Professional Answer: The longevity of underground fiber optic cables is determined by the quality of the cable and the installation method. To ensure long-term performance, it is best to use armored direct burial cables or, even better, install cables within protective conduits. This safeguards against soil pressure, moisture, and rodent damage. Additionally, proper planning, including locating existing utilities and burying the cable at a sufficient depth below the frost line, is essential. Our company supplies a full range of underground cable laying equipment and tools to help you create durable and secure installations.