TN-S Power System

Dear Sir / Lady
I requested to answer my question that when we have TN-S power system in an industrial plant (As per figure 31A - TN-S system of part No.312.2.1 of IEC60364-3 standard in below page), and have earthing system which is included some earthing rod and kilometers buried copper conductors that embedded in earth (Abut 80 cm deep in earth) and all the equipments earting point such as body of electrometers and transformers , all kind of electrical panels earthing bus and etc have been connected to above mentioned earthing network via yellow green PVC covered copper conductors , so weather can we assumed that the earthing net is part of protective conductors (PE) , for example in a 400 Volt system to feeding a 3 phase electromotor , need or no need to use 3×240+120 〖mm〗^2 ( 120 〖mm〗^2 core is yellow green ) or 3×240 〖mm〗^2 with separate 1 core yellow green directly connected to buried earthing network, eventually I ask to give the address (Page and Paragraph ) of IEC ,IEEE,DIN(VDE) or NFPA or other standards .
Best regards
H. Eftekharzadeh

Asked Jul 15, 2013

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