The type of patch cord for a fiber optic terminal box depends on fiber mode, connector type, jacket material, and application environment.

Fiber Mode

• Single-mode (SM, OS1/OS2): Best for long-distance connections and low attenuation. Typically used in backbone networks or connections exceeding 500 meters .
• Multimode (MM: OM1/OM2/OM3/OM4/OM5): Suitable for short-distance connections within data centers or LANs, usually under 500 meters. OM1/OM2 are orange, OM3 is aqua, OM4 is violet, and OM5 is lime green .

Connector Type

• LC: Small form factor, duplex, widely used in modern data centers and terminal boxes .
• SC, FC, ST, MPO, MU, MT-RJ, E2000: Other options depending on equipment compatibility and network design .
• Polish Type: UPC (Ultra Physical Contact) for general use; APC (Angled Physical Contact) for low back-reflection applications like FTTH or PON systems .

Jacket Material

• PVC: Standard indoor use, not suitable for air ducts .
• Plenum (OFNP): Fire-resistant, safe for air ducts .
• Riser (OFNR): For vertical shafts between floors .
• LSZH (Low Smoke Zero Halogen): Emits minimal smoke and toxic gas, ideal for high-safety areas or European standards .

Simplex vs Duplex

• Simplex: Single fiber, unidirectional transmission, used for one-way communication .
• Duplex: Two fibers, bidirectional transmission, commonly used in terminal boxes for simultaneous send/receive operations .

Environmental Considerations

• Indoor vs Outdoor: Indoor patch cords are flexible and lightweight; outdoor or indoor/outdoor cords may include UV-resistant jackets or water-blocking features .
• Bend-Insensitive Fiber (G.657A1/A2): Recommended for tight spaces or FTTH applications to prevent signal loss due to sharp bends .

Practical Recommendation

For a typical fiber optic terminal box in an indoor environment:

• Fiber: Single-mode (OS2) for long-distance or multimode (OM3/OM4) for short-distance connections.
• Connector: LC duplex is most common.
• Jacket: PVC for standard indoor, LSZH if fire safety is a concern.
• Mode: Duplex for bidirectional communication. Selecting the correct combination ensures minimal insertion loss, reliable connectivity, and compliance with safety and performance standards .