Soil physical route survey and cable thermal design procedure

A thermal rating procedure is proposed for cables buried in sandy soils. The procedure uses a recently developed model to account for the effects of drying-out. The model requires as soil characteristics density, suction tension curve and saturated hydraulic conductivity. As boundary conditions it requires the ambient temperature and moisture content at cable level. In a reconnaissance survey of the cable route the thermally limiting soil sections are identified on the basis of estimated soil properties and local hydrology. Soil characteristics are determined in the laboratory for these sections only. The worst-case moisture content is derived from the lowest water table expected as indicated by hydromorphic characteristics of the soil profile