Hello
everyone!
Today, I will explain direct-buried optical installations. As I mentioned in the previous article, there are four different types of outdoor cable installations: aerial, underwater, underground in pipes and underground with direct burial.
Now, I will explain the underground way of installing optical cables with direct burial. This method of installation is cheaper and faster than digging trenches, installing pipes and finally installing optical cables. Those were the advantages. Disadvantages of this method of installation: in case of failure there are big problems with repairing the optical cable, after laying the optical cable we no longer have the ability to increase the cable capacity - so you should always provide a higher cable capacity.
Figure 1. Direct-Buried installation
In order to be able to install optical cables in this way, the ground must be suitable, without rocks and stones. Also, it is understood that the municipality or city allows such a way of installing optical cables. There are cities and municipalities where digging and laying a new optical network is not allowed. In these places, there is cable infrastructure and they rent dark fibers or pipes.
The optical cable for direct burial is armored cable. All fiber optic cables must prevent the ingress of water and moisture. In addition, this optical cable has metal elements (wire or plates) to protect the fibers from damage from stones, rocks, rodents and during burial. After installing an optical cable that contains metal elements, such as this optical cable, proper grounding must be provided. In the following figure, we can see this type of optical cable.
Figure 2. Outdoor armored cable
The machine digs and runs the optical cable to a depth of about 1.2 m. The warning tape is placed 300 mm above the optical cable. Manholes and handholes should be provided, where there will be service loops and optical closures. After installing the optical cable, each section must be checked with an OTDR instrument.
After that, the route is marked with identifiable markers, entered in the documentation and GPS coordinates. To prevent damage to the cable: it is installed at the proper depth, a warning tape is placed, identifiable markers are placed on the surface of the land, GPS coordinates are recorded and entered into the documentation.
In the end, as I have already said, after installation, checking the optical cable with OTDR and splicing, it is necessary to ground the cable. Figure 3. shows the grounding procedure.
Figure 3. Procedure of proper grounding
Thank you!
