Single or multicore cable with synthetic or rubber insulation - has moisture sensitive tracer which exhibits permanent colour change when exposed to water

摘要

Along the cable core (1), for example a dry type telephone cable, a tracer thread or strip (9) is included which lies between the core and the outer insulation sheath (2). The tracer incorporates a hygroscopic material, typically a die, which changes its state permanently when affected by the ingress of moisture between core and sheath. The visual indication of the presence, or one time presence, of moisture is confined to the linear extent of the moisture penetration. The affected length can thus be established visually enabling the minimum amount of cable to be cut out and thereby avoiding waste. The hygroscopic material can be incorporated in the tracer used for cable identification, or in the binding ( for individual conductor groups. It can be a material which, when wet spreads over and colours a considerable area of the affected length.