Products > Test Equipment
Multimeter fuses
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joeqsmith:

--- Quote from: helius on July 13, 2016, 01:03:41 pm ---It's slightly overstating it to say the fuse is only for when you misuse the meter. If the power-consuming circuit element that you are measuring current for were to fail short, then the meter itself would become the driven device; the fuse protects you from that situation, too.
For example, you are using the DMM in amps mode to measure the performance of a dummy load connected to a 1KW supply. What happens when the load fails short?

--- End quote ---

There are shitty glass fuses then there are HRC fuses.   Both can protect the meter from damage.    Seeing you're providing example, for your 1KW supply assuming it is a 100,000V,  my guess is the meter would lug down the supply.  I guess you could try it and post your results. 


--- Quote from: Berni on July 13, 2016, 12:50:22 pm ---The question is if a DIYer does the same amps jack mistake in his home mains distribution panel. Could a cheep meter and fuse become more dangerous in such a situation versus a HRC fuse?

I personally never have taken care of using only good quality meters on regular household 230/400V mains. I picked up whatever meter was handy, be it my good Agilent or the cheap 20€ rebadger.

--- End quote ---

I am not sure what a worst case number would be for how much energy you could have across the incoming lines to your house.   :-//   I have seen some meter's cases open up and others with sparks coming out and even some leads that ruptured with some fairly low energy transients. 

I would not be too surprised if some of the meters I looked at could have a fair amount of damage in the current settings, even with the fuses removed.   

Too many variables.   But I would be very interested if you come up with some sort of test and run it. 
Fungus:

--- Quote from: helius on July 13, 2016, 01:03:41 pm ---For example, you are using the DMM in amps mode to measure the performance of a dummy load connected to a 1KW supply. What happens when the load fails short?

--- End quote ---
You need a fuse, sure, but does it need to be one of those expensive Bussman fuses? A simple glass fuse can interrupt 1kW.

The Bussman fuses are for situations where there's thousands of amps available, where a glass fuse will turn to metal vapor inside the tube.
MacMeter:

--- Quote from: iXod on July 06, 2016, 09:27:29 pm ---11A fuse for EEVblog BM235: US$41.00. Not for a box of 5. Each.

http://www.digikey.com/product-search/en?keywords=DMM-B-11A

Next meter, Dave, use tin foil! lol

Can't imagine Bussmann's justification for such a price. Is it that much quicker than other fuses? Gold filament?

edit:
Digikey offered this as alternative:

http://www.digikey.com/product-search/en?keywords=614-1078-ND

All but the "B" in the pn... and US$9.

Good alternative?

Cheers.

--- End quote ---

I've just run into this dilemma, I was shocked to see the large fuse costing 1/3 the price of the meter.

There are a few threads here about this, and I posted the same request (below) in case anyone reads those old threads. Seeing such a price decrepancy made me realize the fake/clone market For these is a real concern. I'm not going to get into the debate if "similar" fuses are ok, or good enough. In my use, there are times I might rely on them, so I'd like to find the original spec'd fuses at a reasonable price, if that's even possible?

Anyone find a reputable online company, (I'm in the US) that sells both types of replacement fuses at reasonable prices? BM235 model.

I looked at both Mouser, and GreyBar, both large companies, but a single large fuse is over $40/each, and of course I can find them on eBay, for far less, but I have no idea if they are Chinese clones, since China is the source. The price range between them is crazy, 3 large fuses cost as much as the base meter. THANKS!
joseph nicholas:

--- Quote from: Berni on July 13, 2016, 12:50:22 pm ---
Voltage overloads in s are usually not as concerning since you rarely encounter more than 1000V at home and if you do it tends to be low current. So as long as you don't try to measure the output of a microwave oven transformer you should be safe.


--- End quote ---

Measuring this voltage I just use my cheap chinese MF-47 multimeter.  It goes up to 2.5KV.  It also has a seperate jack for this measurement so its hard to fuck it up.
mmagin:
It may be bad luck saying this, but I've not yet blown a fuse in a DMM.  I've actually destroyed the tip of one of the probes that came with my Fluke 179 though.
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