The first step in how to wire a dryer is to review your electrical configuration. Electric dryers typically require a dedicated 30-amp, 240-volt breaker. The wire supplying power from the breaker panel to your dryer outlet will usually be a 10/3 Romex cable (Blk wire- hot, Red wire – hot, White wire – neutral, Bare copper wire – ground).
New dryers do not come with a power cord. That's because until recently, homes were wired with two different receptacle styles: 3-prong and 4-prong. Knowing that homes had a variety of outlet types, it didn't make sense for appliance manufactures to pre-wire the stove with one or the other. The 4-prong plug adds a safety ground wire in addition to the two hots and neutral found on the 3-prong plug. Below are pictures of both a 3-prong and 4-prong style outlets with respective labeling. With a voltmeter you can check for proper voltage on the wall outlet before plugging in your appliance. You should measure 220-240VAC between lines (hots), and half of that voltage if you measure between either of the hots to neutral. If you are wondering how to wire a dryer with a 4 prong plug but you have a 3 prong wall receptacle you have a couple of options. One is to upgrade the wall receptacle to a 4 prong receptacle. Hopefully there is a ground wire already to the electrical box. otherwise this option will not work. The second option is the leave the 3 prong wall receptacle as is and purchase a 3 prong cord for your new dryer. Most dryers will accommodate this configuration as they know a lot of people still have the 3 prong receptacles in their homes that they must make work.
If wiring a newer dryer into an older home, containing a 3-wire outlet, you can do so with the diagram to the left. The dryer will need to have a copper grounding strap between neutral and the green grounding screw. The grounding screw will connect directly to the dryer chassis or frame. The hots (black and red) are connected as shown and the neutral wire gets tied to the center lug.
Instructions on How to wire a Dryer:
The following instructions cover how to wire a dryer with a 3 prong cord:
Another option would be to upgrade the 3-prong outlet in your house to a 4-prong. Once you do that, you can follow the 4-wire hook shown below.
History of 3-wire vs. 4-wire dryer wiring:
In all houses the neutral wire and the ground wires are connected together. but ONLY at the main panel.
Not long ago houses were being built with a 3-prong dryer receptacle, while mobile homes were required to have a 4-prong receptacle. The 4-prong receptacle has a separate prong for the ground wire, the 3-prong receptacle either didn't use the ground, or the ground was tied together with the neutral.
With the 1996 National Electrical Code revision they stopped allowing this loophole in an otherwise sensible wiring system. Now all dryers (and electric ranges) must be wired with a 4-prong outlet.
It is very easy to understand why many people get confused when attempting to install an electric dryer. For starters, the heavy cable used on an electric dryer may have three or four heavy wires. Since 2000, electrical code states that four wires are required. For many people fooling with these heavy wires is very intimidating. The wires are heavy gauge because the dryer heating element draws 15 Amps. Normal lamp cord wiring will get hot and melt. I have seen many novices cause a lot of trouble by mixing heavy and light gauges. Most folks are frightened away by the heavy wires and leave the job to appliance technicians or electricians.
Many different situations are encountered. If a person moves an old dryer to a new house they may be faced with an old three-prong line cord on the dryer and a four-prong outlet.
Second, a new dryer does not come with a line cord. Often a retailer will sell the customer a four-prong cord (The current code). When they get home, they find that their house has a three-prong outlet and they don’t know what to do. Of course, they are irritated because they thought all they had to do was plug it in and start drying clothes. I must admit that fewer and fewer homeowners attempt to connect up anything involving 220 V. It scares them to death. However, this post will explain the logic behind the national code changes and how to handle these situations.
First, let’s review a bit of history. When electric dryers first came out 60-70 years ago they were all hardwired to the house (no cords were made back then). The cable used was 10-3 with the ground. It included four wires. Three of the wires were 10 gauge a black, white and red. The fourth wire was 12 gauge, bare copper.
The three colored wires were attached to the terminal block on the back of the dryer with the white wire going to the center. The bare copper wire was screwed to the metal frame or shell or the dryer. The red and black are interchangeable but typically the red is connected to the right-hand side of the block. Nothing could be simpler. It was hard to get it wrong. The white wire and the bare ground wire parallel one another back to the panel box and are connected together and to the earth. The neutral wire carries minimal current while the red and black carry the heater circuit. The bare ground wire carries no current and it’s purely a safety circuit.
As the years went by new homes were built with a dryer outlet already installed in the wall and three-prong line cords were made available to connect the dryer to the heavy outlet. These line cords were three wire only and did not include the bare wire.
A cautious electrician or homeowner would add a bare wire, a ground wire, from the case of the dryer to the metal case of the outlet or a water pipe. This insured that the metal case of the dryer was directly connected to the earth ground through the electrical system of the house. By doing so it was impossible to get a shock by touching the dryer.
A grounding strap was added next to the terminal block inside the dryer connecting the center tab (the white one) to the chassis metal of the dryer. This was the second way of ensuring that the metal case was connected to earth because the white center wire is connected to the earth back at the panel box. All of these shenanigans are in place to prevent or dissipate any voltage from appearing on the case of the dryer thus preventing electrocution.
With the advent of the extra-safe four-wire heavy line cord the missing bare ground wire from decades gone by has reappeared within the line cord. It is the fourth wire and color-coded green. This green wire is to be connected to the chassis or case of the dryer. The grounding strap within the dryer (supplied by the manufacturer) is removed. The new green wire takes it place.
Back at the panel box the green wires, any bare copper wires, the white center neutral wire are all connected together and directly connected to the utility ground and also to a heavy copper rod that is driven into the earth.
Back to the problem at hand, it is far easier to change the line cord then it is to change the socket.
Consequently, match your line cord prongs to the socket holes and by a line cord that fits.
Wire the matching cord as shown here.
If you can handle connecting dryer line cords and outlets you surely have the aptitude for making money with your skills. Learn from UncleHarry.com as I did and start making yourself $100,000 per year. Ask to try out some of his free sample courses. It is a great way to make a living with minimal start-up costs.
2 Replies to “How to Wire a Three or Four Wire Dryer Outlet”
Can a 220 circuit function safely with no separate neutral. In other words, with 2 110’s and a ground?
Each of your 110VAC circuits already has a neutral wire. However it’s more complicated than that as what you are are doing is not code nor safe. You must be connected to a 220VAC breaker to get both sides of the incoming 220VAC to the house. Get an electrician!
3-Prong Dryer Outlet
The 3 prong wiring diagram above shows the proper connections for both ends of the circuit. This circuit originates from the breaker box containing a 2-pole 30 Amp breaker. This size breaker requires a minimum of a #10 gauge wire so this wire used would be a 10/2 with ground.
Now a 3-prong outlet is outdated from modern electrical codes but is accepted if you already have one in your home. If your running a new circuit, I highly recommend that you bring your outlet up to code and install a 4-prong dryer outlet. (See Below)
The difference between this diagram and the 4-prong outlet below is the addition of a neutral wire. The neutral line is a return line for the voltage and should not be done through the green ground wire, even though a neutral and ground are really the same, so new codes require a dedicated neutral line as well as a dedicated ground line. This just simply separates the ground circuit and neutral circuit versus having the ground line act as a neutral in the older circuit above.
Clear as mud right,
4-Prong Dryer Outlet
(Yellow Wire = White)
The 4-prong dryer outlet wiring diagram above is ran with a 10/3 with ground cable.
As you can see, there is now an added dedicated neutral. The ground is now a dedicated wire also. But if you notice, both the neutral and the ground wires both connect to the same ground bar inside the panel box. As mentioned earlier, the neutral and ground are really the same but this wiring method is more accurate because a return line or “grounded neutral” should be a white wire and not green.
Some panel or breaker boxes will have a dedicated neutral bar and a dedicated ground bar, but they will still be physically connected.
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4-Wire/Prong Electric Dryer Cord
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4-Wire/Prong Electric Dryer Cord
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4-Wire/Prong Electric Dryer Cord
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The 4-Wire/Prong Electric Dryer Cord is for use with most modern dryers post-2000 and supports between 250 and 7500 watts with color-coded prongs for easy installation.
- Model #: 90-2020
- Stock #: 3792-000
- Bonus Features: 250V, 4 10 Gauge Wires, 4 FT Long
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