(a)(1) Couplers that are used in medium- or high-voltage power
circuits shall be of the three-phase type and enclosed in a full metallic
shell, except that the Secretary may permit, under such guidelines as he may
prescribe, no less effective couplers constructed of materials other than
(2) Cable couplers shall be adequate for the intended
current and voltage.
(3) Cable couplers with any metal exposed shall be
grounded to the ground conductor in the cable.
(4) Couplers shall be constructed to cause the ground
check continuity conductor to break first and the ground conductor last when
being uncoupled when pilot check circuits are used.
(b) Cable connection boxes shall be of substantial construction and
designed to guard all energized parts from personal contact.