An improved circuit and method for detecting dielectric breakdown and ground fault conditions is provided. The circuitry and method of the present invention include taking a continuous voltage reading of the high voltage battery and sampling the continuous voltage reading of the high voltage battery at a fixed time interval. The circuitry and method calculate a change in the continuous voltage reading of the high voltage battery over the change in time and repeatedly calculate an optimum fixed time interval and an optimum change in voltage over time. Storage of the optimum fixed time interval and optimum change in voltage over time provides for repeatedly comparing the optimum change in voltage over the fixed time interval to the constant voltage of the high voltage battery to calculate the resistance of the dielectric breakdown fault. The calculation of the resistance of the dielectric breakdown fault is carried out independently of the capacitance of the electric circuit. The circuit and method provide adjustment of the optimum fixed time interval to improve the speed of the comparison of the optimum change in voltage over time to the constant voltage of the high voltage battery to calculate the resistance of the dielectric breakdown fault.