Author Topic: EEVblog #1007 - Is a $25 Multimeter Any Good  (Read 164708 times)

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Offline MacMeter

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #325 on: July 23, 2017, 06:07:20 pm »
Well, not sending ANENG dozens of orders would be a start ;). As would be not recommending any meter that so blatantly lies about its safety.

I bought one as I'd like to believe I kinda know what I'm doing. But in an effort to continue to beat this dead horse some more, I do take issue with ALL the FAKE labels, on many Chinese products, this includes UL listings etc. Besides the fact it's lying and deceptive, and can be very unsafe for many not knowing about this ongoing practice. And this of course extends well beyond DDM's. So far it seems there is little we can do to dissuade the Chinese from these deceptive practices, and the old "vote with your wallet", has had little effect so far, as many simply buy the cheapest products they can find, with little regard to how honesty the product may be marketed. Making others aware of these false labels is a good thing for those that may read online reviews and forum posts, regardless how many times the horse is beaten.
 

Offline joeqsmith

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #326 on: July 23, 2017, 06:34:33 pm »
The public don't know what the markings mean anyway, removing them would make very little difference.

Based on the number of comments I receive, a fairly high percentage of people buying meters don't know what they mean.  Strange with having the internet at your fingertips.   But not making the standards available to the public does not help. 

If it were important, there would be government funded watchdog groups that spot checked the companies who self certify.   Meters do not pose the same threat as food for example so there is no FDA equivalent.  Imagine if this group were able to impose fines if they failed to meet their claimed ratings or prevent import/exporting of the product.    Even if there were such a branch like the FDA, I can see like DOT standards for helmets, were we could have a private watchdog like Snell if the problem were really big enough. 

Just blabbing....

Imagine extending this to the world of handheld meters, Snell vs DOT:

http://www.smf.org/docs/articles/dot
« Last Edit: July 23, 2017, 06:42:07 pm by joeqsmith »
 

Offline MacMeter

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #327 on: July 23, 2017, 06:48:55 pm »
The public don't know what the markings mean anyway, removing them would make very little difference.

Based on the number of comments I receive, a fairly high percentage of people buying meters don't know what they mean.  Strange with having the internet at your fingertips.   But not making the standards available to the public does not help. 

If it were important, there would be government funded watchdog groups that spot checked the companies who self certify.   Meters do not pose the same threat as food for example so there is no FDA equivalent.  Imagine if this group were able to impose fines if they failed to meet their claimed ratings or prevent import/exporting of the product.    Even if there were such a branch like the FDA, I can see like DOT standards for helmets, were we could have a private watchdog like Snell if the problem were really big enough. 

Just blabbing....

Imagine extending this to the world of handheld meters, Snell vs DOT:

http://www.smf.org/docs/articles/dot

Agreed, but it seems the Chinese, and perhaps other countries don't seem to care much about adhering to any standards, international or not. They even clone their own clones of products.
 

Online alm

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #328 on: July 23, 2017, 07:09:45 pm »
Making people aware is always the best solution, not trying to ban/censor.
Making people aware is what half this thread is about :P. I would like to see equipment with fake safety markings banned, but I do not think anyone was talking about censoring the discussion.

Based on the number of comments I receive, a fairly high percentage of people buying meters don't know what they mean.  Strange with having the internet at your fingertips.   But not making the standards available to the public does not help. 
Having scanned through some of those standards, I am not convinced that publishing them freely would do anything to educate the public. Not that I am arguing against freely available standards, but it would do about as much for education as reading a copy of Heaviside's paper on Maxwell's equations for understanding of electricity. Basic information about test equipment safety is available for free in white papers from the likes of National Instruments and Fluke.

If it were important, there would be government funded watchdog groups that spot checked the companies who self certify.
Even in the EU, where there are such groups (collected in the interestingly named RAPEX), they can only cover a tiny fraction of all products, and seem to focus mostly on consumer products. If the consumer imports their own stuff through eBay/AliExpress, how is any national organization going to test it? Putting a Hi-Pot tester at the customs office? Order random stuff from AliExpress and test it?

I imagine eventually a bunch of people will die due to defective products, there will be outcry, and there will be some knee-jerk response from politicians like requiring a license to import anything electronic.

Offline Fungus

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #329 on: July 23, 2017, 07:17:10 pm »
Based on the number of comments I receive, a fairly high percentage of people buying meters don't know what they mean.  Strange with having the internet at your fingertips.   But not making the standards available to the public does not help. 

Not strange.

Even Fluke's basic "ABCs of multimeter safety" says things like:

Code: [Select]
CAT I
• Protected electronic equipment
• Equipment connected to (source) circuits in which measures
are taken to limit transient overvoltages to an appropriately
low level
• Any high-voltage, low-energy source derived from a high-
winding resistance transformer, such as the high-voltage
section of a copier

Is Joe Public expected to understand that?

What they need is clear advice like "Get CAT III 600V for mains work"

I don't see any reason to go for less when you can get that for $42.

(and I'm sure China could make that for $15 if they had an incentive - all they need to do is remove the current ranges and spend a few cents on making the meter die without drama if overloaded).

Even better, a big colored symbol which indicates "Safe for mains AC" and leave the CAT ratings for the engineers.

Yes, it divides the multimeter world into "mains rated" and "not" but I don't see that as a problem.
 

Online ebastler

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #330 on: July 23, 2017, 07:20:04 pm »
It seems that we have found a good solution to the unfortunate situation that two threads were discussing the same new AN8008 meter:
Please keep it up! This enables me to unsubscribe from this thread, and just monitor the other one .
 

Offline joeqsmith

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #331 on: July 23, 2017, 08:01:39 pm »
I agree, the standards are dry and there is a lot of room for interpreting them.  It seems even the designers do not agree.   But keeping them out of the public where they could be discussed in detail seems to counter the whole point of having them.   Personally I would expect the entire reports to be made public.   The public ends up paying for the testing in the end anyway.   

I view multimeters a little different than most products, thinking people that would buy this type of product would have some technical knowledge.  But right there you can see that my thinking is flawed!!!  :-DD   

I wonder what drove UNI-T to offer the GS version of the UT61E.   To Fungus's comment, if the body is not going to ensure the mark has any credibility, there was no reason for mandating it in the first place.   

Quote
.... how is any national organization going to test it? Putting a Hi-Pot tester at the customs office? Order random stuff from AliExpress and test it?

That's a very good question.  I think Snell started out doing just that.  Buying a small number of helmets, testing them then making the results public.  Eventually you started to see articles in popular magazines that helped educate the public.   Over time, people like me started using that public list to determine what to buy.   I would not use a helmet that was not Snell approved.  It's a fairly high risk hobby in the first place and proper gear is important.     

I can tell you from my own little benchmarking, unlike with Snell, it's driven out of general curiosity rather than a tragic death of a friend. Had it been the later, I may have been following the actual surge tests rather than what is more important to me, robustness or the meters ability to survive some minimal transients.    Believe me, I have zero thought of ever trying to turn it into a money making business or charging for the information I collect.  But, you may be amazed at the backlash I receive from running such tests!   :-DD 

Offline joeqsmith

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #332 on: July 23, 2017, 08:03:07 pm »
Based on the number of comments I receive, a fairly high percentage of people buying meters don't know what they mean.  Strange with having the internet at your fingertips.   But not making the standards available to the public does not help. 

Not strange.

Even Fluke's basic "ABCs of multimeter safety" says things like:

Code: [Select]
CAT I
• Protected electronic equipment
• Equipment connected to (source) circuits in which measures
are taken to limit transient overvoltages to an appropriately
low level
• Any high-voltage, low-energy source derived from a high-
winding resistance transformer, such as the high-voltage
section of a copier

Is Joe Public expected to understand that?

What they need is clear advice like "Get CAT III 600V for mains work"

I don't see any reason to go for less when you can get that for $42.

(and I'm sure China could make that for $15 if they had an incentive - all they need to do is remove the current ranges and spend a few cents on making the meter die without drama if overloaded).

Even better, a big colored symbol which indicates "Safe for mains AC" and leave the CAT ratings for the engineers.

Yes, it divides the multimeter world into "mains rated" and "not" but I don't see that as a problem.

I agree about the need to have some VERY CLEAR ADVICE!   You could publish a new book, "Making measurements safely" and it would sell, maybe...  Well, I would read it anyway.     

Your target audience should be the 10 year old who goes on a take your kid to work day, and gets to be on the factory floor and make some measurements, without supervision....   If you could put it in terms that the video game playing 10 year old understands, I believe you have a hit.
« Last Edit: July 23, 2017, 08:09:16 pm by joeqsmith »
 

Offline kalel

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #333 on: July 23, 2017, 08:15:27 pm »
Your target audience should be the 10 year old who goes on a take your kid to work day, and gets to be on the factory floor and make some measurements, without supervision....   If you could put it in terms that the video game playing 10 year old understands, I believe you have a hit.

A video game with multimeters, you say? Okay, you didn't say it, but... if such a thing would have a market and be sponsored by someone with a budget, e.g. Fluke, I'm sure someone would take the challenge. A hero electrician saving the day. The more safety procedures are observed, more points are received.

But on the serious side, I'm sure no one wants people learning about multimeters and safety from games.
 

Online alm

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #334 on: July 23, 2017, 08:16:30 pm »
What they need is clear advice like "Get CAT III 600V for mains work"
And then they go out and buy an AN-8008 :P.

Offline Specmaster

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #335 on: July 23, 2017, 08:18:25 pm »
Surely, at least for those here in the United Kingdom there is no need to use a multimeter on mains supplies which is where most people will come across high energy sources as this link clearly demonstrates.

http://martindale-electric.co.uk/martindale-vi-15000-voltage-indicator-p-1870.html

Using these devices in the link meets all the HSE requirements and also the Wiring Regulations as well as removed the chance of operator error, even if the circuit is live as there is no range switch, or current ranges etc that could be selected. Using these devices will ensure 100% safety for the operators of such equipment, no??? 
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Offline IanB

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #336 on: July 23, 2017, 08:35:28 pm »
Surely, at least for those here in the United Kingdom there is no need to use a multimeter on mains supplies which is where most people will come across high energy sources as this link clearly demonstrates.

http://martindale-electric.co.uk/martindale-vi-15000-voltage-indicator-p-1870.html

Using these devices in the link meets all the HSE requirements and also the Wiring Regulations as well as removed the chance of operator error, even if the circuit is live as there is no range switch, or current ranges etc that could be selected. Using these devices will ensure 100% safety for the operators of such equipment, no???

You can use such a voltage indicator to check that a circuit has been de-energized, but after that you may need to check continuity or resistance on circuits. That device doesn't say it can test continuity. So what happens if you are testing continuity or resistance with a multimeter and you accidentally test a live circuit?
 

Offline Specmaster

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #337 on: July 23, 2017, 11:06:48 pm »
Surely, at least for those here in the United Kingdom there is no need to use a multimeter on mains supplies which is where most people will come across high energy sources as this link clearly demonstrates.

http://martindale-electric.co.uk/martindale-vi-15000-voltage-indicator-p-1870.html

Using these devices in the link meets all the HSE requirements and also the Wiring Regulations as well as removed the chance of operator error, even if the circuit is live as there is no range switch, or current ranges etc that could be selected. Using these devices will ensure 100% safety for the operators of such equipment, no???

You can use such a voltage indicator to check that a circuit has been de-energized, but after that you may need to check continuity or resistance on circuits. That device doesn't say it can test continuity. So what happens if you are testing continuity or resistance with a multimeter and you accidentally test a live circuit?
Thats the whole point, you do not get out the multimeter until you have confirmed that the circuit is dead and isolated safely by padlocking it off. Risk from using multimeter on the wrong range should then be zero. This is indeed what electrical engineers who work on large circuits such as factories etc are trained to do. The problem arises when unqualified and unsupervised people start to dabble in areas that they should not be anywhere near. These, multi padlock devices are nothing new, they have been around for decades, I remember them when I did my apprenticeship and I'm retired now. The safety issues and the need for these CAT ratings have in my opinion been largely driven by the continual decline in trade disciplines by employers driving the cost down by employing in less well qualified staff and then make them into multi-discipline trades people so 1 person can do the work of 2 or more people, thereby increasing their profits. But that is another topic all together and here in the UK we have seen some staggering examples of how cost cutting can have devastating effects on the lives of others. Thats another can of worms that is currently best left untouched, this an engineering forum, not political.
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Offline kalel

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #338 on: July 23, 2017, 11:15:43 pm »
Well, at least for non-professionals on this forum, do we have a safety guide written somewhere (either as a post or a video)?
Perhaps some basics on safety when using a meter, aimed at novices rather than professionals.

Ah, it's probably all around the forum. :)



 

Offline IanB

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #339 on: July 24, 2017, 02:57:15 am »
Thats the whole point, you do not get out the multimeter until you have confirmed that the circuit is dead and isolated safely by padlocking it off. Risk from using multimeter on the wrong range should then be zero. This is indeed what electrical engineers who work on large circuits such as factories etc are trained to do.

Working in an industrial setting is one thing. But I wasn't thinking of that. I was thinking of working in non-industrial settings like residential buildings and office spaces, HVAC systems and such like. Does your home have multi-padlock safety interlocks? Can you be sure that all the wires in a junction box are on the same breaker? They should be, but there are certain cases in old buildings (and my house) where they aren't.
« Last Edit: July 24, 2017, 03:01:06 am by IanB »
 

Offline joeqsmith

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #340 on: July 24, 2017, 03:27:18 am »
Personally, I liked the 8002 for what it was.   It had lots of features including temperature, low cost and small.  I think I was able to read 200MHz with it.  Compare that with the Gossen and 121GW at 1MHz.  If I wanted to mod the meter for low voltage use (besides removing the CAT marking) I wonder if there is enough room in there to add some basic protection.   

Looks like the 10A fuse was open. The PTC seems fine. 

If anything, gives you some idea of what went on inside the meter.  Keep in mind this thing actually out survived the Dave's 121GW.  It would have done very well in that very first set of tests I ran with the sub $50 meters.       

Offline G7PSK

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #341 on: July 24, 2017, 08:14:04 am »
Thats the whole point, you do not get out the multimeter until you have confirmed that the circuit is dead and isolated safely by padlocking it off. Risk from using multimeter on the wrong range should then be zero. This is indeed what electrical engineers who work on large circuits such as factories etc are trained to do.

Working in an industrial setting is one thing. But I wasn't thinking of that. I was thinking of working in non-industrial settings like residential buildings and office spaces, HVAC systems and such like. Does your home have multi-padlock safety interlocks? Can you be sure that all the wires in a junction box are on the same breaker? They should be, but there are certain cases in old buildings (and my house) where they aren't.

I think that to a large extent the CAT ratings have been used as a marketing tool by some company's even driven by them.

There are lock out devices for domestic switch boards and offices HVAC etc and should be used especially where there are other people working on the system or where there are people who might turn the power back on when they find the coffee machine or whatever is not working. Lock out devices should be used by more than electricians, I know of a case where a farm worker was cleaning an elevator, he had done all the proper things like turn off the main power switch. Unfortunately for him someone else came into the barn saw the lights were out and went and turned the power back on, this started the elevator and he was pulled in and drawn halfway up before the idiot that turned the power on heard his screams realized what was going on and turned the power off again, when the fire brigade arrived to extricate the man they had to turn the power on and wind the man the rest of the way up the elevator in order to get him out by that time his hand was in a pretty poor state. So any one who is going to do any thing which involves shutting off power needs to be able to make sure the power is not coming back on until they are ready and it is safe.
 

Offline b_force

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #342 on: July 24, 2017, 08:48:16 am »
Thats the whole point, you do not get out the multimeter until you have confirmed that the circuit is dead and isolated safely by padlocking it off. Risk from using multimeter on the wrong range should then be zero. This is indeed what electrical engineers who work on large circuits such as factories etc are trained to do.

Working in an industrial setting is one thing. But I wasn't thinking of that. I was thinking of working in non-industrial settings like residential buildings and office spaces, HVAC systems and such like. Does your home have multi-padlock safety interlocks? Can you be sure that all the wires in a junction box are on the same breaker? They should be, but there are certain cases in old buildings (and my house) where they aren't.

I think that to a large extent the CAT ratings have been used as a marketing tool by some company's even driven by them.
I don't even think that, I am sure about it.

On top of that I have seen many people, who would never ever work on these high energy projects, but they still would rather buy a high CAT rating multimeter.
Just because it gives a sense of trust I guess. But technically speaking it's absolutely not important.
Most people don't even use their meter for mains power (115/230V)

Like I said before, I would never work on these type of projects with some extra safety features besides my multimeter.
One very good safety feature is simply sending people away or preventing them for even coming close to the things I am working on at the moment.
In most stories you read, the worst accidents happen when other people did something you didn't want in the first place.

Offline Fungus

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #343 on: July 24, 2017, 09:37:27 am »
On top of that I have seen many people, who would never ever work on these high energy projects, but they still would rather buy a high CAT rating multimeter.

We're now up to page 15 of that debate in this thread and there are many others.
 

Offline labeanchik

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« Last Edit: July 24, 2017, 09:50:32 am by labeanchik »
 

Offline madires

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #345 on: July 24, 2017, 10:17:28 am »
On top of that I have seen many people, who would never ever work on these high energy projects, but they still would rather buy a high CAT rating multimeter.
Just because it gives a sense of trust I guess. But technically speaking it's absolutely not important.
Most people don't even use their meter for mains power (115/230V)

IMHO, the problem is that the common EE or hobbyist would use his DMM on mains because that's the tool he got. So he's looking for proper CAT ratings, despite a DMM for electronics isn't the right tool for mains. The proper tools for mains are a Duspol or similar voltage indicator with a switchable low impedance mode for usual tasks, a rugged DMM for sparkies without current measurement, a clamp meter for current measurements (the 10 or 20A range of an electronics DMM is laughable) and isolation/wiring testers. The Duspol needs two hands for operation, a DMM three. Clips, hangers and magnets are nonsense if you're on a ladder working on a junction box above you. If you're working on high voltage or high current stuff you will need another set of tools again.

TL;DR: Using an electronics DMM on mains is as bad as a neon screwdriver.
 

Offline plazma

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #346 on: July 24, 2017, 10:26:44 am »
Revolutionary! The first 4 1/2 digit multimeter with only 4 digits in the display.
If the other specs are as credible, I'll pass on it...

EDIT: I see that they have photos of two slightly different meters in that product description. They seem to have added space for the extra "1" in a revised version.



Here is  this?

https://www.banggood.com/ru/ZEAST-282-20000counts-Multimeter-Digital-Professional-Voltmeter-Current-Tester-Auto-True-RMS-p-1175450.html?rmmds=detail-bottom-viewalsoview

https://www.banggood.com/ru/HY-19E-20000-Counts-NCV-Multimeter-AC-DC-Voltage-Current-Resistances-Capacitors-Diodes-Temp-Tester-p-1153062.html?rmmds=detail-bottom-viewalsoview

https://www.banggood.com/ru/ZEAST-HY-19A-6000Counts-Digital-Multimeter-LCD-Backlight-Auto-AC-DC-Voltmeter-Ammeter-Ohm-Resistance-p-1175452.html?rmmds=newArrivals
The last one looks like a DTM0660 chip multimeter. It would be interesting to check the internals and UART modifications.
 

Offline Specmaster

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #347 on: July 24, 2017, 11:08:36 am »
We're now up to page 15 of that debate in this thread and there are many others.
Yep, thats because safety is an issue to most people and has to be taken seriously but with a balanced view on how and where the meter is going to used and your own skill set has to be taken into the equation as well. As has been already been mentioned, some people would rather buy a meter with decent compliance to the Cats and regulations even though they are not using it in the dangerous environments, just as a added feeling of security etc. or feel good factor.
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Offline cjs

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #348 on: July 24, 2017, 01:42:19 pm »
Is Joe Public expected to understand that?
What they need is clear advice like "Get CAT III 600V for mains work"

I think that's terrible advice, even if meters all had valid and tested category ratings. It's way easy to hurt yourself with any meter, no matter how good, if you don't know what you're doing.

Instead tell people "don't touch mains until you've had some minimal proper training," and then you can explain whatever you need about categories along with other essentials like PPE, proper work habits, and so on. In that context, phony meter category markings seem to me pretty near a non-issue because learning about how to deal with that is such a small part of the overall education.

 
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Offline Fungus

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Re: EEVblog #1007 - Is a $25 Multimeter Any Good
« Reply #349 on: July 24, 2017, 02:20:58 pm »
Instead tell people "don't touch mains until you've had some minimal proper training," and then you can explain whatever you need about categories along with other essentials like PPE, proper work habits, and so on.

Here in the real world the rednecks have been busy stockpiling their DT830Bs for decades.
« Last Edit: July 24, 2017, 02:26:57 pm by Fungus »
 


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