Zhongtian Optical Cable How can we tell the good from the bad? Let’s analyze this together below.

　　1. Outer Jacket: Indoor optical cables typically use polyvinyl chloride or flame-retardant polyvinyl chloride, which must be smooth, glossy, flexible, and easy to strip. Poor-quality cable jackets lack smoothness and tend to adhere to the aramid fibers inside. For outdoor optical cables, the PE jacket should be made of high-grade black polyethylene; the finished cable jacket should be smooth, glossy, uniformly thick, and free of small air bubbles. In contrast, low-quality cables often use recycled materials for the jacket to cut costs, resulting in a non-smooth surface due to impurities in the raw material and numerous microscopic pits in the jacket. Over time, such defects can lead to cracking and water ingress.

　　2. Zhongtian Optical Cable: Fiber Optics—Reputable cable manufacturers typically use Grade-A fiber cores from major producers, whereas low-priced, substandard cables often employ Grade-C and Grade-D fibers, as well as fibers of unknown origin. Due to their complex sourcing and prolonged transportation, these fibers are frequently exposed to moisture, leading to discoloration; multimode fibers are also commonly mixed with single-mode fibers. However, small-scale manufacturers generally lack the necessary testing equipment to assess fiber quality. Since such fibers cannot be distinguished with the naked eye, common problems encountered during installation include narrow bandwidth and short transmission distances, uneven fiber diameter that makes splicing with pigtails impossible, and insufficient flexibility—fibers that break when bent.

　　3. Reinforced steel wire: produced by reputable manufacturers Zhongtian Optical Cable The steel wire undergoes phosphating treatment, giving it a gray surface. Cables made with this type of wire do not experience increased hydrogen loss, do not rust, and exhibit high strength. In contrast, low-quality optical cables typically use thin iron wire or aluminum wire as a substitute; these can be easily identified by their white appearance and their ability to bend freely when pinched. Optical cables manufactured with such substandard wire suffer significant hydrogen loss, and over time the fiber optic cable ends may rust and eventually break.

　　4. Steel Armor: Reputable manufacturers use longitudinally oriented, band-shaped steel strips coated with anti-rust paint on both sides; in contrast, low-quality optical cables typically employ ordinary iron sheet, which is usually treated for rust resistance on only one side.

　　5. Loose Tube: The loose tube in Zhongtian optical cables shall be made of PBT material, which offers high strength, dimensional stability, and excellent resistance to aging. By contrast, low-quality optical cables typically use PVC for the loose tube; such tubes have a very small outer diameter and will flatten when squeezed by hand, much like a drinking straw.

　　6. Greases: Greases mainly include fiber grease and cable grease. In general, the fiber grease should completely fill the loose tube. Zhongtian Optical Cable The grease shall completely fill every void within the compressed cable core. For fiber-optic grease, the filling level should be no more than half full; for cable grease, it should be applied only to the outer surface of the cable core, with the remaining space in the middle section at both ends left unfilled. If this practice is followed, the optical fibers will not be adequately protected, which can degrade transmission performance metrics such as fiber attenuation and result in poor water-blocking performance that fails to meet national standards. Should accidental water ingress occur, the entire link could be rendered unusable due to water penetration. Under normal circumstances, even if water ingress does happen, only the affected section needs to be repaired—there is no need to replace the entire cable. National standards stipulate that the water-blocking performance must withstand a water column pressure of 1 meter on a 3-meter-long cable for 24 hours without any leakage. Using substandard grease will lead to the same problems, and its poor thixotropic properties may induce microbending losses in the fibers, rendering the overall link’s transmission characteristics non-compliant. Furthermore, if the grease is acidic, it can react with the metallic materials in the cable, releasing hydrogen molecules; exposure of the fibers to hydrogen will cause rapid increases in attenuation, ultimately resulting in complete link failure.