In recent years, the concept of Industry 4.0 and IioT has seen an intensive transition of industrial networks to wired data transmission based on the Ethernet family of technologies. The given chronology of the development of international standards of industrial Ethernet and corresponding cables based on twisted pairs proves the perspective of using a single twisted pair with the possibility of transmitting a power signal, which significantly reduces the number, weight and cost of cables in the network. According to international standards on cables for industrial Ethernet, shielded solutions based on a single shielded twisted pair must ensure the transmission of digital signals in the frequency range of up to 20 MHz over a distance of up to 1 kilometre. The need to use a shielded twisted pair is due to operating conditions under the influence of strong electromagnetic interference. An analytical review of scientific publications shows that shielded cable designs have increased values of electrical capacity. On the basis of numerical modelling of the electric field in the twisted pair, the value of the electrical capacity is determined depending on the design of the screen. It is shown that the shielded twisted pair has significantly larger (by 80 %), electrical capacity values compared to the unshielded one, provided the insulation, screen and protective polymer shell are of the same thickness. The effectiveness of the use of a two-layer aluminium polymer screen is substantiated. It has been proven that varying the thickness and dielectric permeability of the screen film material allows optimizing the cable design to ensure lower values of the working capacity compared to an unshielded pair. On the basis of numerical calculations, it is shown that when the two-layer screen is placed with the film outwards, the working capacity increases significantly and does not differ from the capacity shielded with a solid metal screen. The validity and adequacy of the performed numerical calculations of the electrical capacity of twisted pairs is confirmed by experimental results of measurements of the attenuation coefficient in the frequency range up to 20 MHz of unshielded and shielded twisted pair with a two-layer laminated screen.