Live electrical equipment operating at 50 volts or more must be guarded against accidental contact in one of four ways: by enclosing it in a room, vault, or similar enclosure accessible only to qualified persons; by placing it behind permanent, substantial partitions or screens that only qualified persons can access; by placing it on an elevated balcony, gallery, or platform that excludes unqualified persons; or by elevating it at least 2.5 meters (8 feet) above the floor or other working surface.
Live electrical equipment must be guarded against accidental contact by enclosing it in an enclosure accessible only to qualified personnel, placing it behind permanent partitions or screens that only qualified personnel can access, placing it on an elevated balcony, gallery, or platform that excludes unqualified personnel, or elevating it at least 2.5 meters (8 feet) above the floor or other working surface. Contact conductors may be left bare, but guards should be provided to prevent accidental contact with persons or objects.
(B) Prevent Physical Damage.
Enclosures or guards must be arranged and strong enough to protect electrical equipment from physical damage.
(C) Warning Signs.
Entrances to rooms and other guarded locations containing live parts must be marked with warning signs forbidding entry by unqualified persons. Motors must comply with 430.232 and 430.233, and over 600 volts must comply with 110.34.