OPTICAL WAVEGUIDE COVERED POWER CABLE

PURPOSE:To enhance the accuracy of sensing any damage of a power cable by forming an optical waveguide on the outside of an insulated conductor of a power cable through lamination of a plurality of materials having different refractive indices. CONSTITUTION:An optical waveguide path 4 is formed on an insulated conductor 1 prepared by applying an insulating material 3 onto a conductor 2, and outside of the path 4 a plastic sheath 8 is put to form a power cable equipped with a covering film as optical waveguide path. The waveguide path 4 is made by laminating a covering layer 5 of a material having a refractive index n1, covering layer 6 of another material having refractive index n2, and covering layer 7 of the material having the refractive index n1, one over another. The layers 5, 7 of the same index n1 serve as a clad layer while the layer 6 serves as a core layer. Because this causes increase of the optical transmission loss even for a damage of cable in any place, damage sensing can be made accurately. If a boring process is applied to the plastic sheath 8 so that part of the light leaks from the waveguide 4, it can be used to make evacuation of people in case of emergency in a cave road or the like.