If observation doesn't provide you with a definate answer, then try comparing Ze to P-N external loop, if they are the same, then there is a good chance of TN-C-S ,or you could just phone up and ask the suppier, and they will pull one out of a hat for you
craig. have a look at the suppliers main fuse. If it has PME written on it and the main earth cable goes into the actual cut out on the right then that would normally be TN-C-S. You won't be able to get at the terminal without breaking the seal though.
If you can see that the main earth cable goes to an external connection next to the cut out, or is connected to the cable sheath below the cut out, then that would imply TN-S.
You need to test or enquire to confirm though.
From your previous postings you are using building control? So they, or their agent will sort the paperwork for you I would imagine.
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