IEC TR 62691:2011 pdf – Optical fibre cables – Guide to the installation of optical fibre cables
IEC TR 62691:2011 pdf – Optical fibre cables – Guide to the installation of optical fibre cables.
ISO IEC TR 29106, Information technology — Generic cabling — Introduction to the MICE
ITU-T Recommendation K25, Protection of optical fibre cables
ITU-T Recommendation L.35, Installation of optical f,bre cables in the access r,&wurk
ITU-T Recommendation L,38, Use of trenchless techniques foi’ the construction of underground infrastructures for telecommunication cable lnstallaton
ITU-T Recommendation L.57, Airassisted installation of optical fibre cables
ITU-T Recommendation L.61, Optical fibre cable installation by floating technique
ITU4 Recommendation L77, Installation of optical fibre cables inside sewer ducts
3 Installation planning
3.1 InstallatIon specificatIon
The successful installation of an optical fibre cable can be influenced significantly by careful planning end assisted by the preparation of an installation specification by the user, The installation specification should address the cabling infrastructure, cable routes, potential hazards and installation environment and provide a bill of materials and technical requirements for cables, connectors and closures.
The installation specification should also detail any civil works, route preparation (including drawpits, ductwork. traywork and trunking) and surveying that are necessary, together with a clear indication of responsibilities and contractual interfaces, especially if there are any she or access limitations.
Post installation requirements for reinstatement, spares, ancillary services and regulatory issues should also be addressed.
3.2 Route considerations
Whilst optical fibre cables are lighter and installed in longer lengths than conventional metallic cables, the same basic route considerations apply.
Route planning and cable handling methods must carefully take into account the specified minimum bending radius and maximum tensile loading of the particular optical fibre cable being installed so that fibre damage, giving rise to latent faults, can be avoided.
Some of the most difficult situations for the Installation of optical fibre cables are In underground ducts and the condition and geometry of duct routes is of great importance. Where the Infrastructure includes ducts in poor condition, excessive curvature, or ducts already containing cables or access points with abrupt changes of direction, the maximum pull distance will be reduced accordingly.
Provision of tong cable lengths In underground duct or aerial situations may involve Installation methods that require access to the cable at intermediate points for additional winching or blowing effort, ot iigure 8 techniques, these sites should be chosen with care. Consideration should also be given to factors of time and disturbance. Installation equipment may be required to run for long periods of time and the time of day, noise levels, and vehicular traffic disruption should be taken into account.
Because the condition of underground ducts intended for optical fibre cable is of particular importance, care should always be taken to ensure that ducts are in Sound condition and as clean and clear as possible. Consideration can also be given to the provision of a sub-duct system, either in single or multiple form, to provide a good environment for installation, segregation of cables, extra mechanical protection and improved maintenance procedures. Sub-ducts can be more difficult to rope and cable than normal size ducts, particularly over long lengths, and me diameter ratio between me cable and subduct should be considered. Note that In ducts or subducts. bundles of microducts can also be Installed. e.g. by pulling or blowing.
For overhead route sections, a very important consideration is the need to minimise in-service cable movement. Movement of the cable produced by thermal changes, cable weight, ice loading, wind. etc. may have a detrimental effect. A stable pole route, with all poles set as rigidly as possible, is therefore an important element in reducing possible movement and consideration should be given to purpose-designed, optical fibre-compatible, pole top fittings and attachments.
Although optical fibre cables are generally light in weight, their addition to an existing suspension member can take the optical fibre beyond its recommended strain limit and the added dip and extension should be calculated before installation.
Where it is planned for long lengths of optical fibre cable to be directly buried or ploughed, those sections involving ploughing can, with advantage, be pre-prepared using specialised slitting or trenching equipment
3.3 Cable Installation tension considerations
The potential for providing very long lengths of optical fibre cable can lead to the need for confidence that a particular installation operation will be successfully achieved, particularly in underground ducts, and a good indication can be provided, in some cases, by calculating the maximum cable tension. This maximum tension can be compared with the stated mechanical performance of the cable and, where these values are close, consideration can be given to methods for providing a greater margin of safety such as an alternative cable design. shortening the route, changing the route or direction of cabling, provision of intermediate winches, or by taking special precautions at particular locations. Calculation considerations are Indicated In the clauses which follow.