Recommended technical requirements are detailed by reference to IEC 60794-3-11 on outdoor optical fibre cables for duct, directly buried, and lashed aerial applications. Panduit does not guarantee any favorable results or assume any liability in connection with this document. In. Direct-burial fiber cable eliminates the need for continuous conduit runs and can be faster and more cost-effective on long, open runs. This article covers cable selection, trench preparation, tracer wire, warning tape, road crossings, and. 1.