Choosing the right device for fastening telecom cables:
anchoring or suspension?
During a fiber optic overhead deployment or the extension of a copper line oftentimes, the telecom cable is the first available network equipment. To perform its roll-out on telecom and utility poles in the strict respect of engineering rules and for ensuring a durable implementation, two cable fastening solutions are to be applied: dead-ending or anchoring and suspension. The choice between an anchor clamp and a suspension device is to be naturally made by considering the structure of the cable to be rolled-out and above all, the configuration of your network. This article lists the essential information you need to know before choosing among all available technological solutions for overhead cable fastening applications.
Reference framework for securing overhead lines
The anchoring of copper or fiber optic cables is performed, depending on the segment of the network to be deployed, with a helical dead-end, an anchor clamp or a drop clamp. Anchor clamps enable the cable termination and absorb all the tensile stress previously exerted on the telecom pole or the cross-arm. Their installation is mandatory at the begining and the end of the telecom network, but also in the following cases:
- mandatory on every 5 poles in alignment configurations
- for each aerial-underground transition or every cable down-lead towards a distribution box
- when the line makes an angle superior to 25°
- at one side and another of road crossing
- in case of rugged terrain
- in case of uneven adjacent spans
Dead-ending of overhead telecoms cables: solutions and applications
To perform aerial cable dead-end applications, 4 technological solutions are available:
Anchor clamps with conical wedges
The principle of this technology is simple: the more you pull onto the cable, the more the cable tightens into the clamp. Anchor clamps with conical wedges are easy to install, require no tools and enable a manual cable sag adjustment. They are specially engineered for round cables with FRP rods or for figure-8 cables with steel or dielectric messenger. This technological solution is mainly widespread on distribution networks.
Drop mandrel clamps
This product solution is based on the self-tightening of the cable around the mandrel, which protects cables from piston effects. Easy to install and requiring no tools, drop mandrel clamps also enable a manual cable sag adjustment. This drop cable dead-end clamp is particularly recommended for the last mile access network because of its compatibility with small diameter cables without FRP rods and/or presenting a non-dense outer sheath construction.
Drop wedge clamps
Featuring a wedge design, these drop clamps are engineered to fit perfectly the cable’s shape and to ensure thus an effective cable grip. This solution is compatible with both round or flat cables, fiber optic or copper, deployed on last mile access networks where spans do not exceed 70 meters. An improved technology has been developed to meet the needs of stiff optical round cables: clamps with enveloping wedges. These anchor clamps for FTTH roll-outs enable to preserve all the functional characteristics of the cable in case of overload.
Using the preformed technology, helical dead-ends enable the aerial roll-out of round cables on feeder or distribution networks characterised by long spans. Thanks to a large contact surface with the cable, spirals prove their effectiveness even in difficult installation conditions. Discreet, these anchoring devices require however additional accessories and a longer installation time than other dead-ending solutions.
The telecom cable suspension: when and how to use it ?
Suspension devices are to be used on intermediate poles in rectilinear configurations and on a flat terrain. Their role is to keep telecom cables attached onto the overhead infrastructure so to preserve all their functional characteristics and thus, to guarantee reliable and long-lasting telecom networks. Telenco networks offers three different suspension technological solutions, enginereed to meet both the mechanical and environmental constraints and the strict requirements of major telecom operators:
J hook suspension clamps
This technology enables the deployment of telecom cables on several consecutive poles without using pulleys. J hook clamps can be installed on cross-arms (fixed suspension) or poles (fixed and mobile suspension).
Shell design suspension clamps
These enveloping clamps are used for the mobile suspension of round or flat drop cables. They consist of a hinged plastic body shell design, an elastomer protective insert and an opening bail. Shell suspension clamps can be installed on all type of poles.
Suspension grooved pads
This technological solution is highly recommended for the suspenion of figure-8 cables with steel or FRP messenger. Presenting two grooves, these suspension clamps can adapt to different messenger diameters.