What are the common types of butterfly-shaped drop cables

Butterfly-shaped drop cables are widely used in FTTH and access networks due to their compact, bend-resistant design and ease of installation.Structure and Types

Butterfly-shaped drop cables are named for their figure-eight or butterfly-like cross-section, featuring a central optical fiber with parallel strengthening elements on either side. These strengthening elements can be metallic (steel wires) or non-metallic (FRP rods) depending on the application . Common types include:

• Single-core butterfly cables: Typically used for residential access, providing a simple and cost-effective solution .
• Multi-core butterfly cables (2–4 cores): Designed for business or higher-capacity connections .
• Self-supporting butterfly cables: Include an additional steel wire or rope for overhead installations, allowing spans up to 50 meters .
• Armored butterfly cables: Feature aluminum armor and water-blocking tape for harsh environments or duct installations .

Applications

• Indoor use: Lightweight, flexible, and suitable for wall-mounted or pipe-laid installations. Indoor versions are generally less expensive than outdoor types .
• Outdoor use: Can be used for short-distance pipe laying or aerial lead-ins. Self-supporting versions are ideal for overhead connections from poles to buildings .
• Residential buildings: Often installed using corrugated pipes or floor crossing boxes to protect the cable and maintain proper bending radius .

Advantages

• Small bending radius: Can bend as tightly as 20–30 mm without damage .
• Lightweight and easy to fix: Simplifies installation in tight spaces.
• High tensile strength: Can withstand side pressure, dragging forces, and occasional stepping during construction .
• Easy termination: Compatible with various quick connectors and fiber distribution boxes .

Installation Considerations

• Avoid prolonged water immersion; not suitable for direct underground laying .
• Maintain minimum bending radius: ≥30 mm during installation, ≥15 mm after fixing .
• Traction should not exceed 80% of allowable tension; instantaneous maximum traction ≤100% .
• Use cable reels and trays to prevent entanglement during deployment .

Splicing and Termination

• Fusion splicing: Provides low-loss, permanent connections by welding fiber ends with heat .
• Mechanical splicing: Uses connectors to align and secure fiber ends without heat, suitable for temporary or emergency connections .
• Cold splicing: Quick method for emergency repairs, connecting fibers with a flange head . Butterfly-shaped drop cables are therefore a versatile and reliable choice for both indoor and outdoor fiber optic deployments, offering durability, flexibility, and ease of installation for residential and business networks .