A 4 core sm fiber optic cable consists of four individual single-mode optical fibers housed within a single protective sheath. The number of optical cores in an optical fiber is the total number of equipment interfaces multiplied by 2, plus 10% to 20% of the spare quantity, and if the communication mode of the equipment has serial communication and equipment multiplexing, you can reduce the number of cores. The number of. How to Identify Fibers in High-Count Cables (>12 Fibers) For cables with more than 12 strands (e., 48, 96, or 144 fibers), the industry uses a “Tube and Fiber” system. The 12-color sequence is applied twice: first to the outer Buffer Tube, and then to the individual Fiber inside it.