Apparatus for receiving electrical components, such as switches, plug sockets, motion detectors, sensors and/or probes, for controlling the climate in a room, comprising a receptacle part or receptacle housing for surface-mounting or, in particular, flush-mounting which can be connected to an electrical power supply system, wherein the receptacle part or receptacle housing for receiving a plurality of electrical components which are arranged in series is permanently connected to the power supply system with the aid of connection elements and has uniform-size and/or one or more standardized recesses into which the electrical components, such as switches, plug sockets and motion detectors, sensors or probes, can be inserted and, after the insertion process, the said electrical components are directly connected to the power supply system and/or other electrical devices with the aid of contact elements, characterized by the following features: a) the receptacle part or receptacle housing has contacts which can be permanently connected in the state in which said receptacle part or receptacle housing is mounted on the electrical power supply system, the said contacts being automatically connected to the electrical power supply system by insertion of the electrical component into the receptacle part or receptacle housing from above; b) one or more guide elements are provided in the receptacle part or receptacle housing, the said guide elements interacting with one or more guide elements, which are provided on the electrical component, during the process of inserting the electrical component into the recess in the receptacle part or receptacle housing, and orienting the electrical component in such a way that, in the inserted state, the electrical component is operatively connected to the electrical power supply system or another electronic component; c) the outer contour of the individual electrical components is approximately identical, so that they can be inserted into any desired recess in the receptacle part or receptacle housing; d) the individual recesses in the receptacle housing have a rectangular, round, oval or polygonal cross section which approximately corresponds to the other inner contours and is configured in such a way that each electrical component with a different function can be inserted into the recess; and e) the receptacle part or receptacle housing can be expanded by further receptacle parts or receptacle housings which can be connected to one another with the aid of connecting elements, in particular force-fitting and/or interlocking elements. a) the receptacle part or receptacle housing has contacts which can be permanently connected in the state in which said receptacle part or receptacle housing is mounted on the electrical power supply system, the said contacts being automatically connected to the electrical power supply system by insertion of the electrical component into the receptacle part or receptacle housing from above; b) one or more guide elements are provided in the receptacle part or receptacle housing, the said guide elements interacting with one or more guide elements, which are provided on the electrical component, during the process of inserting the electrical component into the recess in the receptacle part or receptacle housing, and orienting the electrical component in such a way that, in the inserted state, the electrical component is operatively connected to the electrical power supply system or another electronic component; c) the outer contour of the individual electrical components is approximately identical, so that they can be inserted into any desired recess in the receptacle part or receptacle housing; d) the individual recesses in the receptacle housing have a rectangular, round, oval or polygonal cross section which approximately corresponds to the other inner contours and is configured in such a way that each electrical component with a different function can be inserted into the recess; and e) the receptacle part or receptacle housing can be expanded by further receptacle parts or receptacle housings which can be connected to one another with the aid of connecting elements, in particular force-fitting and/or interlocking elements.