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Author Topic: Megohmmeter  (Read 6007 times)

Tom Bourke

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Megohmmeter
« on: October 15, 2014, 02:08:30 am »

So what would be an acceptable low cost Meg-ohmmeter?  At this point it is more of a curiosity for me.  I have a nice Fluke clamp on for the stuff that counts.  I have never used a megger and would like to learn.
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I have a mild form of Dyslexia that affects my ability to spell.  I do use spell checking to help but it does not always work.  My form of Dyslexia does not affect my reading.  Dyslexics of the world untie! <a href="http://www.cwalv.com" target="_blank">http://www.cwalv.com</a>

Scott Holtzman

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Re: Megohmmeter
« Reply #1 on: October 15, 2014, 03:47:10 am »

So what would be an acceptable low cost Meg-ohmmeter?  At this point it is more of a curiosity for me.  I have a nice Fluke clamp on for the stuff that counts.  I have never used a megger and would like to learn.

Out of curiosity what is "stuff that doesn't count"?

Anyway, a nice crank amprobe meger on eBay can be had for $100 or so.  The generate a nice bit of voltage with the crank gen and I like the 0 latency of the analog meter.

Without spending $1000 your are not going to get more accuracy.

These are designed to test insulation breakdown.

I may have been confusing the issue in several posts.  When I say "Megger" I am not speaking of a megohmeter but a Megger Instruments ground tester.  These are used to test the quality of ground fields and read accurately below 1 Ohm




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Mike Sokol

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Re: Megohmmeter
« Reply #2 on: October 15, 2014, 09:45:01 am »

Anyway, a nice crank amprobe meger on eBay can be had for $100 or so.  The generate a nice bit of voltage with the crank gen and I like the 0 latency of the analog meter.

Without spending $1000 your are not going to get more accuracy.

I've only used the crank ones a long time ago. But I see that Amprobe make a battery operated digital one you can buy for $250 on Amazon. http://www.amazon.com/Amprobe-AMB-25-Digital-Insulation-Resistance/dp/B0046HY8NS

I'll ask my RVIA guys what they use for testing new Recreational Vehicles since that's part of their build spec.
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Steve M Smith

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Re: Megohmmeter
« Reply #3 on: October 15, 2014, 10:01:17 am »

I used to use a hand cranked one in the late 1980s for testing the insulation between power transistors and heatsinks on high power switch mode power supplies.


Steve.
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Stephen Swaffer

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Re: Megohmmeter
« Reply #4 on: October 15, 2014, 10:13:23 am »

I use a Fluke battery operated-iirc about $350 and it has served me well-motor tests and such. Mine will test at both 500 VDC and 1000 VDC.

Keep in mind you do not want to "meg" solid state loads-inverters, etc-make sure they are disconnected before you test ( for that matter an inverter genny is not a "load", but you don't want that connected either.)

IMO, for most sound/lighting setups a simple ohm meter would be a sufficient test to make sure there are no dead shorts to ground.  I usually only pull mine out for motor tests or if I am dealing with a "high energy"circuit-not a defined term but just where I am comfortable.  A short on a 20 amp 120 V circuit usually doesn't create too much excitement-a 400 amp 480 volt 3 phase in another story-and those will get megged every time!   But it never hurts to be on the safe side.
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Tom Bourke

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Re: Megohmmeter
« Reply #5 on: October 15, 2014, 10:40:43 am »

Out of curiosity what is "stuff that doesn't count"?
Poor choice of words, sorry I was tired.  I grab my $250 Fluke when doing work with show power and high current/voltage work or when it is handy.  My second meter that goes with me on all jobs and for more general electronics work is my $40 Tenma.  It has a lower cat rating and no clamp but has features handy for low voltage electronics work.  When the Fluke is not handy I will use it on the test points of a distro or trouble shooting stuff down stream of the distro.  All my other meters have been relegated to 12V and under or the garbage.

I have no use for a ground rod tester however an insulation tester sounds very interesting for some of what I do.  However I don't want to spend hundreds on one till I know for sure it will be used a lot.  A lower cost "trainer" that can later be relegated to the gig bag would be cool.
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I have a mild form of Dyslexia that affects my ability to spell.  I do use spell checking to help but it does not always work.  My form of Dyslexia does not affect my reading.  Dyslexics of the world untie! <a href="http://www.cwalv.com" target="_blank">http://www.cwalv.com</a>

Mike Sokol

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Re: Megohmmeter
« Reply #6 on: October 15, 2014, 11:21:40 am »

A lower cost "trainer" that can later be relegated to the gig bag would be cool.

Supro makes one for $89 but I don't know if it's junk or not... http://www.zoro.com/i/G0712695/?utm_source=google_shopping&utm_medium=cpc&utm_campaign=Google_Shopping_Feed&gclid=CNqI59r6rsECFW4F7AodWm4ApQ
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Lyle Williams

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Re: Megohmmeter
« Reply #7 on: October 15, 2014, 04:47:38 pm »

The Victor VC-60B+ found commonly on ebay works fine.
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Tom Bourke

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Re: Megohmmeter
« Reply #8 on: October 16, 2014, 03:57:26 am »

The Victor VC-60B+ found commonly on ebay works fine.
I found the Victor and also found a Vichy with the same model number but has a couple of extra features.  Most notably normal resistance in addition to the megger function and VAC measurement.  http://www.amazon.com/NEEWER%C2%AE-Digital-Insulation-Resistance-MegOhmmeter/dp/B00DVFNBPC/ref=pd_sim_sbs_hi_1?ie=UTF8&refRID=02X6J1B6R7RRGND0H3G7#product-description-iframe  Tempting.
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I have a mild form of Dyslexia that affects my ability to spell.  I do use spell checking to help but it does not always work.  My form of Dyslexia does not affect my reading.  Dyslexics of the world untie! <a href="http://www.cwalv.com" target="_blank">http://www.cwalv.com</a>

Tom Bourke

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Re: Megohmmeter
« Reply #9 on: November 05, 2014, 01:12:14 pm »

I bought the Vici VC60B+ I linked to above.  The meg-ohm settings seam ok for accuracy.  I had a pile of 1 to 10 meg resisters here and the meter matches the markings in the 250 and 500V range.  1000V rage was a little higher but that could because I was at the extreme low end of the range for that setting.  The AC voltage readings are high (130/266V when the Fluke says 127/255V) on my house voltage.

Over all I am happy.  It is good enough for my hobby stuff. At a 10th the cost I can live with lower accuracy.
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I have a mild form of Dyslexia that affects my ability to spell.  I do use spell checking to help but it does not always work.  My form of Dyslexia does not affect my reading.  Dyslexics of the world untie! <a href="http://www.cwalv.com" target="_blank">http://www.cwalv.com</a>

ProSoundWeb Community

Re: Megohmmeter
« Reply #9 on: November 05, 2014, 01:12:14 pm »


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