What are 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.

Our range of longitudinally and laterally waterblocked cables include our medium voltage N2XS(FL)2Y and NA2XS(FL)2Y.