I'm looking at doing a CU change. Current main earthing and bonding conductors are both 6mm. Tails are 16mm on a 60/80 amp fuse (TNCS). ZE = 0.1 , 230v, single cable not bunched.
Looking at the regs (543.1.1) and applying the adiabatic equation (543.1.3), 6mm seems ok for main earthing...