FTTH drop cables are often butterfly-shaped, but not all drop cables use this design; the butterfly structure is a common type for indoor and compact installations.

Butterfly-Shaped Drop Cable

A butterfly-shaped optical cable is a type of FTTH drop cable characterized by a flat, compact profile resembling a butterfly in cross-section. The optical fiber unit is positioned in the center, flanked by two parallel strengthening members, which can be non-metallic (FRP or KFRP) or metallic, and the cable is sheathed with LSZH or PE material for indoor or outdoor use . This design provides:

• Small bending radius and superior bend resistance, ideal for tight indoor routing .
• Lightweight and flexible structure, simplifying installation along walls, corners, and conduits .
• Enhanced tensile strength due to the parallel reinforcement members .
• Ease of splicing and connection in terminal boxes or distribution points .

Other Drop Cable Types

Not all drop cables are butterfly-shaped. Traditional drop cables may use a figure-eight structure, with two parallel strengthening cores and a central optical fiber, or a self-supporting design that adds a steel wire for aerial deployment . These designs are more common for outdoor or long-distance installations where mechanical strength and environmental protection are critical.

Applications

• Indoor FTTH networks: Butterfly drop cables are preferred for connecting the fiber access point to the ONT in homes due to their compact size and flexibility .
• Outdoor aerial or duct installations: Self-supporting or armored drop cables are used for longer spans or areas with environmental challenges .
• Residential vs. business access: Single-core butterfly cables are typically used for residential users, while multi-core versions (2–4 cores) can serve business users . In summary, the term "drop cable" includes butterfly-shaped cables as a common type, especially for indoor FTTH applications, but it also encompasses other structural designs depending on installation requirements and environmental conditions .