Small DMM fuses
 

Having enjoyed the (recently closed) thread in this section on buying a multimeter, I made a first purchase from AliExpress.
I chose a recommended supplier of the BSIDE ZT101 and it arrived in 7 days with very good tracking. I has 6000 count and does True RMS, capacitance, etc.
What I neglected to research was the size of the internal fuses in that model. They are only 10mm long by 3.6mm diameter ceramic. Two of my other DMMs regularly blow their fuses (wasn't me guv) so I keep a stock handy - but I have not located a UK supplier of these tiny fuses - in fact I only found one source on AliExpress.
Has anyone here bought these fuses? You do not have to confess to actually using them...

Re: Small DMM fuses
 

I had a look at the AliExpress site on this meter and one thing came to mind- from their product use- WHY would anyone want to test the current of a battery? And I'm not really impressed with the other product use ideas. But then in my dotage, I'm a converted Fluke user.
However, you do not quote the fuse value . But on a quick google, I found these on Amazon (https://www.amazon.co.uk/s/?ie=UTF8&...l_9s2if34aql_b)

And here -https://www.alibaba.com/showroom/10mm-fuse.html
And a lot more on a google "10 mm fuse".

Re: Small DMM fuses
 

Sorry, I should have mentioned the fuse values - 600mA and 10A.
I also omitted to say that I had tried google but all I was getting were the wire-ended type which seem to include end caps so would not fit the fuseholders. I am assuming that the end caps are fixed to the fuses and are not removable but not having used one I can't be certain.

I will study the urls you kindly provided later after chores finished.
Thanks.

Re: Small DMM fuses
 

Not sure I like those fuses, they don't offer much protection to you or your meter. I see there are no PTC's (unless their on the other side) or spark gaps, just those big 5M R's. If it were mine I'd be tempted to replace the fuse holders to accept a normal 3/4" fuse, It looks like there's room to move one post back behind those black screws.

I'd be wary of using your DMM on the mains, is it CAT rated at all? Lastly if you get a chance and a spare £30 try and get a Fluke 25, they have proper protection and survive numpty's trying to measure 600v while on the ohms range. After buying a few meter's and killing them it was the best thing I did. They don't measure capcitance but you can test caps with the DC resistance with a bit of experience.

Sorry for the hard sell on the Fluke, there is a good reason though, why a lot of folk swear by them. They accept standard fuses for one.

Andy.

Re: Small DMM fuses
 

This meter (well, the near-identical ZT-102) has survived high voltage transients which damaged the Fluke 87V - search YouTube for Joe Smith's tests. So although I'd be the first to say that the CAT ratings are fictitious - as is the case for most cheap (and some not-so-cheap) multimeters - I'd not be too concerned about using the meter to measure mains on the bench. But not in the consumer unit though ;)

There is a PTC, only it's not visible in the supplied images. I've got more detailed images on my review.

I agree the fuses are a minor pain. The manual says that you mustn't measure current in situations where more than 32V DC could exist which, when you read between the lines, is a tacit admission that these fuses won't necessarily open safely at higher DC voltages. The fuses themselves are rated at 250V AC, but obviously interrupting DC is another matter.

Although I have several of these meters, I still haven't got around to buying spare fuses. A lot of folk on the EEVblog forum have bought wire-ended fuses and chopped the wires off - I've not read of any issues with fit, in terms of diameter. I see that Farnell stock suitable fuses with no wires to cut off, but they are "while stocks last". RS and Farnell appear to have plenty of the versions with wires, but mostly appear to have the "bump" caused by the end caps that you mention - but the Littlefuse 776 series appear to be a better fit, so that'll be worth investigating...

The BSIDE ZT301 that I mentioned a few times in that recent thread uses conventional 20mm fuses. They come with ceramic types. The AN860B also uses 20mm fuses, but the ones in my sample are glass - I recommend changing those for ceramic fuses.

Overall, I wouldn't say that Fluke fuses are any more "standard" than the 10mm jobs found in the ZT101. A lot more expensive though. A pair of fuses for a Fluke won't leave much change from £20 if you buy them from a reputable supplier. They are widely faked, so avoid the eBay ones. Looking just now, I note that the prices from RS and Farnell are a bit less than the last time I bought some, so that's a step in the right direction.

I've only ever blown a multimeter fuse once. It was the 440mA one in my Fluke 189, and it was in a pretty benign scenario - these fuses are very fast acting. I had a bit of a shock when I looked up the price of the replacement, and that was all the motivation I needed to be extra-careful when using Flukes! That was more than 10 years ago, I'm proud to say ;)

Re: Small DMM fuses
 

"This meter (well, the near-identical ZT-102) has survived high voltage transients" surprising, there's not much there in way of protection, unlike an old Fluke.

Good point about Fluke fuses being expensive but at least they are proper safety fuses. How can a 10mm diddy fuse stop arching and blowing itself to bit's?

I blow the little fuses in my Fluke quite often. they're rated at 630mA, which is a daft figure. If your measuring a DUT a current surge at SW on can go over that , why not make it an amp?

I probably overly dissed the ZT101 and it's fuses Mark, should have done my research instead of judging a book by it's cover. Still don't like the diddy fuses though, might as well use fuse wire : )

Andy.

Re: Small DMM fuses
 

Don't worry - you know that I'm a bit of a Fluke fanboy ;)

Unlike some, I would never want to dissuade someone who could afford to buy a Fluke or Keysight from doing so - they are good meters and there are real benefits to owning them. But not everyone can afford or justify buying an expensive meter - which is absolutely fine providing they are aware of the potential risks. As a result, I've made it a sort of mission to try to spread as much information about cheap multimeters as I can, so that folk can make an informed decision about what to buy, and how to use them safely.

Key to this message is understanding that the most important aspect of multimeter safety is the user, not the meter. After all, it's possible to kill yourself while using the safest meter in existence. Indeed, using a meter that has a strong reputation for safety can cause a false sense of security.

The functionality of these cheap meters is astonishing for the money, but I agree that the 10mm fuses don't exactly inspire confidence. Keep them away from high-energy situations and they will be absolutely fine. I use them as much as Flukes and so far, so good :thumbsup: