18-4 |  Table Reference Cable 

 This sizing of protective conductor is apply upon phase conductor size in (mm²)

Phase Conductor          |    Protective conductor (E)       |    Example                                                                  ____________

      <16.0 mm²                    Same or 1:1                                    When RYBN is 10.0 mm² then E shall be 10 mm²

      16 ~ 35 mm²                  Fixed 16mm²                                When RYBN is 30.0 mm² then E shall be 16 mm²

      > 35.0 mm²                    1/2 size                                          When RYBN is 75.0 mm² then E shall be 35 mm²

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1.      IEE  WIRING REGULATION   (16 Ed) Table 4D1A and 4D1B       [  pdf ]   

2.      Table Ca, Cg, Ci   [ pdf ]