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Thread: Earth continuity conductors

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    Earth continuity conductors

    In SANS 10142-1:2020, there are 2 tables with same description but different values: Table 6.28(a) and 6.28(b). Why the difference, when should which table be used? It can make a big difference in price when big building is involved with 800A circuit breakers.

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    Quote Originally Posted by PC Bester View Post
    In SANS 10142-1:2020, there are 2 tables with same description but different values: Table 6.28(a) and 6.28(b). Why the difference, when should which table be used? It can make a big difference in price when big building is involved with 800A circuit breakers.
    There is a difference in table description as can be seen from the headings pasted below from SANS
    The explanation and calculations for Table 6.28(b) precedes the table
    The clause below extracted from SANS sums up the difference between the 2 tables

    For most general purpose circuit breakers it would suffice to use
    10 multiply by the rated nominal current In for the instantaneous
    tripping point of the circuit breaker, however the precise number could
    be obtained from the manufacturer's information or from the
    instantaneous current setting of adjustable circuit breakers, thus
    Im=In x 10


    Table 6.28(a) — Minimum size and maximum length of copper earth continuity conductors rated at phase conductor
    diameter, for general purpose circuit-breaker

    Table 6.28(b) — Minimum size and maximum length of copper earth
    contuinity conductors rated at 50 % of phase conductor diameter, for
    general purpose circuit-breakers with instantaneous tripping current
    Im = 10 × In

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    Tnx very much, that gives me more clarity. I appreciate.

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