1 Scope

NOTE This standard governs the panelboard as a listed assembly: the bus and its supports, the main device where one is furnished, the branch circuit devices and their mounting, the cabinet and its front, the provisions built into the cabinet for surge protection and metering, and the field work that puts the panelboard into service. (1.1)

NOTE A panelboard is a single panel or a group of panel units assembled as one panel, installed in a cabinet and accessible only from the front, that carries buses and overcurrent devices for the control of light, heat, or power circuits; dead-front construction leaves no energized part exposed on the operating face once the front is installed. (1.2)

NOTE The panelboard is the last piece of distribution equipment ahead of the branch circuits, so most projects have many of them, and the values that differ from one panelboard to the next, such as the voltage, the bus rating, the main device, the number of circuits, and the breakers installed, live on the panel schedules; the datasheet of this standard carries the policy that applies to every panelboard on the project unless a schedule states otherwise. (1.3)

NOTE The terms "lighting and appliance branch-circuit panelboard" and "power panelboard", together with the limit of 42 overcurrent devices in one cabinet, were removed from NFPA 70 Article 408 in the 2008 edition; they still appear in older documents and in catalogs, but they carry no code consequence and are not a basis for any requirement in this standard. (1.4)

NOTE The following are governed elsewhere and are outside this standard: (1.5)

switchboards, switchgear, and motor control centers, under Low Voltage SwitchboardsLow Voltage SwitchboardsResolves to the current edition.sync/low-voltage-switchboards, Low Voltage SwitchgearLow Voltage SwitchgearResolves to the current edition.sync/low-voltage-switchgear, and Motor Control CentersMotor Control CentersResolves to the current edition.sync/motor-control-centers
enclosed switches and circuit breakers used as individual disconnects, under Enclosed Switches And DisconnectsEnclosed Switches and DisconnectsResolves to the current edition.sync/enclosed-switches-and-disconnects
the feeders and branch circuit conductors that land in the panelboard and their terminations, under Conductors And CablesConductors and CablesResolves to the current edition.sync/conductors-and-cables
the raceways entering the cabinet, under Raceways And ConduitRaceways and ConduitResolves to the current edition.sync/raceways-and-conduit
the grounding electrode system, the equipment grounding conductors, and the bonding of a separately derived system, under Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current edition.sync/grounding-and-bonding
the service point, the service conductors, and the utility metering, under Electrical Service EntranceElectrical Service EntranceResolves to the current edition.sync/electrical-service-entrance
the surge protective device as a product, its ratings, its protection modes, and its lead length, under Surge Protective DevicesSurge Protective DevicesResolves to the current edition.sync/surge-protective-devices
the meters, their accuracy class, their current transformers, and the monitoring system they report to, under Electrical Power MonitoringElectrical Power Monitoring and MeteringResolves to the current edition.sync/electrical-power-monitoring
the transformer feeding a panelboard and the grounding of its secondary, under Low Voltage Dry Type TransformersLow-Voltage Dry-Type TransformersResolves to the current edition.sync/low-voltage-dry-type-transformers
the receptacles, switches, and outlet devices on the branch circuits, under Wiring DevicesWiring DevicesResolves to the current edition.sync/wiring-devices
the remotely operated breakers, relays, and controllers of a lighting-control panelboard, under Lighting ControlsLighting ControlsResolves to the current edition.sync/lighting-controls
the short-circuit, coordination, and arc-flash studies, under Short Circuit StudyShort-Circuit StudyResolves to the current edition.sync/short-circuit-study, Protective Coordination StudyProtective Device Coordination StudyResolves to the current edition.sync/protective-coordination-study, and Arc Flash StudyArc-Flash Hazard AnalysisResolves to the current edition.sync/arc-flash-study
the room the panelboard occupies, under Electrical RoomsElectrical RoomsResolves to the current edition.sync/electrical-rooms

1.6 Panelboards shall comply with NEMA PB 1 and shall be listed and labeled to UL 67 by a Nationally Recognized Testing Laboratory.

1.7 The location of each panelboard shall be as indicated on the electrical plans.

1.8 The voltage, the bus rating, the main device, the number of circuits, and the branch circuit devices of each panelboard shall be as indicated on the panel schedules.

1.9 Where a value stated on a panel schedule for a particular panelboard differs from the datasheet selection under this standard, the panel schedule shall govern for that panelboard.

2 Referenced Standards

2.1 Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.

2.2 Where the contract documents, the serving utility's requirements, the Authority Having Jurisdiction, or two referenced standards impose conflicting requirements, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.

Standard	Title
UL 67	Panelboards
UL 489	Molded-Case Circuit Breakers, Molded-Case Switches, and Circuit-Breaker Enclosures
UL 943	Ground-Fault Circuit-Interrupters
UL 1053	Ground-Fault Sensing and Relaying Equipment
UL 1699	Arc-Fault Circuit-Interrupters
UL 50	Enclosures for Electrical Equipment, Non-Environmental Considerations
UL 50E	Enclosures for Electrical Equipment, Environmental Considerations
NEMA PB 1	Panelboards
NEMA PB 1.1	General Instructions for Proper Installation, Operation and Maintenance of Panelboards Rated 1000 Volts or Less
NEMA AB 1	Molded-Case Circuit Breakers, Molded-Case Switches, and Circuit-Breaker Enclosures
NEMA 250	Enclosures for Electrical Equipment (1000 Volts Maximum)
NFPA 70	National Electrical Code (Articles 110, 210, 215, 220, 230, 240, 250, 312, 408, 700, 701, and 708)
NFPA 70E	Standard for Electrical Safety in the Workplace
ASTM B187	Copper, Bus Bar, Rod, and Shapes and General Purpose Rod, Bar, and Shapes
ASTM B317	Aluminum-Alloy Extruded Bar, Rod, Tube, Pipe, Structural Profiles, and Profiles for Electrical Purposes (Bus Conductor)
ANSI/NETA ATS	Standard for Acceptance Testing Specifications for Electrical Power Equipment and Systems
ASCE 7	Minimum Design Loads and Associated Criteria for Buildings and Other Structures (Chapter 13)
ICC-ES AC156	Acceptance Criteria for Seismic Certification by Shake-Table Testing of Nonstructural Components

3 Submittals

3.1 Action Submittals

3.1.1 The Contractor shall submit the following for review before any panelboard is released for manufacture:

product data for the panelboard, the main device, the branch circuit devices, and every accessory, identifying the UL 67 listing and, where the panelboard is service equipment, the service equipment listing
shop drawings for each panelboard giving the cabinet dimensions, the mounting arrangement, the front trim, the bus material and rating, the device arrangement, and the conduit entry areas
a panel schedule for each panelboard giving every circuit number, the load served, the pole count, the frame size, the trip rating, and the trip unit type of every device, and every spare and space position
the assembly short-circuit current rating of each panelboard and the basis on which it is established, and where the basis is a series rating, the tested combination and the upstream device on which each rating depends
the seismic certification for the panelboard as furnished, where the datasheet requires one
product data for the surge protective device and the metering furnished within the cabinet, where either is furnished
the nameplate schedule listing the text to appear on each panelboard nameplate

Action Submittalscheckbox

☑ Product data with UL 67 listing

☑ Shop drawings

☑ Panel schedules

☑ Short-circuit current rating basis and series-rated combinations

☐ Seismic certification

☐ Surge protective device and metering product data

☑ Nameplate schedule

3.1.2 A panelboard shall not be released for manufacture until the action submittals covering it have been reviewed and returned.

NOTE The short-circuit current rating is the submittal item that most often comes back wrong, because a catalog rating is the rating of the highest-rated device the cabinet accepts, and the rating that applies to the panelboard is the lowest rating among the bus, the main device, and every branch device actually installed, or the series-rated combination that covers them. (3.1.3)

3.2 Informational Submittals

3.2.1 The Contractor shall submit the following with or before the action submittals:

the manufacturer's qualification statement required under Quality Assurance
the qualifications of the firm and the technicians who will perform field acceptance testing
the factory test procedure, where the datasheet selects witnessed factory testing
the manufacturer's published derating factors applied for ambient temperature and altitude, where either exceeds the rating basis of the listing

Informational Submittalscheckbox

☑ Manufacturer's qualification statement

☑ Field testing firm and technician qualifications

☐ Factory test procedure

☐ Ambient and altitude derating factors

3.3 Closeout Submittals

3.3.1 The Contractor shall submit the following before any panelboard is accepted:

the record panel schedule for each panelboard, reflecting every as-installed circuit assignment and every field change
the certified factory test report, where the datasheet selects witnessed factory testing
the field acceptance test report for each panelboard, giving every measured value, the acceptance criterion applied, and the tester's determination
the ground-fault protection performance test record required by NFPA 70 230.95(C), where ground-fault protection of equipment is furnished
the final settings of every adjustable trip unit
operation and maintenance data covering the panelboard, the devices installed in it, and the inspection and re-torque intervals of NEMA PB 1.1
the warranty certificate identifying each panelboard by designation and the warranty commencement date
a signed receipt from the Owner for the spare parts and keys delivered

Closeout Submittalscheckbox

☑ Record panel schedules

☐ Certified factory test report

☑ Field acceptance test reports

☐ Ground-fault protection performance test record

☑ Final trip unit settings

☑ Operation and maintenance data

☑ Warranty certificate

☑ Spare parts and keys receipt

NOTE The record panel schedule is the document the next electrician reads before opening the cover, and a panelboard whose circuit assignments exist only in the directory card in its door loses them with the first card that is replaced. (3.3.2)

4 Quality Assurance

4.1 Manufacturer Qualifications

4.1.1 The panelboard shall be produced by a manufacturer that has held a UL 67 listing for panelboards of the type furnished for not less than the period indicated in the datasheet.

Minimum Manufacturer Listing Historyrange

years

351020

4.1.2 The manufacturer shall maintain a technical service organization able to reach the site, and shall state in the qualification statement the location of the nearest service center and the period for which replacement devices for the panelboard platform will remain available.

4.2 Source Limitations

4.2.1 The cabinet, the interior, the bus, and the branch circuit devices of every panelboard shall be furnished by the panelboard manufacturer under one UL 67 listing.

4.2.2 Every panelboard on the project shall be furnished by one manufacturer, so that spare devices interchange and the Owner maintains one device family.

4.2.3 A branch circuit device from another maker shall be installed in a panelboard only where the panelboard manufacturer has listed the device for the interior under UL 67, and the assembly short-circuit current rating with that device installed shall be stated in the action submittals.

NOTE A breaker that fits the bus stab is not a breaker that is listed for the panelboard; the UL 67 listing covers the interior with the specific devices evaluated in it, and an unlisted device removes the panelboard from the condition under which its short-circuit current rating was established. (4.2.4)

4.3 Field Testing Firm

4.3.1 Field acceptance testing shall be performed by the firm indicated in the datasheet.

Field Acceptance Testing Firmradio

○ Independent testing firm accredited to ANSI/NETA ATS

○ Manufacturer's field service organization

○ Installing contractor's own technicians

4.3.2 The technicians who perform field acceptance testing shall hold a current certification for low-voltage equipment testing from NETA or from the manufacturer of the equipment tested.

NOTE An independent firm has no stake in whether the panelboard passes and reports against a published acceptance standard; the manufacturer's organization knows the product best; the installing contractor's own technicians cost least and are available on the installer's schedule. Which of these the Owner wants depends on how the results will be used and on whether a report from the party who installed the equipment would satisfy the Owner's insurer and the Authority Having Jurisdiction. (4.3.3)

5 Environmental and Service Conditions

5.1 Ambient Temperature

5.1.1 The panelboard shall carry its nameplate ratings continuously at the design ambient temperature of the space it is installed in.

5.1.2 The design ambient temperature for a panelboard installed indoors shall be as indicated in the datasheet.

Indoor Design Ambient Temperaturerange

°C

2530405055

NOTE Molded-case circuit breakers are calibrated at a 40 °C ambient under UL 489, so a 40 °C design ambient is the condition at which the device ratings apply without correction; a higher value covers a rooftop mechanical room or an unventilated closet whose ambient cannot be held at 40 °C at design load, at the cost of a larger bus or a larger device for the same load. (5.1.3)

5.1.4 A panelboard installed outdoors or in a space that follows the outdoor temperature shall be rated for Site Ambient Temperature MaximumSite Ambient Temperature MaximumParameterEach project supplies its own value.site-ambient-temperature-maximum where that temperature exceeds 40 °C, and the manufacturer shall state the derating applied in the action submittals.

5.2 Altitude

5.2.1 The panelboard and its devices shall be derated for AltitudeAltitudeParameterEach project supplies its own value.altitude in accordance with the manufacturer's published correction factors where the altitude exceeds the 2000 m rating basis of the listing.

NOTE Air thins with altitude, which reduces both the convective cooling that sets the continuous current rating of a device and the dielectric strength of the clearances inside the cabinet, so a panelboard rated at sea level carries less current and less insulation margin at elevation than its nameplate states. (5.2.2)

5.2.3 Ambient temperature derating and altitude derating shall be applied cumulatively where both conditions apply.

5.3 Condensation Control

5.3.1 The space heater provision for the cabinet shall be as indicated in the datasheet.

Cabinet Space Heaterradio

○ No space heater

○ Thermostatically controlled space heater

NOTE A panelboard that stands in an unconditioned space cycles through the dew point with every cold night, and the condensation that forms on the bus, the device terminals, and the insulating supports is the mechanism behind most tracking failures on outdoor and unheated panelboards. (5.3.2)

5.3.3 Where the panelboard is installed outdoors or in a space that is not conditioned, a space heater shall be furnished unless the datasheet selects no space heater.

5.3.4 Where a space heater is furnished, it shall be sized to hold the interior of the cabinet above the dew point at Site Ambient Temperature MinimumSite Ambient Temperature MinimumParameterEach project supplies its own value.site-ambient-temperature-minimum, and shall be supplied from a circuit that stays energized while the panelboard main device is open.

5.4 Seismic Qualification

5.4.1 The seismic certification required for the panelboard shall be as indicated in the datasheet.

Seismic Certification Requirementselect

Not required

Anchorage design only per ASCE 7 Chapter 13

Special seismic certification by shake-table test per ICC-ES AC156 or by analysis accepted by the Authority Having Jurisdiction

Derived — Seismic Design CategorySeismic Design CategoryParameterEach project supplies its own value.seismic-design-category and the component importance factor assigned to the panelboard under ASCE 7 Chapter 13 (by default)

NOTE Anchorage keeps the panelboard on its wall or floor; special certification demonstrates that the devices in it still function after the design earthquake, which ASCE 7 requires of a component whose importance factor is above 1.0, such as a panelboard serving egress lighting, a fire pump, smoke control, or another load a Risk Category IV facility depends on. (5.4.2)

5.4.3 Where seismic certification is required, it shall be performed in accordance with the seismic provisions of Adopted Building CodeAdopted Building CodeParameterEach project supplies its own value.adopted-building-code and ASCE 7 Chapter 13, and the certificate shall cover the panelboard as furnished, including the cabinet, the interior, and the devices installed.

5.4.4 A field change to the devices installed or to the mounting that departs from the certified configuration shall be re-evaluated by the manufacturer against the certification before the panelboard is energized.

6 Electrical Ratings

6.1 Service Configuration

6.1.1 Whether the panelboard is service equipment shall be as indicated in the datasheet.

Service Configurationradio

○ Service equipment

○ Downstream distribution equipment

Per drawings — the one-line diagram (deferred by default)

6.1.2 Where the panelboard is service equipment, it shall be listed as suitable for use as service equipment and shall comply with NFPA 70 Article 230, including the service disconnecting means, the available fault current marking, the main bonding jumper, and the grounding electrode conductor termination furnished under Electrical Service EntranceElectrical Service EntranceResolves to the current edition.sync/electrical-service-entrance and Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current edition.sync/grounding-and-bonding.

6.1.3 Where the panelboard is service equipment, the number of service disconnects in the cabinet shall not exceed the number NFPA 70 230.71 permits for the service, and each shall be marked as a service disconnect.

6.2 System Voltage and Frequency

6.2.1 The system voltage and configuration shall be as indicated in the datasheet.

System Voltageselect

120/240 V 1Φ 3-wire

208Y/120 V 1Φ 3-wire, two phases and neutral

208Y/120 V 3Φ 4-wire

240 V 3Φ 3-wire delta

240/120 V 3Φ 4-wire high-leg delta

480Y/277 V 3Φ 4-wire

480 V 3Φ 3-wire delta

600Y/347 V 3Φ 4-wire

600 V 3Φ 3-wire delta

Per drawings — the panel schedules (deferred by default)

NOTE The number of phases and the number of wires follow from the system voltage selected, and the number of poles on the main device and the presence of a neutral bus follow from them in turn. (6.2.2)

6.2.3 The panelboard voltage rating shall equal or exceed the system voltage, and where the panelboard is fed from a transformer secondary the Contractor shall confirm the rating against the secondary configuration selected under Low Voltage Dry Type TransformersLow-Voltage Dry-Type TransformersResolves to the current edition.sync/low-voltage-dry-type-transformers before the panelboard is released for manufacture.

6.2.4 Where the system is a high-leg delta, the high leg shall be connected to the B phase of the bus, shall be identified in accordance with NFPA 70 110.15 and 408.3(F), and single-pole devices shall not be installed on the high-leg phase.

6.2.5 Where the system is a 3-wire delta or another system with no grounded conductor at the panelboard, the panelboard shall be furnished without a neutral bus and the devices shall be rated for the line-to-line voltage.

6.2.6 The system frequency shall be as indicated in the datasheet.

System Frequencyradio

● 60 Hz

○ 50 Hz

6.3 Main Bus Continuous Current

6.3.1 The main bus continuous current rating shall be as indicated in the datasheet.

Main Bus Continuous Currentrange

A

60100125150200225250400600800100012001600

Per drawings — the panel schedules (deferred by default)

6.3.2 The main bus rating shall be not less than the rating of the main device where one is furnished, and not less than the rating of the feeder overcurrent device where the panelboard has main lugs only.

NOTE The bus rating is fixed per panelboard by the calculated load of NFPA 70 Article 220 and the spare capacity the project wants to leave, and it is stated on the panel schedule with the main device that protects it; the datasheet field records the rating only where one rating applies across the project. (6.3.3)

6.4 Short-Circuit Current Rating

6.4.1 The available fault current at the line terminals of each panelboard shall be as indicated on the panel schedules.

6.4.2 The assembly short-circuit current rating marked on the nameplate of each panelboard shall equal or exceed the available fault current at its line terminals as established under Short Circuit StudyShort-Circuit StudyResolves to the current edition.sync/short-circuit-study, and shall be as indicated in the datasheet.

Assembly Short-Circuit Current Ratingrange

kA

1014182225303542506585100150200

Per drawings — the panel schedules (deferred by default)

NOTE The marked assembly rating is the lowest of the bus bracing, the interrupting rating of the main device, and the interrupting rating of every branch device, or the rating of the series-rated combination that covers them, so a single device of a lower rating installed in the field lowers the rating of the whole panelboard. (6.4.3)

6.4.4 The bus short-circuit bracing shall be as indicated in the datasheet.

Bus Short-Circuit Bracingrange

kA

1014182225303542506585100150200

Derived — the assembly short-circuit current rating; the bus is braced to not less than the rating marked on the panelboard (by default)

NOTE The available fault current at each panelboard is a property of the source, the transformer, and the feeder ahead of it, and it is recalculated when any of those change; the study establishes it, the panel schedule carries it, and the panelboard is rated against it. (6.4.5)

6.5 Interrupting Rating Basis

6.5.1 The basis on which the interrupting ratings of the devices in the panelboard are established shall be as indicated in the datasheet.

Interrupting Rating Basisradio

○ Fully rated

○ Series rated

NOTE In a fully rated panelboard every device carries an interrupting rating that stands on its own at the available fault current; in a series-rated panelboard the branch devices carry a lower individual rating and reach the marked rating only in combination with the specific upstream device they were tested with, which NFPA 70 240.86 permits where the combination is listed. Series rating lowers the cost of the branch devices where the available fault current is high, and it makes the rating depend on an upstream device that must stay in place for the life of the installation; full rating costs more per device and depends on nothing upstream. (6.5.2)

6.5.3 The interrupting rating of the branch circuit devices shall be as indicated in the datasheet.

Branch Circuit Device Interrupting Ratingrange

kA

1014182225303542506585100150200

Derived — the assembly short-circuit current rating and the interrupting rating basis; under a fully rated basis every device equals or exceeds the assembly rating, and under a series rated basis the listed combination fixes the branch device rating (by default)

6.5.4 Where series rating is the basis, the combination shall be one the manufacturer has tested and listed under UL 67 and UL 489 in accordance with NFPA 70 240.86(B), and the upstream device on which each rating depends shall be identified in the action submittals.

6.5.5 Where series rating is the basis, the panelboard shall be field-marked in accordance with NFPA 70 110.22(C) to identify the series combination and the replacement devices it depends on.

6.5.6 Where series rating is the basis, the Contractor shall confirm that the sum of the motor full-load currents connected between the upstream device and the panelboard does not exceed the limit NFPA 70 240.86(C) sets for the branch device rating, and shall report a combination that exceeds it to the Engineer of Record before the panelboard is released for manufacture.

6.5.7 Where the panelboard serves a system that NFPA 70 Article 700, 701, or 708 requires to be selectively coordinated, a series-rated combination shall not be relied on within the coordinated path, because the upstream device of a series combination opens with the branch device on a high-magnitude fault.

6.5.8 Where a device in a series-rated panelboard is replaced, the replacement shall be of the same manufacturer, type, and rating named in the listed combination.

7 Main Device

7.1 Main Device Type

7.1.1 The main device of the panelboard shall be as indicated in the datasheet.

Main Device Typeselect

Main lugs only

Main circuit breaker

Main fusible switch

Per drawings — the panel schedules (deferred by default)

7.1.2 The main device frame size and trip rating, or the switch and fuse rating, shall be as indicated on the panel schedules.

NOTE A main circuit breaker gives the panelboard a disconnecting means and an overcurrent device at the cabinet, which is what a service disconnect, a tenant disconnect, and a panelboard whose feeder device is out of sight or out of reach each need; main lugs only leaves both functions to the feeder device upstream and saves the cost and the cabinet height of the main; a main fusible switch is the construction used where the fault current calls for a current-limiting fuse or where the Owner's device family is fused. (7.1.3)

7.1.4 Where the panelboard has main lugs only, it shall be protected by an overcurrent device on the supply side whose rating does not exceed the bus rating, in accordance with NFPA 70 408.36, and that device shall be accessible as the disconnecting means for the panelboard.

7.1.5 Where the panelboard is service equipment, the main device shall be the service disconnecting means and shall be rated in accordance with NFPA 70 Article 230.

7.1.6 The main device operating handle shall accept a padlock in the open position.

7.2 Main Circuit Breaker Trip Unit

7.2.1 Where a main circuit breaker is furnished, its trip unit shall be as indicated in the datasheet.

Main Circuit Breaker Trip Unitselect

Thermal-magnetic

Electronic with long-time and instantaneous functions

Electronic with long-time, short-time, and instantaneous functions

Electronic with long-time, short-time, instantaneous, and ground-fault functions

Per drawings — the panel schedules (deferred by default)

NOTE A thermal-magnetic trip unit has a fixed time-current characteristic, an instantaneous setting that is adjustable on the larger frames only, and no communications, and it is the construction the smaller frames are built with; an electronic trip unit has adjustable long-time, short-time, and instantaneous settings, which is what selective coordination with the upstream device is set with, and it is the construction the larger frames are built with; the ground-fault function on an electronic trip unit is one of the two ways ground-fault protection of equipment is furnished where code requires it. (7.2.2)

7.2.3 Where a main circuit breaker with an electronic trip unit is furnished, its settings shall be as established under Protective Coordination StudyProtective Device Coordination StudyResolves to the current edition.sync/protective-coordination-study, and the settings as commissioned shall be recorded in the closeout submittals.

7.3 Ground-Fault Protection of Equipment

7.3.1 Ground-fault protection of equipment on the main device shall be as indicated in the datasheet.

Ground-Fault Protection of Equipment on the Main Deviceselect

Not provided

Integral to the main circuit breaker electronic trip unit

Separate ground-fault relay and sensor listed to UL 1053

Derived — NFPA 70 230.95 and 215.10 applied to the system voltage, the main device rating, and whether the panelboard is service equipment (by default)

NOTE Whether the main device must carry ground-fault protection of equipment is fixed by code from the system grounding, the voltage to ground, and the device rating, so the field records the consequence of those inputs rather than a preference; a project may add ground-fault protection where code does not require it, and where it is required the means of providing it is the project selection. (7.3.2)

7.3.3 Where ground-fault protection of equipment is furnished, it shall open all ungrounded conductors of the panelboard at a ground-fault pickup not exceeding 1200 A and within one second for a ground-fault current of 3000 A or more, in accordance with NFPA 70 230.95(A).

7.3.4 Where ground-fault protection of equipment is furnished on a panelboard that is not service equipment, its pickup and delay shall be set to coordinate with the ground-fault protection upstream as established under Protective Coordination StudyProtective Device Coordination StudyResolves to the current edition.sync/protective-coordination-study.

7.3.5 Where ground-fault protection of equipment is furnished, the Contractor shall have it performance-tested by primary current injection after installation in accordance with NFPA 70 230.95(C), and the written record shall be delivered with the closeout submittals.

NOTE Ground-fault protection of equipment protects the bus and the conductors from the arcing damage of a low-magnitude ground fault that the main device would not clear promptly; it does not protect a person, and it is not a substitute for the ground-fault circuit-interrupter protection NFPA 70 210.8 requires on branch circuits. (7.3.6)

7.4 Arc Energy Reduction

7.4.1 Where a circuit breaker in the panelboard is rated or can be adjusted to 1200 A or more, arc energy reduction shall be provided in accordance with NFPA 70 240.87 by the method indicated in the datasheet.

Arc Energy Reduction Methodselect

Not applicable, no device rated 1200 A or more

Energy-reducing maintenance switching with local status indicator

Zone-selective interlocking

Differential relaying

Energy-reducing active arc-flash mitigation system

Instantaneous trip setting below the available arcing current

Derived — NFPA 70 240.87 applied to the rating of the main device and of each feeder device shown on the panel schedules (by default)

NOTE Whether arc energy reduction is required is fixed by the device rating, so the field carries the consequence of the panel schedules; only the method is a project selection where the threshold is met. (7.4.2)

NOTE An energy-reducing maintenance switch lowers the instantaneous pickup for the duration of the work and depends on a worker turning it on; zone-selective interlocking and differential relaying act without a worker's intervention but need the downstream devices or the current transformers to be part of the scheme; an active mitigation system detects the arc by light and current and clears it faster than any trip unit, at the highest cost; an instantaneous setting below the arcing current works only where the arcing current at the panelboard is well above the load current. (7.4.3)

7.4.4 Where energy-reducing maintenance switching is selected, the switch shall be lockable in the maintenance position and its status shall be indicated at the switch.

7.4.5 Where arc energy reduction is furnished, the Contractor shall perform the performance test NFPA 70 240.87(C) requires and shall deliver the documentation NFPA 70 240.87(A) requires with the closeout submittals.

8 Bus

8.1 Phase Bus Material

8.1.1 The phase bus material shall be as indicated in the datasheet.

Phase Bus Materialradio

○ Copper

○ Aluminum

NOTE Copper bus carries more current per unit cross-section, has the lower contact resistance at a bolted joint, and costs more; aluminum bus is lighter and less expensive for the same rating, and its joints depend on the plating and on the joint hardware to hold their resistance through thermal cycling, which is why aluminum is chosen where the cost difference on a large bus matters and copper is chosen where the joint count is high or the environment attacks aluminum. (8.1.2)

8.1.3 Where copper bus is selected, it shall be copper bus bar conforming to ASTM B187 with a conductivity of not less than 98% IACS.

8.1.4 Where aluminum bus is selected, it shall be an aluminum alloy bus conductor conforming to ASTM B317 with a conductivity of not less than 55% IACS, and shall be plated over its full length.

8.1.5 A joint between an aluminum bus and a copper conductor or terminal shall be made with a connector listed for the combination.

8.2 Bus Plating

8.2.1 The bus plating shall be as indicated in the datasheet.

Bus Platingradio

○ Unplated

○ Tin-plated

○ Silver-plated

Manufacturer's standard (by default)

8.2.2 The manufacturer shall state the plating in the product data.

NOTE Unplated copper bus holds its contact resistance in a clean, dry interior and is the construction most panelboards are built with; tin plating resists the sulfur compounds that blacken silver and raise its contact resistance, and is the plating that holds its resistance where the atmosphere carries hydrogen sulfide, as in a wastewater facility; silver plating has the lowest contact resistance in a clean atmosphere. Aluminum bus is plated in every construction because its oxide forms within minutes of exposure and is an insulator. (8.2.3)

8.2.4 Where plating is furnished, it shall be continuous over every bolted joint contact surface and over the full length of the device stab contact area.

8.3 Neutral Bus

8.3.1 The neutral bus shall be as indicated in the datasheet.

Neutral Busselect

No neutral bus

Neutral bus rated 100% of the phase bus

Neutral bus rated 200% of the phase bus

Derived — the system voltage configuration and the share of nonlinear load served from the panelboard (by default)

NOTE A three-wire system has no neutral to carry, a four-wire system carries one rated with the phase bus, and a four-wire system whose load is predominantly single-phase nonlinear equipment, such as switch-mode power supplies, LED drivers, and single-phase drives, carries the triplen harmonic currents that add in the neutral rather than cancel, which is the condition under which the neutral is rated above the phase bus. (8.3.2)

8.3.3 Where a neutral bus is furnished, it shall be insulated from the cabinet, and where the panelboard is service equipment the main bonding jumper shall be furnished by the manufacturer and installed in accordance with Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current edition.sync/grounding-and-bonding.

8.3.4 Where a neutral bus is furnished, it shall have not fewer than one terminal for every branch circuit position in the panelboard, and each neutral conductor shall be terminated in its own terminal in accordance with NFPA 70 408.41.

8.3.5 Where a neutral bus rated 200% of the phase bus is furnished, its terminals and the feeder neutral lug shall be sized for the neutral conductor that the rating implies.

8.4 Equipment Ground Bus

8.4.1 Each panelboard shall be furnished with an equipment grounding terminal bar bonded to the cabinet, with not fewer than one terminal for every branch circuit position, in accordance with NFPA 70 408.40.

8.4.2 Whether an isolated equipment ground bus is furnished shall be as indicated in the datasheet.

Isolated Equipment Ground Busradio

● Not furnished

○ Furnished

NOTE An isolated equipment ground bus is mounted on insulating standoffs so that the isolated grounding conductors of the circuits that use it return to the grounding point of the derived system without picking up the noise currents on the cabinet; it serves the isolated-ground receptacle circuits of NFPA 70 250.146(D), and a bus furnished where no such circuit exists adds cost and invites a termination on the wrong bar. (8.4.3)

8.4.4 Where an isolated equipment ground bus is furnished, it shall be insulated from the cabinet, shall be identified as the isolated ground bus, and shall be connected as Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current edition.sync/grounding-and-bonding requires for the circuits it serves.

8.4.5 Grounding and bonding of the panelboard shall comply with Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current edition.sync/grounding-and-bonding.

8.5 Bus Arrangement and Bracing

8.5.1 The phase bus shall be arranged so that the phase sequence is A, B, C from front to back, top to bottom, or left to right as viewed from the front, in accordance with NFPA 70 408.3(E).

8.5.2 The bus shall be of distributed-phase construction, so that a two-pole or three-pole device installed at any listed position connects to adjacent phases in sequence.

8.5.3 The bus shall be supported on insulating supports that withstand the bus short-circuit bracing indicated in the datasheet without damage, and the bus and its supports shall be rated for the system voltage.

8.5.4 Bus joints shall be bolted with hardware that maintains contact pressure through thermal cycling, and the joint hardware and torque shall be those established under the listing.

8.5.5 Every unused device position on the bus shall be covered by a filler plate in the front when the panelboard is delivered, so that no bus stab is exposed with the door open.

8.6 Feed-Through and Sub-Feed Provisions

8.6.1 Feed-through lugs, sub-feed lugs, and sub-feed breakers shall be furnished on the panelboards indicated on the panel schedules.

8.6.2 Where feed-through lugs are furnished, they shall be rated for the full bus current, shall be mounted on the load end of the bus, and shall accept the conductor size and count indicated on the panel schedule.

8.6.3 Where a panelboard is furnished in two sections because its circuit count exceeds one cabinet, both sections shall carry the full bus rating, the second section shall be fed from the first through sub-feed lugs or a sub-feed breaker furnished by the manufacturer, and the two sections shall carry one panelboard designation with a section suffix.

NOTE A feed-through lug passes the full bus current on to a second panelboard without a device at the first, so the feeder device upstream protects both; a sub-feed breaker adds a device at the first panelboard so that the second is protected and can be isolated on its own. (8.6.4)

9 Cabinet and Front

9.1 Enclosure Type

9.1.1 The enclosure type shall be as indicated in the datasheet.

Enclosure Type per NEMA 250select

Type 1

Type 2

Type 3R

Type 4

Type 4X

Type 12

NOTE A dry, conditioned interior space is the installed location on most projects, which is why Type 1 is the default; every other location named in the clauses of this article calls for the type those clauses require. (9.1.2)

9.1.3 The cabinet shall comply with UL 50 and, for a type other than Type 1, with UL 50E and NEMA 250 for the type selected, and the type shall be marked on the cabinet.

9.1.4 A panelboard installed outdoors shall have an enclosure of Type 3R, Type 4, or Type 4X.

9.1.5 A panelboard installed where it is subject to hose-directed water or wash-down shall have an enclosure of Type 4 or Type 4X.

9.1.6 A panelboard installed where the atmosphere carries salt, chemical vapor, or another corrosive agent, including a coastal site, a wastewater facility, and a food-processing area, shall have a Type 4X enclosure.

9.1.7 A panelboard installed indoors where airborne dust, lint, or fibers accumulate shall have an enclosure of Type 12, Type 4, or Type 4X.

9.1.8 A panelboard installed indoors where dripping or light splashing of a non-corrosive liquid occurs shall have an enclosure of Type 2, Type 12, Type 4, or Type 4X.

9.1.9 Where a rating higher than the datasheet selection is required by the clauses of this article for the installed location, the higher rating shall be furnished and the conflict reported to the Engineer of Record before the panelboard is released for manufacture.

NOTE A field opening cut in a Type 3R, Type 4, Type 4X, or Type 12 cabinet other than at a location and by a method the listing permits removes the environmental rating, and the rework is charged to the party that made the cut. (9.1.10)

9.2 Enclosure Material and Finish

9.2.1 The cabinet material shall be as indicated in the datasheet.

Cabinet Materialselect

Galvanized steel with painted front

Painted steel

Type 304 stainless steel

Type 316 stainless steel

Non-metallic

NOTE A galvanized steel box with a painted front is the construction the indoor panelboard is built with, and it serves every enclosure type in a non-corrosive exposure; stainless steel and non-metallic cabinets are what a Type 4X rating is built in, with Type 316 holding up where chlorides are present and a non-metallic cabinet holding up where the corrodent attacks stainless steel. (9.2.2)

9.2.3 Where the datasheet selects a Type 4X enclosure, the cabinet material shall be one for which the Type 4X rating is listed.

9.2.4 The cabinet and the front shall be formed from steel of not less than the thickness UL 50 requires for the cabinet dimensions, and the front shall be reinforced so that the door does not deflect when opened.

9.2.5 The finish color of the front shall be as indicated in the datasheet.

Front Finish Colorselect

ANSI 61 light gray

ANSI 49 medium gray

White

Custom color matched to a sample furnished by the Owner

9.2.6 A painted front shall carry a baked powder coat or enamel finish over a phosphate pretreatment, and the manufacturer shall state the finish system in the product data.

9.3 Mounting Arrangement

9.3.1 The mounting arrangement shall be as indicated in the datasheet.

Mounting Arrangementselect

Surface mounted

Flush mounted

Semi-flush mounted

Floor standing

Per drawings — the panel schedules (deferred by default)

NOTE A flush-mounted cabinet is recessed so that the front sits at the finished wall, and once the wall is closed it accepts a new circuit only through a raceway that was left at rough-in; a surface-mounted cabinet stands proud of the wall and accepts a raceway at any time; a floor-standing panelboard is the construction the larger frames are built in and is set on a pad like a switchboard. (9.3.2)

9.3.3 A panelboard shall be furnished floor standing where its frame exceeds the manufacturer's published wall-mount limit, whatever the datasheet selects.

9.3.4 A column-width panelboard shall be furnished where indicated on the electrical plans, with its pull box and its device arrangement as the manufacturer lists for that construction.

9.3.5 Where a flush-mounted panelboard is furnished, the Contractor shall install the number of empty raceways indicated in the datasheet from the cabinet to an accessible location above the ceiling, capped and identified at both ends.

Flush-Mount Spare Racewaysrange

count

08

NOTE The spare raceways are the only economical path to a new circuit once a flush-mounted cabinet is walled in, and the count is a judgment about how much future flexibility the Owner is buying at the time the wall is open. (9.3.6)

9.4 Front Trim and Door

9.4.1 The front construction shall be as indicated in the datasheet.

Front Constructionradio

● Trim with hinged door

○ Door-in-door trim with hinged trim and hinged door

○ Trim without door

NOTE A trim with a hinged door gives access to the device handles with the trim screwed in place and the bus covered; a door-in-door trim hinges the whole trim as well, so that the interior can be reached for wiring without removing the trim and without exposing the bus to a dropped panel; a trim without a door leaves the device handles exposed and is the construction used in a locked electrical room where the handles are meant to be reached without a key. (9.4.2)

9.4.3 The front shall be of dead-front construction, concealing every energized part and every device line terminal with the door open.

9.4.4 The door shall be hinged on a continuous hinge, shall open not less than 90 degrees, and shall be fitted with a flush cylinder lock and latch.

9.4.5 The keying of the door locks shall be as indicated in the datasheet.

Door Lock Keyingradio

● Keyed alike across the project

○ Keyed to the Owner's existing panelboard key

9.4.6 Two keys shall be furnished for each panelboard, and the Contractor shall deliver every key to the Owner against a signed receipt.

9.4.7 A directory holder with a transparent cover shall be mounted on the inside of the door.

9.4.8 Where the front is a trim without door, the interior shall be covered by a dead-front that exposes the device handles only.

9.5 Wiring Gutters and Conduit Entry

9.5.1 The wiring gutters on every side of the interior shall be sized for the conductors that enter the cabinet in accordance with NFPA 70 312.6, and the box width shall be not less than 20 in.

9.5.2 Where the panel schedules indicate a conductor size or count for which the standard gutters do not satisfy NFPA 70 312.6, the manufacturer shall furnish a wider or deeper cabinet, and the gutter dimensions shall be shown on the shop drawings.

9.5.3 Conduit shall enter the cabinet through the top, the bottom, or the side end walls as indicated on the electrical plans, and a raceway shall not enter through the back of a flush-mounted cabinet.

9.5.4 A cabinet in a Type 3R, Type 4, or Type 4X enclosure shall be entered only with hubs or fittings listed for the enclosure type, and every unused opening shall be closed with a fitting listed for the type.

9.5.5 A cabinet shall be furnished with blank end walls for field-punched openings, and the manufacturer shall not furnish concentric or eccentric knockouts on a cabinet of a type other than Type 1.

10 Branch Circuit Devices

10.1 Branch Circuit Breaker Mounting

10.1.1 Branch circuit breakers shall be listed to UL 489, and their mounting shall be as indicated in the datasheet.

Branch Circuit Breaker Mountingradio

● Bolt-on

○ Plug-on

○ Plug-on with plug-on neutral bus

NOTE A bolt-on breaker is secured to the bus with a bolt at each pole, which holds its contact pressure through vibration and through repeated operation; a plug-on breaker engages the bus stab with a spring clip and is installed and removed without a tool, at the cost of a connection that depends on the clip's tension; a plug-on neutral interior adds a neutral rail that a ground-fault or arc-fault breaker engages directly, which removes the neutral pigtail those breakers otherwise need. (10.1.2)

10.1.3 Branch circuit breakers shall be the panelboard manufacturer's breakers listed for the interior, and a breaker of another manufacturer shall be installed only as permitted under Source Limitations.

10.1.4 A breaker shall be installed only in a position the listing designates for its frame and pole count, and a tandem breaker shall be installed only in a position listed to accept it and only where the resulting device count does not exceed the number for which the panelboard is listed, in accordance with NFPA 70 408.54.

NOTE A tandem breaker doubles the circuits in one position but does not raise the listed device count of the panelboard, and installing tandems in positions not listed for them to fit more circuits into a full panelboard is the field expedient that fails inspection. (10.1.5)

10.2 Branch Circuit Breaker Ratings

10.2.1 The frame size, the pole count, the trip rating, and the trip unit type of every branch circuit breaker shall be as indicated on the panel schedules.

10.2.2 Where the panel schedule does not indicate a trip unit type for a branch circuit breaker, the breaker shall be thermal-magnetic.

10.2.3 Every branch circuit breaker shall be rated for the system voltage, and a single-pole breaker on a system of more than 120 V to ground shall be rated for the line-to-ground voltage of that system.

10.2.4 A breaker used as the switch for a 120 V or 277 V fluorescent lighting circuit shall be marked SWD or HID, and a breaker used as the switch for a high-intensity discharge lighting circuit shall be marked HID, in accordance with NFPA 70 240.83(D).

10.2.5 Multi-pole breakers shall be common-trip, so that every pole opens when any pole trips, and identified handle ties on single-pole breakers shall be used in place of a multi-pole breaker only where NFPA 70 240.15(B) permits them.

10.2.6 Every branch circuit breaker shall have a trip-free mechanism and a handle that indicates the on, off, and tripped positions.

10.3 Spare Positions

Minimum Spare Branch Circuit Positionsrange

%

1015202530

10.3.2 The form in which spare positions are furnished shall be as indicated in the datasheet.

Spare Position Provisionradio

○ Bussed spaces with filler plates

○ Spare circuit breakers installed

NOTE A bussed space is a position with its stab or bolt connection in place and a filler plate in the front, ready to receive a breaker of any listed rating; a spare breaker installed is a device bought now, marked spare, and left open, which lets a circuit be added without a purchase but commits the trip rating in advance. (10.3.3)

10.3.4 Where spare circuit breakers are installed, the trip rating and pole count of the spares shall be as indicated on the panel schedules, and each spare shall be left in the open position and identified as a spare.

10.3.5 Every space position shall be bussed and provided with the mounting hardware needed to receive a breaker without modifying the interior.

10.4 Personnel Ground-Fault and Arc-Fault Protection

10.4.1 The location at which ground-fault circuit-interrupter protection for personnel is provided on the branch circuits NFPA 70 210.8 requires it shall be as indicated in the datasheet.

Personnel Ground-Fault Protection Locationradio

○ Ground-fault circuit-interrupter breakers at the panelboard

○ Ground-fault circuit-interrupter receptacles and devices at the outlet

NOTE A ground-fault circuit-interrupter breaker protects the whole branch circuit, including its conductors, and is reset at the panelboard; a ground-fault circuit-interrupter receptacle protects the receptacle and the outlets downstream of it, costs less per circuit, and is reset where the person who tripped it is standing. Which is wanted depends on whether the conductors need protection, on who is expected to reset a trip, and on whether the panelboard is accessible to that person. (10.4.2)

10.4.3 Where the panel schedules designate a circuit for a protection location other than the datasheet selection, the panel schedule shall govern for that circuit.

10.4.4 Where ground-fault circuit-interrupter breakers are furnished, they shall be listed to UL 943 as Class A devices, and the receptacles and devices on those circuits shall comply with Wiring DevicesWiring DevicesResolves to the current edition.sync/wiring-devices.

10.4.5 The means of arc-fault circuit-interrupter protection on the branch circuits NFPA 70 210.12 requires it shall be as indicated in the datasheet.

Arc-Fault Protection Meansradio

○ Combination-type arc-fault circuit-interrupter breakers at the panelboard

○ Outlet branch-circuit arc-fault circuit-interrupter devices at the first outlet

○ Not applicable, no branch circuit requiring arc-fault protection

10.4.6 The branch circuits on which NFPA 70 210.12 requires arc-fault protection shall be as indicated on the panel schedules.

10.4.7 Where arc-fault circuit-interrupter breakers are furnished, they shall be combination-type devices listed to UL 1699, and where a circuit requires both arc-fault and ground-fault protection a dual-function breaker listed to both UL 1699 and UL 943 may be furnished in place of two devices.

10.4.8 Where outlet branch-circuit arc-fault protection is selected, the branch circuit from the panelboard to the first outlet shall be installed by a wiring method NFPA 70 210.12 permits for that arrangement, and the device at the first outlet shall comply with Wiring DevicesWiring DevicesResolves to the current edition.sync/wiring-devices.

10.5 Breaker Accessories

10.5.1 Handle lock-on devices, handle padlock provisions, shunt trips, auxiliary contacts, and bell alarms shall be furnished on the branch circuit breakers designated on the panel schedules.

NOTE A handle lock-on device holds a breaker closed against an unintended manual opening and is the provision NFPA 70 requires on a fire alarm circuit and on other circuits that must not be switched off in error; a shunt trip lets a breaker be opened from a remote contact, as at a kitchen hood suppression system or an emergency power off station; an auxiliary contact reports the breaker position to a control system. (10.5.2)

10.5.3 Where a shunt trip is furnished, the control voltage and the source of the trip signal shall be as indicated on the panel schedules, and the trip circuit shall be tested through its initiating device before the panelboard is accepted.

10.5.4 Where the panel schedules designate a panelboard as a lighting-control panelboard, its remotely operated breakers, their controller, and their power supply shall comply with Lighting ControlsLighting ControlsResolves to the current edition.sync/lighting-controls and shall be installed by the manufacturer in the interior under the UL 67 listing.

11 Surge Protection and Metering Provisions

11.1 Surge Protective Device Provisions

11.1.1 Surge protective devices shall be furnished at the panelboards indicated on the one-line diagram, and the device, its ratings, its protection modes, and its lead length shall comply with Surge Protective DevicesSurge Protective DevicesResolves to the current edition.sync/surge-protective-devices.

11.1.2 Where a surge protective device is furnished at a panelboard, its mounting arrangement shall be as indicated in the datasheet.

Surge Protective Device Mounting Arrangementradio

○ Integral, factory-installed within the cabinet

○ External, mounted adjacent to the cabinet and connected through a dedicated breaker

NOTE An integral device is connected to the bus by the manufacturer with the shortest lead the cabinet allows, is covered by the panelboard listing, and takes the cabinet with it when it is replaced at end of life; an external device is connected through a breaker with a lead of whatever length the installation produces, is replaced without opening the panelboard, and is the arrangement used where the panelboard is existing or where the Owner standardizes on one device family across equipment of several makers. (11.1.3)

11.1.4 Where an integral surge protective device is furnished, it shall be installed by the panelboard manufacturer under the UL 67 listing, shall be connected to the bus on the load side of the main device, and shall be disconnectable for replacement without de-energizing the panelboard where the listing provides a disconnect for it.

11.1.5 Where an integral surge protective device is furnished, the device status indication shall be visible with the door closed.

11.2 Metering Provisions

11.2.1 The metering furnished within the panelboard shall be as indicated in the datasheet.

Metering Provisionsselect

No metering

Current transformer and meter mounting provisions only

Main metering

Main and branch-circuit metering

11.2.2 Meters, their accuracy class, their current transformers, and their communications shall comply with Electrical Power MonitoringElectrical Power Monitoring and MeteringResolves to the current edition.sync/electrical-power-monitoring, and where metering is furnished within the cabinet it shall be installed by the manufacturer under the UL 67 listing in a compartment separate from the wiring gutters.

NOTE Branch-circuit metering makes the energy of each circuit visible for tenant billing, commissioning, and measurement and verification, at the cost of a current transformer on every circuit and a meter that can read them; main metering records the panelboard as one load; mounting provisions leave the compartment and the current transformer space in place for a meter bought later. (11.2.3)

11.2.4 Where Adopted Energy CodeAdopted Energy CodeParameterEach project supplies its own value.adopted-energy-code requires the loads served from the panelboard to be submetered, the metering shall accumulate energy for those loads and shall report it to the building energy monitoring system under Electrical Power MonitoringElectrical Power Monitoring and MeteringResolves to the current edition.sync/electrical-power-monitoring.

12 Identification

12.1 Nameplates, circuit directories, arc-flash labels, and field markings shall comply with Electrical IdentificationElectrical IdentificationResolves to the current edition.sync/electrical-identification for material, lettering, attachment, and directory format.

12.2 Each panelboard shall carry a nameplate stating the panelboard designation, the system voltage with the number of phases and wires, the main bus rating, the main device rating where one is furnished, the assembly short-circuit current rating, and the source that feeds it, in the text listed on the nameplate schedule.

12.3 The panelboard designation on the nameplate shall match the designation on the panel schedule and on the one-line diagram.

12.4 The manufacturer shall mark on the interior the UL 67 listing, the series-rated combinations where series rating is the basis, and the devices listed for installation in the interior.

12.5 The available fault current at the line terminals and the date it was calculated shall be field-marked on each panelboard that is service equipment, in accordance with NFPA 70 110.24.

12.6 The arc-flash warning label shall carry the values established under Arc Flash StudyArc-Flash Hazard AnalysisResolves to the current edition.sync/arc-flash-study for the panelboard and shall be placed so that it is read before the door is opened, in accordance with NFPA 70 110.16.

12.7 Where the panelboard serves an emergency, legally required standby, or critical operations power system, it shall be marked as a component of that system in accordance with the article of NFPA 70 that governs the system.

13 Testing

13.1 Factory Tests

13.1.1 The manufacturer shall perform the production tests of UL 67 and NEMA PB 1 on every panelboard before shipment, including a dielectric withstand test of the bus, a mechanical operation check of every device, an inspection of every bus joint against the listed torque, and an inspection of the assembly against the reviewed shop drawings.

13.1.2 Factory test witnessing shall be as indicated in the datasheet.

Factory Test Witnessingradio

○ Witnessed by the Owner's representative

● Certified test report without witnessing

13.1.3 Where witnessing is selected, the manufacturer shall give not less than two weeks' notice of test readiness, shall submit the test procedure for review before the test, and shall not ship a panelboard until the witness has accepted the results or has waived attendance in writing.

NOTE A witnessed test lets the Owner see every device operate before the panelboard ships, and it commits a representative to a trip to the factory for each shipment; a certified report records the same tests without the trip, and leaves any discrepancy to be found at field acceptance testing. (13.1.4)

13.2 Field Acceptance Tests

13.2.1 Field acceptance tests shall be performed on every panelboard after installation is complete and before it is energized, in accordance with ANSI/NETA ATS and Electrical Acceptance TestingElectrical Acceptance TestingResolves to the current edition.sync/electrical-acceptance-testing, and shall include the tests indicated in the datasheet.

Field Acceptance Testscheckbox

☑ Visual and mechanical inspection including anchorage, nameplate, clearances, and filler plates

☑ Bolted connection torque verification against the manufacturer's values, with the applied values recorded

☑ Insulation resistance of each phase bus and the neutral bus, phase-to-phase and phase-to-ground

☐ Contact resistance of the main bus joints and the line terminations

☑ Operation of every device through one open and close cycle

☐ Ground-fault protection of equipment performance test by primary current injection

☐ Trip unit settings verification against the coordination study

☐ Shunt trip and accessory operation from the initiating device

☑ Neutral-to-ground separation verification on every panelboard that is not service equipment

☑ Branch circuit continuity and phase assignment against the record panel schedule

13.2.2 Insulation resistance shall be measured for one minute at 500 V DC on a system rated 250 V and below and at 1000 V DC on a system rated above 250 V, and a reading below the minimum ANSI/NETA ATS states for the voltage class shall be investigated before the panelboard is energized.

13.2.3 A panelboard that fails a field acceptance test shall not be energized, the Contractor shall report the failure to the Engineer of Record within one working day with the measured values, and the cost of the correction and of every repeated test shall be borne by the Contractor.

13.2.4 Infrared thermographic inspection shall be as indicated in the datasheet.

Infrared Thermographic Inspectionselect

Not required

One inspection within 90 days of energization

One inspection within 90 days of energization and a second at eleven months

13.2.5 Where infrared inspection is indicated, it shall be performed with the panelboard carrying not less than 40% of its rated load on each scanned connection, and every connection showing a rise of more than 10 °C above its neighbors shall be reported and corrected.

NOTE A second inspection near the end of the first year finds the termination that loosened through the first full cycle of seasonal load, which the first inspection cannot see; it costs a second visit under load and a warranty claim filed before the warranty ends. (13.2.6)

14 Installation

14.1 Location and Working Space

14.1.1 The panelboard shall be installed at the location and in the orientation indicated on the electrical plans, and its room shall satisfy Electrical RoomsElectrical RoomsResolves to the current edition.sync/electrical-rooms where it is installed in an electrical room.

14.1.2 Working space in front of the panelboard shall comply with NFPA 70 110.26 for the system voltage and the condition of the space, and the door swing shall not reduce that space.

14.1.3 The dedicated electrical space above the panelboard required by NFPA 70 110.26(E) shall be kept clear of piping, ductwork, and equipment not associated with the electrical installation.

14.1.4 Working space shall not be used for storage at any time.

14.1.5 A panelboard shall not be installed in a clothes closet, in a bathroom of a dwelling unit, dormitory, or guest room, or over the steps of a stairway, in accordance with NFPA 70 240.24(D), (E), and (F).

14.1.6 A floor-standing panelboard shall be set on a concrete housekeeping pad constructed under Concrete PadsConcrete Equipment PadsResolves to the current edition.sync/concrete-pads, extending not less than 3 in. beyond the cabinet on every side and not less than 4 in. above the finished floor indoors or 6 in. above finished grade outdoors, and shall be anchored as indicated on the seismic anchorage details.

14.1.7 Where seismic certification is required, the anchorage shall be that on which the certification depends, and a substitute anchor shall not be used without the manufacturer's written confirmation that the certification remains valid.

14.2 Mounting Height

14.2.1 The height from the finished floor to the top of a wall-mounted panelboard shall be as indicated in the datasheet.

Top-of-Panelboard Mounting Heightrange

in.

4878

Per drawings — the electrical details

14.2.2 Where several panelboards stand in a row, their tops shall align unless the installation conditions require otherwise.

14.2.3 No device handle in the panelboard shall be installed with the center of its grip more than 6 ft 7 in. above the floor or working platform, in accordance with NFPA 70 240.24(A).

NOTE The handle height limit is a reach requirement rather than a mounting convention: a tall panelboard set to a comfortable top height can still put its uppermost handle past the limit, which is why the handle height is verified separately from the mounting height. (14.2.4)

14.2.5 A wall-mounted panelboard shall be anchored to the structure at not fewer than four points with fasteners engaging studs, masonry anchors, or structural backing, and a flush-mounted cabinet shall be secured to the rough opening framing so that the front sits flush with the finished wall.

14.2.6 A panelboard shall be installed plumb and level, and the interior shall be aligned in the cabinet so that the front trim fits without forcing.

14.3 Conductor Terminations

14.3.1 The main lugs and the feed-through lugs shall be of the type indicated in the datasheet.

Main and Feed-Through Lug Typeradio

○ Mechanical set-screw lugs

○ Compression lugs

Manufacturer's standard (by default)

14.3.2 The manufacturer shall state the lug type furnished in the product data.

NOTE Mechanical lugs accept a range of conductor sizes and are the lugs the panelboard ships with; compression lugs are crimped to one conductor size with a tool matched to the lug, hold their pressure without re-torquing, and are used where the Owner's practice or the conductor material calls for them. (14.3.3)

14.3.4 Every lug shall be listed for the conductor material and size terminated in it, shall be rated for 75 °C conductors, and where aluminum conductors are terminated shall be listed for aluminum and the conductor prepared as the lug listing requires.

14.3.5 Every conductor termination shall be torqued to the device manufacturer's published value with a calibrated torque tool, and the values applied shall be recorded in the field test report.

14.3.6 A terminal shall carry one conductor unless the terminal is listed for more than one.

14.3.7 Conductors within the cabinet shall be trained and bundled so that each circuit can be identified and reached without disturbing its neighbors, shall not cross the bus, and shall not rest on a device.

14.3.8 Conductor selection and installation shall comply with Conductors And CablesConductors and CablesResolves to the current edition.sync/conductors-and-cables, and raceways shall comply with Raceways And ConduitRaceways and ConduitResolves to the current edition.sync/raceways-and-conduit.

14.4 Circuit Balancing

14.4.1 Branch circuits shall be assigned across the phases so that, at the connected load used for the panel schedule, the load on any phase does not deviate from the average phase load by more than the tolerance indicated in the datasheet.

Maximum Phase Load Imbalancerange

%

525

14.4.2 Where a tolerance is not selected in the datasheet, or where the tolerance cannot be met because of the fixed characteristics of the connected equipment, the Engineer of Record shall determine the acceptable phase assignment.

NOTE An unbalanced panelboard drives neutral current, unequal voltage drop between phases, and heating in the transformer and the feeder ahead of it; balancing costs nothing at the panel-schedule stage and is expensive to correct after the circuits are pulled. (14.4.3)

14.4.4 The final phase assignment of every branch circuit shall be recorded on the record panel schedule.

15 Delivery, Storage, and Handling

15.1 Each panelboard shall be delivered in the manufacturer's packaging with the listing marks and the nameplate intact, and shall be inspected for shipping damage at receipt.

15.2 Panelboards shall be stored indoors in a clean, dry space where the temperature is held above the dew point, and where indoor storage is not available they shall be stored under cover on pallets, off the ground, and protected from condensation, precipitation, dust, and physical damage.

15.3 Where a panelboard will stand more than 30 days in an unconditioned space before energization, its space heater, where furnished, shall be energized from a temporary source, or the cabinet shall otherwise be protected from condensation.

15.4 The interior shall remain in its packaging or covered until the branch circuit conductors are pulled, so that construction dust does not settle on the bus and the device terminals.

15.5 A panelboard damaged or wetted in transit, in storage, or in handling shall be repaired or replaced as the manufacturer directs and as the Engineer of Record accepts in writing.

16 Warranty

16.1 The manufacturer shall warrant each panelboard, its bus, and every factory-installed device against defects in materials and workmanship for the period indicated in the datasheet.

Manufacturer's Warranty Periodrange

years

1235

16.2 Where a warranty period is not selected in the datasheet, the manufacturer's standard warranty shall apply, and its term shall be stated in the product data.

16.3 The warranty period shall commence on the date indicated in the datasheet.

Warranty Commencementselect

Date of substantial completion

Date of energization

Date of shipment

NOTE Warranty commencement at shipment is the manufacturer's usual term, and it consumes the warranty during storage and construction; commencement at energization or substantial completion moves the coverage to the period the Owner is operating the equipment, and the manufacturer prices the added months into the panelboard. (16.4)

16.5 The warranty coverage scope shall be as indicated in the datasheet.

Warranty Coverage Scoperadio

○ Parts only

○ Parts and labor

16.6 The Contractor shall warrant the installation, including every termination, the anchorage, and the field-installed accessories, for the project warranty period.

16.7 A device or interior replaced under warranty shall be warranted for the remainder of the original period or for one year from the date of replacement, whichever ends later, and the replacement shall not reduce the coverage of any other device in the panelboard.

17 Spare Parts

17.1 The Contractor shall deliver the spare parts indicated in the datasheet to the Owner before the panelboards are accepted, and shall obtain a signed receipt for them.

Spare Parts to Be Furnishedcheckbox

☐ Two spare single-pole breakers of each trip rating installed

☐ One spare multi-pole breaker of each pole count and trip rating installed

☐ One spare ground-fault or arc-fault breaker of each type installed

☑ One set of filler plates for every space position on the project

☐ One set of fuses of each type and rating installed

17.2 Spare devices shall be identical to and interchangeable with the installed devices, shall be delivered in their original packaging, and shall be labeled with the panelboard designation or the device rating they serve.

17.3 Spare devices shall be stored in a labeled container in the electrical room, and shall not be stored inside an operating panelboard.