SECTION 16435
BRANCH CIRCUIT PANELBOARDS
PART 1 - GENERAL
1.01
REQUIREMENTS
A.
1.02
SCOPE
A.
1.03
The general provisions of the Contract, including General and Supplementary
Conditions and General Requirements, apply to the work specified in this
Section.
The work covered under this Section shall include furnishing and installing circuit
breaker type branch circuit panelboards complete for all systems as shown on
the Drawings and herein specified.
QUALITY ASSURANCE
A.
All equipment, materials, and their installation shall conform to the requirements
of the National Electrical Code (NEC), local code requirements, and these
Specifications.
B.
All equipment and materials shall be listed by Underwriter's Laboratories, Inc.
(UL) for their intended use and shall bear the UL label.
C.
Equipment shall be constructed in accordance with National Electrical
Manufacturer's Association (NEMA) standards.
D.
Submittals are required in accordance with SECTION 16010 of these
Specifications. The manufacturer shall furnish, but not be limited to the
following:
1.
Circuit breaker layout with dimensions and nameplate designation.
2.
Circuit breaker trip ratings and frame sizes.
3.
Component list.
4.
Conduit entry/exit locations.
5.
Assembly ratings, including short-circuit rating, voltage, and continuous
current rating.
6.
Bus material, including ground bar.
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BRANCH CIRCUIT PANELBOARDS
1.04
SECTION 16435
7.
Cable terminal sizes.
8.
Product data for each type of panelboard.
DELIVERY, STORAGE AND HANDLING
A.
Deliver material and products in factory labeled packages. Store and handle in
strict compliance with manufacturer’s instructions and recommendations.
B.
Each panelboard section shall be delivered in individual shipping cases and
individually wrapped for protection.
C.
Store in a clean, dry space. Maintain factory protection and /or provide an
additional heavy canvas or heavy plastic cover to protect panelboards from dirt,
water, construction debris, and traffic. Where applicable, provide adequate
heating within enclosures to prevent condensation.
D.
Handle in accordance with NEMA PB1.1 and manufacturer’s written instructions.
Handle carefully to avoid damage to panelboards internal components,
enclosure and finish.
PART 2 - PRODUCTS
2.01
MANUFACTURERS
A.
2.02
The branch circuit panelboards shall be as manufactured by CUTLER-HAMMER,
GENERAL ELECTRIC, SIEMENS, or SQUARE D.
PANELBOARDS
A.
This Contractor shall furnish and install where indicated on the Drawings,
deadfront branch circuit panelboards incorporating switching and branch circuit
protective devices of the number, ratings, and type noted herein or as shown on
the Drawings. Branch circuit panelboards shall have NEMA 1 general purpose
enclosures and shall be surface or flush mounted as noted. All branch circuit
panelboards shall be rated for the intended voltage and shall be in accordance
with UL's "Standard for Panelboards" and "Standard for Cabinets and Boxes"
and shall be so labeled. Branch circuit panelboards shall also comply with
NEMA "Standard PB1 for Panelboards" and the NEC.
B.
Ratings: [ENGINEER, EDIT OUT SHORT-CKT STUDY IF NOT IN PROJECT]
1.
Panelboards rated 240 Vac or less shall have short-circuit ratings as
shown on the drawings or as determined by the Short-Circuit
Coordination Study whichever is higher, but not less than 10,00016435-2
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BRANCH CIRCUIT PANELBOARDS
SECTION 16435
amperes RMS symmetrical.
2.
Panelboards rated 480 Vac shall have short-circuit ratings as shown on
the drawings or as determined by the Short-Circuit Coordination
Study whichever is higher, but not less than 14,000-amperes RMS
symmetrical.
3.
(ENGINEER, DELETE THIS PARAGRAPH IF NOT USING SERIES
CONNECTED RATINGS) Panelboards shall have a fully rated or series
connected short-circuit rated interrupting ratings as indicated on the
drawings and shall be labeled with a UL short-circuit rating. When series
connected ratings are applied with integral or remote upstream devices, a
label shall be provided. It shall state the conditions of the UL series
connected ratings including:
a.
b.
c.
C.
Size and type of upstream device.
Branch devices that can be used.
UL series short-circuit rating.
Interiors:
1.
All interiors shall be completely factory assembled with switching and
protective devices, wire connectors, etc. All conductor connectors,
except screw terminals, shall be of the anti-turn solderless type and all
shall be suitable for copper conductors of the sizes indicated on the
Drawings.
2.
Interiors shall be designed so that switching and protective devices can
be replaced without disturbing adjacent units and without removing the
main bus connectors and shall be so designed that circuits may be
changed without matching, drilling, or tapping.
D.
Branch circuits shall be arranged using double row construction except where a
narrow column width panelboard is required or noted on the Drawings. Branch
circuits shall be numbered by the manufacturer.
E.
Furnish and install three (3), 3/4 inch and two (2), one inch empty conduits up
through the wall and turned out above the ceiling; and three (3), 3/4 inch and two
(2), one inch empty conduits down into the ceiling space below the floor for all
flush mounted branch circuits panelboards. Where floor slab is on grade,
provide only empty conduits to the ceiling.
F.
All surface mounted branch circuit panelboards shall be mounted on twelve (12)
gauge formed steel channel having a cross section dimension at least 1-1/2
inches x 1-1/2 inches on walls. The channel and fittings shall have a hot dipped
galvanized finish to resist rust formation. Channels shall be installed vertically
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SECTION 16435
and as detailed on the Drawings.
G.
H.
Bus Bars:
1.
Bus bars for the mains shall be of copper sized in accordance with UL 67
Standards for temperature rise to limit temperature rise on any current
carrying part to a maximum of 65 degrees C above an ambient of 40
degrees C maximum. The bus bars shall be standard density rated for
1000 amperes per square inch copper. Bus bar taps for branch circuit
panelboards with single pole branches shall be arranged for sequence
phasing of the branch circuit devices. Busing shall be braced throughout
to conform to industry standard practice governing short circuit stresses
in panelboards. Phase busing shall be full height without reduction.
Cross connectors shall be copper. A non-insulated copper ground bus
shall be provided for each panelboard.
2.
Phase busing shall be manufactured to accept bolt-on circuit breakers
only.
3.
Spaces for the addition of future switching and protective devices in
branch circuit panelboards shall be bussed for the maximum number of
devices possible complete with pre-drilled mounting holes and knockouts
in the front cover.
4.
A non-insulated copper ground bus shall be provided for each branch
circuit panelboard.
5.
Full size (100% rated) insulated neutral busing shall be included for
panelboards shown with a neutral. Neutral busing shall have a suitable
lug for each outgoing feeder or branch circuit requiring a neutral
connection.
6.
Lugs shall be rated for 75 degrees C terminations and shall bolt in place.
Backboxes:
1.
Backboxes shall be made from unpainted galvanized code gauge steel
having no knockouts.
2.
Boxes shall have gutter and wiring space sized as required per NEC but
not less than four (4) inches on all sides. Where feeder cables supplying
the mains of a panelboard are carried through the box to supply other
electrical equipment, the box shall be so sized as to include this wiring
space. This wiring space shall be in addition to the minimum gutter space
specified above and the limiting width may be increased accordingly.
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I.
SECTION 16435
3.
Backboxes shall also have sufficient space to safely attach clamp-on or
split-core current transformers to the feeders for future portable or
permanent check metering.
4.
Backboxes for multiple (two or more) sections shall be of the same
dimensions.
5.
Each backbox shall include at least four (4) interior mounting studs.
6.
The branch circuit panelboard identification number shall be on the
backbox.
7.
Branch circuit panelboard backboxes shall be of one (1) piece
construction.
Trim:
1.
Hinged doors shall be the door-in-door type covering all switching device
handles and all live parts and shall be included in all branch circuit
panelboard trims.
2.
Doors in branch circuit panelboard trims shall conform to the following:
3.
a.
In making device handles accessible, inboard doors shall not
uncover any live parts. Outboard doors shall allow hinged access
to the interior panel wiring without removal of the panel door
assembly.
b.
Doors shall have a semi-flush type cylinder lock and catch. Door
hinges shall be concealed. Two (2) keys shall be furnished for
each panelboard door and all locks shall be keyed as requested
by the Owner to match current standard. The outer door shall be
keyed separately. Directory frame and card, having a transparent
cover, shall be furnished on the inside of each door.
c.
Directory cards shall be neatly typewritten indicating each branch
circuit number and assignment. The assignment designation shall
include the final room number(s) assigned by the Owner. Do not
use the architectural room numbers shown on the Drawings. The
director cards shall also include the source (switchboard,
panelboard, etc. with circuit number) feeding the panel.
The trims shall be fabricated from code gauge sheet steel.
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BRANCH CIRCUIT PANELBOARDS
J.
2.03
SECTION 16435
4.
All of the panelboard's steel surfaces, exterior and interior shall be
properly cleaned and finished with the manufacturer's standard paint over
a rust-inhibiting phosphatized coating. The finish paint shall be of a type
to which field applied paint will adhere.
5.
Trims for flush mounted branch circuit panelboards shall overlap the box
by at least 3/4 inches on all sides. Surface trims shall be mountable by a
screwdriver without the need for special tools.
Conduit skirts shall be provided on surface mounted branch circuit panelboards,
where shown on the drawings. Skirts shall be the same width and depth as the
panelboard backbox. Screw on skirt covers shall be the same code gauge sheet
steel as the panelboard trim and painted with the same finish and color as the
panelboard. Skirts shall be from the top of the panelboard to the underside of
the finished ceiling and/or from the bottom of the panelboard to the finished floor
concealing all conduits.
CIRCUIT BREAKERS
A.
Electrical circuits shall be protected by molded case circuit breakers as indicated
on the Drawings.
B.
The circuit breakers shall be operated by a toggle type handle and shall have a
quick-make, quick-break over-center switching mechanism that shall be
mechanically trip free from the handle so that the contacts cannot be held closed
against short circuits and abnormal currents. Tripping due to overload or short
circuit shall be clearly indicated by the handle automatically assuming a position
midway between the manual "ON" and "OFF" positions. All latch surfaces shall
be ground and polished. All poles of a multi-pole breaker shall be so constructed
that they open, close, and trip simultaneously.
C.
The circuit breakers shall be completely enclosed in a molded case. Noninterchangeable trip breakers shall have their covers sealed; interchangeable trip
breakers shall have the trip unit sealed to prevent tampering. Ampere ratings
shall be clearly visible. Contacts shall be non-welding silver alloy. Arc extinction
shall be accomplished by means of arc chutes consisting of metal grids mounted
in an insulating support. Breakers shall be of the bolt-on type; plug-in, plug-on,
blow-on, and clamp-on circuit breakers shall not be acceptable.
D.
Circuit breakers shall be 80% rated unless indicated on the Drawings to be 100%
rated.
E.
Circuit breakers shall have a minimum symmetrical interrupting capacity as
indicated on the Drawings. The interrupting ratings of the circuit breakers shall
be at least equal to, or greater than, the available short circuit at the line
terminals and not less than those values shown on the Drawings and specified in
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SECTION 16435
this specification section or as determined by the Short-Circuit Coordination
Study whichever is higher. [ENGINEER, EDIT OUT SHORT-CKT STUDY IF
NOT IN PROJECT]
F.
Circuit breakers shall be listed with UL, conform to the applicable requirements
of the latest issue of NEMA Standards Publication No. AB1.
G.
Circuit breakers shall have thermal-magnetic trip units, with inverse time-current
characteristics, unless otherwise noted on the Drawings and/or specified herein.
H.
1.
Automatic operation of all circuit breakers shall be obtained by means of
thermal-magnetic tripping devices located in each pole providing inverse
time delay and instantaneous circuit protection. Instantaneous pick-up
settings for each phase shall be adjustable on all frames 250A and
above.
2.
Circuit breakers shall be ambient compensating in that, as the ambient
temperature increases over 40° C, the circuit breaker automatically
derates itself to better protect its associated conductor.
3.
Circuit breakers 250A and above shall have thermal magnetic
interchangeable trip units,
Circuit breaker frames 400 ampere and above shall have microprocessor-based
RMS sensing trip units on 480 volt systems and on 208 volt systems where
indicated on the Drawings.
1.
Solid State sensing shall measure true RMS current with capability to
st
measure through to the 21 harmonic. Automatic operation of all circuit
breakers shall be obtained by means of solid state tripping elements
providing inverse time delay and instantaneous and short-time circuit
protection. Continuous current rating shall be adjustable from 20% to
100% of trip unit rating. Long-time delay and instantaneous trip ratings
shall also be adjustable. The short time pick-up trip shall have
adjustable pick-up settings at definite times and with I2t delay.
2.
Long time current adjustment shall be possible without the need for a
rating plug.
3.
Main and feeder circuit breakers shall be provided with integral ground
fault protection in 480 volt panels. Ground fault pick-up shall be
adjustable from 20% to 70% of the breakers maximum continuous
current rating, but in no case be greater than 1200A. Ground fault time
delay shall be adjustable with three (3) I2t delay settings.
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BRANCH CIRCUIT PANELBOARDS
2.04
Solid State circuit breakers shall have built-in test ports for testing the
long-time delay, instantaneous, and ground fault functions (if equipped)
of the breaker by means of a test set.
5.
Provide one test set capable of testing all circuit breakers with a built-in
test port, unless previously provided under another section of these
specifications.
Circuit breaker accessories: Provide shunt trips, bell alarms and auxiliary
switches, etc. as may be shown on the drawings. All accessories shall be UL
Listed for field installation.
J.
Circuit breakers shall be manufactured by the same manufacturer as the
panelboard and factory installed.
K.
Where indicated, circuit breakers shall be UL listed for series application.
(ENGINEER TO EDIT OUT THIS PARAGRAPH IF NOT USING SERIES
CONNECTED BREAKERS.)
MULTIPLE SECTION PANELBOARDS
Panelboards with two (2) or more panelboard sections, sub-feed lugs or thrufeed lugs shall be used in all but one (1) section of each panelboard, unless
otherwise shown on the Drawings. Lugs shall have same capacity as incoming
mains. Cable interconnections shall be field installed.
NAMEPLATES
A.
2.06
4.
I.
A.
2.05
SECTION 16435
Branch circuit panelboards shall have nameplates of 1/16 inch thick laminated
plastic with 3/16 inch high white letters on a black background. Nameplates shall
identify the branch circuit panelboard and shall be mounted on the front top of
the enclosure.
SURGE PROTECTIVE DEVICE (SPD)
A.
Provide surge protective devices (SPD) as specified in Section 16418.
PART 3 - EXECUTION
3.01
INSTALLATION
A.
Before installing branch circuit panelboards, this Contractor shall check all of the
Drawings for possible conflict of space and adjust the location of the branch
circuit panelboard to prevent such conflict with other items. Panelboard locations
in electrical rooms and other spaces shall closely follow the layouts shown on the
Drawings, leaving sufficient space on walls for future installations of panelboards
and/or other electrical equipment.
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BRANCH CIRCUIT PANELBOARDS
3.02
3.03
3.04
SECTION 16435
B.
Surface mounted branch circuit panelboards shall be securely mounted to steel
framing channel at locations shown on Drawings. Construction shall be such
that additional conduits can be added for future requirements.
C.
The cabinets and enclosures shall be mounted in accordance with the NEC.
This Contractor shall furnish all materials necessary for mounting the branch
circuit panelboards.
D.
Install units plumb, level and rigid without distortion to the branch circuit
panelboard.
E.
Branch circuit panelboard interiors shall be factory assembled with circuit
breakers, wire connectors, etc. Circuit breakers shall be sequence numbered to
correspond with the panelboard directory.
F.
Connect the SPD to the appropriate circuit breaker.
G.
Contractor shall install required safety labels.
FIELD TESTS
A.
Check tightness of all accessible mechanical and electrical connections to
assure they are torqued to the minimum acceptable manufacturer’s
recommendations.
B.
Check all panelboards for proper grounding, fastening and alignment.
FIELD ADJUSTMENTS
A.
This Contractor shall perform field adjustments of the protective devices as
required to place the equipment in final operating condition. Necessary field
settings of devices and adjustments and minor modifications to equipment shall
be carried out by this Contractor at no additional cost to the Owner.
B.
(ENGINEER, DELETE THIS PARAGRAPH WHEN SECTION 16015 “SHORTCIRCUIT/COORDINATION STUDY” IS NOT USED) The settings shall be in
accordance with the approved protective device coordination study or as directed
by the Engineer.
CLEANING
A.
Remove debris from panelboards and wipe dust and dirt from all components.
B.
Repaint marred and scratched surfaces with touch-up paint to match original
finish.
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BRANCH CIRCUIT PANELBOARDS
3.05
SECTION 16435
EXISTING BRANCH CIRCUIT PANELBOARDS
A.
This Contractor shall clean, adjust, and tighten all feeder and branch circuit
connections (new and existing) and provide new typewritten directories (as
described above) in all existing branch circuit panelboards that are associated
with work on this project. Panelboard’s not associated with work on this project
are not subject to this requirement.
END OF SECTION
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