Abstract: There is disclosed a circuit breaker panel which is very compact, said panel comprising a panel board having a base, a bus bar support assembly mounted on said base, said support assembly having therein a plurality of separate bus bar receiving recesses arranged in alignment with each and perpendicular to said base, a bus bar in each of said recesses in alignment with each other and perpendicular to said base, and laterally spaced sets of terminals associated with said bus bars for electrical connection with a plurality of plug-in circuit breakers, respectively, said bus bars being disposed in the space between said terminals.