djk,
sounds like a radial circuit design with either 2.5mm or 4.00mm twin and earth (nm) cable.
the best way is to isolate each circuit and remove the socket outlets (receptacle) and find out which one only has one cable going to it.
the rest of the installation looks quite standard (in accordance with the IEE regs),
the surge arrester is a bit of an odd one as we only fit them on commercial,
A question,
is the dis board a split load, IE one main isolator for the whole board and one RCD controlled side or,
just one isolation switch (switch disconnector) and on board RCDs ??
the make of the dis board is a good one, having fitted a couple myself over the years.
John H
