Handheld meter robustness testing

[Fungus]

Which is safer, a self-certified 200€ Japanese CAT IV 600V DMM that is the subject of two YouTube videos

Joe's video clearly says "Part 1 of 3" in the title, so that's at least four videos.

[joeqsmith]

Which is safer, a self-certified 200€ Japanese CAT IV 600V DMM that is the subject of two YouTube videos

Joe's video clearly says "Part 1 of 3" in the title, so that's at least four videos.

I tend to be long winded and do a little more than open the box and give them five stars. 

[bdunham7]

A good question would be: is there any verified information how many industrial accidents were caused by using UNI-T meters..?
A research, by numbers, how much more accidents happen by using UNI-T than Fluke?
I would like to see that information..

The problems with that is are 1) there probably aren't very many of these accidents, not like auto accidents anyway  2) arc-flash and other accidents are probably more likely to be caused by issues other than a failure of the meter, like dropping or mishandling, mishandling the probes or working on circuits beyond the low voltage range, and 3) if you just looked at what type of meter was being used during such an incident it is much more likely to be Fluke because nobody (at least that I know, here in the US) is going to be out working on sawmill motor during a thunderstorm with any meter by UNI-T.

[AndrewBCN]

Which is safer, a self-certified 200€ Japanese CAT IV 600V DMM that is the subject of two YouTube videos

Joe's video clearly says "Part 1 of 3" in the title, so that's at least four videos.

Awesome! 

[bdunham7]

People here should realize that most consumers do not take apart their DMMs, etc when they get them to check the internals, they just use them as is. And almost all of us are totally incapable of judging the safety or robustness or standards compliance of a DMM, even when we have it taken apart in front of our eyes.

Well apparently if you buy UNI-T you better take it apart to make sure they haven't omitted parts in production that were needed to get their 'certification'.  And no, we aren't "totally incapable" of observing that one product uses carefully matched isolation slots and internal shielding, has larger PTCs, uses higher interrupt rated fuses, observes published creepage and clearance requirements, etc etc--and another product doesn't do all that.  Of course it is true that we generally don't have any concrete means of correlating those features to actual performance on a particular test, but as a relative comparison tool I don't see the problem.  I don't buy the notion that consumers should make their choices solely or even primarily on the results if this sort of testing or 'level' of certification--even if the results aren't fake. 

Imo independent testing and certification is a valuable step in bringing a DMM or any piece of test equipment to market, and every DMM review should clearly state whether the device reviewed has been independently tested and certified or not, to what standards, and by which independent certification company. Whether this will actually encourage manufacturers to get their products certified is another question, but it would be a step, however small, in the right direction.

The blanket statement that independent certification is "worthless" is, imo, a step in the wrong direction. Also, any certificate can be "fudged", that applies to just about anything, from DMMs to diesel engines to jets. The question is whether it is worth it to "fudge" the certificate and risk being exposed. Personally I'll never buy another VW car or fly in a 737-MAX, but that's just me and it seems I am a rather rare case.

You seem to be defeating your own argument.  Those examples you gave were exactly what happens when a company concentrates on meeting getting past the test for this or that standard instead of devoting their efforts to building a good product. 

[floobydust]

Feel free to point out any safety issues:

joeqsmith says his content and this thread is not about safety, it's about robustness.

The follow-through current is zero. It's mains transient testing minus the mains. So a GDT looks wonderful, when it's actually not.
Kreosan had some fun with their transient testing which included mains, might be worth figuring out.
edit: spelling

[AndrewBCN]

...
Well apparently if you buy UNI-T you better take it apart to make sure they haven't omitted parts in production that were needed to get their 'certification'.  And no, we aren't "totally incapable" of observing that one product uses carefully matched isolation slots and internal shielding, has larger PTCs, uses higher interrupt rated fuses, observes published creepage and clearance requirements, etc etc--and another product doesn't do all that.  Of course it is true that we generally don't have any concrete means of correlating those features to actual performance on a particular test, but as a relative comparison tool I don't see the problem.  I don't buy the notion that consumers should make their choices solely or even primarily on the results if this sort of testing or 'level' of certification--even if the results aren't fake.

Well that is your opinion which you are naturally entitled to, and it seems it is based on how you compare your own expertise vs that of entire teams of electronics engineers that do testing day in, day out with special-purpose equipment in dedicated labs. Which brings us back to the article that Joe linked to.

Good for you, you and others here are all experts. And probably because I am such an idiot, I prefer to rely on independent certification processes.

[Fungus]

Kreosan had some fun with their transient testing which included mains, might be worth figuring out.

I'm not old enough to watch that. Apparently.

(How old would I have to be? Methuselah age?)

[Fungus]

And no, we aren't "totally incapable" of observing that one product uses carefully matched isolation slots and internal shielding, has larger PTCs, uses higher interrupt rated fuses, observes published creepage and clearance requirements, etc etc--and another product doesn't do all that.

Well that is your opinion which you are naturally entitled to, and it seems it is based on how you compare your own expertise vs that of entire teams of electronics engineers that do testing day in, day out with special-purpose equipment in dedicated labs.

You don't have to be an expert to see that stuff is in there.

I don't imagine Hioki puts Those components in there randomly, hoping for the best.

PS: Don't forget the guard traces: I can see those, too. I don't think even Fluke does those.

[bdunham7]

jeoeqsmith says his content and this thread is not about safety, it's about robustness.

The follow-through current is zero. It's mains transient testing minus the mains. So a GDT looks wonderful, when it's actually not.
Kreosan had some fun with their transient testing which included mains, might be worth figuring out.

If we're saying that it isn't about 'safety' as in industrial arc-flash accidents, then I'd agree, these evaluations aren't conclusive.  But IMO, 'safety' and 'robustness' can't be separated that easily.  As your video shows, you don't need a high-fault current CATIII/IV environment to blow something up and potentially be injured, although you likely won't be vaporized.  And I consider it paramount that the meter continue to work, whether that is considered a safety issue or not.  IOW, I don't think that a meter that is not 'robust' can be considered 'safe'. 

As for MOV vs GDT, obviously the issue with a GDT (other than speed) is that it clamps to a low voltage once activated, which means something else has to absorb the energy and the voltage need to cease momentarily for conduction to stop.  The MOV will stop conducting when the voltage goes below the knee.  I don't know anything about that GDT design in the Hioki, but I have to wonder what happens if you are measuring 1000VDC in a HVDC solar system (a CAT III  environment apparently) and you get a transient large enough to arc the GDT.  I hope that either the PTC is up to the task or those input resistors are fairly high values so that the current at 1000VDC--once the transient ends--is low enough that the GDT stops conducting.

[joeqsmith]

jeoeqsmith says his content and this thread is not about safety, it's about robustness.

The follow-through current is zero. It's mains transient testing minus the mains. So a GDT looks wonderful, when it's actually not.
Kreosan had some fun with their transient testing which included mains, might be worth figuring out.

Your first sentence is true but the bolded statement is not accurate.  I use the open circuit voltage waveform but with 2X the FWHH.   The short circuited current is limited to about 20J max.  Even with no AC lines, the transients I apply are no where near the energy of what the actual IEC surge standards call for.  Again, that was never a goal.  While I can continue to correct these statements for another four years, there are going to be those who never understand it.   Their expert opinions will continue to fuel the confusion.  Those average Americans anyway... Oh wait... 

[Fungus]

jeoeqsmith says his content and this thread is not about safety, it's about robustness.

True, but joe's little sparks indicate the presence of ignition sources in arc flash situations.

Joe doesn't evaluate what would happen next if there was a ton of energy available behind that spark but any meter that sparks internally at a given test voltage should be on the "probably unsafe" list.

PS: Even Joe's little sparks can make meters jump around inside the testing box and that alone could be enough to make you fall off a ladder in fright if the meter was in your hand.

[bdunham7]

how you compare your own expertise vs that of entire teams of electronics engineers that do testing day in, day out with special-purpose equipment in dedicated labs.

No, you just don't get it.  I don't compare or equate my expertise or observations with "entire teams of electronics engineers that do testing day in, day out with special-purpose equipment in dedicated labs", in fact I like working on and repairing equipment designed by such people because I can admire and learn from their efforts.  However, I don't confuse high-quality products made by such companies with rubbish hacked together on a shoestring by third rate hacks.  There are many impediments to producing a high-quality product, and when there is intense pressure to meet cost control and time objectives, quality standards become minimal requirements that just have to barely be met--if that.  My distrust of these low-buck purveyors of proven unreliability is not based on technical expertise, but rather first-hand experience of how corporations and their management function. 

I am such an idiot, I prefer to rely on independent certification processes.

You just cited examples of companies you would avoid because of egregious failures of their independently (to a point) certified products.  I just had a UL certified product cause a fire due to piss-poor construction of a connector.  If you accept a single certification test of a product from company at the bottom of the market (with a history of failures in the jqs test and questionable ethics regarding omitting parts) as positive proof that it will provide sufficient protection to the user in an extremely harsh, dangerous environment, well that is idiotic.

[AndrewBCN]

how you compare your own expertise vs that of entire teams of electronics engineers that do testing day in, day out with special-purpose equipment in dedicated labs.

...
I don't compare or equate my expertise or observations with "entire teams of electronics engineers that do testing day in, day out with special-purpose equipment in dedicated labs", in fact I like working on and repairing equipment designed by such people because I can admire and learn from their efforts.
...

You misunderstood. The teams I was referring to are the testing teams at certification companies, who you seem to believe don't exist or don't matter. As to comparing yourself to the teams that develop testing equipment at any of the major manufacturers, well... I'll leave you to your delusions of grandeur. 

[joeqsmith]

...
If we're saying that it isn't about 'safety' as in industrial arc-flash accidents, then I'd agree, these evaluations aren't conclusive. 
...

Again, I want to be very clear that the IEC surge has nothing to do with arc-flash.  And while I based my open circuit voltage waveform on the IEC surge open circuit waveform, that's about all they have in common.  Comparing anything I show to a surge test shows a total lack of understanding.   Thinking it has anything to do with arc flash testing is a whole new level.     

Over the years I have heard of three arc flash events from people I know.   Two of them resulted in death where a procedure was not followed.  It had nothing to do with the equipment.   The investigation in the third case revealed a faulty meter (nothing like what I am reviewing).  In that case no one was injured thanks to PPE. 

[bdunham7]

You misunderstood. The teams I was referring to are the testing teams at certification companies, who you seem to believe don't exist or don't matter.

OK.  Do you mean 'teams' like the team at the UL that certified the piece of junk that nearly burned my house down or the team at the FAA that certified the Boeing 737 MAX?  Are you really going to have blind faith in some 'team' that you know nothing about in a 'laboratory' that you know nothing about?  Do you have any actual knowledge about the lab or the process other than spelling the name of the city they are in?  This reminds me a lot of the discussions elsewhere about calibration laboratories. 

As to comparing yourself to the teams that develop testing equipment at any of the major manufacturers, well... I'll leave you to your delusions of grandeur. 

Either you misread what I actually said or you actually think UNI-T is a 'major manufacturer', a term which to me implies an A-brand, not a mass marketer of copycat cut-rate rubbish.  You seem intent on ridiculing my statements even if you have to misquote or misconstrue them to do so.  Are you still sore about the "fanboy apologist fantasy" wisecrack? 

[floobydust]

jeoeqsmith says his content and this thread is not about safety, it's about robustness.

The follow-through current is zero. It's mains transient testing minus the mains. So a GDT looks wonderful, when it's actually not.
Kreosan had some fun with their transient testing which included mains, might be worth figuring out.

Your first sentence is true but the bolded statement is not accurate.  I use the open circuit voltage waveform but with 2X the FWHH.   The short circuited current is limited to about 20J max.  Even with no AC lines, the transients I apply are no where near the energy of what the actual IEC surge standards call for.  Again, that was never a goal.  While I can continue to correct these statements for another four years, there are going to be those who never understand it.   Their expert opinions will continue to fuel the confusion.  Those average Americans anyway... Oh wait... 

Is your goal theoretical robustness or real-world, or theatrical robustness lol. I think even us non-Americans can appreciate the differences.

Mains transients are superimposed on the sine-wave, so any crowbar (i.e. GDT) action will last for a long time, not mere usec but msec. Typically 1/2 cycle to zero-cross but much worse when there is copper vapor and soot to clear. Cat. III can have high fault currents for the long duration which is the safety issue I am trying to point out, but you seem to be missing.

[bdunham7]

Again, I want to be very clear that the IEC surge has nothing to do with arc-flash.  And while I based my open circuit voltage waveform on the IEC surge open circuit waveform, that's about all they have in common.  Comparing anything I show to a surge test shows a total lack of understanding.   Thinking it has anything to do with arc flash testing is a whole new level.

I'm not sure 'nothing to do with' is a fair assessment.  One possible path to a catastrophic arc flash incident starts with a meter breaking down under something resembling the IEC surge test.  You don't need to have an arc flash to have an injury incident or a fire, but in the wrong time and place, an arc flash is one possible result.  As both you and I have said now within the past few posts, there are a lot of other ways to start an arc flash as well. 

[joeqsmith]

Is your goal theoretical robustness or real-world, or theatrical robustness lol. I think even us non-Americans can appreciate the differences.

Mains transients are superimposed on the sine-wave, so any crowbar (i.e. GDT) action will last for a long time, not mere usec but msec. Typically 1/2 cycle to zero-cross but much worse when there is copper vapor and soot to clear. Cat. III can have high fault currents for the long duration which is the safety issue I am trying to point out, but you seem to be missing.

My goal was to run various meters against a common standard to determine which were more electrically robust.  Obviously the IEC standards are superimposed on the line.  Again that has nothing to do with what I have been showing for the last several years beyond basing my open circuit voltage waveform on the surge.   I have had a few people ask me about testing AC line devices which point to just how ignorant some viewers are.  I don't see that changing although I run into it less and less.       

Again, I want to be very clear that the IEC surge has nothing to do with arc-flash.  And while I based my open circuit voltage waveform on the IEC surge open circuit waveform, that's about all they have in common.  Comparing anything I show to a surge test shows a total lack of understanding.   Thinking it has anything to do with arc flash testing is a whole new level.

I'm not sure 'nothing to do with' is a fair assessment. 
...

Is that your expert opinion based on your interpretation of what several others have posted about their own interpretations of the standards,  which I doubt they ever actually read?    It seems par for the internet. 

[EEVblog]

HIOKI also "reached out" to me a while ago.   I use some of their equipment for industrial work.  I don't believe they are certified. 

That's common for the Japanese meters, they do self certification to the standard.
But as opposed to the Chinse companies, the Japanese actually do do it and take it seriously.

And to be clear, you're suggesting that ALL of the Chinese do not? 

Of course not.
Uni-T offer some models that are independently tested, but they also offer many other models that are crap.
The vast majority of chinese meters are not certified, you know that.

As long as we are making broad statements, I'm curious to know your opinion which is safer, a Chinese product certified by Intertek or a self certified Japanese product?

I'm not playing your game, sorry.

[EEVblog]

HIOKI also "reached out" to me a while ago.   I use some of their equipment for industrial work.  I don't believe they are certified. 

That's common for the Japanese meters, they do self certification to the standard.

[/quote]

I stand corrected.
I forgot that Sanwa do independent testing by SGS.
Not sure if that's for all meters, but if they go to the trouble for their pocket meter then I'd assume they do it for the bigger meters too.

[joeqsmith]

As long as we are making broad statements, I'm curious to know your opinion which is safer, a Chinese product certified by Intertek or a self certified Japanese product?

I'm not playing your game, sorry.

There's no way I would touch that one but I thought you may take a swing at it. 

***
As long as I am thinking about it, a member had asked about connecting the UT61E+ to the 220V mains with it set to the resistance mode.   I had checked your review and you did not run that test.  Because I had already damaged the one I bought, any way to talk you into running it with yours?   

[joeqsmith]

Part 3, the damaged/repaired/slightly modified UNI-T UT61E+ meets the gas grill starter and other implements of destruction.   

[Fungus]

No, you just don't get it.  I don't compare or equate my expertise or observations with "entire teams of electronics engineers that do testing day in, day out with special-purpose equipment in dedicated labs", in fact I like working on and repairing equipment designed by such people because I can admire and learn from their efforts. However, I don't confuse high-quality products made by such companies with rubbish hacked together on a shoestring by third rate hacks.

Do you learn nothing from people who are asked to make a full size multimeter at a $25 price point?

If anything, it's more difficult then working on a massive budget to make a "high quality" meter.

As long as we are making broad statements, I'm curious to know your opinion which is safer, a Chinese product certified by Intertek or a self certified Japanese product?

I'm not playing your game, sorry.

There's no way I would touch that one but I thought you may take a swing at it. 

Yep. Anbody that frames this as "China vs. Japan" instead of "Uni-T vs. Hioki" is at the Donald Trump level of debate.

[EEVblog]

As long as I am thinking about it, a member had asked about connecting the UT61E+ to the 220V mains with it set to the resistance mode.   I had checked your review and you did not run that test.  Because I had already damaged the one I bought, any way to talk you into running it with yours?

Left on for 10 seconds, survives just fine at the nominal 245V here. Readings a smidge low as the PTC recovers.