Legal requirements for calibrating DMMs

As for the legal part this is difficult because it depends on where you are and what these meters are being used for. It can just as expensive to calibrate in house as sending them out. The standards you need are not cheap. It is really not possible to go into further detail without knowing more of your circumstances. I worked for a world famous test equipment manufacturing concern in the UK and they had a standards lab with six people to calibrate their test gear it cost a large fortune to run.

It had to be air conditioned and have its own separate electrical supply. Only those that worked in there could enter and if you were found using any test gear that was out of date you could be sacked.

hi its mainly for nacoss acreditation.

I would have assumed that the body doing the acreditation would want to know that the person doing the calibrating is of a certain standard to issue a cert other wise what would be the whole point of the exercise

Hello you will need to verify the nacoss requirements. So long as the person carrying out the test procedures can show they have the equipment and that the paperwork proves they know what they are doing. That is a proper schedule is written up showing the nature of the test and the defined accuracy agreed by both parties. You will have to be able to prove all you standards meet the required pass accuracy, they need to be at least 100 times better than the best you want to measure to. Qualifications are not the thing here it is can you show that the test equipment is up to the job. At the end of the day just what are these meters checking? Are they in turn calibrating another item? Do they meet the required accuracy when new? Would it be quicker and cheaper to buy in new meters? Do the testing house you use really do the job asked of them? How would you know? Most basic meters only claim between 1 and 3% accuracy at best. I am sure given all the factors you will come to a conclusion that best meets your needs.

In some places, all that's required is a certificate.

You obtain the certificate by going through training so that you get the fundamentals and methods right.

Before you get your training, however, you have to have a minimum level of education or experience. How much depends, again, on where you are.

When you have a certificate that says that you are a trained calibration technician, you can put your name on the calibration certificate of the device that you calibrated.

The thing with calibrations is that you need to be able to trace the calibration your equipment up to the national level (that is, your country). If you calibrate your DMM, the calibration certificate should state the brand, model and serial number of the calibrator and how accurate it is (must be more accurate than your DMM). The calibrator's calibration certificate needs to say that it was calibrated with another calibrator that is more accurate and belongs to either a regional laboratory or a national laboratory. If it belongs to a regional laboratory, their calibrator's calibration needs to be traced to another, more accurate calibrator at a national laboratory.

When our company went for ISO 9000 certification, we stated that our DMMs were not used to calibrate anything. That meant that they didn't need to have calibration certificates. We still checked their accuracy periodically but we didn't have to document them.

Personally, I would have preferred that we did have calibration certificates for our DMMs but it wasn't our decision.

In the end it all comes down to what are they being used for, who is requesting the calibration certification, and who is going to pay for it.

RS Components (usual disclaimer) do a meter calibration service.

What legal difficulties are being considered, please?

Yes so do plenty of others but at a cost. You have to be UK based. Are the meters worth it. Would buying new be better? The prices keep coming down but calibration costs keep going up. Bulk buying gets a discount.

Like everybody has said, you need to establish the reason for calibration - from which comes an audit trail for the purpose of quality control - thus a calibration check (with a certificate) by an independent person/body is usually taken at face value.

If you do decide that you need to have DMM's calibrated and it's not enough to warrant the cost of the calibration equipment and the manpower to run it, there are calibration labs that will do that task for you.

Most metrology labs I've dealt with in the US will negotiate pricing on different volumes of equipment. If you're here in the US, I can recommend a lab to you.

Fluke is the answer for the most of the cases.

In Europe General requirements for the competence of testing and calibration laboratories You can find in EN ISO/IEC 17025:2000 International Standard

If You want to have accreditation, look at EA-4/02 .issued by European cooperation for Accreditation of Laboratories

You can visit www.european-accreditation.org

But for one unit it is usually not reasonable to do it Yourselves.

If You want to have Your unit carried out with special care, You can specify Your Own Special requirements referring Your unit, in addition to general requirements. And make special agreement with Testing laboratory.

For any case, You can also insure Your Unit.

Yes, FLUKE can do very nice cals, but they tend to be slow. If you don't need a meter repaired, there are several metrology labs that can recertify a meter at a very reasonable cost. They use the same calibrator that Fluke uses; it's one of Fluke's tools. They have to keep them calibrated by Fluke to NTS standards here in the US.

Why pay Fluke more and wait longer?