30 CFR § 75.705-1
Work on high-voltage lines.
(a) Section 75.705 specifically prohibits work
on energized high-voltage lines underground;
(b) No high-voltage line, either on the surface or underground, shall
be regarded as deenergized for the purpose of performing work on it, until
it has been determined by a qualified person (as provided in
§75.153) that such high-voltage line has been
deenergized and grounded. Such qualified person shall by visual observation
(1) determine that the disconnecting devices on the high-voltage circuit are
in open position and (2) ensure that each ungrounded conductor of the
high-voltage circuit upon which work is to be done is properly connected to
the system-grounding medium. In the case of resistance grounded or solid
wye-connected systems, the neutral wire is the system-grounding medium. In
the case of an ungrounded power system, either the steel armor or conduit
enclosing the system or a surface grounding field is a system grounding
medium;
(c) No work shall be performed on any high-voltage line on the
surface which is supported by any pole or structure which also supports other
high-voltage lines until: (1) All lines supported on the pole or structure
are deenergized and grounded in accordance with all of the provisions of this
section which apply to the repair of energized surface high-voltage lines; or
(2) the provisions of §§75.705-2 through 75.705-10
have been complied with, with respect to all lines, which are supported on
the pole or structure.
(d) Work may be performed on energized surface high-voltage lines
only in accordance with the provisions of §§75.705-2
through 75.705-10, inclusive.