Author Topic: Multimeters that do not appear to meet their safety specs. (updated frequently)  (Read 146145 times)

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Offline Neilm

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There are different revisions of IEC61010 and Uni-T maybe did actually meet an older version.

But if it is still on sale in Europe, it must comply with the 3rd edition - the fact it was designed to meet the second edition before the 3rd was published is irrelevant.
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Offline Wytnucls

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The version sold in Europe has been upgraded to meet the latest requirements. The PCB has been revised and it has the 1000V HRC fuses. Previous versions are now illegal, unless part of old stock imported before the deadline.
 

Offline MoighonFweeman

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Quote
Extech EX330   CATIII/600V CATII/1000V  Current ranges have glass fuses rated for 250V with no warning of lower voltage (Submitted by T4P, reviewed by Dave Jones) Additional information and reviews on different Extechs show that Extech EX series are to be avoided in general. The quality control appears to be so bad that parts are coming loose inside some meters from the factory, amongst other problems.

I do agree with the statement that Extech does not quite meet expectations when it comes to quality control. However, it seems to me that the probes, and not the multimeter itself, are rated for those CAT ratings. Unless it claims somewhere in the documentation that the multimeter is also rated for up to 1000V? That would be silly.
 

Offline PedroDaGr8

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Quote
Extech EX330   CATIII/600V CATII/1000V  Current ranges have glass fuses rated for 250V with no warning of lower voltage (Submitted by T4P, reviewed by Dave Jones) Additional information and reviews on different Extechs show that Extech EX series are to be avoided in general. The quality control appears to be so bad that parts are coming loose inside some meters from the factory, amongst other problems.

I do agree with the statement that Extech does not quite meet expectations when it comes to quality control. However, it seems to me that the probes, and not the multimeter itself, are rated for those CAT ratings. Unless it claims somewhere in the documentation that the multimeter is also rated for up to 1000V? That would be silly.

Where would you get that idea?


If you look at this image, above the right jack you can clearly see CATIII 600V CAT II 1000V. So clearly that is what they claim the meter is rated for.

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Offline Tjita1

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UNI-T UT33A looks the same as the UT33C described in the list.
 

Offline wertyq

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I don't think there is any way to tell what needs to be changed without torture tests
 

Offline g0uli

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Just purchased a Uni-T UT71C from a supplier in Germany. The internal construction is pretty much the same as every other Uni-T meter with the exception that two correctly rated ceramic HRC fuses are fitted and the board is screen printed with '1000v fuse' on the side. The Cat ratings on the front have been downgraded to Cat 3 600v and Cat 2 1000v, which looks about right, given the circuit layout. The leads supplied have a 2000v Cat 3 rating printed along their length and shrouded probes. As a professional electrician, I wouldn't have any issues using this meter on UK 240 volt domestic mains so long as it is firmly restricted to protected circuits on the output side of the fuse/circuit breaker box. Overall the construction seems adequate to contain any problems inside the meter casing so long as it is used within its design limits. Overall a decent 5 digit 40,000 count meter for not a lot of money and obviously built to a better standard for the German market.

I bought this meter primarily for low voltage hobby purposes and the USB data logging ability. I have a proper calibrated Cat 4 meter for professional use.
 

Offline meeder

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http://www.elro.eu/en/products/cat/electronics/installation-material/meters1/universal-multimeter

Elro M970 multimeter. Lists CAT II 600V on it but only has 250V fuses.

Any guess on which manufacturer is making this thing?

User manual: http://www.elro.eu/uploads/products/manual/M970_Manual.pdf
 

Offline Lightages

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That is a Mastech.
 

Online tautech

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While joeqsmith's handheld DMM surge tests are not in a certified lab, should they not be linked to from this thread?
http://www.eevblog.com/forum/testgear/hear-kitty-kitty-kitty-nope-not-that-kind-of-cat/
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Offline Lightages

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While I agree that joeqsmith's tests are very interesting and teach quite a bit, I am not sure that they actually relate to multimeter safety standards. hey certainly show how certain multimeters can fail to operate after such testing and that should be a consideration when buying a multimeter. I am in the process revising the first post of this thread and probably will include a link to his videos and his thread but I want to clarify the requirements of the IEC about whether the meters need to survive completely or just not present a hazard to the user. This is still the big question.
 

Offline Wytnucls

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From Fluke's notes:
The International Electrotechnical Commission (IEC) established safety standards for working on electrical systems. Make sure you
are using a meter that meets the IEC category and voltage rating approved for the environment where the measurement is to be
made. For instance, if a voltage measurement needs to be made in an electrical panel with 480 V, then a meter rated Category
III 600 V or 1000 V should be used. This means the input circuitry of the meter has been designed to withstand voltage
transients commonly found in this environment without harming the user.

Also:
Special DMM overload protection prevents damage to both the meter and the circuit, while protecting the user.
« Last Edit: July 04, 2015, 08:45:58 pm by Wytnucls »
 

Offline jimdeane

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I have liked Extech products since buying a thermal IR thermometer from them years ago. I saw Dave J recommended it, so I bought it and an mn35 as a second/travel meter.

Dave J didn't seem to make a fuss about the fuse rating in the video. Did he not think it was a concern?
 

Offline steve207a

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Hi
many modern multimeters suffer from the modern age of shrinking everything down using the smallest case and components which in itself means isolation and protection suffer. Often the test leads are flimsy the wire gauge is suspect. fused test leads seem to be not an option nowadays . Old equipment was larger and bulky did not carry any CE mark or extra safety standard it was just built well to do the job .It did ohms volts and amps and that was that. nowadays they do cap testing, frequency, transistor testing ect seems the basic meter part is forgotten.when buying a test meter  some common sense is required to match it to the job inhand forget CE marks ect use your own eyes and common sense and dont put a thin  scrawny meter on anything over 12volts CE marked or not HA HA BOOM!!
 

Offline allikat

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Uni-T UT58 series (various models are delineated by screen print changes and new switch board). CatII/Cat III rated  :palm: , with 1kV range DC, 750V range AC. One small 250V rated 0.5A glass "Fast blow" fuse on mA range, 10A range unfused. :-DD

Bets on how quick a newb can let the magic smoke out?

PS: This forum really needs an escaping magic smoke smiley.
« Last Edit: December 06, 2015, 07:49:41 pm by allikat »
Any engineer can readily identify 3 smells:
1: Coffee, 2: Escaped magic smoke, 3: Bullshit
(from an original post by John Coloccia)
 

Offline allikat

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The version sold in Europe has been upgraded to meet the latest requirements. The PCB has been revised and it has the 1000V HRC fuses. Previous versions are now illegal, unless part of old stock imported before the deadline.

Plenty of old stock floating around Europe sadly. Maplins in the Bristol area did not have any stock with HRC fuses. Started with a UNI-T 58A, swapped it for a 60E as I had need of a meter urgently. Nearly said upgraded - lol. There seems to be space on the board, and contacts available to swap the 10A fuse to something more sensible. When I've got a workable soldering iron, I'll pick up a surface mount UK style fuse carrier and swap it in. It won't be full HRC but it'll be a ceramic fuse at least, and better than the pissant glass thing.
Any engineer can readily identify 3 smells:
1: Coffee, 2: Escaped magic smoke, 3: Bullshit
(from an original post by John Coloccia)
 

Offline crispy_tofu

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PS: This forum really needs an escaping magic smoke smiley.
:-BROKE close enough? :)
 

Offline allikat

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PS: This forum really needs an escaping magic smoke smiley.
:-BROKE close enough? :)
Pretty close.
Any engineer can readily identify 3 smells:
1: Coffee, 2: Escaped magic smoke, 3: Bullshit
(from an original post by John Coloccia)
 

Offline ChunkyPastaSauce

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Velleman DVM1090DMM (PCB inside says MASTECH MS8201H)
Marked with 1000V CATIII, 600V CATII, Fuses are rated at 250V (also the ceramic factory installed fuse appears to me as a slow blow, rather than the specified fast blow). I think insufficient track spacing for creep even at 600V, let alone 1000V. Poor soldering all around with many blobby soldering (the current shun was totally missed on the backside!). Improper strain relief on probes. Can't see much on input protection, nothing too fantastic I think.
http://i.imgur.com/RmTdS9V.jpg
http://i.imgur.com/N5NeeU6.jpg
http://i.imgur.com/OEDiTah.jpg
http://i.imgur.com/JwPOe5H.jpg

« Last Edit: March 19, 2016, 01:59:07 am by ChunkyPastaSauce »
 

Offline Hydrawerk

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Amazing machines. http://www.youtube.com/user/denha (It is not me...)
 

Offline System Error Message

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This is a very helpful thread. I have a VC99 multimeter and according to this thread i should open it and move things further apart inside? Also saying its not rated for mains voltage but it will do fine for your everyday 5V and 12V? If i just replace a fuse would it than be safe to use it for mains voltage?

So whats the danger with getting one of these multimeters and using them on your everyday small electronics like arduinos?
 

Offline Simon

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This is a very helpful thread. I have a VC99 multimeter and according to this thread i should open it and move things further apart inside? Also saying its not rated for mains voltage but it will do fine for your everyday 5V and 12V? If i just replace a fuse would it than be safe to use it for mains voltage?

So whats the danger with getting one of these multimeters and using them on your everyday small electronics like arduinos?

Avoid this meter, it's awful. An amprobe at the same price will werve you better.
https://www.simonselectronics.co.uk/shop New stock now in of EEVblog Brymen 235 and uCurrent Gold, Now selling a selection of Probe Master probes
 

Offline System Error Message

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even amprobe is on this list and extech, both meters which people recommend. How on earth do we get a meter when they're all on this list?
 

Offline PedroDaGr8

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even amprobe is on this list and extech, both meters which people recommend. How on earth do we get a meter when they're all on this list?

By doing their homework. Every company has dud models (even Fluke has had a few).

Amprobe has two models which are duds and loads of models that are safe and reliable. Even then, the two duds might have been updated or EOL'd I am not sure.

Very few ppl recommend Extech anymore, their QC is quite bad and getting worse. You just have too see Joe Smith's comparison of new versus old Extech.
The very existence of flamethrowers proves that some time, somewhere, someone said to themselves, "You know, I want to set those people over there on fire, but I'm just not close enough to get the job done." -George Carlin
 

Online joeqsmith

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What products does Fluke currently offer that you consider duds and why?
   
By doing their homework. Every company has dud models (even Fluke has had a few).

Amprobe has two models which are duds and loads of models that are safe and reliable. Even then, the two duds might have been updated or EOL'd I am not sure.

Very few ppl recommend Extech anymore, their QC is quite bad and getting worse. You just have too see Joe Smith's comparison of new versus old Extech.
How electrically robust is your meter?? http://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 


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