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What is a megger test?

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Answered 2013-06-21 11:52:44
  • If you are referring to a megohm meter, it is a test of the insulation properties of such things as electric wiring, motor windings and high power antenna mounts.

    We use a "megger" or "meg out" electrical wiring and equipment to see if it is shorted to ground in any way.

    The megger uses much higher voltages to check resistance than a normal Volt-ohm meter.

    Ideally, you want infinity resistance but I've installed 460 volt motors with 750 meg ohms resistance to ground and had no problem.

  • On the whole megger testing is non destructive. What happens is a DC voltage is applied to the device or winding under test. It is an insulation test to see is the insulation has been injured in any way to cause a short circuit when normal power is applied to it.

    On my megger there are 3 ranges 300V, 750V, and 1000 volts. Applying the proper voltage is essential to not damaging the device you are testing.

    Working voltages up to 240 volts should use the 300 range.

    Working voltages up to 600 volts use the 750 volt range and working voltages above 600 use the 1000 volt range.

    As you can see if you used the 1000 volt range on a device that had a working voltage of say 24 volts you could damage the insulation just by testing it. So meggering a device is non destructive if you use the tester as its instructions tell you to.


As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.

Before you do any work yourself,

on electrical circuits, equipment or appliances,

always use a test meter to ensure the circuit is, in fact, de-energized.




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Related Questions

How is insulation test is performed on megger?

An insulation test is not performed on a megger, but using a megger.

What is the number of a megger test to shoot for?

A good number on a megger test should be around 2 megohms.

What is the importance of Megger test?

Megger tests are important because the test makes sure that your electrical insulation is safe and operating as intended. Megger tests are performed using a Meg-ohmmeter.

Can you megger or test an rcd?


What is the g in a megger test?

It is the terminal on the megger that the ground cable connect to when testing a device to ground.

How do you do megger test on instrument cables?


What is the output voltage of an insulation tester which is required to test a 230v circuit?

On a hand crank megger which is used to test insulation breakdown, use the 300V setting. If the megger does not have that setting use 500V as opposed to 1000V for the test. The output of the megger is a DC voltage.

What is the procedure to do a megger test on a generator?

The megger test on a generator is usually done to check the insulation factor of a generator. The high voltage is usually used to test the insulation system of a the generator in question. It is recommended to do this test after every six months.

What is generated voltage in megger?

The megger is used to find insulation resistance in any equipement. It will generate around 10kVA power to test.

What type of voltage applied during megger test?


What is the minimum resistance between phasea in megger test?


How much time duration is required while Meggar test is applied?

The time duration for a megger test is as long as it takes to turn the handle of the megger about five times. Voltage is generated on the first turn and if there is an insulation breakdown on the device being tested it will show instantaneously. If the megger is an electronic megger hold the generate button down for about three seconds.

What happens if a megger test fails?

If a megger test fails you have a short between the two wires or the wire to ground that you are testing. This short circuit has to be repaired before the equipment is placed back into service.

How do you test motor for burn?

To test a motor, use a megger (megohm meter) to test the insulation of the internal motor windings. Select a voltage to apply to the motor using an output from the megger that is higher that the operating voltage that the motor operates on.

How do you megger test continuity on a basic lighting circuit city and guilds level 2?

You don't megger test continuity. You test for that with a continuity meter or ohmmeter. "Meggers", as they're often called, produce high voltages to test the integrity of a conductor's insulation.

What value of tester is to be used for measuring insulation resistance of three phase 600V cables?

The typical test equipment for this is a megger. The megger is connected to two conductors at a time to test the insulation between the two.

Why do a megger test?

A megger test is done to check the insulation factor of wires or devices. This is to make sure that when the working voltage is applied, a short circuit to ground will not occur due to a problem with the insulation of the device or wire.

How do you test for short circuit?

You usually megger the device or cable with a megohm meter.

How do you test the insulation resistance using a megger?

See Discuss Question below.

What is allowable resistance of the cable in mergers test?

A good number on a megger test should be around 2 megohms.

What do megger measure?

Megger is usually short for Mega Ohm Meter. It measures high values of resistance with good accuracy. Most often used to test insulation.

What size of wire need to test using megger?

A megger is used to test insulation values. It doesn't have to be wire only. Any device that has electricity flowing through it can have its electrical insulation properties checked to see if there is any current leakage to ground. So to answer your question any size wire's insulation can be megger tested.

Why you use DC in megger?

There are different types of megger, which is simply a trade name for a range of different instruments. Not all meggers use d.c., for example, an earth-resistance megger uses a.c. On the other hand, an insulation-resistance megger uses d.c. because it applies a constant test voltage across the insulation being tested.

What is the accepted value for megger of 500 kv Ct tested by 5 KV DC Megger?

The value of insulation resistance varies according to the type of CT and manufacturer. It is best to check with the manufacturer for acceptable values. The word 'Megger' is a registered trademark of Megger Limited. Megger Limited's product range includes insulation testers, relay testers, battery testers and many other electrical test and measurement products. Tony Wills, Applications Engineer, Megger Ltd.

Conduct electrical megger test. what would be the minimum readings you would expect?