A switchgear cabinet assembly or rack assembly including an electric supply device that can be or is connected to a primary power supply. Equipment that is housed in at least one switchgear cabinet or rack on the user side, or equipment that is to be supplied with electricity can be or is connected to the electric supply device. To achieve simple and reliable connection options, a sub-distribution device is located in the switchgear cabinet or rack or in a separate cabinet or rack. The device has at least one sub-distribution unit that can be or is connected to the primary power supply, having a housing or frame and being retained and secured by a mounting unit. According to this invention, the sub-distribution unit can be or is connected to primary supply lines that lead to the primary power supply and to pre-fabricated connection lines that lead to the rack.