“Blown” Fuses in Several New Multimeters

[Locator]

I’ve run across something that is very perplexing to me. The other day, I accidentally checked 110v AC house voltage with my Fluke 117 on the AC current setting. Of course, the outlet sparked and it slightly damaged the tip of the probe. The multimeter did not turn off, but I thought I probably blew the fuse… Only time I’ve ever done this, but it was a moment of getting distracted and I kicked myself for getting distracted….

I opened it and tested continuity on both fuses. One of them did not work with continuity and also showed “OL” when checking resistance. Both tests were done with a brand new Fluke 179. Okay, I suppose I need to order a fuse from Fluke (I’m assuming 110v AC will blow the 10a fuse?)

Then, just out of interest, I then opened up the brand new Fluke 179 and tested both fuses in the 179 (out of the meter). One of them was open - no continuity. (Checked with a new Fluke 87V.) What?? This was a brand new meter and the only thing I tested with it, for function was continuity, the resistance of the leads, a couple of AA alkaline batteries and the AC house current. IN the AC voltage setting - NOT in the current setting. I wondered if maybe it was a return to Amazon and someone else blew the fuse and sent it back, I don’t know.

Then, for fun, I checked the 87V. both fuses showed continuity.

Then, I checked two Brymen 257’s (actually, Greenlee DM-510a’s). Both fuses were okay in these.

Then, I opened a Brymen 827 (it was a Greenlee DM-830a) and the larger fuse was open - no continuity. I purchased this new from Amazon a few years ago and it has led a pampered life - barely used. And, never any current. It was only tested with continuity with the leads a few years ago and kept in the case.

Now, I had a couple of fuses on the workbench that I took out of a dead Klein MM6000 I had for years. It also had a pampered life and had only checked continuity a handful of times and the resistance of the leads. I took it out of the case a few months ago and the display was dead. I figured it was because it was a Klein, as I have had two other Kleins die a long time ago. I removed the two fuses - 1000v and 600v and kept them for spares. I checked them for continuity after doing all the other checking and BOTH of them were open. No continuity. Checked with a perfect Fluke 87V.

And last one - I have an Amprobe AM-570, that I also bought new (all of these meters were bought new). It has only checked DC voltage and continuity. Also used it to check 110v house AC to check its’ accuracy compared to the Flukes. BOTH of its’ fuses were open - no continuity.

Any thoughts on how I ended up with all of these dead fuses? They are all the factory fuses that came in the new multimeters and the only one that I evidently damaged was the Fluke 117. These things are the poster children for perfect condition multimeters.

I know it sounds like these meters have been in the hands of a careless user, but they’re hardly used and I am the only one that has touched them.

Shouldn’t ALL fuses in multimeters show continuity when tested?

[Jeroen3]

Did you do this with the wires you used to measure 120V of AC current? Because I've seen flimsy wires get damaged by it.
Genuine fluke wires   probably   not, but you should check anyways.

_{(I've also evaporated the probes once with exactly the same mistake as you, only on a bigger socket, not fun)}

[wraper]

Then, just out of interest, I then opened up the brand new Fluke 179 and tested both fuses in the 179 (out of the meter). One of them was open - no continuity. (Checked with a new Fluke 87V.) What?? This was a brand new meter and the only thing I tested with it, for function was continuity, the resistance of the leads, a couple of AA alkaline batteries and the AC house current. IN the AC voltage setting - NOT in the current setting. I wondered if maybe it was a return to Amazon and someone else blew the fuse and sent it back, I don’t know.

Do you mean you tested AC voltage? Selected switch position does not matter for this. If the probe was plugged into 10A or 400mA socket, it will blow the fuse.

[Fungus]

Meters don't have to be in "amps" setting to blow a fuse.

It's enough just to have the cable in the "A" connector when you try to measure voltage.

You don't need voltage to blow a fuse, just amps. You can blow a fuse with 1V if there's enough amps.

[Locator]

Did you do this with the wires you used to measure 120V of AC current? Because I've seen flimsy wires get damaged by it.
Genuine fluke wires   probably   not, but you should check anyways.

_{(I've also evaporated the probes once with exactly the same mistake as you, only on a bigger socket, not fun)}

If you mean, did I test each of the fuses with the damaged leads, no - they were set aside so I could clean them up, later. The tests were done by two different sets of Fluke silicone-insulated leads that I had ordered to replace the factory leads that come with the multimeters.

[Locator]

Then, just out of interest, I then opened up the brand new Fluke 179 and tested both fuses in the 179 (out of the meter). One of them was open - no continuity. (Checked with a new Fluke 87V.) What?? This was a brand new meter and the only thing I tested with it, for function was continuity, the resistance of the leads, a couple of AA alkaline batteries and the AC house current. IN the AC voltage setting - NOT in the current setting. I wondered if maybe it was a return to Amazon and someone else blew the fuse and sent it back, I don’t know.

Do you mean you tested AC voltage? Selected switch position does not matter for this. If the probe was plugged into 10A or 400mA socket, it will blow the fuse.

I had the red lead plugged into the 10A port and the black lead plugged into COM on the 117, when it happened. The setting on the dial was set to “A” for AC Amps. What happened was, I had just checked current before this and then went to check voltage on this outlet. I accidentally left the leads in the current ports and the dial on “A” (AC Amps). I inserted the probes into the 120v socket without thinking about the mixup. I shouldn’t have been juggling two things at once - I knew better than that, but just got distracted and in a hurry.

[Locator]

Meters don't have to be in "amps" setting to blow a fuse.

It's enough just to have the cable in the "A" connector when you try to measure voltage.

You don't need voltage to blow a fuse, just amps. You can blow a fuse with 1V if there's enough amps.

Yep, this was exactly my mistake. I may have mixed up some of the details in my long OP diatribe, but the dial was on “A” and the red probe was plugged into the 10A current jack and I “tested” voltage on the outlet. (Good grief, every time I think about it, I could kick myself. And on a new meter, too.)

[Phil1977]

There are two types of DMM users - these who have connected voltage to the current input and those who will.

[modoran]

.. and those who just doesn't have any current jacks on their DMM at all or never changes the leads position.

[Gyro]

With due regard for your history in hazardous CRT TV repair...

Never poke standard DMMs into mains outlets, fuseboards etc. Firstly there's nothing to see there that is interesting enough to justify their resolution, and secondly, they are not intrinsically safe (read idiot proof - we are all idiots waiting to happen). Use Electrician's tools.

In this case, you want a 2 pole voltage tester (not one of those crappy single pole or non-contact ones). I don't have visibility of what is commonly available in the US, but in the UK you would use something like the Martindale VT25, Kewtech KT1710 (or KT1780 if you must have a digital display). Fluke T5 etc.

They are 'idiot proof' - no switches, no sockets, no fuses, they still give a voltage indication if the battery is flat or missing, and have safe continuity test. Above all, they have high CAT ratings for far less cost than the equivalent DMM. Ideally get a proving unit too, or at least, test on known live, before and after checking the circuit.

[indman]

There are two types of DMM users - these who have connected voltage to the current input and those who will.

I can add one more mandatory step, which is usually done after purchasing a DMM - measure the strength and power of the current in a ~220V/110V outlet!

[Fungus]

Meters don't have to be in "amps" setting to blow a fuse.

It's enough just to have the cable in the "A" connector when you try to measure voltage.

You don't need voltage to blow a fuse, just amps. You can blow a fuse with 1V if there's enough amps.

Yep, this was exactly my mistake. I may have mixed up some of the details in my long OP diatribe, but the dial was on “A” and the red probe was plugged into the 10A current jack and I “tested” voltage on the outlet. (Good grief, every time I think about it, I could kick myself. And on a new meter, too.)

Yes, we understand this incident. I'm referring to all those other fuses...

[Fungus]

Never poke standard DMMs into mains outlets, fuseboards etc. Firstly there's nothing to see there that is interesting enough to justify their resolution

Agree.

and secondly, they are not intrinsically safe (read idiot proof - we are all idiots waiting to happen). Use Electrician's tools.

Plug in a lamp, it tells you just as much info.

[wraper]

In this case, you want a 2 pole voltage tester (not one of those crappy single pole or non-contact ones). I don't have visibility of what is commonly available in the US, but in the UK you would use something like the Martindale VT25, Kewtech KT1710 (or KT1780 if you must have a digital display). Fluke T5 etc.

They are 'idiot proof' - no switches, no sockets, no fuses, they still give a voltage indication if the battery is flat or missing, and have safe continuity test. Above all, they have high CAT ratings for far less cost than the equivalent DMM.

I'd never waste money on that overpriced garbage that cannot display the voltage with remotely reasonable accuracy. There is nothing wrong with using multimeter as long as you know what you're doing. IMHO those testers are for people who don't know one's head from a hole in the ground. Not to say for that money you can buy a quite decent multimeter with similar CAT rating. Heck, if you cannot plug the leads into proper terminals to save your life, cover amps sockets by sticky tape.

[wraper]

Use Electrician's tools.

Fluke 117 is literally an "Electricians Multimeter" https://www.fluke.com/en/product/electrical-testing/digital-multimeters/fluke-117

[Gyro]

In this case, you want a 2 pole voltage tester (not one of those crappy single pole or non-contact ones). I don't have visibility of what is commonly available in the US, but in the UK you would use something like the Martindale VT25, Kewtech KT1710 (or KT1780 if you must have a digital display). Fluke T5 etc.

They are 'idiot proof' - no switches, no sockets, no fuses, they still give a voltage indication if the battery is flat or missing, and have safe continuity test. Above all, they have high CAT ratings for far less cost than the equivalent DMM. Ideally get a proving unit too,

I'd never waste money on that overpriced garbage that cannot display the voltage with remotely reasonable accuracy. There is nothing wrong with using multimeter as long as you know what you're doing. IMHO those testers are for people who don't know one's head from a hole in the ground. Not to say for that money you can buy a quite decent multimeter with similar CAT rating. Heck, if you cannot plug the leds into proper terminals to save your life, cover amps sockets by sticky tape.

Plug in a lamp, it tells you just as much info.

Sorry, we're going to have to disagree on this one. Yes a lamp is intrinsically safe... as long as you test it on a known good circuit before and after plugging it into suspect circuit.

As far as the testers, they are there to protect life against itself. DMMs (as the OP has demonstrated) have far too many opportunities of error. As I said, we are all idiots waiting to happen!

[Fungus]

Plug in a lamp, it tells you just as much info.

Sorry, we're going to have to disagree on this one. Yes a lamp is intrinsically safe... as long as you test it on a known good circuit before and after plugging it into suspect circuit.

That's true of multimeters as well.

It's why they sell these: https://www.fluke.com/en/product/electrical-testing/basic-testers/prv240-proving-unit

Without one of those your meter/lamp can only indicate the presence of voltage, not absence.

[Gyro]

Use Electrician's tools.

Fluke 117 is literally an "Electricians Multimeter" https://www.fluke.com/en/product/electrical-testing/digital-multimeters/fluke-117

As in marketing speak for a bunch of features useful for a commercial electrician and  decent CAT rating. It won't tell you that you are testing whether a circuit is live with the probes in the A jack and the dial set to Volts. It won't blow up in your face but it is not intrinsically safe in proving a circuit dead, i.e. If somebody dies from touching a live circuit, it won't be deemed adequate in court, non-contact test is unreliable. I'm veering towards commercial installations at this point of course.

Read any of the manufacturers sheets (including Fluke) on safe isolation.

[Fungus]

As in marketing speak for a bunch of features useful for a commercial electrician and  decent CAT rating. It won't tell you that you are testing whether a circuit is live with the probes in the A jack and the dial set to Volts.

Doesn't the Fluke 117 have input jack alert? If it doesn't then it should be kept away from mains AC.

Me? I think the only "electricians meter" made by Fluke is the 113.

[Gyro]

Plug in a lamp, it tells you just as much info.

Sorry, we're going to have to disagree on this one. Yes a lamp is intrinsically safe... as long as you test it on a known good circuit before and after plugging it into suspect circuit.

That's true of multimeters as well.

It's why they sell these: https://www.fluke.com/en/product/electrical-testing/basic-testers/prv240-proving-unit

Without one of those your meter/lamp can only indicate the presence of voltage, not absence.

Yes,. Those proving unit's (that I mentioned) are sold for pre-post checking two pole testers as part of the standard safe isolation procedure. Unfortunately they won't power your lamp, hence you have wander off with it to find a live outlet. The sequence is... prove that the tester detects live voltage before, test the circuit and ensure that it reads dead, test the tester again to check that it didn't go faulty in the meantime. You can only assume that the tester worked last time, hence you need to check it again afterwards.

[Gyro]

As in marketing speak for a bunch of features useful for a commercial electrician and  decent CAT rating. It won't tell you that you are testing whether a circuit is live with the probes in the A jack and the dial set to Volts.

Doesn't the Fluke 117 have input jack alert? If it doesn't then it should be kept away from mains AC.

Me? I think the only "electricians meter" made by Fluke is the 113.

No, I can't see input jack alert in the specs (Unless I missed it). It just has things like Lo-Z volts to avoid ghost voltages, non contact volts (insufficient for safe isolation), Auto AC/DC volts (useful, checking an AC circuit on DC range is another accident just waiting to happen!). But certainly too many gotchas to consider it anywhere near intrinsically safe (for anything other than not blowing up in your face). Basically, it still relies on you not being an idiot... every single day.

Edit: Yes, the 113 (+ Proving unit!) is better.

[BeBuLamar]

Nobody has answer for why brand new meters have blown fuse. I don't either except perhaps those are not brand new.

[coromonadalix]

There are two types of DMM users - these who have connected voltage to the current input and those who will.

That's called learning the hard way ...   and paying to put a new fuse

And now:  process your setup mentally before doing any measurements to avoid this mistake again ...

[coromonadalix]

Nobody has answer for why brand new meters have blown fuse. I don't either except perhaps those are not brand new.

 


I never saw this in many brand new meters i have bought : Mastech, Fluke, Beckman, Amprobe, bench or portable  ...  and all the old stuff i've bought  ...

The @OP  must be incredibly unlucky ... ?

[Fungus]

And now:  process your setup mentally before doing any measurements to avoid this mistake again ...

Moral: Never ever put your meter away with the leads in the amps connector. Always move the leads back to the volts socket when you've finished measuring amps.

(and get a meter with jack alert... I think all Brymens have it)