IEC 60287:1982

Deals solely with the condition of steady-state operation of cables at all alternating voltages, and direct voltages up to 5 kV, buried directly in the ground, in ducts, troughs or in steel pipes, as well as cables in air. The term
Note: - Appendix A Reference ambient temperatures, and thermal resistivities of soils in various countries.
Appendix B Information required from the purchaser for the selection of the appropriate type of cable.
Appendix C Digital calculation of quantities given graphically.