The 250μm fibers are positioned in a loose tube made of a high modulus plastic.The tubes are filled with a water-resistant filling compound.A Fiber Reinforced Plastic (FRP)locates in the center of core as a non-metallic strength member.The tubes and possible fillers are stranded around the strength member into a compact and circular core.After the cable core is filled with the filling compound to protect it from water ingress,the cable is sheathed by PE material as inner sheath.After wrapping non-metallic rods(usually FRP),Finally,the cable is sheathed by PE sheath as outer sheath.
