Strand filling is available in the U.S. for 5kV and above. In addition, some 600 volt applications are starting to use strand filled material. Other than preventing treeing, water blocking with strand filling material will also block gases from hazardous areas or the migration of other chemicals in the conductor. Hygroscopic Materials Water absorbing materials are off white powders of many different types. These powders can be organic or inorganic.
Organic materials degrade after exposure to water.
Inorganic materials will remain stable after absorbing water. Water absorbing materials are placed into the interstices of the conductor during the manufacture of the conductor. These materials will absorb water and become a viscous gel. This gel will then block the ingress of more water penetration between the strands. These powders can be placed into the conductor directly or brought into the conductor with yarns or tapes.