Changes in the values of the UK national reference standards of electromotive force and resistance-the NAMAS view

The author discusses the changes in the National Physical Laboratory [NPL] reference standard values for electromotive force [EMF] and resistance on 1 January 1990 which will have a significant effect on precise instruments used in industry. This effect will not only be significant at Standards and Calibration Laboratory levels but at shopfloor level where instruments in use have accuracy and stability performances of a few parts per million. Therefore, it is essential that industry is made fully aware of the changes in the values of EMF and resistance