Multimeter CAT II Rating Discontinuation

[Fungus]

But I'm a bit doubtful that they would be that flawed or that Fluke would deliberately (or even negligently) publish false information that clearly contradicts what you are claiming is the standard.  My best guess, based only on speculation and language from Fluke's reference, is that there is additional language specifying a single-phase receptacle/plug, not just any receptacle/plug.

To me that "10m from CAT III" seems like a very specific thing, something that Fluke wouldn't invent if it wasn't in the standard. That document has been around for many years and it makes perfect sense that the danger from transients diminishes gradually with distance, not in sudden steps. I'll need a lot of convincing that Fluke is wrong and a random forum poster is right.

If the 'standard' here is just 'guidance' that provides rules of thumb and expects you to fill in the rest with common sense, than IMO that's not much of a standard.

Yep.

[joeqsmith]

... makes perfect sense that the danger from transients diminishes gradually with distance, not in sudden steps. I'll need a lot of convincing that Fluke is wrong and a random forum poster is right.   ...

Not just incoming transients.  Fault current goes up.  Think about the idiots that try and measure the AC current by placing the meter in current mode across the mains.   I took some measurements a while back in my home for someone showing how the distance effects it.    Also measured some larger outlets at work for fun.   

Still a big difference between the kid plugging sissors into the home wall socket and the service tech arching a 480 bus.   

[Someone]

... makes perfect sense that the danger from transients diminishes gradually with distance, not in sudden steps. I'll need a lot of convincing that Fluke is wrong and a random forum poster is right.   ...

Not just incoming transients.  Fault current goes up.  Think about the idiots that try and measure the AC current by placing the meter in current mode across the mains.   I took some measurements a while back in my home for someone showing how the distance effects it.    Also measured some larger outlets at work for fun.   

Still a big difference between the kid plugging sissors into the home wall socket and the service tech arching a 480 bus.

Yes, the real world is highly variable. Fluke presents some suggestions of what they think are appropriate conditions given the specific ratings of their meters, but that is not supported by or in the standard, just some practical advice from a manufacturer. Would I rely on that advice to cover my liabilities? No.

[bdunham7]

Yes, the delineations are not perfect but there is no perfect delineation as the world is complex.

OK, but I think the much smaller point I'm trying to make is that the delineation could be much better (not perfect) by simply adding the language "single phase receptacle".  Fluke has somehow read in or added this specific language but perhaps they've just added their own common sense take to the standard...I don't know.  And the IEC appears to be moving in the right direction, IMO. 

Why is it so hard for people to understand?

Because it doesn't make intuitive sense and results in absurd results in certain very plausible situations like the case I proposed.

Otherwise you end up with an impossible to meet standard that covers a soaking wet gorilla probing a socket outlet outside in the rain, which is connected back to the poles with some obscure 120mm2 cable, during lighting strike on the nearest pole.... and the meter needs to continue operating perfectly afterwards despite being on current mode and connected across the phases.

My contrived example was based on things that I've either seen and handled myself or that I'm actually sure exist and are reasonably common.  I understand the need for some simplicity and that they don't want to require a complete fault current analysis signed off by a PE before anyone can ever connect a meter to anything.  That doesn't mean there isn't room for improvement and if what you insist about the standard is correct, there's some pretty low hanging fruit there IMO.

[bdunham7]

How much need a manufacturer hold the hand of their users ? 

I think they should do the easy, common sense things that make it possible for a someone with experience with similar equipment, but not identical, to use its basic functions without reading the manual.  Now if we're talking HF AC, then I don't expect them to have a pull-out chart to guide me through that.   

[Someone]

Otherwise you end up with an impossible to meet standard that covers a soaking wet gorilla probing a socket outlet outside in the rain, which is connected back to the poles with some obscure 120mm2 cable, during lighting strike on the nearest pole.... and the meter needs to continue operating perfectly afterwards despite being on current mode and connected across the phases.

My contrived example was based on things that I've either seen and handled myself or that I'm actually sure exist and are reasonably common.  I understand the need for some simplicity and that they don't want to require a complete fault current analysis signed off by a PE before anyone can ever connect a meter to anything.  That doesn't mean there isn't room for improvement and if what you insist about the standard is correct, there's some pretty low hanging fruit there IMO.

The standard 61010, is only about product safety and communicating its safety limits, not about how/where to use the device. That standard divides the product specifications into Measurement Categories for the purposes of confirming to their different safety tests, nothing more, and describes the typical situations they expect those (broad and simple to define) categories apply to.

In real world that maps to use the majority of the time. But a learned/educated user knows what the different CAT ratings mean in voltages and current, so they can be confident where a CAT II could be safely used on some part of the permanent wiring. But only because they have measured or calculated things like the prospective fault current and know there is a lightning arrestor etc. In the absence of that extra information the simple explanations are a good start but not infallible, local workplace safety laws then come in and say how you should actually choose an appropriate rating (which in Australia lines up directly the 61010 standards delineations).

I think the 61010 standard are a good balance of simple delineations and realistic limits that aren't too hard to achieve. That may not work in other countries with their specific electrical codes.

[bdunham7]

The standard 61010, is only about product safety and communicating its safety limits, not about how/where to use the device. That standard divides the product specifications into Measurement Categories for the purposes of confirming to their different safety tests, nothing more, and describes the typical situations they expect those (broad and simple to define) categories apply to.

That seems reasonable and understandable to me.  But if the language you posted is simply a description of typical examples then it is just dicta (explanation) and not actually part of the standard's requirements per se.  That doesn't seem to mandate a universal bright line rule that the border between CAT II and CAT III is alway exactly at the wall socket body.  If certain jurisdictions adopt a policy that does match that (hopefully adding the 'single phase' part) then that becomes your rule.  That doesn't make it universally clear for everyone and I don't think that policy has been adopted here in the US.

[Someone]

The standard 61010, is only about product safety and communicating its safety limits, not about how/where to use the device. That standard divides the product specifications into Measurement Categories for the purposes of confirming to their different safety tests, nothing more, and describes the typical situations they expect those (broad and simple to define) categories apply to.

That seems reasonable and understandable to me.  But if the language you posted is simply a description of typical examples then it is just dicta (explanation) and not actually part of the standard's requirements per se.  That doesn't seem to mandate a universal bright line rule that the border between CAT II and CAT III is alway exactly at the wall socket body.  If certain jurisdictions adopt a policy that does match that (hopefully adding the 'single phase' part) then that becomes your rule.  That doesn't make it universally clear for everyone and I don't think that policy has been adopted here in the US.

Pretty much, the 61010 standard makes a Measurement Category delineation as an example and not as some golden rule that must be implemented by installations, other equipment, and working practices, the standard is just defining safety compliance tests of measurement equipment. The categories being models that are used to motivate the tests. But if you see a 61010 Measurement Category specified on a meter/product then you know what voltages/current is claims to survive, and it is a quick way to ask as one example "will this meter be safe under a 5kA fault?" which is roughly the worst case we would see on a socket outlet (3 phase 50A outlet at a 1% droop).

The 61010 standard clearly says their definition of Cat II vs Cat III is either side of the socket outlet. Other standards/practices (as in Australia) have adopted that. Noisy posters continuously question that in obnoxious fake concern and without basis.

Measurement Categories are defined by 61010 (and some other standards) no-one gets to redefine them locally/personally and claim the 61010 standard is wrong, that's inventing some other new categories of some other different standard. If you want to talk CAT xx then refer to the standard that's defining it and there is zero room for variation/misunderstanding/confusion (that some posters seem intent on pushing/persisting).

[bdunham7]

the standard is just defining safety compliance tests of measurement equipment. The categories being models that are used to motivate the tests. But if you see a 61010 Measurement Category specified on a meter/product then you know what voltages/current is claims to survive....

I'm good there--there's a table of voltage and surge test levels for each catetgory.  The CAT rating of a meter is based on or verified by which tests and inspections it can pass.

The 61010 standard clearly says their definition of Cat II vs Cat III is either side of the socket outlet.

That directly contradicts what you just said above.  A CAT II (xxxV) meter is one that passes the stated surge test (and other requirements of course) and CAT III meter is likewise one that passes its respective tests.  The standard mentions that an example of a CAT III environment is the wiring behind a wall socket.  But that in no way 'defines' what a CAT III meter is and you have just said that the CAT ratings are related to the capabilities of the meters and not definitive statements about where the meters are used. 

Noisy posters continuously question that in obnoxious fake concern and without basis.

You can disagree all you want if you think the two lines you've quoted without context (not that I'm expecting you to provide it) are the final authority, but questioning peoples motives and claiming the counterarguments are 'without basis' is a bit much.  The information Fluke publishes on the matter directly contradicts what you are claiming and I'm not willing to write them off as badly misinformed idiots just yet.  That and their interpretation or explanation makes a lot more sense. 

[Someone]

The 61010 standard clearly says their definition of Cat II vs Cat III is either side of the socket outlet.

That directly contradicts what you just said above.  A CAT II (xxxV) meter is one that passes the stated surge test (and other requirements of course) and CAT III meter is likewise one that passes its respective tests.  The standard mentions that an example of a CAT III environment is the wiring behind a wall socket.  But that in no way 'defines' what a CAT III meter is and you have just said that the CAT ratings are related to the capabilities of the meters and not definitive statements about where the meters are used. 

Noisy posters continuously question that in obnoxious fake concern and without basis.

You can disagree all you want if you think the two lines you've quoted without context (not that I'm expecting you to provide it) are the final authority, but questioning peoples motives and claiming the counterarguments are 'without basis' is a bit much.  The information Fluke publishes on the matter directly contradicts what you are claiming and I'm not willing to write them off as badly misinformed idiots just yet.  That and their interpretation or explanation makes a lot more sense.

Again with your vague/non specific references to "something". Please quote if you think something specific is incorrect.

To make this blindingly obvious I'll keep quoting in context:

Fluke isn't following the standard from which those categories are defined (61010) and would be misleading in typical installs in Australia and the UK (and probably other countries that I am less familiar with).

61010 measurement categories are really simple:
"CAT III is for measurements performed in the building installation"
"CAT II is for measurements performed on circuits directly connected to the [mains] voltage installation"

As mentioned in the other thread(s), its very very simple: something that plugs into a socket outlet is immediately CAT II, unless you are on the other side of safety isolation/insulation and then its up to you to know what the range of voltages/currents could be (perhaps use a more modern standard to help) and check that the multimeter/measurement tool has suitable withstand and/or breaking capacity.

Those are word for word quotes [editor rewording in bracket] from AS61010-1:2003
which I have a licensed copy of, and its currently in force and up to date:

Wow, another round of disinformation.

CAT I was removed some time ago too.

"CAT I" is useful information - it lets you know the meter won't die if you apply the rated voltage with the meter set to Ohms (for example).

(assuming a CAT rating means "meter won't die at this voltage" - something else they ought to clarify in the standard

Measurement Categories I and II are not discontinued or removed, AS61010 still lists them as current:
https://infostore.saiglobal.com/en-us/standards/as-61010-1-2003-121163_saig_as_as_254253/

So where in that I am contradicting myself? A direct quote of what the standard says, is... what it says. All these "arguments" that it means or says something else are factually incorrect. AS61010 definitions of Measurement Category:

The 61010 standard clearly says their definition of Cat II vs Cat III is either side of the socket outlet.

Fluke may well provide different guidance on where they see those measurement categories applying, but that does not change the standard or override it. They have not rewritten or produced some new standard, or said what they write is communicating the 61010 standard (Fluke reference the earlier IEC 1010). Its some marketing material that uses Measurement Categories as you know categories of measurement products and how they think that maps to the (US centric) "real world".

Fluke nowhere claim to be providing a copy or representation of the 61010 standard, yet now you're claiming that too. Where is the basis for that claim? Fluke only talk about IEC 1010, where as Dave in the OP talks about 61010.

Or as a simple example of why the Fluke examples are misleading (in other countries only?) is that Australia requires a maximum droop in the voltage at socket outlets under maximum load. The length of the cabling is pretty much irrelevant to the fault current as we are required to maintain the same (maximum worst case) source impedance at any length. This argument has already been presented, yet here we are again with mutltiple people saying FLUKE IS OUR GOD, TRUST FLUKE there can be no other truths.... while completely misunderstanding and misrepresenting what Fluke are communicating.

[bdunham7]

Those are word for word quotes [editor rewording in bracket] from AS61010-1:2003

OK, then I'll just go back to what I said earlier which was essentially that if you are correct as to the applicability of the quoted language, then the standard itself is flawed could use some very simple reworking to avoid the situation I described earlier.  A non-binding 'explanation' is one thing, but a bright-line rule should be better IMO.  It appears they've started in that direction, perhaps they'll take up my suggestions next.

And since you pointed out that Fluke is referencing a different standard, I now have noticed that you are referencing an Australian standard from 2003?  Is that updated and harmonized to the current or near-current EN61010-(1 or 2)? I don't know how that works, but Dave's reference appears to be showing updates to EN61010-12:2019 that will appear in EN61010-12:2023.

[Someone]

And since you pointed out that Fluke is referencing a different standard, I now have noticed that you are referencing an Australian standard from 2003?  Is that updated and harmonized to the current or near-current EN61010-(1 or 2)? I don't know how that works, but Dave's reference appears to be showing updates to EN61010-12:2019 that will appear in EN61010-12:2023.

This is the point, you're all shouting from the hills about you know best and my contributions are questionable. Yet there is no basis for that as the evidence you rely on it actually something other than you claimed it to be. Keep coming back with more shade throwing and "questions" that you can't be bothered to check or answer and that's not disproving what I'm saying, that's being dick and just creating massed insinuations to try and flood out any possible replies. When you're the one who's been continually failing to substantiate your points or even produce a coherent argument, this is descending into stupidity.

IEC 61010-2-033 is scoped to hand-held multimeters, but that sits under the larger 61010 umbrella.

AS61010 is typically harmonised against European IEC standards, there may be slight differences between the various international versions but I don't have them to hand to verify that. Pulled up a BS EN61010-1:2010 of unknown providence. The (sub) standards refer to each other, BS EN61010 in a normative Annex:
"The concept of OVERVOLTAGE CATEGORIES is elaborated in IEC 60364 and in IEC 60664-1."
and has no definitions of Measurement Categories, where as IEC 61010 has Measurement Category used extensively.

You care about EN61010? Buy yourself a copy. Engage in the standards process. Stop posting crap here. Go out and learn about the standards that you claim to care so much about.

[Fungus]

To make this blindingly obvious I'll keep quoting in context:

Fluke isn't following the standard from which those categories are defined (61010) and would be misleading in typical installs in Australia and the UK (and probably other countries that I am less familiar with).

61010 measurement categories are really simple:
"CAT III is for measurements performed in the building installation"
"CAT II is for measurements performed on circuits directly connected to the [mains] voltage installation"

As mentioned in the other thread(s), its very very simple: something that plugs into a socket outlet is immediately CAT II, unless you are on the other side of safety isolation/insulation and then its up to you to know what the range of voltages/currents could be (perhaps use a more modern standard to help) and check that the multimeter/measurement tool has suitable withstand and/or breaking capacity.

And to make it blindingly obvious why we don't bow down to that, 61010 also mentions source impedance:


I don't agree that source impedance is exactly 2 ohms at the back of all sockets and I don't agree that it changes by exactly 10 ohms across the socket.

The "source impedance" definition of CAT II and III agrees more with what Fluke is saying and it makes more sense from a theoretical viewpoint, ie. a gradual increase in source impedance as you move away from the distribution panel, not some arbitrary (and large!) steps.

[Fungus]

You care about EN61010? Buy yourself a copy. Engage in the standards process. Stop posting crap here. Go out and learn about the standards that you claim to care so much about.

I simply don't believe there's a huge step in danger from the front to the back of a socket.

If that's what the standard says then the standard needs revising.

[Someone]

You care about EN61010? Buy yourself a copy. Engage in the standards process. Stop posting crap here. Go out and learn about the standards that you claim to care so much about.

I simply don't believe there's a huge step in danger from the front to the back of a socket.

If that's what the standard says then the standard needs revising.

Because you keep insisting that is what the standard says... when it does not. Obvious troll is now obvious.

The 61010 standard provides a series of categories that model the real world. You can do with that information what you like. But so far all you seem to do with that is say you dont like their model. WHICH IS FINE. The standard is not wrong, it does not say either side of a socket outlet is magically radically different electrical characteristics. What is conveyed is that the faults/voltages/currents expected to be seen in the real world can be speaparted at that point for most practical purposes.

Do you go to the zoo and step over the fence to demonstrate there are (almost) never tigers behind the first layer? Your choice. Are there never tigers in the public walkways? less often but non-zero. The delineation is made somewhere, additional safety is made somewhere (61010 definitions of CAT II vs CAT III is the delineation between single insulation and double insulation in many regions).

As you quoted, if this is such a big issue for you go and buy the standard and engage in their process. Dont shoot the messenger.

[Someone]

And to make it blindingly obvious why we don't bow down to that, 61010 also mentions source impedance:


I don't agree that source impedance is exactly 2 ohms at the back of all sockets and I don't agree that it changes by exactly 10 ohms across the socket.

Because nowhere does the standard say that. You keep forcibly injecting your repeatedly failed argument over and over and over, when it's purely your imagination. The source impedances of the standard are for the test setup, which with their over voltage (which scales across the Measurement Categories) ends up being representative of something close to worst case in the real world. Nowhere does it say that is what installations are/do/shall be only that the standard believes this is representative of worst cases within those categories.

[joeqsmith]

Both the general as well as the surge standards talk about the source impedance.   The UL standard mentioned states 2,12 & 30 for the impulse generator's source impedance depending on the category. 

[Someone]

Both the general as well as the surge standards talk about the source impedance.   The UL standard mentioned states 2,12 & 30 for the impulse generator's source impedance depending on the category.

I would be interested in hearing more about the US (and German from the other thread) local practices/standards for delineating/labelling/recognising different hazard groups/categories. Here in Australia the Measurement Categories have been adopted directly:
https://www.worksafe.qld.gov.au/news-and-events/newsletters/esafe-newsletters/esafe-editions/esafe-electrical/2022-newsletters/june-2022/multimeter-incidents

[Fungus]

The standard is not wrong, it does not say either side of a socket outlet is magically radically different electrical characteristics.

Huh? You yourself said: "As mentioned in the other thread(s), its very very simple: something that plugs into a socket outlet is immediately CAT II"

Do you go to the zoo and step over the fence to demonstrate there are (almost) never tigers behind the first layer? Your choice. Are there never tigers in the public walkways? less often but non-zero.

That analogy would work perfectly if all sockets had a built-in 10 Ohm resistor as a "fence".

But they don't.

[Someone]

The standard is not wrong, it does not say either side of a socket outlet is magically radically different electrical characteristics.

Huh? You yourself said: "As mentioned in the other thread(s), its very very simple: something that plugs into a socket outlet is immediately CAT II"

Do you go to the zoo and step over the fence to demonstrate there are (almost) never tigers behind the first layer? Your choice. Are there never tigers in the public walkways? less often but non-zero.

That analogy would work perfectly if all sockets had a built-in 10 Ohm resistor as a "fence".

But they don't.

and no one says that they do, except your imaginary strawman argument.

[HKJ]

Real life conditions do not necessary have to match exactly the conditions that the standard specify, the test conditions will usually be some simplified version of the real life conditions.

Also note that the impedance for mains voltage do not have anything to do with the impedance of transients, they come from two different sources with different impedance.