MIL-DTL-16036M(SH)
3.7 Hinged and removable enclosing panels.
3.7.1 Structure. Panels shall be made from sheet 3/32 to 1/8 inch thick of U.S. Gauge number 11 (commercial
tolerances acceptable). Panels shall be formed with bent angle or channel edges. Flanges of panels shall be welded
at the corners and ground smooth. There shall be no butt joints on the panel surfaces. Where the strength of the
paneling is materially weakened by cutouts, it shall be reinforced by stiffening members. Size of the cutout for Type
AQB and ACB circuit breaker operating handles and escutcheons shall be in accordance with MIL-DTL-17361 and
MIL-DTL-17587, respectively. Removable sheets and panels on the front and rear shall be provided with lifting
handles. Mounting and alignment devices shall be provided to facilitate installation and removal of removable
enclosing panels. Alignment pins or devices shall be staggered or have a unique arrangement in order to prevent
interchangeability of panel fronts or rears between units of the same switchboard section and units of other
switchboard sections within the same switchboard group or ship s compartment. When installed, the panels shall be
electrically grounded to the unit framework in accordance with MIL-STD-1310. Removable and hinged enclosure
access panels with mounted energized components shall be grounded to the enclosure using a flexible ground strap
when any voltage on the access panel exceeds 30 volts.
3.7.2 Panel hinging. Panels shall be hinged to provide access to electrical equipment mounted thereon. Means
shall be provided so that these hinged sections may be opened without removing the guard rail. Hinged panels shall
be provided with door stops or positioning devices to stop the door in its opening swing and to hold it in the open
position. The preferred side for hinging panels is the left-hand side when facing the front of the panel. A typical
panel hinge assembly is shown on figure 14. Hinged panels shall be electrically grounded to the unit framework by
a separate conductor. Hinges are not considered to be an acceptable grounding path.
3.8 Mounting of equipment.
3.8.1 Securing of equipment. Equipment shall be secured to the panels of framework in order to insure against
dislodgement caused by shock. Brackets and mounting lugs or feet shall have fully enclosed holes or slots. Open
end slots shall not be acceptable. Devices mounted on the unit side sheet or internal partitions shall be easily
removable from the inside of the unit. Devices mounted on the unit side sheet shall not interfere in any way with the
inner unit bolting to form switchboard sections.
3.8.2 Mounting bolts and screws. Bolts used in the assembly of the framework and for securing the large
devices to the framework shall be hexagon or hexagon socket head type. Screws for miscellaneous purposes shall be
hexagon socket head, flat, or phillips head type.
3.8.3 Arrangement of equipment. No device shall extend beyond the edges of the panel on which it is mounted.
Symmetrical arrangements of equipment on the units are desirable, but should not take precedence over
arrangements where space may be saved for future or spare equipment.
3.8.4 Polarity. For DC, when facing the front of the switchboard or panel, left-hand contacts shall be of the
same polarity (negative) and the right-hand contacts of the same polarity (positive).
3.8.5 Phase rotation. For AC, when facing the front of the switchboard or panel, the phase rotation shall be A,
B, and C, respectively, from right to left, top to bottom, or front to back.
3.8.6 Casualty power equipment.
3.8.6.1 Arrangements. For ship s service and emergency switchgear groups the casualty power circuit breaker
and casualty power terminal (required herein on the generator units) shall be available for use in the event of damage
to the remainder of the switchboard on which the generator unit is located. The lead from the generator bus on
generator units for the main bus on power distribution units to the casualty power connection and equipment shall be
as short and direct as practicable and the casualty power terminal shall be readily accessible to permit rapid
connection of the casualty power cable. Casualty power terminals and circuit breakers are required on load centers
as specified in 3.4.4.1.
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