How to Test Ground with Multimeter (6-Step Guide)

For any electrical wiring system, having a ground wire is vital. Sometimes, not having a ground wire can cause disastrous outcomes for the whole circuit. That is why today, we look at how to test the ground with a multimeter.

In general, after setting the multimeter to the highest voltage settings, you can insert the probes to check hot, neutral, and ground wires and their voltages. Then you will be able to determine if the outlet is grounded correctly or not. We will go into more depth below.

What is Grounding?

Before we get into our testing process, we need to discuss the grounding. Without a proper understanding of the ground connection, moving forward is pointless. So, here is a simple explanation for grounding.

The primary purpose of a ground connection is to transmit discharged electricity from an appliance or outlet into the ground. Therefore, no one will get electrocuted because of the discharged electricity. For proper safety protocol having a working ground, wire is essential. You can use this process for your home or vehicle. (1)

6 Step Guide for Testing a Ground Wire with a Multimeter

In this section, we will discuss how to check the ground with a multimeter. Also, for this demonstration, we will use a typical house electrical outlet. The goal is to find if the outlet is grounded correctly or not. (2)

Step 1 – Set Up the Multimeter

multimeter tool
Video | Flashback502

First, you should set the multimeter properly for the testing process. So, set the multimeter to AC voltage mode. However, if you use an analog multimeter, you should adjust the dial to the letter V position.

On the other hand, if you are using a digital multimeter, you should navigate the settings until you find the AC Voltage. After you locate it, set the cutoff value for the highest voltage. Remember, setting up the highest voltage will help immensely in getting an accurate reading.

However, some multimeters come without cutoff values. If that is the case, set the multimeter to AC voltage settings and start the test.

Step 2 – Connect the Probes

multimeter tool 01
Video | Flashback502

You can find two different-colored probes in your multimeter, red and black. These two probes should connect properly to the multimeter ports. Therefore, attach the red probe to the port labeled as V, Ω, or +. Then, attach the black probe to the port labeled as – or COM. Messing up the connection of these two probes and ports can cause a short circuit situation in your multimeter.

Also, don’t use probes that are damaged or cracked. Furthermore, avoid using probes with exposed wires because you might get electrocuted while testing.

Step 3 – Check the Reading Using Live and Neutral Ports

multimeter socket testing
Video | Flashback502

Now you can check the ground wire using the multimeter. In this step, you have to test the hot and neutral wires with the multimeter probes.

Before doing that, make sure to hold the probes from the insulation wrappers, this will protect you from any shocks.

Then push the red probe inside the live port.

Take the black probe and push it into the neutral port. Usually, the smaller port is the live port, and the larger port is the neutral port.

“However, if you cannot identify the ports, you can always follow the traditional method. Bring out the three wires, and then with the different colors, you can easily understand the wires.

Usually, the live wire is brown, the neutral wire is blue, and the ground wire is yellow or green.”

After pushing the two probes inside the live and neutral ports, check the voltage on the multimeter and note it down.

Step 4 – Check the Voltage with the Earth Port

Now you should check the voltage between the live and earth ports. To do that, take out the red probe from the neutral port and carefully push it inside the earth port. Do not disconnect the black probe from the live port during this process. Earth port is a circular or U-shaped hole located at the bottom or top of the outlet.

Check the voltage reading on the multimeter and note it down. Now compare this reading with the earlier reading.

If the outlet’s connection is grounded, you will get a reading equal to or within 5V. However, if the reading between the live and earth port is zero or close to zero, that means the outlet is not grounded.

Step 5 – Compare All the Readings

ground testing using multimeter
Video | Flashback502

For proper comparison, you will need at least three readings. You already have two readings.

Reading One: Live and neutral port reading

Reading Two: Live and earth port reading

Now take the reading of the neutral port and earth port. To do this:

  1. Push the red probe inside of the neutral port.
  2. Push the black probe inside of the earth port.
  3. Note down the reading.

You will get a small reading for these two ports. However, if your house connection is not grounded, there is no need to take the third reading.

Step 6 – Calculate the Total Leakage

If you followed Steps 3,4, and 5, now you have three different readings. From these three readings, calculate the total leakage.

To find total leakage, subtract the first reading from the second reading. Then add the third reading to the resulted reading. If the final result is greater than 2V, you might be working with a faulty ground wire. If the result is less than 2V, the outlet is safe to use.

This is an excellent method to find faulty ground wires.

Automotive Electrical Ground Issues

For any vehicle, several electrical problems can occur due to bad electrical ground connections. Also, these issues might come in many forms such as noise in the audio system, fuel pump issues, or messed-up electronic engine controls. If you can avoid these issues, it will be great for you and your vehicle.

Here are some tips on how to prevent such a situation.

Quality Ground Point

Most of us think if somehow the ground wire contacts the vehicle, everything is grounded. But, this is not true. The ground wire should be properly attached to the vehicle. For instance, select a point that is free of paint and rust. Then make the connection.

Use a Multimeter to Check Ground

After attaching the ground wire, it is always better to check the ground connection. So, use a multimeter for this process. Use the battery and the ground wire to determine the voltages.

Use Larger Gauge Wires

Depending on the amount of current, you might have to change the gauge of the ground wire. Usually, factory-made wires have 10 to 12 gauges.

Below are some other multimeter learning guides that you can also check.






References
(1) get electrocuted – https://www.mayoclinic.org/first-aid/first-aid-electrical-shock/basics/art-20056695
(2) typical house – https://www.bhg.com/home-improvement/exteriors/curb-appeal/house-styles/

Video Reference

About Sam Orlovsky

b1d87d2ee85af3e51479df87928bdc88?s=90&d=mm&r=gI realized early on carpentry was a huge passion for me and I’ve stayed in the industry for over 20 years now. This gives me a unique ability to really be able to tell you what the best tools and recommendations are. I’m not only a carpenter but I also like machinery and anything to do with electrics. One of my career paths starting off was as an apprentice electrician so I also have a lot of experience with electrical products and anything related.