Why do you think measuring equipment and safety ratings were invented in the first place? Because better men and women than us paid the price for not having them. I don't think anyone expects a hobbyist to work on industrial equipment. However, the gear should be safe with anything commonly and reasonably found inside the home. That includes poking the mains with a meter apparently rated to do so.
We should also take into account that people are forgetful. Even if you know a meter is unsafe for anything but low voltage now, will you still know when you pick it up in 5 years, when the hobby has died off but the multimeter is still around? Will a random family member?
Using an isolation transformer is the most patently unsafe thing a hobbyist can do! Period!
So, you float your scope and hook up one probe with its ground connection to some elevated voltage difference. Even the ground lead is elevated from earth ground. As is the scope and it's BNC connectors. Now, when you go to clip in the ground lead of the second scope, OOPS!, it isn't at ground when you touch it. It isn't necessarily going to connect to an identical voltage as the first probe. That's the second OOPS! You probably can't take simultaneous elevated differential measurements unless there is a common, but not grounded, reference point.
This is a huge accident waiting to happen. At best, if then, this should be done by professionals. As a 60 year amateur, I still don't have such a transformer and I have yet to see a need for such a thing.
The scope has an A-B function that is likely to be entirely adequate for differential measurements. And the scope can stay grounded!
I find it amazing that you have worked 60 years and never come across a situation where an isolation transformer was necessary. But I don't know what kind of gear you work on...
Any CAT II meter should be fully qualified for residential (family member) work. CAT II is so low on the totem pole that it is almost always a 'lesser included' with some CAT III rating. Neither are going to survive a lighting strike on the pole at the end of my driveway.
I'll concede that the ratings are probably bogus on any meter not labelled FLUKE.
Really, the safe bet is to only recommend UL Listed CAT IV 1000V meters. I don't know if anybody makes one because all I see are CAT IV 600V but still... But it only counts if the meter is UL Listed or ETL Listed. CE Mark doesn't mean spit.
Another thought: Just because a person knows a little electronics and is fully qualified to blink an LED with an Arduino doesn't mean they should be working on mains. Clint Eastwood said it best: "A man has to know his limitations!".
The problem with multimeters is that they are so simple to operate. So simple, in fact, that many users don't stop to THINK. Meters should power up with THINK on the screen!
Using an isolation transformer is the most patently unsafe thing a hobbyist can do! Period!
CATII is for use in anything in a house that is farther than 10 meters from the distribution panel. How many outlets are that far in your house?
I'll concede that the ratings are probably bogus on any meter not labelled FLUKE.
Yeah right. Amrpobe, Keysight, Brymen, Hioki, etc. are all lying.
Really, the safe bet is to only recommend UL Listed CAT IV 1000V meters. I don't know if anybody makes one because all I see are CAT IV 600V but still... But it only counts if the meter is UL Listed or ETL Listed. CE Mark doesn't mean spit.
Brymen makes CATIV 1000V meters. The Amprobe HD series are also rated the same. These ratings are not needed. I am happy to see meters having CATIII 600V or even 300V for home users.
Another thought: Just because a person knows a little electronics and is fully qualified to blink an LED with an Arduino doesn't mean they should be working on mains. Clint Eastwood said it best: "A man has to know his limitations!".
People keep saying this, "A beginner needs to know". How does a beginner know? What in the word "beginner" means "with experience to know your limitations"?
The problem with multimeters is that they are so simple to operate. So simple, in fact, that many users don't stop to THINK. Meters should power up with THINK on the screen!
So you are saying that even non-beginners need some help in their equipment to mitigate harm?
The EEVblog Brymen BM235 is UL Listed to 300V CAT IV, 600V CAT III and 1000V CAT II. But it is UL Listed and the logo is on the face of the meter. Note that it isn't suitable for working on 480V 3 phase switchgear.
The Brymen BM869s, for example, claims 1000V CAT IV but shows no sign that it is UL Listed. It has great specs but they aren't confirmed by an independent laboratory AFAICT. Perhaps the logo is on the back of the case. I didn't see anything about listing in the manual. I might have missed it...
The EEVblog Brymen BM235 is UL Listed to 300V CAT IV, 600V CAT III and 1000V CAT II. But it is UL Listed and the logo is on the face of the meter. Note that it isn't suitable for working on 480V 3 phase switchgear.
The Brymen BM869s, for example, claims 1000V CAT IV but shows no sign that it is UL Listed. It has great specs but they aren't confirmed by an independent laboratory AFAICT. Perhaps the logo is on the back of the case. I didn't see anything about listing in the manual. I might have missed it...
All Brymens are UL listed.
You are correct! I got onto their page from a different direction and they clearly show UL for the entire range. It's odd that they don't put the logo on the front like they do for the BM235.
Given the UL Listing, the ratings have been tested and are real.
http://www.brymen.com/PD02BM860s_869s.html
It's odd that they don't put the logo on the front like they do for the BM235.
Using an isolation transformer is the most patently unsafe thing a hobbyist can do! Period!
Here is why
And let's not forget the flimsy things on several cheap DMM strangely combined with CAT III or even CAT IV labels: 250V fuses for 600V mesurements, flimsy connectors and cables to carry up to 10A a.s.o.
So if you know, what you're doing everything is fine, even with a cheapo DMM; if you're doing really really wrong, I wouldn't rely on the protection measures of a Fluke either.
...[snip]...get some decent silicone cables and probes which can be called like that; I personally like Hirschmann probes and cables.
And let's not forget the flimsy things on several cheap DMM strangely combined with CAT III or even CAT IV labels: 250V fuses for 600V mesurements, flimsy connectors and cables to carry up to 10A a.s.o.Definitely.
Some meters might actually handle 600V on voltage function only, but 250V on all current measurements. The user must pay attention to such details, as some will list this on the front panel in some manner, to not at all (where teardowns really come in handy ).So if you know, what you're doing everything is fine, even with a cheapo DMM; if you're doing really really wrong, I wouldn't rely on the protection measures of a Fluke either.True, as CAT ratings are there to protect the user (up to a point), not the meter.
Exceed the CAT specs' transient/surge voltage rating however, and even the best name brands can become a grenade....[snip]...get some decent silicone cables and probes which can be called like that; I personally like Hirschmann probes and cables.Good advice.
Most of my stuff is Probemaster as I find it to offer a better deal than other quality brands based on US pricing, but I'd trust Hirschmann, Mueller, Cal Tech, or Pomona/Fluke as a general rule. Shame Oldaker Mfg. Corp.'s plant burnt down, causing them to fold (nearly identical to Probemaster, down to the Softie probe body; some info here).
FWIW, there's Fluke TL71 test leads available on eBay for $6.99 shipped (silicone insulation & rated for 10A). According the member that initially linked these (and has tested them), they're suspected to be genuine units made for the Chinese market.
Here's the last Oldaker Catalog (.pdf) I could find for those interested. No Softies pictured, but its solid red & black ergonomic bodied predecessor is (photo on first page). BTW, Probemaster used this same body prior to the current Softie body on the 8000 series' stuff as well. Perhaps Probemaster was one of their suppliers as Mueller was.
I think we all scared the OP away. He posted once and has never responded. I sent him a PM and he has not responded. I tried to get people to get back on track for his original question and even started a thread to divert this kind of argument away from here. C'mon people, why do we always have to dog pile on a thread and piss off the beginners?
Can you link to the post or thread that mentions those Fluke leads?
Most of my stuff is Probemaster as I find it to offer a better deal than other quality brands based on US pricing, but I'd trust Hirschmann, Mueller, Cal Tech, or Pomona/Fluke as a general rule. Shame Oldaker Mfg. Corp.'s plant burnt down, causing them to fold (nearly identical to Probemaster, down to the Softie probe body; some info here).
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BTW, Probemaster used this same body prior to the current Softie body on the 8000 series' stuff as well. Perhaps Probemaster was one of their suppliers as Mueller was.
About U.S. Probes :
We are Oldaker Mfg Corp DBA US Probes On-Line Distributor. However Oldaker had a fire and is no longer in business. So we have added Mueller & Probe Master to our line to try and continue to serve your needs.