Everything you need to know about telecom overhead cable fastening

To better prepare each telecom overhead roll-out project, an assessment of needs must be carried out upstream. The choice of a suitable passive equipment is first of all based on the analysis of criteria related to the configuration of the telecom network. Here are the engineering rules that will let you know when to use a dead-ending or a suspension clamp:

Network configuration

Dead-ending

Suspension

Road crossing

Yes

No

Asymmetric span

Uneven adjacent spans

Even adjacent spans

Deviation

Angle >25°

Angle <25°

Alignment segmentation 

Every 5 poles

Up to 4 poles

Rugged terrain

Yes

No

Once the choice between anchoring or suspension is made, a plethora of overhead cable fastening devices is available to you on the telecommunications market. Here is what you need to determine before selecting your network hardware:

  • The telecom network segment on which the cable fastening device will be installed
  • The type of cable to be anchored or suspended
  • The length and nature of the span
  • The environmental constraints 


The FTTH infrastructures are organised into three main segments: the feeder, the distribution and the last mile access network. The feeder, also called the trunk network, is the segment between the Point of Presence or the Optical Connection Node and the Fiber Distribution Point (FDP), a flexibility point in FTTx infrastructures. The feeder makes the connection between the backbone, usually represented as a vertical network, and the horizontal network that hauls the optical signal to the end-users via an optical splitter. This splitter, usually placed in a street cabinet together with distribution panels or at the building’s entry level, plays the role of an intermediate cross-connect point. It is also the starting point of the optical distribution that goes generally up to a Fiber Distribution Box (FDB). Finally, the last mile access network or the local loop is the cable segment that links the Fiber Distribution Box to the Optical Telecommunications Outlet, installed at the end-user’s premises.

Depending on the spot of the network where the cable fastening device is to be installed, the required performances are different. The choice between anchor clamps and helical dead-ends must be made based on whether or not they were designed to meet specific applications.

Which dead-ending solution for telecom networks over LV lines?

The various anchoring and suspension technologies available on the telecommunications market correspond to particular cable structures. As regards low-voltage lines, the ADSS (All Dielectric Self Supported) round optical cables are widespread and acclaimed for deployments on distribution networks mainly because they are self-supported , rugged, lightweight and with a reduced diameter. Clamps with enveloping wedges offer a high performance solution for ADDS round cable fastening applications in aerial network configurations. These devices for drop cable fastening are engineered for installation without bend radius constraint on the optical cable and can cover a wide range of cable diameters.

For the dead-ending of flat optical cables, aerial cable clamps such as those included in the  5/35 FTTH F range are available. These flat cable fastening solutions enable a manual sag adjustment.

To terminate figure-8 cables with dielectric messenger on feeder or distribution telecommunications networks, optical cable clamps  from the ACAL range designed with aluminum body are an excellent solution for figure-8 cable fastening applications. These clamps offer an easy, fast and toolless installation.

Dead-ending and suspension clamps for the installation of ADSS round, flat or figure-8 overhead cables

An adapted suspension device for each telecom cable

The suspension of ADSS cables with round structure can be performed with helical dead-ends such as those included in the AADE or the GSDE ranges, enabling an excellent cable grip. These distribution cable fastening solutions are available in versions with or without armor rods. Versions including an armor rod can be installed on the feeder network as well, where spans are longer and tensile loads register higher values. To choose the suitable model, it is therefore necessary to take into account the type of network on which the anchor clamp will be installed, as well as the span of the network configuration.

For the suspension of flat cables, on intermediate poles, mobile suspension devices can be installed as they are simple to use, discreet and effective. 

As for the suspension of figure-8 cables, this application can be performed with clamps from the SC range, engineered to adapt to both copper cables with steel  messenger and to optical cables with dielectric messenger.

Choosing the right telecom equipment for your installation environment

In addition to the network configuration defined by the topography of the terrain, the deviation, the alignment of the telecom line or the road crossing condition, two other criteria are essential to make an informed choice for the fastening of overhead telecom cables: the span and the installation environment. Depending on the span length (the distance of the aerial cable deployed between two poles), the anchor or suspension devices meet different performances. Here is a short explication of the different models of anchor or suspension clamps and helical dead-ends:


Type of network

Span

Cable clamping solution

Feeder network

from 180 up to 250 meters        

Anchor clamp for long span or helical dead-ends with armor rod

Distribution network 

from 90 up to 180 meters

Helical dead-ends with or without armor rod

Last mile access

from 70 up to 90 meters

Drop clamp


The last selection criteria but not least is the installation environment. Depending on the weather conditions and the mechanical loads which may apply on the passive network hardware, it is important to make sure that this hardware is designed ruggedly enough so to last.  In coastal areas characterised by strong winds, for example, helical dead-ends engineered to preserve the cable sheath from damage in case of overloads or aeolian vibrations such as those included within the AADE or GSDE range are to be preferred to any other less effective accessories for LV lines. Frost, snow or ice are some of the elements that can add mechanical loads to your telecom infrastructures. In order to build future-proof telecom networks, one should consider all the above mentioned factors before selecting the network hardware.