Patent ID: 7918693

Claim:
An electrical apparatus comprising: a terminal screw for connection of electrical conductors, a housing with a shaft in which is provided a screw with a screw driver opening, wherein said screw is radially enclosed by the shaft and turnable only by its screw driver opening, whereby a screw head and the shaft are adjusted relative to one another in such a way that during a revolution of the screw in a first rotational angle range a minimal torsional moment is traversed and in a second rotational angle range a maximum torsional moment is traversed, wherein the screw head features a maximal screw head diameter and, relative to it, a reduced screw head diameter, wherein the shaft has a first shaft diameter, which corresponds to the maximal screw head diameter, and a smaller second shaft diameter, and whereby a surface area of the screw head is curved in a range of the maximal screw head diameter and planar in a range of the reduced screw head diameter in such a way that a planar surface on the screw head necessarily follows a curved surface on the screw head and vice versa.