Waterproofing of insulated electric cables

摘要

The invention provides for the waterproofing of a telephone cable by the incorporation of longitudinal strands within the sheath alongside the insulated conductors. The strands have deposited thereon a moisture sensitive swelling agent, such as ethyl hydrogen cellulose, and in the event of the sheath rupturing and the conductors being exposed to moisture the swelling agent on the strands reacts with the moisture rapidly forming a plug which prevents further ingress of the moisture.