We considered a standardized method of determining SEN index of spiral elongation in copper wire. The inconsistencies in the definition of the standards are revealed. Tests of wire in various embodiments of SEN determination are carried out. We propose to verify the compliance with the standards through creation of a preset mechanical stress and to specify the degree of deformation accumulated in the metal. High-temperature copper annealing increases the spiral elongation index and increases its stochastic significance. The stress state that occurs in the experiments is described and its role in the formation of SEN index is analyzed.