I got into an interesting conversation via email with a customer about use of BNC connectors to carry high voltage. The HIPOT tester was already out so off I went. The Hi Pot tester used goes to 4000 volts RMS. At anything less that 2200 VRMS there is no sign of leakage. At somewhere above 2400-2500 volts breakdown occurs. This is with the connector un-mated. I then tried plugging in mate without cable attached. The breakdown voltage actually increased. Here’s a photo of the connector arcing over at 2500 VRMS
A couple of things… High voltage is dangerous. Don’t play with HV when you are tired or distracted Do not Hi Pot and let the DUT arc over for a long period of time.It produces ozone This kind of testing is potentially destructive to the DUT. With repeated testing the breakdown voltage decreased.