Including Soil Drying Time in Cable Ampacity Calculations.

Previous papers proposed a method to find the maximum possible dried area of soil expected due to heating by underground cables. A method was also proposed to include this dried soil area in cable ampacity calculations. This assumed that cables would be loaded 100% of the time. To dry soil to the maximum possible extent may take very long time periods, and in many installations, the cables actually carry current for a limited time. In these cases, the soil may never dry to its maximum extent. This paper proposes a method to approximately determine the radius of dried soil that will occur due to cable heating for limited periods of time. It similarly proposes a method to approximate the time it will take for the dried soil to be replenished to its original moisture content after heating by the cables has ceased. [ABSTRACT FROM AUTHOR]