(a) 600 volts or less. For purposes of this chapter, all electrical conductors and equipment rated at 600 volts or less, installed outside of permanent buildings in park electrical wiring systems constructed, or approved for construction, shall be listed and labeled as approved for their intended use.

(b) Greater than 600 volts. Conductors and equipment installed in systems operated at more than 600 volts shall comply with the applicable provisions contained in the California Electrical Code, Article 490, and the High Voltage Safety Orders contained in Title 8, California Code of Regulations, Chapter 4, Subchapter 5, Group 2.

(c) A grounded neutral conductor may be a bare conductor when properly isolated from phase conductors. A bare neutral conductor, or a bare concentric stranded conductor of a cable used as a grounded neutral conductor, shall be copper when installed underground. These types of systems shall be solidly grounded.