After I asked for additional comments on secure cabling, my friend and colleague Frank Platt sent the following message to the reader who had prompted the discussion. It's bad enough that a rodent may sometimes damage cables, but attackers are also a real threat. It is relatively easy to tap copper cables by getting access to one of many termination points where you can readily clip on, conceal a coupler, hide a transmitter, or punch down your own cable leading to a safe monitoring site. Fiber-optic cables are likely your best security, performance, reliability and value. Copper is fragile electronically and easily compromised intentionally or by mistake.
Fiber cables are inherently very reliable, extensible and secure.
However, my major concern is vandalism of any cable, fiber or copper. A razor blade can inflict major damage, and the chances of being caught are very slim. There are several ways to physically protect cables. Put them inside metal conduit, which most fire codes require anyway. Utilities often pressurize the conduit with a special gel to keep out water and oxygen.