The 2008 NEC, Article 250.24(C) states:
" Where an ac system operating at less than 1000 volts is grounded at any point, the grounded conductor(s) shall be run (i.e. from the utility point of service) to each service disconnect means and shall be connected to each disconnecting means grounded conductor(s) terminal or bus..........."
Is there any reference in the NEC to systems at, or at greater than 1000 volts requiring a grounded conductor(s) when in similar conditions as in the above article?. I have not been able to find any reference.
In is my opinion for the conditions in Article 250.24(C),the need for a low impedance path to the utility source is needed.