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Electrical question No.17 – Parallel Electric Cable

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  • #172

      Hi, I am upgrading power transformer from 220 KVA to 400 KVA due to increase in load. I have 185mm running from Power transformer to 400 V, 3 Phase distribution system.
      Distance between transformer to distribution panel is 76 meters. Since my load would increase to 400 Amperes therefore I would need to upgrade 3 core cable as well. I was thinking to add another 95mm 3 Core cable and a 48mm cable for neutral which would run PARALLEL to 185mm cable.

      Is it ok to do that?

      I am in Pakistan and system is similar to UK electrical system with 400 KVA Transformer, 3 Phase system with 400 Volts and single phase with 220 Volts.

      I am not concerned much about neutral cable because most of the heavy appliances are of 3 phase.

      Would appreciate your comments.

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    • Author
    • #1366

        With 400A load currents, condition of voltage drops and cables ampacity will be better in comparison old situation. Of course it should not forget that we must support whole capacity of power transformers (600A) for future consumers. Also when we use two individual power cables instead one greater cable, we must care of cable shields capacity. Only if the ratio of phase wire cross section in two individual cables is same of ratio of two neutral cross sections, we have not any unbalance flux due to unbalance loads. As you know over unbalance flux can create over eddy current in cable shields.


          hey no problem for laying 95mm in parallel with existing cable. But As Hamid said better to put cable for whole capacity of Transformer

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