NPL precision resistance standards covering the range 10¿4¿109¿

The paper describes the design, method of construction and performance figures of a range of precision wirewound resistance standards that have been made at the National Physical Laboratory over a period of several years. The resistors cover a range of 13 decades; the lowest is a 0.0001 ¿ resistor which will carry a current of 3000A, while the largest is 109¿ and is capable of withstanding a voltage of 10000V. All the resistors are made of quaternary alloys; the methods of annealing these alloys, and of making connections to the various gauges of wire used, are discussed.