Abstract: An enclosure for a circuit breaker includes a housing sized to support at least one circuit breaker and to permit electrical connections to be made to the circuit breaker. A housing cover or lid is movable between an open position in which the circuit breaker is accessible and a closed position in which access to the electrical connections of the circuit breaker is prevented. An actuating bar is mounted slidably to the lid, and includes a switch-engaging formation for engaging the operating lever of the circuit breaker. The actuating bar includes a switch-engaging formation for engaging the operating lever of the circuit breaker and is operable to move the operating lever between the first, active position and a second, inactive position. An interlocking formation in the form of a waisted portion defined in the bar is adapted to prevent opening of the cover when the switch operating lever is in the first position and to allow opening of the cover when the operating lever is in the second position.