Air insulated Load-Break Switch (LBS) was selected to perform research, described in this paper. Examined switch was equipped with effective arc extinguishing systems designed to interrupt a load currents ranged of hundreds of amperes at Medium Voltage (MV). For arc quenching efficiency enhancement switch features based on linking two technologies - arc quenching system based on forced air flow through the specially designed arc extinguishing chamber nozzle made of material generating a gas at high temperature (polioxymethylene - POM) [1]. Parameters of generated gas (pressure and
flow) strongly impact on chamber internal temperature value and atmosphere deionization between the contacts [1, 2]. In a switch equipped with nozzle fabricated of gassing material, value of interrupted current determines also a volume of gas generated by ablating the nozzle material. Arc quenching effectiveness strongly depends on volume and pressure of cooling medium existent inside the quenching chamber. In other hand