0 feet below natural grade (BNG) will be maintained except that a minimum of 5 feet below natural grade (BNG) will be maintained for fiber optic cable wirelines. Installing, operating and maintaining a fibre network is relatively new to the public sector and there is increasing demand for the sharing of knowledge and. This guide dives deep into the maximum length constraints of the three most common network cables—Ethernet, coaxial, and fiber optic—explaining why these limits exist, how they vary by cable type, and how to extend them when needed. By the end, you'll have the knowledge to choose the right cable. The Fiber Optic Association, Inc. (FOA) was founded in 1995 to help develop the workforce to build the fiber optic networks to support a rapid expansion in communications and the Internet. The charter of the FOA was to promote professionalism in fiber optics through education, certification, and. Establishing minimum height requirements prevents unintentional snagging by tall equipment or vehicles and reduces the risk of injury to individuals carrying long objects like ladders or fishing rods. The lowest minimum clearances for communication lines are designated for areas accessible only to. A minimum depth of 4. FO-VC2 JOINT USE - VERICAL MIDSPAN CLEARANCES 48.