Requirements for laying overhead optical fiber cable strands

Overhead optical fiber cables require proper pole spacing, cable type selection, tensioning, grounding, and environmental protection to ensure reliable aerial deployment.

Cable Types and Support

Overhead fiber optic cables are generally installed as self-supporting (ADSS) or messenger-supported. Self-supporting cables carry their own weight and are suitable for long spans, while messenger-supported cables rely on a steel strand for mechanical support. Both types typically use galvanized steel strands (e.g., 7/2.2mm for suspension) to provide tensile strength and resist environmental stresses like wind, ice, and temperature fluctuations .

Pole Spacing and Height

• Urban areas: 25–40 meters between poles, typically 10–12 meters high.
• Suburban/rural areas: 40–50 meters spacing, 12–15 meters high.
• Maximum spacing in other sections should not exceed 67 meters . Poles must be installed according to design requirements, with concrete or wooden footings as appropriate.

Tensioning and Sag

Cables must be tensioned to 15–20% of their breaking strength during installation. Sag should account for elongation under maximum load and environmental conditions. Hooks or clamps should be spaced approximately 50 cm apart, with an allowable deviation of ±3 cm . Proper tensioning prevents microbending losses and ensures long-term reliability.

Clearance and Safety

• Low voltage (<1 kV): 1.2 m vertical clearance
• Medium voltage (1–33 kV): 2.5 m
• High voltage (33 kV): 3.5 m with arc protection for ADSS cables Grounding is essential for ADSS cables, typically using copper grounding wires every 500 meters, lightning arresters on end poles, and grounding rods (2.5 m length, 16 mm diameter).

Environmental and Mechanical Considerations

Cables must withstand temperature ranges from -40°C to +80°C, wind, ice, and other environmental stresses. Bend radius should be at least 20 times the cable diameter to prevent microbending loss. Light-armored cables may use slightly smaller steel strands (7/2.0mm or 7/1.8mm) depending on mechanical requirements .

Installation Workflow

1. Route Survey: Use LiDAR or other mapping tools to identify obstacles and terrain variations.
2. Cable Selection: Choose ADSS or messenger-supported cables based on span length and capacity requirements.
3. Pole Setting: Install poles with proper depth and footings.
4. Tensioning and Lashing: Apply correct tension and secure cables with lashing or self-lashing methods.
5. Termination and Testing: Strip cable jackets, splice fibers in IP65-rated enclosures, and test insertion loss (<0.1 dB per splice), . Following these requirements ensures reliable, durable, and safe overhead fiber optic cable installations suitable for urban, suburban, and rural environments.