IEC 60502 is an International Electrotechnical Commission standard, which gives current ratings for medium voltage cables.  The calculation of cable rating follow the derating factor method, see . 

The IEC 60502 standard is in two parts; part 1 for voltages up to 1 kV and part 2 for voltages from 1 kV to 30 kV.  Part 1 does not contain any current capacity sizing, as this is intended to be covered by IEC 60364.  Part 2 Annex B, has a calculation method for determining current capacities for voltages covered by this part.

The current rating tables include three phase cables both installed in the air and buried.  Derating factors considered are the ambient temperature, depth of laying and soil thermal resistivity for buried cables, and the grouping of cables.