An installation crew is pulling an optical fiber cable into a riser. The cable has an outside diameter of 25 mm (1 in). As the cable is being pulled off the reel and through a pulley into the riser, you must verify that the minimum bend radius for the cable being pulled is observed. The pulley must be sized at a MINIMUM of:
For optical fiber cables, the minimum bend radius during installation is typically specified as 20 times the cable's outside diameter to avoid damaging the fibers. Given that the cable's diameter is 25 mm (1 in), the minimum bend radius would be 500 mm (20 in). Therefore, the pulley must be sized at a minimum of 635 mm (25 in) to ensure the bend radius requirement is met.
I thought the 10 times the diameter rule still applies.
In the ITSIMM 5-57, states that intrabuilding building cables under stress are at 15 times the OD.
I can’t make any sense out of this