Abstract: A method for charting onto a newly produced map mains network data from an old, existing map. It comprises the following steps. In a first memory part is stored the measured data for a new map. In a second memory part is stored the data of the old map including the data relating to mains networks. From the memory parts the new and the old map are read and displayed on a display. Reference points of the old map are moved until they coincide with the appropriate reference points of the new map. Finally, The network reference points moved with the reference points of the old map are interpolated so that the network data is included in the new map.