to clarify the cable is running along side high voltage wiring, or the board is operating at a higher voltage than what the connector is at, as each required a different approach,
equally what voltage levels, 2KV is much easier than 33KV,
as a starting though if the board is at a higher potential, figure out your direction and simply use opto-couplers with a pullup provided by whatever it connects to,
if it has to run along side some very high voltages and you cannot find wiring with high enough insulation you can use toslink optic fiber to create a completly optical path to the connector, once again it would need power on the other side for the photo-transistors,