Why CAT ratings are so important AND safe practises

[TheNewLab]

Hi I found this you tube video that i happened across that made me think of all the CAT ratings dialogue and Dave's discussion on it

Here is the Link:

[Assafl]

This is what happened to the CatIV 600V rated Fluke.



There is this "below the radar" trend on EEVblog to tell beginners to get a CatIII or a CatIV Expensive (called by proponents "independently certified") DMMs and that these DMM will "save them" when they fool around probing in a wanton fashion (since they are beginners). Eddie was not a beginner (at least not according to the employees interviewed) but used his expensive Fluke on a >2000V 1200A starter equipment.

Carelessness is never rewarded by electricity. At best really expensive components release the magic smoke. At worst, the careless EE does. A careless beginner should take up sawing or embroidery. Or stick to "Arduino on Battery".

BTW - A regular, fused home circuit (15A, 20A, etc.) cannot sustain what took place there. Neither the current capability nor the voltage.
   
 

[Assafl]

There are good electricians, and there are dead electricians.

There are indeed electricians that did not have the mindset to be one.

There are also those that did 20 years in domestic installations and based on their certification were given employment at an industrial installation or utility (and needing a job did not approach their boss and admit to being terrified).

And then there are the really good, careful ones, that one time (too many) were in a hurry to get home (kids birthday, anniversary, etc.).

They are all dead... (with IEC60900 pliers and IEC61010 Cat IV rated Flukes spread around them).

[Jeroen3]

I often work around generators, floating my hands around 400V busbars. Because that is where the equipment is.
Fooling around with not-enough AWG cabling and on-the-edge breakers. No problem.
Please note: generators have a limited short circuit capability. Yet, enough to melt your banana leads in a seconds.

However I do not touch or open grid side switchgear. The grid has an infinite short circuit capability.

[Lightages]

CAT ratings are not safety.

User experience is not safety.

Being an idiot at any moment can end in tears.

Being careful, diligent, and follow training can save your life.

What do I mean by all of these statements? People make mistakes and safety ratings and procedures have been implemented to save you from your human stupidity. Follow check lists, procedures, and using proper equipment will reduce your risk to serious injury quite a bit. Unfortunately, making something idiot proof just produces better idiots. Sometimes luck just grabs you and you become the reason that safety standards get revised.

In the home, CATIII/300V is enough for equipment. The examples posted in this thread so far are outside of the hobbyist's domain. If you are poking things into the kinds of systems that have been demonstrated in this thread, then you have no business doing so unless you are a high voltage industrial electrician. This has nothing to do with home electronics or home electricity.

These images and videos illustrate the extremes of what can happen and perhaps provide caution. People should not just do something without thinking about the possible consequences.

That being said, hobbyists need to understand CAT ratings. IMHO, if you don't understand CAT ratings,  no hobbyist should buy a multimeter with less than a CATIII  300V unless they now why they don't need to. Full stop, opinion stated.

[Electro Detective]

There are good electricians, and there are dead electricians.

There are indeed electricians that did not have the mindset to be one.

There are also those that did 20 years in domestic installations and based on their certification were given employment at an industrial installation or utility (and needing a job did not approach their boss and admit to being terrified).

And then there are the really good, careful ones, that one time (too many) were in a hurry to get home (kids birthday, anniversary, etc.).

They are all dead... (with IEC60900 pliers and IEC61010 Cat IV rated Flukes spread around them).

They are all dead because it was  "only a job..." = wrong deadly attitude   

Had they taken a keen interest learning and understanding the power systems they worked on, qualified or not,
and been of a suspicious nature to not trust or assume anything,
they would be with their families and friends now and surfing EEVblog forum and Youtube 
instead of buried fried maggot fodder

 

[nctnico]

This is what happened to the CatIV 600V rated Fluke.

There is this "below the radar" trend on EEVblog to tell beginners to get a CatIII or a CatIV Expensive (called by proponents "independently certified") DMMs and that these DMM will "save them" when they fool around probing in a wanton fashion (since they are beginners). Eddie was not a beginner (at least not according to the employees interviewed) but used his expensive Fluke on a >2000V 1200A starter equipment.

Well, you can't fix stupid. He clearly used the wrong tool for the job. CAT rated doesn't mean indestructible but tested to certain limits. When working on 2000V you need equipment (CAT) rated for at least 2000V.

[Fungus]

There's other factors, too.

If you have kids at home, would you want them to copy dad and connect a DT830B up to a mains socket and turn the dial?

There is this "below the radar" trend on EEVblog to tell beginners to get a CatIII or a CatIV Expensive ...

I always tell people about the $42 (delivered) Fluke 101. That's not expensive.

I think the Fluke 87V is complete overkill for just about everything. $15 meters work fine for low voltage stuff, the 101 is great for household mains. Buy both and you can handle anything except industrial AC power for under $50.

Get an 87V if your job requires one, otherwise it's a luxury item. I'd never tell a newbie to buy one.

[CopperCone]

just give er a real quick tap with your hands

[b_force]

A re-post of a re-port of a re-port? 

So here we go again (and again, and again, and again)

You know the fun part about safety rules?
They are totally different in other countries.
So I guess 'what is considered being safe' is even very subjective 

[Fungus]

You know the fun part about safety rules?
They are totally different in other countries.

CAT ratings are international.

[nctnico]

A re-post of a re-port of a re-port? 

So here we go again (and again, and again, and again)

You know the fun part about safety rules?
They are totally different in other countries.
So I guess 'what is considered being safe' is even very subjective 

Wrong conclusion. Safety rules are usually very similar but can be different due to circumstances in a specific country. For example: there is no use for laws&regulations regarding winter tires if it never snows/freezes in a country.

[b_force]

You know the fun part about safety rules?
They are totally different in other countries.

CAT ratings are international.

Except china 

This topic is about CAT ratings & safe practices.
A CAT rating is part of something, but definitely NOT equal to safety.
Like other people already mentioned in this post.
I was referring to safety rules in general, which are (apparently) pretty subjective.

In the home, CATIII/300V is enough for equipment. The examples posted in this thread so far are outside of the hobbyist's domain. If you are poking things into the kinds of systems that have been demonstrated in this thread, then you have no business doing so unless you are a high voltage industrial electrician. This has nothing to do with home electronics or home electricity.

On this whole never ending (so it seems) debate.
This is the only proper response I have ever read! 
Most people won't even go any further than CATII or even CAT I .
A smart person always works with a (properly fused) isolation transformer 
(That way you will always work in CAT I conditions)

[b_force]

A re-post of a re-port of a re-port? 

So here we go again (and again, and again, and again)

You know the fun part about safety rules?
They are totally different in other countries.
So I guess 'what is considered being safe' is even very subjective 

Wrong conclusion. Safety rules are usually very similar but can be different due to circumstances in a specific country. For example: there is no use for laws&regulations regarding winter tires if it never snows/freezes in a country.

That definitely not a wrong conclusion.
You're now talking about a very specific case.
Obviously, I am talking about general stuff, so lets say wiring and how the fuse board/distribution board is being made.
Also things like grounding/earth switch.

Just compare what's being done and considered 'safe' in USA, AUS/NZ, NL, B (belgium), GER, UK and Spain for example (fill the list with more)
It's like a comedy show. Things that are even a standard procedure in one country, are absolutely a no go in others.

Anyway, the point are not the details, but the fact that there are significant differences.

[Z80]

As this is an electronics forum, CAT ratings are irrelevant.  Electronics is CAT I a mains socket is CAT II.  If you need a CAT III or CAT IV meter, you are no longer an electronics hobbyist.

[Fungus]

As this is an electronics forum, CAT ratings are irrelevant.  Electronics is CAT I a mains socket is CAT II.  If you need a CAT III or CAT IV meter, you are no longer an electronics hobbyist.

Electronics hobbyists don't build huge power supplies or Tesla Coils in their sheds?? 

[Z80]

As this is an electronics forum, CAT ratings are irrelevant.  Electronics is CAT I a mains socket is CAT II.  If you need a CAT III or CAT IV meter, you are no longer an electronics hobbyist.

Electronics hobbyists don't build huge power supplies or Tesla Coils in their sheds?? 

No they don't.  I know what you are trying to do but huge supplies & Tesla coils are not typical hobby projects.  If you build such things then you better know what you are doing 

[Fungus]

As this is an electronics forum, CAT ratings are irrelevant.  Electronics is CAT I a mains socket is CAT II.  If you need a CAT III or CAT IV meter, you are no longer an electronics hobbyist.

Electronics hobbyists don't build huge power supplies or Tesla Coils in their sheds?? 

No they don't.  I know what you are trying to do but huge supplies & Tesla coils are not typical hobby projects.

You must be new here.

OK, they're not "Instructibles-level" projects, but you're not on Instructibles, you're on EEVBLOG.

And... people who don't know what they're doing have all the more reason to get a real CAT-rated meter. 

[b_force]

And... people who don't know what they're doing have all the more reason to get a real CAT-rated meter. 

That's actually the wrong piece of advice.

People don't know what they are doing shouldn't even touch electronics, period.
Or only the very low voltage stuff (arduino 3V, 5V & 12V tops so to speak)

This is a typical example that an higher rating meter is actually going to do more harm than good.
Because untrained people think they are safe because of that rating.
Simple psychology how peoples minds work.

"It's all safe because the equipment said it was rated for it". 

Exactly the reason why people advocate against strict rules, but that people should use their brains.
If they don't (wanna) use their brains, just stay far away from it, don't even buy a meter!

[Z80]

As this is an electronics forum, CAT ratings are irrelevant.  Electronics is CAT I a mains socket is CAT II.  If you need a CAT III or CAT IV meter, you are no longer an electronics hobbyist.

Electronics hobbyists don't build huge power supplies or Tesla Coils in their sheds?? 

No they don't.  I know what you are trying to do but huge supplies & Tesla coils are not typical hobby projects.

You must be new here.

OK, they're not "Instructibles-level" projects, but you're not on Instructibles, you're on EEVBLOG.

And... people who don't know what they're doing have all the more reason to get a real CAT-rated meter. 

I see, you are one of those people.  Ok, you say we are on EEVBLOG so perhaps you want to list Dave's videos where he builds or reviews huge stuff and Tesla coils? No?  If you really feel strongly then you should contact UL and tell them electronics should not be listed as CAT I because clearly they don't know what they are talking about.

[Fungus]

I see, you are one of those people.  Ok, you say we are on EEVBLOG so perhaps you want to list Dave's videos where he builds or reviews huge stuff and Tesla coils?

Dave doesn't, the forum members do.

Show me a single one of Dave's multimeter teardowns where he doesn't talk about CAT ratings.

Look at his latest one - the Sanwa pocket meter. He goes into detail of the CAT rating and specifically says he doesn't want current measurement. He's said many times he doesn't want current ranges on meters that might be poked into a mains socket.

I know what you are trying to do

Me? You're the one trying to fit the word "hobbyist" into a tiny little box.

By any dictionary definition I'm only a hobbyist - nothing in my job description or CV has anything to do with electronics. Yes, I've built Tesla Coils.

[Cerebus]

As this is an electronics forum, CAT ratings are irrelevant.  Electronics is CAT I a mains socket is CAT II.  If you need a CAT III or CAT IV meter, you are no longer an electronics hobbyist.

Yes, this is an electronics forum. It is not exclusively a hobby electronics forum. There are a lot of professionals on here, some with some serious power systems chops. Even if it was purely hobbyist, just because your hobby ends at 5V and 40 mA don't assume everybody else's does.

[Assafl]

Huge power supplies above 240v/125kVA (the 125kVA exception) where an arc flash analysis must be made? That is more than a domestic feed  of 3~ 230v 60A. Let alone an apartment.

Or smaller than that.

CAT ratings 3 and above  are about Arc Flash sort of energies. The voltage rating is about the insulation.

One can only hope those in Industry above the exception know that indeed they are in mortal danger. Whereas those at home avoid the utility feed and the fuse box. 

[Z80]

Yes of course I am aware there are professionals here  and they already know what they are doing and are not the target of this discussion.  If you are a responsible adult and have the money to spare then buy whatever makes you happy, no issue with that.  I'm also well aware that Dave has a strong opinion on CAT and that is usually directed towards if they are likely to be real or fake.  Everyone is fully entitled to their view.  My view is this:  For electronics (and since this is a point of contention) I will define it as CAT I and CAT II only, ie low voltage circuit boards and domestic mains outlets.  If you want to play with big capacitor banks that is outside the scope and falls in the 'you know what you are doing' category.
Buying a meter because it has a CAT IV rating is nonsense.  There are more important criteria like accuracy, features, does it have max hold, a good continuity tester low current ranges, burden voltage, capacitor test etc.  High energy safety is low on my list because I won't ever need it.  It also irks me when beginners are directed towards expensive industrial meters for several reasons, notably: It gives a false sense of security and can lead to "I'm not sure if I should do this but..." moments.  Secondly, many moons ago when I was knee high to a grasshopper popping a 300mA fuse was a common occurence.  Not a problem, glass fuses (240V certified) are ten a penny and perfectly safe for low energy electronics and the mains.  I worry sometimes that a youngster could have a meter with expensive HRC fuses and being skint, cheap out and buy fake crap of Fleabay or just wrap a bit of wire round the lugs.  After getting bored and moving on to the next hobby, the meter ends up being sold and used in a real CAT III / CAT IV situation and that may not end well.

[Lightages]

There is also another point about CAT ratings here. They are important, but what is also important is how to know when the CAT rating is real on a meter and is not just a lie to sell more meters. This is probably why Dave always does an inspection of a meter to see if it is possible it could actually meet its rating. It can be obvious when it can't possibly meet the claim. It is not see easy to see if it actually does.

False CAT ratings are worse than none at all. A person might trust a meter to meet its CAT rating and have some big problems, kill the meter, or kill the DUT. A good example is the Uni-Trend UT61E. It was originally rated at CATIV 600V and CATIII 1000V. It is still sold this way world wide. It is a lie and could never meet these claims. The fuses are incorrect for this. There are other design considerations that don't meet the claims. There is a European version with GS certification. The fuses and input protection have been upgraded considerably but it is only rated at CATIII 300V and CATII 600V! In other words the falsely labelled one might fool someone into using it on the distribution panel  when it appears it couldn't even be safe to use in a wall socket in a house.

So CAT ratings are important. Education is more important but without education people only have CAT ratings to help guide them. Companies that lie about safety ratings of their products should be fined, and/or closed down.