Abstract: A housing for a control apparatus is made of a synthetic material and includes a lower part and a cover. In the lower part are provided an upper printed board and one or more lower printed boards. Additional modules can be connected with the upper printed board by means of connectors. The lower printed boards are inserted on supporting ribs and between guiding ribs under the upper printed board and in the inserted condition they are exchangeably connected with a printed bus. At the bottom of the lower part of the housing is fastened a screening sheet. The housing of the apparatus can be realized at low costs and due to the screening sheet, a sufficient screening can be guaranteed. The two or three stages permit a compact construction of the apparatus and notwithstanding, all printed boards are easily accessible, in that the lower printed boards are to be removed without any dismounting of the upper printed board.