Abstract: In order to explore the influence of working pressure on the effectiveness and safety of high - pressure water mist in electrical fire fighting, the fire fighting experiment was carried out in the closed environment of 4 m× 4 m× 5 m for the same type of water mist nozzle under different spraying pressures. The results show that increasing the working pressure of the nozzle can enhance the effectiveness of the water mist to extinguish the electric fire; under different working pressure, the decrease rate of the insulation resistance is different; with the increase of working pressure, the decrease rate of the insulation resistance first decreases and then increases; when the working pressure of the nozzle exceeds a certain value, the influence of the water mist on the insulation resistance is more significant. For a specific high - pressure water mist nozzle, there is a suitable working pressure with good fire - fighting effect and small water damage.

Key words: water mist, working pressure of nozzle, electrical fire; insulation resistance