Diskusjon:IT-nett

Skissebeskrivelse

• L1 = Faseleder 1 - Fargekode: Svart
• L2 = Faseleder 2 - Fargekode: Hvit
• L3 = Faseleder 3 - Fargekode: Brun
• PE = Jordleder (Protective Earth) eller «beskyttelsesleder» på fagspråket. Fargekode: Gul og grønn
• Consumer = Forbruker av elektrisiteten. (Bolig, industri, skole etc.)

Endret eksterne lenker

Jeg har nettopp endret 1 ekstern(e) lenke(r) i artikkelen IT-nett. Sjekk gjerne at endringen min er OK. Hvis du ønsker at jeg skal ignorere disse lenkene eller hele siden, eller hvis du har andre spørsmål, se denne spørsmålssiden. Jeg har gjort følgende endringer:

• La til arkivet https://web.archive.org/web/20160804080340/http://www.sintef.no/contentassets/8f3be4a5285b4a7a85a2987a9d397615/rapporter/1.6_seljeseth_helge---hva-er-egentlig-virkelig-smarte-energimalere.pdf til https://www.sintef.no/contentassets/8f3be4a5285b4a7a85a2987a9d397615/rapporter/1.6_seljeseth_helge---hva-er-egentlig-virkelig-smarte-energimalere.pdf

Med hilsen—InternetArchiveBot (Rapporter feil) 20. feb. 2021 kl. 12:06 (CET)

"fransk: Isolée Terre"

Please forgive me for writing in English, it's the only language I know.

I've done a lot of editing of electrical system articles on the English wikipedia, and I've done a lot of work on earthing system diagrams that appear on multiple language wikis. Discussion of one of my diagrams led me to reviewing the content of this article (with the help of Google Translate). One of the biggest problems with this article was that it was describing what an IT system is in terms of how Norway implements it, and without making it clear that this was a Norwegian specific description. Since this is an encyclopaedia, the article should really describe what an IT system is per international definition, and then can go into discussion of Norwegian specific implementation choices (and other regional specific choices if desired). I have made some changes to the article introduction (with the help of Google Translate) to help fix this. Note that, per IEC 60364-1, the key detail of an IT system is that the transformer has either no connection to Earth at all, or one with a high-impedance. Furthermore when the transformer secondary has a star-configuration, distribution of the neutral is optional in an IT system. It is important that readers of the article understand that conceptually an IT system can have a distributed neutral, and the fact that in Norway such systems don't is a choice made by Norwegian network designers.

Putting that to one side, one small change I made to the article was to remove the false indication that 'IT' comes from the French Isolée Terre. This has twice been reverted by @1000mm, so I need to raise discussion about it here. The revert was based upon the fact that an existing reference includes the text "Isolée Terre (IT) and Terra Neutral (TN) grids in Norway". This reference is a journal entry by someone called Martin Lillebo from the 21st of June 2019. The original link didn't work for me, but I was able to access a copy at .

It is common to find this suggestion that 'IT' derives from Isolée Terre, but I assert that this is false.

The authoritative source for what these letters stand for is international standard IEC 60364-1. It's an expensive document to obtain, so I don't have the latest copy, but I have access to an old copy from 2001. The text of this standard is written in both English and French. It is indisputable that the individual letters of earthing system acronyms must derive from French, since the 'T' can only derive from the French word terre, not the English earth. However, the definition of 'I' is as follows: "all live parts isolated from earth, or one point connected to earth through an impedance." (French: "soit isolation de toutes les parties actives par rapport à la terre, soit liason d'un point avec la terre à travers une impédance.").

As described, the key detail of an IT system, as I previously stated, is the transformer (or generator) either having no connection to earth, or a connection through a high impedance, and with exposed-conductive-parts of installations being connected directly to Earth. If you look at the French definition of 'I', the two key words are isolation and impédance. Since a choice has to be made between isolation and impedance by network designers, both words must have equal importance. Both words also start with the letter 'I'. Thus it should be logically concluded that 'I' relates to both isolation and impedance together, and thus whoever it was who, at some point in the past, associated 'IT' with Isolée Terre, made a big mistake.

It should be noted that such terms like terre terre, terre neutre, and isolée terre do not appear in the international standard, nor in the IEC 60050 standard which defines official international electrotechnical vocabulary. I know of no authoritative (IEC) documents that would support the idea that IT derives from isolée terre, and I don't know where this seemingly false idea came from.

The fact of one or more random individuals or organisations in the industry using such terms does not make them correct, or more specifically does not mean that it is a fact that the 'I' in IT derives from 'isolation' alone.

This suggestion in the text should thus be removed, or corrected to 'fransk: Isolée eller Impédance Terre'. DiscreetParrot (diskusjon) 14. feb. 2026 kl. 22:21 (CET)

You are correct, upon further investigation it is not French: Isolée Terre, but in fact Latin: Isolation Terra. Just as a TT grid is Terra Terra. ///Mvh. 1000mm (diskusjon) 14. feb. 2026 kl. 23:15 (CET)

Sigh. According to what authoritative sources? I feel it's highly unlikely that the IEC will have documented somewhere that they specifically derived the system letters from Latin words for earth/neutral/isolation/impedance/combined/separate. It makes more sense that they derived them from French. I also seem to recall previously reading past discussion in the English wikipedia that disproved the idea that they were Latin derived.

Regardless of which language exactly they had in mind though, where is the IEC source proving that 'I' was derived only from 'isolation' and not also 'impedance'?! DiscreetParrot (diskusjon) 15. feb. 2026 kl. 00:54 (CET)

Then what language would «Terra» be? ///Mvh. 1000mm (diskusjon) 15. feb. 2026 kl. 01:12 (CET)

Terra is of course Latin, while terre is French. But it is the IEC that came up with these earthing system acronyms, and they did not say from which language the letters were derived. They simply provided French and English definitions for what each letter in the system acronyms represents. It is from these definitions that we can guess what specific word or words each letter was derived from. It is clear from 'T' that we can rule out the possibility that they derived from English words. It is reasonable therefore to conclude that they were derived from words used in the French definitions. I don't believe that there's any reliable evidence to support the idea that the IEC actually had Latin in mind. Please point to an IEC source that even uses the word 'Terra'.

Whether it's French or Latin though is besides the point. DiscreetParrot (diskusjon) 16. feb. 2026 kl. 18:59 (CET)

See referense number 3, including the quote: «IT (Isolation Terra): Isolation Terra earthing as defined in IEC 60364». ///Mvh. 1000mm (diskusjon) 16. feb. 2026 kl. 19:02 (CET)

For the benefit of future readers, reference number 3 currently points to a copy of ETSI EN 203 408 v1.1.1.

This European standards document indeed contains a definition stating "IT (Isolation Terra): Isolation Terra earthing as defined in IEC 60364-1 [i.8]".

However, let's take a closer look...

• On the very next page there's a definition of "TNS: AC distribution earthing arrangements as defined in IEC 60364-1 [i.8] where earthing and neutral wires are separated". This mistakenly uses a non-standard acronym of 'TNS' rather than 'TN-S', and the description is rather imperfect.
• Going back to its definition of 'IT', there's a prominent note, somewhat poorly written, relating the definition to "HRMG in ETSI EN 301 605". Looking at this other standards document - it includes a definition for "IT, TN-C, TN-S, and TT systems (see IEC 60364-1 [2])" which quotes (with minor differences) the actual definitions of the letters from IEC 60364-1. ('HRMG' apparently means 'High Resistance Middle point Grounding' per the first document, but I couldn't find a use of this in the second).
• Towards the end of the document they seem to have made use of wire-colour images taken from wikipedia, seemingly without any attribution, which goes against their license, and in some cases, for colour variations that presumably weren't available at the time, they've used some very crude imitations.

This wouldn't be the first time I've found problems with standards documents. They're not always of quite the level of high quality material as you'd expect, though of course they are generally one of the best sources we have for certain information.

In this case I think that the author(s) of this particular document have done somewhat sloppy work in places and the presence of the text "IT (Isolation Terra)" holds absolutely no authoritative value. I think they've just seen such text used on wikipedia and elsewhere on the web and just stupidly copied it.

So I'm sorry, but this holds no real value at all in supporting the idea that Latin is correct rather than French, or that the 'I' in 'IT' relates only to the word isolation rather than also impedance. DiscreetParrot (diskusjon) 16. feb. 2026 kl. 20:24 (CET)