Abstract: A resistor type arc welding machine comprises a housing capable of containing a cooling liquid; first and second main resistors serially connected to each other, the free end of the first resistor being connected to the current line of an alternating current source and the free end of the second resistor being connected to a holder for a welding electrode; one or more taps from intermediate points along said first and second main resistors, which taps may be connected, preferably through respective by-pass resistors, to the said holder instead of the free end of said second main resistor, to provide higher amperage outlets; and a direct line whose first end is connected to ground and whose second end is connected to the work piece to be welded, in order to complete the electrical circuit and to produce the welding arc; the above mentioned main resistors being arranged in an open and perforate support fixed in said housing such that the resistors will be continuously and completely submerged in the cooling liq