Round cable fastening solutions for overhead lines

Enabling the roll-out of outside plant ultrafast broadband networks on MV, LV or telecommunications networks, ADSS (All Dielectric Self-Supported) cables are effective solutions for the transmission and distribution of optical signal. Their main benefit consists in their design: ADSS cables are developed with a reduced diameter and they offer a low overall weight. This makes it possible to relieve poles and thus to permanently preserve the operated infrastructure. In addition, the non-metallic structure of ADSS cables provides an anti-lightening protection, eliminating thus the risk of network failure caused by natural hazards.

anchor clamps for dead-ending applications on round ADSS aerial optical cables

Depending on their structure and the manufacturer's specifications, ADSS cables are used for deploying a telecom network segment in overhead or underground configurations, for indoor installation or, in case of multi-function ADSS cables, for a discontinuous installation implying outdoor-indoor or overhead-underground transitions. In that respect, ADSS cables with loose tube structure are notably used for the deployment of feeder networks. Micro-bundle or cables with a stranded structure are preferred instead for the rollout of distribution networks as they offer an increased flexibility and an easier access to the fibre.

In order to guarantee future-proof overhead lines rolled out by using ADSS cables, it is essential to pay a particular attention to dead-ending and suspension clamps. Together with the cable, these accessories form a cohesive unit. Hence, they must meet compatibility criteria. Here are the main elements to check before selecting the right ACADSS clamp or the most suitable suspension device for your cable:

  • the outer sheath diameter
  • the maximum allowable tension, also called tensile load short-term
  • the minimum bend radius
  • climatic conditions specific to the installation environment

What to choose for the dead-ending of ADSS aerial cables ?

To meet the anchoring and the suspension needs of various ADSS round cables, several technological solutions are available. Thus, for the deadending of aerial ADSS round cables, rolled out on spans up to 70 meters, anchor clamps with enveloping wedges are the most suitable solution. Indeed, these clamps are designed with specific wedges perfectly fitting onto the cable’s shape and enabling thus to preserve all the functional characteristics of the cable in case of overload.

For anchoring applications of ADSS aerial cables with round structure and HDPE sheath rolled out over longer spans, up to 90 meters, compact body clamps or ACADSS clamps are the solutions to consider. Nevertheless, these two models are developed for different anchoring situations. Here are the main differences between these two anchoring solutions:

Solution

ACADSS C clamp

ACADSS clamp

Body

Compact

Standard

cable Ø (mm)

6-14

9-19

Cable clamping length(mm)

165

230

The anchoring of aerial ADSS cables can also be performed with helical dead-ends. The advantage of these deadending solutions is that they provide a wider contact surface with the cable than anchor clamps. Thus, for spans up to 90 meters, AADE spirals (Aluminum Alloy Dead-Ends) or GSDE spirals (Galvanised Steel Dead-Ends) are the most appropriate solutions. However, the two ranges meet different anchoring needs. Designed with relieved ends, AADE spirals are compatible with ADSS cables of diameters 4.8 to 15mm and enable the sag adjustment before the complete cable installation into the device. As for GSDE spirals they cover a wider range of permissible diameters(4.5 to 19mm) and are used for a maximum load of 3.5 kN.

For cable roll-outs characterised by longer spans, up to 180 meters, the GSDE AR are most convenient solutions. Including an armor rod in their construction, these dead-ends are used for the termination on brackets or cross-arms of aerial ADSS cables with Ø 10.5 to 18.6mm.

What to choose for the suspension of ADSS round cables ?

Aerial ADSS round cables are fixed onto intermediate utility or telecom poles with fastening devices especially developed for the purpose. For the unrolling, tensioning and suspension applications of ADSS round structure FO cables with Ø 5 to 17mm, rolled out over short spans, up to 70 meters, J hook clamps such as those included within the JHC range are an appropriate choice. Thanks to their particular design, the cable unrolling is performed directly into the clamp’s J-shaped body, once that integrated protective sleeve is removed. Depending on the pole hardware used for their installation, JHC clamps can be used as fixed suspensions (installation with pole band and pole head bolt) or mobile suspensions ( installation with pigtail bolt).

Also intended for short span overhead configurations of up to 70 meters, DS clamps are mobile suspension solutions compatible with ADSS cables with round structure with Ø 2 to 8mm. These suspension devices consist of a hinged plastic shell equipped with a protective insert and an opening bail.

For the suspension of ADSS cables on MV networks characterised by longer spans, up to 180 meters, DSAL suspension devices are the appropriate solutions. These suspension clamps consist of an aluminum hinged body with an integrated elastomer protective sleeve. Once that the cable is set into the suspension clamp, its shell body secures with an integrated and captive bolt system.

How to avoid damage risks on ADSS cables ?

In addition to ensuring a perfect compatibility between the anchor clamps or suspension devices and the cables to be rolled out, the best way to guarantee reliable and future-proof networks is to ensure strict compliance with the ADSS cable installation instructions.

Often, during overhead line deployments, incidents related to fiber breakage or high loss point can occur. Contrary to the most prevelant belief, these incidents are not due to a lack of cable quality, but to a wrong deployment process consisting into applying an unacceptable tension to cable during its overhead laying. It is therefore essential to apply a regular tension and speed to aerial ADSS cables during their roll out.

It is also common that ADSS cables present broken fiber at poles. To avoid this, it is essential to pay a particular attention to the tension and the angle of optical fibers during the overhead deployment.