Do we need to have CAT III 1000V and CAT IV 600V? - Page 1
Forum section: electronics / testgear

author: BeBuLamar
author_rank: Super Contributor
timestamp: February 12, 2022, 06:21:04 pm
content: In buying DMM for a number of people in our company I think the Fluke 114 or 116 have the features that they need as compared to the 87V and 287 we often buy. These people never need any functions above the 114 ( I am thinking of the 116 because they do need to measure flame rod current once in a great while). I don't want them to use the DMM for current at all. However, one thing bothers me that the 114 and 116 don't have the CATIII and CAT IV rating the same as the 87V or 287. Should we need it? We do have to work with 480V services.

author: ControlsLost
author_rank: Contributor
timestamp: February 12, 2022, 07:15:28 pm
content: Everything works until it doesn't...CatIII vs CATIV from my understanding purely derives from the instruments ability to withstand transients in the line while connected (transient being a voltage spike, catIII somewhere around 6kv and catIV being around 8kv.... I think...)so if you want to measure anything industrial that is inside the building, coming from a main electrical distribution panel, then you'd be at CATIII minimum. that means at 600v CATIII, the meter was tested to withstand transients found in lines of that origin. and the ratings have to do with the location in a circuit because of the impedance..... the farther away from the incoming utility, the more wire and impedance and protection ciruits there are, so the less you need to worry about high voltage transients as the amount of energy will be much less by then.If you want to use something in an industrial cabinet. then minimum is CATIII 600v. (unless your cabinet is high voltage. {High Voltage by OSHA standards is 600v and up}Please correct me if i'm wrong.

author: ControlsLost
author_rank: Contributor
timestamp: February 12, 2022, 07:22:38 pm
content: As far as the meters are concerned. what kinds of things do they intend to use them for?I typically suggest for others that have asked, that they go with the 117. the only difference between the 116 and 117, is the 116 has temp measurements and the 117 has voltalert instead of temp.realistically, the 87v is a better meter in my mind. and if you want to have a low impedance check like the LO-z feature, then buy the low impedance adapter for fluke meters with it.I don't believe the 116 or 117 have low pass filters for VFD work, so this all depends on what your people need.In the end, if you are wanting 116 or 114 instead of an 87, that sounds like a cost thing?

author: BeBuLamar
author_rank: Super Contributor
timestamp: February 12, 2022, 08:27:56 pm
content: First I want to eliminate current measurement capability and that is why I don't want the 117. I don't want the people I buy the meter for use the DMM to measure current at all especially doing it by mistake. Accuracy is not important. Lo Z is a feature I want them to have. There is no need to measure VFD output. The meter would be use in industrial control cabinet where generally the main voltages are 480 3 phase up to 400A. I basically want to restrict them to only certain functions but I am concerned about safety.

author: Fungus
author_rank: Super Contributor
timestamp: February 12, 2022, 08:36:39 pm
content: Have you looked at the 113? If safety is a concern then there's very little to mess up there, it may be one of Flukes safest meters if you take "procedural safety" into account. It's also permanently "Lo-Z" so they can't forget to use that function.Keep a special meter around for the rod current.

author: BeBuLamar
author_rank: Super Contributor
timestamp: February 12, 2022, 08:43:25 pm
content: I have the 113. I have problems measuring voltages with it. It can be confusing at times if the voltage you measure is too low it switches between continuity mode and voltage mode if the voltage you are measuring is about 1.xxx V or so. Also I don't want to use the lo Z on 480. When I use it like that there is a spark when I touch the probe to the voltage source.

author: Fungus
author_rank: Super Contributor
timestamp: February 12, 2022, 08:48:26 pm
content: Quote from: BeBuLamar on February 12, 2022, 08:43:25 pmYes, you couldn't use it in a hobby context. It's for mains AC and "electrician stuff" only.Quote from: BeBuLamar on February 12, 2022, 08:43:25 pmVisual voltage indication.

author: ControlsLost
author_rank: Contributor
timestamp: February 12, 2022, 08:51:52 pm
content: I would never want to use an auto-selecting function, I've seen some that show AC when it's just a terrible DC source, etc.But in all honesty, If they are supposed to be going into a live controls cabinet and you're worried about all these things so much that you want to restrict their usage down to almost nothing then they could use more training. Specifically for their own safety and usage.But why not just give them what most other industrial places give them, like a t6-1000 or fluke 124? Amp clamps give the extra amp check function and limit meter usage to the basics (although very low resistance checking capabilities).

author: BeBuLamar
author_rank: Super Contributor
timestamp: February 12, 2022, 08:58:07 pm
content: We have been issuing them with Fluke 87V and 287 along with 376FC or 381 clamp meters. But I feel the extra functions don't help them. They never use them. I don't worry about cost. The tester isn't good enough because they do need to check diode and capacitor.

author: threephase
author_rank: Regular Contributor
timestamp: February 12, 2022, 11:03:13 pm
content: CAT IV instrumentation is for use at the distribution source, CAT III is used beyond that at control panels and motor control centres etc.For electricians we would issue a voltage indicator and clamp meter. If values are required we would go for a voltage indicator with a digital display on it such as the T5 from Fluke, if not we would just use the LED indicator type.

author: bdunham7
author_rank: Super Contributor
timestamp: February 13, 2022, 12:59:53 am
content: Quote from: BeBuLamar on February 12, 2022, 08:58:07 pmI have a 116 with an i400 current clamp for these very reasons. It simply cannot be blown up by misconnection in any mains scenario from 480/277 on down and it still has the diode, continuity, uA for flame rods and leakage testing, capacitance, temp, etc. It also has the Lo-Z mode built in. One lesser-known feature is the Lo-Z capacitance that will measure a motor start/run capacitor while it is energized (one side only, not with the motor running!) although it takes some tricky button presses to get into it.I don't know about the CAT rating thing. Internally the protection looks as good as anything else, IIRC. The meter is a 6000-count device and 600.0V is the top range, so perhaps it is a combination of cost-saving and market segmentation. CAT-III/600V should be adequate for 480/277 and less anywhere downstream of the service entrance/main breaker/meter. Maybe splurge on some TL-175 TwistGuard leads and AC-175 insulated alligator clips (these are really nice!) if you want to keep everyone safe.

author: Someone
author_rank: Super Contributor
timestamp: February 13, 2022, 03:17:27 am
content: Quote from: BeBuLamar on February 12, 2022, 06:21:04 pmBut are those CATIII or CATIV situations? If they are and something goes wrong, the person (you?) who made the choice that the extra protection wasn't required will be hung out to dry. Since you are asking the question to an open forum its clear youshouldntbe making or providing input on those decisions.

author: bdunham7
author_rank: Super Contributor
timestamp: February 13, 2022, 03:50:53 am
content: Quote from: Someone on February 13, 2022, 03:17:27 amhttps://res.cloudinary.com/iwh/image/upload/q_auto,g_center/assets/3/7/ABC-meter-safety.PDFOne thing I think that gets forgotten is that all outdoor mains cables--overhead or underground--are technically considered CAT IV. So according to that, my F116 would not be acceptable for working on my swimming pool wiring, which is 240VAC/ split-phase (120V to ground) on a 20A breaker and has a short underground feed in conduit. Despite the transient testing, etc for CAT IV/300V being the same AFAIK as CATIII/600V, Fluke has not put that rating on these meters for some reason. Likewise, the CATIII/1000V rated F27 would also not technically meet the requirement.I personally wouldn't let that worry me--a 480VAC 3PH panel is a lot more dangerous than my swimming pool--but that's how the rules state it, at least as explained by the Fluke publication here.Another thing that I would keep in mind is, as I alluded to earlier, test leads. I think good quality CAT IV rated test leads (not everything in the CAT ratings is about transient testing) will do more to keep you safe than worrying about the meter getting hit by lightning.

author: Someone
author_rank: Super Contributor
timestamp: February 13, 2022, 04:23:33 am
content: Quote from: bdunham7 on February 13, 2022, 03:50:53 amWow, even the 116 has a fairly solid rating but as you say insufficient for "normal" residential stuff by some jurisdictions standards/interpretations. Over here a an outdoor household feed to a shed/garage is still Cat III.Quote from: bdunham7 on February 13, 2022, 03:50:53 amToo often you see electrical trades with worn out test leads (fixed with electrical tape etc!).

author: Fungus
author_rank: Super Contributor
timestamp: February 13, 2022, 04:32:50 am
content: Quote from: bdunham7 on February 13, 2022, 03:50:53 amYep.Quote from: bdunham7 on February 13, 2022, 03:50:53 amI've never really understood the relationship between measured voltage rating and transient.It doesn't matter if you'remeasuring300V or 600V, a lightning strike is a lightning strike. The transient will be the same.Impedance is the same for CAT III and CAT IV, so...

author: bdunham7
author_rank: Super Contributor
timestamp: February 13, 2022, 05:09:36 am
content: Quote from: Fungus on February 13, 2022, 04:32:50 amThere's probably more to it and whatever models they are using are probably not perfect. And then you have the issue of condensing and simplifying the rules to make them easier to understand and apply. So simply making all outdoor conductors CAT IV works even though it may seem a bit ridiculous at times.

author: Fungus
author_rank: Super Contributor
timestamp: February 13, 2022, 05:12:20 am
content: Quote from: BeBuLamar on February 12, 2022, 08:27:56 pmPeak voltage on that is obviously over 600V so you need a 1000V rated meter.A CAT III 1000V rated meter should be fine there but as you've noticed, Fluke doesn't make one without current measurement (apart from the 113, which you don't like). I can only assume it's for marketing reasons because surely the demand is there for an industrial meter without current measurement. They also don't have any CAT IV 1000V meters at all - they wouldn't want to upset any of their cash cow meters. Shenanigans like this is one of the reasons I'm not a Fluke Fanboy.What's the answer?Maybe one of their "electrical tester" range:https://www.fluke.com/en-us/product/electrical-testing/basic-testers/fluke-t-plus-pro

author: Fungus
author_rank: Super Contributor
timestamp: February 13, 2022, 05:24:19 am
content: Quote from: bdunham7 on February 13, 2022, 05:09:36 amI have no problem classifying them as CAT III vs. CAT IV.I'm wondering how they can specify different transient levels in "outdoor" meters, lightning doesn't care.(and neither do big coils of wire when they produce CAT III inductive spikes)

author: bdunham7
author_rank: Super Contributor
timestamp: February 13, 2022, 05:27:54 am
content: Quote from: Fungus on February 13, 2022, 05:12:20 amCAT ratings are based on RMS AC. CAT III/600 should be OK inside a typical indoor 480V installation.

author: Muttley Snickers
author_rank: Unknown
timestamp: February 13, 2022, 05:52:43 am
content: Fluke 174?There is a full review of the Fluke 174 on Youtube if anyone is interested. I couldn't watch the video so won't post a link here.

author: Fungus
author_rank: Super Contributor
timestamp: February 13, 2022, 06:13:33 am
content: Quote from: bdunham7 on February 13, 2022, 05:27:54 amThe OP specified a three phase system so difference between phases is a lot higher.Fluke's web page says their meters are rated for "Maximum voltage between any terminal and earth ground".eg.480V AC is 678V peak between live wire and ground.

author: bdunham7
author_rank: Super Contributor
timestamp: February 13, 2022, 06:26:35 am
content: Quote from: Fungus on February 13, 2022, 06:13:33 amYou may have seen me refer to it as 480/277. That's 480VACRMSphase to phase with 277VACRMSphase to neutral near ground potential, a fairly standard industrial power type. Some larger systems may have 575 volts in a three-phase configuration, usually for large motors. Still probably ok at CAT III/600.And maximum simply means maximum RMS voltage, not instantaneous peak. That may not always be clearly stated, but that's what they mean.

author: Nusa
author_rank: Super Contributor
timestamp: February 13, 2022, 07:21:22 am
content: Quote from: BeBuLamar on February 12, 2022, 06:21:04 pmDo your people EVER work on outside lines? That includes service panels on outside walls, exterior equipment, buried cables, or drops to service buildings. Those are all CAT IV situations, regardless of voltage. If you're in the USA as your tag suggests, buy CAT IV meters to cover you and your companies legal butt. Doesn't matter what logic says is good enough, it's about what the NFPA codes say is required should someone have an accident while using a meter.

author: Fungus
author_rank: Super Contributor
timestamp: February 13, 2022, 07:27:06 am
content: Quote from: bdunham7 on February 13, 2022, 06:26:35 amThat's 757V difference if somebody messes up and pokes the wrong wires....or if they're trying to figure out which wire is which....or if the wires are installed incorrectly - you're often there to diagnose faults.

author: mendip_discovery
author_rank: Super Contributor
timestamp: February 13, 2022, 12:05:44 pm
content: BeBuLamar I like that you are trying to think of alternate solutions to just buying bulky expensive meters for a given task. You are attempting to expand your knowledge on defining the risks of a meter not being marked as rated for Cat III / IV. IIRC the 121GW doesn't fit some specifications just because you can open it to access the memory card. Some of the comments here seem to apply the "Duh, you gotta use it as it says so" mentality. But I personally find that following H&S requirements without understanding them is just as dangerous, I go into lots of factories and get some odd responses from the H&S chap when I ask why I require a hard hat etc. I don't have an issue with wearing it, I just like to know what is likely to hit me so I can avoid the issue in the first place.I would strongly suggest you do some risk assessments/requirements around the use of the meters. Even if you choose to go down the 87 route still do it because it shows why you choose that option and protects you in the future when purchasing type buys some incorrectly rated equipment. I would also put in place a regular inspection of the test gear to ensure the test leads are in good condition and not putting people at risk.Here in the UK we have government places (Health and Saftey Executive) that give us some guidance you might want to have a read of it just to add to your knowledge,Electrical test equipment for use on low voltage electrical systemsSafety in electrical testing at workElectricity at work - Safe working practicesElectrical safety and you - A brief guideQuoteI suspect you will be stuck needing to use the correctly rated gear to protect your ass. Unless you can reduce the risks with protected test areas, RCD protectors etc etc. But if it is fieldwork then you don't have much choice.So if you have to use the 87, to prevent users from using the current option get some of those blanking plugs to prevent easy access into the Current terminals, even going as far as removing the fuse. Again document what you did and why. There is a saying I hear some of the Cat1 agencies use "When facing the person with a curly wigg, if it isn't written down, it didn't happen" which refers to if you get put in front of a judge, at an inquest of why something bad happened if you failed to make sufficient written down notes then relying on "I told", "someone said" etc won't help you. There is a whole thread dedicated to meters that appear not to meet the requirements they say they do. Does pose the argument are there meters that exceed the requirements but for some reason are not marked up for it.

author: bdunham7
author_rank: Super Contributor
timestamp: February 13, 2022, 03:19:23 pm
content: Quote from: Fungus on February 13, 2022, 07:27:06 amNo, the phase-to-phase is the maximum voltage between any two wires, even in weird delta systems with one leg grounded.

author: bdunham7
author_rank: Super Contributor
timestamp: February 13, 2022, 03:41:31 pm
content: Quote from: Nusa on February 13, 2022, 07:21:22 amI'm not sure about service panels on outside walls, but indeed the rest of it appears to be CAT IV. However, I think the legal liability issues here are often overstated. The way to avoid legal issue is to not have the accident in the first place, which the OP is trying to do by eliminating the current jacks, among other things. The likelihood of the meter vaporizing due to a transient in a CAT IV environment are quite miniscule compared to all of the other things that are likely to go wrong and cause an electrical catastrophe.If the meter is intended to be used indoors as the OP stated, and the worry is that someone might occasionally take it outdoors when they aren't supposed to, I'd say that itself isn't worth worrying about--at least the meter part. Employee training and compliance would worry me more.

author: Fungus
author_rank: Super Contributor
timestamp: February 13, 2022, 04:24:36 pm
content: Yep. Procedure and training is just as important as the meter.Do they wear gloves and hearing/face protection when poking at that big power distribution panel?There's a reason 100% of the images on the Fluke web site show that instead of this:I still think OP should look at an electrical tester instead of a "multimeter".eg.https://www.fluke.com/en-us/product/electrical-testing/basic-testers/fluke-t-plus-pro#Those things have a higher CAT ratingandare designed to avoid procedural errors.

author: bdunham7
author_rank: Super Contributor
timestamp: February 13, 2022, 06:09:02 pm
content: Quote from: Fungus on February 13, 2022, 04:24:36 pmIn combination with something like the F116 that would be a good idea. Especially if they do need CAT IV occasionally, then the technician will have a 'proper' tool available. Perhaps one of the fork testers would be good--the T5-1000 only costs slightly more then the i400 current clamp.https://www.fluke.com/en-us/product/electrical-testing/basic-testers/fluke-t5-1000Note that you would want different probe tips than the ones that are pictured.https://www.fluke.com/en-us/product/accessories/kits/fluke-t5-kit