Abstract The electromagnetic shielding of high-voltage (HV) cables has been studied both by numerical computations and by experiments performed in real-life practical situations. Two shield topologies have been considered, i.e. open- versus closed-shield configurations. The open-shield configuration consists of placing horizontally plates on the ground. The closed-shield configuration consists of a formed cable conduct base in which the HV cable is placed, and on which a cover is mounted. HV cables (150 kV) were studied in both experimental trials. With respect to the considered materials in the experiments, the ferromagnetic hot-rolled low-carbon material Magnetil ® is used (ferromagnetic material), and its behaviour is compared to the shielding based on aluminium (conductive non-magnetic material). Briefly, the following average shielding factors (SF) are obtained with open-shield configurations: SF around 2 when using Magnetil ® , SF around 4 when using aluminium. In closed-shielding configurations, a much more performant shielding behaviour is experimentally obtained, namely SF around 20 when using Magnetil ® , while SF around 8 when using aluminium. The optimum shielding behaviour is thus obtained by a ferromagnetic closed shield.