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Thread: Installation rules paper 2 November 2019

  1. #1
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    Installation rules paper 2 November 2019

    A single phase 230Vac DB supplies the following loads through conduit :
    A: 4KW water heater, 15m from DB.
    B: 30Amp stover, 4m from DB.
    C: 1.5KW pool pump and 6KW heater, 12m from DB.
    2.1: calculate suitable cable size for each load?

    How do we answer this question, if using the voltage drop calculation we find that a 1mm cable is suitable for load A, which is not possible. Do we then answer the question by saying load A requires a 2.5mm cable using the rule 1mm=10amp. 1.5mm= 15Amp. 2.5mm= 25Amp.

    Will the marker allow this in the exam?

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    Load A draw more then 17A. I do not see how you can use 1mm. In witch installation method are 1mm allowed to carry more then 17A? You will need a 20A mcb. Voltage drop in the cable is (mv per amp per meter) and should be less than 5%. Don't see why you are worried about that over this short distance

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    You must not look at Vd only as the determining factor but also the current carrying capacity of the cable. The conductor you specify must be able to handle the load AND Vd must be in spec.

    Sent from my SM-N975F using Tapatalk

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    Thanks guy. Understood now

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