Steel strand for laying optical cable

Steel strand optical cables are typically installed using aerial messenger strands with lashing techniques, employing careful tension control, proper handling, and adherence to safety and environmental standards.

Messenger Strand and Lashing Wire

Steel messenger strands are composed of six wires wrapped around a central wire, commonly made of carbon steel with a zinc or zinc-aluminum coating for corrosion protection . Lashing wire is usually stainless steel (grades 302, 316, or 430) with diameters between 0.038" and 0.045", selected based on tensile strength and environmental conditions . Proper strand selection ensures long-term durability, especially in coastal or corrosive environments.

Preparation and Planning

Before installation, a detailed survey of the route is essential, including pole or tower spacing, ground clearances, and environmental conditions . Key preparatory steps include:

• Obtaining permits and coordinating with local authorities
• Identifying splice points and slack storage locations
• Ensuring all materials, tools, and personnel are ready
• Planning for safety measures, signaling, and environmental protection

Cable Handling

During installation, the optical fiber cable must be handled carefully to avoid damage:

• Maintain the minimum bend radius at all times
• Avoid twisting or excessive pulling forces
• Use cable lubricants when necessary to reduce friction
• Leave cable reserves in loops or figure-eight shapes for future adjustments

Laying Methods

There are several methods for placing fiber optic cables on steel strands:

1. Drive-off or Moving Reel Method: The cable is raised and lashed to the strand in one continuous operation, suitable for routes accessible by vehicles .
2. Back-pull, Pull-in, or Stationary Reel Method: Used for inaccessible routes; the cable is pulled beneath the strand and temporarily supported by cable blocks .
3. Overlashing: Fiber optic cables are lashed to existing cables on a strand, often used to upgrade or expand networks . Lashing typically begins at the far end of the run, with the lasher moving back toward the fixed reel, ensuring consistent tension and alignment .

Tension and Sag Management

Proper tensioning is critical to maintain ground clearance and prevent cable damage:

• Consider both the strand tension and the loaded cable tension
• Use software tools like SAG10 or PLS-CADD for modeling sag and tension
• Follow manufacturer guidelines for maximum allowable tension

Splicing and Connections

Splice points must be carefully managed:

• Use splice protectors and leave sufficient cable reserves
• Connect fibers using pigtails or direct connectors in distributors
• Ensure unused fibers are properly stored and protected

Safety Considerations

Safety is paramount during aerial installations:

• Use body harnesses, safety straps, and rubber gloves when working on poles or bucket trucks
• Avoid stepping on cables or enclosures
• Be aware of laser light hazards from active fibers

Environmental and Material Considerations

• Polyethylene jackets with carbon black are preferred for UV protection
• Select strand and lashing materials based on environmental exposure and corrosion risk
• Plan for slack storage and cable reserves to accommodate temperature changes and future maintenance By following these methods, steel strand optical cables can be installed efficiently, safely, and with long-term reliability, ensuring optimal performance of aerial fiber optic networks.