3 prong dryer outlets are the old setup where there were two hot wires and a neutral wire. The grounding was unavailable. But in the 4 wire system we have the grounding wire set up. So, how to connect the 3 prong dryer into the 4 wire setup?

I think you have already guessed what I am going to say. While connecting the 3 prong dryer the grounding wire will be omitted. The two hot wires and the neutral will be connected to the 3 prong dryer outlet.

Be sure to check the power is off before working with an outlet. Using a tool like this fluke voltage detector to sense if voltage is still present at the outlet.

Let us have a broader look inside the topic.

How To Wire A 3 Prong Dryer Outlet To 4 Wire Install?

What Is A Dryer Cord And Outlet?

Dryer cord is a particular kind of power cord. It is used in the electric dryer or washing machine. The female port, in which the dryer cord is connected, is known as dryer outlet.

Types of Dryer cords:

There are mainly two types of dryer cords and outlets according to their number of prongs. They are:

  1. 3 prong dryer cord
  2. 3 prong dryer outlet
  3. 4 prong dryer cord
  4. 4 prong dryer outlet

What is a 3 prong dryer cord?

It is a type of dryer cord that has 3 prongs, that is 3 wires inside it. Two of them are hot wires and the third one is a neutral.

The outlet that holds a 3 prong dryer cord is known as a 3 prong outlet.

3 prong cord and outlet
Fig 2: 3 prong cord and outlet

What is a 4 prong dryer cord?

This type of dryer cord has 4 wires, so it has 4 prongs. Two of them are hot, one neutral and it has a grounded wire unlike the 3 prong cord.

Similarly, the outlet used to hold a 4 prong cord is known as 4 prong outlet.

4 prong cord and outlet
Fig 3: 4 prong cord and outlet

What Is The Technical Difference Between A 3 Prong And 4 Prong Dryer Install?

The presence of an extra ground wire is the main technical difference between the two types. The ground wire plays a significant role in assuring the safety of both the users and the electrical device. Why is it so important?

In 3 prong dryer install there is only one neutral. If, by any chance, there is damage in the neutral line or a loose connection, the device becomes a hazard. It cannot pass the current to the ground, thus the current passes through anyone who touches the device. The fourth wire solves this problem.

The addition of the fourth wire in the 4 prong dryer install, the current can pass through the ground wire in such cases. Thus it ensures safety.

Is It Safe To Use A 3 Prong Outlet?

It is not fully safe to use a 3 prong dryer. Because there are two hot wires and a neutral. So, the current travels back through the neutral to complete the circuit. But it has some limitations. Let me enlighten you with some facts about it.

The neutral is used to complete the circuit. Additionally, the body of the device used to be connected to the neutral. If there is any leakage current in the body it would pass through the neutral.

But the nature of the current is to pass through the least resistive path. Sometimes when the user touches the device with wet hands and bare foot, he gets conducted to the stored current in the body. This can lead to disasters.

To prevent such outcomes, a code was approved in the 1996 that all house electric designs should have a grounding wire. Thus the 4 prong dryer system was introduced. It contains a ground wire that is connected to the device body for the leakage currents.

Then Why Do We Need To Use A 3 Prong Dryer Outlet?

Earlier the dryer machines were designed with a 3 prong cord. So, the outlets used in homes and other places were also 3 prong. Later on, 4 prong outlets and devices took over the old model. But for the existence of the old models people often need 3 prong outlets.

In recent times, all houses’ electric design consists of a ground wire to ensure safety purposes. But before this, the electric setups were designed for 3 prong. Still many such devices are in existence. Due to which we need 3 prong dryer outlets.

How To Wire A 3 Prong Dryer Outlet To A 4 Wire Install?

To wire a 3 prong dryer you have to connect the two hot wires to the respective terminals of the outlet. The ground and neutral are joined together using a ground strap and then connected to the neutral terminal of the outlet.

Fig 4: Wiring a 3 prong outlet to a 4 wire install


Step 1: Power off the main switch of the outlet

Step 2: Open the outlet and loosen the screws of the terminals. You will see three terminals as shown in figure 4.

Step 3: Take the 4 wires and peel off the insulations from the edge of the wires

Step 4: Connect the red and black hot wires in the hot prongs of the outlet as shown in the figure.

Step 5: Connect a ground strap or jumper to the neutral terminal in the outlet.

Step 6: Connect the ground wire to the jumper and the neutral wire to the 3rd prong as shown in the figure

Alternative Procedure:

Keeping everything same you can skip connecting the ground wire. You can connect the ground to the steel body of the outlet. Before 1996 there was no ground wire in the electric designs of the house. People used to use the other 3 wires. But it is not a hundred percent safe practice.

What Safety Precautions to Take?

Electricity can bring hazard to us. So it is essential to take proper safety measures while working with it.

Make sure to keep your hands dry while working. Wear safety shoes. Turn off the breakers. Use testers to search for live lines before touching any bare wire.

Since 4 prong installs have two live wires, make sure to know which wires are the hot ones. Here, the black wire is not the neutral. It is the second hot wire.


Dryer outlets are upgraded and 4 prongs are the new generation now. But still, 3 prongs are used now and then for the old machines. The conversion between the two is an easy technique as you can see reading the article.

I hope if you have a 3 prong dryer machine, you can wire your own outlet now and be a hero for your family. Be careful while working. Good luck.

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