Underground Cable Thermal Backfill documents the proceedings of the ""Symposium on Underground Cable Thermal Backfill,"" held in Toronto, Canada, 17-18 September 1981. The symposium brought together research, design, and installation engineers from utilities, cable manufacturers, and universities to present and discuss developments in the field. The contributions of researchers at the symposium are organized into five chapters. Chapter 1 presents an overview of the state-of-the-art of cable backfill materials and soil thermal property measurements. The papers in Chapter 2 deal with developments in cable backfill materials. These include materials stabilized with moisture substitutes, pumpable materials, and materials stabilized with bound water. Chapter 3 covers thermal property measurements of soils and backfills. Through the automation of measurements and analysis using microprocessor based instruments and better control of experimental conditions, substantial improvements have been made in the area of measurement technology. Chapter 4 reports developments in the study of soil thermal stability and the implication thereof for thermal cable design. Chapter 5 discusses various aspects of thermal cable design, including methods for incorporating historical weather records to predict worst case soil and backfill thermal conductivities. This volume should serve as a useful introduction to the subject of cable thermal design for engineers involved in underground transmission and distribution systems.