SECTION 16425
SWITCHBOARD
PART 1 GENERAL
1.01
A.
SUMMARY
Related Section:
1.
1.02
16450 - Grounding.
SUBMITTALS
A.
Submit manufacturer's literature and technical data before
starting work.
B.
Submit Shop Drawings for switchboard:
1.
2.
3.
C.
1.03
A.
Include dimensioned outline drawings, front elevation
with location and identification of devices and
instruments, bus duct connection details, conduit
entrance locations, mounting and leveling instructions,
device
ratings
and
characteristics,
main
bus
construction and location, main device key interlock
details, ground fault connection diagram, and other
details of construction.
Submit time-current coordination curves of main tie and
feeder devices.
Include details of the service bus ducts, including
dimensioned outline drawings, ratings, and installation
details.
Submit nameplate schedule for review.
QUALITY ASSURANCE
Regulatory Requirement: 1987 NEC - Article 384.
PART 2 PRODUCTS
2.01
A.
MANUFACTURERS
Bus Ducts:
1.
Westinghouse Pow-R-Way.
Project Name
Project No.
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2.
3.
4.
2.02
Challenger Electrical Equipment Corp.
Siemens.
Square D.
INSTALLATION
A.
Furnish and install where indicated a dead front type,
completely metal enclosed, self-supporting structure
independent of wall supports, consisting of the required
number of vertical sections bolted together to form one
rigid switchboard 90-3/8" high. The sides and rear shall be
covered with removable screw-on plates. Edges of front
covers or hinged front panels shall be formed. Voltage
rating shall be as indicated on the drawings.
B.
Equipment shall comply with the latest applicable standards
of NEMA, ANSI, and UL. The switchboard shall be labeled for
service entrance equipment.
C.
Small wiring, necessary fuse blocks, and terminal blocks
within the switchboard shall be furnished as required.
Groups of control wires leaving the switchboard shall be
provided with terminal blocks with suitable numbering
strips.
D.
Switchboard shall be provided with adequate lifting means
and shall be capable of being rolled or moved into
installation position and bolted directly to the floor
without the use of floor sills.
E.
Exterior and interior steel surfaces of the switchboard
shall be properly cleaned and finished with gray enamel
over a rust-inhibiting phosphatic coating. Color shall be
ANSI 61 gray.
F.
Engraved Nameplates:
1.
2.
3.
4.
Furnish for main and feeder circuits including control
fuses and for indicating lights and instruments.
Nameplates shall give item designation, circuit number,
frame ampere size, and appropriate trip rating.
Provide "Main Switch" nameplates.
Furnish
Master
Nameplate
giving
switchboard
designation, voltage, ampere rating, short circuit
rating, manufacturer's name, general order number, and
item number.
Project Name
Project No.
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16425 - 2
G.
Bus Bars:
1.
2.
3.
4.
5.
6.
7.
8.
Bus Bars shall be copper.
Bus work shall be rated to withstand maximum short
circuit stresses when connected to a supply system
having fault capacity as determined by the short
circuit study on the electrical system in the worst
contingency of _____ amps symmetrical at rated voltage.
Main horizontal bus bars shall be mounted with all
three phases arranged in the same vertical plane.
Provide full capacity neutral where a neutral is
indicated on the drawings.
A ground bus and lug shall be furnished firmly secured
to each vertical section structure and shall extend the
entire length of the switchboard.
Provide ground lugs for each overcurrent device in the
switchboard.
Hardware used on conductors shall be high-tensile
strength and zinc plated.
Terminals shall be of the anti-turn solderless type
suitable for CU or AL cable of sizes indicated.
H.
Furnish cable pull sections or top cable pull boxes where
shown on the drawings complete with cable tie down
supports. Where cable pull section or pull boxes contain
utility service cables provide utility acceptable sealing
means.
I.
Where spaces are indicated on the drawings, provide fully
bussed sections ready to receive circuit breakers.
J.
Switchboard Type (Front-Accessible Panel-Mounted):
1.
2.
Switchboards shown mounted against a wall shall be of
construction equal to Westinghouse WF or accepted
equivalent. All sections of the switchboard shall be 20
inches deep except deeper service sections containing
large ampacity main disconnects. Sections of the
switchboard shall align so the back of the complete
structure may be placed flush against a wall.
Construction shall allow maintenance of incoming line
terminations, main device connections, and main bus
bolted connections to be performed without rear access.
The feeder or branch devices shall be removable from
the front and shall be panel mounted with the necessary
device line and load connection front accessible.
Project Name
Project No.
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16425 - 3
K.
Overcurrent Protective Devices:
1.
Main Circuit Breakers:
a. Main
protective
devices
shall
be
encased
Westinghouse Systems Pow-R-Breakers, Type SPB or
accepted equivalent.
1)
2)
Breakers shall be UL listed for application in
their intended enclosure for 100 percent of
their continuous ampere rating.
Frame ampere ratings shall be as shown on the
drawings. Breakers shall have an interrupting
capacity as determined by the short circuit
study on the electrical system in the worst
contingency and shall be rated ____ ka RMS
symmetrical interrupting capacity at rated
voltage and ____ RMS symmetrical short time
rating as indicated.
b. Provide plug-in Pow-R Trip 7 trip devices that are
interchangeable between compatible breaker frames.
1)
2)
3)
4)
5)
Suitable interlocking shall be provided between
Pow-R Trip 7 trip devices and related frames to
ensure correct application.
The continuous ampere rating of the breaker
shall be determined by the insertion of an
interchangeable rating plug that matches the
load and cable requirements.
The rating plug shall be interlocked with the
tripping mechanism to automatically "open" the
breaker when the plug is removed.
The breaker shall remain "trip free" with the
plug removed.
Rating plugs shall be keyed to prevent
incorrect application between different frame
ratings.
c. Complete system selective coordination shall be
provided by the addition of the following time/
current curve shaping adjustments:
1)
2)
3)
Project Name
Project No.
Ampere Setting.
Long Time Delay.
Short Time Pick-Up (Only Mains) (Only Tie)
(Only Feeders).
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4)
5)
6)
Short Time Delay.
Ground Fault Pick-Up, if applicable per NEC .
Ground Fault Time Delay, if applicable per NEC.
d. Ground Fault Trip, when required by NEC:
1)
2)
3)
4)
5)
Provide as an integral part of the breaker.
The ground fault pickup shall be adjustable
with a maximum setting of 1200 amps according
to the NEC.
The time delay shall be adjustable in three
discrete bands for maximum system selective
coordination.
A memory circuit shall be provided to
compensate for the erratic nature of arcing
ground faults to provide for positive tripping
actions.
A residual scheme shall be used as standard for
detecting ground fault currents.
e. A separately mounted test panel shall be provided
for use with Pow-R Trip 7 trip devices. The test
panel shall test the ground fault circuit in one of
two methods.
1)
2)
2.
By tripping the breaker.
By not tripping the breaker.
Feeder Circuit Breakers:
a. Main and Feeder Protective Devices: Molded case air
circuit breakers, built, tested, and UL labeled
according to UL 489.
b. Breakers 100 through 400 amperes: Frame shall be
thermal-magnetic trip with inverse time current
characteristics.
c. Breakers
225
through
400
amperes:
Provide
continuously
adjustable
magnetic
pickups
of
approximately five to ten times trip rating.
d. Breakers 600 amperes frame and above: With solidstate
trip
complete
with
built
in
current
transformers, solid-state trip unit, and flush
transfer shunt trip, by Westinghouse Seltronic or
accepted equivalent.
1)
Project Name
Project No.
Breakers shall have easily changed trip rating
plugs with trip ratings as indicated on
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2)
3)
4)
5)
6)
drawings.
Rating plugs shall be interlocked so they are
not interchangeable between frames. When
interlocked, the breaker cannot be latched with
rating plug removed.
Breaker shall have built-in test points for
testing long delay and instantaneous and ground
fault, where shown, functions of the breaker by
means of a 120 volt operated test kit.
Provide one test kit capable of testing
breakers 600 amperes and above.
Solid-state instantaneous element shall be
continuously adjustable from approximately 4 to
8 times the trip rating, with short time
adjustment from instantaneous to 10 cycle delay
for coordination purposes.
Provide short delay override feature providing
for instantaneous tripping on high magnitude
faults.
e. Where indicated on Drawings, provide optional
adjustable trip rating plug approximately 70 to 100
percent of trip rating. Molded case breakers shall
be determined by the short circuit study on the
electrical system in the worst contingency and have
a minimum _____ ka symmetrical RMS interrupting
capacity at rated voltage.
L.
Meters:
1.
2.
250 degrees, 7.1 inch scale, rectangular front
connected switchboard type with accuracy of +1 percent
shielded.
Provide following customer metering equipment:
a. Three single pole fuse blocks with current limiting
fuses.
b. One voltmeter phase selector switch, sevenposition.
c. One voltmeter, 0-system volts.
d. One ammeter phase selector switch, four-position.
e. One ammeter, scale as indicated.
M.
Service Bus Ducts:
1.
Service bus ducts shall be in a steel housing, with
individual bus bars insulated and supported over their
Project Name
Project No.
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16425 - 6
2.
3.
N.
entire lengths. Bars shall be copper silver plated at
joints with at least 2 bolts per joint. Joint clamping
bolts shall be "cold" and accessible for tightening at
all times.
Vault stubs shall be constructed according to utility
company standards. Coordinate location of stubs into
vault with utility company.
Bus duct rating shall be of voltage and amperage as
indicated, three-phase, four-wire. The bus duct rating
shall be determined by the short circuit study on the
electrical system in the worst contingency and shall be
braced for the maximum available fault, in symmetrical
amperes.
Provide lightning and surge protection.
PART 3 EXECUTION
3.01
A.
3.02
INSPECTION
Do not proceed with the work of this section until
conditions detrimental to the proper and timely completion
of the work have been corrected in an acceptable manner.
INSTALLATION
A.
Provide adequate and safe storage space for the switchboard
when received from the factory. Follow handling and storage
instructions provided by the manufacturer. Store in a
clean, dry place while awaiting installation.
B.
Refer to the installation drawings furnished by the
manufacturer to coordinate alignment and connection of
service bus ducts and locations of conduit entry. Conduits
shown on the floor slab and turning up under the bottom of
the switchboard are not to be installed until final
approved Shop Drawings are received, in order to coordinate
conduit locations with openings in the bottom of the
switchboard. This also applies to grounding cable turning
up into the bottom of the switchboard.
C.
Steel conduits turning up under the bottom of the
switchboard shall each be provided with a steel grounding
bushing, connected to the switchboard ground bus with a
stranded copper conductor sized according to Table 250-95
of the NEC. This shall also apply to steel conduits
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entering the switchboard from the top. Non-metallic duct
entering the switchboard from the bottom shall each contain
a stranded, THW copper bonding conductor, sized according
to Table 250-95 of the NEC that shall be connected to the
switchboard ground bus. Connections of bond wires to the
switchboard ground bus shall be made with bolted
compression lugs.
D.
The metal frame of the switchboard shall be connected to
the switchboard ground bus, in at least 2 places, with
stranded copper conductors of minimum 3/0 size.
E.
The switchboard
concrete pad.
F.
Each device in the switchboard shall have a black and white
laminated plastic nameplate, of dimensions and wording as
shown on the drawings.
G.
After the switchboard is completely installed, but before
energizing, the floor under the switchboard and the floor
throughout the main switchgear room, shall be thoroughly
cleaned. Remove dust, dirt, and debris. Thoroughly clean
outside of switchboard including the top. Any factory paint
damaged before, during, or after installation shall be
repainted or touched up with same type and color paint.
H.
Service bus ducts shall be installed from the utility
company vault, through the wall and turn down into the top
of the switchboard as detailed on drawings. Provide fire
stop on each side of the wall around each bus duct. Provide
careful alignment of the bus bars of the bus duct with the
main bus of the switchboard. Insure the metal enclosure of
each service bus duct is bonded to the metal enclosure of
the switchboard. Fully coordinate, with utility company,
proper phasing of bus bars in switchboard to comply with
the NEC.
3.03
A.
shall
be
installed
on
a
4
inch
high
FIELD QUALITY CONTROL
Manufacturer's Field Service: A minimum of 1 day of
manufacturer's factory engineering service shall be
provided to lend technical assistance in setting circuit
breaker trip settings. These settings shall include but not
be limited to:
1.
Ground Fault Setting
Project Name
Project No.
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16425 - 8
2.
Long Time Trip
END OF SECTION
Project Name
Project No.
M-DCPS MASTER
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March 03
16425 - 9