Direct Buried Cable Installation

Direct Buried Cable Installation: Today we will discuss about Direct Buried Cable Installation, why telecom industries do the direct buried cable installation and what process is it? Which type of installation called the direct buried installation? Direct buried means fiber optic cable buried under the ground at required depth specification without any kind of extra protection. Most telecom industries requires underground optical fiber cabling system for its network, This type of project mostly required for the National Long Distance Network. The telecom industries and vendors are least bothered about how this cables routed to the premises and equipment.

One advantage of direct buried cable installation is also that a long project of optical fiber cable laying is completed at a very low cost. In the direct buried cable installation process Steel-tape armor cable install directly under the ground without the use of any protective conduit or duct. Some of the armor cables images mentioned below which used in the Direct Buried Installation.

Type of Armored Cable 

Direct Buried Cable Installation

Trenching for direct buried cable installation

Excavation in any type of soil as indicated, to give the specified depth of cover over installed cable (or additional road crossing duct), including necessary extra depth for a sand bed and extra width and depth for jointing pits where required at jointing locations, together with any shoring, support, dewatering etc. as required (except continuous dewatering by “dewatering system”).

After laying of cables etc., removal of shoring and support, backfilling in layers as specified, including the supply and placement of sand and warning tape/s and, when the excavated material is unsuitable for backfill, the supply of new approved backfill material Clearing site of all excess materials, debris, equipment etc..

Direct Buried Cable details

Example of Direct Buried Cable Installation

Some technical tips you have to remember during the installation of direct buried optical fiber cable-

➥Trench keep clean and must be straight (No sharp bends,no sudden route diversion).
➥Before cable laying make the proper sand bed as per the measurement mention in the company drawing.
➥Fiber optical cable arrange proper and keep in the middle of trench.
➥Sand bed also required on the top of cable after laying.
➥Lay the warning tape at proper depth level.
➥Complete the proper back-filling as per the instruction of guideline Make soil hump on the trench.
➥Material must be used as per the company standard.

The linear measurement shall be from the beginning of trench, to the end of trench, or the end of that type of installation as applicable.The works shall be undertaken in compliance with telecom industry approved Plans, Specifications and Installation Standards and, where applicable, the permits and specifications of the Local Municipality, Ministry of Transport, Ministry of Municipal and Rural Affairs, or other competent roads Authority. Also the regulations and permits of the Traffic Control Authority.

The standard width of the trench used in Telecom Industry

I am not saying that it is the international standard width of the trench but most of the telecom industries uses below mentioned width of the trench

➥CABLE TRENCH, 500 mm. COVER. Standard width 400 mm. For BSW cables installed alone. Trench in foot-way, in urban areas.

➥CABLE TRENCH, 600 mm. COVER. Standard width 400 mm. For all copper cables. Trench in foot-way / roadway in urban areas.

➥CABLE TRENCH, 1000 mm. COVER. Standard width 400 mm. For all copper cables. Trench in roadway in urban areas.

➥CABLE TRENCH, 1200 mm. COVER. Standard width 400 mm. For all optical fiber cables.

➥CABLE TRENCH, 1500 mm. COVER. Standard width 700 mm. For all optical fiber cables.

In different countries of the world, the telecom industries makes its depth and width standard of the trench as per the condition of soil in the country.

Trenching over existing telephone cable route

Precise location of existing cables, preferably by electronic cable locator but including test pits as required. Excavation with due care, including hand digging, to avoid damage to existing cables and to depth to give required depth of cover, together with any shoring, support, dewatering etc. as required (except continuous dewatering by "dewatering system”).

Recovery, or otherwise supply, and reinstall protection board, if existing. After laying of cables etc., removal of shoring and support, back-filling in layers as specified, including the supply and placement of sand and warning tape/s and, when the excavated material is unsuitable for back-fill, the supply of new approved back-fill material. Clearing site of all excess materials, debris, equipment etc.

The standard width of the trench mentioned below-
➥EXISTING ROUTE DEPTH TO 500 mm. Standard width 400 mm.
➥EXISTING ROUTE DEPTH TO 600 mm. Standard width 400 mm
➥EXISTING ROUTE DEPTH > 600 mm- 800 mm. Std. width 400 mm.
➥EXISTING ROUTE DEPTH > 800 mm-1000 mm. Std. width 400 mm.
➥EXISTING ROUTE DEPTH >1000 mm-1200 mm. Std. width 400 mm.

Direct buried cable is also a type of communications or transmissions cable network which is specially designed for the LDN/Junction network . Armored optical fiber cable buried under the ground without any extra covering, sheathing, or piping to protect it.

Direct buried cable specially manufactured to specific tolerances to heat, moisture, conductivity, and soil acidity. It include thin layer of isolation, steel sheath for the protection & insulation and a waterproof outer cover. Direct buried cable also consists of multiple layers of heavy metallic banded sheathing which provide the protection and strength. It also reinforced by heavy rubber covers, shock absorbing gel, wrapped thread-fortified waterproof tape, and stiffened by a heavy metal core.

I have mentioned that dielectric, steel tape or steel wire armored cables very suitable for direct buried. Direct buried cable supplied in the so many varieties for the constructions depending on the severity of the environment in which they are to be installed.

For example- steel tape or steel wire armored cable provides the protection against rodents or any other forms of potential mechanical damage .Armored Cable have the various internal constructions, it has Central Tube, with gel and without gel,Stranded Loose Tube, Flexible and Spiral Space. All cables can be supplied in a wide range of optical fiber types and fiber counts. Any specific requirements can be addressed upon request of telecom industry.