Some manufacturers have undertaken tests on metal-clad switchgear to preclude this from taking place and, instead, contain the arc within the bus compartment of any feeder cell. Arc resistant tests based on one high and two high breaker design have been successfully undertaken. The compression stage starts at time zero and ends when pressure can no longer increase. This typically lasts 5 to 10 milliseconds. The expansion stage starts when the pressure relief doors, located at the top of the switchgear, begin to open.
Gas flow is characterized by wave motion.
Expansion stage typically lasts 5 to 10 milliseconds. Emission stage starts when the pressure relief doors have opened and ends when the gas in the cell reaches arc temperature. This typically lasts 50 to 100 milliseconds. Thermal stage lasts until the arc is extinguished and combusting materials are consumed. This lasts until the arc is extinguished and every thing has cooled down to room temperature.