Section 114.097. Separation of grounding conductors.

  [NESC 097C, p. 32] (Changes)

(1) Change paragraph C to read:

C. Primary and secondary circuits utilizing a single conductor as a common neutral shall have at least nine ground connections on such conductor in each 1.6 km (1 mi) of line, including those grounds at transformer locations, but not including ground connections at customers' service equipment.

(2) Change paragraph D to read:

D. Multi-grounded systems

On multi-grounded systems, the primary and secondary neutrals shall be interconnected according to Rule 097B.

Exception: Where it is necessary to separate the neutrals, interconnection of the neutrals shall be made through an electronic switching device designed for the purpose and of a type acceptable to the authority having jurisdiction. The device shall have a 60 Hz breakdown voltage not exceeding 3 kV and have a short circuit current withstand capability greater than the short circuit current available at the location of installation. At least one other grounding connection on the secondary neutral shall be provided in addition to the customer's grounds at each service entrance. A distance of not less than 3.60 m (12 ft) nor more than 6.1 m (20 ft.) shall separate the secondary neutral grounding electrode from the primary neutral and surge arrester grounding electrode, which shall not be relocated to accommodate this separation. Since a difference of potential will exist where primary and secondary neutrals are not directly interconnected, the primary and secondary grounding conductors shall be insulated for 600 V.

CR 07-021 : cr. Register January 2008 No. 625 , eff. 2-1-08; CR 13-039 : r. and recr. Register June 2014 No. 702 , eff. 7-1-14.

Note

Cooperation of all communications and supply utilities, customers of these utilities, and others may be necessary to obtain effective isolation between primary and secondary neutrals. Microsoft Windows NT 6.1.7601 Service Pack 1