Yes, it must be clear from what I've written that I understand all that, but the crucial thing is understanding the different relevance of the first and second letters.
Interesting. As you will realise, I find it hard to agree with that, for the reasons I've explained.
That happens to be true (with a different earth rod), but my DNO-supplied-supply (and associated MET, CUs/DBs and circuits) could equally well be TN-S or TN-C-S, without affect the discussion about the 'type' of the (separate) genny-supplied system.
I suppose that must mean that you really think it is within the spirit of TN-S when the incoming separate conductor from the supply does not provide any path to earth (unless/until a consumer connects it to a path to earth) - but that surprises me. I still think that the fundamental property of any TN-x system (as compared with a TT or IT one) is that the supplier (usually the DNO), provides the earth (a path to earth) in the form of an 'earth terminal', either via their neutral or a separate conductor.
I don't think it is safer, it is fine for a single piece of current using apparatus such as your shaver socket but as you start to involve more circuits it becomes more complicated. You have to take into account multiple fault scenarios as the first fault will not be detected, double poled OCPDs etc.
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Well, yes, and that's why I initially thought of it as an IT system. What is earthed is the MET, and hence the CPCs of 'the installation' - and the only purpose the CPC from genny to MET serves is to earth the frame etc. of the genny.
Maybe not. Indeed, even if there were no rod or explicit bonding of the 'genny installation' there would still be an 'incidental' path to earth from the CPCs of the 'genny installation final circuit' via pipework and the main installation's earthing and bonding (remember that the main purpose of the genny supply was for central heating). However, if it were not for that incidental earthing of the CPCs of that final circuit (upon which one theoretically should not rely), in the absence of my rod those CPCs would be 'floating'. Although I'm struggling to think of a reason, I'm not sure I'd feel comfortable about that.
All TN-S supplies have some sort of connection with mother earth for the system at source, wether it be a rod, a tape or even a building steel structure.
In an IT system you wouldn't have the N-E link in the generator, the source is left floating (or a big resistor linking N-E), I have only ever seen an installation installed like this installed once.
It serves the purpose of tying the system to earth. Without this tie items such as RCDs will not provide supplementary shock protection
That wouldn't be a good idea without knowing exactly what you have, is the N-E link present in the generator?
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