Abstract: A device and an apparatus for measuring the length of an electrode (14) or determining the position of a consumable cross-section (17) of the electrode (14) in an electric furnace (10), in which the measuring is performed by radar in such a manner that a radar transmitter/receiver device (22) is connected by a waveguide connection device (21) to a waveguide (20), which is arranged on the electrode (14) and extends in the consumption direction (19) of the electrode (14) from an end cross-section (18) of the electrode (14) to a consumable cross-section (17) of the electrode (14), and the time difference is measured between the emission of the radar signal an the reception of an echo generated by reflection from a discontinuity point of the waveguide in the consumable cross-section (17) of the electrode (14).