A power supply device may include a connector configured to electrically couple the power supply device to a conductor of the underground power lines; a voltage divider configured to receive an input voltage from the conductor, the voltage divider comprising a capacitor and divider voltage control electronics in series with the capacitor; and, a surge resistor in series with the capacitor and configured to provide impulse protection from surge events. The divider voltage control electronics may be configured to regulate an output voltage of the voltage divider to support variable loads on the voltage divider.