How To Change 3 Prong To 4 Prong Dryer Cord

How to change 3 prong to 4 prong dryer cord? This is an electrical question I receive a lot. In order to change the cord on your dryer, you need a 4-wire dryer cord.

The 1999 edition of the National Electrical Code® (NEC®) first introduced the requirement for a separate ground wire for ranges and dryers. This is also in the 2002 edition as well as the current 2022 edition.

Difference Between 3 Prong To 4 Prong Cord

The difference between 3 prong and 4 prong dryer cords is in the wiring configuration. The 3 prong cord has only two hot wires and one neutral wire, while the 4 prong cord has a separate ground wire.

The old configuration has no separate ground wire. The new 4 prong drier cord has the dryer’s neutral and ground are not connected together. If you want to change the 3 prong to the 4 prong dryer cord configuration, you must make sure that the dryer’s neutral terminal is not connected to the case ground. 

All dryer and range receptacles installed after 2000 are required to be the 4-wire type. This would require a 4-wire cord. All dryer and range receptacles installed before 2000 are the 3-wire types. If a 3-wire receptacle goes bad, you are permitted to install a new 3-wire receptacle.

However, if the cable for the 3-wire receptacle goes bad or if you change the location of your 3-wire receptacle, you are required to upgrade to the new and safer 4-wire type.

Dryers and ranges are not sold with a particular cord attached because of this requirement. When you purchase a new dryer, the appliance store will ask if you want a 3-wire or a 4-wire cord. Both cords are rated 250 volts and 30 amps, as are all household electric dryers.

How To Change Dryer Cord – Steps-by-Steps Guide

The tools you will need for this installation are:

  • 1 – phillips screwdriver
  • 1 – standard screwdriver
  • 1 – 3/8″ nut driver
  • 1 – 5/16″ nut driver
  • 1 – 1/4″ nut driver

To change your dryer cord from a 3-wire to a 4-wire, you first need to disconnect the old dryer cord. To do this, make sure your dryer is unplugged and open the access panel cover on the back of the dryer.

This cover is all different sizes and shapes depending on the manufacturer of the dryer, but it is typically very close to where the cord enters the dryer. The cover is typically held in place with 1 – 4 screws. See the image below of a dryer access panel.

dryer access panel

With the cover open, you will see a terminal block with three wires; black on one end, white in the middle and red on the other end.

Use your 3/8″ nut driver to remove the nuts or a phillips screwdriver to remove the bolts (depending on your dryer) and remove each dryer cord wire from the terminal block. When you remove the nuts or bolts, be careful not to drop them down into your dryer.

Now you need to disconnect the bonding jumper on your dryer. The bonding jumper is either a metallic strap (typically copper or copperclad) or a green wire that is connected between your dryer’s neutral (white wire) terminal and the green ground screw connected to your dryer’s frame.

the bonding jumper on your dryer

Removing this bonding jumper is an extremely important step when changing from a 3-wire to a 4-wire cord to prevent electrical shocks when touching anything metallic on your dryer.

If you removed a ground wire instead of a bonding strap from the neutral terminal, you need to connect this ground wire to your dryer’s frame.

Loosen the screws at the connector and pull the cord out. Now thread your new cord through the connector and tighten down. This only needs to be snug and not overtighten.

Sometimes the old connector will work with the new cord, and sometimes not. If not, your new cord will include a connector that you may use.

To hook up your new 4-wire dryer cord, connect each wire to the dryer’s terminal block matching color for color (white to white, black to black and red to red). Connect the green wire to the green ground screw on your dryer’s frame.

Replace the access panel cover, and your new 4-wire dryer cord is installed.

Before plugging in your new dryer cord, I recommend turning off the breaker to your dryer receptacle. Then plug in your dryer. Now turn the breaker back on.

This is not foolproof, but it is a safer way to turn on the power to your dryer if you made a mistake connecting your new dryer cord.

If your dryer is different from the one described above and you would like a second opinion on your connections, contact us with a picture of the terminal block. I will post the right answer on how to change 3 prong to 4 prong dryer cord to help others with the same dryer.

Conclusion

Changing 3 prong to 4 prong dryer cord isn’t easy task, it’s a job for a professional electrician. The better solution due to the National Electrical Codes changes is replacing the old dryer cord with one that’s compatible with the outlet.

Worked in IT for 10 years, specialising in computer measurement, resource and performance management and complex problem solving. Changed careers to HVACr in 2015.

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