A ventilation system for switchgear has at least one chimney mounted to the roof of the switchgear enclosure. The at least one chimney has a flap mounted thereon for relieving pressure, hot gases, and particulate matter generated during an arc flash. The chimneys have grates in opposing side walls for ventilation of the switchgear. Under certain conditions, the grates allow the release of pressure below the threshold for raising the flaps. The flaps elevate when gases travel between the enclosure and an internal volume of said at least one chimney.