On Tue, 30 Jun 2020 16:09:46 +0100, Ralph Mowery <rmowery28146@earthlink.net> wrote:

> In article <rdecuc$m73$1@reader1.panix.com>, presence@MUNGEpanix.com
> says...
>>
>> > So should I assume the cheaper ones are lying? Or have they just made a rough estimate adding the two errors?
>>
>> might be both. I dug out my first DMM, a Wavetek DM2, circa 1990s. It might
>> have been from a raffle or something like that.
>>
>> The DC voltage specs range from 0.8% +1 digit (not bad really) over to the
>> AC ranges which are "1.2% RDG +10 Digits". If I had new leads, I'd trust it
>> with outlet voltage, but would stay away from 208volts. The meter has 3.5
>> digits or max display of 1999. I'm figuring a real 100volt AC reading could
>> be 99 to 101 plus another error of +/- 1 volt for the 10 digits tolerance
>> on the display or count. so 100volts from your Japanese outlet reference
>> might read 98 to 102 volts. So while in the ballpark, it's better than you
>> can read off a Simpson 260 meter in the AC voltage range. I could be wrong
>> on this too.
>>
>> It's a pretty decent meter for poking at DC circuits for the tens of
>> dollars is must have cost when new.
>
> It seems that maybe due to modern manufactoring the meters are more
> accurate than they were 20 years ago. I bought some DC voltmeters from
> China. They display 3 digits. They read from 0 to 99.9 volts. I coulg
> get 4 of them for less than $ 15 including the shipping. I hooked all 4
> of them in parallel with a Fluke 87 . Three of them tracked right along
> with the Fluke with the last digit sometimes being one high or low from
> 0 to 24 volts. The fourth one was off by an average of 2 on the last
> digit. I found an adjustment screw on the back of the meter and tweaked
> it and re ran the test. It then fell in line with the other meters.
>
> I had 3 or 4 of the Harbor Freight 'free' multimeters. The ones that
> usually sell for around $ 5. They seem to be reasonable accurate for
> the money. Plenty accurate for the home user to test things around the
> house. I do admit that the safety issue of putting them across the 120
> or 240 volt power wires is somewhat doubtful. I sure would not use one
> where I worked to put across the 480 volt 3 phase system that is fused
> with 200 amps.

Whyever not? Even the cheap ones usually state you can use them up to 1000 volts. I've used them on 240 and 415 just fine. I used one on 2000 volts once, and it just failed inside, not even smoke or noise.

In article <op.0nuzmdi9wdg98l@glass>, CFKinsey@military.org.jp says...
> I had 3 or 4 of the Harbor Freight 'free' multimeters. The ones that
> > usually sell for around $ 5. They seem to be reasonable accurate for
> > the money. Plenty accurate for the home user to test things around the
> > house. I do admit that the safety issue of putting them across the 120
> > or 240 volt power wires is somewhat doubtful. I sure would not use one
> > where I worked to put across the 480 volt 3 phase system that is fused
> > with 200 amps.
>
> Whyever not? Even the cheap ones usually state you can use them up to 1000 volts. I've used them on 240 and 415 just fine. I used one on 2000 volts once, and it just failed inside, not even smoke or noise.
>
>

Because I have seen what damage can be done with those circuits.

I have also seen some safty films that the Fluke meter company put out.
Say you take your HF meter and by mistake have it on the ohms or amp
range. Normally an internal fuse would blow. However there is enough
power in the circuits to arc over the fuse, the meter leads instantly
almost explode or look like an arc welder. If you have one hand on each
lead it is possiable the insulation will melt off and maybe into your
hands. You could also become part of the circuit and fry.

Look here around the 6 minuit point.

https://www.youtube.com/watch?v=OEoazQ1zuUM