Fiber Optic Splice Box Construction

Fiber optic splice boxes are assembled by preparing the cables, organizing fibers in splice trays, performing fusion or mechanical splicing, and sealing the enclosure to protect the connections.

Fiber Preparation

The first step involves removing the outer jacket of the fiber optic cable and any shielding or armor to expose the loose tubes. A length of about 3 meters is typically left for handling and splicing. The fibers are then cleaned and abraded to remove excess filling material and ensure a smooth surface for sealing and splicing.

Strength members are also exposed and prepared for grounding if required. Cable Installation in the Splice BoxThe prepared cable is inserted into the splice box entry port, often using sealing rings that match the cable diameter. The cable is secured with clamps or tape to prevent movement, and grounding is applied to the shield layer if present.

Proper routing ensures that fibers are not bent beyond their minimum bend radius, which could cause signal loss.

Splice Tray and Fiber Organization

Inside the splice box, splice trays or cassettes hold the fibers in an organized manner. Each tray contains splice holders and fiber guides to maintain orderly routing and prevent stress on the fibers. This organization is crucial for maintenance and future network expansion.

Splicing Methods

Two main splicing techniques are used: Fusion Splicing: Fibers are precisely aligned and fused using an electric arc, creating a permanent, low-loss connection with attenuation typically below 0. 1 dB. This method is preferred for high-performance and long-haul networks.

Mechanical Splicing: Fibers are aligned in a precision device with index-matching gel, allowing light to pass through with slightly higher loss (around 0. 3 dB). This method is faster and can be used for temporary or field repairs.

Sealing and Protection

After splicing, the trays are placed inside the robust housing of the splice box. The enclosure is sealed to protect against moisture, dust, and mechanical stress. Compressed-gel seals or adhesive tapes are commonly used to ensure environmental protection.

The box may also include strain reliefs to prevent tension on the fibers.

Final Checks

Once assembled, the splice box is inspected to ensure fiber routing is correct, splices are secure, and the enclosure is properly sealed. This ensures minimal signal loss, high reliability, and ease of maintenance for the fiber optic network. By following these steps, fiber optic splice boxes provide a durable, organized, and low-loss solution for connecting multiple fiber cables in both indoor and outdoor installations.