"Dave Liquorice" wrote in message
. 1...

And 6mm from the gridswitch to the sockets? If you've dropped to
2.5mm from the gridswitch to socket that section is not properly
protected by the 32A breaker...

Wrong. 2.5mm^2 will usually be fine for the socket runs. Overload
protection is provided by the plug-top fuses, s/c fault protection by the
fuse or MCB in the consumer unit. Strictly speaking the designer should
check that disconnection time and cable thermal protection requirements are
met, but, with MCB protection and normal circuit lengths of a few metres
from the split, there won't be a problem. This combination of device rating
and cable size is no different to that of the unfused spur taken from a 32 A
ring circuit.

In fact 1.5mm^2 would probably be OK for the socket runs in most cases, but
would certainly need to be checked by calculation. Sticking to the
conventional 2.5mm^2 gives a degree of belt'n'braces safety.

--
Andy