Welding requires high levels of electricity to create the welding arc necessary to melt the steel and create a weld bead. This welding power supply can be found in several providers. The most common welding power supply is found in the form of 220- or 440-volt electric service from the power provider in any given area of the world. Typically wired into a dedicated power supply box, the electrical service is delivered into the welding shop by overhead or underground wires and supply lines from the power supply or utility company. Also prevalent on job sites where power has not yet been installed is the portable or generated welding power supply, which are commonly gasoline- or diesel-powered generating stations that can be attached to the welder or independently wired to the welder.
The welding power supply that is common from a hardwired supply tapped into a power company feed is usually of the alternating current (AC) type of electricity. The AC welding power supply allows for the welding of most materials and is common in most types and forms of welding found worldwide. This power, however, is greater than the typical household power used, and in most cases, it is double the power. This calls for a dedicated power box or fuses designed to allow the higher power flow without blowing circuits as the welder is used.
In some cases, however, direct current (DC) is required to weld a material. In these cases, most high-end welders have the ability to switch between AC and DC current settings and the welder simply throws a switch on the welder and completes the weld. In other circumstances, the welder is able to use a self-generated type of welding power supply commonly known as a portable welder or construction site welder. This welder is attached to a small, fuel-powered engine/generator unit and is capable of generating enough power to weld.
This form of portable welding power supply is able to sustain arc, tungsten inert gas (TIG) and metal inert gas (MIG) welding. When it is used to arc or stick weld, a special DC welding rod must be used to prevent the sticking of the rod to the steel being welded. Occasionally, carbon rods are used to create the required heat to weld steel. The welding power supply used to heat these carbon rods can be either from the power supplier or a portable power generator. Although dependable and reliable, the power from a utility provider is typically preferred over that of a generator when it is available as a welding power supply choice.