Method for configuring a switching cabinet which comprises modularly designed switching cabinet equipment which is assembled in an application-specific manner from a number of electrical and/or electronic built-in modules (2a - 2d) and further optional components, according to the following steps: - Preparation of a functional design of the switching cabinet equipment in the form of an electrical circuit diagram (SP), - conversion of the electrical circuit diagram (SP) of the switching cabinet equipment into a three-dimensional layout (L1) for the arrangement of at least a number of electrical and/or electronic built-in modules (2a - 2d) in at least one switching cabinet housing , wherein the three-dimensional layout (L1) of the switching cabinet equipment is prepared by a software-technical layout assistance unit (LA) in access to an installation module library (B) connected thereto, characterised by an - modification of the prepared three-dimensional layouts (L1) by a modification algorithm (Mod) implemented in the layout assistance unit (LA) for generating at least one alternative three-dimensional layout (L2), the modification algorithm (Mod) for modifying the layout (L1) into the alternative layout (L2) determining values of a quality function and optimizing the modification in such a way that the quality function assumes an extremum, in that the modification algorithm (Mod) includes a parameterizable quality function to which a number of different layout optimization parameters (P1 ... Pn) are given, selected from a parameter group comprising space utilization level, load level, power consumption level, EMC level, wiring length level, where the layout optimization parameters (P1 ... Pn) provide an input to the planner for different optimization directions to select desired weightings for a layout modification, - handover for assembly of the switching cabinet according to the alternative three-dimensional layout (L2). - Preparation of a functional design of the switching cabinet equipment in the form of an electrical circuit diagram (SP), - conversion of the electrical circuit diagram (SP) of the switching cabinet equipment into a three-dimensional layout (L1) for the arrangement of at least a number of electrical and/or electronic built-in modules (2a - 2d) in at least one switching cabinet housing , wherein the three-dimensional layout (L1) of the switching cabinet equipment is prepared by a software-technical layout assistance unit (LA) in access to an installation module library (B) connected thereto, characterised by an - modification of the prepared three-dimensional layouts (L1) by a modification algorithm (Mod) implemented in the layout assistance unit (LA) for generating at least one alternative three-dimensional layout (L2), the modification algorithm (Mod) for modifying the layout (L1) into the alternative layout (L2) determining values of a quality function and optimizing the modification in such a way that the quality function assumes an extremum, in that the modification algorithm (Mod) includes a parameterizable quality function to which a number of different layout optimization parameters (P1 ... Pn) are given, selected from a parameter group comprising space utilization level, load level, power consumption level, EMC level, wiring length level, where the layout optimization parameters (P1 ... Pn) provide an input to the planner for different optimization directions to select desired weightings for a layout modification, - handover for assembly of the switching cabinet according to the alternative three-dimensional layout (L2). <EOS>