Products > Test Equipment
Multimeters that do not appear to meet their safety specs.
Lightages:
Revised: September 27 2013 18h10 UT
It is my intention here to start listing multimeters that appear to have designs or implementations that do match the intent of their rated CAT levels.
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.
A list of mulitmeters that appear to be properly designed and can be recommended is here:
https://www.eevblog.com/forum/product-reviews-photos-and-discussion/a-list-of-recommended-multimeters/
Please post the manufacturer, model, CAT ratings, fuse type and voltage, any images that support a suspected failing in meeting the specifications of the CAT rating, or ANY other information that causes suspicion that the CAT rating is not being met.
The criteria, in part, for these variations from meeting the ratings can be gleaned from here:
https://www.eevblog.com/forum/projects-designs-and-technical-stuff/cat-ratings-and-interpretation/
The main criteria is that all inputs must be able to withstand the maximum CAT ratings in all modes of operation, connected incorrectly or not, without harming the user. Current measurement protection must meet the CAT voltage rating as well, in other words fuses used must be rated for the maximum CAT rating on the meter.
If you have a meter that claims it is UL listed, you can search to see if it actually by searching for its certification here: http://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/index.html (thanks to grenet for the link). Each UL listed item will have a UL sticker on the piece of equipment. If you do not find this sticker then you probably have a fake UL listing on the equipment and it is not to be trusted until the listing can be verified using the link previously mentioned. A UL rating is no guarantee that the manufacturer continues to make the meter with any level of quality or the same way. Different countries also have their own standards. If a meter has a UL listing it does not guarantee that the meter actually meets its current CAT ratings claim according to the most recent CAT rating rules. For example the Extech EX330 is UL listed but does not meet the most recent rules for its claimed CAT rating.
Fluke do not recommended using the CE mark as a guide:
http://support.fluke.com/educators/Download/Asset/2096653_6003_ENG_D_W.PDF
They suggest UL, CSA, or TUV independent test markings. (as per Dave's post)
Yes, I asked Dave if this was a good idea and he said he had no objections to this.
It seems to me that listing meters with flaws is easier than proving compliance. Anyone can demonstrate a problem, almost no one here can prove compliance.
This list can never be comprehensive because there are so many junk meters on the market that it is impossible to list them all. Please use the information here to assist in assessing a meter for use on any high energy circuit even if you do not open the meter and provide a new submission. Generally one should never rely on the markings on a meter to truly reflect its safety.
Some people have been modifying fuse holders and adding over voltage protection components to their meters in an attempt to improve the safety of the meter. Adding better fuses is probably never a bad idea but adding over voltage protection components might not be a good idea. It is possible that the over voltage devices were omitted to achieve safety and not to avoid cost. Perhaps an MOV exploded during testing but when the meter was tested without the MOV the meter passed the test.
Just because a meter is not listed here does not imply it is safe or that it meets its CAT rating, it just means it is not listed. Many brands are just "rebranding" of other meters. Uni-Trend meters are also sold as Tenma, Voltcraft, and other brands for example
The list:
Uni-Trend UT71E (all A,B,C,D,E) CatIII/1000V CATIV/600V glass fuses used on current ranges with rating of 250V, battery lead with 600V insulated wires touching unprotected circuit board trace for Volts/Ohms input, might be an issue, might not. No indication on face of meter of low voltage fuses. (submitted by lightages)
Uni-Trend UT61E (all A,B,C,D,E) CATIII/1000V CATIV/600V ceramic fuses rated at 250V used on current ranges with 250V voltage warning on meter. Be aware that the UT61E has a different version available in Europe. It did not pass the labelled CATIV/600V CATIII/1000V ratings. The revised version is now rated at CATII/600V and CATIII/300V and has upgraded fuses and more input protection. The safety of this meter is a complete unknown now (submitted by lightages)
Victor VC9806+ CATIII/1000V glass fuses used on current ranges with rating of 250V, battery within clearance allowance for 1000V from fuses, no indication on current inputs of voltage limitations. (submitted by lightages)
Uni-Trend UT33C CATI/600V CATII/300V 10A range unfused, MA range glass fused with rating of 250V with warning of maximum 500V to be applied on the common volt/ohm/ma current inputs. (submitted by lightages)
Vichy VC99 CATII/1000V Current ranges use glass fuses rated at 250v with no warning of lower voltage, insufficient creepage distance from fuses to other parts, battery wire with unrated insulation passing through circuit board in contact with high current range circuit trace before fuse. (Submitted by T4P and review by electronupdate)
Minipa ET-997 CATII/1000V 20A range has glass fuse rated for 250V with no warning of lower voltage. (Submitted by T4P, teardown by metalphreak)
Mastech MS8218 CATIII/1000V Current ranges have ceramic fuses rated for 500V with no warning of lower voltage (Submitted by T4P, review by mjlorton)
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.
Elenco M-2625 also Jaycar Digitech QM1535 CATII/600V? MA current range has glass fuse rated for 250V with no warning of lower voltage. (Submitted by T4P, reviewed by Dave Jones)
Global Specialties Pro-50 CAT?, stated 1000VDC/700VAC MAX, 10A range not fused, MA range has glass fuse rated for 250V with no warning of lower voltage. Technically this meter appears to not be CAT rated so no implied safety rating(Submitted by T4P, reviewed by Dave Jones)
UNI-T UT90A CATII/1000V CATIII/600V ceramic fuses rated at 250V used on current ranges with 250V voltage warning on meter. 3 PTCs for input protection (Submitted by T4P)
UNI-T UT90C CATII/1000V CATIII/600V GLASS fuses rated at 250V used on current ranges with 250V voltage warning on meter. Some diodes to protect mA range? and 3 PTCs for input protection (Submitted by T4P)
Ideal 61-342 CATIII/600V Ceramic fuse used on MA range rated for 500V with no warning of lower voltage fuse. Technically this is a non-compliance to standards but a minor and probably inconsequential one. (Submitted by Lightages, reviewed by Dave Jones)
BK Precision 2709B/2712 CATIII/600V CATII/1000V Ceramic fuses used on both current ranges rated at 500V with no warning on meter. (Submitted by Lightages, reviewed by Dave Jones and 2712 by carloscuev)
Any Meter with the model number "830" All of these low priced meters are junk just waiting to blow up in your hand. (Submitted by Lightages)
Uni-Trend UT120C CATII/600V Self recovery 250V 400mA fuse over current protector on milliamps range. Reviewed by Wytnucls here https://www.eevblog.com/forum/reviews/uni-t-ut120c-review-and-tear-down/ (Submitted by Lightages)
Brymen BM867 CATIV/1000V Fuses rated only for 600V which is strange because the bigger brother BM869 which is built the same way has 1000V fuses. It appears that this problem can be corrected merely by installing the higher rated fuses. Reviews by mjlorton on his website www.mjlorton.com and here by iloveelectronics https://www.eevblog.com/forum/reviews/brymen-bm-867-teardown-pictures/ (Submitted by Lightages)
Amprobe AM-140-A CATIV/600V CATIII/1000V for voltage and lower rated for current. Fuses rated only for 600V which is strange because the bigger brother AM-160-A which is built the same way has 1000V fuses. It does state in the specs that the current range has a lower rating but it is not permitted to do so in the current CAT ratings standards. It appears that this problem can be corrected merely by installing the higher rated fuses. Review by jwrtiger https://www.eevblog.com/forum/reviews/amprobe-am-140-a/msg155623/#msg155623 (Submitted by Lightages)
UEi DM5B No CAT rating but claimed 500V safety while using fuses of 250V. (Submitted by Wytnucls)
Mastercraft sold by Canadian Tire A company named Canadian Tire in Canada rebrands and sells many different multimeters over the years and almost all of them do not come close to meeting any safety standard. (Submitted by 2dfx)
Amrpobe AM-220/240 CATIII/600V with fuses rated only for 250V with warning of lower rating on meter. This made worse by the fact that the order of the input jacks have been changed which could lead to errors in use, and that the MA range shares a common jack with the V/ohms range.(Submitted by ivan747)
Digitek DT-2843R CATIII/600V with fuses rated only for 250V with warning of lower rating on meter. Reviewed by Lightages here: https://www.eevblog.com/forum/testgear/review-digitek-dt-2843r-trms-for-less/ (Submitted by Lightages)
Digitek DT-4000ZC / TekPower TP4000ZC CATIII/600V with fuses rated only for 250V with warning of lower rating on meter. Reviewed by mjlorton.com (Submitted by Lightages)
Elenco M-2666K Rated 1000V (No CAT rating implied) with fuse rated only for 250V with no warning of lower rating on meter, 20A range unfused. (Submitted by rexxar)
Mastech MS8229 / Protek 6300 CATIII/600V CATII/1000V with fuses rated only for 500V with no warning of lower rating on meter. (Submitted by madsci)
alm:
Wouldn't it be more efficient to list all of the instruments that do conform to safety standards? Since the CE mark requires conformity to EN61010 for multimeters, I would expect essentially any cheap multimeter and probably many of the < $100 meters sold in the EU to be in violation unless explicitly limited to SELV. Just the lack of over voltage category markings would be a violation, not to mention the fact that they may not even conform to CAT I.
Astroplio:
Not a bad idea for this thread, but shouldn't we also consider the quality/safety of their probes?
And if yes, then how can we comment on that? It looks to me it is hard to tell, but I personally would never touch mains voltage with a cheap multimeter's leads, just battery powered circuits.
Also it would be cool if people could advise for improvements of listed instruments here, i.e. a HRC fuse replacement could be all that is needed in some of these DMMs.
Thanks
George
alm:
I don't think there is any way to tell what needs to be changed without torture tests. If they skimped on the fuses, they may as well skimped on other critical areas like clearance, quality of components and enclosure. Just replacing one critical component may not be enough. It's much easier to determine if something definitely does not meet spec (glass fuse, insufficient clearance) than it is to guarantee that something will pass the relevant tests.
Wytnucls:
--- Quote from: alm on October 27, 2012, 01:02:27 pm ---Wouldn't it be more efficient to list all of the instruments that do conform to safety standards? Since the CE mark requires conformity to EN61010 for multimeters, I would expect essentially any cheap multimeter and probably many of the < $100 meters sold in the EU to be in violation unless explicitly limited to SELV. Just the lack of over voltage category markings would be a violation, not to mention the fact that they may not even conform to CAT I.
--- End quote ---
I agree that it would be more efficient to list the meters that qualify, as that club is far smaller, in my view.
Also, remember that these regulations changed recently and we don't know what the specifications were previously.
Navigation
[0] Message Index
[#] Next page
Go to full version