For those that swear by their HF Freebie Multimeters

[pedrodagr8]

So a gentleman over at EEVBlog has been putting a bunch of budget multimeters through a test. His most recent tests have involved a brief high voltage, low energy pulse followed by a single cycle of 120V AC line. The idea is to simulate what a multimeter might encounter in a normal situation. Most voltage spikes are VERY low energy but the AC line can still supply a lot of energy. The results have been VERY interesting.

Here is his testing of the HF multimeter. Not quite a spectacular explosion but you still don't want this in your hand. The interesting part starts at around 1:30

Keep in mind, this is much more real-world scenario type of testing compared to some of the other scare videos you see.

 

[404]

Yes it has serious problems. It was free. I use it but don't trust it. For BS stuff I guess it is kind of okay sort of I guess. If I have to. I use my Fluke when I can find it.

 

[George in Rancho Cordova]

In the first test, it appears that the circuit board did its job protecting the fuse from damage.

 

[goodysgotacuda]

It's free, I consider it better than nothing and only really use it if a better one isn't available. Diagnosed by father-in-law's horn problem just a week ago and that's all he had available. Worked for me.

 

[Empty Pockets]

Even though it was free.... Prolly overpriced. I have a Fluke, works good for me.

I wonder if HF would charge a restocking fee?

 

[Bluedodge]

Dumb question, but who puts 750 volts through a volt meter?

120v? Yeah.
240v? Yeah.
440v? Occasionally.

But 750?

 

[steed andersen]

Reminds me of Edison promoting DC over Tesla's AC. Highly slanted.

 

[TNToy]

In the first test, it appears that the circuit board did its job protecting the fuse from damage.

*Laughs in a darkly amused way*

 

[sometoyotaguy]

I've never found one that would work correctly for reading resistance. They might work ok with a decent set of leads.

 

[CNGsaves]

That was a torture test . . . more like . . . . DESTRUCTION . . . "test" . . .
. . . . and . . . Yeah, 750v will do some damage.

I sure didn't see anywhere in that video where . . .
. . .. the YouTube tester subjected his Fluke to 750v to see if it would blow up ??

Question for normal Joe is whether in NORMAL situation, would the cheapie HF multimeter give an accurate enough reading to be helpful. For free, it can't hurt to throw in your mobile electrical repair box.

 

[shoggoth80]

I used mine for the 9v battery...

 

[JDon99]

Dumb question, but who puts 750 volts through a volt meter?

120v? Yeah.
240v? Yeah.
440v? Occasionally.

But 750?

The PWM output of a VFD can get up there in voltage...

 

[DenisG]

Looks like the test was contrived to get the result that he wanted.

 

[finn]

Someone has an agenda.

 

[pedrodagr8]

It is funny, the amount of denial and confusion in this thread (some of it is his fault). He did NOT run this at 750V, he put the meter in the 750 RANGE, as I explained in the beginning. He selected this range because that is the range required to check household voltages. These tests were specifically designed to test something in more real world conditions. They test a very low energy, high voltage spike (such as encountered by an inductive kick back into the high impedance of a meter, etc.) followed by a single cycle of 120V AC (I think with 2 ohm impedance). These are conditions that people, not just tool hobbyists or electronics hobbyists, could encounter in their every day use. Not common that it happens all of the time but certainly common enough to be the most common mode of failure. This is type of scenario the standards organizations worry about when they rate meter safety.

Dumb question, but who puts 750 volts through a volt meter?

120v? Yeah.
240v? Yeah.
440v? Occasionally.

But 750?

He didn't put 750V through it, he set it to the 750V range, he could have explained it better.

That was a torture test . . . more like . . . . DESTRUCTION . . . "test" . . .
. . . . and . . . Yeah, 750v will do some damage.

I sure didn't see anywhere in that video where . . .
. . .. the YouTube tester subjected his Fluke to 750v to see if it would blow up ??

Question for normal Joe is whether in NORMAL situation, would the cheapie HF multimeter give an accurate enough reading to be helpful. For free, it can't hurt to throw in your mobile electrical repair box.

He didn't test at 750V, the range was 750V. Check his other videos, he actually tests multiple Flukes. The Fluke 101 he tested survived up to 12kV , 2ohm source impedance, 50uS FWHM. Interestingly, his worst performing Fluke was the 87V which its suspected to be a one off failure because the rest of the Flukes performed WAY WAY better.

Looks like the test was contrived to get the result that he wanted.

Someone has an agenda.

Not at all, if you want to know the background. He designed this tester to work through a variety of ranges and voltages to test the meters robustness. He tested dozens of meters this way, not just the HF one. None of the other meters failed like this. ALL of the rest at least kept the explosion within the case of the meter. The tests are SIGNIFICANTLY less stringent than those required by Underwriters Labs. This scenario is certainly within the realm of possibility for most meters to encounter and this meter failed HORRIBLY. If he was trying to contrive a result, he would have tested this meter and this meter only. As I mentioned above, he tested a Fluke 101 (a $50 meter from China) all the way up to 12kV, 2 ohm source impedance, 50us FWHM before it failed. This performance is just about the worst out of ANY of the meters he tested PERIOD.

EDIT:
Here is the list of meters he has tested so far (taken from his results spreadsheet):

Amprobe: AM-510, AM-530
BK Precision: 2703C, 2705B
Brymen: BM869S
Cen-Tech: 98025, P37772, P98674
CircuitTest: DMR-6550
Extech: EX430, MN16A
Fluke: 17B+, 101, 107, 87V (will soon be testing the Fluke 115)
Gardner Bender: GDT-311
HoldPeak: HP-760H
Innova: 3320
Klein: MM500, MM2000
Mastech: MS8264, MS8229
RadioSahack: 2200087
Sears: DM-301
SouthWire: 12070T
TekPower: TP40, TP2844R
Uni-T: UT61D, UT61E, UT90A, UT139C
UTL: UTLDM 2

 

[gungatim]

Dumb question, but who puts 750 volts through a volt meter?

120v? Yeah.
240v? Yeah.
440v? Occasionally.

But 750?

uh yeah, I only use it for 12v car stuff, or the resistance setting...I don't think I've ever had any reason to use a meter on 120v...even testing circuits on electronics are either off or 80v or less dc....who even has 440, or 750 at home???

 

[rlitman]

In the first test, it appears that the circuit board did its job protecting the fuse from damage.

LOL. Look, what's to be expected from a Category II meter? It's fine for all sorts of low voltage testing. Not fine for testing mains voltage. If you want to do that, get a Category III meter (or IV if you're in my line of work).

 

[pedrodagr8]

LOL. Look, what's to be expected from a Category II meter? It's fine for all sorts of low voltage testing. Not fine for testing mains voltage. If you want to do that, get a Category III meter (or IV if you're in my line of work).

You mean CAT I?

From National Instruments:

Measurement Category I:
This category is for measurements of voltages from specially protected secondary circuits. Such voltage measurements include signal levels, special equipment, limited-energy parts of equipment, circuits powered by regulated low-voltage sources, and electronics.

Measurement Category II:
This category refers to local-level electrical distribution, such as that provided by a standard wall outlet or plug in loads (for example, 115 AC voltage for U.S. or 200 AC voltage for Europe). Examples of Measurement Category II are measurements performed on household appliances, portable tools, and similar modules.

Measurement Category III:
This category refers to measurements on hard-wired equipment in fixed installations, distribution boards, and circuit breakers. Other examples are wiring, including cables, bus bars, junction boxes, switches, socket outlets in the fixed installation, and stationary motors with permanent connections to fixed installations.

Measurement Category IV:
This category refers to origin of installation or utility level measurements on primary over-current protection devices and on ripple control units.

In my opinion if you need CAT II level protection, you really actually need CAT III because the line between the two is a very grey area. Especially for most non-electricians.

 

[rlitman]

You mean CAT I?

In my opinion if you need CAT II level protection, you really actually need CAT III because the line between the two is a very grey area. Especially for most non-electricians.

I mean Cat II. I see four "identical" 7-function-multimeters from HF.
Item#92020, 90899, 98025 and 69096
All four show Category II on their face (though I am skeptical of them actually meeting this).

The differences between the categories are actually better distinguished than the wording would suggest, and the youtube testing kind of measures this out (though he is aimed at testing "robustness" by testing to destruction, and not directly measuring a safety margin).

But first, we must understand that there is no such thing as simply a "Category II" meter. The measurement category rating must be accompanied by a voltage rating. The aforementioned HF meters are rated (liberally IMNSHO) at 1000V Category II.

At 1000V, a Category I meter must be able to withstand a voltage impulse (spike) of up to 4000V. The number increases to 6000V for Category II, 8000V for Category III, and 12000V for Category IV. THAT, and the requirement for safety clearances (spacing) are what differentiate the measurement categories.
You can see a voltage chart here:
http://www.ni.com/white-paper/5019/en/
note: that chart should clarify why some meters carry a double rating, such as Cat III 1000V / Cat IV 600V (like the meter next to me on my desk).

The idea behind this, is that a meter must not only withstand the voltage it is rated for, but also must have a safety margin in the event that it is exposed to a transient voltage spike. Such spikes are limited in their energy by the impedance of the circuit they are on. So for example, while you might encounter a rather high voltage while measuring test points on a microwave oven circuit board, you would not encounter a spike such as what is seen in the video that could blow up a meter in your face. So in such a situation, a Category I meter might suffice. Measurements made on residential branch circuits might only require a Category II device.
The impedance at your circuit panel is much lower, where Category III is needed (a Category III device may also be required on commercial branch circuits close to the panel).

So, if the ratings provided by HF are to be believed, their meter should be safe for any measurements you could make in your house, except at your panel itself. In my house, since I have a whole house surge suppressor, it might even be safe in the panel.

Fluke has a good discussion of this here:
http://faculty.riohondo.edu/jfrala/...ultimeter_safety_and_you_application_note.pdf

 

[pedrodagr8]

I am very familiar with all of that and everything you said is 100% valid. When I made the comment: In my opinion if you need CAT II level protection, you really actually need CAT III because the line between the two is a very grey area.

This was referring to the common user. I know how Cat III 1kV is essentially the same as Cat IV 600V. Most end users do not.

Otherwise, very good post though.

As for trusting HF CAT rating, I wouldn't. No more than the CAT rating from Uni-T, Mastech, etc.

As for me asking if you meant CAT I. The situation you described is more a CAT I description. Which is why I asked if you meant CAT I. Because the term mains doesn't appear until CAT II. That is all.

 

[rsanter]

The multimeter is one of the last things I will get for free from them.
I would much rather have the tape measure or the flashlight.
Neither one of those have ever blown up in my hand....and if I loose one I don't really care

Bob

 

[CSRPenFab]

I had one of the freebies and tried to test a 110v circuit with it.. Bad idea, the POS flashed in my hand, smoked a bit, then was dead. I'll stick to the free tape measures. I did buy a higher end HF multimeter and it's been fine for basic work such as motorcycle rebuilding.

 

[NUTTSGT]

The multimeter is one of the last things I will get for free from them.
I would much rather have the tape measure or the flashlight.
Neither one of those have ever blown up in my hand....and if I loose one I don't really care

Bob

I wouldn't even take the time to cut the coupon out of the ad.

I did see one at the swap meet a week and a half ago for either 5 or 7 dollars.

 

[zakmartin]

I've been a subscriber to the EEVblog channel for a long time now and have watched each of his videos (even the ones where he runs through mud). The guy hates Chicom products. I keep expecting him to do an Aussie-Gump version of "...and that's all I have to say about that." every time he reviews something that was made in China.

Edit:
At last count, I have 11 HF multimeters and none of them have come out of the packaging yet. My Fluke works like a top. I only collect the HF stuff because it's free for the taking with a coupon.

 

[Skin]

The guy hates Chicom products.

Cant agree. He's done a number of budget DMM reviews and hasn't really bashed quality Asian meters just because they're Asian. Off the top of my head he hasn't said much bad about low tier fluke (Chinese made) or decent Korean/Taiwan meters like TPI. In fact its mostly praise with the caveat that 'hey this isn't equal to a $200 DMM but its also a quarter of the price'.

What he bashes are Chinese knock-offs or things made with lowest bidder components and China just happens to dominate the market in garbage electronics since so much is produced there already.

 

[chris142]

I have had good luck with mine. I only do 12v or maybe up to 230v.They have an internal adjustment so I adjust them to read the same as my Fluke. I carry one in each car for parking lot repairs.

But what does that blue circle on the left side do?

 

[pedrodagr8]

I have had good luck with mine. I only do 12v or maybe up to 230v.They have an internal adjustment so I adjust them to read the same as my Fluke. I carry one in each car for parking lot repairs.

But what does that blue circle on the left side do?

That blue circle is to test the gain of transistors. It's a sign of a cheap meter. Whatever voltage is on the leads also shows up in that circle so be careful.

 

[ChevyEFI]

I have one that failed.
One that's fine.

I need to buy new leads for my sunpro because I like it better. Longer leads and the read-out seems like it's working more normally; less jumpy.

 

[chris142]

The hf ones do need a good battery.if the battery voltage goes down so does the accuracy

 

[B_Bimmer]

I still walk through harbor freight once a year or so just to see if anything catches my eye, and because my wife will be in the clothing store next door for the next thirty minutes anyway. I've had several of all the free coupon items. The tapes are surprisingly decent, a thousand of the flashlights aren't worth one 2 AA led maglight (the combo of crappy switches, crappy batteries, and crappy workmanship is simply mindnumbing), and the meters are... better than nothing, if you happen to get one that works, otherwise at least you got a free piece of wire that could help fix your issue. I thank God that I live in America and can have higher standards than that. The packaging on the last meter I bought felt more robust than the plastic housing on the harbor freight meters I've had.

 

[Mechanical Noise]

uh yeah, I only use it for 12v car stuff, or the resistance setting...I don't think I've ever had any reason to use a meter on 120v...even testing circuits on electronics are either off or 80v or less dc....who even has 440, or 750 at home???

Alot of electronics hobbyists play with vacuum tube equipment. B+ voltages are commonly 250 to 300 volts. Twice that across the secondary hot leads of a center tapped power transformer.

 

[Mechanical Noise]

Question for normal Joe is whether in NORMAL situation, would the cheapie HF multimeter give an accurate enough reading to be helpful. For free, it can't hurt to throw in your mobile electrical repair box.

I've got a couple of precision 10V references. They're supposed to be within something like +/- 0.05% or something like that. My HF meters are all within 1% of that.

 

[diggerrick]

People complaining about freebies? WTF?

THEN DON'T TAKE ONE!

 

[pedrodagr8]

I have one that failed.
One that's fine.

I need to buy new leads for my sunpro because I like it better. Longer leads and the read-out seems like it's working more normally; less jumpy.

Pamona 5519A leads are VERY nice at around $15-17. They are the same thing as the Fluke TL-71, just cheaper. One meter length, very flexible silicone cable, sharp tips, etc

The hf ones do need a good battery.if the battery voltage goes down so does the accuracy

One of the only good things is that when the meter drifts due to battery voltage, it drifts high. Drifting low would be much much worse.

Alot of electronics hobbyists play with vacuum tube equipment. B+ voltages are commonly 250 to 300 volts. Twice that across the secondary hot leads of a center tapped power transformer.

Times 1.414 for the peak-to-peak values.

I've got a couple of precision 10V references. They're supposed to be within something like +/- 0.05% or something like that. My HF meters are all within 1% of that.

It's not hard to make a multimeter that is 1% accurate in the DC and resistance range. That technology has been around since the late 70s as a single IC you could purchase. AC voltage and current is a bit harder and more expensive.

People complaining about freebies? WTF?

THEN DON'T TAKE ONE!

Because they are INHERENTLY UNSAFE. It's like getting a free ratchet that every time you use it, it might blow up in your hand taking out a finger or two. Yeah it's free, yeah if you use it carefully enough you might be ok, but at the end of the day the word still needs to get out. The fact is this meter isn't capable of what it is rated for.

 

[Mechanical Noise]

Because they are INHERENTLY UNSAFE. It's like getting a free ratchet that every time you use it, it might blow up in your hand taking out a finger or two. Yeah it's free, yeah if you use it carefully enough you might be ok, but at the end of the day the word still needs to get out. The fact is this meter isn't capable of what it is rated for.

They are inherently less safe but how much less safe? The HF meters are filling the same niche that's been around for at least 50 years. Used to be the 1 kohm/volt analog meters with the switch and resistors on a cheap circuit board.

I doubt any of the old bottom end meters were any safer than the HF meters. And there must have been millions of them sold.

So, what's the real world track record? If I'm going to claim some car is inherently unsafe, I won't have much trouble finding the deaths/million miles and comparing to other choices which are presumably more safe.

 

[rice rocket]

It is funny, the amount of denial and confusion in this thread (some of it is his fault). He did NOT run this at 750V, he put the meter in the 750 RANGE, as I explained in the beginning. He selected this range because that is the range required to check household voltages. These tests were specifically designed to test something in more real world conditions. They test a very low energy, high voltage spike (such as encountered by an inductive kick back into the high impedance of a meter, etc.) followed by a single cycle of 120V AC (I think with 2 ohm impedance). These are conditions that people, not just tool hobbyists or electronics hobbyists, could encounter in their every day use. Not common that it happens all of the time but certainly common enough to be the most common mode of failure. This is type of scenario the standards organizations worry about when they rate meter safety.

What?

He says he put 4000 volts into it.

 

[uart]

That meter was subject to much more than 750 volts in that video.

Sorry I don't see the point of that test when the author didn't disclose the exact nature of the test voltage waveform. (Edit. ok he eventually said in the comment section he used at least 4000 volts, as rice rocket pointed out above).

Ok I get it, if you apply a destructive voltage that is way higher than the meter's rating, then the $5 (or free) meter might fail somewhat more spectacularly than a several hundred dollar meter. Hardly surprising. I really can't imagine anyone working on anything close to serious power level stuff using that meter anyway.

That video is like showing someone with a 1/4" ratchet and a 12 foot cheater bar trying to remove a rusted axle nut on a large truck. Because yeah, that's how everyone on this forum with a 1/4" ratchet is likely to be using it. Hey, let's call it a "real world scenario" test for a 1/4" ratchet.

 

[MrGiggles]

I have a couple of them in my vehicles. I haven't had any trouble using them for automotive use, reading resistance, DC voltage, and current draw. That being said, they are worth what you pay for them, but still better than a test light. The leads are junk and break after a few uses.

 

[txvwnut]

My supervisor decided I needed to go to an electrical class, this was a four day course that gave you enough information to either trouble shoot a problem or get you electrocuted. This all depends upon how much knowledge you currently have before going into the class.

My lab partner for the class had a HF meter. After watching it volt swing way more than I new the bread board gen was swinging I asked him to kindly stomp on it and toss it in the trash. I then asked the instructor if he a had a Simpson or a Fluke we could borrow since I had left mine at work as no one was told to bring any tools with them.

Not only was it terrible at testing voltage it couldn't even do resistance worth a damn either.

 

[Mechanical Noise]

My supervisor decided I needed to go to an electrical class, this was a four day course that gave you enough information to either trouble shoot a problem or get you electrocuted. This all depends upon how much knowledge you currently have before going into the class.

My lab partner for the class had a HF meter. After watching it volt swing way more than I new the bread board gen was swinging I asked him to kindly stomp on it and toss it in the trash. I then asked the instructor if he a had a Simpson or a Fluke we could borrow since I had left mine at work as no one was told to bring any tools with them.

Not only was it terrible at testing voltage it couldn't even do resistance worth a damn either.

First thing you could have developed your electrical troubleshooting skills was that HF meter. New test leads might have scored you a gold star for that day. Extra credit for figuring out which lead was flaky.