A wearable cardioverter defibrillator (WCD) system (101) is described that includes patient parameter electrodes (114, 118), such as ECG electrodes, that are at least substantially electrically isolated from other circuits of the WCD system. The WCD system includes a power source, an energy storage module and a processor, each connected to a first circuit ground. A patient parameter sense port, such as an ECG port, is coupled to the patient. A measurement circuit is configured to render a physiological input from the sensed patient parameter received at the patient parameter sense port and includes an isolating circuit that electrically isolates the patient parameter sense port from the first circuit ground.
