Fluke 179 Multimeter Fuse - Page 1
Forum section: electronics / repair

author: bostonman
author_rank: Super Contributor
timestamp: September 26, 2022, 03:23:23 am
content: Think I accidentally blew the 440mA fuse in my Fluke 179.These replacement ones seem costly ($7.49 on Amazon). Does anyone know where to find similar lower cost versions?

author: bdunham7
author_rank: Super Contributor
timestamp: September 26, 2022, 03:40:16 am
content: They're expensive and apparently commonly faked. I believe the ones from Witonics are genuine, but I couldn't prove it. I'd stick with a reliable supplier and live with the expense. You can buy a 5-pack of these from TEquipment for under $30.

author: bostonman
author_rank: Super Contributor
timestamp: September 26, 2022, 03:44:56 am
content: I hadn't considered fake ones, but this is good to keep in mind.You're correct on not chancing cheaper priced ones that could be fake because one can save a few bucks, but end up blowing an expensive meter.Fluke could have used standard versions, but bet they did this so you have to buy their fuses.

author: bdunham7
author_rank: Super Contributor
timestamp: September 26, 2022, 04:04:33 am
content: Quote from: bostonman on September 26, 2022, 03:44:56 amNo, they did that to meet safety requirements and prevent you from turning yourself into ash when you accidentally short out an industrial service panel with your meter because you left the leads in the current sockets. Look at the interrupt ratings on those fuses--the small one can interrupt a fault current of 10,000 amps.Edit: Case in point...https://www.ecmweb.com/safety/arc-flash/article/20898038/the-case-of-the-deadly-arc-flash

author: Black Phoenix
author_rank: Super Contributor
timestamp: September 26, 2022, 11:10:31 am
content: Exactly. There is a reason why such fuses are used, not because it is what a brand wants to milk money from the consumer.Case and point other brands of equipment that are certified for such work and have the proper international safety certifications use same kind of fuses or of similar construction.Normally I bash Fluke because of their price practices, lack of innovation and "milking" 20+ year old designs with minor updates (87 series for example) but in terms of safety they are second to none, together with other brands as Brymen, Hioki, Amprobe, Gossen Metrawatt and Kyoritsu.

author: bostonman
author_rank: Super Contributor
timestamp: September 26, 2022, 12:36:54 pm
content: I indirectly owe Fluke an apology then for accusing them of trying to have an edge on replacement fuses.I haven't opened the meter yet to measure the fuse as I'm avoiding to open it, close it, open it again, and then close it. Most likely I accidentally touched the two leads when measuring current. The connector I needed to connect to was a tiny Molex or whatever, so i used staples as pins to clip onto, but, in the process of moving around, the staples turned and must have touched; thus blowing the fuse.Sadly, I didn't even need to measure current, but was just curious about how much the device was drawing.Thanks for the feedback - I'll plan to spend the extra few dollars instead of searching for cheaper ones that could end up being a knock off.

author: unknownparticle
author_rank: Frequent Contributor
timestamp: September 26, 2022, 02:30:37 pm
content: Basically, don't buy off ebay or even Amazon, particularly if the seller admits to being located in China. There are more fake sources than genuine.There is a youtube vid, probably more than one actually, but the one I saw dismantled a fake and a genuine fuse to reveal the difference. The fake was utter cr4p, the genuine very impressive.

author: Gyro
author_rank: Super Contributor
timestamp: September 26, 2022, 07:41:18 pm
content: It's a shame Fluke abandonded the dual fuse approach that they used on the old Fluke 25 / 27. They had a small 20mm 630mA 250V ceramic fuse, with a big 3A 10kA fuse in series to clear any high energy fault that the little one couldn't. In most cases, the little 20mm fuse would clear the fault, leaving the expensive one intact.The 10A range was still a single 10kA fuse - 15A in those days but the shunt was bigger and higher thermal mass.

author: bdunham7
author_rank: Super Contributor
timestamp: September 26, 2022, 07:52:56 pm
content: Quote from: Gyro on September 26, 2022, 07:41:18 pmThat was a handy setup, also found on the 8840A/8842A series, but you might notice that no meter with that setup has a CAT rating (AFAIK). Even the later CAT-III/1000V 27 has abandoned the dual fuse setup, so perhaps there's a valid reason. I simply use an external fused 1R shunt setup I made when I'm doing something like measuring a small current in a device powered by a large source--like a car battery.

author: Gyro
author_rank: Super Contributor
timestamp: September 26, 2022, 08:05:39 pm
content: Yes, hard to say, they were pre-Cat rating and they had abandoned the approach generally by the time the later 27 had come along. I found an original ad for the early 25/27 which said they have 6kV surge rating at 600V which I suppose would have made them CAT III 600V (the main fuses were 600V too). It's hard to think that the 10kA wouldn't clear the fault if the 20mm one arced over (without exploding) [Edit: just as you would expect it to blow before the mA shunt clamp diodes], they presumably tested it thoroughly as they were Mil spec and MSHA mine certified. I really don't know though.Yes, I usually use external shunts for miniumum burden too, I have quite a collection.

author: bdunham7
author_rank: Super Contributor
timestamp: September 26, 2022, 08:28:55 pm
content: Quote from: Gyro on September 26, 2022, 08:05:39 pmI've always thought it was a good design and I've never heard of an issue, but I wonder what would happen if you connected it to a 1000VDC @ 3A source--that would arc over the little fuse indefinitely but the 3A wouldn't blow the big one. That's a corner case that is resolved by simplifying the product, easy to sell to management.

author: Gyro
author_rank: Super Contributor
timestamp: September 26, 2022, 08:36:06 pm
content: Yes, I suppose it was an easy sell, especially when they were using single main board space rather than the seperate vertical fuse board.P.S. I recently acquired a decent Fluke 25 with both main fuses blown. Some *** had blown the 15A fuse and then put the 3A fuse in its place and blown that too. The 20mm fuse was of course intact.

author: Black Phoenix
author_rank: Super Contributor
timestamp: September 27, 2022, 02:24:54 am
content: Quote from: Gyro on September 26, 2022, 07:41:18 pmWhat's the problem of the fuse doing their function, ie, blowing up? Why the old design was better than the newer design? How regularly you blow up fuses?In 15 years I've been using DMMs I blow up 1 fuse at total. That's what 30 euros in 15 years. That's one less coffee I drink per year.The fuse function is to protect the operator in case of a fault. It's a consumable. Same as the DMM. If you blow up the fuse or the DMM you can buy a new one. I didn't see extra lives to be sold anywhere as in games...

author: james_s
author_rank: Super Contributor
timestamp: September 27, 2022, 02:32:35 am
content: Quote from: Black Phoenix on September 27, 2022, 02:24:54 amThe only thing wrong is the price. I can see the value in having both a cheap fuse and an expensive fuse in series, with the cheap fuse likely to blow in the sort of casual mistakes that happen sometimes while the expensive fuse is still there to save you from a catastrophic mistake. It's true that one normally doesn't blow fuses very often but it does happen once in a while, and it's annoying when it happens and you haven't got a spare on hand.

author: robert.rozee
author_rank: Frequent Contributor
timestamp: September 27, 2022, 03:06:12 am
content: Quote from: Black Phoenix on September 27, 2022, 02:24:54 amthe answers lie in the following case:https://www.ecmweb.com/safety/arc-flash/article/20898038/the-case-of-the-deadly-arc-flashthe fuse needs to not only 'blow', but also interrupt the current flow prior to any mechanical rupturing. once 'blown', you doNOTwant the fuse and body to be replaced with a glowing ball of highly-conductive plasma. the large fuses you see in fluke (and other) meters are filled with sand around the fuse element, and are enclosed in an explosion-proof fibrous body that can contain the contents long enough for any plasma to cool down. they are a quite high-tech device, far more than just a bit of fuse wire.the above link is why ionlyuse fluke meters on mains (230v here) and higher voltages. it only takes one accident to be removed from the gene pool!cheers,rob :-)

author: Black Phoenix
author_rank: Super Contributor
timestamp: September 27, 2022, 03:25:44 am
content: Quote from: robert.rozee on September 27, 2022, 03:06:12 amRob, thanks for your reply but you didn't understood my question.As I stated here:Quote from: Black Phoenix on September 26, 2022, 11:10:31 amI said the same as you, but with different words.My question is aimed at Gyro who states that the old design of double fuse (one glass and one big one in series) was preferable to him because of the fact that it would not blow the big one most of the times, so saving money and the hassle of replacing it.That's why I asked what I asked. Other than cost related (that still as I said I don't see as a minus since I blown one fuse in 15 years) I don't understand why such design in his idea is preferable to the current one.

author: james_s
author_rank: Super Contributor
timestamp: September 27, 2022, 03:45:08 am
content: Quote from: Black Phoenix on September 27, 2022, 03:25:44 amIt's exactly cost, because not everyone is as careful as you. I don't blow them very often but I have blown them, especially back before I had a clamp probe. It depends on what you're doing, with some use cases it's a lot easier to blow the fuse than others.

author: Black Phoenix
author_rank: Super Contributor
timestamp: September 27, 2022, 04:39:06 am
content: Quote from: james_s on September 27, 2022, 03:45:08 amNot careful, more like I rarely use the amp function in my DMMs and when I use it is mostly low amp applications. When I need to use on expected to be higher amps I use a clamp probe.But yes, I understand your reasoning and agree with it.

author: Gyro
author_rank: Super Contributor
timestamp: September 27, 2022, 09:22:45 am
content: Quote from: Black Phoenix on September 27, 2022, 03:25:44 amFirstly, please note that nowhere did I mention "glass" fuses. The use of a low breaking capacity physically fragile glass fuse would be patently ridiculous in a serious meter safety setting.My point was simply that Fluke used the double fuse approach to avoid blowing the large and expensive 10kA breaking capacity mA fuse, designed to clear faults in CAT III / IV situations, due to a silly mistake (eg. forgetting a large capacitor inrush, or forgetting the jacks) in a Cat I environment, you might almost say wasteful. It's not something I make a habit of (I haven't blown one for years, but I'm retired now) but people tend to be a little less cautious on the bench than situations where they may receive an arc flash in the face! Having blown such a fuse, you areduty boundto replace it with a suitable replacement to maintain the integrity of the meter. Unfortunately this leads to delay (unless in a lab with spares stock), frustration , and of course cost - hence the flourishing market in fake fuses . Even in a large development lab, I remember the gentle ridicule and teasing that people suffered when going for a replacement meter fuse (one step down from having to tell the calibration dept that you had wrapped the needle on your AVO or blown the 50R terminator on your scope!). At least one member on here has admitted to bridging the fuse with a thin strand of wire, and you too frequently hear of examples of test equipment where this has happened - my 25 was probably one step away from that fate when I got it, with both 10kA fuses already blown.At some point, somebody at Fluke said 'let's not do that any more' and we will never know why. As I mentioned previously they did it on their most rugged DMM, with all sort of certifications, which was marketed for many years. They must have done extensive testing of the safety of the dual fuse approach. Apart from the corner case that bdunham7 mentioned (which I suspect would actually be sucessfully quenched by the 20mm fuse), there are many internal parts that rely on the 10kA fuse to safely clear a fault in CAT II+ environmentsincludingPCB traces, clamping diodes, switch contacts etc. This would all have been tested.I would love to see Joe Smith put a Fluke 25 / 27 through it's paces, I think the closest he has come is the Fluke 77, but that used spark gaps rather than 5 MOVs. Even then, he does not have the capability to test high current fault clearing. It would probably be one for Photoinduction!Comprehensive testing would require a large pile of expensive fuses anyway.As I mentioned, I also rarely use meter current ranges (none of my bench meters even have them), but I felt duty bound to replace the fuses with genuine items anyway (again, to maintain the integrity of the meter). I have a bunch of shunts, ranging from 1k (1mA) up to 150A. These of course are only suitable for CAT 1 lab bench environment (maybe occasionally CAT II in a UK fused plug environment). Current clamp probes are a godsend for AC in higher CAT environments, much less satisfactory for measuring low DC leakage currents in the same situation.

author: Gyro
author_rank: Super Contributor
timestamp: September 27, 2022, 10:18:14 am
content: Quote from: robert.rozee on September 27, 2022, 03:06:12 amThat accident happened because the meter was a fake. Wrong PCB clearances, little glass fuse, untested against specification. It's markings and specifications were false. It should never have been where it was. Sad and sickening like all arc flash incidents but not relevant to the Fluke discussion.In the fluke case, the 10kA fuse would have taken on the fault clearance as soon as the current rose significantly above 3A. 20mm Ceramic fuses (also sand filled) typically have an interrupt rating of 1.5kA @250V on their own.

author: Black Phoenix
author_rank: Super Contributor
timestamp: September 27, 2022, 11:23:29 am
content: Quote from: Gyro on September 27, 2022, 09:22:45 amMy mistake sorry. And as I also said to James, I understand the situation at hand and agreed.In such use you demonstrated, yes it would be logical the double fuse in series logic. Sorry for calling the wrong fuse type.Now it would be good to know why Fluke changed that approach. I remember coming around a topic where the OP was a Fluke employee and was in the design/engineering team responsible for DMMs. It would be good to have his input in case he could shed some light about this.

author: Gyro
author_rank: Super Contributor
timestamp: September 27, 2022, 11:40:42 am
content: No problem.It's one of those problems where your instinct says the approach should work but you don't know why they abandoned it, and there's no sensible way of testing it. It certainly wouldn't work with a 35A interrupt glass fuse, but the ceramic has a considerable interrupt rating of its own, way above what would be needed to bring the 10kA interrupt fuse into the game.That would indeed be a thread worth finding (I think I remember the thread you're talking about now). Irrc, he was responsible for the very early Fluke designs (the ones with the row of buttons down the side - 8060), pre 25 and 8840, but may have some insight.EDIT: Found it...https://www.eevblog.com/forum/testgear/old-fluke-multimeters/It looks as if drtaylor was still active here in March.EDIT 1: Another twist. Looking at the 8060 manual, it (and, from the above thread, the 8020) also included two series fuses, a user replaceable 20mm / 1" 2A 250V and a service replaceable 600V 3A 10kA one. The plot thickens.

author: bdunham7
author_rank: Super Contributor
timestamp: September 27, 2022, 01:58:35 pm
content: Quote from: Gyro on September 27, 2022, 10:18:14 amActually the situation there was a bit different. The meter wasn't 'fake', and it didn't have any ratings at all IIRC. It was simply a primitive model and thus didn't comply with any modern standards, even though it was manufactured more recently when those standards were, well, standard--but not mandated. The case against the manufacturer was simply that they had designated it as an "industrial" model. More importantly to this discussion, the electrician was measuringvoltage,not current, and there's no allegation that he connected the meter improperly. That particular meter used a fuse in the voltage circuit--to protect the meter, not the user--as do some other analog meters from previous eras. I believe even some Simpson VOMs are like this, although I don't know what brand was involved here. I would never use something like my Simpson 270 on a high-energy 3-phase panel! In the case of a modern Fluke, there would not have been any blown fuses and the meter would presumably withstand whatever transient was on the mains, probably without damage--although we don't actually know how powerful that surge was.

author: robert.rozee
author_rank: Frequent Contributor
timestamp: September 27, 2022, 02:30:35 pm
content: Quote from: Gyro on September 27, 2022, 10:18:14 amthe meter (in the linked article) was not a "fake", it was just badly designed. while it did not have a IEC 600V CAT III rating (as would be required for the job it was performing), neither did it make any claims that it did have such a rating. its main legal sins were claiming to be an "industrial multimeter" (a meaningless term) and having a scale on the analog face with markings going up to 1000v. these were sufficient to fool the victims into feeling a false sense of safety.given a multimeter has a small 'sacrificial' fuse in series with a 10kA fuse (ie, early fluke), there is risk that a fault condition could knock out the sacrificial fuse in such a way that a plasma ball can form within the meter housing. at that point, the 10kA fuse is unlikely to even still be in the path of current flow, and the destruction of the meter will be well underway; as the linked article says, "the victims' fates were sealed".if, on the other hand, youJUSThave the 10kA fuse in line, it will blow, in theory containing any plasma within the fuse housing until it has been safely extinguished. this may end in the fuse rupturing, and the insides of the meter being destroyed. but the meter and fuse will have fulfilled their job - containing everything within the meter's housing.note that the multimeters are (or at least should be) designed to be destroyed under certain fault conditions, but still contain damage to within the meter's housing and leave the user unharmed. the multimeter is itself a 'sacrificial' device.cheers,rob :-)

author: Gyro
author_rank: Super Contributor
timestamp: September 27, 2022, 05:40:43 pm
content: Quote from: robert.rozee on September 27, 2022, 02:30:35 pmI stand corrected. Not having details of the meter or it's front panel markings it's hard to judge how clear the telltail signs would have been, it clearly wasn't suitably CAT rated but there's no telling how obvious this would have been. There's a lesson in there about borrowed equipment and anotherhugeone from the photo of the probe with remains of an alligator clip! Regardless of the rating of the meter, anything other than proper protective shrouds, exposing just a couple of mm of tip, on the test probes would have immediately de-rated them to CAT II at any voltage - that was easily enough to have been the direct cause such an accident on its own. The other slight inconsistency is that, from the description, the electrician was already measuring voltages when the arc flash occured so the (totally inadequate) fuse probably wasn't actually in circuit at the time but that's irrelevant in the scheme of things. 1000V on the scale shouldn't have been enough to fool the individuals on its own (there aren't many meters without a 1kV range) the term 'industrial' is tricky It's the sort of labelling that rings warning bells. As with most of these cases, there are a bunch of contributing factors - I always find such pictures distressing.QuoteTherein lies the question. I suppose it would be easy to substitute a piece of copper rod for the 20mm fuse but it does seem counterintuitive. It hinges on the amount of testing that Fluke carried out... and on the rise time of the fault current. The 10kA is a maximum permissible quench current, the large fuse ought to be able to clear the fault long before that. There is a case for it in CAT II conditions though.Yes certainly, the construction of the case is an integral part of the protection, its internal blast shield moldings, the depth of the case flanges and the ultimate impact strength of the case material are all key. Everything is ultimately sacrificial apart from the user.

author: Black Phoenix
author_rank: Super Contributor
timestamp: September 28, 2022, 01:17:49 am
content: Quote from: Gyro on September 27, 2022, 05:40:43 pmYes but let's not forget that even the equipment being a "sacrificial tool", PPEs were not present too.Just because a Fluke can withstand a transient of thousand of volts without harm to the user, that doesn't mean I would go all in, blindly, without any PPE.

author: bostonman
author_rank: Super Contributor
timestamp: October 17, 2022, 03:29:12 am
content: The 179 manual lists the part number as 943121, but the Fluke website shows 203411. I'm uncertain if a difference exist.Unfortunately not only does Fluke not have any in stock, but they are $21.50 each. TE has them for $7 each and are in stock.Think I'm safe with these or does a possibility exist that they can be fake:https://www.tequipment.net/FlukeFuses943121.html?v=0Edit: TE lists two part numbers in their fuse selection guide. 203411 (which matches the Fluke website), but has the five pack under a different part number 203414, however, a Fluke 179 isn't listed in both part numbers implying they are different fuses (I assume it's a part number for a five pack, but the same fuse).

author: Black Phoenix
author_rank: Super Contributor
timestamp: October 17, 2022, 10:13:50 am
content: Quote from: bostonman on October 17, 2022, 03:29:12 amThe fuses sold by TE are the correct fuses, you can go with them. Te list the 179 in the description of the item.

author: bostonman
author_rank: Super Contributor
timestamp: October 17, 2022, 12:09:29 pm
content: Do you think the five pack and the single ones are the same even though they are different part numbers and don't list the 179 in the description for both?

author: Black Phoenix
author_rank: Super Contributor
timestamp: October 17, 2022, 01:52:03 pm
content: But of course. The difference between item no are basically database entries.They can't be the same, so a unit have a part no. A box with 5 units is another part no.

author: bostonman
author_rank: Super Contributor
timestamp: October 17, 2022, 01:55:24 pm
content: That's what I assumed, but the list of meter model numbers isn't in the quantity five part number description implying they are different fuses.Obviously I understood they are the same fuse, but they are confusing the viewer by not listing the 179 in both part numbers.

author: Gyro
author_rank: Super Contributor
timestamp: November 13, 2022, 08:57:32 pm
content: On a whim, I revisited this the other day - this being, the early Fluke approach of fitting series 600mA 20mm x 5mm ceramic fuses (250V, sand filled, 1.5kA breaking) in series with a standard Fluke large 3A 600V 10kA meter fuse on the mA current ranges. In my case on a Fluke 25.The cost advantage of only having to replace a cheap sacrificial 20mm fuse most of the time is clear but the discussion was centering around whether this early approach was safe, whether the 20mm fuse could explode or arc over under extreme fault currents, and whether it was actually safer to replace the 20mm fuse with a piece of copper rod or whatever (probably yes).I've now fitted a Littlefuse 230V 10kA GDT from stock, in heatshrink for extra protection, across the rear of the 20mA fuseholder. My thinking is along the lines of the GDT capturing the current if the 20mm fuse blows at mains voltage high fault current, and taking out the main 10kA fuse.This is a very academic question, as I am not in the habit of using DMM current ranges, blowing fuses, or using DMMs on high energy circuits. I have Cat III+ stuff for that anyway. I'm certainly not going to waste the cost of the 10kA breaking fuse with some sort of high energy capacitor discharge test rig. I just wondered what others think.The only potential fault scenario I can think of at the moment is the 20mm fuse failing to break the fault current and its arc voltage being too low to trigger the GDT.

author: bastl_r
author_rank: Regular Contributor
timestamp: November 14, 2022, 09:41:45 pm
content: The folllowing video shwos what hapen when a 100000µF 700VDC capbank will be discharged on a low price Multimeter. The last one is complete without a fuse.And this is what hapen when the discharge blow a Fluke fuse

author: Gyro
author_rank: Super Contributor
timestamp: November 14, 2022, 10:11:59 pm
content: A good demonstration of arc flash - although the meters seem to fly apart too quickly to sustain a flame arc! A big shrapnel field though. Probably penetrating wounds rather than burns.That test setup looks pretty dodgy for that amount of store energy though.