When several cables are buried in soil

there is thermal infection among cables.This effect makes the ampacity of every cable reduced.The ampacity of every cable can be calculated by the formula introduced by IEC 60287.The environment temperature in the formula is the sum of soil temperature and temperature rise caused by other cables.The temperature rise caused by other cables can be calculated by the method of mirror image.So

the ampacity of every cable will be decided by other cables

Gauss-Seidel iterative method is used to solve the equation group which is consisted of ampacity of different cables

and calculate the ampacity of equally load and unequally load and different environment condition.The test result shows that the calculating result conform to the request of project.