What are the longitudinally and laterally water-resistant cables?

Cables designed to be submerged in water or in constant contact with water are usually designed to be both laterally and longitudinally watertight. This doesn't necessarily mean they're entirely water-resistant, but if they're installed in ducts liable to permanent or even intermediate flooding, providing additional protection for sheathing materials that are ultimately permeable can be essential.

Laterally watertight ensures that water can't penetrate into the cable in the event the sheathing is pierced or damaged. Longitudinally water tight cable is designed with a barrier to the spread of moisture along the cable length.

Longitudinal water-tightness can be achieved in a number of ways including the use of water-blocking or water swellable tapes and water swellable powders. They are often found either side of a metallic screen. Lateral water tightness is commonly achieved by a layer of Aluminium/Polyester tape bonded to the underside of the outer sheath.

Additionally, Class 2 stranded conductors can have water swellable yarns or swellable powders in between the interstices of the stranding to help prevent propagation along the length of the cable in the event of ingress at the point of termination.

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1142-2009 - IEEE Guide for the Selection, Testing, Application, and Installation of Cables having Radial-Moisture Barriers and/or Longitudinal Water Blocking

Abstract:
Detailed information relating to the design, testing, application and installation of various types of electrical cables in order to prevent the deleterious effect of moisture and chemical ingress and resultant failures in service is provided in this guide. This includes single and multi-conductor cables over a complete range of voltage ratings. Testing criteria and installation methods covered along with many technical references.
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 addr...
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 ...
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Date of Publication: 26 March 2010
Electronic ISBN:978-0-7381-6151-8
DOI: 10.1109/IEEESTD.2010.5440108
ICS Code: 29.060.20 - Cables


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The main difference between laterally and longitudinally waterproof cables lies in how they prevent water ingress.

Laterally Waterproof Cables:

Purpose: These cables are designed to prevent water from entering through the sides of the cable.

Mechanism: They typically use materials like aluminum/polyester tape bonded to the underside of the outer sheath to create a barrier against water.

Application: Useful in environments where the cable might be exposed to water or moisture from the sides, such as underground installations or outdoor settings.

Longitudinally Waterproof Cables:

Purpose: These cables are designed to prevent water from traveling along the length of the cable.

Mechanism:They often use water-blocking or water-swellable tapes and powders that swell upon contact with water, effectively sealing off the affected area.

Application: Essential in scenarios where water might enter the cable at one point, such as at a connector or a damaged section, and then spread along the cable.



As a result, laterally waterproof cables protect against side water ingress, while longitudinally waterproof cables prevent water from spreading along the cable's length. Both types are crucial for maintaining the integrity and reliability of cables in wet or moist environments.


Source: IEEE 1142-2009 - IEEE Guide for the Selection, Testing, Application, and Installation of Cables having Radial-Moisture Barriers and/or Longitudinal Water Blocking

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