Have a look at B3 page 43, not much chance of it being TN-S, it will be TN-C-S
http://library.ukpowernetworks.co.u...017+Customer+Installation+Earthing+Design.pdf
thats if links work
http://library.ukpowernetworks.co.u...017+Customer+Installation+Earthing+Design.pdf
thats if links work