates an alternating current, AC, reference voltage having a reference frequency, the common mode reference voltage source electrically coupled between the internal ground guard and the conductive reference shield; signal conditioning circuitry that, in operation, generates a sensor current signal indicative of current conducted through the sensor subsystem; a plurality of switches, each of the plurality of switches being operative to selectively electrically couple a respective one of the plurality of sensor elements (626-1 to 626-N) to the signal conditioning circuitry; and control circuitry communicatively coupled to the plurality of switches and the signal conditioning circuitry, wherein, in operation, the control circuitry: controls the plurality of switches electrically coupled to the plurality of sensor elements to electrically couple selected ones of the plurality of sensor elements to the signal conditioning circuitry; receives one or more sensor current signals from the signal conditioning circuitry; and determines a physical characteristic of the insulated conductor based at least in part on the one or more sensor current signals. a housing, wherein the housing comprises a U-shaped probe portion, including a recessed portion defined by first and second extended portions; a sensor subsystem physically coupled to the housing, wherein the sensor subsystem comprises a sensor array that includes a plurality of sensor elements (626-1 to 626-N) disposed proximate a U-shaped wall of the probe portion of the device formed by a first extended portion and a second extended portion, the sensor subsystem selectively positionable proximate the insulated conductor without galvanically contacting the insulated conductor, wherein the sensor subsystem capacitively couples with the insulated conductor; an internal ground guard which at least partially surrounds the sensor subsystem and is galvanically isolated from the sensor subsystem, the internal ground guard sized and dimensioned to shield the sensor subsystem from stray currents; a conductive reference shield which surrounds at least a portion of the housing and is galvanically insulated from the internal ground guard, the conductive reference shield sized and dimensioned to reduce currents between the internal ground guard and an external ground; a common mode reference voltage source which, in operation, generates an alternating current, AC, reference voltage having a reference frequency, the common mode reference voltage source electrically coupled between the internal ground guard and the conductive reference shield; signal conditioning circuitry that, in operation, generates a sensor current signal indicative of current conducted through the sensor subsystem; a plurality of switches, each of the plurality of switches being operative to selectively electrically couple a respective one of the plurality of sensor elements (626-1 to 626-N) to the signal conditioning circuitry; and control circuitry communicatively coupled to the plurality of switches and the signal conditioning circuitry, wherein, in operation, the control circuitry: controls the plurality of switches electrically coupled to the plurality of sensor elements to electrically couple selected ones of the plurality of sensor elements to the signal conditioning circuitry; receives one or more sensor current signals from the signal conditioning circuitry; and determines a physical characteristic of the insulated conductor based at least in part on the one or more sensor current signals. controls the plurality of switches electrically coupled to the plurality of sensor elements to electrically couple selected ones of the plurality of sensor elements to the signal conditioning circuitry; receives one or more sensor current signals from the signal conditioning circuitry; and determines a physical characteristic of the insulated conductor based at least in part on the one or more sensor current signals.