Converting from 4 prong cord to 3 prong due to moving to older house. Not sure what to do about grounding the middle terminal. I'm clear how to wire up the three wires on the cord. Just not sure if grounding to chassis is needed. If so how?

Green wire in 4 prong cord is a ground wire. It goes to ground screw that is separate from terminal block, usually right beside electrical opening.

Unplug the dryer then remove the terminal block cover and disconnect the 3-prong cord from the dryer. Note that the cord has red , black, and white wires but sometimes the red and black wires are both replaced by same color wire, usually gray and can switch places. There's also a ground strap wire also connected to the center terminal together with the white (neutral) wire.

Get yourself a 4-prong cord and note that it has red, black, white, and green/yellow wires but sometimes, like the 3-pronged one, the red and black wires are both replaced by same color wire, usually gray and can also switch places. All you have to do now is connect the 3 wires in the same manner they are connected as 3-prong cord to the terminal block. The ground strap wire now just need to be connected to the remaining 4th wire, the green/yellow wire instead of the center terminal together with the white (neutral) wire. Reinstall the terminal block cover and it's done.

It can be observed that converting a 3-prong cord to 4-prong cord is merely splitting the neutral line and the ground thereby increasing the number of prongs from 3 to 4 whereas, on the other hand, converting a 4-prong cord to 3-prong cord is merely joining the neutral line (white) and the ground (green/yellow) thereby reducing the number of prongs from 4 to 3.. The links below might enlighten you further on this matter.

Four-prong to Three-prong Electric Dryer Conversion
Three-prong to Four-prong Electric Dryer Conversion

It's either you convert the 3-prong outlet to 4-prong or the 4-prong cord to 3-prong. But the latter is easier and more feasible. Unplug the dryer then disconnect the 4-prong cord from the dryer. Note that it has red, black, white, and green/yellow wires but sometimes the red and black wires are both replaced by same color wire, usually gray. The red and black wires are lines L1 and L2 reversibly, meaning they can switch places, while the white and green/yellow wires are the neutral line and ground, respectively.

Get yourself a 3-prong cord and note that it has red , black, and white wires but sometimes, like the 4-pronged one, the red and black wires are both replaced by same color wire, usually gray and can also switch places. All you have to do now is connect these 3 wires in the same manner they are connected as 4-prong cord to the terminal block. The wire strapped to the dryer cabinet and connected to the green/yellow wire of the 4-prong cord wire is now left hanging. The last step is to connect this hanging strap wire to the same terminal on the terminal block (center) where the white wire (neutral) is connected and it's done.

It can be observed that converting a 4-prong cord to 3-prong cord is merely joining the neutral line (white) and the ground (green/yellow) thereby reducing the number of prongs from 4 to 3. On the other hand, converting a 3-prong cord to 4-prong cord is merely splitting the neutral line and the ground thereby increasing the number of prongs from 3 to 4. The link below might enlighten you further on this matter.

Electric Dryer Prong Conversion

Hi,
Here is a tip that will help you with changing your dryer plug. Dryer Cord and Wiring Dryer 3 Wire or 4 Wire



heatman101

There's a ground strap wire (green/yellow) attached to the dryer cabinet and connected to the center terminal where the white neutral wire of the power cord is connected. Disconnect this ground strap wire and remove the 3-prong power cord from the terminal block taking note where the wires are connecedt to. Connect the 4-prong power cord in the same way same wire colors of the 3-prong cord are connected to the terminal block. Connect the ground strap wire to the remaining fourth wire (green/yellow). Just do the reverse when converting 4-prong to 3-prong. The link below might enlighten you further on this matter.

Electric Dryer Prong Conversion

This advice is on how to correctly install an ELECTRIC DRYER or ELECTRIC RANGE 220-240VAC power cord (US Standards).

3-Prong or 4-Prong – The Difference:

3-prong color code:

BLACK (HOT – 110-120VAC) – May also be referred to as L1
RED (HOT – 110-120VAC) – May also be referred to as L2
WHITE (NEUTRAL – 0VAC) – Usually grounded to the equipment frame via a jumper wire or metal strap.

4-prong color code:

BLACK (HOT – 110-120VAC) – May also be referred to as L1
RED (HOT – 110-120VAC) – May also be referred to as L2
WHITE (NEUTRAL – 0VAC) – DO NOT ground to equipment frame.
GREEN (GROUND) – Attach to equipment frame.

Which One to Use: According to the National Electrical Code (NEC), Article 250, installations after the year 2000, require the use of a 4-prong plug which incorporates a separate ground and neutral wire. If you currently have a home that uses the 3-prong receptacle and cord, you can continue to use it. You will have to upgrade to a 4-prong configuration, however, if you plan on relocating your current receptacle, or if the internal wires of the receptacle become damaged in any way and require repair.

Converting from 3-prong to 4-prong: Make sure you UNPLUG the appliance prior to any repairs. CAUTION: Voltages dangerous to life are still present even with the appliance turned off and still plugged in. Notably in the area of the terminal block where the power cords are installed. You will need to remove the old cord by following these steps:

1. With the appliance UNPLUGGED, remove the access panel on the back of the unit where the power cord enters.
2. With the cover removed, you will see a terminal block where the power cord is attached. The terminal wires will be colored with the WHITE wire in the middle, and the BLACK and RED wires on either end. NOTE: There should be a green jumper wire or metal bonding strap attached to the NEUTRAL (white) terminal wire.
3. Remove the terminal lugs holding the old power cord wires in place. CAUTION: Use care not to drop any nuts or screws inside the appliance.
4. Remove the bonding strap or ground wire from the Neutral terminal lug. NOTE: If disconnecting a ground wire, make sure you re-attach it to the appliance frame.
5. Loosen the screws on the strain relief connector that holds the power cord in place and remove old power cord. NOTE: If your appliance does not have a strain relief that clamps down and hold the power cord in place, it is highly recommended that you install one. This prevents chaffing of the power cord against the appliance casing, and prevents the terminal wires from being pulled and broken loose. This could pose a potential shock hazard or cause damage to the appliance.
6. Install new power cord by threading it through the strain relief connector and tighten down the screws.
7. Connect the new power cord to the corresponding colors at the terminal block (Black goes to Black, Red goes to Red, White goes to White). The difference is going to be a Green (ground) wire that will connect to the appliance frame. There’s usually a green grounding screw for this. NOTE: If you disconnected a green grounding strap in Step 4., you can connect these two wires at the same point.
8. Re-install access cover. Turn off the service breaker to the appliance PRIOR to plugging it back in. With the breaker in the off position, plug the appliance in, and THEN turn the breaker on. In the event, something was wired incorrectly, it is far better to have your hands away from the receptacle and controlled from a distance. Safety first.

These steps will work for nearly all appliances that require a 220-240VAC power cord conversion. The power cords are usually rated at 250VAC, 30 amps, and are carried by any hardware store or appliance parts retailer.

ADDITIONAL NOTES:

1. If you desire to convert an appliance from a 4-prong to a 3-prong, make sure you reconnect the bonding strap and/or ground wire to the Neutral (white) wire at the terminal block.
2. On some newer appliances, it is REQUIRED that you use a 4-prong plug in order for the timer or clock circuits to function properly due to the way they are configured. Refer to your owner’s manual for the correct recommendation. Even if you currently have a 3-prong receptacle, you still may be required to upgrade to a 4-prong if you encounter this situation.
3. In many circumstances, new appliances are NOT sold with the power cord due to the various power configurations in homes. Always refer to the contents description on the shipping container the appliance comes with to see what additional items or tools may be required for installation.

If converting from a 4-prong to a 3-prong configuration, the wires are terminated at the terminal block as follows:

RED (hot) - to RED
BLACK (hot) - to BLACK
WHITE (neutral) - to WHITE
GREEN (ground) - is terminated to neutral by using a common screw at the terminal block, or by using a ground strap from the neutral terminal to a ground on the equipment casing.

If in doubt, the following link explains the color codes:

http://www.fixya.com/support/r793520-3_prong_4_prong_power_cord_conversion

If you have any questions, please ask me. I hope this helps you.

3-Prong or 4-Prong – The Difference:

3-prong color code:

BLACK (HOT – 110-120VAC) – May also be referred to as L1
RED (HOT – 110-120VAC) – May also be referred to as L2
WHITE (NEUTRAL – 0VAC) – Usually grounded to the equipment frame via a jumper wire or metal strap.

4-prong color code:

BLACK (HOT – 110-120VAC) – May also be referred to as L1
RED (HOT – 110-120VAC) – May also be referred to as L2
WHITE (NEUTRAL – 0VAC) – DO NOT ground to equipment frame.
GREEN (GROUND) – Attach to equipment frame.

Which One to Use: According to the National Electrical Code (NEC), Article 250, installations after the year 2000, require the use of a 4-prong plug which incorporates a separate ground and neutral wire. If you currently have a home that uses the 3-prong receptacle and cord, you can continue to use it. You will have to upgrade to a 4-prong configuration, however, if you plan on relocating your current receptacle, or if the internal wires of the receptacle become damaged in any way and require repair.

Converting from 3-prong to 4-prong: Make sure you UNPLUG the appliance prior to any repairs. CAUTION: Voltages dangerous to life are still present even with the appliance turned off and still plugged in. Notably in the area of the terminal block where the power cords are installed. You will need to remove the old cord by following these steps:

1. With the appliance UNPLUGGED, remove the access panel on the back of the unit where the power cord enters.
2. With the cover removed, you will see a terminal block where the power cord is attached. The terminal wires will be colored with the WHITE wire in the middle, and the BLACK and RED wires on either end. NOTE: There should be a green jumper wire or metal bonding strap attached to the NEUTRAL (white) terminal wire.
3. Remove the terminal lugs holding the old power cord wires in place. CAUTION: Use care not to drop any nuts or screws inside the appliance.
4. Remove the bonding strap or ground wire from the Neutral terminal lug. NOTE: If disconnecting a ground wire, make sure you re-attach it to the appliance frame.
5. Loosen the screws on the strain relief connector that holds the power cord in place and remove old power cord. NOTE: If your appliance does not have a strain relief that clamps down and hold the power cord in place, it is highly recommended that you install one. This prevents chaffing of the power cord against the appliance casing, and prevents the terminal wires from being pulled and broken loose. This could pose a potential shock hazard or cause damage to the appliance.
6. Install new power cord by threading it through the strain relief connector and tighten down the screws.
7. Connect the new power cord to the corresponding colors at the terminal block (Black goes to Black, Red goes to Red, White goes to White). The difference is going to be a Green (ground) wire that will connect to the appliance frame. There’s usually a green grounding screw for this. NOTE: If you disconnected a green grounding strap in Step 4., you can connect these two wires at the same point.
8. Re-install access cover. Turn off the service breaker to the appliance PRIOR to plugging it back in. With the breaker in the off position, plug the appliance in, and THEN turn the breaker on. In the event, something was wired incorrectly, it is far better to have your hands away from the receptacle and controlled from a distance. Safety first.

These steps will work for nearly all appliances that require a 220-240VAC power cord conversion. The power cords are usually rated at 250VAC, 30 amps, and are carried by any hardware store or appliance parts retailer.

ADDITIONAL NOTES:

1. If you desire to convert an appliance from a 4-prong to a 3-prong, make sure you reconnect the bonding strap and/or ground wire to the Neutral (white) wire at the terminal block.
2. On some newer appliances, it is REQUIRED that you use a 4-prong plug in order for the timer or clock circuits to function properly due to the way they are configured. Refer to your owner’s manual for the correct recommendation. Even if you currently have a 3-prong receptacle, you still may be required to upgrade to a 4-prong if you encounter this situation.
3. In many circumstances, new appliances are NOT sold with the power cord due to the various power configurations in homes. Always refer to the contents description on the shipping container the appliance comes with to see what additional items or tools may be required for installation.

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