Multimeter CAT II Rating Discontinuation - Page 1
Forum section: electronics / testgear

author: EEVblog
author_rank: Unknown
timestamp: July 23, 2023, 11:08:12 pm
content: I got an email from Brymen:The followings are quoted from safety standard update edition EN61010-2-033:2019 Clause 5.1.5.101. The "CAT II rating" is not allowed anymore for multimeter.In such kind of condition, the ratings of BM235 will need to change from "CAT II 1000V, CAT III 600V & CAT IV 300V" to only "CAT III 600V & CAT IV 300V". Its "CAT II 1000V" rating will need to be deleted in the future.

author: Fungus
author_rank: Super Contributor
timestamp: July 24, 2023, 06:08:44 am
content: I totally called it, LOL!https://www.eevblog.com/forum/testgear/is-cat-ii-a-useful-rating/

author: CosteC
author_rank: Regular Contributor
timestamp: July 24, 2023, 06:27:28 am
content: CAT I was removed some time ago too.On other side, isn't consequence of improved DMM protection, customer ignorance and unfair far east manufacturers?

author: Fungus
author_rank: Super Contributor
timestamp: July 24, 2023, 07:03:37 am
content: Quote from: CosteC on July 24, 2023, 06:27:28 am"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)

author: CosteC
author_rank: Regular Contributor
timestamp: July 24, 2023, 07:52:23 am
content: Quote from: Fungus on July 24, 2023, 07:03:37 amI agree. I am not IEC however. On other side, today it is much easier/cheaper to make well protected input.

author: Someone
author_rank: Super Contributor
timestamp: July 24, 2023, 08:01:26 am
content: Wow, another round of disinformation.Quote from: Fungus on July 24, 2023, 07:03:37 amMeasurement 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/They are safety withstand voltages only, the user should not be injured/shocked if the  transient occurs. No guarantee of functionality or correct operation after the transient.What did change recently is that some standards do not allow a Cat I or Cat II rating to be marked on the instrument, it may still need to pass the requirements for that but it is not shown on the product.

author: Fungus
author_rank: Super Contributor
timestamp: July 24, 2023, 09:02:52 am
content: Quote from: Someone on July 24, 2023, 08:01:26 amCAT II makes sense in some contexts but not in a handheld multimeter.CAT II ratings on handhelds are just a distraction, even an ignorant oaf like me can see that.

author: Gyro
author_rank: Super Contributor
timestamp: July 24, 2023, 09:21:06 am
content: It's going to provide even more incentive for dodgy manufacturers to put CAT III or CAT IV on their meters. Anyone know a good solvent for removing the lettering from mine?

author: Someone
author_rank: Super Contributor
timestamp: July 24, 2023, 09:31:23 am
content: Quote from: Fungus on July 24, 2023, 09:02:52 amSays the person who didn't understand the delineation and was adding further confusion to people trying to understand it (and quotes the link to a standard that isnt the key reference for this when relating to hand held multimeters, further exhibiting your lack of understanding/knowledge).Cat I and II was entirely appropriate for trained personnel, for a consumer device less so.

author: Someone
author_rank: Super Contributor
timestamp: July 24, 2023, 09:32:31 am
content: Quote from: Gyro on July 24, 2023, 09:21:06 am MEK

author: J-R
author_rank: Super Contributor
timestamp: July 24, 2023, 10:48:45 am
content: Hard to find anything about this as it's all behind paywalls, but I found some previews that seem to clarify a few things:"This part of IEC 61010 specifies safety requirements for hand-held multimeters for domesticand professional use, capable of measuring MAINS.Hand-held multimeters are multi-range multifunction measuring instruments intended tomeasure voltage and other electrical quantities such as resistance or current. Their primarypurpose is to measure voltage on a live MAINS. They are suitable to be supported by one handduring NORMAL USE. ""HAND-HELD EQUIPMENT such as oscilloscopes, wattmeters, process control multimeters notRATED for measuring voltage on a live MAINS, clamp multimeters and communications test setsare not within the scope of this document."All this is under the heading "5 Marking and documentation" so it doesn't seem to apply to testing or anything else other than labels.It seems this plan has been in the works for quite some time. I now see most of the DMMs I've purchased in the last maybe 5-10 years don't have CAT II ratings printed on them. Also, I recently purchased the Flir DM64 which we know is basically the BM235 but it is limited to 600V instead of 1000V. (It only has CATIII/IV ratings printed on it.)So this is probably a two-fold plan to reduce confusion/clutter on the face of the equipment to only two ratings, but also boost safety by requiring CATIII/IV for DMMs that you will be measuring mains voltages while holding it in your hand.I'm for sure curious about the clamp multimeter exception, as that seems odd. Maybe it is clarified elsewhere...

author: CosteC
author_rank: Regular Contributor
timestamp: July 24, 2023, 11:50:34 am
content: Quote from: J-R on July 24, 2023, 10:48:45 amThis all is about labels and descriptions on meter and in documentation.Clamp meters do not measure main VOLTAGE hence are not exposed to overvoltages to the same extend.If clamp meter measures mains voltage as additional feature, then falls into handheld DMM I guess.Then CAT I and CAT II are still in use as descriptors for stationary and other non-handheld DMM. Sounds sensible.

author: mendip_discovery
author_rank: Super Contributor
timestamp: July 24, 2023, 01:17:18 pm
content: Gradual phasing out of not-as-safe meter designs. Its not a bad thing. Won't matter to the cheap meters we get from places like China as they will just print whatever ratings they want on there.

author: Fungus
author_rank: Super Contributor
timestamp: July 24, 2023, 01:26:11 pm
content: Quote from: Someone on July 24, 2023, 09:31:23 amPlease tell us all if this outlet is CAT II or cat III:What class multimeter should I use on it?

author: bdunham7
author_rank: Super Contributor
timestamp: July 24, 2023, 01:32:53 pm
content: Quote from: Fungus on July 24, 2023, 01:26:11 pmCan you cite a single example of a non-bullshit DMM that has a CAT II/300V rating? (by "non-bullshit" I mean one where the rating is not just printed on the front as a sad joke)And a related question (one that supports eliminating CAT II...) can you think of a single example of a circuit that would be CAT II/1000V (Category 2 and in excess of 600V) ?

author: Fungus
author_rank: Super Contributor
timestamp: July 24, 2023, 01:43:34 pm
content: Quote from: bdunham7 on July 24, 2023, 01:32:53 pmYou're asking me?

author: bdunham7
author_rank: Super Contributor
timestamp: July 24, 2023, 01:48:32 pm
content: Quote from: Fungus on July 24, 2023, 01:43:34 pmSure, but anyone can chime in.

author: mendip_discovery
author_rank: Super Contributor
timestamp: July 24, 2023, 01:50:35 pm
content: Quote from: Fungus on July 24, 2023, 01:26:11 pmTo me it just looks like a child's first attempt at designing a plug and socket.

author: Dr. Frank
author_rank: Super Contributor
timestamp: July 24, 2023, 02:28:33 pm
content: Quote from: bdunham7 on July 24, 2023, 01:32:53 pmWell, I just inspected my 34465A from KS, 2015, which is rated on its front panel: CAT II (300V)Though, it is able and allowed to measure 1000V DC... I have to check, if this is a contradiction.Anyhow, it is custom in Standardization that a new release of a standard is valid for new products / new development only, but not retroactive.I.e. these DMMs or other instruments should be still 'legal' and shall not be updated somehow.FrankPS: I copy the Regulatory of the 2015 datasheet, which might explain this supposed contradiction of CAT II / 300V vs. 1000V DC.CAT classification to my understanding now relates strictly to measuring Mains voltages.

author: mendip_discovery
author_rank: Super Contributor
timestamp: July 24, 2023, 03:35:32 pm
content: FYI, Fluke's ABCs of multimeter safetyhttps://res.cloudinary.com/iwh/image/upload/q_auto,g_center/assets/3/7/ABC-meter-safety.PDFQuoteThe above statement makes me think that this move to remove more CAT2 stuff is because electricians etc are increasingly at risk of being near a higher power than may initially be expected. With more 3-phase stuff going near car chargers being one thing.

author: CosteC
author_rank: Regular Contributor
timestamp: July 24, 2023, 04:04:12 pm
content: I think it makes more sense in EU than USA and UK.USA is 120 V, so lower, safer voltages.UK is primary single phase systems.EU - in my flat, I have 3 phase (3x230 VAC fixed installation) electric cooker - according to FLUKE it is CAT III, despite IEC61010-1 has other opinion on this topic (FLUKE:) however, per IEC61010-1 installation efore my electricity meter/incomer fuses is CAT III - hence even for "home use" I may need to measure CAT III line for checking if my fuses are fine. To do it I would need CAT III 300 V meter - quite rare thing - most meters is better than this.Per FLUKE lighting in staircase is CAT III - again, IEC 61010-1 would rather categorise it at CAT II - definition of "large building" is vague. Anyway, drawing line between Overvoltage categories is tricky.One more thing, which may affect FLUKE, an USA company: mostly wooden small buildings in USA/UK provide little EM shielding. Buildings in EU are more often reinforced concrete and this providessomelevel of shielding, reducing overvoltages from lighting strikes.Anyway, portable DMM with CAT II only makes indeed little sense, and seems to die out already. For me at least

author: bdunham7
author_rank: Super Contributor
timestamp: July 24, 2023, 04:23:07 pm
content: Quote from: Dr. Frank on July 24, 2023, 02:28:33 pmWell, there you go. Now you can't be sure whether that meter is appropriate to measure the mains in the sockets thatFungusshowed! It also shows the awkwardness of putting CAT-ratings on bench meters, especially the ones with 4W resistance sense jacks rated for much less than the CAT rating on the adjacent jacks. The only bench meter I have that I wouldn't cringe at using on mains doesn't have any CAT rating at all (due to age) and I'd be happy to see the concept of CAT go away on bench instruments.

author: mendip_discovery
author_rank: Super Contributor
timestamp: July 24, 2023, 04:24:23 pm
content: Quote from: CosteC on July 24, 2023, 04:04:12 pmErm UK is mostly stone/brick. Don't lump us in with them weirdos across the pond.The US often has two phases of 120V as they use 240V for some ovens.In the UK most homes are single-phase, and business uses a lot of three-phase. But I know that many housing projects now are starting to go 3 phase due to the electric car market meaning there is going to be a need for more power.

author: bdunham7
author_rank: Super Contributor
timestamp: July 24, 2023, 04:37:25 pm
content: Quote from: CosteC on July 24, 2023, 04:04:12 pmFluke is just providing a brief description and some examples, not a detailed standard. "Commercial lighting" in the US is often 277VAC derived from a 480VAC/3PH service panel, although you can interpret that to include a 120VAC lamp in a hotel room if you like. Just another reason to eliminate CAT II, I guess.QuoteI think the bigger issue in the US would be the prevalence of local low-voltage power distribution outdoors on poles. In theory, if lightning hit the pole behind my house, which is the highest nearby object, it could come directly into my house unimpeded other than my poor circuit breakers.

author: CosteC
author_rank: Regular Contributor
timestamp: July 24, 2023, 04:54:11 pm
content: Quote from: bdunham7 on July 24, 2023, 04:37:25 pmOch. USA electric system is really confusing. 120, 240 277 480... I really prefer European 230/400 VAC, even if you add stubborn UK with its 240 VAC which anyway is the same as "continental" 230 V.Quote from: bdunham7 on July 24, 2023, 04:37:25 pmYou mean home panel distributes technically CAT II but as it is long and on poles it is more CAT III if not CAT IV? Anyway creating grey zone, risky installation.My example in EU is less dangerous and more formal thing. Your example is better. I wonder how some Asia countries or Latin America see it.

author: Fungus
author_rank: Super Contributor
timestamp: July 24, 2023, 05:49:51 pm
content: Quote from: mendip_discovery on July 24, 2023, 01:50:35 pmYes, but you're from the UK.To an American it'll look like something they use at NASA.

author: themadhippy
author_rank: Super Contributor
timestamp: July 24, 2023, 06:19:57 pm
content: QuoteNope, uk's declared voltage is 230V and has been for 20 years

author: Neilm
author_rank: Super Contributor
timestamp: July 24, 2023, 06:46:04 pm
content: If I remember what one of the commitee members told me, I think there is another version of -2-033 due for release this year. I don't remember if it a major change or notIn regards the sockets, it is rated CATII probing in the socket and CATIII if you pull it off the wall and probe the back.

author: Gyro
author_rank: Super Contributor
timestamp: July 24, 2023, 06:59:20 pm
content: Quote from: themadhippy on July 24, 2023, 06:19:57 pmWell, to be more honest, we switched to 230V -6% / +10% as part of European harmonization, ie. we didn't change a damn thing. Coincidentally, our DNO switched our local substation tap to 230V just the other week - about time because we were getting 250V+ before!P.S. It was nearer 30 years.

author: J-R
author_rank: Super Contributor
timestamp: July 24, 2023, 08:31:33 pm
content: US residential terminology is perhaps open for debate, but generally it should be called split phase, not single phase nor two phase. The highest potential from ground is only 120V, so that is why the US outlet design works well enough as-is. You can also get away with touching 120V under most circumstances. Although electrical code at the moment requires arc fault protection, ground fault protection and outlet shutters. The precise combination of those depends on the location. Many homes are grandfathered in but if you perform repairs you must meet the new code.My gripe with the IEC language on the clamp multimeters is that they actually use the word "multimeter" which invites confusion. Hopefully they mean clamp "meters" are exempt but clamp "multimeters" are not if they can measure mains voltages. It's so rare to see a clamp "multimeter" that doesn't measure mains voltages.The power meter statement is even worse as you will be measuring voltage along with current to get the power. So no idea why they would exempt those.Maybe this new revision coming out will clean things up.

author: coppice
author_rank: Super Contributor
timestamp: July 24, 2023, 08:42:16 pm
content: Quote from: Gyro on July 24, 2023, 06:59:20 pmWe still get a minimum of 250V in our house. Is there any stated time scale for the UK actually adjusting everyone's voltage? Is 230V a even a goal any more, now the UK has left the EU?

author: mendip_discovery
author_rank: Super Contributor
timestamp: July 24, 2023, 09:03:57 pm
content: I thought the idea of changing the voltage was to make the sharing of electrical pixies between countries easier.Anyway you can touch 120V and I can confirm it hurts just as much as 230V.

author: coppice
author_rank: Super Contributor
timestamp: July 24, 2023, 09:15:14 pm
content: Quote from: mendip_discovery on July 24, 2023, 09:03:57 pmThat was the goal, but goals change. The main reason we didn't have harmonised voltages in the first place was the urge for countries to be different enough to support local vendors. That wasn't very successful in the long tern, so most product approvals are now to meet global requirements. That could change again, especially if the world seriously backs away from globalisation. If the UK actually stops operating at 240V, will the international product approvals requirements drop from up to 264V to up to 253V?

author: Nusa
author_rank: Super Contributor
timestamp: July 24, 2023, 09:31:34 pm
content: Quote from: coppice on July 24, 2023, 08:42:16 pm230V -6% / +10% never meant changing to 230V. It just meant any voltage between 216.2V and 253V is within spec. The prior UK spec was 240V +/- 6%, or 225.6V to 254.4V, which meant nearly everything was already in compliance from the get-go. Ditto for rest of the EU, at their prior nominal voltages.Electrical infrastructure lasts a long time, so unless you're building significant areas of the grid from scratch, don't expect change to be quick.Of course from the international trade point of view it means that appliances must be designed to operate across the entire mains voltage range in the EU market. Avoiding even the perception of incompatibility was much of the point of the "harmonized" rule.

author: Gyro
author_rank: Super Contributor
timestamp: July 24, 2023, 09:32:58 pm
content: Quote from: coppice on July 24, 2023, 08:42:16 pmThere never was a goal as such to standardize the voltages even if we'd stayed in the EU. The whole European harmonization exercise was just a political / committee exercise. The native 230V countries had a symetrical tolerance, the 240V country (UK) had asymetrical tolerance upwards and the 220V countries, asymetrical downwards. Nobody had any intention of changing anything. Most switching stuff is 90-264V anyway, it still fits in a 400V reservoir cap.The only inconvenience was linear stuff. At 250V, the torroidal transformer in my bench PSU would occasionally hum alarmingly and I had to to knock up an autotransformer to drop the supply to my valve amp (transformer primary wound for 230V - the supplier believed the harmonization hype). I can't see anything to be gained from dropping the design limits to 254V.

author: J-R
author_rank: Super Contributor
timestamp: July 24, 2023, 10:14:46 pm
content: Quote from: mendip_discovery on July 24, 2023, 09:03:57 pmThe fact remains that a higher voltage translates to higher current flow through the body, which is more dangerous.To date I've personally never heard of anyone being electrocuted at their house, but I know a handful that have been electrocuted by trees near overhead power lines. There was actually one just up the road from my house a few months ago. In that specific case, the homeowner wasn't actually cutting the tree down, it fell on the line during a storm. The homeowner walked near the tree to investigate and was electrocuted.

author: Someone
author_rank: Super Contributor
timestamp: July 24, 2023, 11:12:19 pm
content: Quote from: Fungus on July 24, 2023, 01:26:11 pmReally? you want to continue this again and again and again?https://www.eevblog.com/forum/testgear/trashy-meters-redux/msg4832993/#msg4832993https://www.eevblog.com/forum/testgear/is-cat-ii-a-useful-rating/msg4833239/#msg4833239Keep pretending like you are clever and I'll point out that you're just being a troll. The first one of those links is referenced and freely available, but you look the other way and continue to add confusion and misinformation on the matter.The standards are extremely clear on where the different Measurement Categories apply, every single socket outlet is CAT III, things that plug into it are CAT II.

author: bdunham7
author_rank: Super Contributor
timestamp: July 24, 2023, 11:19:46 pm
content: Quote from: Someone on July 24, 2023, 11:12:19 pmYour own linked reference doesn't say that.Category: 2/ Energy level: Low/ Fault current: <5kA/ Applications: Home and office power outlets and lighting circuitsYou might claim that 'outlets' excludes the wiring to them, but I don't see that 'clearly' anywhere and I've seen other reputable sources claim otherwise. Also, at least here in the US, home 'lighting' circuits are indistinguishable from 'outlet' circuits. On fused outlets you can obviously see that the risks change between one side of the socket and the other, but for unfused outlets such as are universal here, there isn't any real difference from the front to the back of an outlet.

author: coppice
author_rank: Super Contributor
timestamp: July 25, 2023, 12:58:10 am
content: Quote from: Nusa on July 24, 2023, 09:31:34 pmIn North London, where I grew up, our mains was generally about 260V at night, and 250V during the day. If you go much beyond that a lot of equipment has MOVs that get quite warm. Its important to know the real world limit for protection design.

author: Fungus
author_rank: Super Contributor
timestamp: July 25, 2023, 04:30:14 am
content: Quote from: Someone on July 24, 2023, 11:12:19 pmWRONG.Fromthe post on the previous page of this thread:That reference has been posted here a million times. You'd think people would have read it by now.Quote from: Someone on July 24, 2023, 11:12:19 pm

author: Fungus
author_rank: Super Contributor
timestamp: July 25, 2023, 05:13:31 am
content: Getting back on topic, the confusion above clearly shows that every outlet should be approachedas if it wereCAT III.(hence all the rules of thumb being posted here)It's also not impossible that a plugged-in device very close to a distribution panel is CAT III, depending on the power cable, etc.That's why I say CAT II multimeters are pointless.

author: Someone
author_rank: Super Contributor
timestamp: July 25, 2023, 05:25:15 am
content: Quote from: bdunham7 on July 24, 2023, 11:19:46 pmWell done referring to a vague "reference" (you could have quoted but didn't). I've quoted AS61010 word for wordhttps://www.eevblog.com/forum/testgear/is-cat-ii-a-useful-rating/msg4833239/#msg4833239Quote from: Someone on July 24, 2023, 08:01:26 am

author: Someone
author_rank: Super Contributor
timestamp: July 25, 2023, 05:27:56 am
content: Quote from: Fungus on July 25, 2023, 04:30:14 amWell done, standards don't say what I can see they say because some other (non-standard document) says otherwise?

author: Kleinstein
author_rank: Super Contributor
timestamp: July 25, 2023, 08:39:22 am
content: Quote from: Fungus on July 25, 2023, 05:13:31 amI would consider an outlett so close (low impedance - not physical distance) to a major distribution panel more a problem with the installation, not such much a problem with the CAT2 meter category.Such outlets should have some kind of warning lable and should be used with care.I have seen the aftermath of a short (flash over in a failing light bulb) on such an installation ( some 2 m from a small breaker box and maybe 3-4 m from the distribution transformer). The 10 kA rated breaker and GFI failed (closed), a 35 A and 100 A fuse blew and the 3x1.5 mm² cable to the outlett turned from gray to brown.I see the higher CAT II ratings a bit pointless for a different reason:Single phase mains is usually 110 V to 240 V nominal. Anything higher voltage (e.g. 480 V 3 phase outletts) tend to be no longer CAT II anyway.

author: Fungus
author_rank: Super Contributor
timestamp: July 25, 2023, 08:47:02 am
content: This is going around in circles as usual.Let's turn it around: Is there anybody here that thinks a CAT II multimeter makes any sense?If not? Thread is finished.

author: Someone
author_rank: Super Contributor
timestamp: July 25, 2023, 10:09:59 am
content: Quote from: Fungus on July 25, 2023, 08:47:02 amYes, plenty of uses for a Cat II multimeter such as production line testing of mains powered plug in equipment. Oh look bench top multimeters are Cat II rated.

author: Fungus
author_rank: Super Contributor
timestamp: July 25, 2023, 11:14:57 am
content: Quote from: Someone on July 25, 2023, 10:09:59 amSo... what meters do they use for that in practice? Brand+model, please.(or is that just an imaginary use?)

author: Someone
author_rank: Super Contributor
timestamp: July 25, 2023, 11:41:10 am
content: Quote from: Fungus on July 25, 2023, 11:14:57 amIts not imaginary, around the facilities I work in daily are multiple brands of bench multimeter that are used for automated testing. Sometimes that is on things that are mains powered but not Cat I isolated/protected, but they are never measuring the building infrastructure.CAT II by definition, CAT II by rating, the right tool for the job.But you seem to have a goldfish memory span as all this has been put in front of you before:https://www.eevblog.com/forum/testgear/trashy-meters-redux/msg4833242/#msg4833242

author: tomud
author_rank: Regular Contributor
timestamp: July 25, 2023, 01:53:35 pm
content: Quote from: Fungus on July 25, 2023, 05:13:31 amSeriously ? So you're saying I should throw the Keysight 34465A (CAT II 300V) and Siglent SDM3065X (CAT I 1000V, CAT II 600V) multimeters in the trash?If someone wants to throw such CAT II multimeter into the trash, please provide the location of the trash.

author: bdunham7
author_rank: Super Contributor
timestamp: July 25, 2023, 03:03:59 pm
content: Quote from: Someone on July 25, 2023, 05:25:15 amMy 'vague reference' wasyour link. I'm not trying to win a debate here--your interpretation makes sense even if it is a bit arbitrary and I would be happy have such a clear and understandable rule. Estimating the distance to my service panel is tedious. I just didn't see any clear evidence presented.If you tell me that these exact words appear verbatim in the standard itself and there is no language that is contradictory or gives further details that would make it less clear, I'll take your word for it.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  voltage installation"The only question I'd have is when you are determining category based on which side of the socket you are on, does that apply to all sockets or just certain smaller ones? Suppose I have a commercial building with an 800A 480V 3PH panel on an inside wall, with a 2MVA transformer (on a 33kV distribution line) right outside the wall. Since this is well into the arc-flash PPE-required domain, this panel is in a separate small electrical room. There is a short length circuit--say 4 feet--of heavy gauge wire going to the next room over where it ends in a pair of L16-30 sockets. This might be a 100A circuit with 2AWG wire. I have a very large SMPS that plugs into this socket and I want to monitor the input voltage across one phase and record it. To do this I want to use my Fluke 8846A, which is rated "CAT II/600V" and I want to record the data using the LAN connector and an ethernet cable attached to my laptop (all aluminum case, of course). Is that all OK? If so, then I'd have to agree with others that CAT II is bullshit since I think this would still be in arc-flash territory, requiring CAT IV/600V and at least some PPE. If it is not OK, I'd have you show me what 'clear' language in the standard says it is not, since I just don't see it in the quote you provided.As far as CAT I/II being deprecated, it certainly appears that they arefor multimetersif the standard now says that the marking shall not be applied. The usefulness of having a CAT II rating is a bit of a different discussion when you start to throw in bench meters. For general-purpose handheld meters I don't see the usefulness of allowing CAT II when CAT III is so easily achieved. I also don't like and don't see the point of CAT II ratings over 300V--you see meters that are CAT II/1000V CATIII/600V CATIV/300V. You might theoretically run into a CAT IV/300V situation--outdoor/underground subpanel feeds, 208V 3PH service panels, etc. I don't see how you would ever run into a CAT II/600V (unless you count my scenario above which would be madness) or CAT II/1000V installation. More than 600V mains and plug-connected with low fault current?

author: bdunham7
author_rank: Super Contributor
timestamp: July 25, 2023, 03:12:08 pm
content: Quote from: Fungus on July 25, 2023, 08:47:02 amFor general-purpose handheld meters, probably not. For bench meters I suppose the CAT II/ (300V only) makes some sense because in certain areas and situations you won't be able to get away with simply not having a CAT rating. Regulations might say that you must have an appropriate CAT rating for any measuring device connecting directly to any mains circuit. Even current clamps have CAT ratings.I'm still waiting for someone to show me a CAT II/1000V scenario.

author: Fungus
author_rank: Super Contributor
timestamp: July 25, 2023, 04:44:49 pm
content: Quote from: tomud on July 25, 2023, 01:53:35 pmYep.Or.... maybe you could follow the discussion and see we're talking about the type of meters that are used by electricians.

author: bdunham7
author_rank: Super Contributor
timestamp: July 25, 2023, 04:54:07 pm
content: Quote from: Fungus on July 25, 2023, 04:44:49 pmI'm sure that's what the first thought was for many, but wouldn't the rule change in the first post apply to the CAT II bench meters as well?OK, I guess I didn't read that carefully. I'd fully endorse removing CAT II from handheld meters intended for mains usage. My reservations about the definition of CAT II remain.

author: Fungus
author_rank: Super Contributor
timestamp: July 25, 2023, 04:58:14 pm
content: Quote from: bdunham7 on July 25, 2023, 04:54:07 pmI think it's very unlikely that they'll ever be connected directly to mains sockets or distribution panels.

author: bdunham7
author_rank: Super Contributor
timestamp: July 25, 2023, 05:14:29 pm
content: Quote from: Fungus on July 25, 2023, 04:58:14 pmWhy not, at least for mains sockets?Someonehas posted that he or his employer uses a CAT II bench meter in this way--perhaps notdirectlyto the socket, but there's not much difference between test leads and a power cord. So if you took away that CAT II rating, some jurisdictions may have regulations that would not allow such an instrument to be connected to mains power.And the rule change appears to do just that if it applies to all multimeters, not just ones sold to electricians.

author: J-R
author_rank: Super Contributor
timestamp: July 25, 2023, 05:29:31 pm
content: Quick reminder, the CAT II labeling removal only applies to handheld DMMs, according to what I posted previously. I have not seen anything yet that states the rating itself is going away or changing otherwise.

author: joeqsmith
author_rank: Super Contributor
timestamp: July 25, 2023, 05:42:54 pm
content: Quote from: J-R on July 25, 2023, 05:29:31 pm

author: bdunham7
author_rank: Super Contributor
timestamp: July 25, 2023, 06:00:40 pm
content: Quote from: J-R on July 25, 2023, 05:29:31 pmDo you know if that is what happened to CAT I or did that go away entirely? I've never understood how CAT I was applied anyway--you see CAT I/1000V on meters that are explicitly not rated for 1000VAC.

author: Fungus
author_rank: Super Contributor
timestamp: July 25, 2023, 06:08:02 pm
content: Quote from: bdunham7 on July 25, 2023, 06:00:40 pmClue: Some meters are incorrectly labelled.

author: J-R
author_rank: Super Contributor
timestamp: July 25, 2023, 06:17:47 pm
content: Since the CAT ratings are safety ratings, it seems logical to me that you could have a device rated for CAT I 1000V but not actually be able to measure it. Although maybe that is not allowed, but without the full document I can't say for sure.

author: bdunham7
author_rank: Super Contributor
timestamp: July 25, 2023, 06:31:58 pm
content: Quote from: Fungus on July 25, 2023, 06:08:02 pmSay it isn't so!

author: alm
author_rank: Super Contributor
timestamp: July 25, 2023, 07:09:37 pm
content: Quote from: bdunham7 on July 25, 2023, 06:31:58 pmWhat is incorrect about that? With surges as defined by CAT II 600V and CAT I 1000 V between any two inputs, the meter won't injure the user or explode. Do you have evidence that those safety claims are false? That would be a major case of fraud I wouldn't expect Fluke to commit.

author: bdunham7
author_rank: Super Contributor
timestamp: July 25, 2023, 08:36:39 pm
content: Quote from: alm on July 25, 2023, 07:09:37 pmI'm not saying it is incorrect, I'm saying it is confusing--at least to me. It's a CAT I/1000V rated meter that can't measure 1000VAC.QuoteI don't think that's a correct or complete statement of the requirements. For example, I don't believe the test procedures specify that the voltage + surge test is done on all ranges. I'm fairly confident Fluke has done their best to apply the standard correctly, but since I don't have it I can't fully understand the details. I'm certainly not claiming the markings are false.I'm not sure at all that the 'any two inputs' requirement applies to bench meters or CAT I/CAT II only devices. And IIRC, Flukes position, or at least their design standard, is not simply that the meter must not explode and injure the user. Here's another model, from the same manfacturer where it seems clearer to me. It also seems evident that the CAT ratings are not meant to apply to the 4W sense jacks.

author: tautech
author_rank: Super Contributor
timestamp: July 25, 2023, 08:51:20 pm
content: Quote from: bdunham7 on July 25, 2023, 08:36:39 pmNormal industry ratings.1kV rated meters generally max out at 750VAC.These do:

author: Fungus
author_rank: Super Contributor
timestamp: July 25, 2023, 10:59:19 pm
content: Quote from: J-R on July 25, 2023, 06:17:47 pmAFAIK the voltage specified in a CAT rating is a voltage that can safely be applied on any input setting.Now we just have figure out what "safely" means - safe for the user or safe for the meter?

author: Fungus
author_rank: Super Contributor
timestamp: July 25, 2023, 11:03:06 pm
content: Quote from: bdunham7 on July 25, 2023, 08:36:39 pmWhat's confusing about it?Not displaying a reading with 1000V input isn't the same as being safe when 1000V is applied.

author: Someone
author_rank: Super Contributor
timestamp: July 25, 2023, 11:05:52 pm
content: Quote from: bdunham7 on July 25, 2023, 03:03:59 pmThat standard does not discriminate between differentplug inequipment, or the outlets they are plugged in to. We have some posters saying they would happily use Cat II out into some parts of their installation, and others saying Cat III is necessary on some of their outlets. Both can be true and appropriate as the standard is only a guidance not some magical 100% true rule of nature that is always correct in every situation ever.The standard just provides for some rules of thumb, that I can point back to as accepted practice if something goes wrong. What's the problem here is a small number of posters trying to argue they can redefine what the standard is to suit their (unknown) motivations, or spread incorrect interpretations of those standards.Yet as I'm typing this there is a user who does not have access to the standards in question is claiming to know what they say, despite being told personally, directly, in public, in this same thread, that what they are saying is incorrect. This forum is turning into a pile of incorrect information from ignorant but noisy posters, drowning out the actually correct and verifiable truth, a general problem with unmoderated internet content.

author: Someone
author_rank: Super Contributor
timestamp: July 25, 2023, 11:10:29 pm
content: Quote from: bdunham7 on July 25, 2023, 06:00:40 pmCAT I still exists within the 61010 standards but is not printed next to the terminals ofhandheldmultimeters (and now CAT II specifications aren't allowed to be printed there either)./thread

author: bdunham7
author_rank: Super Contributor
timestamp: July 25, 2023, 11:38:15 pm
content: Quote from: Someone on July 25, 2023, 11:05:52 pmI don't have any motivations whatsoever other than to try an understand and clarify. 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. I don't have this standard, but other standards that I do know about or are publicly available aren't generally vague and don't require a lot of hand-waving, although you do have to read them carefully and know what all the references and exceptions are. It might explain why they wouldn't want to publish it.It the standards are vague enough to allow some manager somewhere to claim that the CAT II bench meter is good enough for the scenario I laid out, then they aren't helping much. 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 asingle-phasereceptacle/plug, not just any receptacle/plug.

author: alm
author_rank: Super Contributor
timestamp: July 25, 2023, 11:39:44 pm
content: Quote from: bdunham7 on July 25, 2023, 08:36:39 pmOvervoltage ratings are about safety, not the ability to measure. Maybe some internal amplifier would clip, the accuracy would be severely degraded due to V^2/R heating in the divider, or maybe it would even be damaged if exposed repeatedly to 1000 Vrms but not harm the user. Again, IEC 61010 does not care if the equipment keeps working or dies as soon as you turn it on. It's a safety standard, not a quality standard.Quote from: bdunham7 on July 25, 2023, 08:36:39 pmI think they changed that two decades ago to crack down on the "CAT IV 600V on the voltage inputs but a flimsy glass fuse with CAT I 300V for the current input" nonsense. I don't have access to the full standard so I can't give you the exact quote, but the sense terminals should at least be able to handle the max rated voltage (e.g. 1000V DC or AC peak) on all inputs and range/function settings without any danger to the user. From a 2022 draft of IEC 61010-2-030 from CDV that unfortunately only contains changes to the previous version:QuoteSeethis archived page from Gossendescribing how similar language was in the 2002 version. I can't find any authoritative reference saying the transient tests should also be applied to any inputs, though I've seen discussion on the eevblog forums to that effect.

author: bdunham7
author_rank: Super Contributor
timestamp: July 25, 2023, 11:51:59 pm
content: Quote from: alm on July 25, 2023, 11:39:44 pmI don't know what is in the current regulations, but I recall seeing quotes or references to specific language requiring the meter to be able to detect and display the presence of hazardous voltages even after the transient test. There was some discussion about degraded accuracy and such, but this is clearly a safety issue as well--if a transient can suddenly cause the meter to display 000.00V when the circuit is still live, that's not good.I think it is likely that manfacturers could interpret all this in different ways, and one takeaway point is that just like with accuracy specifications, it is not very helpful to directly compare instruments from different manufacturers solely by their specified ratings.From a Fluke advertorial:In the impulse testing phase, Fluke multimeters are subjected to repeated jolts of high voltage to prove they can withstand voltage spikes from lightning or other causeswithout damage to the productor harm to their users. The higher the voltage or measurement category where the product will be used, the higher the test voltage applied—up to 12,000 volts for products designed for CAT IV/1000V environmentshttps://www.fluke.com/en/learn/blog/safety/fluke-lab-tortures-test-tools-so-technicians-feel-no-pain

author: bdunham7
author_rank: Super Contributor
timestamp: July 25, 2023, 11:55:44 pm
content: Quote from: tautech on July 25, 2023, 08:51:20 pmI get it, I've seen many and I'm used to it. I think it is unhelpful and especially confusing when you have a CAT I/1000V rating and the separate AC measurement limitation is not on the face of the meter. If you have to read the manual to know something as simple as the maximum voltage rating, that's not optimal.

author: tautech
author_rank: Super Contributor
timestamp: July 26, 2023, 12:35:31 am
content: Quote from: bdunham7 on July 25, 2023, 11:55:44 pmYet operating the meter beyond ratings is normally met with OL on the display.One normally expects those playing with such voltages have some idea what they are doing.How much need a manufacturer hold the hand of their users ?

author: Martin72
author_rank: Super Contributor
timestamp: July 26, 2023, 12:46:36 am
content: Actually, not at all, it is enough to indicate to what extent you are allowed to use the device.I don't know where it is regulated differently, but here only trained electricians are allowed to measure voltages that go beyond what is just not life-threatening.

author: Someone
author_rank: Super Contributor
timestamp: July 26, 2023, 01:28:47 am
content: Quote from: bdunham7 on July 25, 2023, 11:38:15 pmYou're on point here, the standards do not have a string of complex clauses for the definitions of Measurement Categories, its laid out plainly as I provided direct word for word quotes of.Yes, the delineations are not perfect but there is no perfect delineation as the world is complex. This is layers of abstraction as the Measurement Categories define the limits of the safety tests, so all that compliance to a specific Measurement Category defines is that the product won't cause a hazard within those defined synthetic test conditions..... which have been chosen by the committees based on historical data and experience to generally cover the real world situations.Why is it so hard for people to understand?The standard is a specific limit that is considered representative of the real world.There will be real world examples worse than that (but they will be very few/unusual)There will be real world examples that are benign and never even approach the limit (common, routine, normal, typical, most situations)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.

author: Fungus
author_rank: Super Contributor
timestamp: July 26, 2023, 07:42:49 am
content: Quote from: bdunham7 on July 25, 2023, 11:38:15 pmTo 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.Quote from: bdunham7 on July 25, 2023, 11:38:15 pmYep.

author: joeqsmith
author_rank: Super Contributor
timestamp: July 26, 2023, 05:56:50 pm
content: Quote from: Fungus on July 26, 2023, 07:42:49 amNot 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.

author: Someone
author_rank: Super Contributor
timestamp: July 26, 2023, 10:19:28 pm
content: Quote from: joeqsmith on July 26, 2023, 05:56:50 pmYes, 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.

author: bdunham7
author_rank: Super Contributor
timestamp: July 27, 2023, 03:15:53 am
content: Quote from: Someone on July 26, 2023, 01:28:47 amOK, but I think the much smaller point I'm trying to make is that the delineation could bemuch 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.QuoteBecause it doesn't make intuitive sense and results in absurd results in certain very plausible situations like the case I proposed.QuoteMy 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.

author: bdunham7
author_rank: Super Contributor
timestamp: July 27, 2023, 03:31:20 am
content: Quote from: tautech on July 26, 2023, 12:35:31 amI 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.

author: Someone
author_rank: Super Contributor
timestamp: July 27, 2023, 06:18:52 am
content: Quote from: bdunham7 on July 27, 2023, 03:15:53 amThe standard 61010, is only about product safety and communicating its safety limits,notabout 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.

author: bdunham7
author_rank: Super Contributor
timestamp: July 27, 2023, 07:44:05 pm
content: Quote from: Someone on July 27, 2023, 06:18:52 amThat 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.

author: Someone
author_rank: Super Contributor
timestamp: July 27, 2023, 10:58:49 pm
content: Quote from: bdunham7 on July 27, 2023, 07:44:05 pmPretty 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).

author: bdunham7
author_rank: Super Contributor
timestamp: July 27, 2023, 11:59:17 pm
content: Quote from: Someone on July 27, 2023, 10:58:49 pmI'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.QuoteThat 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.QuoteYou 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.

author: Someone
author_rank: Super Contributor
timestamp: July 28, 2023, 12:51:29 am
content: Quote from: bdunham7 on July 27, 2023, 11:59:17 pmAgain 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:Quote from: Someone on April 26, 2023, 11:03:53 amThose are word for word quotes [editor rewording in bracket] from AS61010-1:2003which I have a licensed copy of, and its currently in force and up to date:Quote from: Someone on July 24, 2023, 08:01:26 amSo 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:Quote from: Someone on July 27, 2023, 10:58:49 pmFluke 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 knowcategoriesof 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.

author: bdunham7
author_rank: Super Contributor
timestamp: July 28, 2023, 01:08:30 am
content: Quote from: Someone on July 28, 2023, 12:51:29 amOK, 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.

author: Someone
author_rank: Super Contributor
timestamp: July 28, 2023, 02:41:23 am
content: Quote from: bdunham7 on July 28, 2023, 01:08:30 amThis 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.

author: Fungus
author_rank: Super Contributor
timestamp: July 28, 2023, 01:34:28 pm
content: Quote from: Someone on July 28, 2023, 12:51:29 amAnd 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 sayingandit 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.

author: Fungus
author_rank: Super Contributor
timestamp: July 28, 2023, 01:38:55 pm
content: Quote from: Someone on July 28, 2023, 02:41:23 amI 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.

author: Someone
author_rank: Super Contributor
timestamp: July 28, 2023, 10:27:30 pm
content: Quote from: Fungus on July 28, 2023, 01:38:55 pmBecause 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.

author: Someone
author_rank: Super Contributor
timestamp: July 28, 2023, 10:35:29 pm
content: Quote from: Fungus on July 28, 2023, 01:34:28 pmBecause 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.

author: joeqsmith
author_rank: Super Contributor
timestamp: July 29, 2023, 02:57:05 am
content: 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.

author: Someone
author_rank: Super Contributor
timestamp: July 29, 2023, 03:48:27 am
content: Quote from: joeqsmith on July 29, 2023, 02:57:05 amI 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

author: Fungus
author_rank: Super Contributor
timestamp: July 29, 2023, 05:00:48 am
content: Quote from: Someone on July 28, 2023, 10:27:30 pmHuh? You yourself said:"As mentioned in the other thread(s), its very very simple: something that plugs into a socket outlet isimmediatelyCAT II"Quote from: Someone on July 28, 2023, 10:27:30 pmThat analogy would work perfectly if all sockets had a built-in 10 Ohm resistor as a "fence".But they don't.

author: Someone
author_rank: Super Contributor
timestamp: July 29, 2023, 05:22:03 am
content: Quote from: Fungus on July 29, 2023, 05:00:48 amand no one says that they do, except your imaginary strawman argument.

author: HKJ
author_rank: Super Contributor
timestamp: July 29, 2023, 05:54:52 pm
content: 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.

author: EEVblog
author_rank: Unknown
timestamp: July 12, 2024, 12:56:04 am
content: Had totally forgotten about this change to CAT II. Just found out that my new EEVblog branded pocket multimeter will not have 500V CAT II marked on the front because they will not certify it to the new standard if you print it on there.The product had previous had it marked, but because I changed the model number they have to recertify it and hence it can't have CAT II printed any more