A locking assembly is for the trip bar of a circuit breaker. A pivotal trip lever is coupled to the trip bar, in order to move therewith. The locking assembly includes: a locking mechanism, such as a commercially available key lock, with a pivotal element; a mounting plate, which receives the key lock and secures it to the circuit breaker; an extension member coupled to the pivotal element; and a flexible linkage interconnecting the pivotal trip lever and the extension member.