Presented by:Kamran BashirInspector I - Telecom

G e n e ra l - ( P l a c e m en t M e t h o d o lo g y)

P r e - S u r v e y

L o c a t i o n a n d D e p t h

P l o w i n g M e t h o d

Tr e n c h i n g M e t h o d

P l o w i n g v s . Tr e n c h i n g

F O C U n r e e l P r o c e d u re

A p p l i c a b l e E n g i n e e r i n g S t a n d a r d s fo r F O C - O S P E xe c u t i o n.

Placement methods for direct buried cable are essentially the

same as those used for placing direct buried copper cable.

However, it must be kept in mind that fiber cable is a high capacity

transmission medium which can have its transmission

characteristics degraded when subjected to excessive pulling

force, sharp bends, or crushing forces.

Fiber optic cables are more susceptible to performance degradation due to tight bending than copper cables. The minimum bend radius of each cable is relative to the cable diameter. A general guide line is that a cable under tension should not be exposed to a bend radius less than 20 times the cable diameter and a cable with no tension not to be exposed to a bend radius less than 10 times the cable diameter.

Standard FOC cable has maximum recommended pulling tension

of 600 lbs.

A pre-survey of the fiber cable

route is very important in

planning for a direct buried

optical fiber project. One of the

objectives of the pre-survey is

to determine where each reel of

fiber optic cable is to be placed.

The pre-survey will verify

construction methods, special

tools required, or possibly

require a revision of preliminary

splice location.

A good pre-survey and proper

planning will preclude reel ends

falling too close to roads,

creeks or any other undesirable

locations.

Buried fiber cable route locations are selected by the Outside Plant Engineering group.

When burying fiber optic cables that must cross ditches, avoid crossing locations that might interfere with natural drainage. Also, avoid areas subject to surface drainage that may result in subsequent washing away of soil and exposing of the fiber optic cable.

Plowing refers to the insertion of a cable into the ground through a hollow plow blade or by pulling the cable into the ground just behind the plow blade.

When plowing method is to be used for burying the optical fiber cables, verify and ensure that the route is pre-ripped before plowing in the fiber optic cables, so that obstacles can be identified and removed or necessary precautions taken prior to the actual placement of the cable.

Trenching is where a trench is dug,

the cable is placed into the trench,

and then the trench is backfilled.

Direct buried fiber optic cables shall be placed with a minimum cover of:

1200 mm, when placed with no additional protections.760 mm to 1200 mm, when placed inside polyethylene sub-duct.

250 mm to 760 mm, in rocks areas, when placed inside concrete encased conduit.Fiber optic cables shall not placed with less than 250mm cover in any situation.

IV. Plowing vs. Trench:

In general, the most desirable and economical method of cable placement in open area such as desert area is plowing. Here there will be fewer obstacles to impede the progress of the plowing equipment.

Advantages of Plowing:

Speed of installation in open areas.

Less ground disturbance than may be caused by trenching.

Disadvantages of Plowing:

Large size and high cost of equipment.

Requires skilled equipment operators, quality supervision, and equipment in good condition.

Possibility of damaging cables or under ground utilities.

In urban or sub-urban areas where

there can be many obstacles such as

underground utilities, side walk and

paved road crossings, trenching has

advantages.

Advantages of Trenching:

Lower cost of equipment.

Digging operation is separate from

cable placement.

Better depth control.

Less risk of damaging underground

utilities.

Provides the opportunity to place

conduit at the same time.

Disadvantages of Trenching:

Slower rate of cable placement than

with plow.

Not suitable for all soil, sands and

terrain conditions .

The “figure-eight” configuration should be used

to prevent kinking and twisting when the cable

must be unreeled. The “figure-eight” should be

approximately 4.5 to 9.0 meters in length. Each

loop should be approximately 1.5 meters to 4.5

meters in diameter.

PLOWING (typical trench dimension)

When plowing in fiber optic cable a

warning orange terra tape is placed 12”

below the surface of the ground directly

above the cable. Both the cable and

the warning tape are normally plowed

in at the same time.

TRENCHING:

When trenching ensure an orange marker tape is placed flat in the trench above

all open trench for direct buried fiber optic cables. The marker tape is to be

placed approximately 300 mm below grade.

MARKER POST

On the straight runs of buried

cable, marker posts shall be

placed no further than 100

meters apart. This clearly

indicate the route and to warn

the public and other workmen in

the presence of the buried cable.

CONT’N – APPLICABLE S TA N DA R D S F O R F O C - O S P

FOC TESTING

End-to-end testing shall be

carried out on all Outside

Plant fiber optic facilities

(define as the span of fiber

from the transmitter to

receiver) to document the

overall optical loss.

CONT’N – APPLICABLE S TA N DA R D S F O R F O C - O S P

All permanent pavement

and sidewalks must be

restored to the satisfaction

of proper authorities.

Verify that the surface at

grade level of the

excavated area is restored

to as good or better than

the original condition.

SATIP-T-624

CONT’N – APPLICABLE S TA N DA R D S F O R F O C - O S P

SAIC-T-5408

“Quality is never an accident; it is always the result of high intention”