Installation switching device having a housing and having a screw connecting clamp

An installation switching device, comprising:

• a housing;
• a screw connecting clamp including an essentially frame-shaped clamping part including longitudinal faces, narrow faces, and broad faces;
• a head clamping screw configured to be received in a threaded aperture of the clamping part;
• and
• a current rail arranged in a fixed manner in the installation switching device, the current rail extending through an interior of the frame-shaped clamping part,
• wherein a current rail broad face is oriented, as assembled, parallel to a clamping part broad face facing the head clamping screw, and
• wherein the head clamping screw supports itself, screwed-in, on the current rail and, consequently, the clamping part can be displaced in its longitudinal direction, parallel to one of the narrow faces, relative to the current rail during further screwing in the head clamping screw so that a connecting conductor can be fixedly clamped between a face of the current rail remote from the head clamping screw and the broad face of the clamping part that is remote from the head clamping screw,
• wherein the housing includes a screw receiving region configured to guide a screw head of the head clamping screw laterally in its axial movement direction,
• wherein the screw receiving region includes a housing-side screw access aperture that opens an access to the screw head,
• wherein the screw receiving region includes a delimiter configured to prevent the screw head from penetrating the screw access aperture,
• wherein a thread-free end section is located on an end section of a screw shaft of the head clamping screw lying opposite the screw head,
• wherein a threaded section is located on an intermediate section of the screw shaft of the head clamping screw between the screw head and the thread-free end section,
• wherein, the clamping part and the head clamping screw are operatively configured such that in the case of the head clamping screw being rotated out, the thread-free end section of the head clamping screw is located further within the threaded aperture when the thread of the clamping screw is no longer in engagement with the thread of the threaded aperture so that the head clamping screw can be further rotated in this position without a position of the clamping part changing further,
• wherein the head clamping screw is dimensioned such that a length from a lower most delimiter contact point of the screw head to an end of the threaded section of the screw shaft is approximately equal to a distance from a top of the clamping part to a lower most portion of the delimiter that is configured to contact the screw head,
• wherein the screw receiving region is dimensioned such that the screw head of the head clamping screw is guided therein such that the screw head can be displaced in an axial displacement direction in relation to a longitudinal center axis of the screw shaft,
• wherein the screw receiving region comprises walls bounding at least two sides of the screw head that prevent the screw head from tilting,
• wherein the screw receiving region comprises a transition in the direction away from the front face into a clamp receiving chamber, the clamp receiving chamber being configured to receive the screw connecting clamp and being wider than the screw receiving region,
• wherein a length of the screw receiving region in the axial direction from the delimiter to the transition is configured such that at least a portion of the screw head remains within the screw receiving region from an entirely opened screw connecting clamp state to an entire closed screw connecting claim state.