The paper investigates the mid-term results of the tariff regulation influence on the amount of capital expenditures in Russian electricity distribution sector. We estimate panel data with the dynamic investment model using system GMM method. We showed that horizon of tariff regulation period is statistically significant and transition from the short-term regulation to the long-term tariff system had positive effect on the amount of regulated companies’ investments. At the same time we found that the design of long-term regulation applied in Russia in 2009–2013 (type of RAB-regulation and long-term indexation) was not statistically significant to the amount of investments. All over all, the amount of investments in electricity distribution networks has similar to European peers explanatory factors. The obtained results are important to the further improvement of regulation in power energy and can be applied in district heating as well.