Author Topic: Multimeters that do not appear to meet their safety specs. (updated frequently)  (Read 143410 times)

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Offline G7PSK

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I couldn't agree more. In (semi) industrial environments the circumstances are totally different. High voltage outlets, dangerous chemicals, etc. Over here it is mandatory to have a safety license before you can work in such environments. And still you may not get into every factory. Many years ago I had to work in a chemical factory. The least toxic stuff they had in there was Chlorine. Before anyone was allowed on the premises they had to take a safety course (covering handling toxic chemical spills, entering rooms, locking out parts of the plant, etc) and an exam. After taking the exam succesfully (score >90%) you'd get a safety passport which was valid for one year.

I once had to do some work at the DOW chemical factory in Kings Lynn Norfolk UK, this involved some welding for which I had to submit a safety sheet, on the sheet I stated that a portable welding generator was to be used, I got the contract letter back authorizing the welding with the condition that the power unit was diesel due to the concerns that a petrol powered welder may produce sparks from the engine. I don't know what they thought happened at the other end of the lead.
 

Online nctnico

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Safety wise it makes perfect sense to me. Most safety rules are based on lessons learned in the past. Where do you look at during welding? At the welding or the power unit? IOW: when something goes wrong what is noticed first and what is probably not noticed at all?
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline G7PSK

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They were worried about sparks igniting things the welding power unit is outside in the ope due to exhaust gases meanwhile the operator is inside the building full of combustible liquids up in the rafters welding brackets for an overhead gantry, showering sparks over everything with only a glass fiber blanket covering and they are worried about a spark from the ignition system and I have known diesel engines throw sparks out of the exhaust.
 

Offline Ba1tuks

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The interesting thing in my experience is that cheap(not ridiculously cheap), 50-150 dollar meter isn't that dangerous as all of you speak. Ok, it blows inside, but if case is sturdy enough - nothing will ever happen to you. So stop that "if you wan't to live" crap :-) In 12 years I fried only one DMM, cheap, 40 buck one, when my HV PSU gone wacky and full 2KV 0,5A power to the output, and DMM was hooked up to it for more precise voltage setting. I have better DMM, agilent U1242B, very happy with it, but the death of cheap DMM only amused me :-D while the death of agilent would have knocked me on my knees screaming "why gog, why!?", pounding my head into the bench :-D
Yes, money has much bigger value  for me now :-) Studying at university, zero parent support...
 

Offline Lightages

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I am glad you have never had a problem with a multimeter causing you harm. Most people, the majority, will never experience anything near dangerous happening with anything they do. This does not mean it does not happen. It just means it does not happen to almost everyone. There are real reasons why safety standards exist. That is because something has happened at least once to cause people to look at preventing it from happening again.

I personally have seen a number of electricians walking around with burn scarred faces, missing fingers, and skin grafts. Yes that is an electrician and not a hobbiest. Electronics hobbiests are not likely to encounter the same conditions as an electrician. That does not mean that some hobbiest won't take his $5 meter and start troubleshooting his house wiring when he has a problem.

The main thing is to be familiar with the potential problems and the capacity of your equipment to deal with problems and errors. That is where this list is to be used, to gain knowledge. If a piece of equipment is rated to be safe for something and it really isn't, I think it is better to know an be able to assess your risk. I really doubt anyone here will argue that not knowing is better.

If you are paying for something, I also think it is better to know if you are getting what you think you are paying for. And if a company is willing to be outright dishonest about a safety rating, it is also highly unlikely that you get the other specifications you think you are paying for.
« Last Edit: March 26, 2013, 07:12:56 am by Lightages »
 

Offline ConKbot

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The interesting thing in my experience is that cheap(not ridiculously cheap), 50-150 dollar meter isn't that dangerous as all of you speak. Ok, it blows inside, but if case is sturdy enough - nothing will ever happen to you. So stop that "if you wan't to live" crap :-) In 12 years I fried only one DMM, cheap, 40 buck one, when my HV PSU gone wacky and full 2KV 0,5A power to the output, and DMM was hooked up to it for more precise voltage setting. I have better DMM, agilent U1242B, very happy with it, but the death of cheap DMM only amused me :-D while the death of agilent would have knocked me on my knees screaming "why gog, why!?", pounding my head into the bench :-D
Yes, money has much bigger value  for me now :-) Studying at university, zero parent support...

1KW power supply is much different than working in a breaker panel.   Not everyone needs a cat III/IV meter,  so evaluate your needs, and buy something that suits them  If your meter is going to stay on your bench or in your car, and the only fault with the meter is no HRC fuse and no blast shields around the fuse/sockets,  and it meets all your other needs and price point, sure, get it, enjoy your savings. 

While 240V wont arc-flash like like 480v, if youre probing in something like a panel and you get a transient that makes your chinese meter arc the 2mm between the input traces and it establishes an arc of vaporized copper and burnt paper-epoxy PBC, while the meter is in your hand...  you may be needing new pants at best.   

Full disclosure is better than people being lied to and injuring themselves, its not a matter of "dont buy these meters" so much as "dont buy these and use them somewhere where you will need CATIII/IV"   Though I'd prefer not to buy something where the manufacturer is lying about its capabilities, but thats up to each consumer.
 

Offline Lightages

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Full disclosure is better than people being lied to and injuring themselves, its not a matter of "dont buy these meters" so much as "dont buy these and use them somewhere where you will need CATIII/IV"   Though I'd prefer not to buy something where the manufacturer is lying about its capabilities, but thats up to each consumer.

Exactly. That is what I state in the first post:
Quote
The intent of this thread is to provide at least a partial list of multimeters that are to be assessed on their physical and feature merits rather than to rely on their stated CAT ratings for assumption of safety. I will update this post each time I see a new post with a new multimeter so as to keep the list in one spot. I hope to save someone grief or injury by compiling this information."
 

Offline Wytnucls

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UEI DM5B
500mA and 5A 250V fuses
Max voltage 750V AC&DC
 

Offline ConKbot

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UEI DM5B
500mA and 5A 250V fuses
Max voltage 750V AC&DC

750V auto ranging, but only "500V protected"  and 250V fuses.   Marketing genius.

"ehh its good for 500, but you can probably get upto 750 without dying"
 

Offline c4757p

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That kind of "it's possible, but it's not really" seems unfortunately common in the industry. I was just sifting through specs for ITEAD's PCB service and they say they do 6mil traces "8mil recommended" (i.e., "8mil traces, but if you give us 6mil we'll shove it through the DRC anyway").  |O
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Offline Spawn

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UEI DM5B
500mA and 5A 250V fuses
Max voltage 750V AC&DC

That’s why I am trying to get one for a decent price, the shipment cost spoils it. Above all those statements it has only two lead inputs so far I could see on different images, so you are testing current till 5 amps and voltage till 500V at same inputs.

I can understand all this fuzz about protection since the companies claim to have it so they should, but how many of you did measure anything higher than 400V in CATIII environment?
I sure didn’t after 23 years as a Electrics field engineer, I am asking this because most people here are Electronics hobbyists, so do you really need anything which can measure higher than 400V protected and how many of those guys/girls have the education to do so? It is not only the meter you work with but the way you work is also important in those environments.

Offline Lightages

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how many of you did measure anything higher than 400V in CATIII environment?
I sure didn’t after 23 years as a Electrics field engineer, I am asking this because most people here are Electronics hobbyists, so do you really need anything which can measure higher than 400V protected and how many of those guys/girls have the education to do so? It is not only the meter you work with but the way you work is also important in those environments.

Full agreement from me. As I said, the information is presented as just that, information. Probably 99.99% of the people here do not connect to these conditions. Someone might, and while believing the rating on the meter. Information is never a bad thing. And again I say.... If the manufacturer is lying about one thing it is very lkely they are lying about other specs too.

And FYI, I deal with 600VDC 10A circuits that can climb to over 1000V if not connected right. I think I want to be sure I have the right meter for the job. If not to protect me, at least to make sure my meter doesn't die while using it in this situation. Many meters I have seen would be outright dangerous to themselves or to me. What if the meter partially fails and shows no voltage and then I use that as a sign that it is safe for me to touch those wires? The safety of a meter affects many things.
 

Offline Spawn

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Of course documenting these is good thing to do Lightages, nothing against that :)

I am referring to recommendations in other topics when a hobbyist ask what Multimeter to get, you, me and other handful  professional  members know what meter to get when it comes to work with high voltages. Our equipment at work gets yearly inspected.
A hobbyist could do perfect with a Uni-T for example, still good build and accurate in “most” cases. If you ask me, a hobbyist shouldn’t even get near open rail systems and there won’t be any issues with most of those meters. If we have to work in those environments we need to dress up like we walk on the moon, let alone using a meter with suspicious protection.

I won’t lie, I was looking for a cheaper alternative at work for the field technicians working for me, but as you know with Extech experience I got the search was finished right where it started. We will keep using Flukes. Alternatives like Amprobe, Agilent and Gossen Metrawatt won’t save that much financially and since I have good experience with Flukes when it comes to sturdiness we decided to keep working with Flukes, Amprobe could be little cheaper but I am not sure how long it will survive in Electricians toolbox.

Offline Lightages

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Again we have an agreement. Most people here will never play with high energy. A UT61E will be fine for almost anybody on this forum. The TekPower TP4000ZC / Digitek DT-4000ZC that Frankie sells will be all that some need. Both are under $60. As far as the safety thing goes, I don't think we are necessarily overstating it because the reader at least now knows the difference and can now make a judgment based on this rather than blindly trusting the CAT rating a meter claims to have.

BTW, I think you should give the BM257 a look for the cheaper alternative for the Flukes. Maybe just wait till Dave finally gets around to the shootout.
« Last Edit: March 28, 2013, 10:17:37 am by Lightages »
 

Offline Spawn

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It is to late, he has a Fluke 77-4 now. Maybe next guy who "loose" his DMM will get another one. 

Offline 2dfx

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Was wondering if I could chime in here with an investigation here of my own.  Here in Canada, one company here called Canadian Tire sells DMM's under their Mastercraft name.  I have a model here  52-0055-6 which is CATII rated, 1000V DC 750V AC.  The fuses as you will see do not comply with this metric as it has 500mA & 10A 250V fuses.


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« Last Edit: April 01, 2013, 09:17:27 am by 2dfx »
 

Offline ResR

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Elix M266. 750VAC 1000VDC rated and no fuse :scared: only pair of resistors :palm: . How it got IEC1010 approval anyway, I wonder._
 

Offline ivan747

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Lightages, please see this thread about the AM-220 ceramic fuses -they are not HRC.

http://www.eevblog.com/forum/testgear/amprobe-caught-using-fake-hrc-fuses/
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Offline Lightages

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Elix M266. 750VAC 1000VDC rated and no fuse :scared: only pair of resistors :palm: . How it got IEC1010 approval anyway, I wonder._

Sorry I didn't get back to this before. Actually, that meter might pass its CAT rating. It has no current testing using the the test leads so it does not need fuses. I really doubt it meets its CAT rating but it is not obvious. This is just another copy/rebrand of the very badly made generic "266" clamp meters. See:
http://www.eevblog.com/forum/testgear/mini-review-teardown-generic-dt-266f-clamp-meter-aka-pos/

So I cannot actually include this in this list but I agree this POS should be avoided.
 

Offline Lightages

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Lightages, please see this thread about the AM-220 ceramic fuses -they are not HRC.

Well they not be HRC, but as already said they are not specified as such. No matter, that meter is not properly rated and so it goes on the list. I particularly hate the common current/voltage input jack as this is an accident waiting to happen. The reversed order of the jacks is also another disaster waiting in the wings.
 

Offline maiakaat

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Extech perhaps don't deserve to be given such a critical assessment.

I have an EX510 with what looks like a revision 2 board, and better use of space around the probe terminals, with no possibility for any component to short.

The Fuses are both 1000V SIBA HRC

One of the fuse mounts for the 0.8 Amp fuse looks soldered on the wrong way around, so they probably should really get rid of the factory they are using to resolve the remaining issues as it seems clear this is where the problem lies (and they may have done that by now as this is probably at least a few years old I would guess as it was old new stock I got cheap (under $50)

It was also able to forward bios a white LED

They really should use a better selector on the front though.
 

Offline Lightages

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maiakaat

Perhaps Extech might be trying to improve things. Technically many of their meters might meet their CAT ratings as does the EX510 in your post. I have listed the actual meters that I have reports of that don't but have made a sweeping statement n the rest because of all the reports of really bad quality control. Yours looks good but it has a fuse holder mounted backwards? That is still totally unacceptable and I think Extech needs to prove they have fixed things and people will not encounter anymore ridiculous issues before I will ever look at one again in the EX series. And really, you present one more example of an EX series that is made wrong instead of providing an example where nothing is wrong and say we should give Extech a break?
 

Offline maiakaat

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Agreed, they do seem to be trying though, it would be interesting to see how their newest, most recently made products look.
 

Offline M0BSW

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I wonder how my old Fluke 75 would measure up to the  laws these days out of curiosity that is
 

Offline Lightages

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Well it is easy to see if it meets the labeling and component requisites. It does not say "CATX/XXXV" so it does not meet a technical spec. The fuses are not rated for the 1000V it has labeled on the front, so again not correctly built to latest standards. The rest looks good and it probably is better better protected than many other meters today. I would bet if you replaced the fuses with properly rated ones that it would pass the latest CAT ratings test for at least CATIII/600V.
 


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