Calibration documentation

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SparkJ

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I am thinking about buying a Calcard Ext1 to save on the cost of having my Megger recalibrated every year.

But if I get one what documentation do I need to record the results?

I believe that I am supposed to test monthly and note down the results in some sort of log.

And what tolerance am I allowed for the month on month readings before the instrument is deemed to need recalibrating?

 
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First off you need your test standards..

Something to test:-

1) ohms readings

2) IR readings

3) Zs (you can use a nominated socket for this - preferably not RCD protected)

4) RCD operating times (you can use a plug in RCD adaptor for this plugged into the socket you use for your Zs reading)

Each item you use has to have a serial number or be identified specifically

The readings that you should note down are what you can test, I have a box of resistors fitted to banana sockets for my ohms and IR tests; so I note the readings that I get.

When you actually get these readings, what you are after is not accuracy (a 10 ohm resistor might actually be 9.5 ohms), you are after consistency; i.e. the readings that you take from month to month should be the same (or very close). My ohms varies by +/- 0.2 ohms, IR by +/- 1 ohm, Zs by +/- 0.02ohms and RCD readings by <1ms

 

SparkJ

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Thanks for the info. It sounds less daunting than I thought.

 

septiclecky

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One of these cards may be fine for checking that the meter is in tolerances but what do you do if you don't get your meter calibrated every 12 months and when you go to a job and the calibration certs are required but they can not be excepted as they are older than 12 months????

Is it false economy in the long run??

 

paulh

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I was under the impression that you had to have a british standards traceable certificate. Also how do you calibrate your calibrating machine?

I have to get all sorts of equipment calibrated (mechanical and electrical) and as well as being a hassle it all costs money and time. Doing this myself would be an advantage but not sure you can do it easily

 
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You're missing the point of the check boxes. They are there to ensure that you're tester is giving you repeatable results that you can rely upon.

You are not calibrating anything - purely measuring a known source. To calibrate the internal settings of the tester are altered, if required.

If you can satisfy that you had your tester calibrated and then it's still turning out repeatable results , 3 or 4 years later why pay for re-calibration? I thought it wasn't a statutory requirement, merely a suggestion?

 

paulh

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my tester gets calibrated every year....the meter in question has never been altered at the calibration stage because it didn't need it like virtually every single one they test, Every year as the cert runs out one of the companys I work for request the new one. Also this company is quite large with lot's of meter's etc but get them calibrated/checked every year. I haven't researched this but its good practice to check your own meter for repetetive results however a valid test cert will be required. I personally use a 1 ohm resistor and check the same socket every so often.

I think the 3-4 years later approach will not suffice in this cover my a##e society.

I know a collegue of mine had to re-test some ceiling anchors because the cert had expired. When his tester was checked for calibration it was perfect.

 

jl-heating

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niceic are quite happy to accept test results monthly and if the results are within tolerance and can be proved calibration is not req.

straight from the horses mouth ..

in fact i was told not to rely on the yearly calibration and that i had to do monthly verification.

i use 1 of these. CB 200 Full Check Box

 

paulh

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niceic are quite happy to accept test results monthly and if the results are within tolerance and can be proved calibration is not req.straight from the horses mouth ..

in fact i was told not to rely on the yearly calibration and that i had to do monthly verification.

i use 1 of these. CB 200 Full Check Box
I like the sound of thatApplaud Smiley

 

jl-heating

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me to .. i can see me 5 years down the road and no calibration cert but lots of verifications lol..

 

DonkeyDong

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All,

You need to get your meter calibrated, then you use of these CHECK boxes to ensure that the meter does not deviate each month from the previous months reading. The name gives it away - CHECK box. These can not replace calibrating, as you do not know the underlying accuracy.

So basically, get your meter done once a year, and use the check boxes each month to check for variations - this is required by the NICEIC (can't comment on the others).

D.

 
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All,You need to get your meter calibrated, then you use of these CHECK boxes to ensure that the meter does not deviate each month from the previous months reading. The name gives it away - CHECK box. These can not replace calibrating, as you do not know the underlying accuracy.

So basically, get your meter done once a year, and use the check boxes each month to check for variations - this is required by the NICEIC (can't comment on the others).

D.
concur......:DApplaud Smiley

even stupid stuff like a damaged lead or 4mm banana plug could throw out your readings even if meter itself is spot on!

 

septiclecky

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I was under the impression that you had to have a british standards traceable certificate. Also how do you calibrate your calibrating machine?I have to get all sorts of equipment calibrated (mechanical and electrical) and as well as being a hassle it all costs money and time. Doing this myself would be an advantage but not sure you can do it easily
This is why calibration equipment is registered to UKAS system as there are certain places where they can be calibrated and the atmospheric conditions are kept costant to ensurs the readings are correct.

 

paulh

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This is why calibration equipment is registered to UKAS system as there are certain places where they can be calibrated and the atmospheric conditions are kept costant to ensurs the readings are correct.
As I posted earlier "I was under the impression that you had to have a british standards traceable certificate" If someone had posted this earlier(thank's septiclecky) I could of saved my fingers for other thingsGuiness Drink......I knew the reason for the checkboxes but thanks anyway Donkey dong.

 
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