Report of the Italian inter-laboratories comparison of high dc resistance on the calibration of a 10MΩ and a 1GΩ resistors

A national comparison of high dc resistance at 10MΩ and 1GΩ level was organized by the Electromagnetic Division of National Institute of Metrological Research (INRIM, Italy) and piloted by the high dc resistance Laboratory of the same Division. This comparison took place between January and April 2008 with the participation of 8 Secondary Laboratories accredited by the Italian Service of Accreditation of Calibration Laboratories (SIT). The travelling package included one wire-wound 10MΩ standard and one thick film-type 1GΩ standard in a wooden anti-shock container designed by INRIM. The obtained results indicate that the relative differences at 10MΩ and 1GΩ between each Laboratory's value and the respective reference value are all within the expanded relative uncertainties of these differences at a 2σ confidence level.