Hobbie multimeter

[Fungus]

Taking a measurement at a socket before turning off the breaker and make sure it shows 240 VAC. Then turn the breaker off and make sure there is no voltage present. If the meter breaks between those two measurements - tough luck.

Why would you be "working" on a socket that shows 240V AC?

[Traceless]

Why would you be "working" on a socket that shows 240V AC?

I wouldn't that is why I use a meter to make sure there is no voltage present?

You don't wear gloves?

What is your point? Forget about turning of the breaker and make sure you switched off the right one, because everything will be fine if you wear gloves?

[madires]

Taking a measurement at a socket before turning off the breaker and make sure it shows 240 VAC. Then turn the breaker off and make sure there is no voltage present. If the meter breaks between those two measurements - tough luck.

Why would you be "working" on a socket that shows 240V AC?

What Traceless has explained above is a basic safety precaution tought to sparkies and other related professions over here. The idea is to check if your T&M gear works, i.e. that it can detect/measure mains voltage and also the lack of. This is part of the "5 safety rules".

BTW, for mains related work I'd recommend to use specialized T&M gear like a Duspol. Typical DMMs aren't suited well for that.

[Aldo22]

Somehow I can't quite follow.
Is it really safer to poke around in a lamp socket with the multimeter test leads than to simply hold the bulb by the glass and screw it in (perhaps with gloves, for the very careful)?
I can't imagine that. Are there any statistics on this?   

As I said, NCV helps.

[Xena E]

For proving a high energy electrical circuit a general purpose multimeter is not really the preferred equipment, and being safe doesn't need to be expensive in equipment cost, just as a basic example, A Fluke T90 can be had for as little as 50 quid new.

In the industrial setting I would say that technicians not proving disconnections and not putting shorting links on remote high energy circuits are the biggest source of accidents, perhaps only behind circuit identification mistakes, and multiple source "gotchas".

PV and their inverters are good traps for the unwary...

As for using cheap multimeters, I'm not knocking them, they're great value things, and safe when used within their ratings and with common sense.

My routine for working on any part of a fixed electrical installation is:
Prove the testing device.
Identify the circuit.
Switch off the breaker, and lock it off, plus tag the circuit as isolated.
Prove the circuit is dead.
Prove the testing device.

If you do not have control over the operation of the breaker then fit a suitable shorting link on the circuit.

X

[tooki]

Somehow I can't quite follow.
Is it really safer to poke around in a lamp socket with the multimeter test leads than to simply hold the bulb by the glass and screw it in (perhaps with gloves, for the very careful)?

Yeah that part of the discussion went off into the weeds… 😂

In the end, everyone is agreeing that you want to first prove your mains detection test device (whether a light bulb or a meter) works by proving it on a live circuit before using it to test the circuit to be turned off for work. They just don’t realize they agree on this because they’re arguing in circles around misunderstandings.

[bdunham7]

Somehow I can't quite follow.
Is it really safer to poke around in a lamp socket with the multimeter test leads than to simply hold the bulb by the glass and screw it in (perhaps with gloves, for the very careful)?
I can't imagine that. Are there any statistics on this?   

As I said, NCV helps.

That brings up an important point--test leads, specifically the tips.  Proper CAT III/IV test leads (yes, test leads and probes have CAT ratings and requirements) will have a minimal amount of exposed tip to reduce the chances of you shorting out something big.  You can start an arc-flash (high energy installations) or splatter molten metal blobs into your eyes (at home) more easily with bad probing than with even the cheapest of multimeters. 

I'm not a fan of NCV in a multimeter, I prefer the separate tool.  Single-lead voltage detection is better, but I find the most reliable NCV to be tools like Klein NCVT-1 or Fluke 1AC.

[madires]

Somehow I can't quite follow.
Is it really safer to poke around in a lamp socket with the multimeter test leads than to simply hold the bulb by the glass and screw it in (perhaps with gloves, for the very careful)?

IIRC, the context was about checking if a circuit is disconnected. Let's assume you're working on a lamp socket. A bulb would only indicate if (sufficient) current is flowing or not. It doesn't tell you if neutral or live is switched, if there's some coupled voltage from another wire, or if neutral and live might be swapped.

As I said, NCV helps.

What will an NCV tester tell me when there's coupled voltage from another wire?

[Aldo22]

Somehow I can't quite follow.
Is it really safer to poke around in a lamp socket with the multimeter test leads than to simply hold the bulb by the glass and screw it in (perhaps with gloves, for the very careful)?

IIRC, the context was about checking if a circuit is disconnected. Let's assume you're working on a lamp socket. A bulb would only indicate if (sufficient) current is flowing or not. It doesn't tell you if neutral or live is switched, if there's some coupled voltage from another wire, or if neutral and live might be swapped.

As I said, NCV helps.

What will an NCV tester tell me when there's coupled voltage from another wire?

I have no idea what you're talking about.

I thought it was about a broken light bulb, where you want to see if there is current on the socket before replacing it.
Whatever the purpose....
Personally, I would just screw in a new one, regardless of the switch being on or off, like probably 99.9% of people who don't get confused by electronics forums. 

[tooki]

Somehow I can't quite follow.
Is it really safer to poke around in a lamp socket with the multimeter test leads than to simply hold the bulb by the glass and screw it in (perhaps with gloves, for the very careful)?

IIRC, the context was about checking if a circuit is disconnected. Let's assume you're working on a lamp socket. A bulb would only indicate if (sufficient) current is flowing or not. It doesn't tell you if neutral or live is switched, if there's some coupled voltage from another wire, or if neutral and live might be swapped.

As I said, NCV helps.

What will an NCV tester tell me when there's coupled voltage from another wire?

I have no idea what you're talking about.

I thought it was about a broken light bulb, where you want to see if there is current on the socket before replacing it.
Whatever the purpose....
Personally, I would just screw in a new one, regardless of the switch being on or off, like probably 99.9% of people who don't get confused by electronics forums. 

Nnnnnno friend, it wasn’t about replacing a blown light bulb.

[madires]

I have no idea what you're talking about.

I thought it was about a broken light bulb, where you want to see if there is current on the socket before replacing it.
Whatever the purpose....

If you want to check that for whatever reason it would be the same procedure. Maybe I should add that what someone is doing at home at his own risk might not be what a sparky would do when following safety rules (for safety, liability, insurance and compliance reasons).

Personally, I would just screw in a new one, regardless of the switch being on or off, like probably 99.9% of people who don't get confused by electronics forums. 

I fully agree, that's what most would do.

[joeqsmith]

I don't want them for their safety.  I want them because they are electrically and mechanically more robust.
...
In other words, I want a meter that may actually survive if I do something stupid.   

Beyond that it is more a case of what is going to kill your meter rather than what might kill you. 

I understand, but these are considerations that primarily concern professionals or "hardcore hobbyists" who use the devices in hard, daily use.
I have about seven inexpensive meters, some of which have been around for decades and all of them still work. At most, a mA fuse blows once in a while.

For example, if you buy a ZT-225 or an AN870 for $27, the DMM probably costs less than the fuse on a “decent” meter.

Why should I care as a hobbyist who doesn't venture into dangerous areas?
It makes no sense to me economically or in terms of event probability.

I suspect there are many more people who share your opinion.   There is a reason so many low cost, unprotected meters are sold.   As mentioned, just look at the free meters that harbor freight gives away.   

But as you suggest, we are not all the same.  You feel sitting behind a 30V @ 10A power supply is safe where I consider that this 300W could easily mess you up.    You have

about seven inexpensive meters, some of which have been around for decades and all of them still work.

   I have my first Fluke which is also decades old which I damaged so may times because it has no input protection that I finally retired it.  Cost too much to repair.   Call me advanced, stupid, what ever else you like but  there is a reason I want robust tools.   You don't have such a need so save your cash.  No big deal.

[Fungus]

Why would you be "working" on a socket that shows 240V AC?

I wouldn't that is why I use a meter to make sure there is no voltage present?

How do you know if that socket is working or not?

[Aldo22]

there is a reason I want robust tools.

Sure, but there's also something between Fluke and "harbor freight".
With the ZT-225, for example, you can change the ranges without any problems, even if 230V is applied to Vin (something I would never do...).

https://youtu.be/UIml3TYDomE?t=314

There are also tests with the AN870, which apply 4kV to Vin and nothing happens, the meter works normally afterwards.
But as I said, this is not what I would use it for.

[joeqsmith]

there is a reason I want robust tools.

Sure, but there's also something between Fluke and "harbor freight".
With the ZT-225, for example, you can change the ranges without any problems, even if 230V is applied to Vin (something I would never do...).

https://youtu.be/UIml3TYDomE?t=314

There are also tests with the AN870, which apply 4kV to Vin and nothing happens, the meter works normally afterwards.
But as I said, this is not what I would use it for.

Sure, there is a very wide variance of products available and I've looked at a few of them, including ANENG.   Suggesting a meter can handle 4kV without any proof or further details is useless, wouldn't you agree?   There is a reason I will state I test a meter at 4kV peak, 100us FWHH, 2 ohm source.  I may even show the waveform.  I want to be very clear about what I am subjecting them to.   There is a big difference between that and say 4kV AC RMS, or a 4kV HBM ESD event wouldn't you say?   

[floobydust]

Engineering is an applied science, we do TESTING. This is what safety standards are about as well.
Rather than sow confidence and certainty based on emotions or a psychological "feeling".

Multimeter incidents with arc flash do happen with most resolved out of court.  chinese products commonly have misleading, fraudulent claims about their agency approvals.
Do your own research and you will see that we (the West) allow this to continue and nothing can be done legally against them.

Example is a big name chinese manufacturer multimeter with purported 61010 approvals and arc flash happened in USA. It was found to have inadequate spacings amongst other bullshit.  It may have been only certified to the low voltage directive, as a 3V device not to be used over 50V input. This is another common loophole used.

[Aldo22]

Sure, there is a very wide variance of products available and I've looked at a few of them, including ANENG.   Suggesting a meter can handle 4kV without any proof or further details is useless, wouldn't you agree?   There is a reason I will state I test a meter at 4kV peak, 100us FWHH, 2 ohm source.  I may even show the waveform.  I want to be very clear about what I am subjecting them to.   There is a big difference between that and say 4kV AC RMS, or a 4kV HBM ESD event wouldn't you say?

I don't understand much about it and I'm not particularly interested in anything above 30V.
You can watch the video. I don't know how much sense it makes what he does.
Apparently the device survives the test though.

https://youtu.be/dAN96tYoe3c?t=4251

But I'll say it again, I don't do that sort of thing and I would not recommend an AN870 for high voltage.
Please let's not have this pointless discussion again.

[joeqsmith]

Sure, there is a very wide variance of products available and I've looked at a few of them, including ANENG.   Suggesting a meter can handle 4kV without any proof or further details is useless, wouldn't you agree?   There is a reason I will state I test a meter at 4kV peak, 100us FWHH, 2 ohm source.  I may even show the waveform.  I want to be very clear about what I am subjecting them to.   There is a big difference between that and say 4kV AC RMS, or a 4kV HBM ESD event wouldn't you say?

I don't understand much about it and I'm not particularly interested in anything above 30V.
You can watch the video. I don't know how much sense it makes what he does.
Apparently the device survives the test though.

https://youtu.be/dAN96tYoe3c?t=4251

But I'll say it again, I don't do that sort of thing.

LOL.  Ok, I suspect even the harbor freight meter would have no problems with what he is showing. 

[Simmed]

hmmm in the foil wrapped video part
parts of the test leads are wrapped, his leakage is over 70uA @ 4kV

as comparison
long ago i tested some PTFE twisted pair cable (about 24AWG) 1m length with 1kV and it has around 10ish uA leak
first i would question, is his test lead rated for 4kV ? i think most are only 1kV
so i dont know about what to concur from the video

Sure, there is a very wide variance of products available and I've looked at a few of them, including ANENG.   Suggesting a meter can handle 4kV without any proof or further details is useless, wouldn't you agree?   There is a reason I will state I test a meter at 4kV peak, 100us FWHH, 2 ohm source.  I may even show the waveform.  I want to be very clear about what I am subjecting them to.   There is a big difference between that and say 4kV AC RMS, or a 4kV HBM ESD event wouldn't you say?

I don't understand much about it and I'm not particularly interested in anything above 30V.
You can watch the video. I don't know how much sense it makes what he does.
Apparently the device survives the test though.

https://youtu.be/dAN96tYoe3c?t=4251

But I'll say it again, I don't do that sort of thing and I would not recommend an AN870 for this.
Please let's not have this pointless discussion again.

* as a curious search online
medical device rated power should not leak more than 1mA (iec-60601)
but this is a test meter, do they have a leak limitation test criteria like medical / iec code ?

[Aldo22]

first i would question, is his test lead rated for 4kV ? i think most are only 1kV

If these are the ones supplied, then they are rated 1000V.

so i dont know about what to concur from the video

Actually I don't either. I picked up the video and thought “cool 4kV”, but the more I think about it, the less I know what to conclude.
The DMM is also apparently switched off during the test...

Best to forget about it. 

[joeqsmith]

I think I did something similar early on to look at insulation.  I don't think what he is showing is wrong, but I am more interested in conducted susceptibility.  This is why I constantly state my interest in IEC 61326.

[joeqsmith]

Dave made a video once where he was cycling some device with his power supply and damaged it.  I wasn't able to find that video but maybe this would be of some interest.   

https://youtu.be/hReCPMIcLHg?t=843

***
Found it.  Watch the first 2 minutes.   It's good to have tools that are robust enough to survive some basic transients.  But to your point, if you are just measuring your AA batteries and 1k resistors,  none of this matters. 

[Aldo22]

Dave made a video once where he was cycling some device with his power supply and damaged it.

Interesting video. 
What can I learn from it?
"Expensive devices will also break, better buy cheap ones to be less annoyed"? 
Yes, expensive is relative, but you can get 10 DPS-150 for one DP832 (no, I don't really want to compare these devices).

But to your point, if you are just measuring your AA batteries and 1k resistors,  none of this matters. 

Exactly! 
In the attachment you can see my super cheap “Lab” with DPS-150 trying to measure a 0.1Ω resistor.
19.188mV / 190.52mA = 0.1007Ω
A bit awkward, but it works.
This is my little world. Everything fits into a drawer. 

[Fungus]

Dave made a video once where he was cycling some device with his power supply and damaged it.

Interesting video. 
What can I learn from it?

That even the little 5V coil inside a relay can destroy things if you're not careful.

[Aldo22]

That even the little 5V coil inside a relay can destroy things if you're not careful.

Sure, but if it happens to an experienced David L. Jones, it can happen to anyone.
The only question then is, how expensive the damage is.