The diameter of the rod is the key. . 5 mm carbon rod can not afford the current of 700A. . There is gouging the clamping height. . Electrode method. . Negative carbon rod then. . The workpiece then being. . With carbon arc gouging. . 630 is enough. . In fact, the process of carbon arc gouging is not a very desirable place. . Your unit should be re-workpiece process to make changes to avoid using.