2.6.1.6
NEMA 3R Enclosures
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NOTE: Enclosures covered by this specification are
not intended to be non walk-in type. Walk-in
front-aisle, walk-in common aisle and walk through
common aisle styles are available, and where
required should be specified. The latter styles of
enclosures shall comply with NFPA 101 for means of
egress and lighting.
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The motor control center shall be non-walk in NEMA Type 3R rainproof
enclosure as shown on the drawings. The outside enclosure shall consist of
smooth select steel sheets on a structural steel frame. Full-length single
or double doors shall be provided with top and bottom bolts and a center
latch operated by means of a keyed handle. Steel sheets and doors shall be
not less than 3.5 mm No. 10 gage thick and doors shall have bent angle or
channel edges with all corner seams welded and ground smooth. The motor
control center within the enclosure shall be assembled with adequate
gaskets and structure to assure a measure of vandal resistance.
Ventilating openings and an effective insulating air space of approximately
50 mm 2 inches shall be provided below the roof of the structure which
shall slope from front to back for adequate drainage. The outside edges of
the control center base shall permit easy sealing at the concrete surface
with mastic compound. A 200-watt outdoor lighting fixture with globe and
guard shall be furnished to light the front of the assembly. All lighting
connections shall be watertight. A weatherproof switch installation shall
be furnished on the front or side of the enclosure so that the light can be
switched prior to opening the assembly doors. The exterior manual switch
shall be "ac" rated, 15 amperes, 120/277 volts. Two duplex receptacle
units shall be provided within the outer weatherproof enclosure. The
lighting fixture and receptacles shall be wired to the 120-volt ac
panelboard located in the control center, and external wiring shall be run
in rigid galvanized steel conduit.
2.6.1.7
Shutters
Drawout units shall have shutters which close when the unit is withdrawn to
isolate the vertical bus.
2.6.1.8
[Thermostatically Controlled Strip Heaters
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NOTE: Delete this paragraph when not required.
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Thermostatically controlled strip heaters as specified in paragraph SPACE
HEATERS shall be provided [in all motor control centers] [where indicated].]
2.6.2
Buses
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NOTES: When either copper of aluminum bus are
allowed the manufacturers will generally provide the
less expensive aluminum. Use ASTM 317 when aluminum
bus is permitted.
NEMA ICS 2 allows a 65 degrees Celsius temperature
SECTION 16403A
Page 20
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