Most accurate Insulation Resistance tester out there?

[davesparks]

they are different types though, if you compare two micrometers there wont be much if any difference betweem them if they have been calibrated

There could be a big difference between them! Being calibrated doesn't affect their accuracy.
One could be accurate to .01mm and one to .001mm for example.
In the same way one ohmmeter could be accurate to .01ohms and one to .001ohms.
They can all be calibrated as many times as you like but one will always be more accurate than the other.

 

[shanky887614]

There could be a big difference between them! Being calibrated doesn't affect their accuracy.
One could be accurate to .01mm and one to .001mm for example.
In the same way one ohmmeter could be accurate to .01ohms and one to .001ohms.
They can all be calibrated as many times as you like but one will always be more accurate than the other.

they have different scales so cant really compare which is more accurate.

this is on the spec sheet when buying

this is the same as you comparing a multimeter and whatever tester you use on 11kv etc

 

[davesparks]

The two ohmmeters could both have the same scales, say 0 - 10 ohms for example.

 

[Silly Sausage]

One could be accurate to .01mm and one to .001mm for example.

We're talking about Resolution there.
Instrument accuracy is a completely different bag of frogs.

 

[Dcf]

I have a megger bmm 500
passes every time on the checkbox( not calibrated as it's not my main test kit any more)
does k ohm and ohms and also tests to 10G ohm on insulation @1000v
had it 12 years
sometimes come up on ebay cheap.
modern equivelant is a MIT 420 I think.

 

[davesparks]

We're talking about Resolution there.
Instrument accuracy is a completely different bag of frogs.

Good point!

But the point that two calibrated instruments could have two different accuracies is still valid.

Let's say one ohmmeter is accurate to 0.05% and one is accurate to 0.01%
Both can be calibrated but will have different accuracies.

 

[Silly Sausage]

Don't forget to account for the 'Digit' error on bottom end readings Dave!
A lower %age accuracy meter is not necessarily better at those low low measurements.

 

[davesparks]

I never said it was, shanky stated that once calibrated all meters have the same accuracy. My point is that this is not correct.

 

[uksparks]

Just read this thread title, I mean flipping heck, why do you need it any more accurate? It's only got to be over 1M ohm strictly speaking, and we are talking of millions of ohms here, it's hardly like we are talking abouts natts whiskers. If my meter tells me a circuit is 100M or 500M I could care less, it's a zillion TOM'S higher than 1M.

 

[Engineer54]

But never the less an option for the OP to ponder.............
Lets not make presumptions on his available budget or technical capabilities..............
That would be rude...................

Yeah, ....for about a micro second!! lol!!

Nothing to do with making OTT presumptions, a typical journeyman electrician, (as well as many small electrical contractors) would not carry such test equipment. Primarily because they wouldn't ever have a need for such test kit....

So when exactly have you, or anyone else ever used a 4 terminal micro ohm Ductor tester, to test a circuits wiring?? It's a totally inappropriate tester, and not what the OP was asking about!!

 

[silver surfer]

Yeah, ....for about a micro second!! lol!!

Nothing to do with making OTT presumptions, a typical journeyman electrician, (as well as many small electrical contractors) would not carry such test equipment. Primarily because they wouldn't ever have a need for such test kit....

So when exactly have you, or anyone else ever used a 4 terminal micro ohm Ductor tester, to test a circuits wiring?? It's a totally inappropriate tester, and not what the OP was asking about!!

as recent as last week actually. Measuring r1r2 on 100 metre runs of 240mm conductors in parallel, 12 cables in total.
the instrument reading was bang on the pre-calculated values as well. Well worth the 40 quid a week hire charge.

i obviously wasn't as entirely clear on the OPs requirements as you were. Didn't realise he was a typical journeyman spark either....

 

[Engineer54]

Really, i thought it was pretty clear what the OP was asking, and it wasn't anything to do with a 4 point Ductor tester!!

So how did you link out those 240mm parallel conductors at one end then??

 

[davesparks]

By twisting then together?

 

[Engineer54]

By twisting then together?

Probably did too!! lol!!

I just can't understand why you would conduct r1 r2 testing on parallel 240mm conductors?? Calculation is more than satisfactory. I certainly wouldn't conduct such tests on what sounds like a main supply, or large sub main....

 

[silver surfer]

Probably did too!! lol!!

I just can't understand why you would conduct r1 r2 testing on parallel 240mm conductors?? Calculation is more than satisfactory. I certainly wouldn't conduct such tests on what sounds like a main supply, or large sub main....

Oh really ? Lol

calculation or presumption ? Seems more in keeping Lol