Take a look at the 2002 NEC 250.184(D)(3) keep in mind this is for systems above 1KV.

Quote
(3)At least one grounding electrode shall be installed and connected to the multigrounded neutral circuit conductor every 400 m (1300 ft).

Steve is it possible that the 1911 NEC. Pg 25, Section 15 was referring to a multigrounded neutral system. The same system the power companies use today.

Thanks for a look into the 1911 NEC. [Linked Image]

Bob

Bob Badger
Construction & Maintenance Electrician
Massachusetts