Optical fiber, as a medium used to transmit data in the integrated cabling system, has the advantages of large transmission rate and long distance, and is increasingly used by people. As we all know, optical fiber is non-conductive and can be protected from inrush currents. Fiber optic cable also has good protection performance, and the metal components in fiber optic cable have high insulation value to the ground, so lightning current is not easy to enter the fiber optic cable, but because fiber optic cable has a reinforced core, especially direct buried fiber optic cable has an armored layer, so when the fiber optic cable line is struck by lightning, it can also happen that the fiber optic cable is burned or damaged. The following are the main measures for lightning protection of fiber optic cable in the construction of integrated cabling projects.
1. For the lightning protection of direct optical cable lines.
①Bureau grounding method, the metal parts in the fiber optic cable in the joint parts should be connected, so that the reinforced core, moisture-proof layer and armored layer of the relay section of the fiber optic cable to maintain a connected state.
② In accordance with the provisions of YDJ14-91, the moisture-proof layer, armored layer and strengthen the core at the joints of the cable should be made electrical disconnection, and are not grounded, the ground is insulated, to avoid the accumulation of induced lightning current in the cable, but also to avoid the difference in impedance between the lightning drainage line and the metal components of the cable to ground circuit and lead to the earth in the lightning current from the grounding device into the cable.
2. For overhead fiber optic cable: overhead hanging line should be electrically connected and grounded every 2km, grounding can be directly grounded or grounded through a suitable surge protection device. So that the suspension line has the protective effect of overhead ground.
3. cable into the terminal box, the terminal box should be grounded, in the lightning current into the metal layer of the cable, the terminal box grounding can quickly release the lightning current, play a protective role. The use of direct buried fiber optic cable has an armored layer and reinforced core, the outer sheath is PE (polyethylene) sheath, can be effective anti-corrosion and anti-rodent bite.
