In this video, we test a high quality Fluke Megohmmeter against two cheap Chinese versions from Amazon and see how they perform.
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Read all the tech tips, take the quizzes
and find our handy calculators at https://www.hvacrschool.com/
Ryan with hvac school here and got a couple of different, very, very inexpensive, mega meters or mega meter manometer, whatever ever you want to pronounce it get a couple difference very inexpensive ones from Amazon and I'm comparing it to my rather expensive fluke. 1577. That's what it says there 1577 fin fluke and we're gon na see how they compare now before we get into it. I just want to say that I'm not assessing the durability of the products or even the safety of the products, because how on earth could I do that without using them in the field for a long time, I'm just looking at the functionality? Alright, so here's what I've got.
I've got a victor v60. I've got a victor V, 60 B that I got off of Amazon. It's got a nice big display. I think it runs about 40 bucks.
I've got my fluke 1577, and I've got this thing that I can't even read most of the words on it. Toran you, whatever one thing, you'll notice is this one here I can't even read the category of the meter. It's probably some of this Chinese on the fluke. It's a category three or a category four, depending on how it's being used, and the victor is a category three meter which just dictates that both of these can be used for regular HVAC use this one.
Here I don't know, I'd be afraid if it got hit with some transients that it might explode in your hand, I'm not assessing you know how safe these are to use. Obviously, I feel very comfortable with the fluke, but let's see how they do. What I've got is I've got a couple resistors here and make sure that these holding any charge. That's one thing to be careful with so this one here is a 200 mega ohm resistor.
It's also rated for really high voltage, so we're safe to use this all the ranges and this one here this is a smaller one. This is a 20 mega ohm resistor see here. So this is a 1 watt resistor from a voltage standpoint, I'm only going to take it up to 500 volts max, which is generally what you would use to test a mega meter all right so before we actually test these out. I want to just cover what a mega meters for it's for testing winding breakdown over time, so you can take a sample and then you can take another sample later say year later and you can see if you have winding breakdown, you can use it to check Insulation breakdown on wires, which is why, actually, if you look on the fluke, it says insulation on it, because it's an insulation test, he uses a high voltage anywhere from 250 volts.
As you can see here on the victor 500 volts would be the typical that we would use for 2o, a 240 volt appliance. That would be the the right voltage to use to say test a typical compressor and then, if you had a higher voltage, you know 480 volt, then you would use the thousand volts, but this one's actually nice because it has the 250. So if you wanted to test 120 volt appliance, you could use the max 250, which is just a safer, safer voltage. You don't want to use more voltage than you need in order to test the insulation for technicians, a/c technicians out in the field. It's going to be practical because sometimes just using the little mega ohm meter built into your typical digital multimeter, isn't going to work effectively to tell if you do have a short to ground. I mean we've all been in the position where you are applying line voltage to a compressor and it's dripping the breaker. But when you test it with your meter, you're not measuring your booster measuring infinite. Ohms are very, very high ohms, and so sometimes that befuddled tax, the key thing here is you don't want to use this to compare one compressor, that's different than another compressor.
So, for example, with a scroll compressor, you're gon na read lower or mega ohms, and you are on a reset, so you don't want to go to a reset or even different brands can vary. So you don't want to go to one compressor and say well that one read 100 mega ohms and it was okay. So now, if I go to another one, it reads two mega ohms. That means it's failed now, I'm to is definitely kind of the bottom limit that that's usually kind of a safe number to use.
When you, once you go below two megaohms, then you are pretty much shorted, but you'll get a feel for it with the different types of compressors that are out there as you use it. The other thing to be careful with, is you don't let some people have talked about using it on thermostat wires things like that, obviously, if you're applying two hundred fifty five hundred or thousand volts to something, it's got to be rated for that voltage and most of Your control wires aren't gon na be rated for that, so I'm generally not gon na suggest using a mega ohm meter for anything that you aren't clear on what the maximum voltage rating is and also you'd never want to use a lot of electronics. You never want to use them on an energized circuit, so those are all some safety things. You definitely want to check and make sure that it is not an energized circuit before you start to use these so anyway, here we go we're gon na test each one and see what we get okay, so first we're gon na start with the fluke we're going To take the nice leads, the fluke obviously has really nice alligator clips or a crocodile clips, as some people will call them.
We want to make sure that we get it in there so that it has good connection. If I put it too far back in the jaws, it's not connected to this small wire on this resistor. So remember this is the 200 mega ohm resistor, so we're gon na go ahead and put this in the insulation test mode and then hold down the button. 500, volts 214 mega ohms at 525, volts DC, alright, so that's kind of our baseline.
We have the rating on the resistor that tells us 200 mega, ohms and Fluke is essentially telling us 200 mega ohms a little little higher than the HEPA we can. We can be fairly confident that that is correct, so I'm going to shut it off first and then, before I touch anything, I'm just gon na discharge these together to make sure that they don't have any charge left in it. Next, we're gon na go to the 20 mega ohm make sure we get it in the jaws where it's connecting real. Well there it's good, I'm gon na go ahead and put it on, be careful, never to touch these when you're doing this, because it will give you a nasty little shock installation test, 19.7 mega ohms. Alright, so we've established that the manufacturers say this is 200 and this is 20 and the fluke is measuring right in that range. So, let's shut it off. I just do that with the clamps, because the high mega ohm resister well, it is a path. It's a very high impedance path means it's a very high resistance path and so just connecting them together, distance Church, that's just not any charge store to the capacitors before I go touching anything all right.
So I've got that connected to my to 100 mega ohm resistor. We're gon na go ahead and make sure that's on 500 press the power button now press the test see this takes a little bit to get to the get to the range, but 214. 202. 14.
This reads: 216. Now you watch out this slowly drops like that. I would not want to touch it until it's reading zero and then, even once it is I'm going to touch these together, just to make sure that there's nothing left now we're gon na go ahead and go to the 20 mega ohm resistor and again. This is simulating a winding and a compressor or a wire.
You know why our breakdown in a a wire insulation breakdown in the wire - I should say all right here: we go 500 volts, so this is reading 28 mega ohm. So it's a little on the high side. You know the fluke was reading under 20. This is reading 28.
So it's not perfect in comparison to the fluke, but it's still serviceable. Let's change the voltage down to 250 and see if that changes anything wait for it to settle down there. We go so when we're reading at 250 volts it's reading a little bit more accurately, which is interesting. I don't know the exact reason for that, but you can see that that doesn't make a difference.
Alright, so the notes not quite as accurate but still serviceable in testing a compressor or something like that, all right. So now, let's show their power off. Okay, now we're gon na move on to the super super cheap one that I bought on Amazon, the zucchini Amann really read other than a couple words on it. You can read insulation test, that's something these leads actually came with it, the whole league kit and that the alligator clips and everything came with it.
Now, if you look inside these alligator clips, the connections aren't that great. So I wouldn't really trust that, but but again we're just seeing how it works functionality alright, so we are connected set this to the side where it's not going to touch anything. Now we are going to hit anything physical. That has a light button too. So that's Man, Z. Now we're going to go and hit the button. Alright, you can see it's reading right. At 200 I mean dead-on 200 mega ohms.
Alright, this one also only has a fixed voltage. So this just has a 500 volt, 500 volt fixed voltage. That's it doesn't do anything other than 500 volts. Alright.
So now we're gon na just connect that tap these together make sure we're not holding a charge connect our 20. There you go there. We go 20 mega ohms. So, that's that a lot of guys will dispute the value of having a mega ohm meter on the truck, and I don't dispute the value of it.
I dispute how often you need to pull it off the truck, which means that do you really want to spend a lot of money for a really expensive mega ohm meter? That's for you to decide, but these actually give you a reading. There are some common mega meters and it won't name any brands right now that just say good or bad, that are made very simplistically for the HVAC market and I think it does what it says it does, but it doesn't give you an actual reading what I Would prefer to have? I may go a meter that gives me a reading. There's a lot of things. You've got to be careful with on these, so I'm not gon na put them in the hands of a newbie tech who doesn't know what they're doing you can shock yourself to put an energized equipment.
You could damage the device you could potentially have an arc flash if you connected it to very high voltages, there's a lot of things to think about there, but what we've established is that, from a functionality standpoint, the least expensive, the most expensive function very similarly, i'm Brian with hvac school thanks for watching.
Awesome as always
Correct title would be “Expensive Chinese Meter vs Cheap Chinese Meter”
Pull mine "off the truck" multiple times a day…..
Love my HIOKI and Flukes…..but also have a few 20/50 buck thingies….For work I mostly use the Megger MIT1525 but cannot compare with any of these,(only pricewise it is insane….> 6K $)
Power = Voltage squared / Resistance, I believe you had plenty of room with power on them resistors, looks like the 20 meg resistor will handle 4.472 Kv. , that’s if you can believe it’s a 1 watt resistor, it looks like an 1/8 watter to me which would mean about 559 V tops and that looks a little more reasonable to me, I don’t see that tiny little thing dissipating a full watt, i’ll bet the thing got warm ! Also I kinda liked that Chinese meter but it doesn’t look too durable. I’d go with the fluke, if I could afford the thing that is.
The vici is a good quality continuity/ insulation resistance tester . And is used to test electrical installations mainly domestic . The fluke is a fantastic meter the other meter is a kewtech made for the Australian and American market and again is a fantastic meter that and the vici are very capable meters. Oh and you should always carry out the insulation resistance test at five hundred volts on circuits of 50v to 500 v and any thing less than 50v you test at 250v and if there is any sensitive equipment in circuit you test at 250v or test line and neutral combine to earth
Great video thank you
I think the question which of them to use is depend By a professional.
If you are professional electrician you cannot use the Chinese isolation tester
I know it doesn’t matter just saying Service area Nepean??
Your leads are backwards on the fluke
thank you very much for the demo . very helpful .
Bom dia de portugal
great video btw…. TQ . im currently using megger/ megaohmmeter mostly to test ultrasonic piezoelectric . trying to review the item 1st before buying the cheap 1 Are you in Orleans ?
Can you redo the Tianyu non digital one again? you never turned the light on during the reading, i couldnt see it. redo the video with the light on
One rarely discussed benefit of Chinese-to-Amazon products like these is that western brands are often slow to adjust what they charge to the consumer as their manufacturing costs inevitably and continuously go down. I’m happy to pay extra for electronics when they are (very rarely) produced at living wages, especially by US workers, but you have to wonder how much the profit margins for Fluke, etc. have widened at our expense over the past 10-15 years when they are currently charging 1200%+ over their cheapest competitors. I don’t know anybody in the trades who takes home profits like that. Seems unreasonable to me.
Check out eevblog with electronics engineer Dave Jones. You will learn more about test meters than you want to know!
Wanted to see your video but the ads before the video are just too long.
I have the UNI-T UT505A Insulation tester. Good meter and only $200.
Its a 20% resistor, so a 200 meg resistor could be exactly that or 20% in either direction of that. You can't say which meter was correct unless you know you had a very specific value to begin with. Suggest you buy a 1% resistor or even .1% and keep it only for calibration checks if calibration is really that important to you.
Plss be direct.
megohmmeters are a great preventive maintenance tool to have on the truck. Primary purpose is not just testing for high resistance grounds, it is for evaluating the refrigerant and oil atmosphere that a hermetic compressor is exposed to. As moisture and contamination in a system increases, the megohmmeter reading will decrease. On large equipment, the major motors and compressors are megged as a part of annual maintenance. Base-lining the reading on start up, and tracking the reading over time, is a great way to evaluate the atmosphere that a hermetic motor is living in. Potential compressor failures can be detected, and the equipment taken off line before a major burn out, which would create a huge cleanup job.
Thanks for this great video ! What is and how do you the "ground" port on the tester?
I love the comparison the victor looks alright but you can’t beat the Fluke takes the guess work out of finding the proper values to test the resistance, Thanks for sharing the experience
I think that this B&K Precision 307A Analog Megohmmeter @ $167 stands in the middle ground of Fluke expense for a unitasker and rather inexpensive imports. Thanks for the video. Very informative.
Chinese makes super cheap quality device.
What’s your opinion on the supco m500 as far as hvac use? Thanks
good video,how well goes those tools work on automotive circuits ,12-14 volts, and other things on cars, i am a GM mechanic but am interestested in new technology
Good video. Also, don't ever meg a compressor while it's in a vacuum. Service area Kanata??
Crazy how accurate the cheapest was, and for some reason I love dials and needles vs just a digital readout. I gues the leads you did not use on the fluke is the remote test lead.That is a really handy thing to have that the fluke offers.
Fluke is money well spent.
That being said, interesting results.
Good video, however can you do a video with an actual single and 3 phase units. You can use a test lead where C,S & R are wired together (to the red side wire) and the other wire connects to ground. What this does is complete one test (rather than 3), however it does give you the lowest reading e.g if R to C was shorted, it will dtsplay that rather than the good S to C one (same for 3 phase) Service area Barrhaven??
Good video.
Have had the Victor unit for over a year, but only used it once. Are you in Ottawa ?
Great video Br”y”an. Thank you, and keep em coming.