Do cheap meters explode when you abuse them? - Page 1
Forum section: electronics / testgear

author: paulie
author_rank: Frequent Contributor
timestamp: May 28, 2015, 07:15:47 pm
content: Apparently not. At least not in my initial crude non-scientific tests (see pics below). BTW this is a continuation of the discussion in another thread which was totally hijacked starting on second page:https://www.eevblog.com/forum/testgear/the-uni-t-ut33c-or-d-how-good-they-are/15/First abuse involved applying to a car type battery while set up for ohms measurment. No detectable damage. Meter still works fine in all ranges. Then tried it in milliamp range. This time meter stopped working. Later verified fuse was blown which is to be expected.Next came shorting directly across the battery with probes plugged into 10a jacks. Range settings do not matter under these conditions because probes are essentially connected only to the shunt which is really a dead short. No bright flash, explosion, or shrapnel. What did happen was NOTHING at first. Even pressing hard to ensure good contact.I put the camera down and checked battery voltage with another meter in parallel (set to measure VOLTAGE!). It drops from 14.3v to a little over 14.1v indicating considerable current drain but holding up well. For about the first 20 seconds no indication anything was amiss except probe handles heating up. I'm sure the cables themselves were getting real hot but holding probes and camera not enough hands to check.Then the cables started squirming and a few seconds later hints of smoke. This went on for about another half minute after which the smoking got serious. At about a minute and a half the smoking decreased until after another minute no hint of smoke or heat. I assumed at this point one of the leads had opened and verified using the same meter with new fuse and another set of probes. See photo below of the obvious damage.I also experimented with applying lines voltage in a variety of incorrect settings. results were pretty much the same as smjcuk in that other thread:Quote from: smjcuk on May 28, 2015, 12:23:13 pmWe are talking dead short across 240vac, serious abuse. Blown fuse but no damage to meter or probes.So being much braver than him (and meter that did not cost even one penny) I decided to see what happens there but with probes plugged into the 10a jacks. Unlike with the battery there WAS a bright flash this time but no damage to the meter or leads because the six outlet strip breaker tripped. Reset breaker and one more time same thing, flash and nothing except some pitting on probes.I do believe the videos of exploding meters are real and have no doubt top end products like Fluke are much safer under those conditions. However we're talking kilovolt potentials with nearly unlimited current. That bank took up half the room. Strictly a scientific curiosity. Nothing anyone using one of these cheap meters would conceivably encounter.No doubt playing around with mains is dangerous and unless you know what you are doing make no attempt. Grabbing the wrong wires or careless handling of a tool can be fatal. However IMO the fear mongers go a bit overboard with warning to never use cheap meters for anything except low voltage and low current. I'm convinced ratings manufacturers put on these are reasonable and personally would not hesitate to use them as designed. Certainly in the case of Harbor Freight or Uni-T products. Like any tool though misuse can have tragic consequences so be careful and make sure you know what you are doing.update: I did some kilovolt testing of the above meter but joeqsmith did a much better job on a similar Harbor Freight cheapie so I hope he don't linking it here:Not as entertaining as ones posted in this thread from Dave, Fungus, the Fluke guy, and others but unbiased objective reviews do have a place too. Probably most out there, by taking note of demeanor and body language, can judge for themselves where these fit in that respect.

author: SeanB
author_rank: Super Contributor
timestamp: May 28, 2015, 07:24:57 pm
content: See Martin's video of his visit to Fluke.http://mjlorton.com/forum/index.php?topic=821.0There you see that meter being tested to the marked standard, inside a cabinet. Then a well used Fluke meter is plugged in for the same test, and this time the meter is out of the cabinet and is being held in the tester's hand.He also indicated that the supplied leads with the meters was always going to fail at high current, and that often they were faulty out of the box.

author: Muxr
author_rank: Super Contributor
timestamp: May 28, 2015, 07:31:40 pm
content: Isn't the lead damage you show in those pictures exactly what I warned about? You called me a fearmonger for pointing out something you actually reproduced on a first try? I remember your response being, "bah, it's alright PCB trace is a fuse!".Kids don't buy unfused meters, $38 saved isn't worth it over a properly fused meter.

author: Fungus
author_rank: Super Contributor
timestamp: May 28, 2015, 07:34:12 pm
content: The problem with giving out multimeter 'wisdom' in online forums is that people read it and repeat it.If you've never playedChinese Whispersthen maybe you should. It's astonishing. Even five or six people canutterlychange asimplemessage. You have to see it with your own eyes to believe it. It doesn't seem possible.A posting that says "I plugged my UT33C" into a car battery and nothing happened" will soon change into "Yeah, dude, I know this guy whototallyknows electronics and he says these $4 meters are fine and that all those people who pay $200 for meters are fools. Let's see how many Amps your house is using".The ONLY correct advice in online forums IMHO is to tell people to do things correctly. Don't poke multimeters into mains sockets.PS: Here's some more "data points" to peruse...CAT III meter nearly kills our host:Expensive CAT III meter kills two people:http://ecmweb.com/arc-flash/case-deadly-arc-flashEdit: Nope, it wasn't "CAT III", my feeble memory was mixing it up with another story about a dangerous meter.

author: Monkeh
author_rank: Super Contributor
timestamp: May 28, 2015, 07:37:55 pm
content: Quote from: Fungus on May 28, 2015, 07:34:12 pmErrr, no, if you read that, you'll find that not only was it never CAT rated, but that it was never even tested to full supposed operating voltage.The electrician probing a high energy circuit with an inappropriate tool and no PPE killed himself and the guy foolish enough to stand next to him.

author: paulie
author_rank: Frequent Contributor
timestamp: May 28, 2015, 07:44:21 pm
content: Quote from: Fungus on May 28, 2015, 07:34:12 pmWe absolutely agree on that. The previous thread and many others before that too are a clear example.

author: Fungus
author_rank: Super Contributor
timestamp: May 28, 2015, 07:45:37 pm
content: Quote from: Monkeh on May 28, 2015, 07:37:55 pmOh, memory failed me since last time I read it (which was in a thread about a dangerous meter with "CAT III" stamped on the front).How about we change it to: "A trained electrician plus bystanders were killed by a cheap-ass meter. Would still be alive if he'd used a $200 meter..."Happy now?

author: Fungus
author_rank: Super Contributor
timestamp: May 28, 2015, 08:03:12 pm
content: Quote from: paulie on May 28, 2015, 07:44:21 pmEvery forum has a variant of this thread.eg. In Arduino forums it's, "I connect LEDs to my Arduino without any resistors and they work perfectly! I do it every day!!"

author: Mr Simpleton
author_rank: Unknown
timestamp: May 28, 2015, 08:05:14 pm
content: Long time ago I had this quality meter, think it was a Metrawatt... problem was that the range selector was a round wheel and very easy to set in the wrong position. I ended up with mA range and put the test leads into a mains socket... Yes this was pretty close to what I would call an explosion! The shunt desintegrated and tried to penitrate the box in several places, I guess it not only tried by force but also melted the plastic...Now having done this I promtly borrowed a Simpson meter, and yes do not ask why but this was set into 10 A range and used in the same mains socket. This took out the wall fuse, but damage to the meter was minor.So I would say, considering my first hand experience: It depends!

author: Fungus
author_rank: Super Contributor
timestamp: May 28, 2015, 08:15:24 pm
content: One more datapoint (last one, I promise):A Fluke 101 with shipping can be had for less than $43, eg.http://www.ebay.com/itm/331068818894If you work with household mains and need to measure actual voltages then that's as much as you need to spend to be pretty damn safe.

author: Fungus
author_rank: Super Contributor
timestamp: May 28, 2015, 08:23:02 pm
content: Quote from: paulie on May 28, 2015, 07:15:47 pmHow close were you to the distribution panel? A few meters of wire between you and the panel can make abigdifference (it's the main difference between CAT II and CAT III ratings).

author: paulie
author_rank: Frequent Contributor
timestamp: May 28, 2015, 08:25:04 pm
content: Quote from: Fungus on May 28, 2015, 07:34:12 pmWe ALMOST agree on that. I would slightly modify as follows:"The ONLY correct advice in online forums IMHO is to tell people to do things correctly. Don't poke multimeters into mains sockets UNLESS YOU KNOW WHAT YOU ARE DOING."Certainly more deaths occur every year involving mains voltage and paper clip or hairpin. I am serious.Quote from: Fungus on May 28, 2015, 07:34:12 pmLOL. Thanks for that one. I love that guy. I've collected over a dozen of his dealing exclusively with "shit" meters and every one a gem. None of the others even hinted at "death by bang" though. Yours are up there too. In addition to the actually good advice I find specially amusing the way you guys cradle and coo over the "good" product and snarl and toss around the "bad" one.ps. I also got a kick out of the time over-voltage blew the dial right off the Fluke and across the room. After picking it up and popping it back in he said "Good as gold!" even though it was obviously trash. Or the time the Fluke was dropped from huge heights and finally broke from 100' or so. "No problem... just a broken display and dislocated inductor!". Priceless, or should I say "Un... Buh... Leeeevable !!!".

author: Fungus
author_rank: Super Contributor
timestamp: May 28, 2015, 08:37:53 pm
content: Quote from: paulie on May 28, 2015, 08:25:04 pmNot so fast: I dissed a Fluke 27 in my "Sparkfun" video.Took some flak over it, too.

author: paulie
author_rank: Frequent Contributor
timestamp: May 28, 2015, 08:47:50 pm
content: Quote from: Muxr on May 28, 2015, 07:31:40 pmI don't recall using that phrase, maybe something from somebody misquoting me in a moment of passion. But IIRC you were probably the first to bring up leads melted by car battery. And not so prone to exaggeration and excessive FUD as HW calls it. Not like some of these guys anyway.I do think it's great to bring up these points, even the hysterical extremes, as anything to promote care around high voltage and current can only be a good thing. If a noob spends a few buck more than necessary based on advice from an over excitable pundit, no big deal. Underestimating the dangers of electricity... different story.

author: paulie
author_rank: Frequent Contributor
timestamp: May 28, 2015, 08:58:06 pm
content: Quote from: Fungus on May 28, 2015, 08:37:53 pmYes, 99% of the time you guys provide sound and balanced advice. Hard to hide prejudice over cheapo product.BTW many comments in that review rang true. For example we both appreciate small compact packages. One reason I am partial to the cheapies is they are no so bug and clunky as "real" DMMs.ps. "big" not "bug"

author: Fungus
author_rank: Super Contributor
timestamp: May 28, 2015, 09:01:08 pm
content: Quote from: paulie on May 28, 2015, 08:25:04 pmDave's video says the multimeter exploded in his hand. I'm sure Dave knows what he's doing.Maybe we can agree on: "Don't poke multimeters into mains sockets UNLESS YOU KNOW WHAT YOU ARE DOINGandbought a Fluke."(Yes, thereareother brands out there apart from Fluke but this is 'general advice for Joe Public' and how many non EEVBLOG-readers would know where to buy a Brymen/Gossen/Agilent/whatever?)

author: c4757p
author_rank: Super Contributor
timestamp: May 28, 2015, 09:07:21 pm
content: Nothing wrong with inexpensive meters, but you're a chump and the seller a prick if you buy one that'sunfused. This very controlled experiment is not evidence against the need for fuses.

author: smjcuk
author_rank: Frequent Contributor
timestamp: May 28, 2015, 09:54:21 pm
content: Notes about my experiment:1. I didn't use the unfused 10A section of the UT33A. You'd have to be a fucktard to poke any meter in a 10A circuit or more even if Bono from U2 himself cast it from his own molten ego. That's what clamps are for. I wouldn't even trust my Fluke 77 with this.2. I'm a qualified EE so understand the safety consequences of this experiment and how to control and isolate the power safely.3. I'd be happy to use a UT33A for casual electrical work around the house and office i.e. AC voltage go/no go testing and earthing continuity/resistance as well as electronic work.4. I'm in the UK so we have real 240v *everywhere*, not just in some circuits.5. This applies to this UT33A and this revision of this UT33ATBH I was expecting it to explode. But it didn't.The important point is not "and buy a fluke" but "know what you are doing and check and double check before you do it".Now I know someone who just blew up a Megger MFT1730 on a 415V circuit so at £950 don't expect miracles either if you do something stupid.

author: Ian.M
author_rank: Super Contributor
timestamp: May 28, 2015, 10:29:07 pm
content: You are also a chump if you hold a cheap meter in your hand while probing a mains circuit. That violates the basic safety practice of keeping one hand in your pocket when probing circuits that exceed SELV voltages to avoid the risk of getting a shock across the chest.If you need to hold the meter in your hand while probing fused mains circuits, then you should get a professional quality, appropriately rated one with a rubber sleeve on it as that adds extra protection where you are most likely to be gripping it, which can only help if it fails catastrophically. If you are probing high current high voltage circuits, you should be using individually fused test leads as well.Dave should probably have been more cautious and initially tested the meter on his bench, not in his hand, but that was many many EEVblogs ago and I'd bet that after all the cheap multimeters he has seen since then, his sense of self-preservation is a lot more finely tuned now.

author: DanielS
author_rank: Frequent Contributor
timestamp: May 28, 2015, 10:52:33 pm
content: When I troubleshoot something that might literally blow up in my face, I plug the DUT into a switched power strip under my bench and use that to turn power on/off. This way, I'm ducking under my bench when applying power and if something has to go horribly wrong, it will usually be over before my finger is off the switch.

author: smjcuk
author_rank: Frequent Contributor
timestamp: May 28, 2015, 10:58:48 pm
content: I take it outside and put it in the porcelain bath that lives in my back garden on an industrial extension lead and an RCDQuote from: Ian.M on May 28, 2015, 10:29:07 pmDefinitely. This should be #1 rule. Always probe with one hand. Even on low voltage, low current circuits it stops probe slippage and accidental shorts that blow things up.Also safety glasses.

author: Lightages
author_rank: Unknown
timestamp: May 28, 2015, 11:39:21 pm
content: Do cheap meters explode when you abuse them?It depends on the abuse, and the situation. One test with unknown conditions does not make a definitive test, nor does it give a definitive result. The test showed some indications of danger but that was dismissed. I am not surprised.

author: nanofrog
author_rank: Super Contributor
timestamp: May 29, 2015, 12:18:45 am
content: Quote from: paulie on May 28, 2015, 08:25:04 pmThis is the heart of it IMHO.Bad habits picked up on low energy circuits can easily injure or even prove fatal on high energy circuits. And very easy to happen on a bench IMHO as most work isn't high energy (mistakes might blow stuff up, but not nearly the possibility of severe injury or death).Safety glasses are also recommended, but also often ignored on a bench. I spent many years without any kind of lenses between my eyes and meters & DUT's. Now I rely on my prescription eyewear as they're polycarbonate.Quote from: Ian.M on May 28, 2015, 10:29:07 pmThis is also where the magnetic holders come in handy IMHO (not saying a substitute for a good rubber holster/boot, but in addition as it further aids in promoting the "keep one hand-in-pocket" safety rule).

author: joeqsmith
author_rank: Super Contributor
timestamp: May 29, 2015, 02:44:06 am
content: Quote from: paulie on May 28, 2015, 07:15:47 pmI have been thinking about this as well . I was unable to find any details about 1010 and am curious just what they really do require. I have the 1010 standard coming.Seems like if you are going to do a review, and safety is part of what you want to talk about, you need to test them to this standard. Maybe test them to failure and see what sort of head room they have.

author: Fungus
author_rank: Super Contributor
timestamp: May 29, 2015, 08:53:54 am
content: I'm curious about why people would be arguing in favor of probing household mains circuits with multimeters.Under what circumstances do youneedto do that as opposed to just plugging in a lamp or using one of those volt sticks?I'm sure there must be some but I think it will be a very short list.

author: george graves
author_rank: Super Contributor
timestamp: May 29, 2015, 10:19:58 am
content: Quote from: SeanB on May 28, 2015, 07:24:57 pmIt is a good video to watch to learn about fluke testing - kinda - there's a lot of sales pitch thrown in - but they guy makes a great show of why flukes are safe to probe +300v. Mjlorton's videos are often full of flaws. (Like tons of them) He openly admits it in his show opening, that he's just mucking about. Take anything he says with a grain of salt.

author: paulie
author_rank: Frequent Contributor
timestamp: May 29, 2015, 02:32:10 pm
content: Quote from: Shock on May 29, 2015, 02:12:11 pmI probably will not follow your advice as suggestions like that are indication of a twisted personality. You do seem to be a perfect example of the type alluded to earlier so forgive me if I take your claim of seeing "a multimeter and leads blow up in person" with a grain of salt. "Shock" tactics don't work on me.Anyway there is more news on cheap meters vs protection. All the whining about having to spend a hundred bucks or even as little as fifty to save lives may be a bit misplaced in view of recent dissection of my $12 Uni-T meter (well, I took the back off) . Turns out to my surprise there IS a 10a fuse in addition to the milliamp one. And guess what? CERAMIC !!! I know some of us love those. Let's think up some other picayune trait for those with more money than brains to go on and on about.ps. I can put up some photos if there is interest.

author: Kleinstein
author_rank: Super Contributor
timestamp: May 29, 2015, 06:40:52 pm
content: For the Uni-T meters, there are several versions, that look very similar from the outside and have same label. So especially with a very cheap meter, unless you open it up, you don't know if you get the version for US, European (possibly OK) or the Chinese / Russian marked or even a countrified one thats even worse. So even if one meter survives a test this does not mean that model is safe. At best a failed test shows that this model is not safe.With mains voltage, the distance to the meter and transformer can make a big difference. I once saw what happens if distances are short (in this case very short - less than 5 m to the distribution transformer). A normal ligh bulb blew with an short - normaly just the fuse blows. However this time the 16 A (electromechanical) and 35 A (melt type) and 100 A fuse blew. The light bulb literally exploded with the glass partially covered with copper from the inside. The cable to the fuse cabinet and from fuse cabinet turned brown. Likely the 16 A fuse was not able to brake the current - though rated at something like 6 to 10 kA. So be extra careful if you have a low impedance output that might need CAT III rating.

author: Fungus
author_rank: Super Contributor
timestamp: May 29, 2015, 06:43:39 pm
content: Quote from: paulie on May 29, 2015, 02:32:10 pmSure. Inyours.PS: That statement should tell you something about yet another difference between Uni-T and Fluke.

author: SeanB
author_rank: Super Contributor
timestamp: May 29, 2015, 07:39:37 pm
content: You get fake ceramic fuses as well, I have had them explode in microwave ovens before, where they are supposed to blow without turning into shrapnel.

author: nanofrog
author_rank: Super Contributor
timestamp: May 29, 2015, 07:52:55 pm
content: Quote from: SeanB on May 29, 2015, 07:39:37 pmSadly, if there's a profit to be made as a result of producing counterfeits, someone will.

author: Lightages
author_rank: Unknown
timestamp: May 30, 2015, 12:16:05 am
content: Quote from: paulie on May 29, 2015, 02:32:10 pmHmmmmm, I wonder which is worse, being liberal with other people's money, or being liberal with other people's safety?It can be, and has been demonstrated that cheap meters have injured and killed people. I am sure you cannot demonstrate the opposite.And why are you insulting other people here instead of sticking to the subject? This is usually a sign that a person does not have valid points or real evidence to back their claims.

author: helius
author_rank: Super Contributor
timestamp: May 30, 2015, 12:39:27 am
content: ceramic fuses are not the highest safety rated kind of fuse. ceramic is a brittle material and will shatter with sufficient force. the HRC fuses are made from woven melamine for this reason.

author: johansen
author_rank: Super Contributor
timestamp: May 30, 2015, 01:20:14 am
content: Quote from: Ian.M on May 28, 2015, 10:29:07 pmmake sure to wear a face shield

author: John Coloccia
author_rank: Super Contributor
timestamp: May 30, 2015, 01:22:39 am
content: Personally, I think we should stop arguing and simply let evolution run it's course.

author: helius
author_rank: Super Contributor
timestamp: May 30, 2015, 01:55:50 am
content: Quote from: Ian.M on May 28, 2015, 10:29:07 pmI have a question about this. Do both leads need to be fused? If only one, does it matter if it is the high or low side (or the + or common jack?)

author: nanofrog
author_rank: Super Contributor
timestamp: May 30, 2015, 02:34:16 am
content: Quote from: helius on May 30, 2015, 12:39:27 amI've Cooper-Busmann's that have the woven body you describe, but the Siba's I have, use a smooth, unglazed porcelain/ceramic type of finish (may not actually be a ceramic type of material, just the best description I can give).FWIW, I do have a blown Siba sitting around I kept for the P/N, just never bothered to tear it apart (P/N =5019906.11). Maybe time to break out the Dremel...

author: retiredcaps
author_rank: Super Contributor
timestamp: May 30, 2015, 02:45:45 am
content: Quote from: nanofrog on May 30, 2015, 02:34:16 amModemhead had pictures of his Cooper Bussmann fuse. If I remember the story correctly, he forgot to change back the probes back to the appropriate input jacks while measuring mains?http://mrmodemhead.com/blog/inside-a-multimeter-fuse/

author: Ian.M
author_rank: Super Contributor
timestamp: May 30, 2015, 03:04:13 am
content: Quote from: helius on May 30, 2015, 01:55:50 amBoth. Otherwise you cannot safely make a phase to phase measurement.The fuses are for protection if the leads get damaged, and if an unfused lead clipped to neutral or earth drags across a sharp edge on a live terminal, you are going to get arc flash. At best, with the right PPE it will ruin your week, at worst, it would be preferable if it actually kills you outright.

author: Muxr
author_rank: Super Contributor
timestamp: May 30, 2015, 03:20:40 am
content: Fear the arc flash:

author: joeqsmith
author_rank: Super Contributor
timestamp: May 30, 2015, 04:32:08 am
content: I have been reading 61010-2-033:2012.Part 2-033: Particular requirements for HAND-HELD MULTIMETERSand other METERS, for domestic and professional use,capable of measuring MAINS voltageI assume this is what they mean when they test to when the refer to 1010. It is very interesting.Setup a simple experiment to create the 8/20 waveform. I did not have the parts needed, but came up with something more like an 4/8, up to 4KV. Only makes about 500A with a 2 ohm source. Really not talking about a lot of energy. I didn't want to get too crazy with it, so left off the mains and just hit the BK with the spike alone to see if the meter would handle it. I assume if the generator is on a 50A service, with 220 mains, all hell's going to break loose if the meter has any sort of internal breakdown.So I started out just using 2KV with the meter in DC volts. Meter is CAT II. Wasn't expecting much with such a short pulse and low voltage. Picture shows damage after one hit in the positive direction. Sorry, I did not make a video of it.Would have been fun to see what would have happened on a real setup.This meter was marked CAT II. I expected it to take handle this little test with ease. Really curious now about other meters. After this experiment, if I actually ever needed to check something on a CAT III or IV setup, I would need to see the mfg's test report before I would even consider it.. Then I would take out an insurance policy.... There is no way I would just trust any meter, even if it has a lot of marks on it and it costs X that it would not flash over.So explode when abused, sure.

author: paulie
author_rank: Frequent Contributor
timestamp: May 30, 2015, 04:48:06 am
content: Looks like "explode" is in the eye of the beholder. When the dial from Dave's Fluke blows off across the room everything is "good as gold" even though obviously destroyed by the blast. But no explosion here. A chip with pit or black mark on the PCB definitely cause to call the bomb squad. This does seem to be one of the more entertaining threads to come along in a while. Not so much technical but more a study in human psychology.

author: joeqsmith
author_rank: Super Contributor
timestamp: May 30, 2015, 05:10:24 am
content: "burst or shatter violently and noisily as a result of rapid combustion, decomposition, excessive internal pressure, or other process, typically scattering fragments widely."Yea, an explosion.... just not on an epic scale. Again, the real energy is from the mains after the flash over. Because there were no mains involved, the explosion was minimized. Sorry, there is no way I would consider attempting a scaled down lines test. I am not setup for it.Dang, I was way off on my post..... Here is the waveform that exploded the BK on an ant scaleC1, is looking at current with a Pearson current transformer. The scale is 0.1 volts per Amp or 200 Amps/div. C2 is using one of my new homemade 100X probes. 1KV/div Rise time is really maybe 3nS ad 200nS width. Imagine a real test setup....

author: paulie
author_rank: Frequent Contributor
timestamp: May 30, 2015, 05:54:28 am
content: Quote from: joeqsmith on May 30, 2015, 05:10:24 amSorry but from my viewpoint it was more like "one fragment scattered closely" rather than "fragments scattered widely". Some of the videos posted did show what I consider explosions but unless at the least case flies apart no explosion. Only harm would come to those inside the case.I am interested in better description though. Not sure what BK is and was that 2 kilovolts at 500 amps? If so we have different idea of what's "not talking about a lot of energy".So with previous mention of scope and cfl supplies it looks like I will have to reproduce my kv geiger accidents except on purpose this time and document. My HF meter worked fine afterwards but we were talking microamps not amps. Stay tuned.

author: joeqsmith
author_rank: Super Contributor
timestamp: May 30, 2015, 01:00:22 pm
content: QuoteWell, you could start by reading the standards they test to.Think in terms of Joules, not Watts. Time. So again, the duration is very short compared to what the standards call for (<< Joules). Now again consider that once that energy dissipates, that's it. If there were an infinite supply of energy (AKA the power lines) that could continue to feed the fire, we get some scary things happening.So, say it was a square pulse I hit it with (obviously it was not). Power = VI or 2KV *500A or 1MW. You think, WOW that's a lot of free energy! But we need to consider it was only there for 200ns. Energy = Power * Time.With the line sure we may only have a few hundred volts and much lower currents, but time is much much much larger.. While the device we tested may have required a small amount of energy at a few KV to start the reaction, it only needs a very small voltage to sustain it. Think about how a TIG welder works.Hope this helps clear up the difference between power and energy.

author: dom0
author_rank: Super Contributor
timestamp: May 30, 2015, 01:07:05 pm
content: The impulse in the scope shot above has about ~40 mJ ... that's like, nothing, but still enough to blow the chip and destroy the meter.

author: paulie
author_rank: Frequent Contributor
timestamp: May 30, 2015, 02:15:11 pm
content: Quote from: Shock on May 30, 2015, 10:47:45 amAre you kidding me? ILOVEhearing this stuff. Getting guys like you going is one of the main reasons to keep coming back here. Hooking borderline personalities is every trolls dream. Actually it's better than just trolling for me... more like shooting the fish in a barrel.... no tackle or lines required. LOLI never initiate personal attacks. Ever. But when dudes like you and Lightage start I do enjoy playing. Please continue. But I do think you can do better than that. Maybe slightly less lame next time.

author: paulie
author_rank: Frequent Contributor
timestamp: May 30, 2015, 02:24:20 pm
content: Quote from: joeqsmith on May 30, 2015, 01:00:22 pmUnfortunately I can't do that. If caught I could lose membership in the anti-safety league.All seriousness aside, I am more interested in the actual meter you used and the equipment for the test. Obviously more of a science experiment and not something the average arduinotard hobbyist would encounter but still interesting. Kinda like the equipment in that Fluke "public service" video (http://mjlorton.com/forum/index.php?topic=821.0). Maybe a photo or at least more info on that meter and test setup.

author: Fungus
author_rank: Super Contributor
timestamp: May 30, 2015, 02:50:32 pm
content: Quote from: paulie on May 30, 2015, 02:15:11 pmYou think you're a maverick but really you're just a redneck and all you're 'constructing' is this:The only reason anybody's bothering with you is you haven't figured out that hundreds of newbies might be reading extracts of this via google results and thinking there's no difference between a $4 multimeter and a $40 Fluke.

author: paulie
author_rank: Frequent Contributor
timestamp: May 30, 2015, 03:13:52 pm
content: Yeeeee... Hawwwww !!! The more fish in that barrel the merrier. Specially such fine members of the community defending truth and justice (if not American Way) from troglodytes like me. gnawww... gnawwww... LOLAnd BTW I do know the difference. Exactly $36 USD. And with some element of "Lamborghini Syndrome" and touch of FUD.

author: Simon
author_rank: Unknown
timestamp: May 30, 2015, 06:48:10 pm
content: Quote from: paulie on May 30, 2015, 02:24:20 pmWell for your information we ban people like you here. So which is it going to be ?

author: Lightages
author_rank: Unknown
timestamp: May 30, 2015, 06:51:17 pm
content: Quote from: paulie on May 30, 2015, 02:15:11 pmPlease show me where I made a personal attack on you, and not and attack on your actions or assertions. If you show me a personal attack I will apologize. I can show you where you have made personal attacks if you really care.

author: Fungus
author_rank: Super Contributor
timestamp: May 30, 2015, 07:14:13 pm
content: Quote from: joeqsmith on May 30, 2015, 03:57:04 pmThe Internet would be all over it if even the cheapest Fluke broke down or didn't meet the rating printed on the front.Uni-T? It seems like a crap-shoot. Dave's covered an unsafe Uni-T that cost him$180of his own money:

author: Fungus
author_rank: Super Contributor
timestamp: May 30, 2015, 07:15:49 pm
content: Quote from: paulie on May 30, 2015, 03:13:52 pmPlease be sure to hold the meter in your hand the next time you connect one to mains in the "Ohms" or "Amps" range. Trail the wires across your arm. Let's see if you think $36 is worth it or not.

author: paulie
author_rank: Frequent Contributor
timestamp: May 30, 2015, 08:06:16 pm
content: Quote from: Lightages on May 30, 2015, 06:51:17 pmQuote from: Lightages on May 27, 2015, 05:28:09 pmCalling somebody a crapper and bullshitter is pretty mild as insults go, certainly not on a par with Shockie, but so was my response. And I didn't say I never engage in personal attacks, I just don't INITIATE them.Anyway I got a PM threat so looks like some comments made in the other forum about dannyf may have awakened sleeping giants. Probably a good idea to close this thread before I end up like him. Truth and justice not always a high priority but I think a few of the "silent majority" may have reason to rethink prevailing belief systems.

author: Tomorokoshi
author_rank: Super Contributor
timestamp: May 30, 2015, 08:20:21 pm
content: One thing to keep in mind:When it comes to safety standards like 61010, 60079, CSA 22.2, NFPA 70 (The NEC in the U.S.), along with all the others out there, a significant percentage of the sections in those standards come about because someone got hurt, something caught on fire, or something blew up.

author: Shock
author_rank: Super Contributor
timestamp: May 30, 2015, 09:16:16 pm
content: Quote from: paulie on May 30, 2015, 02:15:11 pmWhy did you quote my message to the OP in the other thread and write the below?Quote from: paulie on May 28, 2015, 12:30:54 pmAll I did was offer the original poster advice, I wasn't talking to you at all. Looks pretty personal and directed to me paulie. Then you started this thread with:Quote from: paulie on May 28, 2015, 07:15:47 pmIronic since the hijacking was done by you. The moderators aren't dumb, you can't hide behind the playground "I didn't start it". They can read with their own eyes and determine if you were being a dickhead. Which apparently you were since you admit you were trolling.Quote from: paulie on May 30, 2015, 02:15:11 pmNot as much fun as seeing Trolls get banned.Quote from: paulie on May 30, 2015, 08:06:16 pmKeep waiving the flag on this sinking ship captain she's going down with a crew of one!

author: Lightages
author_rank: Unknown
timestamp: May 30, 2015, 11:25:49 pm
content: Quote from: Fungus on May 30, 2015, 07:14:13 pmActually if Dave had just searched his own forums he would seen all the same complaints he raised already documented in detail. The first one was my post about this meter in 2010.

author: Lightages
author_rank: Unknown
timestamp: May 30, 2015, 11:30:17 pm
content: Quote from: paulie on May 30, 2015, 08:06:16 pmAnd where did I attack you? So you can't show I attacked you, only that I attacked your actions and assertions but that still counts as a personal attack. Yes, you do have more fun with your wild assertion and accusations just like you said. Perhaps you got up on the wrong side of the bed when you started these rounds of attacks, but to continue them does show your agenda and you have even said that you are trolling here. So I will stop responding to self admitted trolls. My apologies to everyone else for feeding him.

author: EEVblog
author_rank: Unknown
timestamp: May 31, 2015, 01:39:14 am
content: Quote from: paulie on May 30, 2015, 02:15:11 pmAnd that's how you get yourself banned on a forumBTW, heads up, Paulie uses many different IP addresses to post so he could sneak back in under another name.

author: EEVblog
author_rank: Unknown
timestamp: May 31, 2015, 01:42:53 am
content: Quote from: Fungus on May 30, 2015, 07:14:13 pmThat pretty much sums up Uni-T.They do make a couple of reasonably well made meters for the price, it's shame they have ruin it with a whole bunch of crap moels.It doesn't help when their model numbering system is confusing. e.g. a UT-61D is completely different to a UT-61E

author: John Coloccia
author_rank: Super Contributor
timestamp: May 31, 2015, 02:02:20 am
content: Honestly, I'm surprised that BK Precision meters don't get more love around here. IMHO,unless you really need the durability of a Fluke, they seem to hit a great price/performance point...usable continuity test, fast auto-ranging, decent probes, good build quality, reasonable input protection, generally good performance. I've used a lot of the cheaper meters, and I have an Extech kicking around, but dollar for dollar, I still like BK best out of the lower priced meters.

author: Muxr
author_rank: Super Contributor
timestamp: May 31, 2015, 03:50:07 am
content: Quote from: John Coloccia on May 31, 2015, 02:02:20 amBK 393 looks pretty interesting I must say. Not sure why they aren't more popular.

author: John Coloccia
author_rank: Super Contributor
timestamp: May 31, 2015, 01:23:48 pm
content: Joe, how did you kill the BK in the first place?

author: saturation
author_rank: Super Contributor
timestamp: May 31, 2015, 01:41:43 pm
content: A simple answer to the OP question and linked discussion is that the risk of explosion, or injury to the operator for other reasons such as burns or electric shock, rises with the CAT conditions the DMM is applied too.As a rule, the safety capacity of a DMM should be tied to its maximum measurement capability because a user may use a DMM up to those limits, underanyCAT conditions, despite the CAT rating being written on the DMM.Unless the DMM is 3rd party certified by a NRTL rated safety organization, like UL or ETL, a buyer cannot know if the printed CAT limit is correct.Finally, the build quality could cause the meter to malfunction at a random period later in its life without warning. This could be anywhere from simply drifting off calibration to a full failure, so if you use a tool for high reliability, you are best getting multiple DMMs or/and a model with a reputation for reliability.

author: tru
author_rank: Regular Contributor
timestamp: May 31, 2015, 02:08:08 pm
content: Quote from: Fungus on May 28, 2015, 09:01:08 pmWell, even a Fluke can almost explode. My electrician colleague had his fluke voltage tester T90 (not a multi-meter but voltage tester) measure 3 phase (400V) then boom, the top part of the tester, i.e. the red probe split opened and you could see the burnt stuff inside. Anyway he still only trusts Fluke but now only buys any higher version than the T90.

author: Monkeh
author_rank: Super Contributor
timestamp: May 31, 2015, 02:28:01 pm
content: Quote from: tru on May 31, 2015, 02:08:08 pmAny device can fail under extreme circumstances or as a result of manufacturing defect, the difference is that some don't even attempt to avoid failure!

author: joeqsmith
author_rank: Super Contributor
timestamp: May 31, 2015, 04:22:07 pm
content: Quote from: John Coloccia on May 31, 2015, 01:23:48 pmI blew the IC back on page 3. You can see the waveform there as well. I was actually surprised this killed it.The original damage was maybe 3 or so years ago. Meter was well over 10 years old by that time. I was looking at a HV DC supply with it but was well below the limit of the meter. Then the meter's readings started to become erratic. Changed the battery and it was still doing it. Then it self healed.While doing this, the current on the supply was not changing so it was not like something was breaking down.What is interesting is that the meter had not been turned on for the last several years. I put a battery in it and swept the input to 1KV like it did with the other low cost meters and saw no problems. Maybe the selector switch had started to wear out.Quote from: Muxr on May 31, 2015, 03:50:07 amI would like to try one myself.I like Fluke's intrinsically safe meters. I had seen a youtube video on it and it look very well protected. Potted fuse, etc. If I were going for what I would consider safe, this is where I would start.http://www.fluke.com/fluke/auen/solutions/intrinsically-safe/

author: smjcuk
author_rank: Frequent Contributor
timestamp: June 02, 2015, 03:07:49 pm
content: Damn so I go on holiday for a bit and the place has gone crazy

author: bc888
author_rank: Regular Contributor
timestamp: October 09, 2018, 08:39:11 pm
content: Noob sniffing around for info and thought this was germaine to the conversation:https://www.eevblog.com/forum/testgear/oops!-i-think-i-want-a-new-multimeter/msg1108720/#msg1108720