Megger Insulation Tester - Review

Table of contents

RoadTest: Megger Insulation Tester

Author: nontheist

Creation date:

Evaluation Type: Test Equipment

Did you receive all parts the manufacturer stated would be included in the package?: True

What other parts do you consider comparable to this product?: To a certain extent, standard multi-meters are also comparable to his product as most of the functionality is duplicated.

What were the biggest problems encountered?: I didn't have any problems.

Detailed Review:



There were no real surprises here.  The carrying case is enclosed in a small cardboard sleeve with a feature comparison chart versus other MIT 400 series models.  It's listed as an insulation and continuity tester but carries a number of other features I'm not used to seeing on an insulation tester (more on this later!).  To see the specs, see here:


Included in the package:

  • a very sturdy carrying case with two clasps
  • The Megger
  • Two standard leads
  • One lead with integrated 'test' button - more on that later
  • A disk with user guide and the e-book 'A Stitch in Time' - an excellent resource
  • A certification/calibration sheet (good for ~1 year)




Using the MIT420/2

The test lead ports are at the top of this unit.  It comes with a red lead and a black lead, exactly like you would expect.  There are interchangeable test lead tips for alligator clips or a pointed tip.  Included is also a 2nd red lead that includes an integrated 'test' push button.  The normal method for using this megger is to attach your leads and then push the yellow test button.  To lock in the test you'd press the yellow test followed by the red lock button.  You can also use the pre-programmed polarization index test or dielectric absorption ratio.  If you need a 'quick' test in a tight area the included red lead with 'test' push button would be very useful for you.  This lead allows you to perform a test without having to push the yellow button on the main unit.


This unit has what is called 'Stabilised insulation test voltage', so you can be sure that your tests are as accurate as possible (2% voltage vs. 10-20% for other insulation testers).  During my use the voltage approached the test voltage and didn't have any overshoot. My use case doesn't require that much accuracy but it is a feature worth mentioning.


The main unit has a very rugged feel.  The grey body has a very slight rubberized feel and is very easy to keep your grip.  During my first week of use, I was tasked with testing a very oil leak prone air compressor.  It was impossible to keep from having to set this Megger in some oil.  This unit handled the oil like a champ.  Most of the other types of testers I have end up discolored due to the abuse that we inflict on them but this tester cleaned right up.  It has an IP54 weatherproof rating as well. I didn't have any rain during my testing and I'd rather not have to try to megger a motor in the rain but if I had to, this would be the unit I'd bring along.


The screen has optional backlighting which is surprisingly bright.  The text is large and clear and the light is a white/blue when backlit.  Too many of our industrial areas suffer from poor lighting.  I have a 'yellow' brand tester that doesn't include a backlight.  It's one of those features that you didn't realize you wanted until you needed it. 


Test results can be stored on internal memory on a per-register basis.  (i.e. first test goes in register 1.  next test is in register 2).  Navigation is very straight forward using the up/down/left/right arrows that are just below the display. 


The MIT420 is capable of insulation resistance testing, voltage measurement, continuity/resistance, and capacitance testing.  None of the other units that I have are as capable as this one device.  I almost want to take my yellow multimeter meter out of my bag and just take this with me all the time now.  I've too often thought about grabbing an insulation tester after I'm already in the field.  This tester has everything I want in a neat little package.


Retrieving saved results

A megger isn't worth anything if you don't save your results for later comparison.  Saved tests are stored sequentially.image


The type of test is displayed, in this case a DAR:image


Using the up/down buttons you can see the T1 value, T1 voltage, T2 value, and T2 voltage.  Test times are adjustable in the setup menu.imageimage





One real world test with pics

Because all of the motors I tested at work had results that were 'too good' I had to find something that didn't peg out >100Gohm.  I had a failure of my A/C compressor wiring.  I didn't have the Megger when this picture was taken.  I hastily cut out the bad section of wire and spliced everything back together to get through the heat of summer.



Time to replace the damaged wiring.  The new wiring was quite a bit longer than the original and was heavier gauge wire.  You can see the black tape around the splice on the original wiring


This is a test of the compressor and wiring after replacement of the motor cables.  I realize now I should have pulled the screen protector to get a clearer image.  This is 34 seconds into a DAR at 250V.  Ended up with a DAR of 1.6 which is quite good.




Final Thoughts

I was able to use this Megger during a maintenance outage at my job.  I had tested multiple motors during the outage and it was really great to have a Megger that was this small and portable. Motor failures are inevitably going to occur and this is the right tool to have when you need to test for it.

  • I admit those two categories required some poetic license.  There isn't anything to design but no way to mark it as non-applicable.  The software really just consisted of an included CD with manuals and the e-book "A Stitch in Time".  There is no additional software and the CD works exactly as you expect. 


    The rest of my scores are compared to the older analog testers and 'whoop' testers that many of us have used.  I've had a few more recent test devices including a 5KV Fluke insulation tester.  I'm not trying to write a review for that device but I can contrast the portability of this device to that monstrosity.  This tester is a great mix of features, portability, and ease of use.  It's significantly less expensive than the 5KV capable test device that I already use, so for someone who doesn't need that range of voltages, this Megger hits all the right notes.  I work in 'heavy industry', so my use cases are a bit different than a hobbyist though. 

  • With this Megger you can do both of those things and then also perform your insulation resistance test on one device.

    Yes, they are much more useful than the old wind the handle and that's all it did style.



    Cheers for the clarification


  • I've updated the review.  I hadn't intended for it to be posted when it was as I considered it to be still draft. 

  • I didn't properly convey what I meant.  For my older equipment I'd first have to get a voltmeter out to perform a dead voltage test.  Then I'd have to flip to resistance to measure phase to phase for my motors.  With this Megger you can do both of those things and then also perform your insulation resistance test on one device.  Then add the capability of capacitance tester on top of that and it covers 99% of what I need in an every day meter. 

  • I had not intended for this to go live when it did.  I had written this as a draft and received a site error and was locked out of my profile for a few days.  I didn't realize it was actually posted until today.  I've added some more real world testing and I was expecting some real world failures at work.  While I did actually have some real world failures and they were found while using this Megger, they weren't failures that would show up well in pictures.  I did add some pictures for my Air Conditioner wiring, so there's that.


    As far as my scores, I can only rate it versus what I've used and this Megger really is that good.  Much of my career I was using 'whoop' style resistance testers.  I've had a couple of much older Megger brand testers with analog meter movement.  My most recent purchase is a Fluke 5KV tester that performs well for what it is, but it's really too big to carry around for most real world testing.  This Megger just hits all the right notes for ease of use and features.  None of my other previous devices can also function as a voltmeter, ohmmeter, and capacitance test device.  It's just....great!

  • Unfortunately for this road test there weren't any interesting things to show you from work as everything tested too good.  I even had a motor on an air compressor test at >100Gohm that was replaced 'just in case'.  We had some serious air end problems that were causing motor overloads.  I think we'd have been fine re-using the motor but we had a rebuilt motor on standby so....we replaced it anyways!  I also had a motor that blew a phase inside of its connection enclosure.  A wirenut blew apart and managed not to short itself to ground.  It only showed up as an open phase....

  • I hadn't intended for this review to be posted when it was.  I had an error through the interface while I was drafting this and it ended up being posted well before i was done and my account was locked out.  I intended to post more test results as I am able to perform some more.  I revised some of the review and I have added pictures of replacing the A/C compressor wiring.  That wasn't as fun as it looks.

  • They sure do.

    Keysight U1461A Insulation Resistance Tester - Review


    The setting can go lower than 100v which is great for comms cables.


    I don't believe that the Megger MIT420/2 is aimed at competing against these units.

    Maybe but they are all in the same market, so there will be some customers comparing what they get for their $.



    Megger have a very long history of making insulation testers, so they are well placed to be first choice.



  • Hello Kas,


    I find the scoring system a bit questionable for this tester and am not surprised it has a perfect score.


    The 'Specifications were sufficient to design with' and 'Demo software was of good quality' categories are not really applicable to this Road test, so how do you rate them? I guess you could apply some poetic licence to the specifications category.


    The remaining categories are likely to have high scores. The insulation tester is a relatively simple device, I have only ever come across one insulation tester that could not function on some circuits. The tester is extremely easy to use, I haven't had to use the manual for any operation guidance, only for settings adjustment. The support materials offered by Megger are, in my opinion, second to none.


    There may be an argument over the price to performance ratio, but this is a high quality tester from a premium brand and I would expect to pay more for that.


    Just my take on things,


    Kind regards,



  • Hello Mark,


    Keysight offer the U1461A and Fluke offer the 1587 'insulation multimeters' that have 100 to 1000V insulation test capabilities combined with some multimeter functions.


    For me personally, I don't believe that the Megger MIT420/2 is aimed at competing against these units. The Megger unit is predominantly an insulation tester with high safety specifications.


    Kind regards,