A multiwire shielded cable (14) for a data network is for example pre-installed in the wall (45) of a building. The end of the cable (14) enters a housing part (66) and is coupled to a Western connector (10) or another connector having a similar design, whatever the connector system that will be later used. When the user-specific equipment is later installed, a modular housing (29) is inserted into the housing part (66). The modular housing (29) has an input tip jack compatible with the connector (10) and another tip jack on the side of the user which may be a jack of the Western type, an IBM data jack or a BNC jack (27). The connector (10) is provided with a metallic shield which directly contacts the shielding of the cable (14) and the metallic shield of the input tip jack, which in turn is electrically connected to the metallic modular housing (29). An easily adaptable data installation system is thus obtained, in which the area from the end of the cable to the user-specific tip jack (27) is very effectively protected against perturbing radiation.