EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: Fungus on April 11, 2023, 06:32:09 pm
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After the previous "trashy" meter thread I was curious so I spent this month's fun money on some of Big Clive's favorite meter the Duratool D03047.
The meters cost me €3.78 each (+tax) but the only place I could find them was on Farnell where there's a minimum shipping fee of €14. >:(
Oh, well. In for a penny, in for a pound... I ordered three of them to make the postage worthwhile. They arrived today:
(https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1759469;image)
The nicely-printed box they come in shows a yellow meter but they were black on the inside, just like Clive's.
(https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1759475;image)
First impressions are of a well made DT830 in a rubber boot. The dial is clicky, the printing on the front is very easy to read.
(Clive says the rubber boot gives it a "cheap, Fluke-like appeal" and he's right. I like the way it feels in the hand...)
Opening it up: The plastic case isn't what I'd call "thick" but it's thick enough. Certainly not eggshell thin like some other DT830s I've seen.
Inside we see more "DT830 done right". There's two ceramic fuses for the different current ranges, a beeper, and the quality of the PCB, etc., is very good apart from a bit of flux residue around the hand-soldered parts.
Little details stand out, eg. The 5A current shunt is sleeved for some reason. The strain relief on the battery cable looks good - I've see DT830s where the battery cable breaks off almost every time you take the back off.
(https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1759481;image)
The input jacks are solid tubes (not the rolled/split-metal type) and are soldered to a small daughterboard. They look quite sturdy. The daughterboard has the 5A fuse soldered to it. The 500mA fuse is clipped to the main PCB. The fuses are marked "500V".
(https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1759493;image)
The probes it comes with aren't the best (obviously) but they aren't the worst either. They're certainly a step up from the average DT830 probe.
They're fully shrouded and fit very tightly in the meter (probably thanks to the solid input jacks).
(https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1759715;image)
The safety claim is "CAT I 500V". That seems slightly overcautious but I'm not going to argue. I didn't buy it to work on mains AC.
(https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1759499;image)
The back of the meter has a batch number lasered onto it. A sign of real factory quality control processes?
(https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1759505;image)
I did a few function tests:
Volts was spot on
Amps was spot on
Ohms was about three counts too low on 10k+1k resistors.
Continuity is latched, medium-loud, not very fast.
The square wave function outputs a 50Hz, 2.2V square wave.
Diode test is ~3V open circuit, it lights up my big white test LED, no problem.
(https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1759523;image)
There's no backlight but the display is incredibly contrasty.
Power consumption is under 300uA so the battery should last for thousands of hours (plural).
The manual is surprisingly(refreshingly?) specific about overload protection on each range:
(https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1762292;image)
(https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1762298;image)
Verdict: I like it! I nominate this for "cheapest meter that's actually worth owning". :-+
Could it replace my Anengs? Answer: Yes. The only thing I might miss would be auto-ranging on the Ohms range.
(it's also a lot smaller/cuter than most of them and costs a fraction of the price. ;D )
It's hard to believe they can sell this for €3.78 through reputable sellers in Europe.
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Ref: "Trashy meters"
https://www.youtube.com/watch?v=-QDW0LRQVrY (https://www.youtube.com/watch?v=-QDW0LRQVrY)
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I have bought sub £10 multimeters before and they do work a bit.
I usually find low ohms readings are off.
I spent about £25 on a Kaiweets multimeter and that has been much better.
Low ohms readings are spot on.
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I have bought sub £10 multimeters before and they do work a bit.
I usually find low ohms readings are off.
Let's see...
I shorted the probes on the 200 Ohm range and it said "0.4".
I measured a 2 Ohm resistor and it said "2.3".
Seems good to me!
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I don't get it- why do people buy stuff like this?
I mean, I'd get buying one for a kid that wants to measure a few batteries I guess, but do people get this stuff for morbid curiosity, or to collect, or for doing actual work? I genuinely don't understand the appeal :-//
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I don't get it- why do people buy stuff like this?
I mean, I'd get buying one for a kid that wants to measure a few batteries I guess, but do people get this stuff for morbid curiosity, or to collect, or for doing actual work? I genuinely don't understand the appeal :-//
Me? I can't imagine a world where not a single person would want to own one just for the fun of it.
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Edit: Title changed in case anybody wants to search for this meter on google
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I don't get it- why do people buy stuff like this? I mean, I'd get buying one for a kid that wants to measure a few batteries I guess, but do people get this stuff for morbid curiosity, or to collect, or for doing actual work? I genuinely don't understand the appeal :-//
as long as you're not measuring anything over 50v or so, these meters are perfectly adequate. and compared to any analog meter (i remember the days before DMMs were available) the accuracy is pretty impressive. not to forget the minimal power consumption of the ICL7106 chip that invariable runs the meter.
what lets these meters down is the cost-cutting to the nth degree. if you just doubled the build cost the meters could be so much better with:
1. separate current terminals, so have a 4th terminal for uA and mA;
2. powered by 6x AA cells instead of a PP9;
3. NO higher voltage ranges;
4. NO transistor tester.
cheers,
rob :-)
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I wonder if the sleeve on the shunt is to stop sparks jumping to COM from the other input jacks?
It seems unnecessary in a meter with this rating but I can't think of any other reason.
(https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1759493;image)
Maybe they assume that not everybody knows what "CAT I" means.
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Never seen a sleeve on a shunt like that. In this case may the owner grabs a deep banana jacked leads (or a nail) and shorts the shunt to common. The sleeve may help prevent that, once....
Harbor Freight changed the max voltage marking on their free meters. Of course, they can still read well about it. Seems like 2kV?
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Never seen a sleeve on a shunt like that. In this case may the owner grabs a deep banana jacked leads (or a nail) and shorts the shunt to common. The sleeve may help prevent that, once....
That's Clive's theory, too, see his video at 21:16 onwards.
The shunt's quite a long way off to the side of the input jacks though (see video). An extra long banana plug wouldn't touch it.
If people are poking mains wires directly into the input jacks of multimeters then most bets are off anyway. I wonder if Flukes protect people from that?
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Everyone has a different use case, priority, budget, and economic resources. While this may not be the preferred meter for someone who frequent this forum, it may be perfectly adequate for many. I am sure the existence of such meter enabled many to become interested in electronics and turned it into a career. So I am grateful of such meters, I have no problem with them as long as they state the limitations properly, so informed buyers will not doing something stupid with them and get hurt as a result.
But I do agree with many of you that I would not use it for high voltage work, I got about 4 of such meters from Harbor Freight (3 of them were free), the leads from each of them broke in different fashion, with wires coming out from either end, and that’s with minimal use. User can easily get a shock if it is used in HV scenario.
I don't get it- why do people buy stuff like this?
I mean, I'd get buying one for a kid that wants to measure a few batteries I guess, but do people get this stuff for morbid curiosity, or to collect, or for doing actual work? I genuinely don't understand the appeal :-//
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I got about 4 of such meters from Harbor Freight (3 of them were free), the leads from each of them broke in different fashion, with wires coming out from either end, and that’s with minimal use.
The typical "Harbor Freight" leads are very weak. The probe handles are hollow tubes (see pic above) so the wires can twist around inside them and eventually break off.
The secret is to inject a bit of hot glue in the end of the tubes. :)
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I don't get it- why do people buy stuff like this?
I mean, I'd get buying one for a kid that wants to measure a few batteries I guess, but do people get this stuff for morbid curiosity, or to collect, or for doing actual work? I genuinely don't understand the appeal :-//
Me? I can't imagine a world where not a single person would want to own one just for the fun of it.
Yeah I guess I just don't get what "the fun of it" is supposed to be with these things? Like is it the "I got a bargain" feeling if it works or something?
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Everyone has a different use case, priority, budget, and economic resources. While this may not be the preferred meter for someone who frequent this forum, it may be perfectly adequate for many. I am sure the existence of such meter enabled many to become interested in electronics and turned it into a career. So I am grateful of such meters, I have no problem with them as long as they state the limitations properly, so informed buyers will not doing something stupid with them and get hurt as a result.
But I do agree with many of you that I would not use it for high voltage work, I got about 4 of such meters from Harbor Freight (3 of them were free), the leads from each of them broke in different fashion, with wires coming out from either end, and that’s with minimal use. User can easily get a shock if it is used in HV scenario.
I don't get it- why do people buy stuff like this?
I mean, I'd get buying one for a kid that wants to measure a few batteries I guess, but do people get this stuff for morbid curiosity, or to collect, or for doing actual work? I genuinely don't understand the appeal :-//
Yeah I can totally understand someone going "I have X dollars, this is literally my only option", 100%. It just baffles me that anyone else would buy one. Having owned shit like that myself when I was broke and starting out I was so glad to get rid of it at the first chance I got and be able to actually trust my tools. But hey, people collect shit like stamps and spoons, to each their own, I'd just love to know what the draw of these things is?
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Like is it the "I got a bargain" feeling if it works or something?
Nope. Not even close.
Yeah I can totally understand someone going "I have X dollars, this is literally my only option", 100%. It just baffles me that anyone else would buy one. Having owned shit like that myself when I was broke and starting out I was so glad to get rid of it at the first chance I got and be able to actually trust my tools. But hey, people collect shit like stamps and spoons, to each their own, I'd just love to know what the draw of these things is?
I guess this is a bit like humor: If I have to explain it to you then you'll never really appreciate it, but here goes...
Leaving aside the fact that I don't recall a DT830 ever giving me a reason not to trust it (they either work or they don't) and the fact that I believe I get more "trust" from owning several cheap meters that agree with each other than by owning a single monolithic multimeter, no matter how expensive, I can come up with plenty of reasons to buy meters like this:
a) You can own lots of them and leave them in different places where they might be needed.
b) You can use them in bars where they might get beer or allioli spilled on them (ie. Arduino club meetings).
c) They're small and fit in cases/pockets easily, no special protective case needed.
d) You can use them at shows or places where an expensive meter might go missing if you take your eye off it.
e) You can let other people use them without worrying they'll drop them or scratch the screen or blow a $15 fuse with an AA battery.
f) You can give them away to beginners or other people who don't have a meter yet, turn them into enthusiasts.
g) It's just plain good fun to open new things and learn from what's inside them.
(See Clive's video for more reasons...)
Any info about this sort of meter is useful and these seem like worthwhile meters to me, hence the post.
PS: Have you never, ever, collected anything at all?
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Like is it the "I got a bargain" feeling if it works or something?
Nope. Not even close.
Yeah I can totally understand someone going "I have X dollars, this is literally my only option", 100%. It just baffles me that anyone else would buy one. Having owned shit like that myself when I was broke and starting out I was so glad to get rid of it at the first chance I got and be able to actually trust my tools. But hey, people collect shit like stamps and spoons, to each their own, I'd just love to know what the draw of these things is?
I guess this is a bit like humor: If I have to explain it to you then you'll never really appreciate it, but here goes...
Leaving aside the fact that I don't recall a DT830 ever giving me a reason not to trust it (they either work or they don't) and the fact that I believe I get more "trust" from owning several cheap meters that agree with each other than by owning a single monolithic multimeter, no matter how expensive, I can come up with plenty of reasons to buy meters like this:
a) You can own lots of them and leave them in different places where they might be needed.
b) You can use them in bars where they might get beer or allioli spilled on them (ie. Arduino club meetings).
c) They're small and fit in cases/pockets easily, no special protective case needed.
d) You can use them at shows or places where an expensive meter might go missing if you take your eye off it.
e) You can let other people use them without worrying they'll drop them or scratch the screen or blow a $15 fuse with an AA battery.
f) You can give them away to beginners or other people who don't have a meter yet, turn them into enthusiasts.
g) It's just plain good fun to open new things and learn from what's inside them.
(See Clive's video for more reasons...)
Any info about this sort of meter is useful and these seem like worthwhile meters to me, hence the post.
PS: Have you never, ever, collected anything at all?
Not really :-// Maybe music I guess, but not as a collector, just as a lifelong music fan/musician that wanted to listen to it all.
For me meters are just tools rather than anything I'd think about collecting. Like I'm not going to go buy 12 cheap screwdrivers in case I need to take one on holiday, keep one in the car, have one to display and so on, I'm just going to buy a good one and look after it. I'll generally only grab a second one if I find I need two at once.
I guess though I've got a very different take on the trust thing too, maybe partly because I'm generally working at higher voltages. If I'm sticking my fingers in a 600V circuit I feel confident that my good meters are telling me the truth about what's there. I'm not worried that I left them on a little long last week and the battery has faded and thrown readings off or the banana terminals have cracked solder joints or something like that. I also don't want to have to double check a measurement with 3 different meters to get confidence in a reading.
Hey, you do you, whatever floats your boat. I've just always wondered about this, especially when I see guys like Clive using them when he could very likely choose a better made unit.
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I will share my use case for my Harbor Freight meters.
When I work on electrical problems on my cars or tractors, I don’t need accuracy and precision, often all I need to see is whether it is receiving power, or rough voltage. While working in the engine compartment, my gloves are covered with grime, oil, smudges, hydraulic fluid, etc…. It leaves a greasy black smudge on everything I touch. While I have nice Fluke and Brymen handhelds, the black oil and smudge will never come off the case, and it will fill every cracks. Since I am working on low voltage with no need for accuracy, I can care less about what happens to the HF meters, if they get trashed, into the trash they go. I view them as disposable meters for truly dirty work.
DMM is like dishes at home, there is fine China, there is everyday dishes, they is plastic and paper disposable dishes. There is nothing wrong to have more than one type of dishes.
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Yep, kept one in my vehicle for years. Didn't care what happened to it. Eventually the battery corroded and I threw it out (should have repaired it though). No doubt it would have still worked.
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I will share my use case for my Harbor Freight meters.
When I work on electrical problems on my cars or tractors, I don’t need accuracy and precision, often all I need to see is whether it is receiving power, or rough voltage. While working in the engine compartment, my gloves are covered with grime, oil, smudges, hydraulic fluid, etc…. It leaves a greasy black smudge on everything I touch. While I have nice Fluke and Brymen handhelds, the black oil and smudge will never come off the case, and it will fill every cracks. Since I am working on low voltage with no need for accuracy, I can care less about what happens to the HF meters, if they get trashed, into the trash they go. I view them as disposable meters for truly dirty work.
DMM is like dishes at home, there is fine China, there is everyday dishes, they is plastic and paper disposable dishes. There is nothing wrong to have more than one type of dishes.
That I get, 100%. Totally usable as a disposable yes/no meter if things aren't mission critical
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I will share my use case for my Harbor Freight meters.
When I work on electrical problems on my cars or tractors, I don’t need accuracy and precision, often all I need to see is whether it is receiving power, or rough voltage. While working in the engine compartment, my gloves are covered with grime, oil, smudges, hydraulic fluid, etc…. It leaves a greasy black smudge on everything I touch. While I have nice Fluke and Brymen handhelds, the black oil and smudge will never come off the case, and it will fill every cracks. Since I am working on low voltage with no need for accuracy, I can care less about what happens to the HF meters, if they get trashed, into the trash they go. I view them as disposable meters for truly dirty work.
DMM is like dishes at home, there is fine China, there is everyday dishes, they is plastic and paper disposable dishes. There is nothing wrong to have more than one type of dishes.
Though I strongly agree in "Buy once, Cry once", and I tend to despise waste so I understand where some posters are coming from, the description quoted above couldn't have been said better. There is a time and a place for disposable equipment. Gloves would be another good example. I don't use my deerskin gloves to change the oil. If you intend to not treat it like the disposable meter it is, then I suggest you do yourself a favor.
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DMM is like dishes at home, there is fine China, there is everyday dishes, they is plastic and paper disposable dishes. There is nothing wrong to have more than one type of dishes.
Yep. I wouldn't eat off disposable dishes at home but if I'm just grabbing something to eat there's my favorite chipped plate...
It's not the whole picture though. Refusing to touch anything but Flukes seems to me like a certain person sitting at a roped off table in a gold plated country club: I'm sure it's a fine dining experience and all but last night I sat on a hard metal chair on a noisy street corner, eating a kebab and drinking straight out of a can. Donald will never experience that, so all he'll never have a reference point to truly appreciate the finer stuff.
I'm a bit of a Clive at heart, I'll sit on noisy street corners for fun and I will use this meter. It's cute, it's clicky and it amuses me to do so.
Though I strongly agree in "Buy once, Cry once", and I tend to despise waste so I understand where some posters are coming from, the description quoted above couldn't have been said better. There is a time and a place for disposable equipment. Gloves would be another good example. I don't use my deerskin gloves to change the oil. If you intend to not treat it like the disposable meter it is, then I suggest you do yourself a favor.
Here's another curveball...
I also own one of these: https://www.aliexpress.com/item/1005004478400063.html (https://www.aliexpress.com/item/1005004478400063.html)
On paper it's completely useless - can't even measure voltages below 0.8V(!), but I find myself using it a lot lately.
(https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1760690;image)
As Clive notes: Manual ranging multimeters spend most of their time in either the 20V or continuity-test ranges and I'm sure we can all relate to that.
My little Zoyi switches between those two ranges on the fly. Hold the black probe on GND and poke around: If you touch a ground pin it beeps, if you touch a power pin it shows the voltage there. High impedance? It shows a resistance.
To switch to current measurement you just move the cable to the mA input. That's it. No need to touch a dial or do anything else, it senses the probe in the input jack and switches over to current measurement all by itself.
(it also tuts at you disapprovingly if you leave the probe there and there's no current flowing, which is cool)
It also reads voltages unbelievably fast. You know the game where you bang your probes together in continuity mode to see if you can beat the beeper? With this meter you can play that game with voltage measurements and the meter will win most of the time.
I'd never have known any of this if I hadn't spent my "fun money" on one a few months ago.
I will share my use case for my Harbor Freight meters.
When I work on electrical problems on my cars or tractors, I don’t need accuracy and precision, often all I need to see is whether it is receiving power, or rough voltage. While working in the engine compartment, my gloves are covered with grime, oil, smudges, hydraulic fluid, etc…. It leaves a greasy black smudge on everything I touch. While I have nice Fluke and Brymen handhelds, the black oil and smudge will never come off the case, and it will fill every cracks. Since I am working on low voltage with no need for accuracy, I can care less about what happens to the HF meters, if they get trashed, into the trash they go. I view them as disposable meters for truly dirty work.
You need one of those ^^
It's one of the physically toughest meters ever made. Run over it with your tractor and it won't care (remember to upload the video).
There's also no dial to turn, just a single button to use it.
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I guess though I've got a very different take on the trust thing too, maybe partly because I'm generally working at higher voltages. If I'm sticking my fingers in a 600V circuit I feel confident that my good meters are telling me the truth about what's there.
That's a whole other scenario, nothing to do with what's being discussed here.
PS: Clive says he uses Flukes at work.
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I guess though I've got a very different take on the trust thing too, maybe partly because I'm generally working at higher voltages. If I'm sticking my fingers in a 600V circuit I feel confident that my good meters are telling me the truth about what's there.
That's a whole other scenario, nothing to do with what's being discussed here.
PS: Clive says he uses Flukes at work.
It isn't really clear what's being discussed here other than cheap meters. Is there a specific voltage or accuracy spec I missed in your post?
That'd make sense about Clive, I was always puzzled seeing those meters in his vids.
I don't really get the thing in your other post either about refusing to use cheap tools being like "sitting at a roped off table in a gold plated country club". It's not at all like a kebabs vs fine dining thing. Good tools aren't about elitism or being "finer stuff", the point is for them to help get the job done properly and quickly. It's also relative- if you're a hobbyist you might think a $500 or whatever meter is overkill, but if that's how you make your living the goalpost of what a tool is worth shifts pretty quickly. I'm a very low level hobbyist/shithouse machinist so it's hard for me to justify hundreds of bucks on a set of calipers for myself, but I'm not about to suggest that any machinist insisting on proper Mitutoyos over bargain bin ones is being too precious about their tools.
Case in point- 45 minutes ago I was on a callout where I needed to make a couple power supply adjustments on a pretty damn expensive bit of gear that I'd rather not stuff up and have to fix for free. The client isn't just paying for expertise, they're also paying for the peace of mind that if your meter says it's XYZ volts, then it's XYZ volts, no ifs or buts about it, their gear (read:livelihood) is in safe hands. They don't wanna see me whip out 3 meters to see if they all agree (and god knows what you're supposed to do if they don't when the clock is ticking), they wanna see the good stuff and the right reading.
I also used a proper screwdriver for the trimpot. I'm sure we could have gone kebab style and used a fingernail or sharpened stick or something instead, but I don't think they'd feel too great calling me back for the next job if I did that.
With all this said, I 100% get what NoisyBoy said about a good purpose of these things. Or simply just the budgetary thing- if all I have is a $5 meter then that's what I have to use, but from experience you can be damn sure that the first bit of money I make with it is getting dumped into a better one rather than buying another crap one. Hell, "Fuck you I like them" is a perfectly good reason too. I was just trying to understand the attraction.
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Ceramic fuses? :o
https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1759493;image (https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1759493;image)
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...I wonder if Flukes protect people from that?
Don't most of the higher end meters I show have a dead stop, far away from the shunts?
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Ceramic fuses? :o
Yep. And 500V rated!
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"Fuck you I like them" is a perfectly good reason too.
Let's go with that then. :)
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Hell, "Fuck you I like them" is a perfectly good reason too. I was just trying to understand the attraction.
Clive's entire channel and schtick is built on $5 trashy things. Totally on brand for his channel.
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I wonder if that trashy meter carbonates? :popcorn:
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I don't get it- why do people buy stuff like this?
I mean, I'd get buying one for a kid that wants to measure a few batteries I guess, but do people get this stuff for morbid curiosity, or to collect, or for doing actual work? I genuinely don't understand the appeal :-//
I bought one when I was a kid and couldn't afford anyting else.
I bought one when I needed to check something and I was 2 hours away from my other meters.
I bought one for a basic tool kit that stays at a remote radio site (runs on solar, 2h hike from the closest road) just in case someone without tools needs to do a quick check-up
Plenty other reasons why you would by a cheap disposable meter.
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Plenty other reasons why you would by a cheap disposable meter.
Maybe, but when you can get a quite decent $20 class meter these days, I'm not seeing much of a point.
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Clive's entire channel and schtick is built on $5 trashy things. Totally on brand for his channel.
Clive doesn't hold back on the tech stuff, he does a lot of good reverse engineering and explanation of the circuits he finds. inside those trashy things. Some of them are quite ingenious. Making things for $5 isn't easy.
(and others are dangerous and he always explains why... it's all stuff worth knowing)
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Maybe, but when you can get a quite decent $20 class meter these days, I'm not seeing much of a point.
The point is that now we know there's $4 meters that can do it too.
(so long as all you need is basic features)
PS: Don't you make videos along the lines of "What's the cheapest possible microcontroller?" Why should we struggle to use barely-documented, unknown Chinese chips in out projects when we can get mainstream AVR chips for under $1?
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Plenty other reasons why you would by a cheap disposable meter.
Maybe, but when you can get a quite decent $20 class meter these days, I'm not seeing much of a point.
it depends if you have $20 in your wallet, or only $4.
my concern is what happens when you connect real AC mains (that is 230v, not that paltry 110v) to any of the cheaper multimeters. issues of minimum creepage and clearance distances. the likes of Fluke take these quite seriously, the chinese makers of the cheaper brands less so. the reality is that (adherence to) these distances are likely not going to be put to the test by the vast majority of users; but on the odd occasion the some users may find themselves less lucky.
it seems to be that the cost of improving creepage and clearance distances should be quite minimal. either that, or ensure the multimeter tops out at a suitably low voltage (<50v RMS). see: https://en.wikipedia.org/wiki/Low_voltage (https://en.wikipedia.org/wiki/Low_voltage)
cheers,
rob :-)
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my concern is what happens when you connect real AC mains (that is 230v, not that paltry 110v) to any of the cheaper multimeters.
With the dial and leads in the correct position? I'd put my money on "not much apart from displaying the voltage on screen".
Even with the meter in this thread I'd go with "not much".
I haven't traced the circuit out but it appears to be made by a company that takes things seriously. I'd say the only reason they rate it for mains AC is that the lowest applicable rating includes voltage surges of 2500V+ which would be too much for it.
Measuring 230V AC though? Probably OK, although I wouldn't advise anybody to do it - surges happen!
Not everybody goes near mains electricity though and it's perfectly OK to buy one of those meters if you don't.
If you work on mains AC all day long? Get a suitable meter.
PS: Can you put your hand on your heart and swear you always wear gloves, etc. when poking at mains AC with your Fluke?
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my concern is what happens when you connect real AC mains (that is 230v, not that paltry 110v) to any of the cheaper multimeters.
I'd say the only reason they rate it for mains AC is that the lowest applicable rating includes voltage surges of 2500V+ which would be too much for it. Measuring 230V AC though? Probably OK, although I wouldn't advise anybody to do it - surges happen!
not quite sure what you've written is entirely clear, but i think you're asserting that for measuring 230v AC the meter should have a 2.5kv surge rating. with this, i would broadly agree. there are many standards from around the world, but i would agree that being able to withstand a 2.5kv surge is a reasonable compromise for measuring domestic AC.
but are you also saying that it is OK for a piece of test equipment with a scale calibrated up to 250v or more, sold as being suitable for the purchaser to measure domestic AC mains, to not be able to withstand a 2.5kv surge? if this is what you are saying, then, well, why do we even bother having these safety standards?!
i think we all agree that DT-830 style multimeters are not suitable for measuring domestic AC mains voltages. i am just going one step further to suggest that manufacturers and retailers of such multimeters should be held accountable for selling a product that does not comply with the relevant safety standards. ie, farnell should not sell such products, repco and bunnings (or walmart or ASDA) should not sell such products, ebay should not allow such products to be listed on their site.
as an alternative, it should be fine for anyone to sell products that either comply with the relevant safety standards (the Fluke 101 provides a good example), or that are constrained to be usable only within safe limits - that is <50v RMS or thereabouts. either step would not seriously impact the manufacturing cost: remove the 500/1000/2kv ranges, limit the display of 200v ranges so that the multimeter displays an 'over-range' for anything over 72v AC/DC, move current ranges to a separate uA/mA input socket, redesign PCB layout and component choices to meet minimum creepage and clearance distances.
after all, if i were to set up shop selling pairs of rubber kitchen gloves marked in big letters across each glove as "250v safe", how long would i be allowed to stay in business?
PS: Can you put your hand on your heart and swear you always wear gloves, etc. when poking at mains AC with your Fluke?
i take reasonable precautions around mains AC voltages. if i have any doubts about what i am doing, i STOP. that is simple common sense, coincidentally one of the least common commodities in this universe.
cheers,
rob :-)
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but i think you're asserting that for measuring 230v AC the meter should have a 2.5kv surge rating.
It's not an "assertion".
It's the requirement for a meter to be labelled "CAT II 300V", as defined by industry experts.
but are you also saying that it is OK for a piece of test equipment with a scale calibrated up to 250v or more, sold as being suitable for the purchaser to measure domestic AC mains, to not be able to withstand a 2.5kv surge? if this is what you are saying, then...
I'm not saying that at all.
What I'm saying is that I would carefully use this meter to measure 230V mains in a pinch, if there was nothing better around.
Car analogy: Using this meter to measure mains is like driving without a seatbelt. You won't instantly die if you do it, you can probably do it for years and get away with it. I don't recommend it though and I always wear mine.
Careful driving isn't a substitute so that's why I added "If you work on mains AC all day long? Get a suitable meter.".
PS: This meter clearly says "CAT I" on the front so it is not being sold as "suitable for the purchaser to measure domestic AC mains".
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PS: This meter clearly says "CAT I" on the front so it is not being sold as "suitable for the purchaser to measure domestic AC mains"
the DO3047 has 500v written SIX times on the front of it, including the two ranges (AC and DC) labelled 500. an average reasonable person (as defined in law) would be hard pushed to not assume it was safe for making measurements up to 500 volts. the "cat I" text occurs just once. i see that "CAT I describes secondary circuits not intended to be connected to the mains electricity supply" (https://www.flir.com/discover/professional-tools/what-do-cat-ratings-mean/ (https://www.flir.com/discover/professional-tools/what-do-cat-ratings-mean/)). off the top of my head, i can not think where the average person might today encounter such a defined source. in times gone by, perhaps a battery-powered fluorescent lamp? but today, no.
Car analogy: Using this meter to measure mains is like driving without a seatbelt. You won't instantly die if you do it, you can probably do it for years and get away with it
it is a poor analogy, "About 90 people are killed every year on New Zealand roads because they weren't wearing a seatbelt" (https://www.nzta.govt.nz/about-us/about-waka-kotahi-nz-transport-agency/annual-report-2018-19/safety/ (https://www.nzta.govt.nz/about-us/about-waka-kotahi-nz-transport-agency/annual-report-2018-19/safety/)). our front-line police officers have the unpleasant task of attending to those 90 dead, mangled bodies. extrapolating worldwide, that is around 144,000 dead, mangled bodies.
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Hell, "Fuck you I like them" is a perfectly good reason too. I was just trying to understand the attraction.
Clive's entire channel and schtick is built on $5 trashy things. Totally on brand for his channel.
Yeah, I am not sure if the guy has ever used an oscilloscope. Or even knows what it is.
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There is a justifiable real world use case for trashy meters: A school science lab or engineering department requires meters that can be used, abused, destroyed and stolen by pupils, whilst keeping inside the school's diminished science/engineering budget. [ As the school prefers to spend all of its funds on a fully equipped sport gym, next year's budget will be even slimmer. Which will be blown on portable oscilloscopes. ] Chances are, the smart EE students will already have a Fluke or EEVBlog meter at home.
As for the price of these meters, put your production engineering hard-hats on for a moment. Could as a business you design, manufacture, promote and distribute these meters for their western market price point? Very unlikely.
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an average reasonable person (as defined in law) would be hard pushed to not assume it was safe for making measurements up to 500 volts.
An "average person" has no business poking around inside mains distribution panels. It might even be illegal.
Even Dave doesn't do it. He calls in an electrician in the videos where he's connecting up his solar panels, etc.
I assume all electricians:
a) Are aware of what a CAT rating is
b) Would laugh if they were given this meter to work with
it is a poor analogy, "About 90 people are killed every year on New Zealand roads because they weren't wearing a seatbelt"
It's a perfect analogy, you just forgot to contrast with "how many people didn't?"
According to this page: 91,000 people were fined in NZ for not wearing a seatbelt.
https://www.stuff.co.nz/motoring/122306446/traffic-fines-have-cost-kiwis-more-than-272-million (https://www.stuff.co.nz/motoring/122306446/traffic-fines-have-cost-kiwis-more-than-272-million)
(nb. that's just the ones who were caught/fined - the real number will be much, much higher)
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The manual that comes with this meter is surprisingly specific about overload protection on each range:
(https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1762292;image)
(https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1762298;image)
Edit: I'm not sure why it says the 5A range has a 250V fuse, the one inside the meter definitely has "500V" stamped on it.
(https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1762310;image)
Maybe they decided to upgrade the fuse to match the other one after the manual was printed - avoid confusion by having them both the same.
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with just a little photo editing, here is a much more suitable version:
(https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1762418)
note that apart from removing ranges, a small electrical modification would be required so that above 75v an over range is displayed - the continuity buzzer could also be pulsed as an extra warning.
cheers,
rob :-)
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... , i can not think where the average person might today encounter such a defined source. in times gone by, perhaps a battery-powered fluorescent lamp? but today, no.
From the link provided:
CAT I describes secondary circuits not intended to be connected to the mains electricity supply, such as electronics, including a typical laptop PC, and circuits powered by regulated low voltage sources.
I wouldn't consider people involved with this forum being average. I'm sure there are a few of us working with electronics in excess of 500V. I would have no problem using even the free HF meter to measure kV levels as long as the energy is low enough.
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I would have no problem using even the free HF meter to measure kV levels as long as the energy is low enough.
Yep. That's another reason to own them.
I used to use them to monitor voltages when I was in my "Can I make big sparks?" phase (we've all been there...)
They measure 1000V, no problem. Just don't hold them in your hand while you do it.
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They measure 1000V, no problem. Just don't hold them in your hand while you do it.
Why not?
Here are two free HF meters. Newer style on the left is now marked 250VDC compared with the original 1kV marking. Also shown with me holding the new low voltage meter in parallel with the Brymen BM789 with 1kV applied, no gloves. I'm sure there are a few people who would consider this a very unsafe practice but as I said, it comes down to the energy available and your level of education.
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They measure 1000V, no problem. Just don't hold them in your hand while you do it.
Why not?
As a disclaimer to the thread nannies.
Here are two free HF meters. Newer style on the left is now marked 250VDC compared with the original 1kV marking.
But they still measure/display 1kV, right?
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They measure 1000V, no problem. Just don't hold them in your hand while you do it.
Why not?
As a disclaimer to the thread nannies.
It's better to educate with facts than spread fairy tails. My grill starter can put out Amps at several kVs. It would even damage this meter. But I would have no problem surviving a direct pulse from it..
Here are two free HF meters. Newer style on the left is now marked 250VDC compared with the original 1kV marking.
But they still measure/display 1kV, right?
I guess posting it was a kV and having the three meters reading a kV still left you with that question. YES they can still display 1kV. And if someone was thinking that the supplied leads were not safe to use under these conditions, I beg to differ.
If you wanted to promote safe practices, mention the one hand rule.
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As a disclaimer to the thread nannies.
It's better to educate with facts than spread fairy tails.
It's not that, I just don't want to sit through another ten posts on the subject of "safety!!"
Is there anybody here who hasn't been zapped by tens of thousands of volts? I doubt it.
eg. When getting out of a car. After walking on a nylon carpet then touching a door knob.
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Being exposed to ESD is common for the average person. Playing around with DC at kV levels wouldn't be unheard of for those of us on this site. If people are concerned about safety, I suggest using the DOD's safety standard as a guide.
https://www.energy.gov/ehss/doe-electrical-safety-program (https://www.energy.gov/ehss/doe-electrical-safety-program)
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Hell, "Fuck you I like them" is a perfectly good reason too. I was just trying to understand the attraction.
Clive's entire channel and schtick is built on $5 trashy things. Totally on brand for his channel.
For sure. I watch his channel often and like it. I'm just getting pretty strong vibes here that Clive essentially saying "This works OK for $5 and I didn't die" is being taken as "I found a video on the internet that totally backs up my confirmation bias about my $5 meter being the cats ass"
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For sure. I watch his channel often and like it. I'm just getting pretty strong vibes here that Clive essentially saying "This works OK for $5 and I didn't die"
I's almost as if you didn't bother to watch the video. Clive specifically says not to use these "at work".
The only person who mentioned "death" was you.
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Newer style on the left is now marked 250VDC compared with the original 1kV marking.
...which will have no effect at all on number of deaths (if there are any).
People know they have 110V/230V at home so they'll think these meters are good for that.
But they still measure/display 1kV, right?
I guess posting it was a kV and having the three meters reading a kV still left you with that question.
It was kind of rhetorical just to emphasize that nothing changed on the inside. It's only the label that changed.
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Regarding safety of "830" meters, I think the most likely effect of a big transient at home is that they'll go "pop" and cease to function.
nb I don't have any hard data to back that up* but there's plenty of soft data, eg. Harbor Freight isn't involved in any class-action lawsuits for giving away millions of these "devices-of-death".
Me? I'd be much more worried about people putting the leads in the wrong holes and connecting it to mains AC than about transients. The fuses in this meter will make it just as safe as most $20 meters in this situation, if not safer - my Anengs only have 250V fuses in them.
(*) I don't have access to a suitable testing facility.
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Regarding safety of "830" meters, I think the most likely effect of a big transient at home is that they'll go "pop" and cease to function.
nb I don't have any hard data to back that up* but there's plenty of soft data, eg. Harbor Freight isn't involved in any class-action lawsuits for giving away millions of these "devices-of-death".
Me? I'd be much more worried about people putting the leads in the wrong holes and connecting it to mains AC than about transients. The fuses in this meter will make it just as safe as most $20 meters in this situation, if not safer - my Anengs only have 250V fuses in them. ...
I didn't think you wanted to talk about safety.
It was kind of rhetorical just to emphasize that nothing changed on the inside. It's only the label that changed.
Those free meters have gone through several hardware changes over the years to reduce cost. Even if we saw a difference between the two meters I show, I couldn't tell you if it had anything to do with the label or not.
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Those free meters have gone through several hardware changes over the years to reduce cost. Even if we saw a difference between the two meters I show, I couldn't tell you if it had anything to do with the label or not.
Is 1100V the limit? Seems to me like a 2000 count meter should be able to display 2000V... :popcorn:
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If you wanted to promote safe practices, mention the one hand rule.
OK. When measuring high voltage it's a good idea to hold both probes in the same hand, like chopsticks. In the event of an arc flash you'll only lose a couple of fingers instead of both arms and part of your upper torso.
Also: Sniff the distribution panel before you start. If it smells of ozone then go and get your Fluke. You'll still die but at least people will know that you weren't using a $4 multimeter.
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Those free meters have gone through several hardware changes over the years to reduce cost. Even if we saw a difference between the two meters I show, I couldn't tell you if it had anything to do with the label or not.
Is 1100V the limit? Seems to me like a 2000 count meter should be able to display 2000V... :popcorn:
Looking at my videos, it looks like I stopped at 1100 DC. I ran that UNI-T UT90A to about 1.9kV when I connected it to an electronic flyswatter. If you like, I can try it with the newest free one, my oldest one and that UT90A and just see where they all stop working at. UT90A has had the ass blown out of it so many times, I doubt we would learn anything from it. More just the fun factor.
...
When measuring high voltage it's a good idea to hold both probes in the same hand, like chopsticks. In the event of an arc flash you'll only lose a couple of fingers instead of both arms and part of your upper torso.
...
The friends of mine that who told me about the two arc flash events at work said in the one case, the workers entered the distribution area for maintenance. The area was supposed to have been shut down. Nothing was left of the person nearest the blast. Another worker that was in the area was badly injured but I understand survived. No meters were involved.
The one my friend was involved with where they were trying to make a live measurement, he had enough PPE to save him.
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If you wanted to promote safe practices, mention the one hand rule.
OK. When measuring high voltage it's a good idea to hold both probes in the same hand, like chopsticks. In the event of an arc flash you'll only lose a couple of fingers instead of both arms and part of your upper torso.
Also: Sniff the distribution panel before you start. If it smells of ozone then go and get your Fluke. You'll still die but at least people will know that you weren't using a $4 multimeter.
Hmm… isn’t that rule about not closing the circuit through your heart?
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Deep Dig.
It will always be perplexing to me, the value that is placed on money, the rationality of its worth based solely on what you MIGHT procure with it. You might say it makes the world go 'round, you might say that time is money, but in the end, the intrinsic value can and will ultimately lie within the eye of the beholder.
A sound thought would be, as an EE or aspiring, of the many things to consider, accuracy and safety should inevitably rise to the top.
One could make an equation of such a topic.
Pausing to consider the Essergy, in an attempt to add plausibility or insight to the opinion of the beholder, we still find a negligible array or disqualifying factors, one of the many being Exergy and if you were to consider only the small environmental impacts. We can only conclude that the qualification process has not been 'met' based solely on the factors that an EE or similar should consider when making such a comparison. If you were to factor in safety, manufacturing processes/tolerance/control, accuracy, not to mention the often overlooked "time fooling with this, in a verification aspect", then we can ultimately conclude / make an informed decision.
If you want to add ~$10 to the list of qualifying factors, of the little we find, then I suggest you examine what sort of intrinsic value that Secretary Alexander Hamilton holds in comparison to the aforementioned, after all, it lies within the eye of the beholder.
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Food for thought.
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Accidents happen.
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Regarding safety of "830" meters, I think the most likely effect of a big transient at home is that they'll go "pop" and cease to function
i suspect that you are entirely right. but engineers far more expert on the subject that either of us think otherwise. hence, why we have the various safety standards that exist.
all i am saying is that a piece of gear should EITHER:
a. make no claims, explicit or implicit, that it meets a given level of usability (in this case, to be used to measure AC mains). in the case of a multimeter, this involves removing measurement ranges that fall way outside of the definition of "Extra-Low Voltage": https://en.wikipedia.org/wiki/Extra-low_voltage (https://en.wikipedia.org/wiki/Extra-low_voltage), OR,
b. contain the necessary design elements to comply with the relevant safety standards (in this case, creepage and clearance, component selection and specifications).
i really don't think what i am suggestion is unreasonable.
now, the reality is that "830" meters WILL continue to be made as they always have been, or even more cheaply, and every now and then there will be a serious accident as a result. we live in a global 'free market economy', and things will only change if the market dictates this. that is, the dollar cost of any 'oopsie' moments exceeds the savings in production cost.
as Dave says, "Accidents Happen".
cheers,
rob :-)
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i suspect that you are entirely right. but engineers far more expert on the subject that either of us think otherwise. hence, why we have the various safety standards that exist.
Do you wear steel toecap boots and a hard hat at home? You probably should - just in case! :)
(and wear a condom, too)
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well, as it happens i DO wear steel capped boots all the time! i have done for a great many years, and they have on several occasions saved me from a damaged foot... although it is fun when you walk through a metal detector (such as at the courts) and have to explain why it goes off. i also always carry a small LED torch in my pocket - that a security guard once held up to his own face and turned on.
cheers,
rob :-)
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well, as it happens i DO wear steel capped boots all the time! i have done for a great many years, and they have on several occasions saved me from a damaged foot... although it is fun when you walk through a metal detector (such as at the courts) and have to explain why it goes off. i also always carry a small LED torch in my pocket - that a security guard once held up to his own face and turned on.
OK, that explains your viewpoint... :-DMM
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WTF? :o are they seriously $1.49?
And LOL at the "High Safety".
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This is USD$10 shipped.
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not miles different from the fluke 12B i have, which i use when there isn't a '77 nearby:
(https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1765163)
(see also fluke 7-300 and 7-600)
dave: i don't know about anyone else, but i'd be quite interested in seeing you do a teardown and review of that Aneng M118A meter.
cheers,
rob :-)
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This is USD$10 shipped.
(https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1765149;image)
I've got one of those. I don't like it much - horrible UI and it's impossible to read the text on the buttons without special light.
There's no way in hell I'd trade one for my Big Clive meter.
It also feels nasty and smells bad. The nasty chemical smell from the rubber gets on your hands after a millisecond of handling and you need to wash them afterwards to make it go away.
Edit:
FWIW here's the insides. The big 'chip' is a relay:
(https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1765199;image)
Now I'm off to wash my hands.
PS: Free to good home...
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It also feels nasty and smells bad. The nasty smell from the rubber gets onto your hands after 0.5 seconds and you need to wash your hands after each use.
That's because its made out of recycled Volkswagen's.
edit:
FWIW here's the insides. The big 'chip' is a relay:
Is it a preferred option for your handheld meter to have the board to chassis screw 0.5 -1.0MM (or less, depending on day of the week) from the 600V terminal? I could see how it might be particularly interesting when the screw is long enough that the point of it would reside within 1 or 2 MM from the outside of the unit where you would be presumably be putting an appendage at some point in time. The arc capability of 600V would probably be less then 1.0 MM, quite unimpressive, however it could cause sporadic pontification while in use, which might be of interest.
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... it would reside within 1 or 2 MM from the outside of the unit where you would be presumably be putting an appendage at some point in time.
Is that less than the insulation on a Fluke probe cable?
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Uni-T UT60B is 5.59$ on Aliexpress : https://www.aliexpress.com/item/1005003573433243.html (https://www.aliexpress.com/item/1005003573433243.html)
Bluetooth, temperature measurement (and temperature probe) ... would be interesting to see a review/teardown
There's a Uni-T branded DT-830B meter for almost 8$ ... makes me laugh : https://www.aliexpress.com/item/4001203098253.html (https://www.aliexpress.com/item/4001203098253.html)
But would be interesting to see if it's actually made by Uni-T and if so, what you get for 8$
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Uni-T UT60B is 5.59$ on Aliexpress : https://www.aliexpress.com/item/1005003573433243.html (https://www.aliexpress.com/item/1005003573433243.html)
Bluetooth, temperature measurement (and temperature probe) ... would be interesting to see a review/teardown
Look closer, that's just a clickbait price for just the meter case. The meter itself is 32 Euros
There's a Uni-T branded DT-830B meter for almost 8$ ... makes me laugh
Screenshotted for posterity: :-DD
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Gotta be impressed by Duratool...
Not only can they make a decent DT830 for €3.75, they can also make one with built-in network cable tester for €4.79: :o
(https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1765313;image)
(they managed to keep the transistor tester, too :-+ )
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That's pretty impressive for the price. Initially I thought the cable testing was performed by manually using the probes and checking the continuity by inserting them into the holes. But no - it has LEDs that indicate for you. :clap:
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... it would reside within 1 or 2 MM from the outside of the unit where you would be presumably be putting an appendage at some point in time.
Is that less than the insulation on a Fluke probe cable?
I would guess more.
Perhaps you do not understand the "skin effect" to its full potential. If such is true, then I can elaborate on my short answer to your question.
Its my opinion that it's an insult to include Fluke in the same discussion, and for my reasons, I would direct you to this --> https://www.fluke.com/en/learn/blog/safety/safe-test-tools-real-world-use (https://www.fluke.com/en/learn/blog/safety/safe-test-tools-real-world-use)
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Those free meters have gone through several hardware changes over the years to reduce cost. Even if we saw a difference between the two meters I show, I couldn't tell you if it had anything to do with the label or not.
Is 1100V the limit? Seems to me like a 2000 count meter should be able to display 2000V... :popcorn:
Meter1 is the most recent marked 250V on selector. Note how large print in the back "Do not test voltages over 250 volts".
Meter2 is from when I started running these tests marked 1kV on selector.
Meter3 is the oldest revision I have.
Note how the input has changed over the years to reduce cost. As far as your thoughts on 2000 count meters should all handle 2kV. I guess then the UT61E at 20k counts should handle 20kV and the 300k count GMW should handle 300,000 volts?
Maybe you feel all meters should display a minimum of 2kVDC? Again, I'm not shy about running them. Maybe the 121GW, UT91E, the yellow and the latest at 2kV with the meters set to their highest DCV settings.
***
There were a few people running a similar test using an insulation tester. Of course, it folds back. If we run it, the power supply will have enough power available to not fold back. Are you going to perform the same test with one of your new meters as well?
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from a chart on DigiKey's site (https://www.digikey.co.nz/en/blog/what-are-multimeter-cat-safety-ratings (https://www.digikey.co.nz/en/blog/what-are-multimeter-cat-safety-ratings)) i see:
| Measurement Category | Working Voltage | Transient Voltage | Test Source (Impedance) |
| CAT I | 300 V | 1500 V | 30 Ohms |
| CAT II | 300 V | 2500 V | 12 Ohms |
Joe: roughly, what physical size of resistors would you expect to see at the front end to meet even the 1500v (cat I) requirements? both as a single resistor, and as a string of SMD resistors.
cheers,
rob :-)
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"Wear ANSI approved goggles when replacing the battery"? :-DD
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I have never designed a handheld meter to meet these safety standards and have no idea what is required. Worse, the manufactures don't seem to agree what the requirements are. If that's not bad enough, I question if the "independent" test house monopoly even understands the requirements and will provide unbiased data.
On the plus side, CAT I is a very low energy environment and the risk compared to higher ratings will be lower, assuming the person's education remains constant.
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As far as your thoughts on 2000 count meters should all handle 2kV. I guess then the UT61E at 20k counts should handle 20kV and the 300k count GMW should handle 300,000 volts?
I never said "all meters", or that it was related to counts. It just seemed odd that a 2000 count meter with a 2000V range would stop at 1100V, not 1000V.
If the Uni-T has a 20kV range then it should measure uo to 20kV. I'm betting it doesn't have a range that high though. I'd guess the highest range will be 2kV and it probably displays "OL" if you go past 1kV.
I don't own a Uni-T though or have any gadgets that will generate 1kV-2kV in a controllable manner.
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As far as your thoughts on 2000 count meters should all handle 2kV. I guess then the UT61E at 20k counts should handle 20kV and the 300k count GMW should handle 300,000 volts?
I never said "all meters", or that it was related to counts. It just seemed odd that a 2000 count meter with a 2000V range would stop at 1100V, not 1000V.
Right, you wrote " Seems to me like a 2000 count meter should be able to display 2000V." There was no mention of range until now. Still, on the back of the meter it states "5. Read the manual before use.". You seem to have been missed this as there is no mention of a 2kV range.
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I don't own a Uni-T though or have any gadgets that will generate 1kV-2kV in a controllable manner.
In your case, I wouldn't be too concerned about a particular meter's ability to display or survive to these levels then. Personally, I use a divider rather than attempting to measure voltages outside the range of the meter. Still, I have damaged meters before making such low voltage measurement directly. It's a sinking feeling to watch your expensive Fluke go belly up because of a weak front end design.
Video showing an old and new revision of the DT830 being exposed to 2kV. Double the range of the older and 4X the range of the newest.
https://www.eevblog.com/forum/testgear/hear-kitty-kitty-kitty-nope-not-that-kind-of-cat/msg4829636/#msg4829636 (https://www.eevblog.com/forum/testgear/hear-kitty-kitty-kitty-nope-not-that-kind-of-cat/msg4829636/#msg4829636)
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Right, you wrote " Seems to me like a 2000 count meter should be able to display 2000V." There was no mention of range until now. Still, on the back of the meter it states "5. Read the manual before use.". You seem to have been missed this as there is no mention of a 2kV range.
Right... but then you posted a picture of a "250V" meter happily displaying 1100V:
(https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1762898;image)
I was just wondering where it stops measuring, it seems like a reasonable question to me.
It's a 2000 count meter so 2000V seems like a possible limit.
(unless it freaks out earlier)
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Right, you wrote " Seems to me like a 2000 count meter should be able to display 2000V." There was no mention of range until now. Still, on the back of the meter it states "5. Read the manual before use.". You seem to have been missed this as there is no mention of a 2kV range.
Right... but then you posted a picture of a "250V" meter happily displaying 1100V:
(https://www.eevblog.com/forum/testgear/trashy-meters-redux/?action=dlattach;attach=1762898;image)
I was just wondering where it stops measuring, it seems like a reasonable question to me.
It's a 2000 count meter so 2000V seems like a possible limit.
(unless it freaks out earlier)
These 3 1/2 digit dmms are all based on clones of the Intersil ICL7106, which has been around for decades. The chip basically has a +/-200mV input and display capability which you scale with voltage divider networks for the desired ranges. There is no intelligence in there - there are no dedicated pins for overrange, to enfoce a reading limit etc. The only way to decode the display values going to the display would be a bunch of XOR gates monitoring the LCD segment and backplane drives.
There is no way to limit the display at 250V, it will carry on displaying up to the 2000 digit reading if nothing on the board breaks down first (which it does). The manufacturers have cost reduced the meters to the point where they can't take anything like the maximum display reading without breaking down, and semsibly provided indications on the range switch and warning label. This isn't restricted to 3 1/2 cheapies, many dmms would probably display 2kV, 4kV, or 6kV (depending on IC display counts) but are limited to 1kV on the front panel labelling, instructions, and internal protection / breakdown.
There are two alternatives for the manufacturer. Either delete the 250V range altogether and provide a the maximum range at 200V, or provide the higher range and clearly indicate that it is rated for 250V max (as they have done). I know which alternative most buyers would prefer - and so is what they sell.
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Right, you wrote " Seems to me like a 2000 count meter should be able to display 2000V." There was no mention of range until now. Still, on the back of the meter it states "5. Read the manual before use.". You seem to have been missed this as there is no mention of a 2kV range.
Right... but then you posted a picture of a "250V" meter happily displaying 1100V:
I was just wondering where it stops measuring, it seems like a reasonable question to me.
It's a 2000 count meter so 2000V seems like a possible limit.
(unless it freaks out earlier)
I had posted that picture prior to your asking. The 1100ish volts isn't a magic number. It's where that particular power supply folds back with that load. A different power supply was required to reach the 2kV you had asked about. The counts will have nothing to do with when the hardware fails. All of the meters shown held up beyond their maximum ranges.
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If there is e.g. 1mm PC board spacing (creepage and clearance), question is what (voltage) use are people here comfy with?
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Good testing Joe. The older versions of the M830B-type meters can take a beating but not the newer ones.
Over the years I did several tests on those meters, obviously noting the erosion in quality and materials. However, on my channel I recently tested the Hypertough TD35235J (All-Sun EM830) that is sold at Walmart stores, has third party certification and it is quite well built for the price of $12.99 on US eBay: eBay auction: #294500510119
In my lower voltage tests (up to 280Vac) I was able to damage only the 1.5 and 9V battery testers (I forgot about the load resistors). Overall, it works quite well.
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The counts will have nothing to do with when the hardware fails.
Obviously not. It's more down to the components, the PCB layout, and the dirt inside it.
It might be fun to do a few tests though.
(even if it tells us nothing because every 830 has a different PCB)
All of the meters shown held up beyond their maximum ranges.
This could maybe have been part of your robustness testing - how high will it go on the voltage range before it freaks out?
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If there is e.g. 1mm PC board spacing (creepage and clearance), question is what (voltage) use are people here comfy with?
It's nothing to do with voltage, it's about energy.
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If there is e.g. 1mm PC board spacing (creepage and clearance), question is what (voltage) use are people here comfy with?
It's nothing to do with voltage, it's about energy.
What came first- the voltage creating an electric field causing an insulation breakdown and arc, or the energy behind that arc?
I say creepage and clearance largely determine a multimeter's maximum safe ("before an arc can occur") input voltage. Spacings analysis during certification with UL/CSA, they'll ask for PCB files and go through it. The high voltage tests have the final say.
My point is to look at the DT830 spacings and the astute eye will see some tight spots. Is using this on 240VAC mains outright unsafe? A reasonable question because with a "trashy" meter the risk is good to know. I keep one (DT830) in my car and a friend wants their stove checked. Use it or not?
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If there is e.g. 1mm PC board spacing (creepage and clearance), question is what (voltage) use are people here comfy with?
It's nothing to do with voltage, it's about energy.
What came first- the voltage creating an electric field causing an insulation breakdown and arc, or the energy behind that arc?
That wasn't what you asked, you asked about "comfort".
Is using this on 240VAC mains outright unsafe?
I vote "no".
Proof: The amount of people who use them for that.
I keep one (DT830) in my car and a friend wants their stove checked. Use it or not?
It's as much about procedure as anything else, eg. triple-check the position of the selector and probe wires, give the probe wires a tug before starting, wear wellies, wear a glove on one hand, don't try and measure the amps.
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Is using this on 240VAC mains outright unsafe?
I vote "no".
Proof: The amount of people who use them for that.
[...]
It's as much about procedure as anything else, eg. triple-check the position of the selector and probe wires, give the probe wires a tug before starting, wear wellies, wear a glove on one hand, don't try and measure the amps.
number of people, not amount
regarding the use of the multimeter you happen to have handy rather than the appropriate tool, see:
https://www.ecmweb.com/safety/arc-flash/article/20898038/the-case-of-the-deadly-arc-flash (https://www.ecmweb.com/safety/arc-flash/article/20898038/the-case-of-the-deadly-arc-flash)
cheers,
rob :-)
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Is using this on 240VAC mains outright unsafe?
The phrase I was replying to was "outright unsafe".
I just measured my mains AC using my Big Clive meter. It said 226V and I'm alive to tell the tale. I wasn't even nervous when I did it.
https://www.ecmweb.com/safety/arc-flash/article/20898038/the-case-of-the-deadly-arc-flash (https://www.ecmweb.com/safety/arc-flash/article/20898038/the-case-of-the-deadly-arc-flash)
So ... don't use a DT830 to measure amps on a large industrial 480V supply? Got it! :-+
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Is using this on 240VAC mains outright unsafe?
I vote "no".
Proof: The amount of people who use them for that.
[...]
It's as much about procedure as anything else, eg. triple-check the position of the selector and probe wires, give the probe wires a tug before starting, wear wellies, wear a glove on one hand, don't try and measure the amps.
number of people, not amount
regarding the use of the multimeter you happen to have handy rather than the appropriate tool, see:
https://www.ecmweb.com/safety/arc-flash/article/20898038/the-case-of-the-deadly-arc-flash (https://www.ecmweb.com/safety/arc-flash/article/20898038/the-case-of-the-deadly-arc-flash)
cheers,
rob :-)
The reality of this thread is that nothing anyone can say is gonna convince this guy that his meter is anything short of amazing.
Either we're misrepresenting what he says, or any dangers of the meter can be negated by wearing gumboots, or anyone who doesn't want to risk blowing their hand off to save a few bucks is a softcock, or we don't understand how awesome having a transistor tester in our meter is, or our measurement expectations are too high/low, or you're a 1%er with a bad toupee if you use a proper meter, etc. The goalposts move for every good reason given to avoid a meter that literally costs less than a shitty pizza from Dominos. I've personally been getting a good laugh out of this trainwreck thread ever since the "secret" tip he shared on page one about using hot glue in the ends of your probes to make them better. It's kind of like watching an Ichiban Moto video, except this guy isn't in on the joke.
At the end of the day, old mate just wants a pat on the back for outwitting everyone and getting the bargain of a lifetime.
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Either we're misrepresenting what he says
Yep.
or any dangers of the meter can be negated by wearing gumboots
Why are you banging on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on about "safety".
Not once have I ever said this meter is suitable for high-energy work.
(in fact I've said "don't!" several times)
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Either we're misrepresenting what he says
Yep.
or any dangers of the meter can be negated by wearing gumboots
Why are you banging on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on and on about "safety".
Not once have I ever said this meter is suitable for high-energy work.
(in fact I've said "don't!" several times)
Is using this on 240VAC mains outright unsafe?
The phrase I was replying to was "outright unsafe".
I just measured my mains AC using my Big Clive meter. It said 226V and I'm alive to tell the tale. I wasn't even nervous when I did it.
https://www.ecmweb.com/safety/arc-flash/article/20898038/the-case-of-the-deadly-arc-flash (https://www.ecmweb.com/safety/arc-flash/article/20898038/the-case-of-the-deadly-arc-flash)
So ... don't use a DT830 to measure amps on a large industrial 480V supply? Got it! :-+
Another post, another sidestep. Yawn.
The reason I and others have banged on about safety is because stupid people read stupid advice on the internet and then go do stupid things. This thread is full of such advice. You keep banging on about how these things work just fine at high voltages, then when you get called out you backtrack and claim you never said they were suitable for it. One minute you're saying "Don't do it", the next you're saying you did anyway. Some noob could easily take your bravado as gospel and go probing mains using the wrong terminals or mode and get a free pass to destination fucked. They could even do it correctly, cop a surge and still get that ticket. They could just as easily (and this is the key here) probe something that SHOULD be low energy but isn't due to circuit failure or mislabelling, and be completely unprepared for the shitstorm that rains down.
If you love these things for testing 9V batteries and measuring resistors then cool, that's great. But once you start sprinkling disclaimers about your safety advice being "to appease thread nannies" and telling stories about using these meters for things people shouldn't, you're making a clear inference that these ARE in fact OK to use in potentially lethal situations.
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You keep banging on about how these things work just fine at high voltages, then when you get called out you backtrack and claim you never said they were suitable for it.
Rubbish.
I said they were suitable for high voltage, and I stand by that. Pictures have been posted of a worse meter than this measuring 1100V in somebody's hand.
(I notice you don't go after joe...)
I also said they weren't suitable for high energy. If you can't understand the difference between the two then you're in no position to lecture anybody on safety.
This meter is CAT I 500V rated. I think that's a correct rating and said so in the very first post, anything else is just your imagination.
End of.
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This meter is CAT I 500V rated. I think that's a correct rating
i see that Fungus lives in country "00". it is a wonderful land, where if you just print "Cat I" onto a product, you are absolved from any and all responsibility. if someone burns off their hand, you are not responsible. if an explosion kills two people - the person holding the multimeter and a fireman standing next to him - then no worries, the "Cat I" label is completely and absolutely 100% flame and explosion proof, at least for the person who prints it onto the product. it also protects against legal liability and... most importantly, moral responsibility.
i feel that we should all move to country "00". it is a great place from which to offer our opinions.
cheers,
rob :-)
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Agree, CAT I like most of us work with, the concern I have with the meters is if they survive. I have no problem connecting any meter to the low energy sources I typically encounter. Of course, normally I don't use them outside of their maximum ratings. Still, shit happens and I have damaged my fair share of meters. Which is why I ran these tests to get a feel for how robust the various brands are. These tests have been conducted at low energy levels as I have never been concerned with safety.
All of the meters shown held up beyond their maximum ranges.
This could maybe have been part of your robustness testing - how high will it go on the voltage range before it freaks out?
I don't normally connect a meter to a steady state source that is outside of it's rated limit. Even at low currents the meter can be damaged. I suspect there more than one fool watched one of my videos and saw me apply several kV to the same meter they owned and thought, hey, Joe shows my meter passed at 8kV so it should be fine to measure my 2kV MOT. :-DD I've received dumb comments accusing me of connecting them directly to a capacitor bank or a DC source. The worse are when they equate what I show to some sort of safety test.
The most recent was a youtuber who claimed to work in education where they are involved with a EE program. It's rare I will take the time to hunt someone down but in this case I made an exception. Sure enough, they did not embellish their statements. As fast as they pulled their comments after posting a link on this site, I assume they are a member. :-DD
As far as the testing, I have seen what I was looking for. Even with these low energy transients, chemical exposures and mechanical wear test, there is certainly a difference between brands.
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The "CAT I" marking is IMHO somewhat confusing and doesn't necessarily mean much in terms of overvoltage/transient protection.
The long story: there is the concept of "overvoltage categories" (defined for example in IEC 60664-1) which are essentially a classification that helps you to figure out necessary clearances, creepages etc. depending on overvoltages/transients that would be expected to occur in a circuit.
Those are related to, but not the same as, "measurement categories" which are supposed to tell the user of a measurement instrument whether it is safe to use it on a particular mains-connected circuit ("CAT ratings"). In particular, "overvoltage category I" is actually defined in terms of concrete impulse withstand voltages (e.g. 1.5 kV for a 300V supply mentioned above) while CAT I is not. IEC 61010-1 used to give concrete values for CAT II and higher and acknowledged that CAT I (not directly mains-connected) could cover a lot of different scenarios and the need for overvoltage protection would need to be determined (and documented) depending on the application.
Nowadays, the definition of the measurement categories has been moved to IEC 61010-2-030 and -033 and there is now only CAT II, III and IV as well as "equipment without a rated measurement category" (used to be CAT I). I suspect that the designation CAT I was removed because it was found to be confusing/inconsistent.
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I'm curious--how many people here have actually plugged something into the mains that did not survive and which exploded as a result? My impression is that although the bang and the flash can be quite exciting, the main danger is likely to be flying shrapnel hitting your eyes, and therefore the most useful item of PPE would be safety glasses. I don't recall much mention of that in this thread, but if we were to offer useful safety advice to readers then I think the use of eye protection would be at the top of the list.
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I'm curious--how many people here have actually plugged something into the mains that did not survive and which exploded as a result?
:-DD :-DD :-DD :-DD
Are you actually expecting the spirit of Billy Bob Ray to channel through one of the members here?
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...
Nowadays, the definition of the measurement categories has been moved to IEC 61010-2-030 and -033 and there is now only CAT II, III and IV as well as "equipment without a rated measurement category" (used to be CAT I). I suspect that the designation CAT I was removed because it was found to be confusing/inconsistent.
I don't believe that's something new. Even in EVS-EN 61010-2-033:2012 it was replaced with O: Other circuits that are not directly connected to MAINS
, but I continue to see papers published that refer to CAT I.
Fluke's application note: ABCs of multimeter safety Multimeter safety and you
for example states:
CAT I Electronic • Protected electronic equipment
• Equipment connected to (source) circuits in which measures
are taken to limit transient overvoltages to an appropriately
low level
• Any high-voltage, low-energy source derived from a highwinding
resistance transformer, such as the high-voltage
section of a copier
With different countries all having their own twist on these standards (I assume to leverage for import export) the may not use the same definitions.
If I were repairing toasters, I wouldn't be too concerned. Even in the previous post, the fact they were mentioning plugging into mains tells me something.
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My impression is that although the bang and the flash can be quite exciting, the main danger is likely to be flying shrapnel hitting your eyes, and therefore the most useful item of PPE would be safety glasses.
The bang and flash could easily make you fall off a ladder. Or make you step backwards and put your foot in the bucket.
I don't recall much mention of that in this thread
You never will. The nannies assume that simply owning a yellow meter is sufficient protection. No gumboots needed.
I continue to see papers published that refer to CAT I.
It's a useful designation. The "other" category still needs a name.
Roman numerals don't have zeros so maybe they could have renamed it "CAT X".
I suspect that the designation CAT I was removed because it was found to be confusing/inconsistent.
Me? I'd have picked CAT II as the "useless" category.
a) A single piece of wire can be CAT II at one end and CAT III at the other. It doesn't get much more "confusing/inconsistent" than that. :scared:
b) Is there a real job where you only ever work at CAT II level and never at CAT III?
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...
Nowadays, the definition of the measurement categories has been moved to IEC 61010-2-030 and -033 and there is now only CAT II, III and IV as well as "equipment without a rated measurement category" (used to be CAT I). I suspect that the designation CAT I was removed because it was found to be confusing/inconsistent.
I don't believe that's something new. Even in EVS-EN 61010-2-033:2012 it was replaced with O: Other circuits that are not directly connected to MAINS
, but I continue to see papers published that refer to CAT I.
Yes, I just checked and DIN-EN 61010-1:2002 defines "measurement category I" (while 2010 does not). IEC 61010-2-033 didn't even exist back then, multimeters were covered by the general norm. I feel old now.
It's certainly true that it has stuck around. You even get new products with "CAT I" markings, even though AFAIK you were never really supposed to do that even back then (terminals with measurement category I are supposed to be labelled with the voltage rating, only the higher categories should have "CAT x" printed next to them).
What I hope people take away from this:
- CAT II, III, IV have very specific meanings in terms of overvoltage protection
- "CAT I" just means "not supposed to be connected directly to a mains circuit"; there may or may not be additional protection beyond the rated voltage, check the manual
If someone decides not to follow safety standards that is fine by me (as long as they do not endanger anyone else). I just think that this should be a conscious decision, not a result of ignorance or misinformation.
Me? I'd have picked CAT II as the "useless" category.
a) A single piece of wire can be CAT II at one end and CAT III at the other. It doesn't get much more "confusing/inconsistent" than that. :scared:
b) Is there a real job where you only ever work at CAT II level and never at CAT III?
a) The difference between CAT II - IV circuits is basically all wiring (which adds impedance) and usually a fuse or circuit breaker somewhere between each level.
Anyway, the level of protection for CAT II is clearly defined and it means the same on any meter, whether you find it useful or not. The problem with CAT I was that is just says "could mean anything, read the manual".
b) Yes, anyone repairing or developing mains-powered electronics or appliances will usually need CAT II only (CAT III is for electricians).
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You keep banging on about how these things work just fine at high voltages, then when you get called out you backtrack and claim you never said they were suitable for it.
Rubbish.
I said they were suitable for high voltage, and I stand by that. Pictures have been posted of a worse meter than this measuring 1100V in somebody's hand.
(I notice you don't go after joe...)
I also said they weren't suitable for high energy. If you can't understand the difference between the two then you're in no position to lecture anybody on safety.
This meter is CAT I 500V rated. I think that's a correct rating and said so in the very first post, anything else is just your imagination.
End of.
Right, because Joe clearly knows what he's talking about and also clearly knows the difference between safety based on knowledge and safety based on wilful ignorance.
Again, you're playing word games with voltage/energy as if there's no relation. A high voltage/low energy circuit can become a lethally high energy circuit pretty damn quickly under all sorts of fault or user error conditions. A correctly set meter being tested under controlled conditions with a sample size you can count on one hand is not an endorsement of a meter being suitable for use at high voltage.
Do what you want in your own time, but if you're gonna carry on on the internet about a poorly constructed hobbyist meter being suitable for high voltages be prepared for disagreement.
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I feel old now.
You and me both!
What I hope people take away from this:
- CAT II, III, IV have very specific meanings in terms of overvoltage protection
As a general observation, meters that have been certified to the 61326 EMC standards do well against my tests. The protection is a dice roll as what it even means. Protect the meter, protect the operator, both... Manufactures don't agree. I was interested in finding meters that would not be damaged when subjected to a few basic transients. It doesn't really fit with the IEC standards and why I rolled my own generator. I wanted something like the 6100-4-5 surge but limited. So I dropped the combo, followed the open circuit voltage waveforms, ignored the short circuit current and limited it to about 20J. Depending on the generator, I used a 50 or 100us FWHH and stayed with a 2 ohms source across the board.
We did have a member how stepped up and ran a new Fluke 101 on a real combo generator after I tested that first one. Crazy how robust these things are. That was Fungus's contribution as I would have never purchased another Fluke otherwise as I was still pissed at them a few decades later for designing such a weak meter (8000A). :-DD
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I feel old now.
You and me both!
What I hope people take away from this:
- CAT II, III, IV have very specific meanings in terms of overvoltage protection
As a general observation, meters that have been certified to the 61326 EMC standards do well against my tests. The protection is a dice roll as what it even means. Protect the meter, protect the operator, both... Manufactures don't agree. I was interested in finding meters that would not be damaged when subjected to a few basic transients. It doesn't really fit with the IEC standards and why I rolled my own generator. I wanted something like the 6100-4-5 surge but limited. So I dropped the combo, followed the open circuit voltage waveforms, ignored the short circuit current and limited it to about 20J. Depending on the generator, I used a 50 or 100us FWHH and stayed with a 2 ohms source across the board.
We did have a member how stepped up and ran a new Fluke 101 on a real combo generator after I tested that first one. Crazy how robust these things are. That was Fungus's contribution as I would have never purchased another Fluke otherwise as I was still pissed at them a few decades later for designing such a weak meter (8000A). :-DD
Have you got any plans to torture test any bench meters? Unless I missed it I haven't seen any so far from you. I'd be really curious to see what you find
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b) Yes, anyone repairing or developing mains-powered electronics or appliances will usually need CAT II only (CAT III is for electricians).
OK, let's say I'm working on a PC power supplies in a large office building. How can I know for sure if the mains on my workbench is CAT II or CAT III? Am I supposed to trace the wires in the walls back to the distribution panel and measure how long they are before deciding what meter to use? That's the only way to follow the standard.
Let's suppose it's a company with a few different rooms with workbenches. Will all those rooms have the same CAT rating?
Should a professional or a company like that even make the effort to source/purchase CAT II meters? What would be the advantage? What brand/model would you advise them to buy?
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Have you got any plans to torture test any bench meters? Unless I missed it I haven't seen any so far from you. I'd be really curious to see what you find
Are bench meters supposed to be robust? In my mind I think of them as sensitive, delicate, precision instruments, things to be treated with care. Would you expect an expensive Mitutoyo micrometer to survive being chucked in a tool drawer?
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b) Yes, anyone repairing or developing mains-powered electronics or appliances will usually need CAT II only (CAT III is for electricians).
OK, let's say I'm working on a PC power supplies in a large office building. How can I know for sure if the mains on my workbench is CAT II or CAT III? Am I supposed to trace the wires in the walls back to the distribution panel and measure how long they are before deciding what meter to use? That's the only way to follow the standard.
Let's suppose it's a company with a few different rooms with workbenches. Will all those rooms have the same CAT rating?
Should a professional or a company like that even make the effort to source/purchase CAT II meters? What would be the advantage? What brand/model would you advise them to buy?
Sounds identical to the grumbling in another recent low cost multimeter thread: https://www.eevblog.com/forum/testgear/aneng-sz20-25-000-count-1uv-10na-20a/ (https://www.eevblog.com/forum/testgear/aneng-sz20-25-000-count-1uv-10na-20a/)
Is it plugged into a mains socket outlet, but lacks at least 1 form of isolation? You're in CAT II land.
Someone else has done the hard work and figured out the probability of seeing something outside of CAT II at a mains outlet is vanishingly improbable (assuming everything upstream of there is installed to your prevailing standards). Broad categories that encompass close to worst case conditions.
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BTW, the DT830 meter was designed by Li Hong in 1984, the founder of Zotek, as per my recent video.
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Someone else has done the hard work and figured out the probability of seeing something outside of CAT II at a mains outlet is vanishingly improbable (assuming everything upstream of there is installed to your prevailing standards). Broad categories that encompass close to worst case conditions.
Yes, but:
a) You can't tell if it's a CAT II mains socket just by looking at it so what meter should you use?
b) Is there any point in buying a meter for mains work that's limited to CAT II? (eg. Is it much cheaper? What...?)
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a) You can't tell if it's a CAT II mains socket just by looking at it so what meter should you use?
b) Is there any point in buying a meter for mains work that's limited to CAT II? (eg. Is it much cheaper? What...?)
what on earth has this got to do with the discussion of a meter marked "Cat I"?!
the argument over the difference between "Cat II" and "Cat III" designation is a sideshow, please start a new thread about it.
cheers,
rob :-)
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the argument over the difference between "Cat II" and "Cat III" is a sideshow, please start a new thread about it.
Not a bad idea.
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Someone else has done the hard work and figured out the probability of seeing something outside of CAT II at a mains outlet is vanishingly improbable (assuming everything upstream of there is installed to your prevailing standards). Broad categories that encompass close to worst case conditions.
Yes, but:
a) You can't tell if it's a CAT II mains socket just by looking at it so what meter should you use?
b) Is there any point in buying a meter for mains work that's limited to CAT II? (eg. Is it much cheaper? What...?)
Every mains socket outlet is CAT III, things plugged into it are CAT II until they reach safety isolation at which point the electronics beyond there can become CAT I. Why is this so hard to understand?
(https://www.eevblog.com/forum/testgear/aneng-sz20-25-000-count-1uv-10na-20a/?action=dlattach;attach=1758098;image)
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Have you got any plans to torture test any bench meters? Unless I missed it I haven't seen any so far from you. I'd be really curious to see what you find
Are bench meters supposed to be robust? In my mind I think of them as sensitive, delicate, precision instruments, things to be treated with care. Would you expect an expensive Mitutoyo micrometer to survive being chucked in a tool drawer?
Are you talking about drop tests etc? I'm talking about surges/spikes/overload conditions/etc
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Edit: Discussion forked to Here: https://www.eevblog.com/forum/testgear/is-cat-ii-a-useful-rating/ (https://www.eevblog.com/forum/testgear/is-cat-ii-a-useful-rating/)
You can't tell if it's a CAT II mains socket just by looking at it so what meter should you use?
Every mains socket outlet is CAT III
Fluke's notes (https://www.fluke.com/en/learn/blog/safety/multimeter-guide) say:
CAT III:
Appliance outlets with short connections to service entrance
CAT II:
Outlets at more than 10 meters (30 feet) from CAT III source.
Outlets at more than 20 meters (60 feet) from CAT IV source.
I think it's a good idea to assume that a socket is CAT III when dealing with it, so that rules out CAT II multimeters.
things plugged into it are CAT II
You're saying the difference between CAT III and CAT II is an extra 1m of cable?
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b) Yes, anyone repairing or developing mains-powered electronics or appliances will usually need CAT II only (CAT III is for electricians).
OK, let's say I'm working on a PC power supplies in a large office building. How can I know for sure if the mains on my workbench is CAT II or CAT III? Am I supposed to trace the wires in the walls back to the distribution panel and measure how long they are before deciding what meter to use? That's the only way to follow the standard.
The fact that it's a standard mains outlet on bench pretty much puts it in the CAT II range.
Anything in a fuse box or plant room is CAT III at least, maybe CAT IV
Fluke have a handy guide.
Let's suppose it's a company with a few different rooms with workbenches. Will all those rooms have the same CAT rating?
Could technically depend on the distance, but a CAT III meter covers everything outside of a direct utility connection./
Should a professional or a company like that even make the effort to source/purchase CAT II meters? What would be the advantage? What brand/model would you advise them to buy?
If you work on anything mains, get CAT III minimum as a basic rule.
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It can be instructive to look at the breakers in the consumer unit / breaker panel in non-industrial settings. Standard IEC61009-1 breakers normally have a maximum breaking capacity of 6kA. It is the responsibility of the installing electricial to measure and ensure that the Zin is high enough and and the PSC low enough to fall within the limits of these breakers. In the case of my installation, the Zin is 0.12R, equating to a PSC of 2kA [Edit @240V], people often overestimate the prospective fault currents on their domestic installations, I've seen wild estimates in some threads. This does not cover short duration network induced voltage spikes of course, which are too fast to trip the breakers.
A competent electricial, in either industrial or consumer settings will ensure that they know such figures for the installation and ensure that their test equipment ratings exceed the prospective fault currents involved.
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Have you got any plans to torture test any bench meters? Unless I missed it I haven't seen any so far from you. I'd be really curious to see what you find
Are bench meters supposed to be robust? In my mind I think of them as sensitive, delicate, precision instruments, things to be treated with care. Would you expect an expensive Mitutoyo micrometer to survive being chucked in a tool drawer?
I don't think I've ever seen a bench meter that is CAT III/IV rated, it's just not a thing.
e.g.
(https://asset.conrad.com/media10/isa/160267/c1/-/en/1372637_BB_00_FB/image.jpg)
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things plugged into it are CAT II
You're saying the difference between CAT III and CAT II is an extra 1m of cable?
FFS, the division between the categories has to be placed somewhere. Do you want to colour code your cabling and outlets to indicate their voltages and fault currents? and make everyone else in the world do the same? or perhaps introduce 43 new categories so you can define the difference between 1.2m and 1.8m supply leads?
There are 4 categories, each with really simple and easy to remember delineations, the almost worst case situation for each is what the measurement device needs to withstand. Keeps it to a manageable number of certifications/specifications and simplifies worldwide compliance.
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FFS, the division between the categories has to be placed somewhere.
Either that or ... eliminated?
Just switch everything to "CAT III", job done.
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I'm brushing up on these CAT ratings because I haven't thought about it for a while, and because I think I'll try to explain them to some of the local hams who don't know what it all means (I can practically guarantee that).
I get the divisions between them, but I can't find what they define as a "transient". Is there a definition for "transient" as pertains to the CAT ratings? Yes the transient is a voltage spike bit for how long?
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Every mains socket outlet is CAT III, ...
Provide a reference in any of the IEC standards from any country that states that.
Have you got any plans to torture test any bench meters? Unless I missed it I haven't seen any so far from you. I'd be really curious to see what you find
While I understand the responses about the bench meters and CAT ratings, I assume you are asking from the standpoint of how robust they are and not about safety. It's certainly a valid thought. My first Fluke was the perfect example of how not to design a robust meter. I damaged it more than once with very low level transients. When looking for something to replace it, I spoke with a friend who worked at HP. They use GDTs and other clamps on the front end to protect the sensitive circuits. I bought two different ones new and never looked back. In all the years I have owned the HP34401A, the only time it was damaged was during a lightning storm where we took a hit. I made a video of my repairs.
I haven't looked at new bench meters in a long time. The few I have would have cost far more than the Gossen Ultra I looked at. I have an old Fluke 8506 that would have been over $10k new, back when it was made. You could spend $100k in a shootout. The high costs would mean turning to advertising and other funding. This isn't something I have considered.
When running these benchmarks, one of the common feedbacks received was from people who saw no value in the testing and see it as a waste of money. I appreciate that they were concerned about my personal finances but you can imagine the whining when you start to burn down more than someone makes in a year in one video. :-DD
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Well the way I was teached some years ago regarding the CAT rankings were the following:
CAT l - Electronics (<= 48V);
CAT II - Single Phase outlets and connected equipments;
CAT III - Three-phase distribution and connected equipments;
CAT lV - Three-phase at utility connection (meter head), any outdoor conductors (buried or not).
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Are bench meters supposed to be robust? In my mind I think of them as sensitive, delicate, precision instruments, things to be treated with care. Would you expect an expensive Mitutoyo micrometer to survive being chucked in a tool drawer?
Are you talking about drop tests etc? I'm talking about surges/spikes/overload conditions/etc
I'm making an analogy. A sensitive mechanical instrument should be treated with mechanical care. Similarly, a sensitive electrical instrument should be treated with electrical care.
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Every mains socket outlet is CAT III, ...
Provide a reference in any of the IEC standards from any country that states that.
I quoted the AS61010 standard in the other thread that this has split into. Not having any of the international examples to hand at the moment that will do, and you're free to provide quotes from others.
61010 measurement categories are really simple:
"CAT III is for measurements performed in the building installation"
Good luck trying to argue that a mains socket affixed to the wall is something other than the building installation. But we have several people trying to be "clever" and say either side of the socket outlet should be treated the same, when the standard says that is the point of distinction.
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Well the way I was teached some years ago regarding the CAT rankings were the following:
CAT l - Electronics (<= 48V);
CAT II - Single Phase outlets and connected equipments;
CAT III - Three-phase distribution and connected equipments;
CAT lV - Three-phase at utility connection (meter head), any outdoor conductors (buried or not).
Well, you were taught incorrectly. Phase count is irrelevant, and CAT I is far more specific than a voltage limit.
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FFS, the division between the categories has to be placed somewhere.
Either that or ... eliminated?
Just switch everything to "CAT III", job done.
Yeah, I don't know why anyone would be pedantic over the exact delineation. If you are working on anything mains related, get at least a certified 600V CAT III meter. It's not like they are expensive. The Fluke 101/113, almost any Brymen, and there are plenty of other options in higher feature capability meters.
Industrial plant techs should consider using a 600V CAT IV meter.
If you are using a CAT II only meter then you don't really care about mains or CAT rating, it's just a multimeter.
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Every mains socket outlet is CAT III, ...
Provide a reference in any of the IEC standards from any country that states that.
Have you got any plans to torture test any bench meters? Unless I missed it I haven't seen any so far from you. I'd be really curious to see what you find
While I understand the responses about the bench meters and CAT ratings, I assume you are asking from the standpoint of how robust they are and not about safety. It's certainly a valid thought. My first Fluke was the perfect example of how not to design a robust meter. I damaged it more than once with very low level transients. When looking for something to replace it, I spoke with a friend who worked at HP. They use GDTs and other clamps on the front end to protect the sensitive circuits. I bought two different ones new and never looked back. In all the years I have owned the HP34401A, the only time it was damaged was during a lightning storm where we took a hit. I made a video of my repairs.
I haven't looked at new bench meters in a long time. The few I have would have cost far more than the Gossen Ultra I looked at. I have an old Fluke 8506 that would have been over $10k new, back when it was made. You could spend $100k in a shootout. The high costs would mean turning to advertising and other funding. This isn't something I have considered.
When running these benchmarks, one of the common feedbacks received was from people who saw no value in the testing and see it as a waste of money. I appreciate that they were concerned about my personal finances but you can imagine the whining when you start to burn down more than someone makes in a year in one video. :-DD
Exactly, my question was kind of a sidenote (I probably should have just PM'd it in retrospect). I figured the insane cost was probably one of the main stumbling blocks, haha. But yeah- my curiosity was definitely about how the input stages of various models might cope when things go wrong. Which really circles back to the cost thing as well- for the price of some of those things it'd be great to know how well protected (or not) various models are.
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Are bench meters supposed to be robust? In my mind I think of them as sensitive, delicate, precision instruments, things to be treated with care. Would you expect an expensive Mitutoyo micrometer to survive being chucked in a tool drawer?
Are you talking about drop tests etc? I'm talking about surges/spikes/overload conditions/etc
I'm making an analogy. A sensitive mechanical instrument should be treated with mechanical care. Similarly, a sensitive electrical instrument should be treated with electrical care.
You're kind of making the same mistaken assumption as the OP here that everything is always controllable- it's not. Devices fail while under test, surges happen, test points can be mislabeled, probing mistakes happen, etc.
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I'm making an analogy. A sensitive mechanical instrument should be treated with mechanical care. Similarly, a sensitive electrical instrument should be treated with electrical care.
You're kind of making the same mistaken assumption as the OP here that everything is always controllable- it's not. Devices fail while under test, surges happen, test points can be mislabeled, probing mistakes happen, etc.
There's no mistaken assumption here. If you drop your expensive micrometer on the concrete floor and put it out of alignment, that's tough on you, time to buy a new one. Similarly, if you blow up your expensive bench meter by accident, that is similarly tough on you. Time to replace it or get it repaired. What you don't do is get the probes from that expensive meter and recklessly stick them in unknown circuits. If you do that you have only yourself to blame for mishaps.
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Every mains socket outlet is CAT III, ...
Provide a reference in any of the IEC standards from any country that states that.
I quoted the AS61010 standard in the other thread that this has split into. Not having any of the international examples to hand at the moment that will do, and you're free to provide quotes from others.
61010 measurement categories are really simple:
"CAT III is for measurements performed in the building installation"
Good luck trying to argue that a mains socket affixed to the wall is something other than the building installation. But we have several people trying to be "clever" and say either side of the socket outlet should be treated the same, when the standard says that is the point of distinction.
My home has a tiny little service coming into from a small distribution transformer. Nothing like what feeds for the buildings where I worked. Outlets at my house are several feet from the main feed and are behind small CBs which are behind another small one. Worse thing that will happen if I pull an outlet and short the wires, I blow a CB. Hardly CAT III or risk of an arc flash.
Even at work where we have larger services to plug into, it's a long way from the main lines and again fed though various CBs. Lots to limit the current. Some of the larger factories I have worked will have their own distribution systems outside in fenced areas.
I'm not going to get all concerned about my home toaster repairs and my CAT III outlets because it's just not the same thing. If I have to go into the field, I have equipment for that.
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Exactly, my question was kind of a sidenote (I probably should have just PM'd it in retrospect). I figured the insane cost was probably one of the main stumbling blocks, haha. But yeah- my curiosity was definitely about how the input stages of various models might cope when things go wrong. Which really circles back to the cost thing as well- for the price of some of those things it'd be great to know how well protected (or not) various models are.
The robustness of bench meters is effectively stamped on the front. Both of mine (Keithly and Keysight) are CAT II 300V. That screams "I'm delicate please don't hurt me!"
No need for testing, just assume all bench meters are delicate snowflakes.
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Some of my bench meters:
GW Instek GDM-8251A
CAT I 1000V
CAT II 600V
Rigol DM3058E
CAT II 600V
Others such as hp 34401a and older bench meters don't specifically state CAT on the front panel (but may in the manual I haven't looked yet).
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The robustness of bench meters is effectively stamped on the front. Both of mine (Keithly and Keysight) are CAT II 300V. That screams "I'm delicate please don't hurt me!"
No need for testing, just assume all bench meters are delicate snowflakes.
Or test them to a common standard and see how they shake out which is what David is asking about. No big deal to benchmark them.
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Every mains socket outlet is CAT III, ...
Provide a reference in any of the IEC standards from any country that states that.
I quoted the AS61010 standard in the other thread that this has split into. Not having any of the international examples to hand at the moment that will do, and you're free to provide quotes from others.
61010 measurement categories are really simple:
"CAT III is for measurements performed in the building installation"
Good luck trying to argue that a mains socket affixed to the wall is something other than the building installation. But we have several people trying to be "clever" and say either side of the socket outlet should be treated the same, when the standard says that is the point of distinction.
My home has a tiny little service coming into with a small distribution transformer. Nothing like the feeds for the buildings where I worked. Outlets at my house are several feet from the main feed and are behind small CBs which is behind another small one. Worse thing that will happen if I pull and outlet and short the wires, I blow a breaker. Hardly CAT III or risk of an arc flash.
Even at work where we have larger services to plug into, it's a long way from the main lines and again fed though various CBs. Lots to limit the current. Some of the larger factories I have worked will have their own distribution systems outside in fenced areas.
I'm not going to get all concerned about my home toaster repairs and my CAT III outlets because it's just not the same thing.
So what's the supply impedance at those socket outlets? Because over here we do see impedances at the outlets low enough in residential installations to require >1kA breaking capacity in a meter hence the need for at least CAT II for mains connected devices. I've not worked on or measured a high current residential supply with lower impedances, but with electrification of vehicles they will become more common and then you're into the CAT III fault currents (100A 2% droop) before considering transients/faults.
Yes, it may well be that there is no need for the higher ratings of CAT III somewhere (or anywhere) between the socket outlet and the supply feeder in your installation, that will vary from location to location. I'm not disagreeing with that but the standards have to cover a huge range of possible situations and almost (but not guaranteed) worst cases so most real world examples will be far below the limits. The standard is a way to have a quickly and easily understood delineation point, which you and others are going to great lengths to try and muddy/blur/confuse for some unknown reason.
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I have a small question for everyone in this thread: do your lightbulbs have a CAT rating on them? When you twist a bulb into its socket, do you ever worry about it exploding in your hand? Do you wear safety glasses and rubber shoes when you change a lightbulb?
A DMM may be connected to the mains for a few seconds at a time to take a reading, and there is only one of them. All the lamps in your house are connected to the mains 24/7 and switched on for hours at a time. They could explode, cause a fire, or cause human injury. The risk is vastly higher than with using a DMM.
Why are there many threads about meters, and no threads about household appliances and electrical devices? There are millions more of the latter, and a proportionately higher hazard, statistically.
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Why are there many threads about meters, and no threads about household appliances and electrical devices? There are millions more of the latter, and a proportionately higher hazard, statistically.
Because engineers like to nitpick about test equipment.
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The robustness of bench meters is effectively stamped on the front. Both of mine (Keithly and Keysight) are CAT II 300V. That screams "I'm delicate please don't hurt me!"
No need for testing, just assume all bench meters are delicate snowflakes.
Or test them to a common standard and see how they shake out which is what David is asking about. No big deal to benchmark them.
Sure, but I'd bet few people would care. It's not like you'd use that as a buying decision for a 4 digit priced bench meter.
And if you thought there are a lot of people complaining about blowing up DMM's is pointless, wait until you blow up expensive high end bench meters.
But hey, knock yourself out.
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I have a small question for everyone in this thread: do your lightbulbs have a CAT rating on them? When you twist a bulb into its socket, do you ever worry about it exploding in your hand? Do you wear safety glasses and rubber shoes when you change a lightbulb?
A DMM may be connected to the mains for a few seconds at a time to take a reading, and there is only one of them. All the lamps in your house are connected to the mains 24/7 and switched on for hours at a time. They could explode, cause a fire, or cause human injury. The risk is vastly higher than with using a DMM.
I wouldn't change a light bulb unless the switch is turned off, no I don't tag out or prove the circuit de-energised but that works 99.999% of the time (yes I have been shocked from that approach and faulty power switch). Equally I wouldn't put my face near a lamp when powering it on for the first time, proximity to a handheld multimeter is generally very different.
Electrical fires in appliances/cabling, yep that happens more often.
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I have a small question for everyone in this thread: do your lightbulbs have a CAT rating on them? When you twist a bulb into its socket, do you ever worry about it exploding in your hand? Do you wear safety glasses and rubber shoes when you change a lightbulb?
A DMM may be connected to the mains for a few seconds at a time to take a reading, and there is only one of them. All the lamps in your house are connected to the mains 24/7 and switched on for hours at a time. They could explode, cause a fire, or cause human injury. The risk is vastly higher than with using a DMM.
Why are there many threads about meters, and no threads about household appliances and electrical devices? There are millions more of the latter, and a proportionately higher hazard, statistically.
Appliances have a legal path to a manufacturer, whereas many chinese multimeters have none. Appliances, "electrical devices", light bulbs have lots of room for HV spacings. Small handheld multimeters have no room for reasonable clearances and sized fuses. They are used generally close to your face and hands with exposed wires.
The issue is cheap chinese multimeters with fake/spoofed safety claims and zero evidence of any testing.
They need to stop this horseshit. It just fuels threads like this spinning around the requirements amidst unknown capabilities of the product. Because they can and do involve measurements needing some trust of the numbers- yet they command zero trust for safety, having no evidence of testing or any formal vouching.
We know SFA about the DT830's abilities or design, and there are dozens of variants.
A simple question about suitability for measuring 240VAC mains is a guessing game. People soon will be using these on electric cars and she'll be right.
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Why are there many threads about meters, and no threads about household appliances and electrical devices? There are millions more of the latter, and a proportionately higher hazard, statistically.
There's also similar lack of discussion about wearing gloves+gumboots and going outside to look at the sky before you use your multimeter on mains.
It just never comes up. :-//
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My home has a tiny little service coming into from a small distribution transformer. Nothing like what feeds for the buildings where I worked. Outlets at my house are several feet from the main feed and are behind small CBs which are behind another small one. Worse thing that will happen if I pull an outlet and short the wires, I blow a CB. Hardly CAT III or risk of an arc flash.
Same here. That's why I wasn't worried about measuring the mains with my Big Clive special.
Knowledge is power.
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Well, you were taught incorrectly.
Don't be too hard on him. Even Fluke corporation is confused by these 'standards' (https://www.eevblog.com/forum/testgear/is-cat-ii-a-useful-rating/msg4833239/#msg4833239).
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And if you thought there are a lot of people complaining about blowing up DMM's is pointless, wait until you blow up expensive high end bench meters.
I think joe secretly enjoys the complaints. 8)
you can imagine the whining when you start to burn down more than someone makes in a year in one video. :-DD
Maybe you could be the whistlindiesel (https://www.youtube.com/@whistlindiesel/videos) of the test gear world.
Go big or go home... :popcorn:
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My home has a tiny little service coming into from a small distribution transformer. Nothing like what feeds for the buildings where I worked. Outlets at my house are several feet from the main feed and are behind small CBs which are behind another small one. Worse thing that will happen if I pull an outlet and short the wires, I blow a CB. Hardly CAT III or risk of an arc flash.
Same here. That's why I wasn't worried about measuring the mains with my Big Clive special.
Knowledge is power.
Ignorance is bliss. Like a chinese fortune cookie, "May your multimeter's spacings be auspicious".
I think so far it's magical opinion and unicorns telling us the DT830 is OK at x volts. Or we can argue it's the requirements at fault - the IEC overvoltage categories are wrong. Not that the product has ever been tested or evaluated to meet its fake claims.
Strange for EE's to discard science for a cheap "trashy" cause.
"Hardly CAT III" you'd need to run a Dranetz (https://www.dranetz.com/) to convert speculation and gut feel to fact. I've used loggers in facilities to see if power is a problem with equipment failures. Like making a measurement with some test equipment :-DD
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I think so far it's magical opinion and unicorns telling us the DT830 is OK at x volts.
I never said "DT830".
The Big Clive special is a "D03047" - it says so right there in the title.
"DT830" covers a million variants so I could never make a blanket statement like that.
Not that the product has ever been tested or evaluated to meet its fake claims.
What fake claims are those? "CAT I"??
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Maybe you could be the whistlindiesel (https://www.youtube.com/@whistlindiesel/videos) of the test gear world.
I might do it if there was a crowd funder for it.
I doubt any company would give one for nix to be specifically overload tested.
Ok, I draw the line HERE
https://www.youtube.com/watch?v=vWwReT83Zto (https://www.youtube.com/watch?v=vWwReT83Zto)
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Maybe you could be the whistlindiesel (https://www.youtube.com/@whistlindiesel/videos) of the test gear world.
I might do it if there was a crowd funder for it.
I'm not sure that's how it works.
Maybe you could start by running over some working Fluke 8060As in your car.
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Using DMMs on the mains is somewhat overrated (no pun intended). In a lot of cases it rather akin to beginners getting their first fancy scope, having nothing to look at other than the cal output, and being hypnotically drawn to the nearest mains outlet.
Most use cases are establishing whether mains is present or not, rather than measuring its voltage to within a few volts. Electricians use proper 2-pole testers for such purposes, together with a simple proving unit. These are inevitably at least 600V Cat III. The cheaper professional ones have a basic LED bargraph voltage display, the slightly more expensive ones, an LCD voltage readout too. They normally have a basic continuity and phase rotation tests too, with the same Cat rating. No finger-trouble controls, captive probe lead, and they still give a live voltage indication even if the batteries are flat or missing.
Decent qualtity second hand 2-pole testers can be picked up quite cheaply on ebay (Don't go to Ali!). When you get one, you should carry out the inspections detailed in the manual - check for cracks, lead damage, tug test etc. And verify that they indicate correctly. Proper safe isolation procedure requires indication verification before and after checking the circuit of interest. That's where the battery powered proving unit comes in. You can get those on ebay too, but it's easy enough to make your own with a simple self oscillating inverter - this is pefectly safe to do, if you don't get a reading on the proving unit then any test on the mains circuit is automatically invalid.
Most measurement tests involve a safely isolated, dead circuit. Once the circuit is proven dead and preferably locked off with a clip on the breaker, you can perform resistance measurements etc. Proper second hand insulation and continuity testers (again with the comfort of Cat rating), are again easily available on ebay. They will probably be past their calibration date, but are very easy to verify with a bunch of low and high value resistors and a Cat 1 1kV DMM.
The only other live tests are beyond the capabilities of a DMM anyway. Ze / PSC (prospective fault current) tests require a dedicated tester as does RCD trip current / trip time. RCD testers are also pretty cheaply available too (again they may be past cal, but if an RCD trips at 1 x In and holds at 0.5 x In then it is good enough. RCDs have test buttons anyway.
In summary, there is very little reason to be using a DMM on a live mains circuit.
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"Hardly CAT III" you'd need to run a Dranetz (https://www.dranetz.com/) to convert speculation and gut feel to fact. I've used loggers in facilities to see if power is a problem with equipment failures. Like making a measurement with some test equipment :-DD
Several years ago I had Dranetz come in for a visit to demonstrate their latest products. After the sales demos, I started to ask about their testing. After all the point is we would be using it to capture various events. Normally companies will leave the products for a few weeks to get a feel if they are fit for the job. So I asked them about subjecting it to the various safety standards. They had no problem with this, so I invited them to attend. We all had a fun time that day.
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I think so far it's magical opinion and unicorns telling us the DT830 is OK at x volts.
I never said "DT830".
The Big Clive special is a "D03047" - it says so right there in the title.
"DT830" covers a million variants so I could never make a blanket statement like that.
Not that the product has ever been tested or evaluated to meet its fake claims.
What fake claims are those? "CAT I"??
Sadly, I suspect they missed the whole point of these measurements with the free DT830 meter were on a CAT1 low energy circuit. I would have thought that when I stated that the one power supplies current limit kicked in with the input impedance of the meter, something would have clicked.
I'm not going to get all concerned about my home toaster repairs and my CAT III outlets because it's just not the same thing.
So what's the supply impedance at those socket outlets?
I'll try and make a few measurements today with my tiny home wires. I assume you will do the same so we have something to compare. If not, I can measure some larger circuits.
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The robustness of bench meters is effectively stamped on the front. Both of mine (Keithly and Keysight) are CAT II 300V. That screams "I'm delicate please don't hurt me!"
No need for testing, just assume all bench meters are delicate snowflakes.
Or test them to a common standard and see how they shake out which is what David is asking about. No big deal to benchmark them.
Sure, but I'd bet few people would care. It's not like you'd use that as a buying decision for a 4 digit priced bench meter.
And if you thought there are a lot of people complaining about blowing up DMM's is pointless, wait until you blow up expensive high end bench meters.
But hey, knock yourself out.
David Aurora had asked me so I responded. No big deal. I do agree that there are few people in the world who are interested in electronics. Guessing your point is few people would watch but that's true of all my videos. :-DD
I have a friend who owns a motorcycle speed shop and was talking with them about their business. They made the point of suggesting to go for a drive and count the number of cars vs bikes. Now take that small percentage of bike and ask how many of them race. Then how many of that small segment drag. Not many of us but we have fun.
As I mentioned, I did ask about robustness of the HP meters before buying them. It's the only test equipment that I would care about due to it being used to measure several hundred volts (not to mention the small transients it can get exposed to). It's not like my other equipment that is limited to a < 50V with warnings of ESD damage everywhere.
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I'm not going to get all concerned about my home toaster repairs and my CAT III outlets because it's just not the same thing.
So what's the supply impedance at those socket outlets?
I'll try and make a few measurements today with my tiny home wires. I assume you will do the same so we have something to compare. If not, I can measure some larger circuits.
[/quote]
I assume because we are talking commercial vs industrial, you want to keep this below 250V? Are you wanting any other metrics or just the impedance for the three legs?
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The robustness of bench meters is effectively stamped on the front. Both of mine (Keithly and Keysight) are CAT II 300V. That screams "I'm delicate please don't hurt me!"
No need for testing, just assume all bench meters are delicate snowflakes.
Or test them to a common standard and see how they shake out which is what David is asking about. No big deal to benchmark them.
Sure, but I'd bet few people would care. It's not like you'd use that as a buying decision for a 4 digit priced bench meter.
And if you thought there are a lot of people complaining about blowing up DMM's is pointless, wait until you blow up expensive high end bench meters.
But hey, knock yourself out.
Not primarily, of course. But if you're scratching your head between models that stack up very similarly (as many meters do), and one is shown to be better built than the other, that's a no brainer. At that price point they're all going to agree on a 9 volt battery or a 10k resistor, so build quality or even little things like display visibility/control layout/fan noise etc start to dominate (for me, anyway). Teardowns are one way of comparing build quality, stress testing is another.
Also, I should clarify (although Joe clearly gets it) that I'm not saying let's try to set fire to top notch instruments and destroy them just for a laugh. I'm saying I'd like to see how different models cope under stress. Same as most other meter tests- can they tolerate a decent voltage when in wrong modes? What happens if you exceed the max voltage or current ratings, does the protection work properly or does damage occur? What happens if there's a spike on the input? What happens if the meters own supply voltage drops during measurements (e.g. during a brown out)? What happens if you flick between front/rear terminals during high voltage/current measurements? And so on.
I think the price of these things is all the more reason to do stringent testing rather than just rubber stamping them because of the price, brand or accuracy. People run these tests and more before declaring a $20 meter good or bad, why not a $5000 meter?
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Some meters have a multi-gigaohm input impedance, and while I don't know how this is implemented, I would guess the input more or less is going directly to the gate of an FET? If that is the case, is there any way these can have robust input protection?
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I'm making an analogy. A sensitive mechanical instrument should be treated with mechanical care. Similarly, a sensitive electrical instrument should be treated with electrical care.
You're kind of making the same mistaken assumption as the OP here that everything is always controllable- it's not. Devices fail while under test, surges happen, test points can be mislabeled, probing mistakes happen, etc.
There's no mistaken assumption here. If you drop your expensive micrometer on the concrete floor and put it out of alignment, that's tough on you, time to buy a new one. Similarly, if you blow up your expensive bench meter by accident, that is similarly tough on you. Time to replace it or get it repaired. What you don't do is get the probes from that expensive meter and recklessly stick them in unknown circuits. If you do that you have only yourself to blame for mishaps.
If you're only ever sticking your probes in circuits you know back to front, that are well documented and are guaranteed to be behaving correctly I've got to assume you're unemployed. Jesus Christ. From one day to another all sorts of shit lands on my bench for inspection, often already worked on by cowboys or DIYers. Just the last few disasters that spring to mind are a power switch where a terminal had somehow internally shorted to the actuator, a tube amp where some numb nuts had wired the 450V B+ directly to the input jack, missing insulation between transistors and heatsinks, incorrectly connected transformers... the list goes on. Surprises happen and sometimes your probes find something you weren't expecting, welcome to the real world.
I have a small question for everyone in this thread: do your lightbulbs have a CAT rating on them? When you twist a bulb into its socket, do you ever worry about it exploding in your hand? Do you wear safety glasses and rubber shoes when you change a lightbulb?
A DMM may be connected to the mains for a few seconds at a time to take a reading, and there is only one of them. All the lamps in your house are connected to the mains 24/7 and switched on for hours at a time. They could explode, cause a fire, or cause human injury. The risk is vastly higher than with using a DMM.
Why are there many threads about meters, and no threads about household appliances and electrical devices? There are millions more of the latter, and a proportionately higher hazard, statistically.
I turn the switch off before changing them, because I'm not a fucking idiot. To each their own though I guess :-//
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I am curious if there are any auto mechanics on this forum? EV battery voltage can be as high as 800V. And, the energy stored is significant. What does this group (auto mechanics) do about using instruments safely?
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I turn the switch off before changing them, because I'm not a fucking idiot. To each their own though I guess :-//
What if it's a two (or three) way switch and you don't know if it's on or off? Do you rewire your house first?
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I turn the switch off before changing them, because I'm not a fucking idiot. To each their own though I guess :-//
What if it's a two (or three) way switch and you don't know if it's on or off? Do you rewire your house first?
The neon screwdriver would come out of that drawer in the kitchen that has the non-cooking items such as string, Stanley knife, spare keys, candles, fuse wire, tap washers etc.
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The neon screwdriver would come out of that drawer in the kitchen that has the non-cooking items such as string, Stanley knife, spare keys, candles, fuse wire, tap washers etc.
You forgot the rubber bands and batteries ;D
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The neon screwdriver would come out of that drawer in the kitchen
Make sure it's a certified CAT III screwdriver, not a fake Chinese one
(https://ringelectric.ca/wp-content/uploads/2017/07/Professional-Electrician.png)
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Some meters have a multi-gigaohm input impedance, and while I don't know how this is implemented, I would guess the input more or less is going directly to the gate of an FET? If that is the case, is there any way these can have robust input protection?
In the case of the Datrons that I'm familiar with, there's a 100k 10W resistor chain before the bootstrapped protection diode (well, JFETS and Zeners) network on the Hi-Z input ranges. I'm not as familiar with other brands.
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I have a small question for everyone in this thread: do your lightbulbs have a CAT rating on them? When you twist a bulb into its socket, do you ever worry about it exploding in your hand? Do you wear safety glasses and rubber shoes when you change a lightbulb?
I realize that this is a rhetorical question but the thread seems to have gone sideways anyway. So, here is a fun fact: a lightbulb ("self-ballasted LED lamp for general lighting services by voltage above 50 V") has to be tested to a withstand voltage of 4 * nominal line voltage + 2000 Vrms between the contacts and any accessible parts for 1 minute in an environment with >91% humidty. Around here that works out to roughly 4kV peak.
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Using DMMs on the mains is somewhat overrated (no pun intended). In a lot of cases it rather akin to beginners getting their first fancy scope, having nothing to look at other than the cal output, and being hypnotically drawn to the nearest mains outlet.
Most use cases are establishing whether mains is present or not, rather than measuring its voltage to within a few volts. Electricians use proper 2-pole testers for such purposes, together with a simple proving unit. These are inevitably at least 600V Cat III. The cheaper professional ones have a basic LED bargraph voltage display, the slightly more expensive ones, an LCD voltage readout too. They normally have a basic continuity and phase rotation tests too, with the same Cat rating. No finger-trouble controls, captive probe lead, and they still give a live voltage indication even if the batteries are flat or missing.
Decent qualtity second hand 2-pole testers can be picked up quite cheaply on ebay (Don't go to Ali!). When you get one, you should carry out the inspections detailed in the manual - check for cracks, lead damage, tug test etc. And verify that they indicate correctly. Proper safe isolation procedure requires indication verification before and after checking the circuit of interest. That's where the battery powered proving unit comes in. You can get those on ebay too, but it's easy enough to make your own with a simple self oscillating inverter - this is pefectly safe to do, if you don't get a reading on the proving unit then any test on the mains circuit is automatically invalid.
Most measurement tests involve a safely isolated, dead circuit. Once the circuit is proven dead and preferably locked off with a clip on the breaker, you can perform resistance measurements etc. Proper second hand insulation and continuity testers (again with the comfort of Cat rating), are again easily available on ebay. They will probably be past their calibration date, but are very easy to verify with a bunch of low and high value resistors and a Cat 1 1kV DMM.
The only other live tests are beyond the capabilities of a DMM anyway. Ze / PSC (prospective fault current) tests require a dedicated tester as does RCD trip current / trip time. RCD testers are also pretty cheaply available too (again they may be past cal, but if an RCD trips at 1 x In and holds at 0.5 x In then it is good enough. RCDs have test buttons anyway.
In summary, there is very little reason to be using a DMM on a live mains circuit.
Ah, the good old days... sadly, my Fluke T5-1000 uses 2x AA (rechargeables work fine, which I prefer even though I can get free industrial Duracells at work), as do many two-probe testers these days.
In point of fact, a DMM does have a place in the electrician's toolbag. The continuity test that a pair of Steinels or an installation tester can do has a maximum of a few hundred ohms, the insulation tester function can only measure by using 250V or more, at 1mA, which is death for many things you might find connected to your fixed wiring.
A real case scenario for this happened a few weeks back, when we were trying to track down an earth fault on a fire alarm. The insulation tester I had brought had a maximum resistance reading of 200kΩ, before the insulation test ranges. The installation tester had continuity only. The earth fault, as it turns out, (I took my F87V in the next day...) was around 360kΩ, so we couldn't see it with any of the testers (it wasn't possible to remove all the fire alarm devices on a section, and naturally enough, that was the offending section) at the first attempt. Still, we got a full weekend of overtime out of it, so no complaints...
Also, though I don't get to play with UPS's at work these days, you definitely need a DMM for that, also if you're playing with VFD's, and almost all PLC /automated machinery.
One of the electricians that joined us recently has a bloody neon screwdriver; I keep threatening to throw it in a skip if he leaves it unattended. If he wields it anywhere near a DB or panel board, I will rugby tackle him to the floor and smash that piece of shit with a club hammer.
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One of the electricians that joined us recently has a bloody neon screwdriver; I keep threatening to throw it in a skip if he leaves it unattended. If he wields it anywhere near a DB or panel board, I will rugby tackle him to the floor and smash that piece of shit with a club hammer.[/color][/font][/b]
Do it! It's your H&S duty as well as being fun. >:D
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I think so far it's magical opinion and unicorns telling us the DT830 is OK at x volts.
I never said "DT830".
The Big Clive special is a "D03047" - it says so right there in the title.
"DT830" covers a million variants so I could never make a blanket statement like that.
Not that the product has ever been tested or evaluated to meet its fake claims.
What fake claims are those? "CAT I"??
Post #1 (https://www.eevblog.com/forum/testgear/trashy-meters-redux/msg4808471/#msg4808471) the input jack board markings "830B.2XB", main board "832.2" so I see it as a DT832. "DT" for Duratool? KT logo maybe Ketai. They go for less than USD $1.50 ea. in bulk :o
With the fake "EN 61010 Cat. I 500V label" Interesting on Alibaba (https://www.alibaba.com/trade/search?fsb=y&IndexArea=product_en&CatId=&tab=all&SearchText=dt832&selectedTab=product_en) 99% of DT830B, DT832 etc. show a "61010" or "Cat. x" label. Farnell is getting some extra. Others majority of them jacks say 500VAC "Cat. I 250V" or others 750VAC/1,000VDC Max. which I could believe if there is proof of test.
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give me a trusty test lamp any day over a digital /led testers,no battery's to go flat and they draw enough current to avoid weird ghost readings
bloody neon screwdriver;
bit of silver paper from a fag packet across the resistor soon makes the owner chuck em away
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Post #1 (https://www.eevblog.com/forum/testgear/trashy-meters-redux/msg4808471/#msg4808471) the input jack board markings "830B.2XB", main board "832.2" so I see it as a DT832. "DT" for Duratool? KT logo maybe Ketai. They go for less than USD $1.50 ea. in bulk :o
With the fake "EN 61010 Cat. I 500V label" Interesting on Alibaba (https://www.alibaba.com/trade/search?fsb=y&IndexArea=product_en&CatId=&tab=all&SearchText=dt832&selectedTab=product_en) 99% of DT830B, DT832 etc. show a "61010" or "Cat. x" label. Farnell is getting some extra. Others majority of them jacks say 500VAC "Cat. I 250V" or others 750VAC/1,000VDC Max. which I could believe if there is proof of test.
"DURATOOL is the registered trademark of Premier Farnell Limited"
I think it's safe to assume that they had it tested if they sell it under their brand. It is possible that they have requested some minor changes to make it pass. (Reputable EU sellers used to have their own version of some Uni-T meters with better fuses and different ratings printed on them so they would actually pass safety testing and be able to sell them legally.)
Like I said above, in this case "CAT I" almost certainly means "no overvoltage protection" (the manual, probably written by Farnell, carefully specifies "overload protection" for all modes, none of which exceeds 500V). So "CAT I 500V" is really not a very high bar. The difference in terms of clearances and insulation is something like 5x-10x compared to CAT II (aka "delicate snowflakes").
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I thought a ripoff of Duratool Taiwan.
Cat. I 300V is a 1,500V impulse, Cat. I 600V 2,500V and there is no "500V" mains category.
Cat. II 300V spacings is 1.5mm. If the multimeter's PC board layout was done professionally, that isn't hard to achieve. But this multimeter again shows a clown car for the traces, this is why without a spacings analysis or formal testing, it's a bit scary.
EE's strive to do good but occasionally fail and this is why testing is done.
Let's see Premier Farnell provide a test certificate of any kind. That should be a good laugh.
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Cat. I 300V is a 1,500V impulse, Cat. I 600V 2,500V and there is no "500V" mains category.
That would be "overvoltage category I", not "measurement category I" which used to be defined in IEC 61010-1. The latter just means that the measured circuit is "not directly connected to mains". The necessary overvoltages ratings are supposed to be application-dependent and are supposed to be documented by the manufacturer.
EDIT: "There are no standard transient levels defined for these circuits. An analysis of the WORKING VOLTAGES, loop impedances, TEMPORARY OVERVOLTAGES, and TRANSIENT OVERVOLTAGES in these circuits is necessary to determine the insulation requirements and short-circuit current requirements."
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Duratool D03047 multimeter, suitable for mains measurements or not? :popcorn:
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Well, assuming the CAT I label is not fake, so long as your mains is "not directly connected to mains", you should be fine. :horse:
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My home has a tiny little service coming into with a small distribution transformer. Nothing like the feeds for the buildings where I worked. Outlets at my house are several feet from the main feed and are behind small CBs which is behind another small one. Worse thing that will happen if I pull and outlet and short the wires, I blow a breaker. Hardly CAT III or risk of an arc flash.
So what's the supply impedance at those socket outlets?
I'll try and make a few measurements today with my tiny home wires. I assume you will do the same so we have something to compare. If not, I can measure some larger circuits.
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I assume because we are talking commercial vs industrial, you want to keep this below 250V? Are you wanting any other metrics or just the impedance for the three legs?
I'm out of that work these days so don't have the instrumentation to hand. It would be very interesting to see just how high impedance can get on your "wimpy" installation. (over here the target end to end is less than 5% droop so there is an upper ceiling).
But as this keeps coming back to the same point, it will be possible to find all sorts of installations that will have prospective fault currents and robust voltage filtering/complex impedances that they could well be safely measured with a lower category meter. That is entirely expected since the standards have to cover worst case installations.
The "argument" is back to front, if people want to claim the category ratings are excessively strict then it is on them to show every installation meets their new criteria, on the other side I only need to show/find a single example at the limits to demonstrate they are sensible (quickly shown by the current capacity of residential feeds and GPO circuits with their associated maximum droop).
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Duratool D03047 multimeter, suitable for mains measurements or not?
If you plugged that into mains power in Australia and something went wrong, it would be on you since the meter is not rated for that. That's going to be the same in most "developed" countries.
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I turn the switch off before changing them, because I'm not a fucking idiot. To each their own though I guess :-//
What if it's a two (or three) way switch and you don't know if it's on or off? Do you rewire your house first?
If it was really a safety concern (which it's not, but I'll play along and pretend we're talking about a broken bulb where you need to grab the base or something) I'd flip the breaker or grab a chicken stick. I'm guessing this is the bit where you remind us you're a hero and you'd do it with your teeth because you're super tough and cool and physics don't apply to you?
Just to recap- THIS is the argument for why that meter is suitable for high voltage work? Because people change light bulbs? Cooooool.
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My home has a tiny little service coming into with a small distribution transformer. Nothing like the feeds for the buildings where I worked. Outlets at my house are several feet from the main feed and are behind small CBs which is behind another small one. Worse thing that will happen if I pull and outlet and short the wires, I blow a breaker. Hardly CAT III or risk of an arc flash.
So what's the supply impedance at those socket outlets?
I'll try and make a few measurements today with my tiny home wires. I assume you will do the same so we have something to compare. If not, I can measure some larger circuits.
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I assume because we are talking commercial vs industrial, you want to keep this below 250V? Are you wanting any other metrics or just the impedance for the three legs?
I'm out of that work these days so don't have the instrumentation to hand. It would be very interesting to see just how high impedance can get on your "wimpy" installation. (over here the target end to end is less than 5% droop so there is an upper ceiling).
But as this keeps coming back to the same point, it will be possible to find all sorts of installations that will have prospective fault currents and robust voltage filtering/complex impedances that they could well be safely measured with a lower category meter. That is entirely expected since the standards have to cover worst case installations.
The "argument" is back to front, if people want to claim the category ratings are excessively strict then it is on them to show every installation meets their new criteria, on the other side I only need to show/find a single example at the limits to demonstrate they are sensible (quickly shown by the current capacity of residential feeds and GPO circuits with their associated maximum droop).
Home lab is two floors away and diagonally opposite of the feed. Testing my distribution block at 20A, the drop is about 11.2%. ASCC is about 0.25kA line to neutral. As I said wimpy and hardly anything that concerns me.
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If I skip the AC strip I normally use and go directly to one of the outlets I measure a voltage drop of 6.3% at 12A. Hot is 0.38 ohms, neutral 0.20 ohms and ground is 0.04 ohms. ASCC is 0.26kA. Scary stuff.
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I have an outlet I use for my small MIG welder that on the same floor and much closer to the feed point. 4.5% drop at 12A. 7.3% at 20A. Hot is 0.31 ohms, neutral is 0.1 ohms and ground is 0.04 ohms. ASCC for this outlet measures 0.39kA.
The house has mostly tiny little 14AWG wire. With all the concern I am guessing Australia uses 0000 AWG to wire their homes.
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Tried an outlet at work for the fun of it ASCC was 1.96kA. A little better but still hardly a concern. We don't have arc flash signs on every outlet. Maybe that's code in Australia for all residential outlets.
I have been at factories that had to plan ahead with the power company before switching loads. It's a different world than my home.
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I turn the switch off before changing them, because I'm not a fucking idiot. To each their own though I guess :-//
What if it's a two (or three) way switch and you don't know if it's on or off? Do you rewire your house first?
If it was really a safety concern (which it's not, but I'll play along and pretend we're talking about a broken bulb where you need to grab the base or something) I'd flip the breaker or grab a chicken stick. I'm guessing this is the bit where you remind us you're a hero and you'd do it with your teeth because you're super tough and cool and physics don't apply to you?
Just to recap- THIS is the argument for why that meter is suitable for high voltage work? Because people change light bulbs? Cooooool.
I just screw in the new one with it live. Then again, with these new LEDs, it's rare.
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I turn the switch off before changing them, because I'm not a fucking idiot. To each their own though I guess :-//
What if it's a two (or three) way switch and you don't know if it's on or off? Do you rewire your house first?
If it was really a safety concern (which it's not, but I'll play along and pretend we're talking about a broken bulb where you need to grab the base or something) I'd flip the breaker or grab a chicken stick. I'm guessing this is the bit where you remind us you're a hero and you'd do it with your teeth because you're super tough and cool and physics don't apply to you?
Just to recap- THIS is the argument for why that meter is suitable for high voltage work? Because people change light bulbs? Cooooool.
I just screw in the new one with it live. Then again, with these new LEDs, it's rare.
Yeah, anyone with half a brain can replace a bulb without killing themselves, I was just indulging their point by trying to find a situation where it might actually be a problem :-//
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If I skip the AC strip I normally use and go directly to one of the outlets I measure a voltage drop of 6.3% at 12A. Hot is 0.38 ohms, neutral 0.20 ohms and ground is 0.04 ohms. ASCC is 0.26kA. Scary stuff.
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Tried an outlet at work for the fun of it ASCC was 1.96kA. A little better but still hardly a concern. We don't have arc flash signs on every outlet. Maybe that's code in Australia for all residential outlets.
:-+ >1kA is fairly common here on residential GPOs but it's kept simple so there are no special warnings or differentiation, people treat all outlets as equivalently dangerous (just like 61010). Would I measure any of those examples with a meter containing unbranded/unknown 20x5mm fuses? nope.
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I have no reason to measure my line voltage. I can just look at the lights and see if they are dim. If I want to look at some sort of device hanging on the line, I tossed together a simple box with a transformer and current sense so the equipment is isolated.
I use these cheap meters on the bench and while I may frequently run experiments in excess of a kV, it's hardly a concern. When I benchmark the meters, while the generator's outputs are not directly connected to the mains (for safety), the small one is still 20J. Not the most safe thing to play with but I have a fair bit of safety designed into the system. The scary one in the half cycle simulator as we are now around 600J. Photonic Induction would call me a chicken but I use a chicken stick any time I use that thing and keep the outputs shorted when not in use. I consider it CAT1 but by no means that that suggest it is safe to play with.
I've shown various loads including meters, fuses and light bulbs attached to that generator. Hardly any concern about an arc flash at 600J. It will cause a light bulb to shatter.
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Why are there many threads about meters, and no threads about household appliances and electrical devices? There are millions more of the latter, and a proportionately higher hazard, statistically.
I think I mentioned I had to repair our microwave a while back. Turned out the fuse had popped. Sent the wife out to pick up a new one and when I get home, I get the story of how the parts store wouldn't sell the fuse to her. The told her they wouldn't sell any parts for the microwave because of the hazards. People die playing service man with them.
Wife begins to tell them that she had watched me pull trip the CB before opening it. Then how I showed her all the bits and how I made a few comments about the design and why things were laid out the way they were for safety. Then she tells them about this long stick I had used to touch some things inside before I did anything inside. They said your good, and sold her the fuse. :-DD I can't blame them.
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I love this story, Joe. My wife would probably be able to tell the same details, although the trick is in the convincing and assuring tone... :-DD
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My home has a tiny little service coming into from a small distribution transformer. Nothing like what feeds for the buildings where I worked. Outlets at my house are several feet from the main feed and are behind small CBs which are behind another small one. Worse thing that will happen if I pull an outlet and short the wires, I blow a CB. Hardly CAT III or risk of an arc flash.
Same here. That's why I wasn't worried about measuring the mains with my Big Clive special.
Knowledge is power.
Ignorance is bliss. Like a chinese fortune cookie, "May your multimeter's spacings be auspicious".
I think so far it's magical opinion and unicorns telling us the DT830 is OK at x volts. Or we can argue it's the requirements at fault - the IEC overvoltage categories are wrong. Not that the product has ever been tested or evaluated to meet its fake claims.
Strange for EE's to discard science for a cheap "trashy" cause.
"Hardly CAT III" you'd need to run a Dranetz (https://www.dranetz.com/) to convert speculation and gut feel to fact. I've used loggers in facilities to see if power is a problem with equipment failures. Like making a measurement with some test equipment :-DD
It's not something I would normally care about but with member Someone asking, I provided ASCC measurements for my home at a few locations which included my office. Sadly, Someone did not have the basic tools to make the measurements they were asking about. I thought it was odd that anyone with keen interest in mains safety wouldn't have some basic tools available at least to measure in CAT II. Maybe you do and can make a few measurements in your own home that we can use as a comparison.
I want to be clear that those measurements have nothing to do with the high voltage experiment I ran with the two DT830s. Those power supplies will have far less energy available than my small transient generator. And as I said, the DT830 presented enough of a load on the one that the current folded back and we could only reach 1.1kV. So that's 1.1kV/1Meg or 1.1mA. Is that's scary stuff for a meter? Depends on the energy available. Basically, I am referring to the output filter on these supplies. If I placed some large, low ESR capacitors directly across the supplies output and let them charge up before attaching the meter. As soon as I connect the meter, the current is no longer limited to 1.1mA. The energy is 1/2 CV^2. So a 33uF cap would provide around 20 Joules. I posted a link the the DOE safety guidelines and I'm sure all the safety minded folks like yourself understand there is some risk working with even 20J. Will it explode a hand held meter, hardly. Could it kill you, sure. Does what I show have anything to do with AC mains measurements or safety standards, not at all.
Let's see your data.
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I love this story, Joe. My wife would probably be able to tell the same details, although the trick is in the convincing and assuring tone... :-DD
:-DD I'm sure if you put your wife and mine in a room, they would have similar stories to swap.
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It's not something I would normally care about but with member Someone asking, I provided ASCC measurements for my home at a few locations which included my office. Sadly, Someone did not have the basic tools to make the measurements they were asking about. I thought it was odd that anyone with keen interest in mains safety wouldn't have some basic tools available at least to measure in CAT II. Maybe you do and can make a few measurements in your own home that we can use as a comparison.
To clarify, did you make these measurements by putting a load on the circuit and measuring the drop in voltage?
I think there would be an interesting difference here between countries. In the USA I commonly observe a voltage drop when loads are applied, for example the lights dim when a clothes iron or laser printer cycles on and off, or even when a neighbor's aircon unit starts up. I think everyone is probably familiar with this.
In the UK, I have observed no such effects. The electrical supply is often very stiff, such that the the first time I was in the USA and observed lights dimming I was quite surprised. Some reasons for this might include that in Britain the distribution transformer is commonly a large pad mounted unit that supplies a whole block of houses, therefore it will have a consequently low output impedance. Secondly, the distribution cabling under the street is correspondingly large, since it has to carry enough current for all the houses connected to it. Thirdly, in most houses the power circuits are rated to carry 32 A, even though individual outlets are limited to 13 A. Any UK electricians here can probably give an estimate of the typical short circuit current available in such an installation.
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In the UK, I have observed no such effects.
In the UK they use a ring main system so there's probably less impedance to the sockets than your average USA installation.
https://en.wikipedia.org/wiki/Ring_circuit
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It's not something I would normally care about but with member Someone asking, I provided ASCC measurements for my home at a few locations which included my office. Sadly, Someone did not have the basic tools to make the measurements they were asking about. I thought it was odd that anyone with keen interest in mains safety wouldn't have some basic tools available at least to measure in CAT II. Maybe you do and can make a few measurements in your own home that we can use as a comparison.
To clarify, did you make these measurements by putting a load on the circuit and measuring the drop in voltage?
Yes. I'm not sure how else these instruments would work. With mine, I can program the load. I provided that detail in the post.
I think there would be an interesting difference here between countries. In the USA I commonly observe a voltage drop when loads are applied, for example the lights dim when a clothes iron or laser printer cycles on and off, or even when a neighbor's aircon unit starts up. I think everyone is probably familiar with this.
I am not sure how many homes are fed from a transformer here. It's not the entire block. Maybe five homes. Mains are underground and transformers are on slabs.
Transformers are tiny as you would expect. There is a main feed line for these transformers. I believe then each home is fed as a star.
I have not seen (light bulbs do provide a simple, sensitive detector) any transients from the neighbors. In the house, the A/C, sump, clothes drier, oven and stove would be the largest loads but I don't see any effects from them. Even back when we were using incandescents. The problem here is that the grid is not stable.
In the UK, I have observed no such effects. The electrical supply is often very stiff, such that the the first time I was in the USA and observed lights dimming I was quite surprised. Some reasons for this might include that in Britain the distribution transformer is commonly a large pad mounted unit that supplies a whole block of houses, therefore it will have a consequently low output impedance. Secondly, the distribution cabling under the street is correspondingly large, since it has to carry enough current for all the houses connected to it. Thirdly, in most houses the power circuits are rated to carry 32 A, even though individual outlets are limited to 13 A. Any UK electricians here can probably give an estimate of the typical short circuit current available in such an installation.
I assume its all considered magical opinion and unicorns unless measured. :-DD While nothing to do with my kV DT830 demonstration, I wouldn't mine seeing what the people who are concerned, measure themselves, in their own homes.
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In the UK, I have observed no such effects.
In the UK they use a ring main system so there's probably less impedance to the sockets than your average USA installation.
https://en.wikipedia.org/wiki/Ring_circuit
It's becoming increasingly common to use radials instead of rings. It's annoying for me because it's a lot harder to get two 4mm2 T+E into a back-box than two 2.5mm2, especially given the ever decreasing space available as they shrink containment down to save money >:(
Even worse when you have to pull it into conduit! :rant:
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I assume its all considered magical opinion and unicorns unless measured. :-DD While nothing to do with my kV DT830 demonstration, I wouldn't mine seeing what the people who are concerned, measure themselves, in their own homes.
Fair enough. Which is why I would curious if any UK based electricians here could indicate what kind of prospective fault current would be measured at a typical UK 13 A wall socket? (It would be a range, obviously, but typical/min/max would be interesting.)
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Fair enough. Which is why I would curious if any UK based electricians here could indicate what kind of prospective fault current would be measured at a typical UK 13 A wall socket? (It would be a range, obviously, but typical/min/max would be interesting.)
Wikipedia says (https://en.wikipedia.org/wiki/Ring_circuit#Description) typical UK ring circuits have 30A fuses and 2.5mm2 cable.
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Seems like it would be fairly common information and easy to find but my search was a bust. I did come across this site for the electrical workers. Mostly seems related to industrial environment.
https://forums.mikeholt.com/threads/available-fault-current-approximation.2568479/ (https://forums.mikeholt.com/threads/available-fault-current-approximation.2568479/)
https://forums.mikeholt.com/threads/ascc.60843/ (https://forums.mikeholt.com/threads/ascc.60843/)
https://forums.mikeholt.com/threads/voltage-drop.25793/ (https://forums.mikeholt.com/threads/voltage-drop.25793/)
https://forums.mikeholt.com/threads/nec-240-86-series-ratings.15668/ (https://forums.mikeholt.com/threads/nec-240-86-series-ratings.15668/)
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Article on testers
https://www.workingre.com/electrical-receptacle-testers-demystified/ (https://www.workingre.com/electrical-receptacle-testers-demystified/)
Audio buffs are concerned with it.. The sound of a top of the line audio system would certainly be degraded if plugged into my lab's outlets.
https://www.youtube.com/watch?v=4qCK--lRFd0&t=1s (https://www.youtube.com/watch?v=4qCK--lRFd0&t=1s)
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All UK mains plugs are required to have BS1362 fuses (https://en.wikipedia.org/wiki/BS_1363#Fuses_(BS_1362)) in them, and the biggest fuse is 13A.
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Sadly, Someone did not have the basic tools to make the measurements they were asking about. I thought it was odd that anyone with keen interest in mains safety wouldn't have some basic tools available at least to measure in CAT II.
Really? Plenty of CAT III meters here, but I dont not have either:
mains impedance measuring tool (as to measure the earth and lines individually)
or
some significant and benign load (such as a resistive heater or load bank) to do a simpler line-neutral measurement
Sure that second item might be somewhat common, but the first is specialist, and I wouldn't call either route "basic". We know the ceiling to impedances here because Australian installations are required to maintain a maximum droop under their full load.
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Really.
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Really.
As I said, I have worked in electrical trades in the past. Employers had need for various test equipment that I used in industrial commercial and residential settings. Currently do not have the equipment to measure fault currents (safely or accurately) or even a mains current clamp....
Is the maths or reference to standards I present somehow questionable because of the lack of current equipment that I personally own? Is the personal equipment I own related to my knowledge of safety regulations or a desire to not see people encouraged to ignore them? No. Take your FUD and shove it.
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Is the maths or reference to standards I present somehow questionable because of the lack of current equipment that I personally own? Is the personal equipment I own related to my knowledge of safety regulations or a desire to not see people encouraged to ignore them? No. Take your FUD and shove it.
It's fine when you question my statements and ask me to show data to back up my claims. Guessing you were not expecting me to actually follow through. Now that I have and the roles have changed you start whining and telling me to shove it. :-DD :-DD :-DD :-DD
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The meme below comes to mind...
(https://media.tenor.com/RHOtix9Uj30AAAAC/played-yourself-dj-khaled.gif)
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It's fine when you question my statements and ask me to show data to back up my claims. Guessing you were not expecting me to actually follow through. Now that I have and the roles have changed you start whining and telling me to shove it. :-DD :-DD :-DD :-DD
Quite the opposite, I'm happy there are some measured numbers for people to consider but typical figures or calculated examples would have been fine. All I was after was the prospective fault current as your prevailing local standards (of which I know almost nothing about) were likely to be different to the standards we have here.
Measurement categories from 61010 are international and to protect people from (almost) worst case conditions (including faults and transients). Simple rules with almost universal application. Many things could make specific installations/setups less dangerous than that but its then down to (learned) people applying that specifically and not trying to extrapolate out to other situations.
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The meme below comes to mind...
(https://media.tenor.com/RHOtix9Uj30AAAAC/played-yourself-dj-khaled.gif)
joeqsmith measuring a prospective fault current on a socket outlet larger than 1kA? Yep, sounds like it when the meter in question doesnt have the required specifications or ratings to safely withstand that much energy. This thread being about a meter that has a claimed CAT I, and joeqsmith saying it shouldn't be a problem for mains.
Or perhaps these gems from the 61010 standard:
for equipment marked with measurement category I, a warning shall be given not to use the equipment for measurements within measurement categories II, III and IV
Measurement category I is for measurements performed on circuits not directly connected to MAINS
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Fair enough. Which is why I would curious if any UK based electricians here could indicate what kind of prospective fault current would be measured at a typical UK 13 A wall socket? (It would be a range, obviously, but typical/min/max would be interesting.)
Wikipedia says (https://en.wikipedia.org/wiki/Ring_circuit#Description) typical UK ring circuits have 30A fuses and 2.5mm2 cable.
Wikipedia needs editing... what a surprise! Any installation still using fuses would for sure be a Code 2 on an EICR, maybe a Code 1 if the sparky is in a bad mood (yes, there's some wiggle room). Most are going to be MCBs at the least, or RCDs or RCBOs. In any case, for domestic installs they'll be 32A type B, with a 6kA breaking capacity.
The 2.5mm2 T+E has a CPC CSA of 1.5mm2, and in a ring of course there's two paths back to the board (barring fault conditions).
Radials (for socket outlets) are in 4mm2 which also has a 1.5mm2 CPC (used to be 2.5mm2, but hey, cost cutting), and will be protected by a 20A type B MCB/RCD/RCBO.
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Wikipedia needs editing... what a surprise! Any installation still using fuses would for sure be a Code 2 on an EICR, maybe a Code 1 if the sparky is in a bad mood (yes, there's some wiggle room). Most are going to be MCBs at the least, or RCDs or RCBOs. In any case, for domestic installs they'll be 32A type B, with a 6kA breaking capacity.
The 2.5mm2 T+E has a CPC CSA of 1.5mm2, and in a ring of course there's two paths back to the board (barring fault conditions).
Radials (for socket outlets) are in 4mm2 which also has a 1.5mm2 CPC (used to be 2.5mm2, but hey, cost cutting), and will be protected by a 20A type B MCB/RCD/RCBO.
What it actually says is: " They are generally wired with 2.5 mm2 cable and protected by a 30 A fuse, an older 30 A circuit breaker, or a European harmonised 32 A circuit breaker. Sometimes 4 mm2 cable is used if very long cable runs"
But don't let your anti-Wikipedia bias get in your way.
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Wikipedia needs editing... what a surprise! Any installation still using fuses would for sure be a Code 2 on an EICR, maybe a Code 1 if the sparky is in a bad mood (yes, there's some wiggle room). Most are going to be MCBs at the least, or RCDs or RCBOs. In any case, for domestic installs they'll be 32A type B, with a 6kA breaking capacity.
The 2.5mm2 T+E has a CPC CSA of 1.5mm2, and in a ring of course there's two paths back to the board (barring fault conditions).
Radials (for socket outlets) are in 4mm2 which also has a 1.5mm2 CPC (used to be 2.5mm2, but hey, cost cutting), and will be protected by a 20A type B MCB/RCD/RCBO.
What it actually says is: " They are generally wired with 2.5 mm2 cable and protected by a 30 A fuse, an older 30 A circuit breaker, or a European harmonised 32 A circuit breaker. Sometimes 4 mm2 cable is used if very long cable runs"
But don't let your anti-Wikipedia bias get in your way.
I like Wikipedia, and I fund it from time to time. The article header mentions it needs additional verification and citations, and this is a fair assessment. There is some ambiguity and misleading information in it. A circuit breaker old enough to be rated at 30A would be just as bad as a rewirable fuse, and would attract similar comments on an EICR; the tripping times on these old things are so slow as to be positively glacial. I can't recall ever seeing pyro used in a domestic setting. A consumer unit is not the same thing as a distribution board; all consumer units are distribution boards, but not all distribution boards are consumer units.
4mm2 can be used for particularly long runs, but this is not ideal, and would be unlikely to be necessary in a domestic setting, and would be discouraged in any case, due to the negative impact on tripping times. I have seen 6mm2 used on a 20A radial socket circuit; it barely passed muster under testing.
Normally these situations can be avoided by having a better design, ie by having a DB nearer to the load.
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4mm2 can be used for particularly long runs, but this is not ideal, and would be unlikely to be necessary in a domestic setting, and would be discouraged in any case, due to the negative impact on tripping times. I have seen 6mm2 used on a 20A radial socket circuit; it barely passed muster under testing.
How and why does cable size affect tripping times? For example, a 12 m run of 6 mm2 is going to have the same resistance and voltage drop as an 8 m run of 4 mm2 or a 5 m run of 2.5 mm2. Run lengths are going to vary a lot between a large house and a small shed.
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I have seen 6mm2 used on a 20A radial socket circuit; it barely passed muster under testing
how come? the R1 R2 for 6mm is going to be lower than the same length of a bit of 2.5/1.5,meaning your fault current will be higher leading to a faster disconnection time,the only failure i can think of is the fault current being to high for the protective device
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4mm2 can be used for particularly long runs, but this is not ideal, and would be unlikely to be necessary in a domestic setting, and would be discouraged in any case, due to the negative impact on tripping times. I have seen 6mm2 used on a 20A radial socket circuit; it barely passed muster under testing.
How and why does cable size affect tripping times? For example, a 12 m run of 6 mm2 is going to have the same resistance and voltage drop as an 8 m run of 4 mm2 or a 5 m run of 2.5 mm2. Run lengths are going to vary a lot between a large house and a small shed.
You're thinking in terms of DC resistance; this is an AC circuit...
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I have seen 6mm2 used on a 20A radial socket circuit; it barely passed muster under testing
how come? the R1 R2 for 6mm is going to be lower than the same length of a bit of 2.5/1.5,meaning your fault current will be higher leading to a faster disconnection time,the only failure i can think of is the fault current being to high for the protective device
It was a very long run. I can't remember the exact length (this was 10 years ago), but I remember expressing some doubt. Funnily enough I was in the building yesterday, doing some fire alarm and emergency lights testing.
It was for some sockets on columns, in a conference hall. They had to go up and over the ceiling, rather than in the floor; istr there were 4 columns and they used 2 circuits, so 2 columns per circuit. Only 2 double sockets per circuit, but the length would be over 60m I should think.
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You're thinking in terms of DC resistance; this is an AC circuit...
The calculations for 50/60 Hz AC are the same as for DC where resistance, voltage drop and maximum fault currents are concerned.
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You're thinking in terms of DC resistance; this is an AC circuit...
The calculations for 50/60 Hz AC are the same as for DC where resistance, voltage drop and maximum fault currents are concerned.
The PFC is based on the impedance, not resistance, of the CPC.
As for RCD trip times, it's the capacitance of long cables that affects the trip time.