Conductivity of Copper

Expressed as a percentage of the IACS (International Annealed Copper Standard). Small quantities of silver and cadmium have comparatively little effect on conductivity, but 0.05 percent of phosphorus reduces IACS conductivity to about 70 percent; 0.4 percent arsenic reduces it to 40-50 percent and silicon is also particularly harmful. Cold working decreases the con­ductivity of high conductivity copper and when it is in the fully hard-drawn condition, its conductivity is about 3 percent lower than when annealed.