As I said, in a perfect world, it would be nice that if you connect 1000V to mV input, it should not damage it, and then meter should, in a pleasant voice say: "bip. Dear operator.. please make a note that you connected meter to 1000V on a millivolt range. While I was designed to withstand such overload indefinitely, and your safety is not jeopardized, I am unable to measure voltage correctly. Please change input range to volts. Thank you for your cooperation....bip".
Are you kidding me? ![Face Palm :palm:](https://www.eevblog.com/forum/Smileys/default/xfacepalm.gif.pagespeed.ic.EBDwh1hCfo.png)
Every single one of my DMMs does exactly that, more or less, AFAIK--including some very, very old models. The newer ones with CAT ratings can take that 1000V on any range--ohms, diode check, etc. I believe it is a requirement. As far as there being a requirement for an overload indicator, I'll defer to others since I don't have any written standards to consult. Input protection circuitry is not that hard to make and in any case, is a well known quantity.
Ok, so your point is that it should survive.
Ok, valid point.
And it will, because it was tested it will. Survival is not in question here.
But, if the point is that it should survive, and also show voltage is too high for the range and that there might be dangerous voltages and that you should change range?
On every range
![Popcorn :popcorn:](https://www.eevblog.com/forum/Smileys/default/EatingPopcorn.jpg.pagespeed.ce.yJ6TmC5fSa.jpg)
So here is a brain teaser : in your own words it will survive in any range including Ohms, right. And what will meter set on ohms show when you connect it to say 400V?
It will keep showing Open on the screen. Whoops....
That is exactly why meters for this "I have no clue what to expect" thing do exist. On my BM525 you have auto mode. It will automatically detect AC, DC or Ohms/continuity.
In a single switch position.
You want failsafe?
There are are also Duspol type voltage tester devices. I have BM75EU from that type. Guess what I use when poking around electric installations, power sockets, fuses and anything 240V AC ? It also has vibration warning, RCD tester, and works even when batteries die. LCD with precise measurements and resistance/continuity stops working, but voltage detection still works. That is regulatory requirement for that type of devices.. User safety first. Best accuracy 1.5% DC, 2.5% AC.
BM789 is a electronics meter, very, very nice one. High resolution and accuracy, lots of functions. It even has "fluke like" diode test, continuity with screen blinking, it will remember settings..
It is probably best meter in the class. Even if you don't look at the price.
But it is not failsafe device for field use, it is not explosion proof, it is not IP87...
It requires operator to operate it with intelligence, otherwise garbage in , garbage out.
Don't get me wrong. I do understand that completely failsafe device probably could be made.
You would end up with a device that would be a fancy version of that Duspol type device.
No current measurement. They are inherently unsafe. Slow auto ranging/switching (because now it has to not only range but also decide which one is it supposed to do)...No high bandwidth, for better RF resilience. etc etc..
And no AC mV range.. That is how Fluke solved that problem with F87V.
I prefer to have it, even if it requires thinking when using..
When you guys find perfect meter let me know. I am interested, but in meantime I'll work with what I have.
In a way the instrument designer expects me to do it. That guarantees good results.
Whoever doesn't like that, I have a snarky Open Source zealots like comment : " If you don't like, it make your own!".