Accuracy of test instrument

[lofty84]

state three methods for checking the accuracy of test equiptment.

calibration
check box
check against someone elses meter

can you think of anymore ?

If an instrument is found to be inacurate after tests have been completed list three ations which should be taken

what would be your standard procedure for this ?

 

[tony mc]

I would re check the meter and make sure the batterys are in good order. (Could be that simple especially if its a1552) as per manufacturers instructions.

Check the meter against another meter to see if the readings differ or check box / both.

Have the meter re calibrated repaired if still not accurate.

You would need to re test the previous things to make sure everything is in order.

You would normally have a rough idea of what the test results are giong to be so alarm bells should be ringing quickly.

 

[Martin Bradley]

known resistor values. like my little box, home made lol
make your own check box

 

[lofty84]

nice gadget Bradzz

what about send it of for calibration and re do tests, let people know about suspect results, let client know also

 

[Knobhead]

The last time I sent a Fluke to Dowding & Mills the company I worked for complained it would have been cheaper to buy a new one. D&M is where the company all sent all the instruments off the plant. Can’t do right for doing

 

[Martin Bradley]

its accuracy was checked against calibrated equipment, its a just incase you drop your tester box, then you can check it against a bench mark, and previous tests, do you realy know how often your tester should be checked?
look it up and you might be suprised.
and yes i do have all my equipment calibrated, onsite calibration, are a good company.
but you was asking about diff methods and mine is one.
and dont forget a resistance value of 1 ohm will still be 1 ohm the next day ?
Lofty,check out IQ post, sounds good to me.
just because i made my own little resistance check box dont mean it aint any good, or would you rather pay someone to make you one. the NICEIC like that i had one even though it was a home made one, as not many sparks have a check box.

 

[IQ Electrical]

Guys, this whole calibration thing is so misunderstood, not just by electricians but assessors too!

The problem is that a calibration company will calibrate your thermos flask if you ask them to, no mention will be made of any requirements to calibrate or not!

Have a read of this : http://www.esc.org.uk/fileadmin/user_upload/documents/industry/best_practice/BPG7_10.pdf

 

[Golden_Boy]

nice gadget Bradzz

what about send it of for calibration and re do tests, let people know about suspect results, let client know also

When test equipment is "tested for accuracy" its not "Calibrated" at all ? So why call it "calibration". Does anyone know exactly how modern testers are calibrated? I would assume a firmware tweek would be involved as there would appear to be nothing to physically adjust ( at least not in the stuff i've seen inside of?? Its one of these areas that makes me go MMMMMMM....

 

[IQ Electrical]

When test equipment is "tested for accuracy" its not "Calibrated" at all ? So why call it "calibration". Does anyone know exactly how modern testers are calibrated? I would assume a firmware tweek would be involved as there would appear to be nothing to physically adjust ( at least not in the stuff i've seen inside of?? Its one of these areas that makes me go MMMMMMM....

Exactly my point.

 

[Golden_Boy]

Exactly my point.

I have asked this question several times and have yet to receive a satisfactory answer.
It wouls appear that " we will check your kit against ours and tell you how good/bad it is" sounds a lot less technical than "Calibration"

 

[IQ Electrical]

Snake oil.

 

[Golden_Boy]

Snake oil.

And LOTS of it......... ( unless someone knows diffrent )

 

[Martin Bradley]

No it works for me stops my boots squeaking. lol

 

[Golden_Boy]

When test equipment is "tested for accuracy" its not "Calibrated" at all ? So why call it "calibration". Does anyone know exactly how modern testers are calibrated? I would assume a firmware tweek would be involved as there would appear to be nothing to physically adjust ( at least not in the stuff i've seen inside of?? Its one of these areas that makes me go MMMMMMM....

No takers then????????????
Come on all you "calibration" folk ... defend yourselves..............
Dont worry about being technical.. we can take it...

 

[UNG]

and dont forget a resistance value of 1 ohm will still be 1 ohm the next day ?

Depends on the ambient temperature on both days as resistance varies with temperature. That is why you may get inconsistent readings when taking your meter from a cold van into a warm building as the meter acclimatises to the ambient temperature the test results will vary until the meter reaches ambient temperature

just because i made my own little resistance check box dont mean it aint any good, or would you rather pay someone to make you one. the NICEIC like that i had one even though it was a home made one, as not many sparks have a check box.

I just use a collection of resistors why pay £'s for a fancy box when pennies will buy you a handful of resistors that will do the same job

 

[Golden_Boy]

I just use a collection of resistors why pay £'s for a fancy box when pennies will buy you a handful of resistors that will do the same job

My sentiments exactly........

 

[Martin Bradley]

It cost me a total of £5 cheap as chips. And the resisters wont get lost. or damaged, so what is the diff between, having and inclosure and not,
Better than sitting down doing nowt.
And im glad my home made box looks fancy, as it impressed the NICEIC.

 

[Golden_Boy]

I'm still waiting for an explanation of " calibration" ????
If I dont get a reply I will assume its one great big CON.

 

[UNG]

I'm still waiting for an explanation of " calibration" ????
If I dont get a reply I will assume its one great big CON.

How have you got this far without understanding calibration and the need for it. Every time you null (zero) your meter for an r1 r2 test you are carrying out a form of calibration. It may help you understand calibration if you read this

Calibration - Wikipedia, the free encyclopedia

In a nutshell your meter is compared with a known standard source when your meter is checked (calibrated) against this you should receive a list detailing it's readings / accuracy on all it's ranges and functions

If it is a great big con then there are a lot of gullible people out there who have been ripped of for many years, I don't think it could have gone on for this long if it was or are you blowing the lid on it

 

[Golden_Boy]

Quoting from that document
"
In general use, calibration is often regarded as including the process of adjusting the output or indication on a measurement instrument to agree with value of the applied standard, within a specified accuracy. However, very few instruments can be adjusted to exactly match the standards they are compared to. For the vast majority of calibrations, the calibration process is actually the comparison of an unknown to a known and recording the results."

I always understood Calibration to require some sort of adjustment but not in this case, only a report stating the accuracy is needed? So in my understanding of the english language its not "calibration" at all, Merly the production of a report telling the owner how good ( or indeed BAD ) the kit is!