Why does my instrument need a calibration?

To ensure that any test instrument is performing to its original specification, it must receive a regular calibration. Test instrument tolerances will change slightly over time and with use. There are a number of reasons for this, and while it is possible to minimise the levels of drift, even in the most modern instruments they cannot be eliminated completely. Therefore, it is necessary to ensure that the test equipment receives its calibration. When an item of test equipment is within its calibration period, it will be guaranteed to produce results that are within its stated specification. Once the calibration period has been exceeded, the results cannot be guaranteed.

What is involved?

Test equipment and instrument calibration is much more than just comparing two instruments to see whether the readings are the same! It requires a full calibration procedure (usually defined by the manufacturer and/or 18th Edition standards). Typically it requires multiple tests across all ranges of all the functions (or main functions). The results of the tests must fall within a specific range to pass. Once the cycle is complete, a Calibration seal is placed on the instrument/meter to show it has not been tampered with since it was proven accurate. You will also be given a certificate of calibration showing the results of the tests, and a sticker is placed on the instrument/meter to show it has a current and valid calibration.