Hi,

I'm trying to replace a cartridge fuse in my multimeter but I cannot find a 5x20mm with the same 10a 700v configuration. I've attached a photo of the fuse that came with the multimeter. I've scoured the internet and Amazon but all of the 10 amp 700 volt seem to be the 5x32 size. Any suggestions on where I could find one of these or should I just go to a 10 amp 250 volt? I'm not a very skilled electronics person but mostly using this multimeter to test 12 volt projects.

 

Welcome to AAC!

What brand of multimeter? 700V is a bit odd. Lots of 5x20 250V & 500VAC but not 700? There may be more specifications to it other than just the voltage and amps. If you are not measuring anything greater than 220VAC a 250V should do in a pinch. The fuses for my Flukes are custom made just for Fluke so not outside sourced.

 

Welcome to AAC!

What brand of multimeter? 700V is a bit odd. Lots of 5x20 250V & 500VAC but not 700? There may be more specifications to it other than just the voltage and amps. If you are not measuring anything greater than 220VAC a 250V should do in a pinch. The fuses for my Flukes are custom made just for Fluke so not outside sourced.

Thanks Sam, The MM is an Amazon cheapO, Tack Life. (Photos Attached) Yes, I was thinking a 250v should be ok so I appreciate your suggestion.

 

One more question. Does it matter if it's a glass fuse or does it have to be a ceramic like my original fuse?

 

I'm not familiar with the 5.700 marking on the fuse? Are there any other markings? I would suggest a 250V Ceramic fast acting 10A replacement in a pinch. There are no fuse specs in the manual and it simply states replace with same. The meter does have a 600V Range so the fuse was rated for 700V @ 10A. With a 250V rated fuse, use over that voltage could possibly cause arcing across the fuse. So, I would limit usage to 250V or less without the properly rated fuse. Ceramics are used to prevent rupture and blowout when the fuse is blown. You might try contacting Tacklife for a correct fuse replacement source. That is not a standard use fuse.

 

Are you sure it is a 5x20???

 

RS do them .
https://uk.rs-online.com/web/p/cartridge-fuses/0563592

 

A ceramic fuse is generally (but not always) filled with sand to quench the arc.

RS do them .
https://uk.rs-online.com/web/p/cartridge-fuses/0563592

That's only 250V.
The fuse is in the current measuring circuit. It is there in case the probe gets left in the 10A socket when measuring a voltage.

 

I’ve got myself a bit of a reputation at work for blowing fuses in Fluke multimeters, normally the one protecting the 400mA range. It’s not through having the meter leads connected across a mains supply or other voltage (with the leads in the current sockets), but through not knowing that the resultant measured current will significantly exceed the meter’s fuse rating.

The fuses are quite expensive (more than £10 a go), the reason for this (besides them being bespoke to Fluke) is that they are high rupture capacity (HRC) types with a breaking capacity of 1500A, but they are also rated to 1,000V. The reason that they need this rating is that should the meter be connected across a voltage at the maximum rating of the meter (1,000V), and accidently on the current range (then the fuse needs to withstand the fault current from this circuit at 1,000V).

So fuses protecting a multimeter should have a voltage rating matching the maximum voltage measurement of the meter, and be HRC types.

 

rated voltage is proportional to distance between fuse terminals and everyone making 5x20mm fuses gets them only rated to 250V. i seriously doubt the fuse marking is correct but will accept it if there is a part number and UL/CSA file number of the product. until then i would say the marking is fake. it would not be the first time some cheap product was made using fake parts or has fake approvals.

 

You can buy the weird Fluke fuses from Mersen - part number FSM44/100. They are listed as “multimeter fuse”. I bought a box of 10, but now if I’m going to measure the current into anything with the slightest risk of a large inrush current I find a shunt and measure the voltage across it.

 

I too had a meter with ceramic fuse (in my case 1A, but also had 10A). Could not find in US. Ended up going on eBay and fuse was shipped from China. Seems like these fuses are common in Europe and are inside plugs and such. Measure existing fuse carefully.

After further looking you should probably go with F10AL250V ceramic or glass at 250V should be found Amazon, eBay, etc

Then there is Eaton/Bussman that make a 5mmx20mm glass fuse (GDB-10A) available from Mouser or DigiKey but they cost much more.

 

5x20 F10A ceramic fuses are easy to find, but not in 700V? Seems they have to be longer to meet the higher voltage rating and 600V fuses are 6x32 mostly. Never did find a small 700V, it's just a weird value and not a common item. Unfortunately, their manual has no true fuse specs or part numbers and simply states replace with like kind. Which is why I ask if it is really a 5x20? Looking at the picture, it seems a bit long for 20mm.

 

5x20 F10A ceramic fuses are easy to find, but not in 700V? Seems they have to be longer to meet the higher voltage rating and 600V fuses are 6x32 mostly. Never did find a small 700V, it's just a weird value and not a common item. Unfortunately, their manual has no true fuse specs or part numbers and simply states replace with like kind. Which is why I ask if it is really a 5x20? Looking at the picture, it seems a bit long for 20mm.

Yes, it is 5x20mm for sure. I've taken the approach of 10a250v for now as I'm only testing low voltage with this so should not be a problem. I really appreciate your help, Sam.

 

rated voltage is proportional to distance between fuse terminals and everyone making 5x20mm fuses gets them only rated to 250V. i seriously doubt the fuse marking is correct but will accept it if there is a part number and UL/CSA file number of the product. until then i would say the marking is fake. it would not be the first time some cheap product was made using fake parts or has fake approvals.

This is most likely the problem. Thanks so much for this fuse education. I'm going with a 10a240v, for now, to make it easy to replace. And I only use this MM for 12v projects so it should be fine.

 

You can buy the weird Fluke fuses from Mersen - part number FSM44/100. They are listed as “multimeter fuse”.

why weird? it is a very common "midget" fuse. (simple barrel 10mm x 38mm)
it is pretty much the same size as CC Type but not keyed - on CC Type one end has a step.
unlike CC type, midget fuses are defined as supplemental protection and are not rated for current limiting. that is the reason for special shape of the CC fuse so that midget will not fit into CC fuse holder but CC will fit into midget holder.

CC fuses are produced in high volume for industrial applications. price per piece is usually $3-5, and should be cheaper when buying 10pack.

as mentioned midget and CC type are much larger than 5x20mm
Littlefuse series 487 is 5x20mm product that is rated up to 420VAC.
https://www.littelfuse.com/products/fuses/cartridge-fuses/5x20mm-fuses/487.aspx

i thought the 5700 in picture in original post may be referring to interrupting capacity or maximum fault current (5.7kA). but that too dos not seem right. any product from reputable manufacturer list much lower value for this fuse form. (300A or so). to be in kA range this would need to be at lower voltage (125V or so). it would be nice to find out exact part number, manufacturer and check UL/CSA listing that this product claims to have.

 

I saw it as 5.700 and wondered if it might be Ω as some fuses are additionally rated for resistance and available with different resistance values at the same V and I rating.

 

why weird? it is a very common "midget" fuse. (simple barrel 10mm x 38mm)

Fluke fuse on the right, standard 10x38mm fuse on the left.

A 10x38mm can just be persuaded into a Fluke meter.

And isn’t 440mA weird? What’s wrong with 0.5A, surely the extra 60mA isn’t going to wreck the meter?

 

Never noticed the length being different than standard but 440mA is definitely weird! After you blow it the first time and try to find a replacement you learn to keep a few in stock.

 

good to know, never blew mine and would not like to get stuck