2.7.4
Components
cables as shown on the drawings. The circuit breakers shall be
individually stationary mounted, as shown on the drawings, and shall be
operable and removable from the front. Where shown on the drawings,
circuit breakers shall be enclosed in individual compartments. [The
an integrated assembly on the switchboard and shall conform to the
applicable requirements of paragraph PANELBOARDS.]
2.8
PANELBOARDS
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NOTE: The short-circuit current rating assigned to
the panelboard shall be in accordance with NEMA PB 1.
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Panelboards shall consist of assemblies of molded-case circuit breakers
with buses and terminal lugs for the control and protection of branch
circuits to motors, heating devices and other equipment operating at 480
volts ac or less. Panelboards shall be UL 67 labeled. "Loadcenter" type
panels are not acceptable. Panelboards shall be designed for installation
in surface-mounted or flush-mounted cabinets accessible from the front
only, as shown on the drawings. Panelboards shall be fully rated for a
short-circuit current of [14,000] [22,000] [_____] symmetrical amperes RMS
ac.
2.8.1
Enclosure
Enclosures shall meet the requirements of UL 50. All cabinets shall be
fabricated from sheet steel of not less than 3.5 mm No 10 gage if
flush-mounted or mounted outdoors, and not less than 2.7 mm No 12 gage if
surface-mounted indoors, with full seam-welded box ends. Cabinets mounted
outdoors or flush-mounted shall be hot-dipped galvanized after fabrication.
Cabinets shall be painted in accordance with paragraph PAINTING. Outdoor
cabinets shall be of NEMA 3R raintight and [conduit hubs welded to the
cabinet] [a removable steel plate 6 mm 1/4 inch thick in the bottom for
field drilling for conduit connections.] Front edges of cabinets shall be
form-flanged or fitted with structural shapes welded or riveted to the
sheet steel, for supporting the panelboard front. All cabinets shall be so
fabricated that no part of any surface on the finished cabinet shall
deviate from a true plane by more than 3 mm 1/8 inch. Holes shall be
provided in the back of indoor surface-mounted cabinets, with outside
spacers and inside stiffeners, for mounting the cabinets with a 13 mm 1/2
inch clear space between the back of the cabinet and the wall surface.
Flush doors shall be mounted on hinges that expose only the hinge roll to
view when the door is closed. Each door shall be fitted with a combined
catch and lock, except that doors over 600 mm 24 inches long shall be
provided with a three-point latch having a knob with a T-handle, and a
cylinder lock. Two keys shall be provided with each lock, and all locks
shall be keyed alike. Finished-head cap screws shall be provided for
mounting the panelboard fronts on the cabinets. Enclosure shall have
nameplates in accordance with paragraph NAMEPLATES. Directory holders,
containing a neatly typed or printed directory under a transparent cover,
shall be provided on the inside of panelboard doors.
SECTION 16403A
Page 32