scope:

This guide provides cable manufacturers and users with extensive information on the design, testing, application, and installation of low, medium, and high-voltage power cables, as well as communication, control and instrument cables that make use of metal-plastic laminates as radial-moisture barriers. This guide addresses additional means of protecting cables from the entrance of moisture through the use of polymeric super absorbent materials for longitudinal water blocking of stranded conductors and other spaces within cables. The alternate use of extruded metal sheaths or bare, longitudinally applied, metallic tapes with sealed seams will likewise be addressed.

Purpose

While metallic sheaths, such as lead and aluminum, have been effective in past years as barriers to moisture, their relative cost, environmental concerns along with installation difficulties have led to the search for alternatives. Alternatively, thin metal-plastic foils are finding application as moisture barriers in low, medium, high, and extra-high voltage power cables. Aluminum, copper, or lead substrates are coated with polymeric coatings on one or both sides and adhesively bonded to the cable jacket or over sheath. The tapes are usually applied longitudinally, with an overlap, or seam, that is adhesively sealed over the core of the cable and under the jacket. In addition, other measures have been taken to block the longitudinal movement of moisture through the conductor and the shield interfaces so that water-impervious cables are now available. This guide will provide information on the use of such coated metals in cable constructions as well as the use of other materials for longitudinal water blocking. Cable users should find this information of value in the selection, specification, installation, and testing of cables having radial-moisture barriers and/or longitudinal water-blocking systems.

There is an extensive amount of information in this guide that refers to IEC Standards, British Standards and CIGRE study group recommendations. These organizations, and others, have developed recommendations, standards and specifications that are pertinent to cables with radial-moisture barriers and longitudinal water blocking. Inclusion of a discussion of these documents presents the user of the guide with a more complete picture of the degree to which cables with radial and longitudinal moisture protection have developed. The technology has matured greatly since this guide was first published and inclusion of all pertinent information not only serves to better inform the user of the guide but also documents how extensive and prevalent the technology has become globally.