A calibration system operative to calibrate a voltage measurement device , wherein the voltage measurement device is configured to generate a reference current signal (I R ) and to sense the reference current signal in a conductor under test via a voltage measurement device sensor , the calibration system comprising: a controllable calibration voltage source configured to selectively output a voltage in a calibration conductor ; and control circuitry communicatively coupleable to the calibration voltage source and the voltage measurement device, wherein the control circuitry, is configured, for each calibration voltage of a plurality of calibration voltages: to control the calibration voltage source to output the calibration voltage in the calibration conductor; to obtain a plurality of calibration points associated with the calibration voltage, each of the calibration points comprising: a reference current signal data point obtained from the voltage measurement device that is indicative of the reference current signal that is measured by the voltage measurement device via the voltage measurement device sensor when the calibration voltage source outputs the calibration voltage in the calibration conductor; and a calibration factor indicative of a ratio of the calibration voltage to a measured output voltage data point obtained from the voltage measurement device that is determined by the voltage measurement device based at least in part on the reference current signal data point; to determine calibration data for the voltage measurement device based on the obtained plurality of calibration points, the calibration data dependent on the reference current signal measured by the voltage measurement device and the plurality of calibration voltages; and to store the calibration data on at least one nontransitory processor-readable storage medium associated with the voltage measurement device for use by the voltage measurement device during subsequent operation of the voltage measurement device. to control the calibration voltage source to output the calibration voltage in the calibration conductor; to obtain a plurality of calibration points associated with the calibration voltage, a reference current signal data point obtained from the voltage measurement device that is indicative of the reference current signal that is measured by the voltage measurement device via the voltage measurement device sensor when the calibration voltage source outputs the calibration voltage in the calibration conductor; and a calibration factor indicative of a ratio of the calibration voltage to a measured output voltage data point obtained from the voltage measurement device that is determined by the voltage measurement device based at least in part on the reference current signal data point; to determine calibration data for the voltage measurement device based on the obtained plurality of calibration points, the calibration data dependent on the reference current signal measured by the voltage measurement device and the plurality of calibration voltages; and to store the calibration data on at least one nontransitory processor-readable storage medium associated with the voltage measurement device for use by the voltage measurement device during subsequent operation of the voltage measurement device. <EOS>