A connection device for electrical conductors, having - a body having an interior and an insertion opening for inserting the electrical conductor in an insertion direction into the interior; - a spring unit arranged in the interior for clamping and contacting the electrical conductor; - an actuating device for disengaging the spring unit from a clamping position; - wherein the actuating device comprises a plunger having a pressure edge, which is arranged so it is displaceable in the body; - the spring unit has at least two spring sections, at least one of which is formed as a clamping spring; - wherein one of the at least two spring sections of the spring unit is a clamping spring having a clamping edge for clamping the conductor and another of the at least two spring sections of the spring unit is a compression spring having a pressure section for acting on the conductor; - wherein the plunger of the actuating device interacts with the spring section of the spring unit formed as a clamping spring; characterized in that - the spring unit has a sigma shape, and therefore the spring unit is embodied in one piece, wherein the two spring sections of clamping spring and compression spring are connected to one another or merge into one another; and - wherein the pressure edge of a lower end of the plunger interacts with a surface of a curved section of the clamping spring of the spring unit such that a clamping section is bent downward against a spring force of the curved section and simultaneously bears on the surface of a pressure curved section of the compression spring and compresses it against the spring force of the pressure curved section and the curved section of the compression spring. - a body having an interior and an insertion opening for inserting the electrical conductor in an insertion direction into the interior; - a spring unit arranged in the interior for clamping and contacting the electrical conductor; - an actuating device for disengaging the spring unit from a clamping position; - wherein the actuating device comprises a plunger having a pressure edge, which is arranged so it is displaceable in the body; - the spring unit has at least two spring sections, at least one of which is formed as a clamping spring; - wherein one of the at least two spring sections of the spring unit is a clamping spring having a clamping edge for clamping the conductor and another of the at least two spring sections of the spring unit is a compression spring having a pressure section for acting on the conductor; - wherein the plunger of the actuating device interacts with the spring section of the spring unit formed as a clamping spring; - the spring unit has a sigma shape, and therefore the spring unit is embodied in one piece, wherein the two spring sections of clamping spring and compression spring are connected to one another or merge into one another; and - wherein the pressure edge of a lower end of the plunger interacts with a surface of a curved section of the clamping spring of the spring unit such that a clamping section is bent downward against a spring force of the curved section and simultaneously bears on the surface of a pressure curved section of the compression spring and compresses it against the spring force of the pressure curved section and the curved section of the compression spring.