A DC balanced square wave power source, controlled in a constant voltage mode, for ESW and ESW-NG welding systems and methods can be matched with variable speed wire electrode feeders, multiple guide tubes, articulated air-cooled cooper welding shoes, and multiple pass ESW welding systems, thus gaining the following advantages, namely, controlling weld bead shape, reducing base metal dilution, reducing total heat input into the parent material, and reduction or elimination of any DC magnetic field in the weld cavity.