An optical fiber cable made entirely of non-metallic components is called All-Dielectric Fiber Optic Cable. Optical fiber cables are designed and manufactured using a combination of metallic and non-metallic raw-materials. Either the cable could be a mix of metallic and non-metallic materials or else it could be purely of non-metallic materials.
Certain applications demand use of only non-metallic materials. If the cables are laid along with electrical cables, or if deployed aerially on a high-tension electrical transmission line, full non-metallic fiber optic cables are preferred. Metallic elements if available in the fiber optic cables may pose threat to the life of staff engaged in installation and maintenance. Also, metallic elements if present in the cable will conduct electricity from the nearest power transmission lines and deteriorate quickly. Even for non-metallic cables, this deterioration is applicable, but the process of deterioration is delayed in case of non-metallic cables.
All-dielectric self-supporting cables are widely deployed overhead on the power transmission towers. Metallic elements are incorporated in the cable to provide armor against external damages by vermin and also to provide mechanical characteristics demanded by extreme deployment conditions. However, if the deployment environment demands non-metallic construction, manufacturers provide All-dielectric fiber optic cables.
The central strength member in an All-dielectric fiber optic cable can be an Reinforced plastic made of glass fibers, Aramid yarns, Glass yarns etc. In contrast, a metallic fiber optic cable’s central strength member could be single or stranded steel wires. If additional strength is required, aramid yarns or glass yarns can be provided on the peripheral layers. There are deployment environments, which demand all-dielectric construction and protection from vermin/rodents. In such cases, non-metallic armoring materials are necessary.
Glass tapes, FRP (Fiber reinforced plastic) rods and or glass yarns can be wrapped over the peripheral layer of the cable to achieve the rodent protection. Studies show that the effect of non-metallic rodent protection methods are inferior to that of metallic protection methods such as steel tape or wire armoring. However, non-metallic cables have superior characteristics such as light weight and protection from electrical surges. All-dielectric fiber optic cables can be deployed near electrical transmission lines without the process of “earthing”.