Abstract: An improved electric control center comprising a plurality of drawout type switchgear units housed in a cabinet having incorporated therein an integral air-ventilation duct system of modular snap-fitting construction having at least one air intake opening located at the bottom of the cabinet, one air exhaust opening at the top of the cabinet, and a plurality of branch ducts that communicate with a plurality of tandem compartments that are in stacked relationship and contain the respective switchgear units. The heat generated by the switchgear units and associated bus bars is thus removed from the cabinet by the air flow through the ventilator duct system.