Simulation of the thermal trend of electric cables to define the admissible current

The present paper reports the study carried out to evaluate the admissible current flowing in electric cables, when they have different sizes and are disposed in the same duct. The standards treating this argument are CEI-UNEL 35024/1 and CEI 20-65, where several methods to determine the admissible current, considering the mutual influence between the near cables on the temperature, are proposed, but they give too small values for the cables of high cross sectional area. To find out new methods, FEM models have been studied and validated with experimental tests. Some corrections of the standard methods are proposed; in a few dispositions of cables, they give higher current values but within the safety limits.