System grounding to main pipe

[Toros]

Hi,
I am installing a 1200A, 3-phase commercical service.
using already provided UFFER for secodary grounding
and needed to know what size copper wire goes from service main grounding bar to main suppling cold water pipe whitin 5' of entery to the building

 

[don_resqcapt19]

See the rules in 250.66.