Fiber optic cables are at the core of modern telecommunications, providing fast, reliable data transmission over long distances. For many businesses and organizations, running fiber optic cable underground is a preferred method to ensure durability, security, and minimal interference. In this guide, we’ll walk you through the process of running underground fiber optic cables while highlighting the important steps, tools, and considerations.
Choosing the Right Fiber Optic Cable
The first step in running fiber optic cable underground is selecting the appropriate type of cable. The most commonly used cables for underground installations are those with a durable outer jacket, which is resistant to moisture, temperature changes, and physical damage. For longer distances, single mode fiber is often preferred due to its ability to transmit data over greater distances with minimal signal loss. In contrast, multimode fiber is more suitable for shorter distances but offers the advantage of being more cost-effective.
Mapping the Route
Planning the path for your underground fiber optic installation is crucial. The cable should be laid along the most direct and efficient route, avoiding obstacles such as trees, roads, and existing utilities. In some cases, optical ground wire (OPGW) or fiber optic ground wire can be used to offer both grounding and fiber communication, providing a dual-purpose solution for installation in areas with high electrical interference.
Legal and Safety Considerations
Before digging, it’s essential to ensure that you have obtained any necessary permits and are in compliance with local regulations. Most locations have specific rules for cable depth (typically 18-24 inches) and requirements for safety during the installation process. Make sure you identify and mark the locations of any existing utilities to avoid damaging them during the installation.
Fiber Optic Cable
Selecting the right fiber optic cable is vital to ensure the longevity and performance of your installation. For underground use, consider using all-dielectric self-supporting cables, which are lightweight yet robust and do not require metallic components, making them resistant to corrosion. In addition, cables with a protective outer layer, such as aluminum clad steel wire, provide enhanced strength and protection against external environmental factors.
Conduit and Protection
Underground fiber optic cables require protection against physical damage and moisture. To achieve this, you will need to install conduit along the trench. PVC or HDPE conduit is commonly used for underground applications, ensuring that the fiber optic cable remains safe from external threats. Always ensure that the conduit is securely sealed at the ends to prevent dirt and moisture from infiltrating the system.
Digging Tools and Equipment
You can either dig the trench manually with a shovel or use a trencher for faster, more efficient digging. For more precise installations in areas where digging may cause disruption, horizontal directional drilling (HDD) can be used to create a tunnel for the cable, minimizing the surface disruption.
Step 1: Digging the Trench
The trench should be dug to the appropriate depth, usually around 18 to 24 inches, depending on local regulations. Make sure the trench is wide enough to accommodate the conduit and allow for easy access to the cable if future maintenance or repairs are required. The trench should also be free of sharp objects or debris that could damage the cable.
Step 2: Laying the Conduit
Once the trench is ready, place the conduit carefully to protect the fiber optic cable. The conduit acts as a shield against physical damage and environmental threats. When placing the conduit, avoid sharp bends, as this could damage the cable or impair its signal transmission. For enhanced protection, consider using fiber optic break out cables, which allow for individual fiber strands to be easily accessed and terminated.
Step 3: Pulling the Fiber Optic Cable
When the conduit is in place, it's time to pull the fiber optic cable through. This can be done using a cable reel, cable puller, or fish tape. Be cautious not to apply excessive tension to the cable, as this can lead to damage. If you're using a fiber patch cord, make sure it is the appropriate length and rated for outdoor use. For large-scale installations, a MPO patch cord might be necessary for connecting multiple fibers simultaneously.
Fiber Optic Splicing and Termination
Once the cable is pulled through, the next step is splicing and terminating the fiber optic cable. This can be done using a fusion splicer, which uses heat to fuse the ends of the fiber, ensuring a strong, low-loss connection. After splicing, connectors should be attached to the fiber ends for easy installation into networking equipment. If needed, a fiber optic splitter can be used to distribute the signal to multiple locations.
Testing the Installation
After termination, it’s crucial to test the fiber optic cable to ensure it is transmitting data correctly. An OTDR (Optical Time Domain Reflectometer) can be used to measure the integrity of the fiber, checking for signal loss or breaks. Testing ensures that the installation is functioning optimally and that there are no issues that could impact performance.
Backfilling the Trench
Once the cable is tested and working, backfill the trench carefully, ensuring that the conduit and fiber optic cable are not disturbed during the process. The backfill should be done in layers to avoid pressure on the cable. Always ensure the cable remains safe and undisturbed by heavy machinery or traffic above ground.
Final Inspections and Documentation
Finally, conduct a thorough inspection of the installation and document the cable's route, depth, and any connections made. This documentation is helpful for future maintenance or troubleshooting and ensures compliance with local regulations.
Running fiber optic cable underground is an effective and secure way to establish reliable connections in your network. By following these steps and using the right materials, such as fiber optic ground wire and anchor clamps for support, you can ensure a durable and efficient installation. For all your underground fiber optic cable needs, SDGI offers a wide range of products, including fiber patch cords, drop cables, and multimedia boxes, all designed for high performance and longevity.
For more information or to view our products, visit SDGI.
