Electrical connecting device including an insulating body with parallel longitudinal seats and, respectively adapted to accommodate a connecting element with spring terminal and an actuator pin with profile cam facing a spring of the terminal to cause the opening and closing of said terminal by means of sliding in the corresponding seat, said spring being a ring-shaped spring with a curved lower portion, a back ascending portion engageable by a protruding portion of said cam profile of the actuator pin and an upper portion with a slot adapted to receive at least one electrical conductor, characterized in that in said actuator pin a hollow seat delimited by two lateral walls is provided adapted to receive the aforementioned ascending leg of the spring-shaped ring in condition of maximum extroversion of the spring, i.e. upon empty closed terminal.