An impedance monitoring circuit for an electrosurgical generator is disclosed. The monitoring circuit includes an isolation transformer coupled to at least one of an active terminal and a return terminal of an electrosurgical generator, wherein the isolation transformer includes a primary winding coupled to a reference resistor and a secondary winding coupled to a load. The monitoring circuit also includes a driver configured to transmit a sensor signal to the reference resistor and the load, a primary converter coupled to the reference resistor and the load and configured to detect a primary converted signal as a function of the sensor signal passing through the reference resistor and the load. The monitoring circuit further includes a secondary converter coupled to the driver and configured to detect a secondary converted signal as a function of the sensor signal prior to passing through the reference resistor and the load and a controller configured to determine a fault condition based on the primary and secondary converted signals.
