Control center with insulated bus bars

A control center for distributing electric power from a power supply source to power consuming devices, comprising a cabinet having a frame providing a compartment on the front side of the cabinet, a plurality of vertical bus bars in said cabinet, a barrier encasing the bus bars and being substantially coextensive therewith and consisting essentially of an electrically insulative material, at least one circuit interrupter in the compartment and having a conductor extending therefrom, the barrier having removable integral surface knockout sections adjacent to the bus bars to provide access to effect connection of the conductor to the bus bar, the knockout sections being demarked from the remainder of the barrier by a zone of reduced thickness, the knockout sections being surrounded by flanges extending from the planar area of the barrier on the side opposite the bus bars, and the barrier and the bus bars being almost completely in surface-to-surface contact with each other and without spacing therebetween except for the locations of the knockout sections when the knockout sections are removed to promote better heat conduction from the bus bars and through the barrier.