How to Convert a 4-Prong Dryer Cord to Fit a 3-Slot Outlet

Project Overview
  • Total Time: 30 mins - 1 hr
  • Yield: Convert one 4-prong dryer cord to fit a 3-slot outlet
  • Skill Level: Intermediate
  • Estimated Cost: $10 to $30

When moving a newer electric dryer into an older house, it's common to find that the dryer cord and plug don't fit the 240-volt dryer outlet. The dryer's plug has four prongs, yet the outlet only has three slots.

If you're a homeowner, you can switch out the four-prong cord for a three-prong cord—no electrician necessary. Some new dryers, in fact, don't include power cords at all, allowing consumers to buy the type of cord that matches their home's dryer outlet. What makes this an attractive solution for DIYers is that the dryer outlet never needs to be opened or worked on—only the dryer cord.

3 and 4 prong dryer cords on top of a dryer

The Spruce / Candace Madonna

Before You Begin

Before the mid-1990s, most electric clothes dryers operated with three-prong plugs that fit into three-slot outlets. Since 1996, the electric code has required four-slot outlets that accept only four-wire cords.

There are several workarounds for mismatched cords and outlets. Replacing the dryer cord is by far the easiest solution and the one that most DIYers pursue when they are faced with the problem.

While the four-prong and four-slot arrangement is considered to be an improvement, the electrical code allows you to replace the four-prong cord with a three-prong cord to match the outlet.

Safety Considerations

Even though you will be working on an unplugged dryer, it is best to be cautious and shut off the circuit powering the dryer before you unplug it or plug it back in.

Make sure that you attach a strain-relief clamp to the new cord. Because of dryers' high voltages and their tendency to move, it's important to secure the cord.

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What You'll Need

Equipment / Tools

  • Voltage tester
  • Pliers
  • Magnetic nut driver
  • Screwdrivers

Materials

  • UL-listed three-prong dryer cord with strain-relief clamp

Instructions

Materials and tools to change a 4-prong dryer cord to fit a 3-slot outlet

The Spruce / Kevin Norris

  1. Shut Off the Breaker

    Unplug the dryer. In the main service panel (breaker box), find the double-pole circuit breaker that controls the clothes dryer and flip the breaker to the OFF position.

    Most dryer circuits have 30-amp breakers, indicated by a "30" stamped on the switch bar of the breaker. A double-pole breaker is twice as wide as a standard (single-pole) breaker, and most service panels have only a few double-pole breakers.

    Circuit breaker shutting off power in service panel

    The Spruce / Kevin Norris

  2. Check For Power

    At the dryer outlet, check for power using a non-contact voltage tester. Rotate the dryer to a position where you have access to the back panel. Disconnect the dryer vent to move and work on the dryer.

    Clothes dryer plug being checked for power with non-contact voltage tester

    The Spruce / Kevin Norris

  3. Remove the Dryer's Electrical Connection Cover

    Use a screwdriver to remove the cover on the electrical connection box on the back of the dryer. The box is located just above where the power cord comes out of the dryer and is attached with one or two screws. Set the cover and screws aside.

    Removing the electrical connection box cover on the back of the dryer with a screwdriver

    The Spruce / Kevin Norris

  4. Detach the Four-Prong Cord

    Remove the strain-relief clamp holding the cord by removing the two screws that join the two halves of the clamp together. Separate the halves of the fitting and pull them out of the hole individually.

    Using a magnetic nut driver or screwdriver, disconnect the black and red cord wires from the left-side and right-side terminals on the dryer's terminal block. These are the hot wire connections. Disconnect the white wire from the center terminal. Disconnect the green grounding wire from the machine case by unscrewing the green grounding screw.

    Slide the four-prong cord out of the connection box.

    Screwdriver disconnecting black and red wires on dryer's terminal block to detach electrical cord

    The Spruce / Kevin Norris

  5. Jump the Neutral to the Ground

    For a three-prong cord to work correctly, you must connect the dryer's neutral terminal to the case ground with a jumper.

    Locate the white machine wire that is connected to the neutral (center) screw terminal. Disconnect it and reconnect it under the green grounding screw. Tighten the screw firmly.

    Alternatively, the dryer may have a metal bonding strap (typically connected under the ground screw) instead of a white machine wire. If so, attach the strap to both the ground screw and the neutral (center) terminal.

    Dryer's white machine wire screwed firmly to green grounding screw

    The Spruce / Kevin Norris

  6. Connect the Three-Prong Cord

    Thread the loose end of the three-prong cord through the hole in the electrical connection box. Connect the outer two wires (the hot wires) on the cord to the outer two screw terminals on the dryer, one on each screw. Connect the center wire to the center (neutral) terminal.

    If there is a bonding strap for the ground, it must be connected to the neutral terminal along with the center cord wire.

    Tighten all wire connections firmly.

    Screwdriver securing wires through three-prong cord in electrical connection box

    The Spruce / Kevin Norris

  7. Install the New Strain-Relief Clamp

    Slide one-half of the strain-relief clamp into the hole under the cord wire. Fit the other half of the clamp in the same way but on the top of the cord. Squeeze the two halves together with pliers and thread the screws into the holes. Tighten the screws until the cord is secure.

    Warning

    Do not reuse the original strain-relief clamp with the new three-prong cord. Clamps for four-prong cords are round and will not properly fit the flat shape of a three-prong cord. Use the strain-relief clamp that comes with the new cord, or buy a compatible clamp separately.

    Strain-relief clamp secured around cord wires with screwdriver

    The Spruce / Kevin Norris

  8. Plug in the Dryer

    Reattach the connection box cover plate with its screw(s). Slide the dryer into place, and reconnect the dryer vent duct, if necessary. Plug the cord into the outlet. At the main service panel, turn the dryer's circuit breaker back to the ON position, then test the dryer for proper operation.

    Clothes dryer plug inserted into wall outlet

    The Spruce / Kevin Norris

When to Call a Professional

Though converting a 4-prong plug into a 3-prong plug should be within the skill set of most intermediate-level DIYers, call an electrician to do the job if you're not comfortable doing the work.

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  1. Dryers Safety Information. General Electric