What size conduit for 3 250 kc mil?

What size copper grounding electrode conductor is required for a service that has three sets of 600 kc mil copper conductors per phase?

The grounding conductor of a service distribution is sized by the ampacity of the service. By just stating the wire size, this does not give this information, as many variables enter into what wires are used depending on length, ambient temperature and insulation factor to name a few.