Changing Dryer Cords From 4-Wire to 3-Wire

3-Prong And 4-Prong Electric Dryer Cords
3-Prong And 4-Prong Electric Dryer Cords. Timothy Thiele

Newer homes are now being equipped with 4-prong dryer cord plugs. This is the new standard and is required under Article 550.16(A)(2) of the National Electrical Code (NEC) 2008. Connections of electrical clothes dryers shall be made with a 4-conductor cord and 3-pole, 4-wire, grounding-type plugs or by Type AC cable.

The electrical connection cover plate can be removed easily with a nut driver to gain access to the electrical connections. To remove the electrical connection cover plate on an electric dryer, simply slide the slotted side of the plate from the slot provided on the dryer after removing the retaining screw using a nut driver.

In order to protect the 4-prong electric dryer cord and hold it securely in place, a strain relief cord connector is used. This serves two purposes by keeping the cord from being cut on the metal of the machine and it protects the electrical connections from being pulled loose if the cord is pulled on.

In order to remove the clamp, squeeze the two halves together with pliers and remove the two screws using a screw driver or drill with a screw head. Remove the two halves of the clamps and the cord is ready to be removed.

Removing a 4-prong electric dryer cord when replacing it with a 3-prong electric dryer cord is easy when you follow these directions. First, disconnect the black wire, one of the "hot" connections, from the left side post by removing the terminal screw. This is one-half of the 240-volt connection.

Next, disconnect the red wire, another of the "hot" connections, from the right side post by removing the terminal screw.

This is the other half of the 240-volt connection. Then, disconnect the white wire from the center connection. It is used for the neutral connection. Now, disconnect the green wire from the machine case by unscrewing the green screw.

The next step is critical to return your electrical connection to factory condition before installing the 3-prong cord! Locate the white machine wire that is now connected to the neutral (center) screw terminal. Disconnect it from there and install it under the green ground screw.

In order to install a 3-prong dryer cord, insert the cord into the installation hole provided in the electrical connection access box in the rear of the electric dryer.

Unscrew the three connection screws using a magnetic nut driver, so the screws don't fall down inside of the machine. Connect the outer two wires (hot wires) to the outer two screws, obviously, one on each screw. Now connect the center wire (neutral) to the center post.

You'll notice the white machine wire is now the case ground connection, unlike the 4-prong cord connection in which the green wire from the cord makes the ground connection.

In order to protect the 4-prong electric dryer cord and hold it securely in place, a strain relief cord connector is used. This serves two purposes by keeping the cord from being cut on the metal of the machine and it protects the electrical connections from being pulled loose if the cord is pulled on.

Slide one half of the clamp into the connection hole under the cord wire. This will be the half with the smaller holes.

The clamp is bent at a 90 degree angle, so you'll have to twist it into place with the holes facing up.

Now, install the larger-holed clamp half in the same manner. Squeeze the two halves together with pliers and insert the two screws into the holes. Using a screw driver or drill with a screw head, tighten the two screws equally until snug.

The electrical connection cover plate can be attached easily with a nut driver to cover the electrical connections. To install the electrical connection cover plate on an electric dryer, simply slide the slotted side of the plate into the slot provided on the dryer. Line the plate screw slot up with the mounting screw hole and insert the cover plate retaining screw using a nut driver.