There are disclosed a method and an equipment for monitoring current drained by a grounding electrode in an electric impedance tomography system. The grounding electrode and a set of electrodes may be simultaneously applied to a patient in an electric impedance tomography apparatus. The equipment may be configured to convert current into a voltage signal and amplify, demodulate, and filter the voltage signal in order to recover its almost continuous component. The equipment may further be configured to compare the value of the continuous component with limit/threshold values proportional to an intensity of an excitation current applied to the set of electrodes. In addition to detecting the disconnection of the grounding electrode, the comparison may also detect the disconnection of one or more tomography electrodes, as well as unbalance in the currents injected through the electrodes and the contact of the patient with voltage sources or conductive bodies.