The two twin-electrode DC furnaces at Koniambo Nickel SAS (KNS) have suffered from a loss of arc (LOA) problem since commissioning. LOA manifests itself by the sudden extinguishing of the electric arc between the electrode tip and slag bath. LOA occurred randomly with no clear correlation to process parameters. Lost power from LOA led to large fluctuations of the power-to-feed ratio in the furnace. The inability to run at stable high power and frequent stoppages to correct power-to-feed imbalances were the main barriers to achieving the nominal furnace design production rate. Heuristic process levers were developed to reduce the occurrence of LOA. None showed systematic and reproducible benefits to LOA reduction, and the root cause remained unknown. Bench scale tests were run that clearly and reproducibly showed the events leading up to LOA. These events are explained using electromagnetic theory. The LOA problem was solved by reversing the polarity of one electrode, which converts the attractive force experienced by the arcs into a repulsive force. Both furnaces were converted to this new configuration by the physical rotation of the rectifier thyristors of one electrode. Following the change, LOA frequency was drastically reduced. Furnace power setpoints above 100 MW are now readily achieved with no need for constant process parameter adjustments. The increased electric stability has led to increased process stability with no negative consequences to furnace integrity.