Arc welding is the fusion of two pieces of metal by an electric arc between the pieces being joined –the work pieces – and an electrode that is guided along the joint between the pieces. The electrode is either a rod that simply carries current between the tip and the work, or a rod or wire that melts and supplies filler metal to the joint. The basic arc welding circuit is an alternating current (AC) or direct current (DC) power source connected by a “work” cable to the work piece and by a “hot” cable to an electrode. When the
electrode is positioned close to the work piece, an arc is created across the gap between the metal and the hot cable electrode. An ionized column of gas develops to complete the circuit.