EEVblog #373 - Multimeter Input Protection Tutorial

Everything you ever wanted to know about how Multimeter input protection works.
Using the Fluke 27 as a baseline example.

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[svampebob]

I like how you've manage to keep the same content quality over +700 videos!
This was really informative without being too simplified or complicated!
I've been watching your videos since I started my studies. I've learned so much from watching your videos over 5 years, there's only so much you can learn at school and there's only so many cases you can get at work :)

[DanHaiduc]

15:55 is where the voltage, resistance, capacitance measurement part starts.

This is one of the best EEVblog episodes. A lot of this stuff in the previousones, but now I can understand everything finally! Thanks for that!

[Afrotechmods]

Great video one of my faves yet. I take it that one must also look at the I^2T rating of the fuse and make sure that it's guaranteed to pop first before the diode bridge goes up in flames?

[sysmatt]

Really good one Dave! ... And reading the automated transcript is hillarious poetry...
8:16isolation slots in the typically between input jacks between components
28:20southern white physically have a barrier between the vote is jack
28:24and ground all the at current jackson might physically have
29:56dammit sucked westphal at a certain and say will get his elbow teaching put
30:00jacket
30:01ceremony gently jack is going to get through a three point five kind while

[andersevenrud]

Thanks, Dave for making all of these videos on how stuff works. You always manage to explain these advanced circuits and functions in a way that a beginner like myself can understand.
Love your enthusiasm! Almost as if it's transmitted trough the screen, because every time I watch one of your videos my fingers start to itch for either creating something or tearing something apart!

[knoxpruett]

Excellent, as usual! Your video's are the best!
I am also an E.E. & E. hobbyist and still gain knowledge every time I watch one of your videos! I just can't acquire Science/Electronic knowledge fast enough, but you help a lot. There is so much fun stuff out there.
Thank you very much!

[akkudakkupl]

5:06
Been there, done that.
Was measuring a 3F engine current (with a primitive switch per phase arrangement) and shunted 400V mains with the meter by mistake (NEVER TRY TO DO YOUR WORK TOO FAST!). Awful bang, lots of fear and a dead meter. Thankfully it didn't catch fire. And thankfully I didn't catch any amps.

[UberAlphaSirus]

Dave, your white board stuff clears up so many doubts I have on things I'm not used to. Thanks for sorting MOVs out for me.

[PrimalEdge]

you're videos are addicting Dave, I work from home and just have your stuff running all day, love the new stuff, and the old videos are great to re-review.

[grumss]

Thankyou Dave, watched half of this Vid and had a fluke 789 diagnosed in minutes! (input MOV X2 faulty)..

[armenatorvan]

Thanks for this. I knew my meter was only good for CAT I (not the claimed CAT IV) but now I can see that despite the fuses, rectifier and PTCs, there's no MOVs or isolation, and fairly wimpy PCB tracks. Good to know exactly what's wrong.

[trooper]

This is one of the best channels on YouTube.
Dave you are awesome!

[EEVblog]

Well, there is the recommended fuse of course. If you don't buy the "approved" one, then you are of course on your own and should consider stuff like that. But all quality brand HRC fuses should have a very similar rating in that respect.

[krisztianszirtes]

Once I threw a 10A unfused range right across the mains... I kicked off two 16A breakers in series. Fun stuff.

[GalcoIndustrial]

I'll be sure to check them all out.

[clems]

A fellow engineer had borrowed my DMM to calibrate an transducer of 4-20ma. He left the leads plugged into the milliamp jacks, I used this same meter later without checking the lead configuration,  across the mains of a 575VAC buss. ...Yeah  B O O M !!!  The meter exploded in my hands. This was a Greenlee meter, not the highest quality but a decent meter.

[GalcoIndustrial]

Hi Dave, just wanted to say this video looks great and very informative. Just subscribed and look forward to seeing more of your videos.

[viesturssilins]

Thank you, Dave! I was very keen to learn more about this exact subject! You are the best!

[RNdin]

CTIMEPRODUCTIONS
It will certainly help out the overall safety of the meter as a whole, but if the meter originally came with a glass fuse in it, chances are it's a lower quality meter anyways. If the fuse goes on a cheap meter because you connected it across the mains, chances are the meter is going to be toast. Using an HRC fuse instead of a glass fuse won't prevent that, but it will prevent that fuse from throwing arc plasma and/or shrapnel around the inside of the meter case. That could mean the difference between a startled but unharmed meter user, and a crispy critter!