An electric arc welder for depositing weld metal along a groove between two edges of a metal workpiece. The welder comprises: a leading electrode driven toward a point in the groove by a first wire feeder operated at a first speed by a first motor with a speed control input and a tachometer derived first feedback signal, a trailing electrode driven toward the same point by a second wire feeder operated at a second speed by a second motor with a speed control input and a tachometer derived second feedback signal, a first power source directing a first current to flow through the leading electrode and a second power source causing a second current to flow through the trailing electrode with the current flow being in a series arc circuit. The second power source being grounded to the workpiece to modify the series arc current so ground current flows to the workpiece whereby the second current is generally equal to the first current minus the ground current.