View all text of Subchapter III [§ 861 - § 878]
§ 868. Underground high-voltage distribution
(a) Circuits entering underground areas of mines; circuit breakers
(b) Circuits extending underground and supplying equipment; direct neutral grounds; ground conductors for frames, exceptions; location of disconnection devices, exceptions
(c) Grounding resistors
(d) Inclusion of fail safe ground check circuits in resistance grounded systems; operative functions; time extension
(e) Underground cables used in resistance grounded systems; metallic shields for power conductors; standards; splices
(1) Underground high-voltage cables used in resistance grounded systems shall be equipped with metallic shields around each power conductor, with one or more ground conductors having a total cross-sectional area of not less than one-half the power conductor, and with an insulated internal or external conductor not smaller than No. 8 (AWG) for the ground continuity check circuit.
(2) All such cables shall be adequate for the intended current and voltage. Splices made in such cables shall provide continuity of all components.
(f) Couplers for power circuits; guidelines for construction
(g) Connections of single-phase loads
(h) Installation of underground transmission cables
(i) Disconnection devices; location; visual observation of position of switch
(j) Circuit breakers and disconnection devices; markings
(k) Splices in cables used as trailing cables; terminations and splices in other cables
(l) Grounding of frames of underground equipment
(m) Moving of power centers, transformers, and cables; deenergizing; exceptions; safety guidelines; record of examinations
(Pub. L. 91–173, title III, § 308, Dec. 30, 1969, 83 Stat. 780.)