The National Electrical Code began requiring 4-prong receptacles for 220-volt residential circuits in 2000, but it doesn't prohibit you from using your older dryer with a 3-prong cord. Instead, it allows you to change the cord so that the dryer can be plugged into a modern receptacle, and the procedure isn't very complicated. Four-prong dryer cords, or pigtails, are available at hardware and electrical supply stores, and usually cost less than $20. To make the switch, you'll need a green ground screw to attach to the dryer body so the machine can be grounded by the ground wire.
Unplug the dryer and move it to an accessible spot. Unscrew the plate on the back that covers the electrical terminal with a screwdriver. You'll find the cover on the back of the dryer near the bottom of the machine at the point where the cord exits.
Loosen the three terminal screws holding the cord. Before you remove them and take off the cord, note the colors of the screws and the wires attached to them. The screws holding the black and red wires are brass and the one holding the white wire is silver.
Remove the ground strap from the silver terminal. It may be a small metal plate or a length of wire connecting the terminal to the body of the dryer. You may be able to pull it out with pliers, or you may have to loosen a screw to remove it. Its function was to ground the dryer, and that function will now be served by the ground wire on the new pigtail.
Insert the brass terminal screws into the ring lugs attached to the red and black wires on a replacement pigtail and the silver screw into the ring lug on the white wire. Drive the screws into the same slots from which you removed them and tighten them securely with a screwdriver.
Drill a 1/4-inch hole in the body of the dryer within reach of the fourth wire in the pigtail, which is green. Insert a green ground screw through the ring lug on the end of that wire, drive the screw into the hole and tighten it securely.
Feed the cord through the notch on the terminal cover plate and screw the cover plate to the back of the dryer.
Things You Will Need
- 1/4-inch drill bit
- Ground screw
- 4-prong pigtail
- There usually isn't room behind the cover plate to install the ground screw. If not, it's acceptable to attach the screw to the back of the dryer outside the plate.
- Check the grounding with a multimeter before you plug in the dryer. Set the meter to ohms, touch one lead to the dryer body and touch the other lead to the ground prong on the plug. The meter should show less than 10 ohms of resistance.