DIY Appliance Repair: Changing an Electric Dryer or an Electric Range's Power Cord

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Beginning with the 1999 Revision of the National Electric Code, all newly installed dryer and electric range circuits were required to be wired with a 4-wire receptacle. This requirement applied to newly installed circuits in homes built before 1999 and t

Prior to the 1999 Revision of the NEC, appliance manufacturers were permitted to bond the metal frames of dryers and electric ranges over to the white, neutral conductor. The system's neutral conductor is the “Grounded Conductor” and is bonded over to the system's grounding conductor at the service panel. Beginning with the 1999 Revision of the NEC, appliance manufacturers were no longer permitted to bond the frame of an appliance over to the neutral, but you can bond the frame over to the neutral when retrofitting a old-style appliance whip to a new appliance.

If you have an older appliance and move into a home with a 4-wire dryer or range circuit, you will have to convert the appliance to a 4-wire appliance whip. Either conversion is easy to make, even for a DIY person who never attempted an electrical project before.

What you will need for this project.

  • The appropriate appliance whip

  • 1 – Phillips screwdriver

  • 1 – standard screwdriver

  • 1 – 3/8″ nutdriver

  • 1 – 5/16″ nutdriver

  • 1 – 1/4″ nutdriver

  • Wire Cutters

  • Wire Strippers

  • Long-Nose Pliers

  • A Short Length of AWG 10 Solid Copper Wire.

Typical Dryer Terminal Box Layout.

Refer back to this diagram as you read through the steps for converting from a 4-prong cable to a 3-prong cable and when converting from 3-prong cable to a 4-prong cable.

Switching a 4-prong dryer cord to a 3-prong dryer cord.

Make sure that they dryer is unplugged before starting to work on it.

This is the most common modification that you will have to make when buying a new appliance, if you live in or move into a home built prior to 1999.

As you can see in the above diagram, the terminal strip is laid out with the two hot wires, the Red and Black wires, connected to the two outside posts or screws, the ones labeled “L1” and “L2”. The “L1” and “L2” stand for “Line 1” and “Line 2”. The White Neutral wire always connects to the center terminal on the terminal strip, the terminal labeled “N” in this drawing. The terminals on the terminal strip on your dryer may be labeled with stick on labels (which may have fallen off) or with “L1”, “N”. and “L2” stamped in the metal. Whether the labels are still present and readable, the wires always connect in the same manner. It does not matter which outside terminal the red and black wires connect to as long as they are connected to the outside terminals.

Be careful when removing and replacing terminal screws, or the nuts in the case of terminal posts, to not drop them down inside the dryer because getting them out without disassembling the dryer can be next to impossible.

In the diagram above you will also see that the grounding wire, the yellow, green, or sometime bare wire, is connected to a green grounding screw that screws into the dryers metal frame.

To make the switch from the 4-prong appliance whip to the 3-prong appliance whip, do the following:

  • Remove the four conductor cord from the dryer.

  • Cut a short length of wire as a bonding wire.

  • Remove ¾ to 1-inch of insulation from the ends of the bonding wire, forming loops in the stripped ends with the long-nose pliers.

  • Place one of the loops around the green grounding screw in a clockwise direction and tighten the screw down on it.

  • Place the other looped end around the “Neutral” terminal screw or post on the terminal strip, also in a right-hand or clockwise direction.

  • Now install the three wire cord on the dryer—the red and black wires to the outside terminals and the white wire to the center terminal.

Converting a 3-wire to a 4-wire appliance whip.

The procedure is almost the same except in this case you remove and discard the brass bonding strap that bonded the frame to the neutral terminal on the terminal strip, isolating the neutral from the frame. Connect the grounding wire on the 4-wire whip to the frame.

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