Laying the optical drop cable in the FTTH


Laying the optical drop cable in the FTTH: Today, in this topic, we will discuss what is Drop Cable in FTTH Network? How do the laying of it? What are the parameters etc.Every country has a different way of working on FTTH network, but we will discuss about the parameter that most countries work on.In this topic we will discuss only drop cable of FTTH network.


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FTTH drop cables are located at the end of the customer to connect the terminal of the delivery cable to the customer's premises. They are usually small diameter, with low unsupported duration length, low fiber counting cables, which can be aerially, underground or buried. Since it is used in the outdoor, the dropping cable will have the minimum pull power of 1335 Newton according to the industry standard.Fiber optic drop cables are available in many different types. The three most used fiber drop cables include flat drop cables, figure-8 aerial drop cable and round drop cable.Now I will focus on this point that  how to do the trenching and cable laying of drop cables in FTTH network.

Small Trenching For Drop Cable

Drop cables are available from the FTTH MH / HH to the customer's building.This cable carries itself to the building wall of the customer.Drop trenching is to be used to install drop ducts between MH/HH and customers. The dimensions of this trenching is 130mm width and 450mm depth. This trenching can accommodate from 2 drop ducts to a single customer up to 24 (20mm) drop ducts to serve 12 customers.

Optical drop cable in FTTH up to the customer building wall
Drop cable to the customer building wall

Micro Trenching for Optical drop ducts (No Sharing)


Trenching, described in this section, is to be used from handhole to customer. Trenching size, in this case, must be 100mm width and 350mm deep from ground level. The number of drop duct groups that can be placed within the same trench must not exceed 12 groups, one group for each building/lot.

Optical drop trench in FTTH network without sharing
Optical drop trench in FTTH Network

Micro Trenching for Optical drop ducts (With Sharing)

Trenching size, in this case, must be 100mm width and 400mm deep from ground level. The number of drop duct groups that can be placed within the same trench must not exceed 12 groups, one group for each building/lot.

Optical drop in FTTH network
Optical Drop Ducts in FTTH Network

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Optical Drop Cable in FTTH

Optical drop cables shall be used in OSP installations from Fiber Access Terminal (FAT) distribution closures to Fiber Termination Box (FTB) at the customer premises. This type of cables shall be installed in ducts using traditional manual pulling method or by air blowing technique.

Outdoor fiber optic drop cables shall be able to be installed inside micro-ducts with nominal internal diameter of 11.0mm. Optical drop cables shall be metal free in construction.The outer sheath for optical drop cables shall provide the cable with a protective covering, which can withstand normal duct installation and service. Optical drop cables shall be designed according to the requirements.

Generally optical drop cable size used in FTTH network are 2, 4, 12 and 24 (Number of Fibers).There are three types of optical drop cable used in FTTH network. See the below image.

Type of optical drop cable
Type of optical drop cable

Normally ITU-T G.657 type drop cable used in FTTH network which have Dispersion Un -Shifted / Zero-Dispersion, Single Mode (SM) Fibers with Zero Water Peak (ZWP), operating at O-Band (1310nm), C-Band, L-Band (1530nm ~ 1625nm) and E-Band (1400nm), Diameter of cable size used 2.5 mm, maximum, (up to 24 fibers per tube).

According to the consumer or according to the size of the building,optical drop cables are laid from MH/HH to the customer end.A ODB is installed to the wall of the customer's building in which the optical drop cable is terminated.

How to lay Optic drop cable in FTTH network


Short sections of optical drop cable can be pulled by hand, (less than 300 meters). Maximum allowable pulling tensions is 2 kilo Newton but for optical drop cable minimum pulling tension allowable of 1335 Newton. There are two way for the laying of optical drop cable in FTTH network.Which I will tell in detail.

Unidirectional Laying of Optical Drop Cable

If the pulling wire is to be used, verify that it is continuous throughout the pull.At the reel-end manhole/HH, install the cable conduit . Attach the pulling wire or winch line to the cable using the pulling hardware.Verify that the set screws are well tightened on the central strength member of the cable.

Start pulling at low speeds. When the drop cable enters the duct and it is verified that there are no obstructions, pulling speed can be gradually increased to 20 meters per minute. When the drop cable reaches a pull-through HH up to the customer end, reduce the pulling speed until the cable has pass out to the customer building.Use cable lubricant on the cable if required during the pulling.

Bidirectional Laying of Optical Drop Cable

This method of placing requires equipping the cable with a pulling eye at each end. Well this method does not need for laying the drop cable in the FTTH network,its generally used for the long distance network.The cable must be pulled at a lower speed (10 meters per minute) to facilitate an easy feeding of the cable into the duct without twisting.Keep enough drop cable coil at the ends of customer building for the proper termination of drop cable in ODB.

Finally optical drop cable terminated at customer building wall.Showing image below. I think it would be enough for you to understand where the drop cables are from and where does the terminate happen.

Optical drop cable terminated in ODB at customer building wall
Optical Drop Cable terminated at customer building wall 



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