Measurement uncertainty, traceability and evaluation of test results in testing laboratories

The objective of this paper is to elaborate new elements related to metrological analysis in the field of testing, such as measurement uncertainty and traceability. Until now the international standard ISO 45001 did not explicitly require the uncertainty specifications in the area of testing to such an extent as the newly implemented standard ISO/IEC 17025. Therefore several additional steps should be performed in specifying the measurement and testing results, especially concerning performance of testing and other conformity assessment activities. The paper is focused on uncertainty analysis of a test procedure of the electrical safety of household appliances according to the European standard EN 60335-1. The traceability of measurements is presented. The example is chosen as a useful case study, as well as a very illustrative example, where many dilemmas could be highlighted. This particular case is relatively straightforward to evaluate due to the relative ease of traceability of electrical and thermal quantities. It is important that the measurement result and its uncertainty are correctly evaluated and on that basis the right conclusion of conformity or nonconformity with specifications is made. Therefore, knowledge and awareness of all facts about calibration, testing requirements and traceability are essential.