Installation of Self-Supporting Butterfly-Shaped Optical Cable Suspension Wire

Self-supporting butterfly-shaped optical cables can be installed outdoors using suspension hardware with proper tensioning, sag management, and adherence to safety standards.

Cable Overview

A butterfly-shaped optical cable features a flat, wing-like cross-section with the optical fiber in the center and parallel strength members on either side. This design minimizes stress when bent in the flat plane and provides mechanical protection against sharp kinks during installation. Outdoor self-supporting variants include a steel messenger wire alongside the FRP strength members, allowing aerial deployment without additional support for spans up to 50 meters. The fiber is typically bend-insensitive single-mode (ITU-T G.657), and the jacket is made of PE or dual-layer LSZH/PE for UV and moisture resistance .

Hardware Requirements

For aerial suspension, the following hardware is commonly used:

• Suspension Clamps: Secure the cable to poles or towers, either via through bolts, bands, or J-hooks for loose tangents. They accommodate a range of cable sizes and installation methods .
• Dead-End Fittings: Anchor the cable at terminal or corner towers, providing strain relief and maintaining grip strength above 95% of the cable's tensile strength .
• Fiber Storage Units (FSU): Store extra cable length along the run for future use or maintenance .
• Wire Suspending Pieces: For self-supporting butterfly cables, these components connect the cable to the suspension hardware and can be removed when transitioning the cable indoors .

Installation Steps

1. Planning and Safety: Ensure personnel are trained, physically fit, and equipped with insulated tools and safety belts. Outdoor work should be avoided in adverse weather conditions such as strong winds, rainstorms, or thick fog .
2. Route Preparation: Identify pole or tower locations, calculate sag and tension based on span length, and ensure compliance with local electrical and safety codes .
3. Hardware Attachment: Install suspension clamps or dead-end fittings at designated points. For long spans, use pre-twisted wire tension clamps to maintain proper tension without stressing the cable .
4. Cable Deployment: Lift the cable using insulated ropes or pulleys, securing it to the suspension hardware. Maintain the flat plane orientation to prevent microbending losses and avoid over-stapling .
5. Sag and Tension Adjustment: Adjust the cable to the recommended sag based on span length, environmental conditions, and IEEE/NESC guidelines .
6. Transition to Indoor Use: At the building entry, remove the suspension wire components to convert the cable into a standard butterfly-shaped indoor drop. Connect to quick-connect or cold splice connectors as required .

Best Practices

• Always respect the flat plane orientation of the butterfly cable to minimize stress on the fiber core.
• Avoid edge-on bending and over-tight fastening, which can cause microbending and long-term signal loss.
• Use saddle clips sized to the cable width for secure attachment.
• Ensure UV and moisture-resistant jackets are used for outdoor sections, and maintain proper separation from power lines to prevent electrical interference . By following these guidelines, self-supporting butterfly-shaped optical cables can be safely and efficiently installed for both outdoor aerial spans and indoor transitions, ensuring long-term performance and reliability.