Abstract: An arc chamber barrier for a circuit breaker is provided. The arc chamber barrier has a body with a first interlock component that is structured to engage a second interlock component disposed in the circuit breaker primary cover. The arc chamber barrier body is further structured to be disposed in an elongated contact chamber at the interface of an arc chamber portion and an operating mechanism portion. In this configuration, the arc chamber barrier first interlock component resists displacement of the arc chamber barrier body when a pair of separable contacts moves between the second, closed position and the first, open position.