problem
Most optical-fiber cables have no redundancy contained within. If the cable is accidentally cut or crushed, several, if not all strands may be lost. The client's network could be down until repairs can be made.
solution
When installing optical-fiber cable, pull a 4-pair Category 5e unshielded twisted-pair (UTP) cable along with it. You will reduce pulling tension on the cable, and if the client's optical-fiber backbone cable is damaged, you can plug in the copper cable. This will let you keep the client's backbone running to some extent until repairs can be made.
procedure
David Lacasse is an RCDD and project manager with the telecommunications division of A/Z Corp. in Ledyard, CT.