The fiber optic cable represents a wire consisting of one or several glass or plastic threads. It is used for carrying over a signal. The principle action of an fiber optic cable is based on the physical process known as full internal reflection. Its essence consists in reflection of electromagnetic waves from border of two transparent places provided that the wave falls from the place with the big refraction indicator. The fiber optic cable is applied in many areas; however it has received the greatest distribution in construction fiber-optical communication lines. The fiber optic cable is the optimum physical environment for construction structured cable systems. They have more advantages then copper wires: the big pass-band, high degree of noise immunity, in particular, immunity to electromagnetic framing, relative small weight and volume, small attenuation of a light signal, a galvanic outcome of the connected equipment etc.