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Discuss Circuit design in the Electrical Wiring, Theories and Regulations area at

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  1. zsoltimatrix

    zsoltimatrix Electrician's Arms

    Hi all!

    When you are designing new circuits, do you design for both overload and fault protection for every case? Or for fixed loads design without overload protection and make adiabatic check as well?
  2. xraytek

    xraytek Guest

    I usually find that when the adiabatic equation is used the earth conductor size is suprisingly small, and that the CPC size in T&E is always more than adequate.

    But as far as designing a circuit goes I think you are always supposed to make the calculation unless CPC is the same size as the line conductors.

    The design procedure is:

    1) Calculate design current (applying diversity if nessessary)
    2) Select MCB
    3) Select cable based on MCB and check voltage drop.
    4) Calculate Zs (Ze+R1+R2) and then fault current
    5) Calculate minimum CPC size using adiabatic
  3. ezzzekiel

    ezzzekiel Guest

    Protective devices are installed to protect the cable of the circuit from
    damage – overload, overcurrent and fault current.​
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