Except as elsewhere required or permitted by this standard, live parts of electric equipment operating at 50 volts or more shall be guarded against accidentalcontact by use of approved cabinets or other forms of approved enclosures or by any of the following means:
By location in a room, vault, or similar enclosure that is accessible only to qualified persons;
By suitable permanent, substantial partitions or screens so arranged so that only qualified persons will have access to the space within reach of the live parts. Any openings in such partitions or screens shall be so sized and located that persons are not likely to come into accidental contact with the live parts or to bring conducting objects into contact with them;
By placement on a suitable balcony, gallery, or platform so elevated and otherwise located as to prevent access by unqualified persons; or
By elevation of 2.44 m (8.0 ft) or more above the floor or other working surface.
Entrances to rooms and other guarded locations containing exposed live parts shall be marked with conspicuous warning signs forbidding unqualified persons to enter.
In locations where electric equipment is likely to be exposed to physical damage, enclosures or guards shall be so arranged and of such strength as to prevent such damage.