I tried to resist commenting here but my weakness of character prevented me from remaining silent.
A few rules to LIVE by when working around lethal voltages with a DMM:
1) Above 240V, DO NOT USE A DMM!!!
2) Below 240V, USE A FLUKE!!!
3) Chinese DMM's & Brymens are fine for ELECTRONICS but NOT MAINS ELECTRICITY.
I have been shocked and burned several times in my life by 120V, 240V and burned by 25KV in older TV's and I can tell you that it is no fun.
As for NCV, as another poster before me has said, "NCV is just a convenient preliminary indicator, that's it." And, That's really it.
Sorry, I just couldn't help myself!
A bit late to that party, but I would like to say that above statements are quite biased and probably have to be interpreted what they really should express...
1) Above safety voltage, please be aware of what you are doing and follow proper procedure to ensure safe working. Here in germany this would mean, according to code: There are the so called "5 safety rules", that loosely translate to: 1) disconnect equipment, 2) make sure it can not accidentally connected again, 3) measure for absence of voltage. And for 3) according to code you HAVE to use a two-pole voltage tester to prevent misreadings and other accidents caused by improper usage of a DMM here. Synonym for this i germany is the brand name "Duspol":
https://www.benning.de/produkte/pruef-und-messtechnik/pruefgeraete-spannungspruefer/spannungspr%C3%BCfer-duspol.html1a) DMMs have their justification for voltages above 240V: In industrial environments, you sometimes have to measure things like working on a 400V 3phase motor. I myself used a DMM to confirm some imbalance on the output of a 80kVA UPS system caused by a improper seated current transformer. And yes, working in CAT IV environment here.
2) Depending on what the task is, Fluke DMM are of high build quality, sure. I would say, that generally you should use good quality equipment and make sure it is suited for the task at hand. Depending on what your requirements are, in some cases even cheap quality chinese DMMs might be used without problems...
3) Regarding electrical safety, I trust the chinese DMMs usually as far as I can throw them, which is not much... Brymen on the other hand has a certain track record of building good quality devices, that are UL marked and also get tested by independent sources like J. Smith here in this forum.
I personally do trust the following brands for mains work: Fluke, Keysight/Agilent, Hioki, Gossen, Brymen. Other brands surely apply, but I have not used them (yet).
That said I would ask another question: Does anyone has reliable data of how well and stable the recent Brymen DMMs are? With Fluke, especially older models, you experience decades-long stability regarding accuracy- my old Fluke 8600 still delivers good readings after 40 years... - Are there any reliable data regarding the stability of Brymen DMMs over, say, 10 years?