Electrically conductive yarns are able to provide both electrical/electronic and high-quality textile characteristics in the smart textiles with a high level of artificial intelligence and a high degree of electronic component integration in the textile structure. It is feasible to incorporate them into the fabrics by weaving, sewing or knitting. Depending on the connection type in the electric circuit, conductive yarns can form conductive traces or sheaves, which are composed of separated conductors. In the research the following materials are usually used: metal wires and cables, non-metallic carbon fiber textile yarns and filamentary constructions with metal particles, which may be divided into the twisted yarns, multi-filamentary and galvanic coated multi-filamentary yarns. The paper explains such concepts as smart textile with integrated electronic/electrical systems, conductive yarns and textile switch, as well as replacement alternatives for wires in the smart textiles and their methods. The experiments with different conductive yarns are analyzed in order to determine the suitability for integration into the fabrics the components of electrical systems: for example, the silver coated yarns have a higher electrical resistance coefficient of variation and a different electrical resistance under the strained and free condition. The manufacturing technologies of the electrically conductive yarns and the used materials have a significant impact on the properties of electrical resistance. The integration options of conductive yarns in such an electrical system element as switch are also discussed.