Although rare, some small appliances, workshop tools, and certain types of space heaters, require a 30-amp, 220-volt circuit to operate, which is larger than the usual 15-amp 110-volt or 20-amp 110-volt circuits common in houses. There is nothing particularly different about installing a 30-amp circuit instead of a circuit with smaller amperage, except the plug, breaker, and wire must be rated sufficiently to handle the heavier load.
Things You'll Need
10/3 electric cable
Choose the spot you want the new plug in. If necessary, cut a hole into which the outlet box can fit.
Fasten the outlet box to the wall. If it’s new work, just nail it into a stud. If it’s old work, simply tighten the screws on the old work outlet box flaps.
Run the 10-gauge cable from the breaker panel to the location of your outlet box, and feed it through the back of the box.
Split the wires from from the cable sheath, and strip the first inch or so of the wires to expose the bare copper.
Slide the black and red wires from the cable into the hot terminals of the 30-amp plug. Slide the white wire into the neutral terminal, and the ground (bare copper) wire into the grounding terminal. Tighten each screw to secure the wires in place.
Screw the outlet into the outlet box using the screws that came with the outlet.
Turn off the power to your breaker panel.
Slide the 30-amp breaker firmly into one of the available breaker slots.
Insert the black and red wires into both terminal blocks of the 30-amp breaker, and tighten the terminal screws to fasten them in place. Insert the white wire into the neutral bus bar, and the bare copper grounding wire into the grounding bus bar, tighten the screws on both of those as well.
Turn the power to the panel back on to begin using your new 30-amp plug.
Be absolutely certain that the power is off to the panel before you begin working in it, or you will die by electrocution.