Abstract: A member for measuring a variable representative of a common mode voltage in an electrical network a device. The network or the device includes at least a first power conductor and a second power conductor. The measuring member has two capacitive elements which are intended to be arranged in a bridge between the two power conductors and have capacity values that are identical to each other. The two capacitive elements are connected at a midpoint. The measuring member also includes a two-terminal measurement circuit connected on the one hand to the midpoint and on the other hand to a connection terminal intended to be electrically connected to a common conductor provided in the electrical network or device.