This section of the guide is concerned with the neutral grounding of single- and three-phase alternating current (ac) electric utility primary distribution systems with nominal voltages in the range of 2.4 kV to 34.5 kV. For the purpose of this guide, the term "distribution" includes the substation providing power to distribution feeders, the distribution feeders, and the distribution transformers providing service at utilization voltages. The scope of this guide does not include the grounding of the low-voltage secondary systems supplied by distribution transformers, or consumer-owned facilities that are covered by other standards such as the National Electrical Code (NEC) (B6)