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SynC · Historical revision

Panelboards

Revision3
EditedAug 26, 2026
StatusSuperseded

View changes in this revision   Revision history

Historical revision. This is editorial revision 3, kept so citations to it stay resolvable. It is not the current text of this standard — see the current revision.

SynC Standards Team — Specifier (Platform Standards) ✓ OfficialDiscloses employment SynC (SynC Platform Team)
Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs

1 Scope

NOTE This standard covers the materials, construction, ratings, installation, testing, and identification requirements for dead-front panelboards rated 1000 V or less, including lighting and appliance branch-circuit panelboards and power distribution panelboards. (1.1)
NOTE A panelboard is a single panel or group of panel units designed for assembly in the form of a single panel, installed in a cabinet or cutout box and accessible only from the front, that includes buses and overcurrent devices for the control of light, heat, or power circuits. Dead-front construction leaves no energized part on the operating face once the trim is installed. (1.2)
NOTE Panelboards are by definition equipment rated 1000 V or less under NFPA 70 Article 408 and UL 67, so no separate low-voltage qualifier is carried in the title or the scope. (1.3)
1.4 Equipment shall comply with UL 67 (Panelboards), shall be listed and labeled by a Nationally Recognized Testing Laboratory (NRTL), and shall be installed in accordance with NFPA 70 Articles 110, 230, 240, 408, and all applicable articles governing the connected loads.

1.5 Assemblies Covered

NOTE Panelboards covered by this standard are dead-front assemblies with an enclosed bus structure and individual branch circuit overcurrent protective devices installed or provided for installation by the Contractor. (1.5.1)
NOTE They serve the function of subdividing a feeder or service into branch circuits, providing overcurrent protection for each branch circuit, and in main breaker configurations, providing a means of simultaneously disconnecting all ungrounded supply conductors. (1.5.2)
NOTE The terms "lighting and appliance branch-circuit panelboard" and "power panelboard", and the associated limit of 42 overcurrent devices in a single cabinet, were removed from NFPA 70 Article 408 in the 2008 edition. The terms remain in common usage and appear in older project documents, but they no longer carry code consequences and are not used as a basis for any requirement in this standard. (1.5.3)
1.5.4 For assemblies employing drawout power circuit breakers and designed for higher fault duty, see Low Voltage SwitchgearLow Voltage SwitchgearResolves to the current edition.sync/low-voltage-switchgear.
1.5.5 For assemblies designed as distribution switchboards with higher bus ratings and front-accessible wiring troughs, see Low Voltage SwitchboardsLow Voltage SwitchboardsResolves to the current edition.sync/low-voltage-switchboards.
1.5.6 For enclosed safety switches, fused disconnects, and non-automatic disconnecting means, see Enclosed Switches And DisconnectsEnclosed Switches and DisconnectsResolves to the current edition.sync/enclosed-switches-and-disconnects.
NOTE Residential-grade load centers, tested to the consumer-product provisions of UL 67 and supplied as dwelling-unit service and distribution equipment, are outside the scope of this standard. (1.5.7)
1.6.1 Service entrance equipment and downstream panelboards shall be grounded and bonded per Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current edition.sync/grounding-and-bonding.
1.6.2 Feeder and branch circuit conductors shall comply with Conductors And CablesConductors and CablesResolves to the current edition.sync/conductors-and-cables.
1.6.3 Raceways and conduit systems entering panelboards shall comply with Raceways And ConduitRaceways and ConduitResolves to the current edition.sync/raceways-and-conduit.

2 Referenced Standards

2.1 Equipment, materials, and installation shall comply with the latest adopted edition of the following standards and codes.
2.2 Where conflicts exist between referenced standards, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
NOTE The adopted edition of the National Electrical Code varies by jurisdiction; the edition enforced by the Authority Having Jurisdiction is the one that governs, and confirming it before fabrication avoids building to a superseded article number. (2.3)
Standard Title
NFPA 70 National Electrical Code (Articles 100, 110, 210, 215, 220, 225, 230, 240, 250, 285, 408, 700)
NFPA 70E Standard for Electrical Safety in the Workplace
UL 67 Standard for Panelboards
UL 50 Standard for Enclosures for Electrical Equipment (Non-Environmental Considerations)
UL 50E Standard for Enclosures for Electrical Equipment (Environmental Considerations)
UL 489 Standard for Molded-Case Circuit Breakers, Molded-Case Switches, and Circuit-Breaker Enclosures
UL 1053 Standard for Ground-Fault Sensing and Relaying Equipment
UL 1699 Standard for Arc-Fault Circuit-Interrupters
UL 943 Standard for Ground-Fault Circuit-Interrupters
UL 1449 Standard for Surge Protective Devices
NEMA PB 1 Panelboards
NEMA PB 1.1 General Instructions for Proper Installation, Operation and Maintenance of Panelboards Rated 1000V or Less
NEMA 250 Enclosures for Electrical Equipment (1,000 Volts Maximum)
NEMA AB 1 Molded Case Circuit Breakers, Molded Case Switches and Circuit Breaker Enclosures
NETA ATS Acceptance Testing Specifications for Electrical Power Equipment and Systems
IEEE 1584 Guide for Performing Arc-Flash Hazard Calculations
IEEE 519 Recommended Practice for Harmonic Control in Electric Power Systems

3 Submittals

3.1 Action Submittals

3.1.1 Contractor shall submit the following for Engineer's review and approval prior to procurement:
  • Shop drawings for each panelboard showing enclosure dimensions (height, width, depth), front elevation indicating device positions, bus configuration, and conduit entry areas
  • Panel schedules for each panelboard, including circuit numbers, circuit descriptions, pole counts, breaker frame sizes, trip ratings, and bus rating
  • Catalog data sheets or product data for the panelboard assembly and all overcurrent protective devices, including AFCI and GFCI breakers where specified
  • Catalog data confirming UL 67 listing and, for service entrance equipment, UL 67 service entrance listing
  • Short-circuit current rating (SCCR) documentation confirming that the assembly rating equals or exceeds available fault current at the point of installation
  • Where series ratings are applied per NEC 240.86, documentation of the tested series combination, including the upstream device type and rating
  • Surge protective device (SPD) product data where SPDs are factory-installed or provided for field installation
  • Seismic certification documentation where required by the applicable building code
  • Selective coordination study sealed by a registered professional engineer, where the panelboard serves an emergency, legally required standby, or critical operations power system
  • Arc flash incident-energy calculations performed in accordance with IEEE 1584, where an arc flash study is required by the Owner or the Authority Having Jurisdiction
Submittal Documentationcheckbox
☑ Shop drawings (dimensions, front elevation, conduit entry)
☑ Panel schedules (all circuits, ratings, descriptions)
☑ Product data / catalog sheets
☑ UL 67 listing confirmation
☑ SCCR documentation
☑ Series rating documentation (if applicable)
☑ SPD product data (if applicable)
☑ Seismic certification (if required)
☑ Selective coordination study, PE-sealed (if required)
☑ Arc flash incident-energy study per IEEE 1584 (if required)
3.1.2 Panelboard fabrication shall not begin and materials shall not be ordered until submittals are returned as reviewed.

3.2 Closeout Submittals

3.2.1 Contractor shall provide at substantial completion:
  • Record panel schedules reflecting all as-installed circuit assignments, updated to reflect any field changes from the contract documents
  • Operation and maintenance manuals for the panelboard assembly and installed accessories
  • Factory test reports (where witnessed or certified testing is specified)
  • Field acceptance test reports
  • Warranty documentation
  • Spare parts inventory with manufacturer part numbers
Required Closeout Submittalscheckbox
☑ Record panel schedules (as-installed circuit assignments)
☑ Operation and maintenance manuals
☑ Factory test reports
☑ Field acceptance test reports
☑ Warranty documentation
☑ Spare parts inventory with manufacturer part numbers

4 Quality Assurance

4.1 Manufacturer Qualifications

4.1.1 Panelboards shall be manufactured by a company with documented experience producing UL 67 listed panelboard assemblies.
4.1.2 The bus structure, interior assembly, and overcurrent protective devices shall be produced or furnished by the panelboard manufacturer as a coordinated assembly.
4.1.3 Field assembly of panelboards from separately sourced bus structures, enclosures, and breakers by the Contractor is not acceptable unless specifically authorized by the Engineer.
4.1.4 Manufacturer shall maintain a technical service organization capable of providing field support and replacement parts.

4.2 Source Limitations

4.2.1 All panelboards of a given type on a single project shall be from one manufacturer to ensure spare parts interchangeability, consistent training requirements, and coordinated technical support.
4.2.2 Mixing manufacturers for the same panelboard product category within a project requires written approval by the Engineer.

4.3 Installer Qualifications

4.3.1 Panelboard installation shall be performed by a licensed electrical contractor and journeyman-level electricians experienced in the installation of low voltage distribution equipment.
4.3.2 Personnel performing field acceptance testing shall be employed by a firm regularly engaged in testing electrical power equipment, with testing technicians certified at a minimum to NETA Level II.

4.4 Regulatory Requirements

4.4.1 Panelboards and their installation shall comply with all applicable federal, state, and local codes and ordinances, including the adopted edition of NFPA 70 and any state or local amendments.
4.4.2 The Authority Having Jurisdiction (AHJ) shall be notified of work as required and all work shall be subject to inspection by the AHJ.
4.4.3 Obtain all required permits prior to beginning installation.
4.4.4 Field modifications that alter the panelboard listing, including cutting additional openings in a NEMA 3R, 4, 4X, or 12 enclosure and installing components not listed for the assembly, are prohibited.
NOTE A field modification that voids the listing removes the basis on which the Authority Having Jurisdiction accepts the equipment, and the resulting rework is invariably charged to the party that made the cut. (4.4.5)

5 Environmental and Service Conditions

5.1 Panelboards shall be suitable for continuous operation under the ambient conditions at the installation site.
5.2 Where site conditions differ from standard rating conditions, equipment shall be derated per the manufacturer's published derating tables.

5.3 Ambient Temperature

5.3.1 The design maximum ambient temperature at the installation shall be as indicated in the datasheet.
Ambient Temperature (Maximum)range
°C
405055
5.3.2 Standard UL 67 temperature rise tests are conducted at 40°C ambient.
5.3.3 Equipment installed in locations with sustained ambient temperatures above 40°C shall be derated or an oversized assembly shall be specified.
NOTE Common elevated-temperature locations include rooftop mechanical rooms, non-air-conditioned warehouses, and equipment rooms in hot climates. (5.3.4)

5.4 Altitude

5.4.1 The installation altitude shall be as indicated in the datasheet.
Installation Altitudeselect
Below 6,600 ft (2,000 m) — No derating required
6,600 – 9,900 ft (2,000 – 3,000 m) — Derating required, consult manufacturer
Above 9,900 ft (3,000 m) — Special design required
NOTE At altitudes above 6,600 ft (2,000 m), reduced air density decreases the dielectric strength of air and impairs the cooling of enclosed equipment. (5.4.2)
5.4.3 Derating requirements shall be obtained from the manufacturer and documented on the contract drawings.

5.5 Installation Environment

5.5.1 The location of each panelboard shall be as indicated on the electrical plans.
NOTE The installation environment is drawing information rather than a product decision; the product decision it drives — the enclosure NEMA rating — is specified in the Enclosure section. (5.5.2)

5.6 Seismic Requirements

5.6.1 The seismic certification basis shall be as indicated in the datasheet.
Seismic Certificationselect
Not required
IBC/ASCE 7 — Importance Factor 1.0
IBC/ASCE 7 — Importance Factor 1.5 (essential facility)
OSHPD pre-approval required (California healthcare)
Per drawings — structural drawings (deferred by default)
NOTE The Seismic Design Category and Importance Factor are established by the project's structural design; the electrical scope adopts them rather than setting them. (5.6.2)
5.6.3 Where required by the applicable building code (IBC, CBC, or state-adopted equivalent), panelboards shall be seismically certified for the project's Seismic Design Category.
5.6.4 Seismic certification shall be by shake-table test or by analysis per ASCE 7.
5.6.5 Seismic anchorage details shall be included in the shop drawing submittals and shall be coordinated with the structural drawings.
5.6.6 Anchor bolts, housekeeping pad dimensions, and seismic restraints shall be installed per the manufacturer's certified installation instructions.

6 Electrical Ratings

6.1 System Voltage

6.1.1 The system voltage and configuration shall be as indicated in the datasheet.
System Voltageselect
120/240V 1Φ 3-wire
120/208V 3Φ 4-wire
277/480V 3Φ 4-wire
480V 3Φ 3-wire
120/240V 3Φ 4-wire (delta, center-tapped)
Per drawings — panel schedule (deferred by default)
NOTE The number of phases and the number of wires are fixed by the system voltage selected, so they are not offered as separate selections. (6.1.2)
6.1.3 The system voltage shall match the serving feeder or service voltage.
6.1.4 Where the panelboard is fed from a transformer secondary, verify that the panelboard voltage rating matches the transformer secondary voltage configuration.
6.1.5 Consult the Engineer when 480V delta systems or 120/240V center-tapped delta systems are encountered, as these systems have specific grounding and breaker requirements.

6.2 Main Bus Rating

6.2.1 Main bus continuous current rating shall be as indicated in the datasheet.
Main Bus Ampere Ratingrange
A
10012515020022525040060080010001200
Per drawings — panel schedule (deferred by default)
6.2.2 Bus rating shall be selected to carry the calculated demand load with adequate capacity for future circuit additions.
6.2.3 Bus rating shall not be less than the main overcurrent device rating.
NOTE Bus ratings of 225A are the most common configuration for commercial lighting and branch-circuit panelboards; power distribution panelboards serving large mechanical, elevator, or process loads typically require 400A to 1200A bus ratings. (6.2.4)
NOTE Ratings above 1200A are generally better served by switchboards or switchgear — see Low Voltage SwitchboardsLow Voltage SwitchboardsResolves to the current edition.sync/low-voltage-switchboards or Low Voltage SwitchgearLow Voltage SwitchgearResolves to the current edition.sync/low-voltage-switchgear. (6.2.5)

6.3 Short-Circuit Current Rating

6.3.1 The panelboard short-circuit current rating shall be as indicated in the datasheet.
Short-Circuit Current Rating (SCCR / AIC)range
kAIC
1014182225354265100
Per drawings — panel schedule (deferred by default)
6.3.2 The panelboard short-circuit current rating (SCCR), also called the available interrupting capacity (AIC) rating, shall equal or exceed the maximum available fault current at the panelboard line terminals.
6.3.3 Available fault current shall be determined by a short-circuit study based on confirmed utility available fault current, transformer impedance, and feeder conductor impedance.
6.3.4 The SCCR stamped on the assembly shall be the lowest-rated component in the assembly.
6.3.5 Fully-rated panelboards, where every breaker is individually rated for the assembly SCCR, are required at service entrance locations and at first-downstream distribution points where fault current is high.
6.3.6 Series-rated assemblies, where the combination of a higher-rated main breaker and lower-rated branch breakers is tested as a system, are permitted per NEC 240.86 at downstream locations where the available fault current at the panelboard terminals has been reduced by the impedance of the feeder.
NOTE Additional requirements for series-rated assemblies are addressed in the Series Rating section. (6.3.7)
NOTE A value of 22 kAIC is common for downstream 208V commercial branch-circuit panels; verify the available fault current at each panel location before selecting this rating. (6.3.8)

6.4 Service Entrance Equipment

6.4.1 Whether the panelboard is service entrance rated shall be as indicated in the datasheet.
Service Entrance Equipmentradio
○ Service entrance rated (main service panel)
○ Distribution panel (downstream of the service)
Per drawings — one-line diagram (deferred by default)
6.4.2 Where the panelboard serves as the building's main service entrance equipment, it shall be listed and labeled for use as service entrance equipment per UL 67 and shall comply with NFPA 70 Article 230, including provisions for service disconnecting means, service conductor terminations, metering socket (where utility-metered), and available fault current labeling.
6.4.3 Service entrance rated panelboards shall include a main bonding jumper connection point and, for services over 1,000A on solidly grounded wye systems of more than 150V to ground, ground fault protection of equipment (GFPE) per NEC 230.95.

7 Main Overcurrent Device

7.1 Main Breaker vs. Main Lugs Only

7.1.1 The main overcurrent device configuration shall be as indicated in the datasheet.
Main Overcurrent Device Configurationradio
○ Main circuit breaker (MCB)
○ Main lugs only (MLO)
Per drawings — panel schedule (deferred by default)
7.1.2 A main circuit breaker configuration is required when the panelboard serves as the building or tenant service disconnect, when a local means of simultaneously de-energizing all branch circuits is required for safety, and when the feeder overcurrent device is remote from the panelboard or is not readily accessible from the working space in front of the panel.
7.1.3 A main lug only (MLO) configuration is acceptable for panelboards that are sub-fed from a readily accessible overcurrent device that can be used as the disconnecting means, and for panelboards where NEC 408.36 permits omission of the main device.
7.1.4 MLO panelboards shall be fed from an overcurrent protective device sized per NEC 240.21 and protected for the bus rating of the panelboard.

7.2 Main Breaker Rating

7.2.1 Main breaker frame size and trip rating shall be as indicated in the datasheet.
Main Breaker Trip Ratingrange
A
7010012515017520022525030035040050060070080010001200
Per drawings — panel schedule (deferred by default)
7.2.2 The main breaker trip rating shall not exceed the bus ampere rating of the panelboard.
7.2.3 Where the feeder protective device is used as the sole overcurrent protection for the panelboard bus, the feeder device shall be sized not to exceed the bus ampere rating per NEC 408.36.

7.3 Main Breaker Type

7.3.1 The main breaker type shall be as indicated in the datasheet.
Main Breaker Typeselect
Thermal-magnetic (standard, fixed trip)
Electronic trip — adjustable long-time, instantaneous
Electronic trip — LSI (long-time, short-time, instantaneous)
Electronic trip — LSIG (long-time, short-time, instantaneous, ground fault)
NOTE Thermal-magnetic breakers are appropriate for standard commercial applications up to approximately 400A. (7.3.2)
7.3.3 Electronic trip units with adjustable settings provide greater coordination flexibility for larger main breakers and are preferred for main breakers 400A and above where selective coordination with upstream devices is required.
NOTE LSIG trip units include integral ground fault protection of equipment (GFPE) and satisfy NEC 230.95 requirements for services over 1,000A on qualifying systems without separate GFPE relay panels. (7.3.4)

7.4 Ground Fault Protection of Equipment (GFPE)

7.4.1 Where GFPE is required, the means of providing it shall be as indicated in the datasheet.
Ground Fault Protection of Equipment (GFPE)select
Not required — system voltage or disconnect rating below the NFPA 70 230.95 threshold
Integral to main breaker LSIG trip unit
Separate GFPE relay and sensor (UL 1053)
NOTE Whether GFPE is required at all is fixed by NFPA 70 230.95 from the system voltage and the disconnect rating; where the threshold is not reached the field records "Not required", and where it is, the means of providing it is the project selection. (7.4.2)
7.4.3 NFPA 70 Article 230.95 requires ground fault protection of equipment for solidly grounded wye services of more than 150V to ground (i.e., 277/480V systems) where the service disconnecting means is rated 1,000A or more.
7.4.4 GFPE shall operate to open all ungrounded service conductors when a ground fault current of 1,200A or more persists.
7.4.5 The maximum time delay before operation shall not exceed one second (60 cycles) for ground-fault currents of 3,000A or more.
7.4.6 GFPE shall be performance-tested after installation per NEC 230.95(C) using primary current injection.
7.4.7 Test procedures shall be submitted prior to testing.
NOTE GFPE is intended to protect equipment from the arcing damage caused by low-level ground faults that may not be cleared promptly by the main overcurrent device; it is not a substitute for personnel protection provided by GFCI devices on branch circuits. (7.4.8)

7.5 Arc Energy Reduction (NEC 240.87)

7.5.1 Where arc energy reduction is required, the method shall be as indicated in the datasheet.
Arc Energy Reduction Method (NEC 240.87)select
Not applicable — main breaker rated or adjusted below 1,200A
Zone-selective interlocking (ZSI)
Energy-reducing maintenance switch with local status indicator (ERMS)
Energy-reducing active arc flash mitigation system
Permanent instantaneous trip setting
Approved equivalent method per NEC 240.87(B)(6)
7.5.2 NEC 240.87 requires that where a circuit breaker is rated or adjusted to 1,200A or higher, a means shall be provided to reduce the clearing time of the circuit breaker and the energy available during a line-side arcing fault.
7.5.3 This requirement applies to the main breaker where its trip setting is 1,200A or more.
NOTE Zone-selective interlocking is the preferred method for panelboards because it reduces arc flash incident energy during maintenance without requiring mode changes, and it does not compromise normal selective coordination. (7.5.4)
7.5.5 The arc energy reduction method, the required documentation per NEC 240.87(A), and the performance test per NEC 240.87(C) shall be completed and submitted as part of the project closeout.

8 Physical Construction

8.1 Enclosure

8.1.1 Enclosure shall be a dead-front, metal-enclosed assembly, listed and labeled to UL 67, with the enclosure cabinet tested per UL 50 or UL 50E as appropriate for the installation environment.
8.1.2 Cabinet shall be fabricated from steel with galvanized interior components.
8.1.3 The enclosure NEMA rating shall be as indicated in the datasheet.
Enclosure NEMA Ratingselect
NEMA 1 — Indoor, general purpose (dry, climate-controlled)
NEMA 3R — Outdoor, rainproof (exposed or sheltered outdoor)
NEMA 4 — Watertight (indoor or outdoor, hose-directed water)
NEMA 4X — Watertight, corrosion-resistant (stainless steel or fiberglass)
NEMA 12 — Industrial dust-tight (indoor, no hose-down)
8.1.4 The mounting type shall be as indicated in the datasheet.
Mounting Typeradio
○ Surface-mounted (enclosure projects from wall)
○ Flush-mounted (trim flange at finished wall surface, box recessed)
○ Semi-flush-mounted (box partially recessed, trim overlapping the wall face)
○ Free-standing (floor-mounted)
Per drawings — panel schedule (deferred by default)
8.1.5 The enclosure finish color shall be as indicated in the datasheet.
Enclosure Finish Colortext
ANSI 61 gray
8.1.6 Door shall be hinged with a stainless steel piano hinge and shall be equipped with a combination lock and latch.
8.1.7 All panelboard door locks on a single project shall be keyed alike.
8.1.8 The front trim shall be of the dead-front type, concealing all energized parts and all overcurrent device line terminals when the door is open.
8.1.9 A directory cardholder with a transparent cover shall be mounted on the inside face of the door.
8.1.10 Single-door enclosures shall provide full-front access to all circuit breakers and trim.
8.1.11 The door shall be capable of being held open at 90 degrees without support, allowing hands-free operation.
NOTE NEMA 1 is the baseline for interior commercial electrical rooms, mechanical rooms, and utility spaces that are maintained dry and climate-controlled. (8.1.12)
8.1.13 NEMA 3R is required for all outdoor installations — panels mounted on building exteriors, in open parking structures, or on rooftops — and protects against rain, sleet, snow, and ice formation.
8.1.14 Wet and wash-down locations shall use a NEMA 4 or NEMA 4X enclosure.
8.1.15 NEMA 4X is required in food processing facilities, car wash equipment rooms, coastal or marine environments with significant salt air exposure, and chemical process areas.
8.1.16 The enclosure NEMA rating shall be consistent with the installation environment shown on the electrical plans.
8.1.17 Flush-mounted installations require that the wall construction accommodate the full enclosure depth plus clearance for conduit entries.
8.1.18 Coordinate with architectural drawings for wall type, thickness, and finished surface location.
8.1.19 Free-standing floor-mounted panelboards (typically 800A and above) shall be mounted on housekeeping pads per the Installation section.
8.1.20 Outdoor and wet location enclosures shall receive an enhanced coating system.
8.1.21 Where stainless steel enclosures are provided (NEMA 4X stainless), painted finish is not required on the enclosure exterior; interior surfaces may receive a corrosion-inhibiting coating.

8.2 Bus Assembly

8.2.1 The bus assembly shall be the panelboard manufacturer's standard design, factory-assembled and tested.
8.2.2 Main bus, branch circuit bus, and neutral bus shall be rated for the current, voltage, and fault current specified.
8.2.3 The main and branch bus material shall be as indicated in the datasheet.
Main and Branch Bus Materialradio
○ Copper
○ Aluminum (tin-plated)
8.2.4 The neutral bus rating shall be as indicated in the datasheet.
Neutral Bus Ratingselect
Not applicable (ungrounded or 2-wire system, no neutral)
100% of phase bus rating
50% of phase bus rating (reduced)
200% of phase bus rating (oversized for harmonic loads)
8.2.5 The ground bus shall be as indicated in the datasheet.
Ground Busradio
● Included — copper, sized per NEC 250
○ Included — copper, plus a separate isolated (insulated) ground bus for sensitive-equipment branch circuits
○ Not included (bonding via raceway or other listed means)
NOTE Copper bus provides higher conductivity per unit cross-section and lower contact resistance at bolted joints, and is the preferred selection for higher-ampere-rated panelboards and service entrance equipment. (8.2.6)
8.2.7 Aluminum bus is acceptable for standard commercial branch-circuit panelboards and offers weight savings in large assemblies; aluminum bus shall be tin-plated at all joint surfaces to prevent oxidation.
8.2.8 Bare aluminum bus is not acceptable.
8.2.9 Bus connections to copper terminals or other dissimilar metals shall use listed connectors rated for aluminum-to-copper connections.
NOTE A 100% neutral bus is appropriate for most commercial applications with a balanced mix of linear and nonlinear loads. (8.2.10)
8.2.11 A 50% neutral bus may be used only where the engineer has determined through harmonic analysis per IEEE 519 that third-harmonic and triplen-harmonic loading is minimal.
8.2.12 Where nonlinear single-phase loads (variable frequency drives, switching power supplies, LED drivers, data center UPS) represent a significant portion of the panel load, an oversized neutral bus rated 200% of the phase bus is required to carry the additive triplen harmonic currents that flow in the neutral without overheating.
8.2.13 A dedicated ground bus shall be included in all panelboards used as service entrance equipment and in all panelboards where equipment grounding conductors are present in the feeder or branch circuits.
8.2.14 The ground bus shall be insulated from the enclosure and neutral bus in all panelboards other than the service entrance panel where the main bonding jumper is located.
8.2.15 At the service entrance panel, the ground bus shall be bonded to the neutral bus and enclosure per NEC 250.
8.2.16 An isolated (insulated) equipment grounding bus shall be furnished only where isolated-ground branch circuits serving sensitive equipment are indicated.
NOTE An isolated ground bus is mounted on insulating standoffs so that the isolated grounding conductors return to the derived-system bonding point without picking up the enclosure's noise currents; furnishing one where no isolated-ground circuits exist adds cost and invites incorrect field terminations. (8.2.17)

8.3 Interior and Wiring Compartment

8.3.1 The number of branch circuit spaces (poles) shall be as indicated in the datasheet.
Number of Branch Circuit Spacesrange
poles
121820243036424854607284
Per drawings — panel schedule (deferred by default)
8.3.2 The space reserved for future circuits shall be as indicated in the datasheet.
Space Reservation for Future Circuitsselect
No spare spaces (all spaces populated)
2 spare single-pole spaces
4 spare single-pole spaces (10% spare minimum)
5% spare spaces
10% spare spaces
15% spare spaces
20% spare spaces
25% spare spaces
30% spare spaces
8.3.3 The interior shall provide separate wiring compartments so that supply conductors and branch circuit conductors do not occupy the same space as the bus assembly.
8.3.4 Wiring gutter spaces shall comply with NEC 312.6 for the conductor sizes and quantities being served.
8.3.5 Interior shall be arranged so that conductors can be installed and maintained without disturbing adjacent circuits.
8.3.6 Branch circuit breakers shall be arranged in a vertical column or two-column configuration.
8.3.8 Spaces designated as spare shall have blank filler plates installed in the trim and fully equipped bus stabs available for future breaker installation without internal modification.

8.4 Conduit Entry Areas

8.4.1 The primary conduit entry direction shall be as indicated in the datasheet.
Primary Conduit Entry Directionradio
○ Top entry (conduit enters from above)
○ Bottom entry (conduit enters from below)
○ Top and bottom (supply from top, branch circuits from bottom)
Per drawings — electrical plans (deferred by default)
8.4.2 Conduit entry areas shall be provided at top, bottom, and where required by the installation configuration, at sides.
8.4.3 Knockouts or concentric rings shall be provided at standard conduit trade sizes.
8.4.4 Where conduit enters from the top of a panelboard in a wet location, conduit entries shall be protected with conduit hubs listed for wet locations to prevent water infiltration.
8.4.5 Flush-mounted panelboards shall be furnished with the number of empty conduit stub-outs indicated in the datasheet, run from the panelboard gutter to an accessible location above an accessible ceiling and capped.
Flush-Mount Spare Conduit Stub-Outsrange
count
08
NOTE Once the wall is closed, a flush-mounted panelboard cannot accept a new circuit without demolishing finish work; stub-outs left at rough-in are the only economical path for future circuit extension, and the quantity is a judgment about how much future flexibility the Owner is buying. (8.4.6)

9 Overcurrent Protective Devices

9.1 Branch Circuit Breaker Type

9.1.1 All branch circuit breakers shall comply with UL 489.
9.1.2 Breakers shall be thermal-magnetic or electronic trip, rated for the voltage and frequency of the system.
9.1.3 The branch circuit breaker mounting type shall be as indicated in the datasheet.
Branch Circuit Breaker Mounting Typeradio
○ Bolt-on (mechanically secured to bus)
● Plug-on / plug-in (spring-clip engagement)
○ Plug-on neutral capable (plug-on with integral neutral connection)
9.1.4 The pole counts the interior shall accommodate are as indicated in the datasheet.
Branch Circuit Breaker Polescheckbox
☑ 1-pole (120V, 15A–30A branch circuits)
☑ 2-pole (240V or 2-phase 208V branch circuits)
☐ 3-pole (3-phase branch circuits)
9.1.5 Individual breaker frame sizes and trip ratings shall be as indicated in the datasheet.
Branch Circuit Breaker Trip Ratingstext
Enter value...
Per drawings — panel schedule (deferred by default)
9.1.6 Breakers shall be the panelboard manufacturer's listed breakers for the specific panelboard model to ensure proper engagement with the bus stabs and compliance with the assembly SCCR.
NOTE Bolt-on breakers provide a more positive mechanical and electrical connection to the bus and are the standard for industrial and higher-vibration environments and for power distribution panelboards. (9.1.7)
NOTE Plug-on breakers are the standard for commercial lighting and branch-circuit panelboards and offer faster installation and removal. (9.1.8)
NOTE Plug-on neutral (PON) capable interiors eliminate the need for a separate neutral pigtail from a GFCI or AFCI breaker to the neutral bus; the PON breaker connects directly to a neutral bus rail integral to the interior. (9.1.9)
9.1.10 Tandem (twin) breakers shall be installed only in panelboard positions specifically listed to accept them, and only where the resulting overcurrent device count does not exceed the number for which the panelboard is designed, rated, and listed per NEC 408.54.
NOTE A tandem breaker doubles the circuits in one space but does not raise the panelboard's listed device count; installing tandems in unlisted positions to squeeze in circuits is a common field expedient that fails inspection. (9.1.11)
9.1.12 All unassigned (spare) circuit spaces shall be equipped with listed filler plates; they shall not be left open.

9.2 AFCI and GFCI Protection

9.2.1 Arc-Fault Circuit-Interrupter (AFCI) Protection

9.2.1.1 The extent of AFCI branch circuit protection shall be as indicated in the datasheet.
AFCI Branch Circuit Breakersradio
○ Required at all 120V 15A and 20A branch circuits in this panel
○ Required at designated branch circuits
○ Not required
Per drawings — panel schedule (deferred by default)
9.2.1.2 NFPA 70 Section 210.12 requires combination-type AFCI protection on all 120V, single-phase, 15A and 20A branch circuits supplying outlets and devices in dwelling units, dormitories, hotel and motel guest rooms, and similar residential occupancies.
9.2.1.3 AFCI protection shall be provided by a listed combination-type AFCI circuit breaker installed at the panelboard origin of the branch circuit, or by listed outlet branch circuit AFCI protection at the first outlet in combination with a listed branch/feeder AFCI at the origin.
NOTE AFCI breakers detect both series arcing (damaged conductors) and parallel arcing (line-to-ground or line-to-neutral arcing faults) that would not be cleared by a standard thermal-magnetic breaker. (9.2.1.4)
9.2.1.5 For commercial occupancies where AFCI is not code-required, the Engineer may specify AFCI breakers in locations serving areas with high concentrations of plug loads or extension cords (open office areas, hotel convention areas) as a proactive fire prevention measure.

9.2.2 Ground-Fault Circuit-Interrupter (GFCI) Protection

9.2.2.1 The means of providing GFCI protection shall be as indicated in the datasheet.
GFCI Branch Circuit Breakers (at panelboard)radio
○ Provided at panelboard for all circuits requiring GFCI (GFCI breaker per circuit)
○ GFCI provided at point of use (GFCI receptacle or device, not at panelboard)
○ Combination AFCI/GFCI breakers at panelboard (dual-function)
Per drawings — panel schedule (deferred by default)
9.2.2.2 NFPA 70 Section 210.8 requires GFCI protection for personnel on all 125V through 250V receptacles supplied by single-phase branch circuits rated 150V or less to ground, in a broad range of locations including bathrooms, kitchens, garages, outdoors, unfinished basements, crawl spaces, boathouses, rooftops, and commercial kitchen areas.
9.2.2.3 GFCI protection shall be provided by a listed GFCI circuit breaker at the panelboard or by a listed GFCI receptacle at the first outlet.
NOTE GFCI breakers at the panelboard protect the entire branch circuit wiring as well as the connected devices and are preferred where the wiring method or installation environment creates a risk of insulation damage in the circuit conductors. (9.2.2.4)
NOTE GFCI protection at the panelboard is also more accessible for reset following a trip. (9.2.2.5)
NOTE Dual-function AFCI/GFCI combination breakers satisfy both requirements on a single pole and are particularly efficient in residential-type panelboards where many circuits require both types of protection. (9.2.2.6)

9.3 Series Rating

9.3.1 Series rating is permitted per NEC 240.86 where the combination of an upstream overcurrent device and a downstream branch circuit breaker has been tested as a series-rated combination by a testing laboratory.
NOTE Series rating allows lower-rated (and lower-cost) branch circuit breakers to be used downstream of a higher-rated main or feeder breaker in locations where the actual available fault current at the panel is less than the individual breaker interrupt rating would require. (9.3.2)
9.3.3 Series rating shall not be used at service entrance panels or at the first downstream distribution point after the utility service entrance, where fault current levels are highest.
9.3.4 Where series rating is applied, the panelboard shall be permanently and legibly marked with a warning label per NEC 110.22 identifying it as a series combination system and identifying the required replacement components.
9.3.5 Replacement of any overcurrent device in a series-rated assembly shall use only the same manufacturer, type, and rating as originally specified and listed in the tested combination.
NOTE Substitutions that appear equivalent but are not part of the tested combination break the series rating and render the assembly non-code-compliant. (9.3.6)

9.4 Selective Coordination

NOTE Selective coordination requires that only the overcurrent device immediately upstream of a fault opens, leaving every device further upstream closed so that unfaulted portions of the system stay energized. (9.4.1)
NOTE Selective coordination is mandated by NFPA 70 Articles 700, 701, and 708 for emergency, legally required standby, and critical operations power systems, where a cascading trip would extinguish egress lighting or drop life-safety loads. (9.4.2)
9.4.3 Where the panelboard serves an emergency, legally required standby, or critical operations power system, its overcurrent devices shall be selectively coordinated with all upstream and downstream overcurrent devices.
9.4.4 Selective coordination shall be demonstrated by a study that overlays the published time-current characteristic curves of the actual specified devices, including the instantaneous region.
NOTE Coordination cannot be inferred from ampere ratings alone; two devices two frame sizes apart may still overlap in the instantaneous region, which is where the vast majority of coordination failures occur. (9.4.5)
9.4.6 Series-rated combinations shall not be applied where selective coordination is required, because a series combination relies on both devices opening for a high-magnitude fault.

10 Surge Protective Devices

10.1 SPD Requirements

10.1.1 Whether a surge protective device is provided at the panelboard shall be as indicated in the datasheet.
Surge Protective Device (SPD)radio
● Provided
○ Not provided
10.1.2 The SPD type shall be as indicated in the datasheet.
SPD Typeradio
○ Type 1 — permanently connected on the line side of the main disconnect
● Type 2 — permanently connected on the load side of the main disconnect
○ Type 1+2 combination (line-side and load-side protection in one assembly)
10.1.3 The SPD mounting configuration shall be as indicated in the datasheet.
SPD Configurationradio
● Factory-installed, integral to the panelboard
○ Field-installed in a dedicated space within the panel
○ External, mounted adjacent to the panel
10.1.4 The SPD nominal discharge current rating shall be as indicated in the datasheet.
SPD Nominal Discharge Current Ratingrange
kA
10204080
NOTE Nominal discharge current ratings correspond to exposure: 10 kA suits standard commercial occupancies, 20 kA provides enhanced protection, 40 kA suits critical facilities such as data centers, and 80 kA suits high-exposure locations such as rooftop panels. (10.1.5)
10.1.6 NFPA 70 Section 230.67 requires a surge protective device (SPD) on all services supplying dwelling units, and Section 215.18 extends this requirement to feeder panelboards supplying the same occupancy types.
NOTE SPDs protect connected equipment from transient overvoltages caused by utility switching, lightning-induced surges on the distribution system, and load-switching transients within the building. (10.1.7)
NOTE Transient surge damage is cumulative; even surges that do not cause immediate failure degrade insulation and reduce equipment lifespan. (10.1.9)
10.1.10 Type 1 SPDs are listed to be installed ahead of the service disconnecting means and may be connected without an overcurrent device.
10.1.11 Type 2 SPDs are the standard for panelboards downstream of the service entrance and shall be connected per the manufacturer's instructions with an integral or external overcurrent protective device.
10.1.12 Only one of the two types is typically required at any given panel location; coordinate the placement of SPDs across the distribution system to avoid redundant or conflicting installations.
10.1.13 SPDs shall comply with UL 1449 (4th edition or current) and shall be listed for the system voltage and configuration.
10.1.14 The SPD shall include a status indicator (visible LED) showing device health, and shall include audible or dry-contact alarm output for remote monitoring where continuous operation is critical.
10.1.15 SPDs shall be connected as close as practicable to the bus, using the shortest possible lead lengths, to minimize the series inductance that reduces surge clamping effectiveness.

11 Metering and Monitoring

11.1 Metering at the panelboard shall be as indicated in the datasheet.
Metering at Panelboardselect
No metering
Metering provisions only (current transformer compartment; meter furnished separately)
Current-only monitoring (per-phase ammeter)
Multifunction digital panel meter (V, A, kW, kWh)
Revenue-grade energy meter (ANSI C12.1 Class 0.5)
11.2 Where a meter is provided, its communication protocol shall be as indicated in the datasheet.
Meter Communication Protocolselect
Not applicable — no meter provided
Modbus RTU (RS-485)
Modbus TCP/IP (Ethernet)
BACnet MS/TP
BACnet IP
11.3 Where submetering is required by the adopted energy code (ASHRAE 90.1 Section 8.4.3 or applicable state energy code), a meter capable of recording energy consumption (kWh) over time shall be provided with a communication interface for integration with the building management system or energy management platform.
11.4 Revenue-grade metering is required where energy data is used for tenant billing or utility interconnection purposes.

12 Identification and Circuit Directory

12.1 Circuit Directory

12.1.1 The circuit directory format shall be as indicated in the datasheet.
Circuit Directory Formatradio
● Typed and laminated (provided and installed by Contractor at closeout)
○ Computer-printed insert (provided in manufacturer's directory holder)
○ Machine-engraved on aluminum insert
12.1.2 Every panelboard shall have a circuit directory affixed to the inside of the door per NEC 408.4.
12.1.3 The circuit directory shall identify every circuit and every spare position by a clear, specific description of the load served.
12.1.4 Identification shall include the space or area served and the load type (e.g., "Suite 204 — Receptacles East Wall" or "AHU-3 — Compressor").
12.1.5 Generic descriptions such as "Spare," "Lights," or "Power" without specifying the area or load type do not comply with NEC 408.4 and are not acceptable.
12.1.6 Circuit directories shall be completed and installed prior to the final inspection.
12.1.7 The Contractor shall provide an updated circuit directory reflecting all as-installed circuit assignments as part of the record document submittals.
12.1.8 Handwritten circuit directories are not acceptable.
12.1.9 Where symbols or abbreviations are used to shorten circuit descriptions per NEC 408.4(A), a legend defining all symbols and abbreviations shall be included in the circuit directory.

12.2 Panel Nameplate

12.2.1 Manufacturer shall provide an engraved or machine-printed nameplate on the outside of the enclosure identifying:
  • Panel designation (matching the contract drawings and panel schedule)
  • System voltage and number of phases and wires
  • Bus ampere rating
  • Short-circuit current rating (SCCR/AIC)
  • Manufacturer name and catalog or order number
  • Date of manufacture
12.2.2 Each panelboard used as service equipment shall be field-marked with the maximum available fault current at its line terminals and the date the calculation was performed, per NEC 110.24, and the marking shall be updated whenever the supply is modified.
12.2.3 The panel nameplate material shall be as indicated in the datasheet.
Panel Nameplate Materialradio
● Laminated phenolic (indoor)
○ Stainless steel (outdoor or corrosive environment)
○ Aluminum (anodized)

12.3 Arc Flash Warning Label

12.3.1 Each panelboard shall receive an arc flash warning label per NFPA 70E and IEEE 1584, installed prior to energization.
12.3.2 The basis of the arc flash label shall be as indicated in the datasheet.
Arc Flash Analysisradio
○ Formal arc flash analysis (IEEE 1584) — label with incident energy and boundary
○ Generic warning label — no formal analysis performed
12.3.3 Where a formal arc flash hazard analysis has been performed for the project, labels shall include the incident energy in cal/cm², the arc flash boundary distance, the required personal protective equipment (PPE) category, and the date of the study.
12.3.4 Where no formal arc flash analysis has been performed, a generic warning label identifying the voltage class and requiring use of appropriate PPE shall be installed as a minimum.
NOTE The analysis enables selection of appropriate PPE, supports documentation of safe work procedures, and is increasingly required by insurance carriers and OSHA enforcement. (12.3.6)

13 Testing

13.1 Factory Tests

13.1.1 Panelboard assemblies shall be factory-tested per NEMA PB 1 and UL 67 production test requirements prior to shipment.
13.1.2 Factory tests shall include:
  • Dielectric withstand test on the bus assembly (hi-pot) per UL 67 requirements
  • Mechanical operation of all circuit breakers — each breaker shall be operated through at least one open/close cycle to verify free operation and proper engagement with the bus stabs
  • Bus assembly inspection — verify all bus joints are properly torqued, bus is fully insulated, and no loose components or foreign objects are present
  • Dimensional and visual inspection against the approved shop drawings
13.1.3 Each factory-installed surge protective device shall be functionally tested at the factory and its test record furnished before shipment.
13.1.4 The extent of factory acceptance testing shall be as indicated in the datasheet.
Factory Acceptance Testingradio
● Standard production tests (unwitnessed, with certified test report)
○ Witnessed factory test (owner or engineer representative present)
○ Not required beyond standard UL 67 production tests
13.1.6 The manufacturer shall provide a minimum of two weeks' advance notice of test readiness and shall submit test procedures for review before testing.

13.2 Field Acceptance Tests

13.2.1 NETA ATS acceptance testing for panelboards shall include as a minimum:
  • Visual and mechanical inspection of the enclosure, bus assembly, breaker engagement, nameplate data, wiring connections, and clearances
  • Insulation resistance test on each phase bus, neutral bus, and each individual branch circuit (phase-to-phase and phase-to-ground, minimum 1 minute at 500VDC for systems below 300V and 1,000VDC for systems 300V through 1000V)
  • Contact resistance measurement on main bus joints and supply conductor terminations (microohmmeter)
  • Operational test of each circuit breaker — mechanical and electrical (trip coil, if provided)
  • Functional test of GFPE relay system per NEC 230.95(C) by primary current injection (where GFPE is installed)
  • Verification of neutral-to-ground separation in all non-service-entrance panels
  • Verification that all unused circuit spaces have filler plates and that bus stabs are not exposed
  • Circuit continuity check on each installed branch circuit
  • Verification of arc flash labels and circuit directory completeness
  • Torque verification of each accessible bolted bus joint and terminal lug against the manufacturer's published value, with the applied values recorded
Field Acceptance Tests Requiredcheckbox
☑ Visual and mechanical inspection
☑ Insulation resistance test
☑ Contact resistance measurement (microohmmeter)
☑ Torque verification with recorded values
☑ Operational test of each circuit breaker
☐ GFPE functional test by primary current injection
☑ Neutral-to-ground separation verification
☑ Filler plate and exposed bus stab verification
☑ Branch circuit continuity check
☑ Arc flash label and circuit directory verification
13.2.2 Contractor shall engage a qualified independent testing firm to perform acceptance testing per NETA ATS after installation is complete and before the panelboard is energized under load.
13.2.3 The testing firm shall be regularly engaged in testing electrical power equipment, employing NETA-certified technicians.
13.2.4 Ground resistance and bonding continuity testing shall be performed per Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current edition.sync/grounding-and-bonding.

13.3 Performance Test — GFPE

13.3.1 Where ground fault protection of equipment is installed per NEC 230.95, the Contractor shall arrange for a performance test of the GFPE system upon completion of the installation and before the service is energized for normal operation.
13.3.2 The test shall be conducted by a qualified person using primary current injection equipment per the GFPE manufacturer's test instructions.
13.3.3 Test results, including the actual pickup current and time-delay values, shall be recorded and submitted as part of project closeout.

14 Installation

14.1 Working Clearances

Nominal Voltage Condition 1 (exposed on one side) Condition 2 (exposed on both sides) Condition 3 (exposed on both sides, energized equipment opposite)
0–150V 36 in. 36 in. 36 in.
151–1000V 36 in. 42 in. 48 in.
14.1.1 Minimum working space shall be maintained in front of panelboards per NFPA 70 Article 110.26.
14.1.2 The applicable working clearance condition shall be as indicated in the datasheet.
Working Clearance Conditionselect
Condition 1 — exposed energized parts on one side of the working space
Condition 2 — exposed energized parts on both sides
Condition 3 — energized equipment on the opposite side of the working space
Per drawings — electrical plans (deferred by default)
14.1.3 Working space depth shall be measured from the front of the live parts or the front of the enclosure, whichever is greater, to any obstruction.
14.1.4 Working space shall not be used for storage.
14.1.5 Dedicated electrical space above the panelboard to the structural ceiling (or 6 ft above the top of the panel, whichever is lower) shall be maintained per NEC 110.26(E).
14.1.6 This dedicated space shall not be penetrated by piping, ducts, or other non-electrical systems unless protected from drips or leaks.
14.1.7 Headroom in working spaces shall be a minimum of 6.5 ft or the height of the equipment, whichever is greater.

14.2 Mounting

14.2.1 The mounting height to the top of the panel shall be as indicated in the datasheet.
Mounting Height (to top of panel)range
in
4878
Default: 72 in
14.2.2 Panelboards shall be mounted plumb, level, and secure per manufacturer's installation instructions and NEMA PB 1.1.
14.2.3 Surface-mounted panelboards shall be anchored to the structural wall with minimum four fasteners engaging studs, masonry anchors, or structural backing.
14.2.4 Flush-mounted panelboards shall be secured to the rough opening framing or structural backing.
14.2.5 Where multiple panelboards are mounted in a row, the top of each panel shall be at a consistent height unless the installation conditions require otherwise.
14.2.6 The maximum height above the finished floor or working platform to the center of the grip of the highest operating handle shall be as indicated in the datasheet.
Maximum Operating Handle Height Above Finished Floorrange
in
4879
Default: 79 in
14.2.7 No overcurrent device operating handle shall be installed so that the center of its grip is more than 6 ft 7 in. (2.0 m) above the floor or working platform, per NEC 240.24(A).
NOTE The 6 ft 7 in. limit is a reach requirement, not a mounting convention: a tall panel set to a comfortable top-of-panel height can still push its uppermost handle past the limit, which is why the handle height is verified separately from the mounting height. (14.2.8)
14.2.9 Panelboards shall not be mounted in bathrooms, clothes closets, or above steps of a stairway per NEC 240.24(E) and (F).

14.3 Housekeeping Pads

14.3.1 Free-standing floor-mounted panelboards (typically 800A and above) shall be mounted on reinforced concrete housekeeping pads extending a minimum of 3 in. beyond the base of the enclosure on all sides.
14.3.2 Pads shall be a minimum of 3.5 in. above the finished floor for indoor installations and 4 in. above finished grade for outdoor installations to protect against water pooling and forklift damage.
14.3.3 Coordinate pad dimensions, anchor bolt locations, and conduit penetration locations with the panelboard shop drawings prior to concrete placement.
14.3.4 See Cast In Place ConcreteCast-in-Place ConcreteResolves to the current edition.sync/cast-in-place-concrete for housekeeping pad construction requirements.

14.4 Conduit Terminations and Conductor Connections

14.4.1 The main lug termination type shall be as indicated in the datasheet.
Main Lug Termination Typeradio
● Mechanical set-screw lugs (standard)
○ Compression (crimp) lugs (field-installed)
○ Bus bar extension lugs (large conductors, parallel sets)
14.4.2 Conduit entries shall comply with Raceways And ConduitRaceways and ConduitResolves to the current edition.sync/raceways-and-conduit.
14.4.3 All conduit penetrations into the panelboard enclosure shall be sealed where required by the installation conditions (wet locations, firestopping, rodent exclusion).
14.4.4 Conduit hubs listed for wet locations shall be used at all wet location panels.
14.4.5 Conductors shall comply with Conductors And CablesConductors and CablesResolves to the current edition.sync/conductors-and-cables and shall be installed per the conductor manufacturer's minimum bend radius requirements.
14.4.6 Supply conductors shall be terminated in the designated line-side terminal lugs and shall not share the terminal with other conductors unless the terminal is specifically listed for multiple conductors.
14.4.7 All conductor terminations shall be torqued to the manufacturer's published torque specifications using a calibrated torque wrench.
14.4.8 Torque values shall be recorded as part of the field test documentation.
14.4.9 Aluminum conductors shall use conductors listed for use with the terminal material; aluminum conductors shall be prepared with listed anti-oxidant compound prior to termination unless the terminal manufacturer's instructions indicate that preparation is not required.

14.5 Conductor Organization

14.5.1 Within the panelboard wiring compartment, conductors shall be neatly routed, supported, and organized so that each circuit can be individually identified and accessed without disturbing adjacent circuits.
14.5.2 Wire ties shall be used to bundle groups of conductors.
14.5.3 Conductors shall not cross energized bus.

14.6 Circuit Balancing

14.6.1 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
%
520
Default: 10 %
14.6.2 Where the indicated 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 panel drives neutral current, unequal voltage drop between phases, and premature transformer and conductor heating; balancing costs nothing at the panel-schedule stage and is expensive to correct after circuits are pulled. (14.6.3)
14.6.4 The final phase assignment of every branch circuit shall be recorded on the record panel schedule.

14.7 Outdoor Installation Requirements

14.7.1 Outdoor panelboards in NEMA 3R, 4, or 4X enclosures shall be installed with:
  • Conduit entries sealed at the enclosure with listed conduit hubs or fittings for wet locations, with all unused knockouts sealed
  • Conduit runs entering from the bottom of the enclosure where possible; conduit runs entering from the top shall have drip loops or conduit seals to prevent water migration
  • A rain-tight conduit hub or sealing fitting where conduit enters from top
  • All sealing requirements of Raceways And ConduitRaceways and ConduitResolves to the current edition.sync/raceways-and-conduit for wet location conduit runs
14.7.2 A sun shield and rain hood shall be provided as indicated in the datasheet.
Outdoor Panel Sun Shield / Weather Hoodradio
○ Required
● Not required
14.7.3 A sun shield and rain hood shall be provided on any outdoor panelboard in unshaded, full-sun exposure, where solar gain would drive the interior above the equipment's rated ambient.

14.8 Delivery, Storage, and Handling

14.8.1 Panelboards shall be delivered to the site in the manufacturer's original packaging, with all breakers, interior components, and trim protected from damage.
14.8.2 Equipment shall be inspected for damage upon delivery and any damage documented and reported to the manufacturer before installation.
14.8.3 Equipment shall be stored indoors in a clean, dry, climate-controlled location where possible.
14.8.4 Where indoor storage is not available, equipment shall be stored under cover on pallets, off the ground, and protected from moisture and construction debris.
14.8.5 Condensation heaters shall be connected and energized during storage in unheated environments if the ambient temperature may fall below the dew point, to prevent condensation on bus and insulators.

15 Warranty

15.1 The manufacturer shall warrant each panelboard for the period indicated in the datasheet.
Warranty Periodselect
1 year from date of substantial completion
2 years from date of substantial completion
3 years from date of substantial completion
5 years from date of substantial completion
15.2 The warranty coverage scope shall be as indicated in the datasheet.
Warranty Coverage Scoperadio
● Parts only
○ Parts and labor
15.3 Additional warranty services shall be provided as indicated in the datasheet.
Additional Warranty Servicescheckbox
☐ Emergency response (business hours)
☐ Emergency response (24/7)
☐ Annual preventive maintenance included
15.4 Warranty shall cover defects in materials and workmanship under normal conditions of use.
15.5 Warranty period shall begin at the date of substantial completion, not the date of shipment or installation.
15.6 The manufacturer shall maintain the capability to provide replacement parts for the panelboard assembly for a minimum of 10 years from the date of manufacture.

16 Spare Parts and Maintenance

16.1 Spare circuit breakers shall be furnished as indicated in the datasheet.
Spare Circuit Breakersradio
○ None
● Two spare of each pole count and trip rating installed
○ 10% of each circuit breaker type (minimum two)
16.2 Spare breakers shall be identical in manufacturer, type, pole count, frame size, and trip rating to the installed breakers.
16.3 Spare breakers shall be stored in a labeled enclosure or storage box in the electrical room, not inside the operating panel.

16.4 Additional Closeout Items

16.4.1 The Contractor shall provide the following additional items at substantial completion:
  • All blank filler plates for unused circuit positions (in addition to those installed in the panel)
  • One complete set of keys for all panelboard locks and padlocks
  • Printed or electronic copy of the panelboard manufacturer's installation, operation, and maintenance instructions

16.5 Ongoing Maintenance

16.5.1 Ongoing maintenance of installed panelboards shall be conducted per NEMA PB 1.1, which specifies inspection and torque re-check intervals.
16.5.2 Bus joint bolts shall be re-torqued at the first annual maintenance interval following energization, as thermal cycling during the first year of service may cause relaxation in bolted joints.