Conductivity meter for measuring an electrical conductivity of a liquid medium, having a housing, a conductive first measuring cell and a control device for controlling the first measuring cell, wherein the first measuring cell has a first conductivity measuring range and a first electrode and a second electrode characterized in that the conductivity meter has a second measuring cell with a second conductivity measuring range, that the first measuring cell, the second measuring cell and the control device are arranged on the housing, that the control device is designed for controlling the second measuring cell, that the first measuring cell and the second measuring cell are designed in such a way that the first conductivity measuring range and the second conductivity measuring range overlap, so that the conductivity meter has a continuous conductivity measuring range, that the control device is designed - to determine an electrical conductivity of the medium, if the electrical conductivity lies both in the first and in the second conductivity measuring range, on the one hand with the first measuring cell and on the other hand also with the second measuring cell, so that the determination of the electrical conductivity has redundancy, - to determine a first conductivity of the medium with the first measuring cell and a second conductivity of the medium with the second measuring cell - and, if the determined first conductivity and/or the determined second conductivity lie in an overlap conductivity measuring range and the determined first conductivity differs from the determined second conductivity by more than one conductivity tolerance value, signaling an error. that the conductivity meter has a second measuring cell with a second conductivity measuring range, that the first measuring cell, the second measuring cell and the control device are arranged on the housing, that the control device is designed for controlling the second measuring cell, that the first measuring cell and the second measuring cell are designed in such a way that the first conductivity measuring range and the second conductivity measuring range overlap, so that the conductivity meter has a continuous conductivity measuring range, that the control device is designed - to determine an electrical conductivity of the medium, if the electrical conductivity lies both in the first and in the second conductivity measuring range, on the one hand with the first measuring cell and on the other hand also with the second measuring cell, so that the determination of the electrical conductivity has redundancy, - to determine a first conductivity of the medium with the first measuring cell and a second conductivity of the medium with the second measuring cell - and, if the determined first conductivity and/or the determined second conductivity lie in an overlap conductivity measuring range and the determined first conductivity differs from the determined second conductivity by more than one conductivity tolerance value, signaling an error. - to determine an electrical conductivity of the medium, if the electrical conductivity lies both in the first and in the second conductivity measuring range, on the one hand with the first measuring cell and on the other hand also with the second measuring cell, so that the determination of the electrical conductivity has redundancy, - to determine a first conductivity of the medium with the first measuring cell and a second conductivity of the medium with the second measuring cell - and, if the determined first conductivity and/or the determined second conductivity lie in an overlap conductivity measuring range and the determined first conductivity differs from the determined second conductivity by more than one conductivity tolerance value, signaling an error.