Hello good people?

When looking at information for Co2 extinguishers and their safe use on electrics, most information states "Safe for Low and High Voltage" but exactly how high ? is it unlimited because it`s a gas or is there a ceiling, Ta 

Powder and gaseous extinguishing agents are generally accepted as non conductive on all voltages - liquid based agents have also been tested to high voltage (35,000V) but in practice are marked for up to 1000V to give safety margin.