Dear Guys, It will be really helpful if some one can give me the calculation step by step or some calculator where in I can resolve my long pending problem. Thanks in advance I will be really glad to have a correct answer. The Q is below Calculate temperature rise in 3 core cable after 3 hrs. resistance 2.74 ohms/km at 20c . Ambient temperature is 33.4c . Length of cable is 140 meter and current passing through cable is 24.97amp this is three phase connection so I will be= 24.97/1.732. Size of each core is 6.30 sqmm density of copper 8.89. So weight of copper in 3 core cable 140 meter comes to: 23.52kg copper.