110.27 Guarding of Live Parts.
(A) Live Parts Guarded Against Accidental Contact.
Except as elsewhere required or permitted by this Code,
live parts of electrical equipment operating at 50 volts or
more shall be guarded against accidental contact by approved
enclosures or by any of the following means:
(1) By location in a room, vault, or similar enclosure that is
accessible only to qualified persons.
(2) By suitable permanent, substantial partitions or screens
arranged so that only qualified persons have access to
the space within reach of the live parts. Any openings
in such partitions or screens shall be sized and located
so that persons are not likely to come into accidental
contact with the live parts or to bring conducting objects
into contact with them.
(3) By location on a suitable balcony, gallery, or platform
elevated and arranged so as to exclude unqualified
persons.
(4) By elevation above the floor or other working surface
as shown in 110.27(A)(4)(a) or (b) below:
a. A minimum of 2.5 m (8 ft) for 50 to 300 volts
b. A minimum of 2.6 m (81⁄2 ft) for 301 to 600 volts
(B) Prevent Physical Damage. In locations where electrical
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.
(C) Warning Signs. Entrances to rooms and other guarded
locations that contain exposed live parts shall be marked
with conspicuous warning signs forbidding unqualified persons
to enter. The marking shall meet the requirements in
110.21(B).
Informational Note: For motors, see 430.232 and 430.233.
For over 600 volts, see 110.34.
