Behavior of resistors and shunts: with today´s high-precision measurement capability and a century of materials experience, what can go wrong?

The characteristics of laboratory resistors and high-precision resistors in the principal range, 1 Ω to 10 kΩ, are reviewed. Also reviewed is the history of the shunt and of shunt construction. A method is given for improving the uncertainty of shunts by a factor of five by measuring temperature and providing the resistance-temperature characteristic. Data for high-current shunts using this method are included showing the improvement even in cases where shunt behavior is less than expected. Data are also given for the uncertainty improvement achieved with a common meter type, high-current shunt. The results of efforts to identify the cause of the behavior that went wrong in high-precision shunts are also presented