Fiber optic pigtails are connected inside the terminal box by splicing them to the incoming optical cable cores and routing them through adapters or splice trays to interface with patch cords or devices.

Pigtail Connection Overview

A fiber optic terminal box serves as the interface between the incoming optical cable and the pigtails that connect to equipment such as optical transceivers or patch panels . The terminal box is designed to terminate the optical cable, protect the fibers, and provide a fixed location for splicing pigtails .

• Incoming fiber cable: The optical cable enters the terminal box through a designated cable inlet. The cable is stripped to expose the fiber cores, typically around 120 cm for indoor installations .
• Pigtail insertion: Each fiber core from the incoming cable is fusion spliced or mechanically spliced to a corresponding pigtail inside the terminal box . The pigtail has a pre-installed connector on one end, while the other end is fused to the cable core.
• Splice tray: The spliced fibers are placed in a splice tray within the terminal box to protect the fusion points and manage excess fiber length .
• Adapter or coupler: The connector end of the pigtail is inserted into a fiber adapter (coupler) mounted in the terminal box. This allows the pigtail to interface with a fiber patch cord or directly with optical equipment .

Routing and Protection

• Fiber routing: Terminal boxes often provide dark-routing or right-routing paths to guide fibers neatly through the box and prevent bending beyond the minimum bend radius .
• Storage: Any excess fiber from the pigtail or incoming cable is coiled and stored in the splice tray to avoid stress on the fibers .
• Fixation: The terminal box structure allows the optical cable to be fixed on one side and the pigtail on the other, ensuring stable connections .

Types of Terminal Boxes

• Straight-through terminal box: Single external hole for receiving the line cable; pigtails are spliced to the incoming fibers and routed to the output adapter.
• Branched-type terminal box: Multiple holes for receiving line cables; supports multiple pigtail connections for multi-core cables .
• Indoor vs. outdoor: Indoor boxes are compact and wall-mounted, while outdoor boxes may have additional protection but are generally not used for pigtail fixation .

Summary

In practice, the pigtail connection location is inside the terminal box, where each fiber core from the incoming cable is spliced to a pigtail, routed through a splice tray, and terminated at an adapter for connection to patch cords or devices. Proper routing, fixation, and protection within the box ensure reliable optical performance and prevent fiber damage .