EEVblog Electronics Community Forum
Products => Other Equipment & Products => Topic started by: harry66 on January 20, 2011, 09:42:04 am
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Hi,
when browsing the web for a new multimeter (after my experiences with DM620 - oh my...) I found an interesting video on a manufacturers Website.
Gossen Metrawatt presents this as a warning to their future customers to keep hands off meters that don't a have a security certification. In Germany (wher I live and Gossen produces) this certification is done by the VDE for devices related to electric hazard potential.
Have a look at the video and make up your mind, what devices to keep your fingers off!
http://www.gossenmetrawatt.com/deutsch/seiten/achtung-gefaehrlichemultimeter.htm (http://www.gossenmetrawatt.com/deutsch/seiten/achtung-gefaehrlichemultimeter.htm)
Guess this can not be said often enough. Bear with me if this link has been posted already.
Cheers
Uwe
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Must say I'm suspicious of this type of video as they could be applying anything to the meter - I bet I could make a Fluke or pretty much any meter do that with sufficient voltage.
If Dave wants to send me one I'd be happy to give it a try.. 8)
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We have several discussions about safety in multimeters in past eevblog discussions. Just search keyword "multimeter safety."
Here's one, with more videos.
This includes design, certification and testing issues.
https://www.eevblog.com/forum/index.php?topic=383.60 (https://www.eevblog.com/forum/index.php?topic=383.60)
https://www.eevblog.com/forum/index.php?topic=1423.60 (https://www.eevblog.com/forum/index.php?topic=1423.60)
https://www.eevblog.com/forum/index.php?topic=1757.msg24434#msg24434 (https://www.eevblog.com/forum/index.php?topic=1757.msg24434#msg24434)
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Must say I'm suspicious of this type of video as they could be applying anything to the meter
Hi Mike,
you are right: Give it the right voltage and it's hot air. But that doesn't make any sense.
What makes more sense is that you can connect 1kV in any connector combination and it will only blow a fuse. A bad one might even be damaged but won't burn your fingers. I am not going to discuss what makes sense and what doesn't.
I don't think it makes any sense to speculate on how they could bring special effects on a meter. It is more like what they experience in real life in their certification lab.
So take it serious and save that comment for the fun thread. ::)
/Uwe
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So take it serious and save that comment for the fun thread. ::)
Well I prefer the Fun thread as an way to deal with such information , or else you are promoting VDE certifications, and you expect to make money from that !!
And by the way , non of the tests that are made in a "certification progress" ,
had anything to do with " every day life ".
Saturation had posted interesting links , read them.
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Must say I'm suspicious of this type of video as they could be applying anything to the meter
Hi Mike,
you are right: Give it the right voltage and it's hot air. But that doesn't make any sense.
What makes more sense is that you can connect 1kV in any connector combination and it will only blow a fuse. A bad one might even be damaged but won't burn your fingers. I am not going to discuss what makes sense and what doesn't.
I don't think it makes any sense to speculate on how they could bring special effects on a meter. It is more like what they experience in real life in their certification lab.
So take it serious and save that comment for the fun thread. ::)
/Uwe
I think he is taking it seriously. His point was that the video is more or less eye candy (or gossen metrawatt marketing material) and nothing more since it could be 50 kV coming into that meter for all we know. I have a feeling that was probably quite a bit more than 1 kV. I can't read german though so maybe it says.
Meter safety has been discussed here quite extensively. Saturation has provided the links to the threads.
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I'd argue that video is sensationalist because I don't think it's plausible you'd see a failure mode like that even on the crappiest meter as a result of connecting to anything a non-expert user would be likely to have access to - i.e. normal mains voltages.
Looking at the linked report:
http://gps.sozialnetz.de/global/show_document.asp?id=aaaaaaaaaaaajxn (http://gps.sozialnetz.de/global/show_document.asp?id=aaaaaaaaaaaajxn)
Translation without graphics :
http://translate.google.com/translate?js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&sl=de&tl=en&u=http%3A%2F%2Fgps.sozialnetz.de%2Fgo%2Fid%2Fpn%2F&act=url (http://translate.google.com/translate?js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&sl=de&tl=en&u=http%3A%2F%2Fgps.sozialnetz.de%2Fgo%2Fid%2Fpn%2F&act=url)
They tested 105 meters costing 3 to 65 Euro, and 100% had some safety issues, with 63% serious enough to warrant a recall
Some are obvious from the images in the report.
AFAICS the main problem is these meters stated they were capable of use up to 1KVDC, which is what I suspect the one in the video was subjected to, but not something the avarage unskilled user is likely to encounter.
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Try connecting a meter to two microwave oven transformers wired in series and see what happens.
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Try connecting a meter to two microwave oven transformers wired in series and see what happens.
Even most fully approved meters would have a problem with that.
And anyone using a cheap meter in those circumstances is an idiot - it doesn't make the video any less of a cynical marketing scare tactic.
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And anyone using a cheap meter in those circumstances is an idiot - it doesn't make the video any less of a cynical marketing scare tactic.
beautiful description and I agree ..
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Try connecting a meter to two microwave oven transformers wired in series and see what happens.
Even most fully approved meters would have a problem with that.
And anyone using a cheap meter in those circumstances is an idiot - it doesn't make the video any less of a cynical marketing scare tactic.
Are you sure?
A typical microwave oven transformer puts out 2kV so two in series is 4kV, which is 5.65kV peak. Yes maybe a meter will be tested to handle short pulses of that voltage level but it doubt it will be able to withstand continuous abuse.
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They tested 105 meters costing 3 to 65 Euro, and 100% had some safety issues, with 63% serious enough to warrant a recall
Some are obvious from the images in the report.
Unfortunately there is no detailed list, it would be interesting if there was one ..
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It looks that we got again at the HV paradise , and the life with more than 1000 Volts ..
Its time for an commercial break ...
GET THIS Superb Fluke Probe , if your demands for measurements are at 1000 to 40.000 Volts ;D
(http://img827.imageshack.us/img827/7558/flukemodel80k4002.jpg)
I did !! :D
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You can see from the way the test leads flinch from electromagnetic force when they turn on the juice they are passing a huge current almost certainly through the unfused 10A current range on the meter.
So enough current to melt the meter 10A shunt in a second but not enough to blow any fuse in the supply and enough voltage to keep the shunt arcing after it melted.
My old Fluke 77 has no fuse on the 10A range and would fail perhaps as spectacularly, doesn't bother me. I just remember not to measure the voltage on bus bars with 200A+ fuses with it plugged into the 10A current range.
In real life you are more likely to blow a fuse in the supply or the end off the probe without causing any damage to the meter.
Artificial conditions used to demonstrate the limited benefit of an expensive and burden increasing fuse in a meter 10A current range IMO.
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If a meter is claimed to be good for a particular CAT rating, and you put the test voltage for that CAT rating through it, and it catches fire, it is shit. There is nothing wrong showing the word that it is shit. The big Chinese vendor could certainly have sued Gossem over the video if they think it is unfair.
The big issue with these crap meters is that they end up in the hands of laymen, because they are so cheap. I have seen the shit sold at supermarkets in the home-improvement section. Between wall paper and paint a selection of crap multimeters with a range going up to 250 Volt or even 600 V or 1.2 kV. The laymen looks at the range, if at all, and has no clue about CAT ratings, fake CAT ratings and fake safety marks.
Not to long ago I had an argument with a neighbor, who was proudly showing of his *shudder* analog *shudder* Protek HC5050E. Not even a CAT rating, but it had a CE mark. Well, or maybe an Chinese Export mark. The highest DC range was 1.2 kV, the highest AC range confusingly labeled P-P Up 840, and a separate socket even labeled P-P 3300 AC 1200V.
3.3 kVpp AC in that cheep plastic case, sure.
And the best of it were the probes. The probes had no rating, too. The wires were sold to the metal tips and the tips loosely screwed into cheap plastic housings with no strain relieve. Normal wear and tear and the wires will at some point come loose and you end up with a blank wire in your hand. Just hope you don't have the other end connected to something > 48 V.
Less than 30 € buys you this engineering wounder from Hung Chang Co. Ltd.
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And anyone using a cheap meter in those circumstances is an idiot
Professionals using crap meters or just promoting them are idiots.
Laymen using crap meters just don't know better. They trust the Chinese "engineers" and retailers that they get something which is safe to use. Unfortunately it isn't.
It is the job of professionals to disencourage laymen from using crap. Promoting crap meters is simply unprofessional and maybe indicates a lack of proper training of the "professional".
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You can see from the way the test leads flinch from electromagnetic force when they turn on the juice they are passing a huge current almost certainly through the unfused 10A current range on the meter.
I suspect the test was HVDC, in which case an inadequate fuse could arc over,and being DC the arc wouldn't quench like it does with AC - heat/fire like that will be more likely be from moderate impedance (arc/carbon tracking) than a low impedance like an unfused shunt as the former will dissipate a great deal more power.
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It has been said before, the multimeter's have been tested in a market surveillance.
The tests were performed by a conjunction of the Ministry of Social Affairs of Hesse (which is charged with product and market surveillance, and also published the report) at state level and one of our trade associations (fine mechanics and electronics). Actually the correct translation seems to be "Employer's liability insurance association", they are charged with accident/casulty insurance, the writing and enforcement of safety rules and other things. They have powers quite similar to OSHA in the USA as far their trade is involved.
They tested the Multimeter's according to the applicable standards. Standards that /must/ be met if you sell them in the EU.
So if the multimeter stated 1000V they used this to pick the right test, usually with flamboyant results like in the video.
No need to whip up a marketing scare if real world test results turn out the way they are.
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Must say I'm suspicious of this type of video as they could be applying anything to the meter - I bet I could make a Fluke or pretty much any meter do that with sufficient voltage.
Nothing suspect about the video, this is simple in-bounds VDE testing to make sure the meter meets the CAT specs.
Dave.
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Amazing as it may be, there are still skeptics of multimeter safety. My theory is that some people just can't imagine electricity doing anything other than shocking you. Maybe you have to see an electrical explosion in real life to believe that it can happen.
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For everyone thinking Gossen set this up by deliberately using a very high voltage, note that IEC61010 requires equipment to safely handle transient voltages of up to 8kV with an extremely low output impedance, depending on CAT rating and voltage. And these tests are based on the kind of available energy in real high-power circuits. And yes, this includes the amps jack (ever wonder why Fluke/Agilent use those expensive fuses?). The original Fluke 77 was not IEC(6)1010 rated, so it didn't have to conform to those specs. Multimeter safety has actually improved since then, it's not just marketing and a flashier case.
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For everyone thinking Gossen set this up by deliberately using a very high voltage
The video its not made by Gossen .
Gossen just demonstrate it , so to gain public trust.
And if we agree that some DMM are not build for industrial use , our life will become easier.
And even better , if we do an local list , of the true Industrial multimeter's at the year 2011 ,
we will help more people about avoiding the average lower specs ones.
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My theory is that some people just can't imagine electricity doing anything other than shocking you.
That's True ... :)
The young ones gets very excited by all those sparks and flames.
But personally , especially now in my second youth, the only message that I can pass as " experience threw the years " ,
will be this : If you respect the electricity when you get near it, you have nothing to afraid.
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Also know when you are out of your depth.
DIY with little to no knowledge is can be fun, but if you are playing with stuff that will kill you or your loved ones at least fake that you are thinking for a moment.
Electricity, gas but also harsh cleaning chemicals fall into that area.
There are some professional cleaners that will really mess you up if you stint on personal safety equipment. Say descalers that use Hydrofluoric acid as active agent. So better know what a material safety data sheet (MSDS) is and how to use it because that is where you'll find that bit of information...
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Also know when you are out of your depth.
That's the hard part my friend .
Only the experienced have the sense to know their depth , end even so they have awareness about the 90% top.
There is always unpredicted dangers, but we can not stay locked in our homes because of them.
But the young ones , are the something else , I can not forget one, who showed up saying that he tried to measure an electric fence,
with his new multimeter .. ( Yes the multimeter fried )
But the point is , that he had the wild idea , and no one to stop him from doing it.
And so I think that the grownups , they should always watch their kids.
The warnings from the Internet and forums , its an positive thing , but the true responsible for such matters are always the parents.
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For everyone thinking Gossen set this up by deliberately using a very high voltage, note that IEC61010 requires equipment to safely handle transient voltages of up to 8kV with an extremely low output impedance, depending on CAT rating and voltage. And these tests are based on the kind of available energy in real high-power circuits. And yes, this includes the amps jack (ever wonder why Fluke/Agilent use those expensive fuses?). The original Fluke 77 was not IEC(6)1010 rated, so it didn't have to conform to those specs. Multimeter safety has actually improved since then, it's not just marketing and a flashier case.
Actually, if your meter is rated to 1000V CATIV I believe 61010-1 calls for a 12kV pulse.
Neil
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Actually, if your meter is rated to 1000V CATIV I believe 61010-1 calls for a 12kV pulse.
You may be right. Last time I checked, no common DMM went beyond CAT IV 600V, but that was a number of years ago.
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A bottom line in DMM safety it should meet the safety ratings of its highest voltage range. If a cheapo has 1000Vdc or AC range, it must be able to pass the CAT rating for that range.
It doesn't even discuss the ratings of the probes, which is not tested. Even if you have CAT rated probes but they have been abused or worn, they can still fail.
AFAIK, no agency in the US enforces CAT ratings except OSHA. The main target of untested meters is consumers, at least in the US, and the only way to seek redress for injury is a personal injury suit. Likewise, in work related injuries, an employer who doesn't specify and make reasonable enforcement of DMM safety, is liable to both OSHA [ criminal neglect] and a personal suit by the employee [civil complaint].
So far the injuries are rare, but its so easily avoided why gamble with your body parts or life? Safety should be taught as a way of life, not as an afterthought.
FWIW, a single trip to the ER in the USA, without treatment is $500 [just to evaluate and see what you need]. Reasons for well being aside, its not cost effective if you misuse a meter without safety features.
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Amazing as it may be, there are still skeptics of multimeter safety. My theory is that some people just can't imagine electricity doing anything other than shocking you. Maybe you have to see an electrical explosion in real life to believe that it can happen.
I think most believe it can happen, they just believe it can't happen to them because they aren't working in a substation or something.
The thing they fail to understand is once you touch any aspect of the mains, you have a potential (no pun intended) high energy source that can surge at any given time.
Dave.
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Last night I had see on TV , one story about the large American airplanes , with aged electrical wiring,
that they have problems after 15 - 20 years of use , and the companies they do not replace then !! because it cost allot , and if 4-5 airplanes fall and crash because of it every year ... it called as " cost of doing business ".
Luckily about the electrical measurements , the risk goes 100% at the one who does the job.
And about how strictly he will follow the rules , its his own personal choice.
By the same way of thinking , if some one are so strict about security and health maters,
he must never get aboard on an airplane, ever !!
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By the same way of thinking , if some one are so strict about security and health maters,
he must never get aboard on an airplane, ever !!
Still safer than cars by a long shot, not sure how occupational hazards compare. It's also about costs/benefit. The price of a good DMM is a few hundred dollars, which you can use for many years. The costs (in time) of taking the boat/train instead of flying, or changing jobs/vacation destination, is likely to be much higher.
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Your diplomacy does now work here :P
And I was aware that there was no hope to agree with me,
and so I am not surprised .. :)
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It doesn't even discuss the ratings of the probes, which is not tested. Even if you have CAT rated probes but they have been abused or worn, they can still fail.
Probes, leads and accessories for test and measurement equipment are also covered by IEC61010. Probes and probe assemblies are covered by IEC61010-031. If a manufacturer claims it complies to IEC61010 then the probes supplied with the instrument must have been tested and rated correctly.
IEC61010 edition 3 was released last year and currently manufacturers are revisiting instruments and probes to test if they comply to the new standard - so expect that DMMs and spares will all change over the next 18 months or so.
Yours
Neil
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IEC61010 edition 3
IEC 61010-1 ed3.0
http://webstore.iec.ch/webstore/webstore.nsf/standards+ed/IEC%2061010-1%20Ed.%203.0?OpenDocument (http://webstore.iec.ch/webstore/webstore.nsf/standards+ed/IEC%2061010-1%20Ed.%203.0?OpenDocument)
There it is 322 pages PDF !!
But even so, practically the what ever changes will touch the market after 3-4 years. (practically) .
We have many examples of some rules , that (practically) was not usable.
End so it will not be an mystery to me, if there will be any IEC 61010-1 ed3.0a ,
that sorts out such cases.
Oh my , it looks that even the document has an price of 300 CHF (Swiss francs),
or 312$ ..
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I think people forget that the mains can unleaser some high power and when you pump power/heat into a confined space things start to expand fast. after all gunpowder on its own just burns violently, encase it and then set light to it and the sudden presure in the confined space produce an explosion, same with pumping power into small items
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IEC61010 edition 3
IEC 61010-1 ed3.0
http://webstore.iec.ch/webstore/webstore.nsf/standards+ed/IEC%2061010-1%20Ed.%203.0?OpenDocument (http://webstore.iec.ch/webstore/webstore.nsf/standards+ed/IEC%2061010-1%20Ed.%203.0?OpenDocument)
There it is 322 pages PDF !!
But even so, practically the what ever changes will touch the market after 3-4 years. (practically) .
We have many examples of some rules , that (practically) was not usable.
End so it will not be an mystery to me, if there will be any IEC 61010-1 ed3.0a ,
that sorts out such cases.
Oh my , it looks that even the document has an price of 300 CHF (Swiss francs),
or 312$ ..
There is always a transition period when a new standard comes out, usually three years. In Europe, the date of adoption is is when the standard is published in the Official Journal. The new standard includes things that were not considered on the previous standard, the main one being rules for insulation on multi-layer PCBs.
Each time we produce a new instrument at work, someone has to sit down and go through that document clause by clause and produce a report to say that the product meets each point, test or requirement.
As for the edition 3.0a - I jolly well hope so as there is a monumental inconsistancy in two to the tables relating to mains clearance. It appeas that someone has transposed a couple of digits and it made its way through all the committee stages, ( there were at least 2 CDVs that I know of) without being spotted. We spotted it at work when working out a spreadsheet to calcultate creepage, clearance and test voltages.
Neil
Edit
CDV is a code used for standards work. It stands for Committee Draft for Voting. Basically, when it reaches this stage a draft standard is sent around all the members and they can either accept the draft or reject it. The votes are tallied and if the magic number is reached the standard is accepted, if not it all starts again