Water blocking is a construction feature that stops moisture travelling along the inside of a cable. Swellable tapes or yarns are placed under the sheath, and sometimes within the conductor; the moment water reaches them they swell into a gel and seal the path. It matters because a small nick in the outer sheath of a buried cable lets water in, and without blocking, that water can migrate metres along the core and sit against the insulation, degrading it slowly until the cable fails somewhere far from the original damage — which also makes the fault harder to locate and repair. For cables that will spend their lives underground, in ducts that flood, or in high water-table areas, it's a feature worth specifying at enquiry stage, not after laying.
Quick answer
People also ask
Why are single-core cables laid in trefoil formation? Because three single-core cables each throw off a magnetic field, and how you arrange them decides whether those fields… What is the difference between a covered conductor and an insulated cable? A covered conductor has an XLPE covering bonded over an overhead line conductor — enough insulation to survive touching… Do I need individually screened instrumentation cable, or is an overall screen enough? It depends on whether the pairs inside the cable can interfere with each other, not just on outside noise. A collective…
Looking for the right cable for your project?
Get expert guidance on grade, size and standards from APAR Cable Solutions.