9.7.3 The same route without interference requirements of the line, can be laid in the same metal trunking. The total cross-section (including outer sheath) of the wire or cable in the trunking shall not exceed 20% of the cross-section of the trunking, and the current-carrying conductor shall not exceed 30. I would like to ask where the current-carrying wire is a single-phase circuit in the L line, not including the N and PE line is it? That is, a distribution box leads to more than 30 single-phase circuit, its current carrying wire number is the number of circuits? Is the N-wire not a current-carrying wire? More
"The total cross-section of the wire or cable in the trunking (including the outer sheath) should not exceed 20% of the cross-section of the trunking, and the current-carrying conductor should not exceed 30" is to limit the heat of the current-carrying conductor. , Is the normal working current conductor. PE line is non-normal current conductor.
N line must belong to the current conductor. If the three-phase load balance, N-line current is . such as imbalance, there is a current through. Such as the third harmonic of the grid serious, N-line current may be greater than the phase current. At this point, the wire cross-section should be the current flow of N line selection. PE line should be non-current-carrying conductor.
Be a current-carrying conductor, unless the three-phase complete, always balanced, and no harmonics
