How to Install Direct Bury Fiber Optic Cable

direct bury fiber optic cable is suitable for long-distance communication applications. This blog will show how to install it.
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Table of Contents

1.Avoid crossing or overlapping cable

At first,to ensure proper installation of buried optical cables, it is important to avoid crossing or overlapping cables in the same groove. Instead, pull and lay each cable separately at the same time. This helps prevent any potential damage to the delicate glass fibers that transmit light signals within the cable. To achieve this, follow proper installation procedures and use appropriate tools and equipment to avoid subjecting the cables to excessive tension or stress during installation.

2. Direct bury fiber optic cable requirements

Ensure that the optical cable trench is dug to the required depth and that the bottom of the trench is flat without gravel. If the trench is stony or semi-stony, cover the bottom with a layer of fine soil or sand that is at least 10 cm thick.

  1. Use ground pulleys for mechanical traction to avoid damaging the optical cable.
  2. When lifting and placing the optical cable manually, avoid bending it less than the specified radius of curvature, dragging it on the ground, or pulling it too tightly.
  3. Lay the optical cable flat at the bottom of the trench and avoid leaving it loose or arched.
  4. Follow the design requirements for optical cable laying and treatment.
  5. Check the outer skin of the optical cable for damage during or after laying, and repair it immediately if necessary. After burying the optical cable, test the insulation resistance of the optical cable sheath to the ground.
  6. Before backfilling the trench, check and confirm that the optical fibers and copper wires in the optical cable meet the quality acceptance standards.

3.Tips of Backfill Soil

To ensure proper burial of the optical cable, the backfill soil in the trench should meet the following requirements:


First, backfill the trench with a 15 cm thick layer of broken soil or fine soil, and avoid pushing stones, bricks, frozen soil, or other debris into the trench. The backfill should be leveled manually to avoid any damage to the optical cable.

The backfill should be at least 10 cm above the ground level to provide adequate protection for the optical cable.

4. Proper anti-jamming measures

To ensure proper anti-jamming measures for buried optical cables, the following requirements should be met in accordance with the design regulations:

  1. For optical cable lines passing through railway and road crossings without excavation, the pipe jacking method should be used, with the steel pipe meeting the design requirements and positioned correctly. The ground can be protected by pipes, pipe jacking, or buried protection, with the pipe orifice blocked.
  2. Optical cable lines crossing mechanized roads, rural roads, urban areas, residential areas, or unstable ground should be constructed according to the design’s required protection method.
  3. When laying red bricks on top of the optical cable, first cover it with 20 cm of crushed soil, then lay the red bricks vertically.
    When optical cable lines pass through trenches, canals, or ponds, the top of the cable should be protected with cement boards or cement sandbags.
  4. Slope protection should be used for optical cables passing through ditches and terraces higher than 0.8 meters, following the design requirements. For ditches below 0.8 meters, slope protection is generally not required but must be rammed and restored to the original state.
  5. Optical cable lines passing through termite activity areas should be treated with termite prevention according to regulations.
  6. Lightning protection measures for optical cable lines must follow the design regulations. When using lightning protection drainage lines, lay them 30 cm above the optical cables, with single or double drainage lines. When optical cables are dug out after backfilling and relaying, strictly check for any inversion of the drainage lines above the optical cables.

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