Fiber optic cable installation isn't always about digging trenches. While burying is common for durability, aerial deployment and even indoor use are viable, offering flexibility based on your specific needs and environment. And while overhead laying needs a lot of poles for installation, but the aerial fiber optic cable is cheaper than the direct burial fiber optic cable. Direct Burial Direct burial refers to the laying method of burying optical cables directly in the underground soil. Usually, in ordinary soil and hard soil. A1: Underground fiber optic cables are typically buried 18–36 inches, depending on local regulations, soil type, and site conditions. Typically, in regular or hard soil.