Mounting base with arc plenum

The present invention relates generally to a switchgear apparatus. More particularly, the invention encompasses a mounting base with arc plenum for a switchgear apparatus. The present invention also relates to enclosures for switchgear, panel boards, circuit breakers, and more particularly to an enclosure for low voltage switchgear and switchboard assemblies. The enclosure can be a walk-in type enclosure or a non-walk-in type enclosure. This invention further provides a method and apparatus for channeling plasma (hot arc gasses) that are generated from an arc. The switchgear mounting base with internal arc plenum can be an integral part of an arc resistant switchgear assembly and is preferably located under the switchgear. The switchgear mounting base works in conjunction with a ventilation system in the switchgear apparatus to channel hot arc gasses (plasma) from the lower breaker compartments in the front of the switchgear in the event of an internal arcing fault in one of the breaker compartments. The hot arc gasses exit downward from the bottom of the switchgear and into the plenum. The gasses then are channeled to travel backward through the plenum and then up again into the switchgear rear compartment where they can be routed to and safely discharged from the roof of the switchgear apparatus.