[mohamed sleem]

Dear Mr. Ghali,

First off, i should thank you for the elaborated reply, basically i’m responsible to do the building design & cannot get such deep information before the actual operation, of course during the design we can estimate the percentage of the harmonics at the feeder or circuit, so if you are in my place where making the design, what is the ideal steps when sizing the grounding conductor? most of the designers always sizing the grounding conductor to half of the phase which is completly uneconomical, at the same time we don’t want to loose the protection by anyway because of some extra cost.

[mohamed sleem]

If we are doing TN-C-S system and the cable protection is a breaker, would the 1x300m2 be acceptable with a feeder 8 sets of (4x1c 630mm2)? & if all of the sets installed in group the 8x1c300m2 will be ok?

Thank you,

[mohamed sleem]

I’m not sure we can say US uses either TN-C-S or TN-C since the main panel after transformer or generator is connected directly to the earthing through the GEC (grounding electrode conductor).

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