What is Megger Testing?


When working with high-voltage cables that need quality insulation, you want to ensure that you have the best materials in place. One of the best ways you can do this is with the help of a Megger test. What is Megger testing, you might ask? Megger test equipment measures the electrical resistance and overall condition of your thermal insulation materials. Are you ready to put your materials to the Megger test? Learn how to read a Megger test result with the experts at Gateway Cable Company, as well as how to use the Megger tester properly.

What is a Megger Test?

If you have noticed faulty circuits or unstable currents coming from your electrical cables, this can surely be due to the mechanical stress your insulation endures. Which is why you need a Megger tester. But what is a Megger test? The purpose of Megger test equipment for cables is to measure the integrity of your insulation in megaohms, similar to an ohmmeter. The device itself consists of three essential components such as an alligator clip, an analog or digital meter, and a small button that generates a test current.

How to Use The Megger Tester

When it comes to figuring out how to use the Megger tester, it’s actually just a few simple steps! The Megger test will help you determine whether or not it’s time to replace your insulation by taking the following steps:

  1. Turn off your circuit breaker or unplug power to your device.
  2. Find a connection point to the wire or cable you want to test that is exposed to conductors.
  3. Put the alligator clip to the wire or cable and place the other meter probe to the exposed conductor. And press the test button.
  4. The Megger will generate a test current that should last 30 to 60 seconds in order to properly record the resistance of the jacket to the flow of the current.
  5. Once the test current is over, you’ll have your results.

How to Read Megger Test Results

The purpose of a Megger test is to determine whether or not your cables have the strength to perform a particular function or job. Once you’ve tested your wire or cables, you’ll have to know how to read Megger test results and what they mean.

In order for you to get the best insulation resistance for your electrical cables, you want to ensure that you’re getting 1 megohm per 1,000 volts of electricity. So, when you’ve conducted your Megger test, you’ll want your device to read between 35 and 100 megohms. If your reading is below that range, there’s likely an issue with your cable that will negatively affect its performance.

Cable insulation can degrade over time due to:

  • Prolonged use
  • Environmental exposure
  • Stress and mechanical damage
  • Excessive vibration
  • Contamination from dirt, oil, etc.
  • And other factors

Once the insulation is compromised, it will no longer be able to withstand current at a safe, reliable rate. If your wire does not get a proper reading, it should be replaced.

The Pros & Cons of Megger Testers


  • They can be used to test a wide variety of electrical equipment.
  • They are relatively easy to use.
  • They are a reliable way to test the insulation of electrical equipment.


  • They can be dangerous if not used properly.
  • They can be expensive.
  • They can be difficult to transport.

Overall, Megger testers are a valuable tool for electrical engineers and technicians. They can be used to test the insulation of electrical equipment and prevent electrical fires.

Discover More Electrical Tips at Gateway Cable Company

Now that you know what is a Megger tester, how to use a Megger tester, as well as how to read Megger test results, prepare for your next project with supplies from Gateway Cable Company. We offer a huge stock of connectors, adaptors, and cables for sale so you can find the right component to complete your work. Don’t see what you’re looking for online? Request a quote from the comfort of your home and we’ll have it ready for you! Contact us today for more information or speak with an electrical professional who can answer your questions!