WHY Does my Voltage Indicator Beep During Safe Isolation In this video we explain why your voltage indicator could beep (or buzz) during the safe isolation process. Whilst carrying out the safe isolation process we proved the circuit was isolated but got continuity between CPC and neutral, neutral and switching line plus CPC and switching line. Using a wiring diagram and our knowledge of TN-S and TN-C-S earthing arrangements we can plot the continuity path that is causing our voltage indicator t