session-4 (optical fiber laying)

7/29/2019 Session-4 (Optical Fiber Laying)

1/11

Optical Fiber Laying Procedures

Laying means installation on supervision basis for

successful project completion. Cable ends should be sealed.

Exposed cables should be protect from public traffic.

Cable should not be more pull by the manufacturer

recommendation. Cable bend should not be reduced from the manufacturer

recommendation.

The minimum bend formula r = 20*diameter of OFC.

Loading, unloading and moving of OFC shall be properly.

Cable drum shall always be carry on their flanges.

Use of nails shall be avoided on drums of cable because ofvarying flange thickness.


2/11

Preparation for Excavation of trench

Strictly follow the route plane.

Local authority shall be informed.

All the required materials shall be on site.

Diversion of traffic shall be organized where necessary.

A line shall be marked on the ground with a string ormarking compound.

The trench shall be in-side from the extreme edge of rightof way (row).


3/11

Excavation of trench in normal soil

In normal soil, the trench shall be Excavated to a depth of

1.5 meter. The width of trench shall be 40 cm at the top and 35-40 cm

at the bed.

The depth reference for the trench shall be taken from theroad surface,

The bed of sand 10 cm deep shall be laid along the bottomof the trench and above the cable.

Bricks shall be placed on the cable with no space betweenthe bricks.

Double layer of bricks shall be used in less populated ruralareas.

The optical fiber warning tape is used at 75 cm frombottom of the trench and then back filling with samematerial.


4/11

Excavation of trench in Sandy area

The trench depth and width should be same as for normalsize.

If the bottom of the trench is hard, sand be 10 cm thickabove and below the cable shall be provided.

The single layer brick protection shall be provided. If the trench bed is already contain soft sand bed then

additional sand bed of 10 cm above and below the cablenot needed.


5/11

Excavation of trench in water log area

Trench specification same as for normal soil.

Water deposited shall be removed with pump before

preparation of trench.

The sand bed of 10 cm thick shall be provided along thebottom above and below.

The back filling of the trench should be immediately.


6/11

Laying in standing water area

If the height of water is one meter or above other than

seasonal water.

The cable shall be laid directly on the surface of the earth.

The cable should cover with grouted back (dry) withcement sand ratio 1:8.

The size of bags (100*50*20 cm) shall be placed

longitudinally on cable.


7/11

Excavation of trench in Rocky soil

The trench depth shall be 110 cm.

The top width 40 cm and bed 35-40 cm.

All the sharp edges of rock should be removed.

The sand cushion 20 cm thick above and below the cableshall be provided.

The small pebbles shall be dropped first in the trenchgently till the level of warning tape.

material The optical fiber warning tape is used at 50 cm

from bottom of the trench and then back filling with same


8/11

River Crossing

When the trench cross a river where small quantity

of water flows then the river shall be crossed

through bore using GI-pipe sub ducted with PVC

pipe and slab shall be used.


9/11

Rain Washable Areas

The depth of the trench shall be as per

specification but instead of using bricks, the sand

bed above the cable shall be covered with 15cm

thick concrete. Under no circumstances the cableshall be directly concreted.


10/11

Slope Crossing

When slope to be passed down, the cable shall be laid inGI/PVC pipe.

The trench depth shall be one meter at the base of the slopeand 50cm at the top.

Concrete step wall having 1m Length, 0.5m Height and0.15m Thickness shall be constructed after every 2 metersacross the trench.

The wall shall be constructed from the level of pipe intrench.


11/11

Laying of cable in a Trench

The handling of Fiber cable is critical and care shall betaken.

Cable shall be laid in a straight line along the bottom andcenter of the trench.

Cable shall be carefully rolled off the drum preventingsharp bends and kinks.

It is necessary to remove the cable from the drum and storein the shape of EIGHT (8) when the cable is to passthrough a pipe.

session-4 (optical fiber laying)

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