IEC 60794-4-20:2018 covers optical telecommunication cables, commonly with single-mode fibres used primarily in overhead power lines applications. The cables can also be used in other overhead utility networks, such as for telephony or TV services. Requirements of the sectional specification IEC 60794-4 for aerial optical cables along electrical power lines are applicable to cables covered by this document. This document covers the construction, mechanical, electrical, and optical performance, installation guidelines, acceptance criteria, test requirements, environmental considerations, and accessories compatibility for an all dielectric, self-supporting fibre optic (ADSS) cable. This document provides construction and performance requirements that ensure, within the guidelines of this document, that the required mechanical integrity of the cable components as well as optical fibre mechanical reliability and transmission parameters are maintained. The ADSS cable consists of single mode optical fibres contained in one or more protective dielectric fibre optic units surrounded by or attached to suitable dielectric strength members and sheaths. The cable does not contain metallic components. An ADSS cable is designed to meet the optical and mechanical requirements under different installation, operating and environmental conditions and loadings, as described in Annex B. This document excludes any "lashed" or "wrapped" OPAC cables included in IEC 60794-4. Figure 8 aerial cables are also excluded; they are specified in IEC 60794-3-20. This second edition cancels and replaces the first edition published in 2012 and constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- this document has been streamlined by cross-referencing IEC 60794-1-1,
- IEC 60794-4 (all parts) and IEC 60794-1-2;
- reference to the MICE table has been deleted;
- the example of test method for particular environment in Annex C has been deleted;
- creep test method has been updated in Annex E.

Keywords: optical telecommunication cables, single-mode fibres used primarily in overhead power lines