30A fuse in CU, either 2 2.5mm cables from fuse to RCD, or 6mm (id go with 6mm if you have it). form RCD, ring as normal.
Cheers Andy
Sorry, I take it, just one 6mm cable from fuseway to RCD.
And from RCD ring as normal
Are you allowed to do two 2.5 mm cables, bit messy looking but is...