A terminal clamp cover device for low voltage circuit breakers, in particular for molded case circuit breakers, having one or more phases, each provided with a terminal for the electrical connection of the circuit breaker, a clamp for the connection of the terminal to an electrical circuit and a vent opening to discharge the gases produced in the circuit breaker during opening/closing operations. The device includes an insulating body that covers the clamp, the insulating body being provided on at least one portion of its outer surface with a plurality of heat dissipating elements. A low voltage circuit breaker, in particular a low voltage molded case circuit breaker, including a device of the type described also forms part of the application.