ARC responsive thermal circuit breaker

A circuit breaker comprising an electrically insulative housing, a stationary electrical contact mounted in the housing, a movable electrical contact mounted in the housing movable into and out of engagement with the stationary contact, a latch having a movably mounted latching surface, a contact opening mechanism connected to the movable contact and having a catch received on the latching surface, a spring biasing the contact opening mechanism toward a contact opening position with the engagement of the catch on the latch preventing such movement, a bimetallic element connected to the stationary contact to conduct current when the movable contact is engagement with the stationary contact, the bimetallic element bending in a selected direction upon self-heating due to the conduction of current therethrough, a movable connecting plate extending from the bimetallic element to the latch, the bimetallic element bending sufficiently upon a current overload to move the connecting plate to in turn relatively move the latch from the catch to thereby trip the circuit breaker by allowing the contact opening mechanism to move the movable contact out of contact engagement with the stationary contact, an arc sensing circuit and an arc responsive actuator mounted in the circuit breaker, the arc responsive actuator positioned to move the latch relative to the catch, the arc sensing circuit, upon sensing an arc in the circuit connected to the stationary and movable electrical contacts, causing the arc responsive actuator to be energized to move the latch relative to the catch and trip the circuit breaker.