An electrical connecting device (10) comprising an electrical insulating body (20) with at least one pair of longitudinal parallel seats (23) and (24) adapted to house, respectively, a connecting element (30) with a spring terminal and an actuator pin (40) having a cam profile oriented towards a spring (32) of the terminal to cause the opening and closure of the terminal by sliding into the corresponding seat, said spring (32) being a ring-shaped spring having a curved lower portion (34), a back ascending portion in form of a leg (35) engageable with a projecting portion (41) of said cam profile of the actuator pin (40) and an upper portion (36) with a slot (37) adapted to receive at least one electric conductor (60), wherein said cam profile of the actuator pin (40) has at least a tapered side (45) and a remaining ribbed portion (46), and that said back ascending portion in form of a leg (35) of the spring (32) has a corresponding groove (39) apt to house said at least one ribbed portion (46) of the actuator pin (40) in the maximum extroversion status of the spring, that is when the terminal is closed and empty.