The central control unit with an output of 6 x 8 amps significantly reduces installation time. All consumers to be installed are simply connected to the control unit. This eliminates the need for time-consuming installation of individual switches in the driver's cab. The control unit and the switch box are simply connected with a thin telephone cable. The LEDs on the control unit provide a location and function indicator. In addition to the control unit, the switch box and the cable are also included in the scope of delivery.