A circuit breaker for metalclad switchgear use is provided using vacuum-interrupter elements in substitution of the usually provided magnetic and insulating plate structures, customarily employed. A resilient mounting for the interrupter elements is provided, together with massive end contact blocks for heat dissipation generated within the vacuum-interrupter elements. A pivoted operating lever, connected to the massive contact block secured to the moving contact of the vacuum-interrupter, is operated by a resilient connection to the insulating operating rod of the circuit breaker. Because of the reduced dimensions, the cubicle dimensions may be drastically reduced, if desired.