Cable trench specification | Various type of cable trench

 Hello friends, I had told in my previous blogging that the current carrying capacity of different UG cables.Today I will tell you how the UG cable is laying and how the cable trench is done with the specification.

 

UG cable is very expensive, about 3-4 times expansive and also laying. But due to many reasons we have to do UG Cable. One of them is because of the reason  we have to do UG cable even after being so expensive, is density populated areas where Overhead Network cannot be used. However, the cable should be properly laid because it takes more time to find the fault than the overhead line.

          Before selecting for laying UG cable, the current carrying capacity, voltage drop and short circuit current of the cable are very important factors which I had written earlier in blogging. Generally the life of the cable is 40-50 years. But Incorrect handling/laying can result in insulation damage and decreases the  life of  cable. Therefore, it is necessary that the laying work should be done properly.

    Usually there is some fault which is like this

1) short circuit fault(Fault between two conductor due insulation failure

2) Open circuit fault (due to conductor disconnection

3)Earth fault (fault betwen conductor and earth due to outer sheath insulation failure)

 

Let us tell you about the cable trench, which is mainly of 3 types.

1)Direct laying

2)Draw in System

3)Solid System

 

Direct Laying 

•     1 st a trench to be maid of depth 1 mtr width 500 mm.

•     Then fill fine sand of 75 mm thick.Sand bed required to protect from moisture from ground.
•  Then laid cable again covered with sand of 170 mm thick
•   Then trench covered with Brick/Tiles and Soil.

•     If double cable to be drawn in same trench then spacing between two UG cable is 330 mm to reduce mutual heating effect.ensure that spacing between two cable that fault occuring in one cable does not damage to other adjacent cable.
•        All dimension may be vary as per site condition and approved drawing.

Advantage

•  It is simple and cheaper method than other two.  
•  Generated heat easily dissipated in the ground.

 

Disadvantages

•  Maintenance cost is very high.
•   Difficult to find fault location.
•   If in future due to increase load demand any requirement of new cable installation, then newly excavation to be done as previously which would be more expensive.
•  This method not possible in congested areas such as in metro cities as excavation in that place is so expensive.

 I will tell about the rest of the two processes in my next blog.

Conclusions: Today I tried to write about cable trench. Again I will tell you every design of drawing for erection of UG Cable vary according to location and projects.

Here giving drawing of another project.

If you liked it, please  comments and share.

Also read: 

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