The article presents the results of a study of the specific electrical conductivity æ of an equimolar potassium borosilicate melt, which is the basis of a ground enamel for insulating main pipelines. It was found that in the solubility range of nickel oxide (up to 3.0 wt. % NiO) values of æ changed nonmonotonically with increasing NiO content. The introduction of small NiO additives (up to 1.0 wt.%) practically did not affect æ of the melt due to the appearance of microregions enriched with this oxide. The degree of polymerization of formations in contact with K+ ions practically does not change. A decrease in the electrical conductivity of the melt is observed in the range of 1.25-2.00 wt.% NiO due to its polymerization. The experimental data in the ln æ vs T-1 coordinates differ from the linear ones, which is caused by an increase in the mobility of the main charge carriers - K+ ions due to the fragmentation of polymer formations with increasing temperature. A correlation between æ and the activation energy Eæ was revealed. The Eæ value does not depend much on the NiO content, the average Eæ value in the range of 973 -1123 K was 180 kJ/mol. The change in Eæ is due to the addition of nickel oxide, which changes the structure of the melt, and hence the mobility of K+ ions.