optic cords and Fiber cables: How to choose and install them for direct underground burial?

When building a high-performance outdoor or underground network, correctly distinguishing and selecting optical patch cords and optical cables is crucial. While both transmit optical signals, only direct-burial-grade optical cables with special protective designs can survive the harsh underground environment for long periods of time, while prefabricated direct-burial patch cords are designed for quick connections.

This article explains the unique structure of direct-buried fiber optic cables, their fundamental differences from ordinary patch cords, and provides industry-standard installation guidelines to ensure your fiber optic communication links are reliable and efficient.

1. 1: he essential difference between optical fiber "Cord" and "Cable"

   
   

In network cabling, "Cord" (jumper) and "Cable" (optical cable) represent different application scenarios and protection levels.

Key takeaway: Optical Cords cannot replace Direct Burial Cables for underground cabling due to their lack of heavy-duty protection. However, in some specialized applications, manufacturers offer pre-terminated Direct Burial Cables for quick connection to outdoor equipment.

2. 2: Structure and key technologies of direct buried optical cables

The reliability of direct buried optical cables (such as GYTA53, GYFTY53 and other models) comes from their multi-layer defense system.

1. Necessary protective layer

• PE outer   sheath : resists erosion by   ultraviolet rays, water vapor and soil chemicals, ensuring that the cable   exterior does not age.

• Armoring : Usually corrugated steel tape (CST), which is the   key layer to resist rodent gnawing and soil pressure.
• Waterproof   barrier : A water-swellable tape or   gel filler that immediately stops moisture penetration along the fiber   bundle if the jacket is compromised.
• Tensile-resistant   elements : Non-metallic   reinforcements (such as FRP rods) or aramid yarns that protect the optical   fiber from being broken during pulling during installation.

2. Fiber Type Selection

3. Installation specifications and depth requirements for direct buried optical cables

Correct installation procedures are key to ensuring the performance of direct buried optical cables.

1. In-depth recommendations (please follow local regulations)

Although optical fiber is used for signal transmission, in specifications such as NEC, the installation depth of outdoor optical cables (OSP) usually refers to the safety standards of power cables to prevent accidental excavation.

2. Key installation steps

1. 1：Utility Locating : Before excavating, you must contact your local service agency and mark all underground pipelines.
2. 2：Bedding   protection : Lay 3-6 inches of sand or soft soil at the bottom of the trench to serve as a cushion for the cables.
3. 3：Laying and pulling :
• The pulling    force must be applied to the cable's strength members , not the optical fiber itself.
• The minimum    bend radius must be strictly adhered    to the manufacturer's requirements, especially at bends and joint closures.
4. 4：Warning and   backfill : When backfilling is halfway done, lay a warning tape with wire . The warning tape should be about 12   inches below the final ground level to allow it to be detected by   detectors in the future.

5 . Frequently Asked Questions (FAQs) About Direct Burial Fiber Patch Cords/Cables

Q1: Can I purchase pre-terminated direct burial fiber optic cables?

A1: Yes. To facilitate quick installation, many suppliers offer pre-terminated direct burial fiber optic cables, often referred to as "direct burial fiber patch cords." These products are factory-installed with connectors (such as LC/SC), but their outer jacket and armor are direct burial-grade. They are primarily used for connecting outdoor equipment over short distances (typically less than 300 meters).

Q2: If I use conduit, do I still need to buy armored direct burial fiber optic cable?

A2: If the conduit (especially metal or thick-walled PVC conduit) provides adequate pressure resistance and rodent protection, it is theoretically possible to use unarmored outdoor fiber optic cable (such as duct cable). However, armored direct-buried fiber optic cable provides greater redundancy and protection and is often used in high-risk environments or where the potential for conduit damage is high. In areas where rodents are active, armoring is still the recommended option, even within conduit.

Q3: Can fiber optic direct burial cables transmit power (PoE)?

A3: Fiber optic cable itself is not conductive and cannot transmit power. If you need to provide both data and power, you need to use a hybrid cable , which encloses the optical fiber and copper conductors (for power) in the same direct burial-grade outer sheath.

Q4: How to connect direct buried optical cables to indoor network equipment?

A4: Direct-buried fiber optic cables must be fusion-spliced with indoor-grade fiber optic cables in a safe location outdoors or near the building (such as a splice box or outdoor distribution box) before entering the building . This is to comply with fire regulations, as the PE jacket of direct-buried fiber optic cables generally does not meet indoor flame retardant requirements.

Q5: After the direct buried optical cable is installed, how to prevent it from being accidentally dug up in the future?

A5: In addition to complying with depth requirements, key preventive measures include:

1. Warning tape : Bury detectable warning tape.
2. Identification   piles : Place eye-catching optical cable identification piles on the ground to mark the direction of the cable.
3. Recording : Accurately record and save cable GPS coordinates   or detailed wiring diagrams.