a high voltage circuit breaker with insertion of resistance on closing , wherein the resistance is inserted by a fixed insertion electrode co - operating with the end of the moving main contact , the blast nozzle and the arcing contact of the moving assembly being secured to each other , and the subassembly being movable relative to the moving assembly so that on triggering , because of the inertia of said subassembly , the arcing contacts separate after the insertion electrode and the end of the moving main contact have moved sufficiently far apart .