110.26(E) Dedicated Equipment Space. All switchboards, switchgear,
panelboards, and motor control centers shall be located in
dedicated spaces and protected from damage.
Exception: Control equipment that by its very nature or because of other
rules of the Code must be adjacent to or within sight of its operating
machinery shall be permitted in those locations.
(1) Indoor. Indoor installations shall comply with 110.26(E)
(1)(a) through (E)(1)(d).
(a) Dedicated Electrical Space. The space equal to the width
and depth of the equipment and extending from the floor to a
height of 1.8 m (6 ft) above the equipment or to the structural
ceiling, whichever is lower, shall be dedicated to the electrical
installation. No piping, ducts, leak protection apparatus, or
other equipment foreign to the electrical installation shall be
located in this zone.
Exception: Suspended ceilings with removable panels shall be permitted
within the 1.8-m (6-ft) zone.
(b) Foreign Systems. The area above the dedicated space
required by 110.26(E)(1)(a) shall be permitted to contain
foreign systems, provided protection is installed to avoid
damage to the electrical equipment from condensation, leaks,
or breaks in such foreign systems.
(c) Sprinkler Protection. Sprinkler protection shall be
permitted for the dedicated space where the piping complies
with this section.
(d) Suspended Ceilings. A dropped, suspended, or similar
ceiling that does not add strength to the building structure
shall not be considered a structural ceiling.