How to connect a fiber optic splice box underground

Installing an underground fiber optic splice box involves careful cable preparation, precise splicing, secure sealing, and proper placement to ensure long-term network reliability.

Tools and Materials Needed

• Fiber optic splice closure (dome or inline type) suitable for underground use ( )
• Fiber cleaver and fusion splicer
• Heat shrink sleeves or mechanical protection
• Sealing tape and gaskets
• Cleaning supplies (alcohol wipes, lint-free cloths)
• Cable clamps or hose clamps
• Optional: desiccant packs for moisture control ( )

Step 1: Cable Preparation

1. Remove the outer jacket of the fiber optic cable, including any armor or shielding, to expose the loose tubes ( ).
2. Leave approximately 3 meters of cable for preparation and splicing.
3. Clean the exposed fibers and strength members using a cleaning solution.
4. Abrade the outer cable jacket for about 150 mm to ensure proper sealing and adhesion of the closure components ( ).

Step 2: Installing the Cable in the Splice Closure

1. Select sealing rings that match the cable diameter and place them on the cable.
2. Insert the cable into the designated entry port of the splice closure.
3. Connect and ground the cable's shield layer if applicable.
4. Wrap self-adhesive sealing tape between the sealing rings to create a watertight seal.
5. Secure the cable to the base of the closure using a hose clamp or provided clamp, ensuring stability ( ).

Step 3: Fiber Splicing

1. Separate the fiber cores and prepare them for splicing.
2. Use a fusion splicer to join fibers, ensuring minimal signal loss.
3. Place spliced fibers into splice trays for organized management.
4. Apply heat shrink tubing or mechanical protection to reinforce the spliced areas ( ).

Step 4: Sealing and Closing the Splice Box

1. Ensure all entry points are properly sealed with gaskets or heat-shrink tubing to prevent moisture ingress.
2. Insert desiccant packs if recommended to control internal humidity ( ).
3. Assemble the closure housing and verify that it is securely fastened.
4. Confirm that the closure is properly supported and positioned for underground installation ( ).

Step 5: Testing and Verification

1. Test the spliced fibers using an Optical Time-Domain Reflectometer (OTDR) or other appropriate testing equipment.
2. Measure insertion loss and return loss to ensure the splice meets performance specifications.
3. Address any detected faults before backfilling the trench ( ).

Step 6: Final Installation

1. Place the splice closure in its designated underground location, such as a handhole or direct burial trench.
2. Backfill the trench carefully, avoiding large rocks or debris that could damage the closure.
3. Place marker tape or warning signs above the buried splice box to prevent accidental damage during future excavation ( ).

Maintenance Tips

• Periodically inspect the splice closure for water ingress, physical damage, or fiber strain.
• Ensure that all seals remain intact and that the closure remains stable in its underground location ( ). By following these steps, you can ensure a secure, organized, and long-lasting underground fiber optic splice installation that maintains network performance and simplifies future maintenance.