Multimeter safety

Safety must always remain priority number one when doing measurements with multimeters. Working safely, while making electrical measurements, is not rocket science. It’s a simple combination of careful planning, safe practices and using the right tools in the right way. The more voltage and current is present in the circuit, more careful you have to be. Fluke Safety video gives some overview on the multimeter measurements safety around power circuits.

Stock Multimeter Explosion shows one worst case scenario what can happen when you make mistakes with multimeter and high power energy source. This video illustrates why fused leads should be used with multi-meters. If you plug the leads in the wrong spot or have the wrong settings this is what happens. This video illustrates why fused leads should be used with multi-meters when measuring power circuits.

Check also High Energy Multimeter Destruction video for more examples of exploding multimeters and damages inside multimeters.


  1. Fused multimeter probes « Tomi Engdahl’s ePanorama blog says:

    [...] lethal voltages and short circuit current. Multimeter have fuses inside them, but those fuses do not always provide enough protection. Stock Multimeter Explosion video illustrates what happens when the fuse inside multimeter is not [...]

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    • Tomi Engdahl says:

      I have earlier used method in-house development + developer.
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  7. says:

    Write more, thats all I have to say. Literally, it seems as though
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  8. Tomi Engdahl says:

    10 Multimeter Makers With Models Under $150

    The handheld DMM (digital multimeter) is a tool that every engineer and technician needs. You probably have at least one on your bench or toolbox, whether at work or at home. At home, you’re likely to use a DMM on a home electronics project or to diagnose problems on your car, electrical wiring, or perhaps a kitchen appliance.

    Handheld meters are available online, through electronics distributors, local electronics stores, electrical supply stores, hardware stores, flea markets, Radio Shack (the few that remain), and on eBay. Here is a sampling of the meters you might find for under $150.

  9. Tomi Engdahl says:

    Multimeter Safety and Input Protection

    Electricity is a silent killer. You can’t see, hear or smell it, but it will bite if given the chance. While those working in offices and labs are in generally safe environments largely shielded from hazardous electricity, engineers, electricians and linemen are often directly exposed. They are at greater risk from electrical hazards and should get the best made device they can.

    If you intend to measure mains circuits, safety should be paramount in choosing the right meter. Just because a multimeter touts a high category rating and looks tough from the outside, and can measure nominal mains current without issue, doesn’t mean it can protect you in the event of a voltage spike.

    CAT-II: single phase circuits, for equipment connected to socket outlets, such as appliances and power tools. For testing the socket itself, you would want a CATIII meter.

    CAT-III: up to three phase systems and including single phase circuitry of installations; that is, beyond the socket and cord. Includes distribution boards, three phase outlets and commercial lighting.

    CAT-IV: where spike levels can be high, such as at a building’s source power; includes measurements of supply meters, main panel boards and outdoor conductors.

    Fuses: offer a basic level of protection and are typically not quick enough to protect a multimeter from transient exposure without the addition of further protection. They protect from excessive current, with High Rupture Capacity (HRC) type fuses providing the surest protection.

    Advanced Protection

    Along with HRC fuses, CATII-rated multimeters and up should also have a number of other components built in to protect from voltage spikes. These include power resistors, positive temperature coefficient (PTC) resistors (known as thermistors), zener diodes, and metal oxide varistors (MOVs). Brand, as much as price, may dictate whether or not these essential electronic components have been incorporated.

    Probes: good test leads are often overlooked but are equally important, since they are the point of contact with live conductors. They should have finger guards and shrouded jack plugs, and should be certified to the same category as the meter, if not higher.

    Along with good mechanical properties, input protection is the most important factor in selecting a safe multimeter.

  10. Tomi Engdahl says:

    ET201 Oscilloscope-Multimeter comes with a lot of surprises

    The EONE ET201 is one of the most affordable tools to visualize waveforms. It is also a decent multimeter and a safety hazard. In this video I am showing all pros and cons I could find about the scopemeter.

    costs 55$, has an oscilloscope (sorta) but it isn’t auto ranging? what a strange multimeter
    And they say that Germans can’t be funny!…ever!

    I really wish the Chinese would stop lying on the ratings like that. Anyone who actually needs a CAT IV is never going to believe it, and anyone who would believe it is never going to be near a circuit that needs it. If they’d just make an honest CAT II meter, which isn’t hard, everyone would be happy.

    “The manufacturer can circumvent my biggest complaint”
    This is a very very good point!
    Manufacturers have no idea what we want.
    Most of us would be fine with a 250v or lesser meter using glass fuses as long as it doesnt make bullshit claims!
    When they do make the big claims though they are obligated to back them in the product.

  11. Tomi Engdahl says:

    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.

  12. Tomi Engdahl says:

    EEVblog #929 – Designing A Better Multimeter

    Dave looks at the current measurement front end of a typical multimeter and figures out how to redesign it for lower burden voltage.
    It’s not quite as easy as you might think, there are compromises and traps for young players.
    And something you probably didn’t know about HRC fuses.

    EEVblog #931 – Designing A Better Multimeter PART 2

    Dave takes a look at how to optimise the low burden voltage multimeter design from PART 2 to eliminate some parts.
    And explains the µCurrent shunt circuit design and how that applies to this new optimised design.
    It’s basically a practical tutorial in circuit design optimisation.
    Then another design variation is presented using MOSFET switching that eliminates ones of the HRC fuses and the amplifier, and still lowers the burden voltage yet again!

  13. Tomi Engdahl says:

    EEVblog #712 – Uni-T UT71E Multimeter (Why Uni-T Meters Suck)

    Dave shows why Uni-T multimeters generally suck in this teardown (and a little bit of a review) of the $180 UT71E 0.025% accuracy multimeter with power measurement capability.
    He also opens the UT71A, UT61E, and compares the input protection and rating with a Brymen BM257.

  14. Tomi Engdahl says:

    UNI-T UT81C scopemeter teardown/review

    Input jacks are soldered directly to the PCB at one point. They are split type, bent metal. Certainly not as great as solid jack construction with stress relief.

    Note that UT81C has not the best input protection (glass fuses, overvoltage protection could be improved).

    DMM board has five crappy adjustment pots, processing PCB has one adjustment cap.

    USB interface works, basic functionality (streaming data only). Live screen viewing though USB communication, can save data, show current and saved waveforms.
    80 MS/s is true spec. Can test high voltages on scope. Scopemeter is useful for a single channel low freq. measurements.
    Killer feature – you can measure current waveform directly with DMM probes only! On µA/mA/A ranges!

    Issues with input impedance and absolute measurements.
    Not enough shielding – mains hum shows up if you are not careful.
    Probe adapter can be better (try not to lose this small piece).

  15. Tomi Engdahl says:

    $3 multimeter test & teardown

    Today I test a cheap multimeter from Ebay for 3 USD including shipping (DT830B knock-off). Does this thing work? Is it safe to use? What’s inside? Let’s see in this video :).

  16. Tomi Engdahl says:

    Multimeters for electrical installations

    Basics of multimeters, what they do and how to use them. This is from an electrical point of view – for electronics the features required will be different.
    Includes the basics of voltage, current and resistance, how to measure those three things, manual and auto ranges, CAT ratings, a look inside two multimeters.

    Thanks John. It was an interesting and informative video. Especially with regard to the dangers associated with shorting out in the amps setting and the low impedance setting. However, am I alone in thinking of Ned Flanders when you kept repeating “nothing at all” ?

  17. Tomi Engdahl says:

    THE BEST Multimeter tutorial (HD)

    What to look for in a multimeter and how to use a multimeter to measure voltage, current, resistance and continuity.

  18. Tomi Engdahl says:

    New 2018 LIDL Powerfix multimeter unboxing, testing, teardown

    Can you really get a fully safety-certified multimeter for 13 Euros?

    I unbox the last LIDL Powerfix multimeter and put it through its paces.

    Result: Thumbs up!

  19. Tomi Engdahl says:

    2018 LIDL multimeter, part 2 – Questions and answers

    A followup to the LIDL multimeter video to answer some questions.

  20. Tomi Engdahl says:

    Teardown of an Extech 380460 Milliohm Meter

    In this video, I did a teardown of an Extech 380460 Milliohm meter. High resolution teardown pictures can be found here:

  21. Tomi Engdahl says:

    How to Use a Multimeter – Beginner’s Crash Course

    Learn how to use a multimeter so you can start diagnosing some of those electrical system gremlins yourself!

    In this quick multimeter tutorial I take you through all the functions you’d use for DC circuits using simple examples you can try yourself.

    How To Use a Multimeter (For Beginners)

    MAGS How To Videos – How To Use a Multimeter (For Beginners)

    In this video I will help teach you how use a multimeter to test volts (AC & DC), amps and ohms. I will also show you how to test for both resistance and continuity.

  22. Tomi Engdahl says:

    Multimeter Protection Circuitry GDT vs MOV

    Short video showing the difference in how a gas discharge tube will clamp compared with a MOV when a 5KV transient is supplied. This video does not suggest which technique is more robust. Nor does it prove or disprove if a meter that uses GDTs will survive a surge test or not.

  23. Tomi Engdahl says:

    2500V vs a UT61E, guess who wins? Bonus: 5000V vs a Brymen BM869

    How do you kill a multimeter? Well it depends on the multimeter!

  24. Tomi Engdahl says:

    Multimeter Test Lead Shootout

    In this video we look at various multimeter test leads. We test unbranded leads from Aneng, and Owon, branded leads from Uni-T, Mastech, Fluke, and Probemaster. We conduct a subjective continuity test, and an objective four-wire resistance test. Watch the video for the results.

    #288 Multimeter Test Lead Set Review

  25. Tomi Engdahl says:

    Can crappy probes hold back a good multimeter? The difference is surprising! – #0077

    After doing my $50 multimeter shootout, I started to see a pattern. Most multimeters have crappy continuity testers. (At least in the $50 range.) But the crappiness wasn’t consistent. Sometimes it seemed they responded quickly, and other times, it didn’t. This was a clue. It told me that the probes might not be giving a clean connection and causing the multimeter to appear to have a bad continuity tester. But could be crappy probes be at fault?

  26. Tomi Engdahl says:

    Probe Master 8017s and Belden 8899 Wire Tested to Failure

    A Probe Master 8017s and 46″ of Belden 0905 8899 002 test lead wire is tested to destruction. Two banana jacks are attached to the Belden wire for testing. Both are swept from 2 to 20 Amps and then from 5 to 60 Amps.

  27. Tomi Engdahl says:

    Multimeter Probes – Agilent, Fluke and Probe Master

    Mavromatic reviews a few Digital Multimeter (DMM) probes. The TL-910 from Fluke, the 34138 from Agilent (comes with Agilent 34461A Bench Multimeter) and the 8044SK from Probe Master that are Made in America.

  28. Tomi Engdahl says:

    eevBLAB #33 – Why Gold Plated Probes Matter

    Dave demonstrates why gold plated multimeter probes matter, and why you should be using them for all your electronics measurements.
    NOTE: Many people didn’t understand the point of this video. It’s about oxidisation of contacts, gold basically doesn’t do this, other probes can.
    Also gold probes are not necessarily recommended for regular high current, high power electrical use, that’s what I mean by an “electronics use”, as opposed to “electrical” use which is why Fluke for example don’t offer gold plated leads.

  29. Tomi Engdahl says:

    Electrical Measurement Categories – CAT I II III IV

    Measurement categories for electrical measurement equipment such as multimeters.

    CAT I equipment is not suitable for connection to the mains supply, CAT II and above is, but the distance from the energy source is important, with CAT IV being nearest to the energy source such as where power enters a building.


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