ELECTRICAL CIRCUIT-BREAKER

An electrical circuit-breaker having contacts with double rupturing, comprising two fixed contact members and at least one movable contact member. There is provided mechanism for actuating the movable contact member and including an armature which knocks away the movable contact member in case of short circuit, and two arc quenching chambers each having at least one gas outlet opening. Each quenching chamber is equipped with a U-shaped iron plate, the opening of the U facing towards the mechanism. According to the invention, the two arc quenching chambers are arranged along the two opposite sides of a separating wall of insulating material in a manner that the gas outlet opening of the chambers as well as the fixed contact members are separated mechanically and electrically by the wall, and the wall serves as a support for other structural parts of the breaker.