Handheld meter robustness testing

[Fungus]

I would like to know how often in the real world a surge or some other anomaly comes along

It definitely happens.

If you're the sort of person who pokes bits of metal into mains sockets then why skimp?

It's not even a case of skimping: The safest meter in joe's testing is the Fluke 101 which costs $42, shipping included. If socket-poking or power supply repair is a daily thing then you'd have to be an idiot to use anything else.

For working with low voltage DC though isolated power supplies then it's not so critical. Anything that passes the static electricity test will be probably be good enough.

(just don't lend it to anybody or leave it where children might find it and poke it into a mains socket on a random setting...)

[exe]

I would like to know how often in the real world a surge or some other anomaly comes along

It definitely happens.

Please forgive my ignorance, could you please describe under what conditions this happens? And what happens?

I see a lot of discussion here that these cheap-ass multimeters are "low voltage only". Yet *none* of them failed to measure voltage in mains. I also didn't see meters failing below 1kV. So, where the danger comes from? (assuming probes are of any decent quality).

My next question would be how failing to survive a "high-energy test" compromises safety (if the meter does not completely explode, of course).

[SeanB]

Think of you having them in a power outlet, with an airconditioner plugged into the power strip. You are measuring the drop in mains voltage when the unit power on the compressor. While doing that, with the compressor running, your breaker trips, disconnecting the compressor. However, there is a very large transient from the still running motor, and this generates a 2kV or more pulse on the mains wiring leading to the unit. Your meter gets this pulse, with more than enough energy to damage it, and a non protected meter will have the input side blown. Then somebody turns the mains back on, and you, believing that the meter reading of zero volts, then goes to disconnect the mains wiring from the compressor, and connect yourself across the mains. RIP

[IanB]

Please forgive my ignorance, could you please describe under what conditions this happens? And what happens?

I see a lot of discussion here that these cheap-ass multimeters are "low voltage only". Yet *none* of them failed to measure voltage in mains. I also didn't see meters failing below 1kV. So, where the danger comes from? (assuming probes are of any decent quality).

My next question would be how failing to survive a "high-energy test" compromises safety (if the meter does not completely explode, of course).

This has been discussed before, but no one can agree on how relevant the safety precautions are.

There can be dangerous power surges in the mains due to nearby lightning strikes or faults in the distribution system that allow high voltages to jump over onto the low voltage side. The usual impact of this is to damage equipment in your house like televisions or computers, or in the worst case to set your house on fire.

Now you have to ask what is the probability that such an event will occur while you are probing the mains with your meter? In my case since I measure the mains for maybe a few seconds in any given year (about 0.00005% of the time) I would say the probability is essentially zero that I will ever encounter a dangerous surge while using a multimeter. Especially since I am not likely to probe the mains during a lightning storm.

If someone is an electrician who uses the meter every day as part of their job, then the probability is different. If I were using a meter at work I would want a safe meter.

A different question is static electricity. I can certainly build up a charge while walking across the carpet. Most things I touch are not damaged by this, but a meter is different. It has metal probes that are specifically designed to carry electricity inside the meter and apply it to the internal circuits. So in the unlikely case that I pick up a big charge and then touch the metal part of the meter probe, I could potentially fry the meter. Here I would agree that protection is warranted for a typical home user.

[Fungus]

My next question would be how failing to survive a "high-energy test" compromises safety (if the meter does not completely explode, of course).

That's the thing - they often do explode. Watch the videos in this thread, I wouldn't want to be holding one in my hand when they go off.

Even if they don't explode they might be damaged internally and give false readings or catch fire next time you connect them to mains voltage.

Or ... the cheapo cables could melt (never wrap cables around your hand, just in case).

Under what conditions? Lightning strikes aside; any large inductor can generate many thousands of volts if it's suddenly disconnected on one side. Do you know what your neighbor is doing in his garage right now?

[joeqsmith]

Not too long a member posted about doing some wiring in their RV and going across the lines with the meter in the current mode.    We have seen a few posts here about the MOTs.  There was the tractor magneto. Funny when you start to think about the ways people have damaged their meters. 

With some of the crap meters I have looked at where they share the current and voltage input then toss a glass fuse in there with it, that we don't here some better stories. 

Fluke has some good info on their website.   I've posted a few links in this thread.  You could Google "ABCs of multimeter safety - Fluke"

Maybe read the following:
https://www.lanl.gov/safety/electrical/docs/electrical_measurement.ppt#32

The PDF linked here may be of interest as well
http://gps.sozialnetz.de/go/id/pn/

[exe]

Fluke has some good info on their website.

Thank you for the links. I read them, but I don't trust them. We too have a marketing department that weekly writes scary articles to pursue people to use our services. And, despite Fluke wildly insists, I don't care if my DMM to survives a 10kV transient. I want to survive it, but I don't really care about equipment. But two things I learned from that docs: 1) do not use crappy probes 2) be careful with inductive loads. Still not clear how I can get damaged in other cases. I can only think of a case that the arc gets through the DMM's body.

That's the thing - they often do explode. Watch the videos in this thread

No, that's the author makes them exploding. How many meters actually exploded just by connecting to mains? That's my question: how dangerous they are when you don't try to "measure" 3kV pulses on purpose and use proper probes. It doesn't mean I'm proposing to abandon you flukes, guys, and replace them with Mastech or Uni-T. I'm not saying this. Please keep burning multimeters. I just want to understand how real the threat is.

Some scientific date would be nice. Like,  10% of Mastech customers die annually because of electric shock. Or, Fluke users live 10 years longer and have less changes of divorce. Or at least some statistics how many transient a typical household has (I found no such date).

There can be dangerous power surges in the mains due to nearby lightning strikes or faults in the distribution system that allow high voltages to jump over onto the low voltage side. The usual impact of this is to damage equipment in your house like televisions or computers, or in the worst case to set your house on fire.

I was waiting for this comment . To my mind, home equipment is much less protected from power surges than an "average" multimeter. So I think for an average hobbyist there is more danger to get killed/injured by a dishwashing machine, or a microwave, or a faulty phone charger. Or by my DIY power supply, which only has a conventional toroidal transformer to protect me from mains (and maximum isolation voltage not even specified).

[Fungus]

I was waiting for this comment

Nobody's saying you're definitely going to die. The combination of events needed to blow up your multimeter when it's connected to the mains at home is very unlikely.

OTOH so are the chances of dying in a car crash. I bet your car has seatbelts and airbags though. 

How many meters actually exploded just by connecting to mains?

Enough that they eventually developed some standards and safety ratings.

[tautech]

To exe and others, this entire thread and all Joe's vids need to be studied to fully comprehend the robustness and safety aspects Joe has enlightened us all about.
Early on Joe mentioned he had lost faith in Fluke meters after one he owned expired from static damage.....it was news to me that meters could be so easily damaged  and I've been a close watcher of Joe's work since.
His tests are now more advanced and refined from those days and now when he lines DMM's side by side we have a very good look at how they compare against one another.

Joe's work will live on for decades here and to be found by others and we all owe him a depth of gratitude for the issues he has raised and explored for the benefit of us all.

Edit
In the time that it takes write a reply to challenge findings or opinions one could have read a good # of posts in this thread and learnt something.

[joeqsmith]

I have a ceiling fan and needed to replace its switch.  Drove to all the local stores and could not find one switch that was UL rated.  This switch has the potential to cause an electrical fire.  I would GLADLY pay for a good certified switch but there are none to be had.   We do not make them here anymore that I have found.   I doubt the average consumer will care unless something happens.  Even then my guess is the finger would be pointed at the installation and not the switch itself.  There used to be public service announcements to help educate the general population about things like UL.  Now we talk about quality rather than practice it.  Fan I would guess is I would imagine nearing 40 years old now.  The larger white switch is make by KTE and was the original The smaller switch is what I used to replace it.  Note the CSA and RL marks on it.  The pull mechanism in this switch failed in maybe 5 years or so.  That's how bad the quality is.   The new switch is even cheaper made with no cert.   

Keeping stats like this I'm sure is a mental illness of sorts, like stamp collecting.
 
About home appliances, they have their own safety ratings, for now.  Like the switch, I am not suggesting all the crap we import is certified for safety.  The outside metal cases are grounded.  Double insulation, single ground point.  Bond wire testing.  HI-POT testing.   Nothing like a hand held device you would hold in your hand while you are probing mains.  Not that someone could not rewire their microwave to short the two lines together while the covers are off with no fuse in place, but I have seen a few crap meters that had no fuse where someone could easily do just this, short the lines.   And even if you did own a meter that had HRC fuses to help protect you, nothing prevents you from being stupid and shorting out the fuse with a wire.   

Again, I have little to no interest in multimeter safety because I do not work in an industry where it concerns me and I know enough to limit my own risks at home.   

If I Google "electrical fatality statistics", there's all sorts of information that comes up.  I added the word "multimeter" to the search (this stuff is not rocket science).  Now here is an interesting article. Could be a fear based ad still.

http://iaeimagazine.org/magazine/2008/07/16/multimeter-accident-prevention-plan-an-electrical-inspectors-survival-guide/

[mzacharias]

If I repaired consumer products or just considered how often my own AC line powered equipment has been damaged in my house over my lifetime, would I somehow feel it relates to what can happen through out the world under all conditions?   Would I ever suggest that any of the testing I show has anything to do with how safe a meter would be if exposed to a real surge condition?  Of course not.   

I would imagine there are people who believe jumping a fuse with wire is an acceptable practice for all environments. It may very well be a person could be fine in their little bubble.     

My interest has always been in low energy robustness.  That's why I make a bigger deal about the EMC than the safety standards.  It's not that I don't care about safety as much as it is rare I am at risk in the home hobby lab.

I can understand owning an expensive meter like the 87V, having total confidence in it and then with all your love for the meter, someone comes along and shows that it can be damaged at levels that many low cost meters also fail at.  Rather then simply acknowledge it, you choose to defend it and claim the tests have nothing to do with what you do in real life.  That's all fine.  I see the same response from many of the meters I run.  I would expect that if I ran Dave's 121GW and it failed the puny grill starter test, Dave would defend that the test was pointless and not how it is conducted in the real world. 

But again, that's not why I run the tests.  I have no love for any meter. I would toss the Brymen aside if I found something I liked better.  I run them against a standard to see how electrically robust they are with one another.  I can't help it if you feel Fluke got a bad shake in the testing. I run the test and present the findings. If you have no interest in watching the videos and feel there is nothing you can learn from them, to be honest I don't understand why you are wasting your time with them.

My intention was not to diminish your tests or your results, but I do think my question was valid on it's own. Possibly it might have been better posted in another context. By all means do keep it up and I don't feel I'm wasting any time watching your videos.

And as for learning - there's no doubt in my mind your training and experience is an order of magnitude better than mine, if not more.

I do cringe a little at some of your tests...

[joeqsmith]

...

I bet your car has seatbelts and airbags though. 
...

Enough that they eventually developed some standards and safety ratings.

And don't forget HRC fuses that I recently was schooled on how they can easily be replaced with wire.   I do like the slot cut into the case to allow for maybe an external power supply.  Good stuff. 

[IanB]

I have no problem with appropriate levels of safety and robustness, but requirements should be measured against the actual levels of danger in the environment.

For instance, I measure things related to electronics on the workbench, either battery powered or isolated from the mains. If protection devices made a meter less suitable for those measurements, I would rather my instrument didn't have such protection devices. A fuse, for example, increases the burden voltage on current measurements. I have never blown a meter fuse, and I never intend to. Why do I need one? Let me choose a meter with a fuse for electrical work, and a meter without a fuse for electronic measurements.

The mains. Why do I care? I measured it once and it was 120 V AC at 60 Hz. What a surprise! Do I never need to measure it again? If I am doing electrical work around the house, I care if the power is disconnected or not. For that I should use a voltage test device. A multimeter is not the right tool for that job. Very occasionally I might care about continuity. So yes, a continuity meter is good, after I have verified the power is off.

Sadly, all the safety codes and regulations are designed to guard against the ignorant, the people who don't know what they are doing. This is called "the nanny state". It's a shame, but I guess we have to live with it.

[tautech]

Yes Ian, we need protecting from ourselves when we know no better.

There are very common use cases where a DMM might also be exposed to unexpected transients, the first to mind would be the collapsing field (back EMF) from a relay coil or similar.
It might only have a low voltage applied to it but interrupt the supply and you could be in for a shock and a buggered DMM.
How high could the back EMF event be.....as high as it needs to be to find a discharge path. 

[joeqsmith]

My intention was not to diminish your tests or your results, but I do think my question was valid on it's own. Possibly it might have been better posted in another context. By all means do keep it up and I don't feel I'm wasting any time watching your videos.

And as for learning - there's no doubt in my mind your training and experience is an order of magnitude better than mine, if not more.

I do cringe a little at some of your tests...

I am not a repair tech nor am I an electrician.  I am open to discussing your thoughts about the testing I have done.  It's not like there is a pool of information where there are industry standards on how to benchmark meters for their electrical robustness.  This is what happens when you take a simple idea like "I wonder if a cheap $50 meter is more robust than a $400+ meter" and act on it.  Because it's not something that is commonly done (maybe never) it leads to confusion.  Then we have the internet with it's vast pools of experts on the mater.  After a couple of years, it seems we have heard it all. 

There is little you or anyone could post that would diminish the testing I have done to date.  It's just data to me that I collect it and present.  Everything is open as far as what I have done.  If you feel your 87V is "reliable and consistent, and safe. Period"  that's all fine.  Your personal feelings do not go against anything in the data I have shown for the 87V.  I have never collected data for safety or reliability.  Nor have I studied what I would consider makes a meter consistent.  So I won't disagree with you as I have no data that says otherwise.   

I am only looking electrical robustness and the 87V is just not very robust when compared with some of the other meters I have looked at.  I will give you that the 87V is way more robust than the UNI-T's that failed the puny grill starter test.  That has become a standing joke around here.  Even my wife will ask, "did it fail the grill starter"  

What's to cringe at?     The energy levels are fairly low, I have a fair amount of safety checks built into the generator and if I play with something that may pose a high risk it's behind a half inch thick plate of Plexiglas (more to protect the camera).   Any time I play with the half cycle generator, I am a fair way away and out of the direction of the blast.  The risk is low for me but it's not something I would suggest the fuse jumping crowd get involved with.   

https://www.copeplastics.com/plexiglas-impact-resistance.html

[joeqsmith]

Sadly, all the safety codes and regulations are designed to guard against the ignorant, the people who don't know what they are doing. This is called "the nanny state". It's a shame, but I guess we have to live with it.

IMO, it has a lot to do with trade as well.   

[MacMeter]

I have a ceiling fan and needed to replace its switch.  Drove to all the local stores and could not find one switch that was UL rated.  This switch has the potential to cause an electrical fire.  I would GLADLY pay for a good certified switch but there are none to be had.   We do not make them here anymore that I have found.   I doubt the average consumer will care unless something happens.  Even then my guess is the finger would be pointed at the installation and not the switch itself.  There used to be public service announcements to help educate the general population about things like UL.  Now we talk about quality rather than practice it.  Fan I would guess is I would imagine nearing 40 years old now.  The larger white switch is make by KTE and was the original The smaller switch is what I used to replace it.  Note the CSA and RL marks on it.  The pull mechanism in this switch failed in maybe 5 years or so.  That's how bad the quality is.   The new switch is even cheaper made with no cert.   

Keeping stats like this I'm sure is a mental illness of sorts, like stamp collecting.
 
About home appliances, they have their own safety ratings, for now.  Like the switch, I am not suggesting all the crap we import is certified for safety.  The outside metal cases are grounded.  Double insulation, single ground point.  Bond wire testing.  HI-POT testing.   Nothing like a hand held device you would hold in your hand while you are probing mains.  Not that someone could not rewire their microwave to short the two lines together while the covers are off with no fuse in place, but I have seen a few crap meters that had no fuse where someone could easily do just this, short the lines.   And even if you did own a meter that had HRC fuses to help protect you, nothing prevents you from being stupid and shorting out the fuse with a wire.   

Again, I have little to no interest in multimeter safety because I do not work in an industry where it concerns me and I know enough to limit my own risks at home.   

If I Google "electrical fatality statistics", there's all sorts of information that comes up.  I added the word "multimeter" to the search (this stuff is not rocket science).  Now here is an interesting article. Could be a fear based ad still.

http://iaeimagazine.org/magazine/2008/07/16/multimeter-accident-prevention-plan-an-electrical-inspectors-survival-guide/

The article you linked to, was worth reading. I was unaware of "fused" test leads. While probably not desirable in electronics work, certainly worth considering for high voltage electrical jobs.

http://www.epanorama.net/newepa/2011/12/29/fused-multimeter-probes/

https://www.amazon.com/Fluke-SureGrip-Degree-Operating-Temperature/dp/B005GFLCGK?th=1

Unfortunately, the last statement in the article (1st link):

"People buying cheap meters typically wouldn’t be interested in spending more than the cost of the meter on leads. Sadly, safety is often overlooked."

[P90]

...

I can always count on you adding to the technical discussion.     Did you need to add or remove a period? 

I posted a link to a picture of a nasty exploded glass fuse inside a meter... then I thought it might not be such a good idea, and I couldn't delete the post...

[exe]

Thank you very much, guys, for comprehensive answers. Now got my own opinion on the subject.

[Wytnucls]

They had to remove the carpets on the ISS:

[Fungus]

They had to remove the carpets on the ISS:

It's all extra weight, and accidentally dropping one isn't much of an issue up there.

[Fungus]

Magnetic hangers, too. They're actually a safety feature, to free up a hand and get the meter a bit further away.

And of course you're supposed to wear gloves and safety glasses, too.

[IanB]

They had to remove the carpets on the ISS:

It's all extra weight, and accidentally dropping one isn't much of an issue up there.

I think Wytnucls meant to reduce the danger of static electricity blowing up the meters...

[mzacharias]

My intention was not to diminish your tests or your results, but I do think my question was valid on it's own. Possibly it might have been better posted in another context. By all means do keep it up and I don't feel I'm wasting any time watching your videos.

And as for learning - there's no doubt in my mind your training and experience is an order of magnitude better than mine, if not more.

I do cringe a little at some of your tests...

I am not a repair tech nor am I an electrician.  I am open to discussing your thoughts about the testing I have done.  It's not like there is a pool of information where there are industry standards on how to benchmark meters for their electrical robustness.  This is what happens when you take a simple idea like "I wonder if a cheap $50 meter is more robust than a $400+ meter" and act on it.  Because it's not something that is commonly done (maybe never) it leads to confusion.  Then we have the internet with it's vast pools of experts on the mater.  After a couple of years, it seems we have heard it all. 

There is little you or anyone could post that would diminish the testing I have done to date.  It's just data to me that I collect it and present.  Everything is open as far as what I have done.  If you feel your 87V is "reliable and consistent, and safe. Period"  that's all fine.  Your personal feelings do not go against anything in the data I have shown for the 87V.  I have never collected data for safety or reliability.  Nor have I studied what I would consider makes a meter consistent.  So I won't disagree with you as I have no data that says otherwise.   

I am only looking electrical robustness and the 87V is just not very robust when compared with some of the other meters I have looked at.  I will give you that the 87V is way more robust than the UNI-T's that failed the puny grill starter test.  That has become a standing joke around here.  Even my wife will ask, "did it fail the grill starter"  

What's to cringe at?     The energy levels are fairly low, I have a fair amount of safety checks built into the generator and if I play with something that may pose a high risk it's behind a half inch thick plate of Plexiglas (more to protect the camera).   Any time I play with the half cycle generator, I am a fair way away and out of the direction of the blast.  The risk is low for me but it's not something I would suggest the fuse jumping crowd get involved with.   

https://www.copeplastics.com/plexiglas-impact-resistance.html

I just cringe at the impending destruction of a perfectly decent (for most of us anyway) meter. It's cool you're able to fix most of them however.

[joeqsmith]

I just cringe at the impending destruction of a perfectly decent (for most of us anyway) meter. It's cool you're able to fix most of them however.

If you would have taken the time to look at the on-line spreadsheet, in the first set of tests I ran 13 meters.  Of these, 3 were repaired and 1 survived without damage.  When I changed to the new generator, I have ran 40 meters.  Some of these were damaged during the first tests and had been repaired.  Of these, 13 where undamaged or repairable. 

The few that have had no detectable damage to date are the Fluke 101, 115 and the Brymen BM235.  The HIOKI DT4252 was right there.  Also, no other meter has withstood the levels that 5KY's Fluke 107 was exposed to.  The 107, even though its damaged, has proven to be the most robust of the meters I have looked at.  Of course all that data is on-line.

So roughly 30% recovery is all.  Certainly not what I would consider most.  Normally the lower end meters just don't have enough protection to save the custom IC.  Of the meters I keep, I have no use for the vast majority of them beyond using them as a visual comparison against other meters.  Once they have been stressed, they really have no value.  I would not give them away because of the risk.  A member did ask for a few parts off one once which I took the time to strip and send to them.  Not even a simple thank you. 

I have a job, pay taxes and buy these meters out of pocket.  There's no handouts and I am certainly not asking for any.  No one pays me to do these reviews.  I don't work for a company that produces, distributes or sells handheld meters of any kind.  My interest is in seeing how the meters compare with one another and that means running them to failure.

I understand there being people who can't afford a meter.  Although I have no idea why they would be wasting time on their cell phones watching my videos. I certainly understand wanting to feel good about the items you buy, especially when you feel you are buying high quality products and paying a premium.  If you don't want to know how the meters compare, the best thing is just not watch.  There are reviews where people just talk about the input circuitry and then give you their opinions.  I doubt you would find a bad review of the 87V if this is all you are after.