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How to Use a Megger to Test Wire [Explained]

The wires are important but the insulation on that wire is equally important. That’s why the megger test is important to keep track of the insulation of the wire.

How to use a megger to test wire?

Turn off all kinds of electrical connections to the wire you want to test. Find the uncovered conductors of the wire. Connect one of the noses of the megger to one end of the wire. Attach the other one on the other end and hit the test button. This will give you the reading you are looking for.

Confused? Don’t worry! We got a whole guide on this.

So let’s get started!

How a Megger is Used to Test Wire?

Because a cable insulation test is essentially a consistency test, the connection must be turned off. If you’re checking the wiring in a type of hardware, turn it off. If you can’t turn it off then disconnect it.

Look for the revealed conductors by finding the connecting point of the wire. Connect one of the megger’s noses to the wire using the alligator clip. Then connect the second clip to the other revealed conductor. Then press the test button.

This will make the device create a current between the sensors. And the meter will measure the jacket’s resistance to the electric current. To achieve an accurate measurement keep it connected for at least 30 to 60 seconds.

Resistance measurement of 35 to 100 megohms is ideal. Insulation resistance levels of 1 megohm per 1,000 volts of electricity are acceptable for electrical wires.

You may use a megger to collect periodic measurements and make a graph out of it. This can be helpful to keep track of the insulation’s overall performance. A descending line or curve shows that the insulation is deteriorating.

You may also want to do a megger test when you are upgrading an electrical outlet. So that you can proceed with caution.

The slope of the line or curve indicates how long the insulation will persist. This method of charting steady decline is a more viable tool than spot testing.

It’s good to keep your wires checked, you must take some precautions. There are some precautions you should take while testing.

Precautions for Megger Test

During a Megger test, you can damage your equipment or even get injured severely. So prioritize your safety first:

  1. Use megger for high resistance measures only. Such as insulation or checking two independent conductors on a cable.
  2. When rotating the level, make sure to not get in touch with the leads.
  3. Before starting the test or attaching the megger, turn the equipment off. Discharge the wire or equipment completely otherwise you may get shocked.
  4. Ideally, you should disconnect the equipment you are testing completely from the plug.

If you are looking for some safety gear then here are some recommended ones:

Product 1
Product 2

Now let’s check out some things you should keep in mind while doing the test.

Things to Remember

Even though the megger test is important, most households don’t need it. Because the insulation of electrical wires in households deteriorates very slowly. So in the lifetime of the house, the wires won’t need testing.

But for handy technicians or even normal people, a megger can be used. It is easy to use and can be handy trying to find faults in household equipment.

Why is Megger Testing Needed?

Megger is used to test the insulation resistance quality of a wire. It’s primarily because of safety purposes. The insulation resistance might worsen day by day due to various factors. For instance, if a plug is hard to plug-in it may get faulty over time.

Factors like humidity, dust, temperature, moisture, etc affect insulation resistance quality over time. It is also significantly correlated with the presence of mechanical and electrical stress.

Thus checking the insulation resistance of equipment at a consistent regular period has become very important. It’s necessary to avoid any measure of lethal or electrical shock.

It is also very important after doing any kind of electrical work. You can understand if you have damaged any wiring or made any mistake using a megger.

Megger testing is also safe and does not damage your wiring. So you can keep your electrical system tested all the time.

But it’s also very common for kitchen wires to get damaged by stove heat. So it’s ideal if you keep some distance from your electrical outlet to the gas line.


Question: What are the benefits of megger testing?

Answer: It has a lot of benefits. You can be aware of your equipment’s condition by analyzing the readings. Also, It reduces the risk of electrical system failure.

Question: Are there different types of megger tests?

Answer: Yes. There are two types of megger tests. Electronic type and manual type are the two different types of megger test. And both have their own set of advantages and disadvantages.

Question: Should I use any safety equipment?

Answer: It’s better to use safety equipment while testing, but it’s not mandatory. Megger testing is quite safe because of low voltage. But using safety equipment is never a bad idea.


This article comes to an end here. We hope that now you know how to use a megger to test wire. But remember that it’s risky to handle electricity.

So if you are unsure about your technical abilities then do contact a professional.

See you in the next article!