A system for detecting contact and proximity between ablation electrodes by sensing changes in voltage morphology of non-activated electrodes, the system comprising: a catheter , which is configured for insertion into a body of a patient , the catheter comprising at least a first electrode , a second electrode and a third electrode , which are disposed at a distal end of the catheter and are configured to contact tissue within the body; a pulse generator , which is configured to apply one or more bipolar ablation pulses between the first and second electrodes , for ablating the tissue in contact with the first and second electrodes ; and a controller , which is configured to: (i) control the pulse generator to apply the one or more bipolar ablation pulses between the first and second electrodes , and (ii) detect that a distance between (i) at least one of the first and second electrodes, and (ii) the third electrode, is smaller than a distance threshold; characterized in that : the controller is configured to receive a signal indicative of a voltage, measured between the third electrode and a reference during application of the ablation pulses, the distance is detected by detecting that the voltage violates a predefined criterion, and the controller is further configured to issue a notification in response to detecting that the voltage violates the predefined criterion. a catheter , which is configured for insertion into a body of a patient , the catheter comprising at least a first electrode , a second electrode and a third electrode , which are disposed at a distal end of the catheter and are configured to contact tissue within the body; a pulse generator , which is configured to apply one or more bipolar ablation pulses between the first and second electrodes , for ablating the tissue in contact with the first and second electrodes ; and a controller , which is configured to: (i) control the pulse generator to apply the one or more bipolar ablation pulses between the first and second electrodes , and (ii) detect that a distance between (i) at least one of the first and second electrodes, and (ii) the third electrode, is smaller than a distance threshold; (i) control the pulse generator to apply the one or more bipolar ablation pulses between the first and second electrodes , and (ii) detect that a distance between (i) at least one of the first and second electrodes, and (ii) the third electrode, is smaller than a distance threshold; characterized in that : the controller is configured to receive a signal indicative of a voltage, measured between the third electrode and a reference during application of the ablation pulses, the distance is detected by detecting that the voltage violates a predefined criterion, and the controller is further configured to issue a notification in response to detecting that the voltage violates the predefined criterion. the controller is configured to receive a signal indicative of a voltage, measured between the third electrode and a reference during application of the ablation pulses, the distance is detected by detecting that the voltage violates a predefined criterion, and the controller is further configured to issue a notification in response to detecting that the voltage violates the predefined criterion. <EOS>