Repost - Earth Rod not taken account in TN systems

Hi All,

I realise the function of the earth rod in a TN system is to provide a close reference to true earth for the neutral

The thing that has confused me slightly is the TNCS PNB, which has an earth rod located at the consumer end. When i looked at the old forums there was a debate between whether this was TNCS or TNS, as the neutral carries no current due to the earth rod, and therefore by definition cannot be a combined conductor. If the current is not dissipated into the ground via the rod, why would no current flow in the neutral of this system prior to the rod

Thanks in advance

EDIT: My question wasn’t phrased very well and I’ve tried to clean it up for future readers, but i think this is the correct summary.

Fault current CAN flow between the neutral/earth link and the neutral point of the transformer in a PNB earthing arrangement. The previous forum posters were essentially saying is that even though though the link is remote, fault current will still flow in the CNE cabling, but we can note that it also would in a pure TN-S system but more likely an internal section of busbar within the TX and the neutral bar, instead of external cabling and by that logic TN-S would be a form of TN-C-S if semantics were involved.

Link to thread

 What earthing arrangement is this? 

Parents
  • The reply wasn’t intended for you Graham.

  • I have been accused of using AI by Fiftyherrtz. in reference to IET documentation. I do reference online content/articles but doesn’t everyone? Just a thought, maybe AI is referring to my answers ? Slanderous accusations on the internet is a dangerous game to play.

  • Hi AMK, apologies, i did delete the reply immediately after replying, after thinking about it as i did not want to cause offence. The reason i asked was the format of the references in your post, which i have seen before generated by AI, and was genuinely curious as the information was helpful. I also saw that you submitted a post on AI recently.

  • The reply wasn’t intended for you Graham.

    No problem ... all part of a healthy debate.

    This is not a clear-cut subject, as I alluded to. You are correct that the current suite of guidance from the IET does not want to confuse the issues of 'PME vs TN-C-S vs TN-S vs PNB' and, if you do have a PNB supply (unless you have what might by some be termed as PNB from a private transformer) you should treat the supply as PME.

  • Hi AMK, apologies, i did delete the reply immediately after replying, after thinking about it as i did not want to cause offence. The reason i asked was the format of the references in your post, which i have seen before generated by AI, and was genuinely curious as the information was helpful. I also saw that you submitted a post on AI recently. Apologies, hopefully this can keep constructive even with my error

    Also remember this is a discussion forum, and not a source of free consultancy ... i.e. you need to make your own conclusions regarding the discussions here, not use them as "the answer". See Community Rules and Guidelines, especially item 6.

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  • Hi AMK, apologies, i did delete the reply immediately after replying, after thinking about it as i did not want to cause offence. The reason i asked was the format of the references in your post, which i have seen before generated by AI, and was genuinely curious as the information was helpful. I also saw that you submitted a post on AI recently. Apologies, hopefully this can keep constructive even with my error

    Also remember this is a discussion forum, and not a source of free consultancy ... i.e. you need to make your own conclusions regarding the discussions here, not use them as "the answer". See Community Rules and Guidelines, especially item 6.

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