Big Clive's "Trashy" meter, unboxed ( Duratool D03047 multimeter )

[Fungus]

FFS, the division between the categories has to be placed somewhere.

Either that or ... eliminated?

Just switch everything to "CAT III", job done.

[xrunner]

I'm brushing up on these CAT ratings because I haven't thought about it for a while, and because I think I'll try to explain them to some of the local hams who don't know what it all means (I can practically guarantee that).

I get the divisions between them, but I can't find what they define as a "transient". Is there a definition for "transient" as pertains to the CAT ratings? Yes the transient is a voltage spike bit for how long?

[joeqsmith]

Every mains socket outlet is CAT III, ...

Provide a reference in any of the IEC standards from any country that states that. 

Have you got any plans to torture test any bench meters? Unless I missed it I haven't seen any so far from you. I'd be really curious to see what you find

While I understand the responses about the bench meters and CAT ratings, I assume you are asking from the standpoint of how robust they are and not about safety.   It's certainly a valid thought.   My first Fluke was the perfect example of how not to design a robust meter.  I damaged it more than once with very low level transients.  When looking for something to replace it, I spoke with a friend who worked at  HP.   They use GDTs and other clamps on the front end to protect the sensitive circuits.  I bought two different ones new and never looked back.   In all the years I have owned the HP34401A, the only time it was damaged was during a lightning storm where we took a hit.   I made a video of my repairs.

I haven't looked at new bench meters in a long time.  The few I have would have cost far more than the Gossen Ultra I looked at.   I have an old Fluke 8506 that would have been over $10k new, back when it was made.   You could spend $100k in a shootout.   The high costs would mean turning to advertising and other funding.   This isn't something I have considered. 

When running these benchmarks, one of the common feedbacks received was from people who saw no value in the testing and see it as a waste of money.  I appreciate that they were concerned about my personal finances but you can imagine the whining when you start to burn down more than someone makes in a year in one video.      

[Black Phoenix]

Well the way I was teached some years ago regarding the CAT rankings were the following:

CAT l - Electronics (<= 48V);
CAT II - Single Phase outlets and connected equipments;
CAT III - Three-phase distribution and connected equipments;
CAT lV - Three-phase at utility connection (meter head), any outdoor conductors (buried or not).

[IanB]

Are bench meters supposed to be robust? In my mind I think of them as sensitive, delicate, precision instruments, things to be treated with care. Would you expect an expensive Mitutoyo micrometer to survive being chucked in a tool drawer?

Are you talking about drop tests etc? I'm talking about surges/spikes/overload conditions/etc

I'm making an analogy. A sensitive mechanical instrument should be treated with mechanical care. Similarly, a sensitive electrical instrument should be treated with electrical care.

[Someone]

Every mains socket outlet is CAT III, ...

Provide a reference in any of the IEC standards from any country that states that.

I quoted the AS61010 standard in the other thread that this has split into. Not having any of the international examples to hand at the moment that will do, and you're free to provide quotes from others.

61010 measurement categories are really simple:
"CAT III is for measurements performed in the building installation"

Good luck trying to argue that a mains socket affixed to the wall is something other than the building installation. But we have several people trying to be "clever" and say either side of the socket outlet should be treated the same, when the standard says that is the point of distinction.

[Someone]

Well the way I was teached some years ago regarding the CAT rankings were the following:

CAT l - Electronics (<= 48V);
CAT II - Single Phase outlets and connected equipments;
CAT III - Three-phase distribution and connected equipments;
CAT lV - Three-phase at utility connection (meter head), any outdoor conductors (buried or not).

Well, you were taught incorrectly. Phase count is irrelevant, and CAT I is far more specific than a voltage limit.

[EEVblog]

FFS, the division between the categories has to be placed somewhere.

Either that or ... eliminated?
Just switch everything to "CAT III", job done.

Yeah, I don't know why anyone would be pedantic over the exact delineation. If you are working on anything mains related, get at least a certified 600V CAT III meter. It's not like they are expensive. The Fluke 101/113, almost any Brymen, and there are plenty of other options in higher feature capability meters.
Industrial plant techs should consider using a 600V CAT IV meter.
If you are using a CAT II only meter then you don't really care about mains or CAT rating, it's just a multimeter.

[David Aurora]

Every mains socket outlet is CAT III, ...

Provide a reference in any of the IEC standards from any country that states that. 

Have you got any plans to torture test any bench meters? Unless I missed it I haven't seen any so far from you. I'd be really curious to see what you find

While I understand the responses about the bench meters and CAT ratings, I assume you are asking from the standpoint of how robust they are and not about safety.   It's certainly a valid thought.   My first Fluke was the perfect example of how not to design a robust meter.  I damaged it more than once with very low level transients.  When looking for something to replace it, I spoke with a friend who worked at  HP.   They use GDTs and other clamps on the front end to protect the sensitive circuits.  I bought two different ones new and never looked back.   In all the years I have owned the HP34401A, the only time it was damaged was during a lightning storm where we took a hit.   I made a video of my repairs.

I haven't looked at new bench meters in a long time.  The few I have would have cost far more than the Gossen Ultra I looked at.   I have an old Fluke 8506 that would have been over $10k new, back when it was made.   You could spend $100k in a shootout.   The high costs would mean turning to advertising and other funding.   This isn't something I have considered. 

When running these benchmarks, one of the common feedbacks received was from people who saw no value in the testing and see it as a waste of money.  I appreciate that they were concerned about my personal finances but you can imagine the whining when you start to burn down more than someone makes in a year in one video.   

Exactly, my question was kind of a sidenote (I probably should have just PM'd it in retrospect). I figured the insane cost was probably one of the main stumbling blocks, haha. But yeah- my curiosity was definitely about how the input stages of various models might cope when things go wrong. Which really circles back to the cost thing as well- for the price of some of those things it'd be great to know how well protected (or not) various models are.

[David Aurora]

Are bench meters supposed to be robust? In my mind I think of them as sensitive, delicate, precision instruments, things to be treated with care. Would you expect an expensive Mitutoyo micrometer to survive being chucked in a tool drawer?

Are you talking about drop tests etc? I'm talking about surges/spikes/overload conditions/etc

I'm making an analogy. A sensitive mechanical instrument should be treated with mechanical care. Similarly, a sensitive electrical instrument should be treated with electrical care.

You're kind of making the same mistaken assumption as the OP here that everything is always controllable- it's not. Devices fail while under test, surges happen, test points can be mislabeled, probing mistakes happen, etc.

[IanB]

I'm making an analogy. A sensitive mechanical instrument should be treated with mechanical care. Similarly, a sensitive electrical instrument should be treated with electrical care.

You're kind of making the same mistaken assumption as the OP here that everything is always controllable- it's not. Devices fail while under test, surges happen, test points can be mislabeled, probing mistakes happen, etc.

There's no mistaken assumption here. If you drop your expensive micrometer on the concrete floor and put it out of alignment, that's tough on you, time to buy a new one. Similarly, if you blow up your expensive bench meter by accident, that is similarly tough on you. Time to replace it or get it repaired. What you don't do is get the probes from that expensive meter and recklessly stick them in unknown circuits. If you do that you have only yourself to blame for mishaps.

[joeqsmith]

Every mains socket outlet is CAT III, ...

Provide a reference in any of the IEC standards from any country that states that.

I quoted the AS61010 standard in the other thread that this has split into. Not having any of the international examples to hand at the moment that will do, and you're free to provide quotes from others.

61010 measurement categories are really simple:
"CAT III is for measurements performed in the building installation"

Good luck trying to argue that a mains socket affixed to the wall is something other than the building installation. But we have several people trying to be "clever" and say either side of the socket outlet should be treated the same, when the standard says that is the point of distinction.

My home has a tiny little service coming into from a small distribution transformer.  Nothing like what feeds for the buildings where I worked.    Outlets at my house are several feet from the main feed and are behind small CBs which are behind another small one.  Worse thing that will happen if I pull an outlet and short the wires, I blow a CB.  Hardly CAT III or risk of an arc flash.       

Even at work where we have larger services to plug into, it's a long way from the main lines and again fed though various CBs.  Lots to limit the current.  Some of the larger factories I have worked will have their own distribution systems outside in fenced areas.   

I'm not going to get all concerned about my home toaster repairs and my CAT III outlets because it's just not the same thing.  If I have to go into the field, I have equipment for that. 

[EEVblog]

Exactly, my question was kind of a sidenote (I probably should have just PM'd it in retrospect). I figured the insane cost was probably one of the main stumbling blocks, haha. But yeah- my curiosity was definitely about how the input stages of various models might cope when things go wrong. Which really circles back to the cost thing as well- for the price of some of those things it'd be great to know how well protected (or not) various models are.

The robustness of bench meters is effectively stamped on the front. Both of mine (Keithly and Keysight) are CAT II 300V. That screams "I'm delicate please don't hurt me!"
No need for testing, just assume all bench meters are delicate snowflakes.

[xrunner]

Some of my bench meters:

GW Instek GDM-8251A

CAT I 1000V
CAT II 600V

Rigol DM3058E

CAT II 600V

Others such as hp 34401a and older bench meters don't specifically state CAT on the front panel (but may in the manual I haven't looked yet).

[joeqsmith]

The robustness of bench meters is effectively stamped on the front. Both of mine (Keithly and Keysight) are CAT II 300V. That screams "I'm delicate please don't hurt me!"
No need for testing, just assume all bench meters are delicate snowflakes.

Or test them to a common standard and see how they shake out which is what David is asking about.   No big deal to benchmark them.   

[Someone]

Every mains socket outlet is CAT III, ...

Provide a reference in any of the IEC standards from any country that states that.

I quoted the AS61010 standard in the other thread that this has split into. Not having any of the international examples to hand at the moment that will do, and you're free to provide quotes from others.

61010 measurement categories are really simple:
"CAT III is for measurements performed in the building installation"

Good luck trying to argue that a mains socket affixed to the wall is something other than the building installation. But we have several people trying to be "clever" and say either side of the socket outlet should be treated the same, when the standard says that is the point of distinction.

My home has a tiny little service coming into with a small distribution transformer.  Nothing like the feeds for the buildings where I worked.    Outlets at my house are several feet from the main feed and are behind small CBs which is behind another small one.  Worse thing that will happen if I pull and outlet and short the wires, I blow a breaker.  Hardly CAT III or risk of an arc flash.       

Even at work where we have larger services to plug into, it's a long way from the main lines and again fed though various CBs.  Lots to limit the current.  Some of the larger factories I have worked will have their own distribution systems outside in fenced areas. 

I'm not going to get all concerned about my home toaster repairs and my CAT III outlets because it's just not the same thing.

So what's the supply impedance at those socket outlets? Because over here we do see impedances at the outlets low enough in residential installations to require >1kA breaking capacity in a meter hence the need for at least CAT II for mains connected devices. I've not worked on or measured a high current residential supply with lower impedances, but with electrification of vehicles they will become more common and then you're into the CAT III fault currents (100A 2% droop) before considering transients/faults.

Yes, it may well be that there is no need for the higher ratings of CAT III somewhere (or anywhere) between the socket outlet and the supply feeder in your installation, that will vary from location to location. I'm not disagreeing with that but the standards have to cover a huge range of possible situations and almost (but not guaranteed) worst cases so most real world examples will be far below the limits. The standard is a way to have a quickly and easily understood delineation point, which you and others are going to great lengths to try and muddy/blur/confuse for some unknown reason.

[IanB]

I have a small question for everyone in this thread: do your lightbulbs have a CAT rating on them? When you twist a bulb into its socket, do you ever worry about it exploding in your hand? Do you wear safety glasses and rubber shoes when you change a lightbulb?

A DMM may be connected to the mains for a few seconds at a time to take a reading, and there is only one of them. All the lamps in your house are connected to the mains 24/7 and switched on for hours at a time. They could explode, cause a fire, or cause human injury. The risk is vastly higher than with using a DMM.

Why are there many threads about meters, and no threads about household appliances and electrical devices? There are millions more of the latter, and a proportionately higher hazard, statistically.

[EEVblog]

Why are there many threads about meters, and no threads about household appliances and electrical devices? There are millions more of the latter, and a proportionately higher hazard, statistically.

Because engineers like to nitpick about test equipment.

[EEVblog]

The robustness of bench meters is effectively stamped on the front. Both of mine (Keithly and Keysight) are CAT II 300V. That screams "I'm delicate please don't hurt me!"
No need for testing, just assume all bench meters are delicate snowflakes.

Or test them to a common standard and see how they shake out which is what David is asking about.   No big deal to benchmark them.   

Sure, but I'd bet few people would care. It's not like you'd use that as a buying decision for a 4 digit priced bench meter.
And if you thought there are a lot of people complaining about blowing up DMM's is pointless, wait until you blow up expensive high end bench meters.
But hey, knock yourself out.

[Someone]

I have a small question for everyone in this thread: do your lightbulbs have a CAT rating on them? When you twist a bulb into its socket, do you ever worry about it exploding in your hand? Do you wear safety glasses and rubber shoes when you change a lightbulb?

A DMM may be connected to the mains for a few seconds at a time to take a reading, and there is only one of them. All the lamps in your house are connected to the mains 24/7 and switched on for hours at a time. They could explode, cause a fire, or cause human injury. The risk is vastly higher than with using a DMM.

I wouldn't change a light bulb unless the switch is turned off, no I don't tag out or prove the circuit de-energised but that works 99.999% of the time (yes I have been shocked from that approach and faulty power switch). Equally I wouldn't put my face near a lamp when powering it on for the first time, proximity to a handheld multimeter is generally very different.

Electrical fires in appliances/cabling, yep that happens more often.

[floobydust]

I have a small question for everyone in this thread: do your lightbulbs have a CAT rating on them? When you twist a bulb into its socket, do you ever worry about it exploding in your hand? Do you wear safety glasses and rubber shoes when you change a lightbulb?

A DMM may be connected to the mains for a few seconds at a time to take a reading, and there is only one of them. All the lamps in your house are connected to the mains 24/7 and switched on for hours at a time. They could explode, cause a fire, or cause human injury. The risk is vastly higher than with using a DMM.

Why are there many threads about meters, and no threads about household appliances and electrical devices? There are millions more of the latter, and a proportionately higher hazard, statistically.

Appliances have a legal path to a manufacturer, whereas many chinese multimeters have none. Appliances, "electrical devices", light bulbs have lots of room for HV spacings. Small handheld multimeters have no room for reasonable clearances and sized fuses. They are used generally close to your face and hands with exposed wires.

The issue is cheap chinese multimeters with fake/spoofed safety claims and zero evidence of any testing.
They need to stop this horseshit. It just fuels threads like this spinning around the requirements amidst unknown capabilities of the product. Because they can and do involve measurements needing some trust of the numbers- yet they command zero trust for safety, having no evidence of testing or any formal vouching.
We know SFA about the DT830's abilities or design, and there are dozens of variants.
A simple question about suitability for measuring 240VAC mains is a guessing game. People soon will be using these on electric cars and she'll be right.

[Fungus]

Why are there many threads about meters, and no threads about household appliances and electrical devices? There are millions more of the latter, and a proportionately higher hazard, statistically.

There's also similar lack of discussion about wearing gloves+gumboots and going outside to look at the sky before you use your multimeter on mains.

It just never comes up. 

[Fungus]

My home has a tiny little service coming into from a small distribution transformer.  Nothing like what feeds for the buildings where I worked.    Outlets at my house are several feet from the main feed and are behind small CBs which are behind another small one.  Worse thing that will happen if I pull an outlet and short the wires, I blow a CB.  Hardly CAT III or risk of an arc flash. 

Same here. That's why I wasn't worried about measuring the mains with my Big Clive special.

Knowledge is power.

[Fungus]

Well, you were taught incorrectly.

Don't be too hard on him. Even Fluke corporation is confused by these 'standards'.

[Fungus]

And if you thought there are a lot of people complaining about blowing up DMM's is pointless, wait until you blow up expensive high end bench meters.

I think joe secretly enjoys the complaints. 

you can imagine the whining when you start to burn down more than someone makes in a year in one video.   

Maybe you could be the whistlindiesel of the test gear world.

Go big or go home...