BEWARE the price of  some Fluke fuse replacement . - Page 1
Forum section: electronics / general

author: Kevin.D
author_rank: Frequent Contributor
timestamp: May 26, 2012, 08:45:20 am
content: I just want to post here to complain about the price of fuse replacement's here forFluke meters that have the ceramic cooper bussman fuse's. I recently bought a Fluke 177 . I haven't used it much yet (and wont be using again for current measurement grrrr) . First time I used it for measuring current on a panel and SMALL current surge from some cap charging and BANG your 440ma fuse blows, yes very easily done and normally with my Metex meter no big deal just replace a 10 cent fuse ,BUT not with a Fluke no, when you go to buy the fuses for Fluke the cheapest you can get them here in the UK is £5 EACH !!! . 2 more very simple mistakes and £15 down and no more using a Fluke for current measurement for me .!!!

author: chrome
author_rank: Regular Contributor
timestamp: May 26, 2012, 09:44:23 am
content: So you expected a reasonably expensive meter that has very high standards towards not blowing up in your hands thanks to good protection to have a cheap fuse?

author: SeanB
author_rank: Super Contributor
timestamp: May 26, 2012, 09:56:14 am
content: Met that before, and looked online and bought a box. Works out to the price of 4 fuses, and you get 10.What do you want, a cheap fuse that arcs if you are accidentally connecting it across the mains and the carry current blows up your meter, or a fuse that will break that safely.

author: Kevin.D
author_rank: Frequent Contributor
timestamp: May 26, 2012, 10:12:37 am
content: Say what you want, I would never recommend any meter that has such expensive fuses for low power electronics work .This meter is advertised as "general purpose" suitable for electronics and low power work . I have been using my Metex and Agilent meters for 25+ years and never had one "EXPLODE" on me . IF it's going to cost me £5 quid every time I make a small error then I'm sorry but that's crap ..

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: May 26, 2012, 10:18:11 am
content: Quote from: kevotronic on May 26, 2012, 10:12:37 amThat's just the price of the Fluke's CAT<whatever> safety. There's nothing stopping you soldering a small wire across the caps of a dead Fluke fuse if you know for absolute certain it will never be connected to anything with enough energy to burst the case.

author: SeanB
author_rank: Super Contributor
timestamp: May 26, 2012, 10:25:58 am
content: You must know our council sparkies then........ I saw where one tried to measure the voltage on a 11kV cable, and the only thing that survived was the fuse, the battery and the LCD display. Probes were vapourised along with the meter main board. Even the case was burnt, and copper plated.

author: Unknown
author_rank: Unknown
timestamp: May 26, 2012, 10:31:59 am
content: All decent meters designed for mains circuits (CAT II+) will have HRC fuses. Agilent uses fuses with an even higher interrupt current rating in their U125x series, not sure about the costs. If blowing fuses is a common occurrence for you, you may try to be more careful. I think I've only blown a few multimeter fuses in the past few years. I will usually start with the 10 A range if I'm not sure about the current, and I won't measure current between two points without understanding the circuit.Quote from: mikeselectricstuff on May 26, 2012, 10:18:11 amIf you're going to defeat safety features, make sure to put a big orange warning label across the front indicating never to use them for high energy circuits. Having a meter marked as CAT III 600 V with a fuse replaced by a wire is very dangerous in my opinion. I recently came across a report from someone that had bought an expensive multimeter (used). The input circuitry was destroyed because the previous owner had replaced the fuse with a piece of aluminum foil. I'm quite sure the damage exceeded £5.

author: eevblogfan
author_rank: Frequent Contributor
timestamp: May 27, 2012, 01:41:17 pm
content: why dint you make you're own current shunt ? ,for unknown current value's circuit , I uses my 1mohm 50A shunt (I've made and calibrated) , with regular 200mV range you can measure down to 0.1A , that will give you indication of the current flow , : lower then 400mA - use the 400mA shoket , higher ? -use the 10A ,note , building you're own shunt and using him without fuse/fused leads . is absolutely dangerous !!!another tip , you can always use an external CC circuit with series , in order to not allow current > then 400mA , then you can even build , over current circuit . and you'll have no need in replacing the fuse every time you've done a mistake ( ie , connecting the whole setup to mains- mosfet : explode/dead short-> ocp fail->then the expensive fuse save you injuries and burns)

author: Monkeh
author_rank: Super Contributor
timestamp: May 27, 2012, 02:04:14 pm
content: If you want a meter with cheap fuses, get a UT61E. They use BS1362 fuses. Ten a penny, and more than adequate for electronics work (don't try 200VDC 10A unless you're very, very sure you know what you're doing, but..).

author: grenert
author_rank: Frequent Contributor
timestamp: May 27, 2012, 02:21:02 pm
content: This is like the Ferrari owner complaining about the cost of tires for his car, even though he only drives to church, under the posted speed limit.

author: T4P
author_rank: Super Contributor
timestamp: May 27, 2012, 02:30:28 pm
content: Quote from: Monkeh on May 27, 2012, 02:04:14 pm... Of course not, but to be sure a owner is dumb if he uses glass fuses (BS1363) ...I use cooper bussman fuses to replace it 6kA so i'm not worried and i have never seen a ceramic fuse on consumer equipment blow it's body apart from 13amps (apart from having seen it get so hot slowly until the fuse terminals melted a hole ... that was a cheap ceramic fuse)

author: Monkeh
author_rank: Super Contributor
timestamp: May 27, 2012, 02:39:41 pm
content: Quote from: DaveXRQ on May 27, 2012, 02:30:28 pm.. BS1362fuses are sand-filled ceramic fuses with a breaking capacity of 6kA, and are what the UT61E is supplied with.

author: T4P
author_rank: Super Contributor
timestamp: May 27, 2012, 02:41:44 pm
content: Quote from: Monkeh on May 27, 2012, 02:39:41 pmI know i know, but that's safe for 250V i assume ?

author: Monkeh
author_rank: Super Contributor
timestamp: May 27, 2012, 02:43:07 pm
content: Quote from: DaveXRQ on May 27, 2012, 02:41:44 pm250VAC. As I said, you'd best know what you're playing at if running high DC voltages through an AC rated fuse.

author: SeanB
author_rank: Super Contributor
timestamp: May 27, 2012, 03:06:18 pm
content: Yes, compare that the same fuse will have a voltage rating of 250VAC and 32 VDC.

author: Monkeh
author_rank: Super Contributor
timestamp: May 27, 2012, 03:11:55 pm
content: Quote from: SeanB on May 27, 2012, 03:06:18 pmRealistically a BS1362 fuse is probably fine at much higher voltages than that, both AC and DC, but they're only officially rated for 250VAC (there is no official rating for DC. The manufacturer may test and rate for DC themselves, however).However, 32VDC is quite a lot for most electronics work.

author: Unknown
author_rank: Unknown
timestamp: May 27, 2012, 03:20:11 pm
content: I would expect a DMM rated for CAT II 1000V to also be safe with 1000 VDC at some fairly low output impedance. I remember Uni-T arguing something different when someone complained about the 250 VAC fuses in one of their meters, which means that they apparently consider it OK for their equipment to blow up in your face if you severely overload the current input (expect it to conform to IEC 61010 like the voltage input).Quote from: Monkeh on May 27, 2012, 03:11:55 pmThat's not how safety margins work in engineering. You design a circuit for 200 VAC max, and you might specify 250 VAC fuses. The fuse manufacturer might design their fuses specified for 250 VAC to withstand 300 VAC. Together, this makes it very unlikely for your circuit to fail at 200 VAC, and gives it a chance to survive overloads well beyond 200 VAC.

author: Monkeh
author_rank: Super Contributor
timestamp: May 27, 2012, 03:25:25 pm
content: Quote from: alm on May 27, 2012, 03:20:11 pmSo why did we have a 250VAC rated fuse designed for 250VAC circuits?

author: Unknown
author_rank: Unknown
timestamp: May 27, 2012, 03:42:28 pm
content: A designer might elect to do without safety margins and rely on the fuse manufacturer. This is quite different from assuming that 250 VAC will probably handle much more than 250 V. Most of the circuits using 250 VAC fuses are 230 V or 240 V, although the recent discussion about 240 V in Oz sometimes being 253 V highlights the importance of safety margins. If the nominal voltage already exceeds the rated voltage, what do you expect to happen in the case of an overload/transient?

author: Monkeh
author_rank: Super Contributor
timestamp: May 27, 2012, 03:51:58 pm
content: Well, I'm not going to argue about it, just giving my two 'cents' based on using these fuses for my entire life.You should be aware that every single rating you see on electrical installations here has a fair safety margin, unlike designs from certain countries.

author: T4P
author_rank: Super Contributor
timestamp: May 27, 2012, 05:52:35 pm
content: If i am indeed that worried i may as well desolder the fuse holders and put in HRC fuse holders since the footprint is already there