This is because apart from one-core optical fiber, there are basically no optical cables with an odd number of cores, such as three-core, five-core, etc. It is worth noting while one optical core can connect to multiple terminal devices in a series. Made from either high-quality glass or plastic, the core plays a critical role in determining the cable's performance. The total number of cores for a 1pc fiber patch cable is calculated as the number of. According to the IBDN standard, we generally recommend using 12 cores for the communication room in each building, and 24 cores for the building room. Number of wiring points and switches.