For the optical cables that are routed in to or out from a site, the metal reinforcing ribs should be grounded to the optical distribution frame (ODF) or fiber melt tray in the equipment room. However, this does not mean every fiber optic installation is exempt from grounding requirements. The critical distinction lies in. Protective Earthing is a requirement to divert unwanted, potentially hazardous currents from all exposed metallic parts such as equipment chassis, racks, cabi-nets, cable trays, conduit, and patch panels for personnel safety reasons and to avoid potential damage to equipment. Because low frequency. This Applications Engineering Note (AE Note) discusses conventional bonding and grounding practices for conductive fiber optic cable and hardware installations within the scope of the National Electrical Code (NEC). In North America, the primary source.