Products > Test Equipment
Big Clive's "Trashy" meter, unboxed ( Duratool D03047 multimeter )
joeqsmith:
--- Quote from: switchabl on April 25, 2023, 04:43:28 pm ---...
Nowadays, the definition of the measurement categories has been moved to IEC 61010-2-030 and -033 and there is now only CAT II, III and IV as well as "equipment without a rated measurement category" (used to be CAT I). I suspect that the designation CAT I was removed because it was found to be confusing/inconsistent.
--- End quote ---
I don't believe that's something new. Even in EVS-EN 61010-2-033:2012 it was replaced with
--- Quote ---O: Other circuits that are not directly connected to MAINS
--- End quote ---
, but I continue to see papers published that refer to CAT I.
Fluke's application note:
--- Quote ---ABCs of multimeter safety Multimeter safety and you
--- End quote ---
for example states:
--- Quote ---CAT I Electronic • 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 highwinding
resistance transformer, such as the high-voltage
section of a copier
--- End quote ---
With different countries all having their own twist on these standards (I assume to leverage for import export) the may not use the same definitions.
If I were repairing toasters, I wouldn't be too concerned. Even in the previous post, the fact they were mentioning plugging into mains tells me something.
Fungus:
--- Quote from: IanB on April 25, 2023, 05:02:02 pm ---My impression is that although the bang and the flash can be quite exciting, the main danger is likely to be flying shrapnel hitting your eyes, and therefore the most useful item of PPE would be safety glasses.
--- End quote ---
The bang and flash could easily make you fall off a ladder. Or make you step backwards and put your foot in the bucket.
--- Quote from: IanB on April 25, 2023, 05:02:02 pm ---I don't recall much mention of that in this thread
--- End quote ---
You never will. The nannies assume that simply owning a yellow meter is sufficient protection. No gumboots needed.
--- Quote from: joeqsmith on April 25, 2023, 07:20:59 pm ---I continue to see papers published that refer to CAT I.
--- End quote ---
It's a useful designation. The "other" category still needs a name.
Roman numerals don't have zeros so maybe they could have renamed it "CAT X".
--- Quote from: switchabl on April 25, 2023, 04:43:28 pm ---I suspect that the designation CAT I was removed because it was found to be confusing/inconsistent.
--- End quote ---
Me? I'd have picked CAT II as the "useless" category.
a) A single piece of wire can be CAT II at one end and CAT III at the other. It doesn't get much more "confusing/inconsistent" than that. :scared:
b) Is there a real job where you only ever work at CAT II level and never at CAT III?
switchabl:
--- Quote from: joeqsmith on April 25, 2023, 07:20:59 pm ---
--- Quote from: switchabl on April 25, 2023, 04:43:28 pm ---...
Nowadays, the definition of the measurement categories has been moved to IEC 61010-2-030 and -033 and there is now only CAT II, III and IV as well as "equipment without a rated measurement category" (used to be CAT I). I suspect that the designation CAT I was removed because it was found to be confusing/inconsistent.
--- End quote ---
I don't believe that's something new. Even in EVS-EN 61010-2-033:2012 it was replaced with
--- Quote ---O: Other circuits that are not directly connected to MAINS
--- End quote ---
, but I continue to see papers published that refer to CAT I.
--- End quote ---
Yes, I just checked and DIN-EN 61010-1:2002 defines "measurement category I" (while 2010 does not). IEC 61010-2-033 didn't even exist back then, multimeters were covered by the general norm. I feel old now.
It's certainly true that it has stuck around. You even get new products with "CAT I" markings, even though AFAIK you were never really supposed to do that even back then (terminals with measurement category I are supposed to be labelled with the voltage rating, only the higher categories should have "CAT x" printed next to them).
What I hope people take away from this:
- CAT II, III, IV have very specific meanings in terms of overvoltage protection
- "CAT I" just means "not supposed to be connected directly to a mains circuit"; there may or may not be additional protection beyond the rated voltage, check the manual
If someone decides not to follow safety standards that is fine by me (as long as they do not endanger anyone else). I just think that this should be a conscious decision, not a result of ignorance or misinformation.
--- Quote from: Fungus on April 25, 2023, 09:30:47 pm ---Me? I'd have picked CAT II as the "useless" category.
a) A single piece of wire can be CAT II at one end and CAT III at the other. It doesn't get much more "confusing/inconsistent" than that. :scared:
b) Is there a real job where you only ever work at CAT II level and never at CAT III?
--- End quote ---
a) The difference between CAT II - IV circuits is basically all wiring (which adds impedance) and usually a fuse or circuit breaker somewhere between each level.
Anyway, the level of protection for CAT II is clearly defined and it means the same on any meter, whether you find it useful or not. The problem with CAT I was that is just says "could mean anything, read the manual".
b) Yes, anyone repairing or developing mains-powered electronics or appliances will usually need CAT II only (CAT III is for electricians).
David Aurora:
--- Quote from: Fungus on April 25, 2023, 11:58:15 am ---
--- Quote from: David Aurora on April 25, 2023, 11:24:56 am ---You keep banging on about how these things work just fine at high voltages, then when you get called out you backtrack and claim you never said they were suitable for it.
--- End quote ---
Rubbish.
I said they were suitable for high voltage, and I stand by that. Pictures have been posted of a worse meter than this measuring 1100V in somebody's hand.
(I notice you don't go after joe...)
I also said they weren't suitable for high energy. If you can't understand the difference between the two then you're in no position to lecture anybody on safety.
This meter is CAT I 500V rated. I think that's a correct rating and said so in the very first post, anything else is just your imagination.
End of.
--- End quote ---
Right, because Joe clearly knows what he's talking about and also clearly knows the difference between safety based on knowledge and safety based on wilful ignorance.
Again, you're playing word games with voltage/energy as if there's no relation. A high voltage/low energy circuit can become a lethally high energy circuit pretty damn quickly under all sorts of fault or user error conditions. A correctly set meter being tested under controlled conditions with a sample size you can count on one hand is not an endorsement of a meter being suitable for use at high voltage.
Do what you want in your own time, but if you're gonna carry on on the internet about a poorly constructed hobbyist meter being suitable for high voltages be prepared for disagreement.
joeqsmith:
--- Quote from: switchabl on April 25, 2023, 10:10:52 pm ---I feel old now.
--- End quote ---
You and me both!
--- Quote from: switchabl on April 25, 2023, 10:10:52 pm ---What I hope people take away from this:
- CAT II, III, IV have very specific meanings in terms of overvoltage protection
--- End quote ---
As a general observation, meters that have been certified to the 61326 EMC standards do well against my tests. The protection is a dice roll as what it even means. Protect the meter, protect the operator, both... Manufactures don't agree. I was interested in finding meters that would not be damaged when subjected to a few basic transients. It doesn't really fit with the IEC standards and why I rolled my own generator. I wanted something like the 6100-4-5 surge but limited. So I dropped the combo, followed the open circuit voltage waveforms, ignored the short circuit current and limited it to about 20J. Depending on the generator, I used a 50 or 100us FWHH and stayed with a 2 ohms source across the board.
We did have a member how stepped up and ran a new Fluke 101 on a real combo generator after I tested that first one. Crazy how robust these things are. That was Fungus's contribution as I would have never purchased another Fluke otherwise as I was still pissed at them a few decades later for designing such a weak meter (8000A). :-DD
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