I am installing fiber optic cables between two buildings. Is there a specific # of pull boxes in a underground PVC conduit run? I was told Every 100' there should be a box. I have a copy of the 1996 NEC handbook and could not find anything.
With fiber, you want to reduce the number of times that you have to handle it. Every time you pull it out of a box and loop it to refeed it in, you run additional risk of damage from kinking or other problems. Do a pulling force calculation and make sure that the pulling force required for your pull is less than what is permitted by the manufacturer. As long as the pulling force is within the specs, only place pull points where they are needed for the fiber terminataions. Whenever you use any type of pulling point you have to look at the minimum bending radius permitted for the fiber. In many cases this will require a pull box and not a conduit body. Don(resqcapt19)