E3305.3 Dedicated panelboard space. The space equal to the
width and depth of the panelboard and extending from the floor
to a height of 6 feet (1829 mm) above the panelboard, or to the
structural ceiling, whichever is lower, shall be dedicated to the
electrical installation. Piping, ducts, leak protection apparatus
and other equipment foreign to the electrical installation shall
not be installed in such dedicated space. The area above the dedicated
space shall be permitted to contain foreign systems, provided
that protection is installed to avoid damage to the electrical
equipment from condensation, leaks and breaks in such foreign
systems (see Figure E3305.1).
Exception: Suspended ceilings with removable panels shall
be permitted within the 6-foot (1.8 m) dedicated space