For grounding metallic components of fiber optic cables, a copper conductor with a cross-sectional area of at least 35 mm² is typically required, with smaller 16 mm² conductors allowed for certain extensions.

Key Guidelines

1. Cable Type Matters Fiber optic cables themselves do not carry electrical current, so fully dielectric cables require no grounding. However, cables with metallic components—such as steel armoring, copper strength members, or metallic messenger wires—must be grounded to prevent electric shock, equipment damage, or fire hazards (Hawell Cable), . 2. Standard Cross-Sectional Areas

• For main grounding connections from the cable to the building's grounding system, a multi-strand copper conductor of at least 35 mm² is recommended (ME Fiber Optic), .
• When extending the grounding from fiber distribution boxes or transfer devices to the existing grounding system, a minimum of 16 mm² copper conductor is acceptable (ME Fiber Optic), .
• NEC Article 770.100 allows a minimum 14 AWG copper wire for grounding, but manufacturers often recommend 6 AWG (≈13.3 mm²) for both bonding and grounding purposes to ensure compliance and low-resistance connections (Corning AEN 140), . 3. Installation Practices
• Grounding conductors should be as short and direct as possible, ideally less than 20 feet, to minimize impedance and maintain continuity (Corning AEN 140), .
• Metallic components should be bonded at each building entry point and termination location to prevent induced voltages from lightning or nearby power lines (Hawell Cable), .
• Use UL-listed bonding clamps and ensure the contact surface is clean and oxide-free for low-resistance connections (Hawell Cable), . 4. Compliance and Verification
• Verify continuity with a low-resistance ohmmeter, ensuring resistance is less than 1 ohm between the metallic component and the grounding system (Hawell Cable), .
• Follow NEC 770.93 for grounding or interrupting non-current-carrying metallic members, especially when cables are exposed to power conductors (SeeClearfield), . Summary For most commercial and industrial fiber optic installations with metallic components, 35 mm² copper conductors are standard for main grounding, while 16 mm² may be used for extensions. Fully dielectric cables do not require grounding. Always follow NEC, NFPA, and manufacturer guidelines to ensure safety and compliance.