Objects of the research were a typical air insulated LBSs dedicated for interrupting maximum load currents ranged from 400 A to 1250 A at 12/24 kV. In the tested objects, depends on the current value and recorded arcing time, different factor takes a main role for arc quenching efficiency (air blow or gassing material). For this reason, functional analysis aimed at gas pressure measurements inside the extinguishing chamber in direct vicinity of switching arc plasma was executed utilizing elaborated tests stand