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Low Voltage Switchgear

Written and maintained by SynC.

Rev8
IssuedOct 17, 2026
LicenseCC BY 4.0
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1 Scope

NOTE This standard governs the switchgear as a listed assembly: the structure and its compartments, the bus and its supports, the drawout breakers and the cradles, shutters, and interlocks that hold them, the trip units and the control power that operates them, the relays, instrument transformers, meters, surge protection, and network devices built into the structure, and the field work that puts the switchgear into service. (1.1)
NOTE Low-voltage power circuit breaker switchgear is the assembly in which each breaker occupies a grounded metal compartment of its own, is withdrawn from the bus on rails without disturbing its neighbors, and is built to carry its short-circuit current for 30 cycles so that the breaker below it clears first. The compartments, the short-time rating, and the drawout construction are what the assembly buys over a switchboard, and they are also what it costs: a deeper structure, a larger footprint, and a higher price for every position. (1.2)
NOTE Four assembly standards divide low-voltage distribution equipment by construction and listing, and this one is the UL 1558 metal-enclosed power circuit breaker switchgear. Low Voltage SwitchboardsLow Voltage SwitchboardsResolves to the current adopted revision.sync/low-voltage-switchboards is the UL 891 dead-front switchboard built around molded-case, insulated-case, and fusible devices; PanelboardsPanelboardsResolves to the current adopted revision.sync/panelboards is the UL 67 cabinet whose branch devices subdivide one feeder; Motor Control CentersMotor Control CentersResolves to the current adopted revision.sync/motor-control-centers is the UL 845 lineup of starter cells on a shared vertical bus; Medium Voltage SwitchgearMedium Voltage SwitchgearResolves to the current adopted revision.sync/medium-voltage-switchgear is anything above 1000 V. (1.3)
NOTE Where this switchgear is the secondary of a unit substation under Secondary Unit SubstationsSecondary Unit SubstationsResolves to the current adopted revision.sync/secondary-unit-substations, or the construction basis of paralleling switchgear under Generator Paralleling SwitchgearGenerator Paralleling SwitchgearResolves to the current adopted revision.sync/generator-paralleling-switchgear, that standard invokes this one for the structure, the bus, the compartments, the breakers, and their trip units, and governs the ratings coordinated across the assembly, the connections between its sections, and the controls that make it a substation or a paralleling lineup. (1.4)
NOTE The switchgear is one listed product. Its short-circuit and short-time ratings, its seismic certification, and its arc-resistant rating are properties of the whole assembly in the configuration tested, and a breaker, a bus modification, or a compartment added outside that listing removes the switchgear from the condition under which it was rated. (1.5)
NOTE The following are governed elsewhere and are outside this standard: (1.6)
  • the utility point of delivery, the conductors from it, the meter socket, the utility's metering requirements, and the rules that apply where the switchgear is the first disconnecting means at the utility supply, under Electrical Service EntranceElectrical Service EntranceResolves to the current adopted revision.sync/electrical-service-entrance
  • the feeders that leave the switchgear and the conductors that enter it, and their terminations, under Conductors And CablesConductors and CablesResolves to the current adopted revision.sync/conductors-and-cables
  • the raceways entering the structure, under Raceways And ConduitRaceways and ConduitResolves to the current adopted revision.sync/raceways-and-conduit
  • the busway run, its supports, and its joints, under BuswayBuswayResolves to the current adopted revision.sync/busway
  • the wireway or auxiliary gutter trough that adjoins the structure, under Wireways And Auxiliary GuttersWireways and Auxiliary GuttersResolves to the current adopted revision.sync/wireways-and-auxiliary-gutters
  • 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 adopted revision.sync/grounding-and-bonding
  • 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 adopted revision.sync/surge-protective-devices
  • the meters, their accuracy class, their current sensors, and the monitoring system they report to, under Electrical Power MonitoringElectrical Power Monitoring and MeteringResolves to the current adopted revision.sync/electrical-power-monitoring
  • the station battery, its charger, and its DC distribution panel, under DC Battery SystemsDC Battery SystemsResolves to the current adopted revision.sync/dc-battery-systems
  • the transformer feeding the switchgear, under Medium Voltage TransformersMedium-Voltage Distribution TransformersResolves to the current adopted revision.sync/medium-voltage-transformers or Low Voltage Dry Type TransformersLow-Voltage Dry-Type TransformersResolves to the current adopted revision.sync/low-voltage-dry-type-transformers
  • the automatic transfer switch on either side of the switchgear, under Automatic Transfer SwitchesAutomatic Transfer SwitchesResolves to the current adopted revision.sync/automatic-transfer-switches
  • the short-circuit, coordination, and arc-flash studies, under Short Circuit StudyShort-Circuit StudyResolves to the current adopted revision.sync/short-circuit-study, Protective Coordination StudyProtective Device Coordination StudyResolves to the current adopted revision.sync/protective-coordination-study, and Arc Flash StudyArc-Flash StudyResolves to the current adopted revision.sync/arc-flash-study
  • the method, the criteria, the tester, and the report of the field acceptance tests this standard names, under Electrical Acceptance TestingElectrical Acceptance TestingResolves to the current adopted revision.sync/electrical-acceptance-testing
  • the room the switchgear occupies, under Electrical RoomsElectrical RoomsResolves to the current adopted revision.sync/electrical-rooms
  • the housekeeping pad the switchgear stands on, under Concrete PadsConcrete Equipment PadsResolves to the current adopted revision.sync/concrete-pads
1.7 Switchgear shall be listed and labeled to UL 1558 by a Nationally Recognized Testing Laboratory and shall comply with IEEE C37.20.1.
1.8 Every power circuit breaker in the switchgear shall comply with IEEE C37.13, shall carry the preferred ratings of IEEE C37.16, and shall be listed for use in the assembly.
1.9 The location and orientation of each switchgear lineup shall be as indicated on the electrical plans.
1.10 Where a value stated on the one-line diagram for a particular lineup differs from the datasheet selection under this standard, the one-line diagram shall govern for that lineup.

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 1558 Metal-Enclosed Low-Voltage Power Circuit Breaker Switchgear
UL 1066 Low-Voltage AC and DC Power Circuit Breakers Used in Enclosures
UL 891 Switchboards
UL 489 Molded-Case Circuit Breakers, Molded-Case Switches, and Circuit-Breaker Enclosures
UL 1053 Ground-Fault Sensing and Relaying Equipment
UL 1449 Surge Protective Devices
UL 50 Enclosures for Electrical Equipment, Non-Environmental Considerations
UL 50E Enclosures for Electrical Equipment, Environmental Considerations
IEEE C37.20.1 Metal-Enclosed Low-Voltage (1000 Vac and below, 3200 Vdc and below) Power Circuit Breaker Switchgear
IEEE C37.13 Low-Voltage AC Power Circuit Breakers Used in Enclosures
IEEE C37.16 Preferred Ratings, Related Requirements, and Application Recommendations for Low-Voltage AC and DC Power Circuit Breakers
IEEE C37.17 Trip Systems for Low-Voltage (1000 V and below) AC and General Purpose (1500 V and below) DC Power Circuit Breakers
IEEE C37.50 Test Procedures for Low-Voltage AC Power Circuit Breakers Used in Enclosures
IEEE C37.51 Conformance Test Procedure for Metal-Enclosed Low-Voltage AC Power-Circuit-Breaker Switchgear Assemblies
IEEE C37.20.7 Guide for Testing Switchgear Rated Up to 52 kV for Internal Arcing Faults
IEEE C37.90 Relays and Relay Systems Associated with Electric Power Apparatus
IEEE C37.90.1 Surge Withstand Capability Tests for Relays and Relay Systems Associated with Electric Power Apparatus
IEEE C57.13 Requirements for Instrument Transformers
IEEE 1584 Guide for Performing Arc-Flash Hazard Calculations
NEMA 250 Enclosures for Electrical Equipment (1000 Volts Maximum)
ANSI Z55.1 Gray Finishes for Industrial Apparatus and Equipment
NFPA 70 National Electrical Code (Articles 110, 215, 230, 240, 250, 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 switchgear is released for manufacture:
  • shop drawings for each lineup giving the front, side, and rear elevations, the section widths, depths, and heights, the compartment arrangement with each breaker position identified, the shipping splits, the weight and the lifting provisions of each shipping section, the conduit entry areas, the cable compartment dimensions, and the anchorage pattern
  • an assembly one-line diagram showing the incoming connection, the main and tie breakers, the bus with its continuous, short-circuit, and short-time ratings, the neutral and ground bus, and every feeder breaker by its designation
  • a breaker schedule giving the frame size, the sensor and trip rating, the trip unit type and functions, the interrupting and short-time ratings, the operation, and the accessories of every breaker, and every spare and space position
  • the bus material, plating, and sizing basis, with the bus bracing rating and the short-time withstand basis
  • the assembly short-circuit and short-time ratings and the test basis on which each is established
  • the control power source, the control voltage, and the control load of the switchgear in standby and during a trip or close of every breaker, for coordination with the source that supplies it
  • the heat release of each section at rated load, for coordination of the room ventilation
  • the seismic certification for the switchgear as furnished, where the datasheet requires one
  • product data for every breaker and trip unit, for the relays, instrument transformers, meters, and network devices, and for the surge protective device, where any is furnished within the assembly
  • schematic and wiring diagrams for the control, protection, metering, ground-fault, and communications circuits, with every terminal identified
  • the nameplate schedule listing the text to appear on each assembly and breaker nameplate
Action Submittalscheckbox
☑ Shop drawings
☑ Assembly one-line diagram
☑ Breaker schedule
☑ Bus data and bracing rating
☑ Short-circuit and short-time rating basis
☑ Control power source and control load
☑ Heat release per section
☐ Seismic certification
☑ Breaker, trip unit, relay, metering, network, and surge protective device product data
☑ Schematic and wiring diagrams
☑ Nameplate schedule
3.1.2 Switchgear shall not be released for manufacture until the action submittals covering it have been reviewed and returned.
NOTE The breaker schedule is the submittal that most often comes back wrong, because a frame size names a family of breakers whose interrupting rating, short-time rating, and trip unit functions differ within the frame, and a breaker of the right frame with the wrong sensor, the wrong trip unit, or an unfused interrupting rating below the assembly rating is not found until the schedule is read line by line against the one-line diagram. (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 time-current characteristic curves and the setting ranges of every trip unit and relay furnished, for use in the study performed under Protective Coordination StudyProtective Device Coordination StudyResolves to the current adopted revision.sync/protective-coordination-study
  • the manufacturer's published derating factors applied for ambient temperature and altitude, where either exceeds the rating basis of the listing
  • the serving utility's written acceptance of the metering compartment arrangement, where the switchgear is service equipment
  • the IEEE C37.20.7 test report for the arc-resistant configuration furnished, where arc-resistant construction is selected
Informational Submittalscheckbox
☑ Manufacturer's qualification statement
☑ Field testing firm and technician qualifications
☐ Factory test procedure
☑ Trip unit and relay characteristic data for the coordination study
☐ Ambient and altitude derating factors
☐ Utility acceptance of the metering compartment
☐ Arc-resistant construction test report

3.3 Closeout Submittals

3.3.1 The Contractor shall submit the following before any switchgear is accepted:
  • record drawings reflecting every field change to the breaker arrangement, the wiring, and the network addressing
  • the certified factory test report
  • the field acceptance test report for each lineup, 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 arc energy reduction documentation and performance test record required by NFPA 70 240.87
  • the final settings of every trip unit and relay, as commissioned, with the configuration file of every programmable device
  • the network address list and the point list for every networked device, where a network is furnished
  • the manufacturer's start-up report, where start-up services are furnished
  • operation and maintenance data covering the structure, the bus, each breaker and its racking and maintenance procedures, each trip unit and relay, and the inspection intervals the manufacturer publishes
  • the warranty certificate identifying each lineup by designation and the warranty commencement date
  • a signed receipt from the Owner for the spare parts, the handling equipment, and the keys delivered
Closeout Submittalscheckbox
☑ Record drawings
☑ Certified factory test report
☑ Field acceptance test reports
☐ Ground-fault protection performance test record
☑ Arc energy reduction documentation and test record
☑ Final trip unit and relay settings with configuration files
☐ Network address and point list
☐ Manufacturer's start-up report
☑ Operation and maintenance data
☑ Warranty certificate
☑ Spare parts, handling equipment, and keys receipt

4 Quality Assurance

4.1 Manufacturer Qualifications

4.1.1 The switchgear shall be produced by a manufacturer that has held a UL 1558 listing for switchgear of the type furnished for not less than the period indicated in the datasheet.
Manufacturer Listing Historyrange
Not less than
years
351020
4.1.2 The manufacturer shall maintain a factory-trained field service organization able to reach the site, and shall state in the qualification statement the location of the nearest service center and the period, measured from the date of manufacture, for which replacement breakers, trip units, cradles, and bus components for the switchgear platform will remain available.

4.2 Source Limitations

4.2.1 The structure, the bus, the breaker cradles, the breakers, the trip units, and the compartments built into the structure shall be furnished by the switchgear manufacturer under one UL 1558 listing.
4.2.2 Every lineup of this switchgear on the project shall be furnished by one manufacturer, so that breakers of a frame interchange between lineups and the Owner maintains one breaker family and one set of handling equipment.
NOTE A relay, a meter, a network device, or a surge protective device from another maker remains covered by the assembly listing only where the switchgear manufacturer installed it in a compartment of its own construction and evaluated it as part of the assembly; a device added to the structure in the field without that evaluation removes the switchgear from the condition under which its rating was established. (4.2.3)

4.3 Design Conformance

4.3.1 The switchgear design furnished shall have been tested for conformance in accordance with IEEE C37.51, and the breakers shall have been tested in accordance with IEEE C37.50, in the frame sizes, ratings, and compartment arrangement furnished.
4.3.2 Where the structure carries a section of UL 891 switchboard construction for group-mounted molded-case feeder breakers, that section shall be listed to UL 891, shall carry a short-circuit current rating not less than the assembly rating at its line terminals, and shall be identified on the shop drawings as a switchboard section.

4.4 Field Testing Firm

4.4.1 Field acceptance testing shall be performed by the firm indicated in the datasheet, qualified as Electrical Acceptance TestingElectrical Acceptance TestingResolves to the current adopted revision.sync/electrical-acceptance-testing requires.
Field Acceptance Testing Firmradio
○ Independent testing firm accredited to ANSI/NETA ATS
○ Manufacturer's field service organization
○ Installing contractor's own technicians
NOTE An independent firm has no stake in whether the switchgear passes and reports against a published acceptance standard; the manufacturer's organization knows the breakers and the trip units best and is already on site where start-up services are furnished; 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 built or installed the equipment would satisfy the Owner's insurer and the Authority Having Jurisdiction. (4.4.2)

5 Environmental and Service Conditions

5.1 Ambient Temperature

5.1.1 The switchgear 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 switchgear installed indoors shall be as indicated in the datasheet.
Indoor Design Ambient Temperaturerange
Not less than
°C
2530405055
NOTE IEEE C37.20.1 establishes the assembly ratings at a 40 °C ambient, and the breakers inside are rated at 40 °C under IEEE C37.13, so a 40 °C design ambient is the condition at which every rating applies without correction; a higher value covers an electrical room whose ventilation cannot hold 40 °C at design load, at the cost of a larger bus, a larger breaker frame, or forced ventilation for the same load. (5.1.3)
5.1.4 Switchgear 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 switchgear and its breakers shall be derated for AltitudeAltitudeParameterEach project supplies its own value.altitude in accordance with the correction factors of IEEE C37.20.1 and the manufacturer's published data 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 the bus and the breakers and the dielectric strength of the clearances inside the structure, so switchgear 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 Where the switchgear is installed outdoors or in a space that is not conditioned, a thermostatically controlled space heater shall be furnished in each vertical section, in the breaker compartments and the cable compartment alike.
5.3.2 Where space heaters are furnished, they shall be sized to hold the interior of each section above the dew point at Site Ambient Temperature MinimumSite Ambient Temperature MinimumParameterEach project supplies its own value.site-ambient-temperature-minimum, shall be guarded so that a conductor or a breaker cannot rest against an element, and shall be supplied from a circuit that stays energized while the switchgear main breaker is open.
NOTE Switchgear that stands in an unconditioned space cycles through the dew point with every cold night, and the condensation that forms on the bus, the primary disconnects, the trip unit electronics, and the insulating supports is the mechanism behind most tracking failures and nuisance trips on outdoor and unheated switchgear. (5.3.3)

5.4 Seismic Qualification

5.4.1 The seismic certification required for the switchgear 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 switchgear under ASCE 7 Chapter 13 (by default)
NOTE Anchorage keeps the switchgear on its pad; special certification demonstrates that the breakers stay racked, the trip units keep their settings, and the switchgear still operates after the design earthquake, which ASCE 7 requires of a component whose importance factor is above 1.0, such as switchgear 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 switchgear as furnished, including the structure, the bus, and every breaker in its compartment, in the heaviest section arrangement furnished.
5.4.4 A certificate covering a single section, an empty structure, or a breaker tested apart from the assembly shall not be accepted as certification of the switchgear.
5.4.5 A field change to the breakers installed or to the anchorage that departs from the certified configuration shall be re-evaluated by the manufacturer against the certification before the switchgear is energized.

6 Electrical Ratings

6.1 Service Configuration

6.1.1 Whether the switchgear 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 switchgear is service equipment, it shall be listed and marked as suitable for use as service equipment, and the service disconnecting means, the number and grouping of service disconnects, the available fault current marking, the main bonding jumper, and the utility's metering requirements shall comply with Electrical Service EntranceElectrical Service EntranceResolves to the current adopted revision.sync/electrical-service-entrance and Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current adopted revision.sync/grounding-and-bonding.
6.1.3 Where the switchgear is service equipment, the serving utility's metering requirements shall be confirmed in writing before the switchgear is released for manufacture, and the arrangement accepted shall be shown on the shop drawings.

6.2 Main Arrangement

6.2.1 The main arrangement of the switchgear shall be as indicated in the datasheet.
Main Arrangementselect
Single main
Double-ended, main-tie-main
Double-ended with two tie breakers and a center section
Multiple mains on a common bus
Per drawings — the one-line diagram (deferred by default)
NOTE A single main is the arrangement most lineups are built with; a double-ended lineup takes two sources onto two bus halves joined by a tie breaker, so that either source can carry the whole bus with the other out of service; two tie breakers with a center section let the tie itself be withdrawn for maintenance while the bus stays split; multiple mains on a common bus is the service arrangement in which up to the number of disconnects Electrical Service EntranceElectrical Service EntranceResolves to the current adopted revision.sync/electrical-service-entrance permits each protect a portion of the bus without a single main. (6.2.2)
6.2.3 Where a main-tie-main arrangement is furnished, the two mains and the tie shall be interlocked so that not more than two of the three breakers can be closed at one time unless the one-line diagram indicates a closed-transition scheme, and the interlock method shall be as indicated in the datasheet.
Main-Tie-Main Interlock Methodradio
○ Key interlock
○ Electrical interlock through the breaker auxiliary contacts
○ Key and electrical interlock
NOTE A key interlock enforces the two-of-three rule mechanically and works with the control power lost, but it depends on the operator carrying the key between breakers and it cannot serve an automatic transfer; an electrical interlock acts through the breaker close circuits and is what an automatic transfer scheme is built on, but it is only as good as the control power that feeds it; furnishing both covers each one's failure mode at the cost of both. (6.2.4)
6.2.5 Where a main-tie-main arrangement is furnished, the transfer scheme shall be as indicated in the datasheet.
Main-Tie-Main Transfer Schemeselect
Manual transfer only
Automatic open-transition transfer with manual return
Automatic open-transition transfer with automatic return
Automatic closed-transition transfer and return
Per drawings — the one-line diagram (deferred by default)
NOTE A manual scheme leaves the operator to open a dead main and close the tie; an automatic open-transition scheme senses the loss of one source, opens its main, and closes the tie after a time delay, with the return to normal left to the operator or made automatically after the source has been restored for a set time; a closed-transition scheme parallels the two sources for a few cycles so that the loads see no interruption on the return, and it needs a sync check and the serving utility's acceptance where the two sources are not from the same transformer. (6.2.6)
6.2.7 Where an automatic transfer scheme is furnished, the transfer controller, its voltage sensing on each source, its time delays, and its auto-manual selector shall be furnished by the switchgear manufacturer under the assembly listing, the mains and the tie shall be electrically operated, and the sequence shall be shown on the schematic diagrams and verified at field acceptance testing.

6.3 System Voltage and Frequency

6.3.1 The system voltage and configuration shall be as indicated in the datasheet.
System Voltageselect
120/240 V 1Φ 3-wire
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
480 V 3Φ 3-wire high-resistance grounded wye
600Y/347 V 3Φ 4-wire
600 V 3Φ 3-wire delta
Per drawings — the one-line diagram (deferred by default)
NOTE The number of phases and the number of wires follow from the system voltage selected, and the breaker pole count, the presence of a neutral bus, and the ground-fault sensing method follow from them in turn; a high-resistance grounded system carries no neutral load, limits a ground fault to a few amperes, and alarms rather than trips on the first ground fault, which is why its ground-fault protection is an alarm and not a trip. (6.3.2)
6.3.3 The switchgear voltage rating shall equal or exceed the system voltage, and where the switchgear is fed from a transformer secondary the Contractor shall confirm the rating against the secondary configuration of the transformer before the switchgear is released for manufacture.
6.3.4 Where the system is a high-leg delta, the high leg shall be connected to the B phase of the bus and shall be identified in accordance with NFPA 70 110.15 and 408.3(F).
6.3.5 Where the system is a 3-wire delta, a high-resistance grounded system, or another system with no grounded conductor at the switchgear, the switchgear shall be furnished without a neutral bus and the breakers shall be rated for the line-to-line voltage.
6.3.6 The system frequency shall be as indicated in the datasheet.
System Frequencyradio
● 60 Hz
○ 50 Hz

6.4 Main Bus Continuous Current

6.4.1 The main bus continuous current rating shall be as indicated in the datasheet.
Main Bus Continuous Currentrange
A
800120016002000250030003200400050006000800010000
Per drawings — the one-line diagram (deferred by default)
6.4.2 The main bus rating shall be not less than the frame rating of the main breaker where one is furnished, not less than the rating of the overcurrent device ahead of the switchgear where it has no main, and not less than the sum of the ratings of the service disconnects where multiple mains are furnished without a single main.
NOTE The bus rating is fixed by the calculated load of NFPA 70 Article 220, the transformer or service ahead of the switchgear, and the spare capacity the project wants to leave, and it is stated on the one-line diagram with the main breaker that protects it; a bus cannot be uprated after manufacture without replacing the sections that carry it, which is why the rating is chosen against the ultimate source rating rather than the first-day load, and why a rating above 6000 A is built with forced ventilation or a double bus and is quoted as a special. (6.4.3)
6.4.4 Where the main bus rating is 5000 A or more, the manufacturer shall state in the action submittals whether the rating depends on fans or on a ventilation arrangement, and where it does, the fan failure shall be alarmed and the bus rating without the fans shall be stated on the nameplate.
6.4.5 The through-bus rating basis for the distribution sections shall be as indicated in the datasheet.
Through-Bus Rating Basisradio
○ Full main bus rating through every section
○ Tapered, each section rated for the breakers it and the sections beyond it carry
NOTE A full-rated through-bus carries the main bus rating to the far end of the lineup, so that a breaker of any frame can be added in any section and a section can be added at the end without re-rating the bus; a tapered through-bus is sized in each section for the breakers actually downstream of it, which saves bus material on a long lineup and fixes the lineup to the breaker arrangement it was built for. (6.4.6)
6.4.7 Where a tapered through-bus is selected, the rating of the bus in each section shall be shown on the shop drawings, and no breaker shall be installed in a section whose through-bus rating is less than the sum of the feeder ratings it carries.

6.5 Short-Circuit and Short-Time Ratings

6.5.1 The available fault current at the line terminals of each lineup shall be as indicated on the one-line diagram.
6.5.2 The assembly short-circuit current rating marked on the nameplate of each lineup shall equal or exceed the available fault current at its line terminals as established under Short Circuit StudyShort-Circuit StudyResolves to the current adopted revision.sync/short-circuit-study, and shall be as indicated in the datasheet.
Assembly Short-Circuit Current Ratingrange
Not less than
kA
3042506585100130150200
Per drawings — the one-line diagram (deferred by default)
6.5.3 The assembly shall carry a short-time withstand rating equal to its short-circuit current rating for 30 cycles, in accordance with IEEE C37.20.1, and the bus, its supports, and every bus joint shall be braced for that current and that duration.
NOTE The 30-cycle short-time rating is the property that separates this switchgear from a switchboard: the structure carries the full fault current for a half second, so the main and tie breakers can be set with a short-time delay and no instantaneous trip, and the feeder breaker nearest the fault clears first. The duty evaluation that proves the upstream device clears within the 30 cycles is performed under Short Circuit StudyShort-Circuit StudyResolves to the current adopted revision.sync/short-circuit-study, and the settings that use the delay are established under Protective Coordination StudyProtective Device Coordination StudyResolves to the current adopted revision.sync/protective-coordination-study. (6.5.4)
NOTE The marked assembly rating is the lowest of the bus bracing, the interrupting rating of every unfused breaker, and the rating of every fused breaker with its fuses installed, so a single breaker of a lower rating racked into a compartment lowers the rating of the whole lineup. (6.5.5)

6.6 Breaker Interrupting Basis

6.6.1 Every breaker in the switchgear shall carry an interrupting rating and a short-time rating, with any integral fuses installed, not less than the assembly short-circuit current rating at the system voltage, and no series-rated combination shall be relied on anywhere in the lineup.
6.6.2 Whether the breakers are unfused or integrally fused shall be as indicated in the datasheet.
Breaker Interrupting Meansradio
○ Unfused power circuit breakers
○ Integrally fused power circuit breakers
Derived — the assembly short-circuit current rating; an unfused breaker is furnished where its interrupting rating at the system voltage meets the assembly rating, and an integrally fused breaker where it does not (by default)
NOTE An unfused power circuit breaker interrupts up to 100 kA at 480 V in the larger frames and carries the same current for 30 cycles, and it is the breaker nearly every lineup is built with; an integrally fused breaker adds current-limiting fuses in the breaker's own drawout element to reach 200 kA, with an open-fuse trip that opens the breaker when any fuse clears, at the cost of a fuse replacement after every high-magnitude fault and a frame that no longer offers the full short-time delay above the fuse's threshold current. (6.6.3)
6.6.4 Where integrally fused breakers are furnished, each shall carry an open-fuse trip and blown-fuse indication visible with the door closed, the fuses shall be the class and rating the breaker listing names, and the fuses shall be accessible only with the breaker withdrawn.

6.7 Neutral Bus

6.7.1 The neutral bus shall be as indicated in the datasheet.
Neutral Busselect
No neutral bus
Neutral bus rated 50% of the phase 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 switchgear (by default)
NOTE A three-wire system has no neutral to carry; a four-wire system whose load is largely three-phase or balanced line-to-neutral carries a neutral that NFPA 70 220.61 lets be reduced below the phase bus; a four-wire system with ordinary single-phase load carries one rated with the phase bus; and a four-wire system whose load is predominantly single-phase nonlinear equipment 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. (6.7.2)
6.7.3 Where a neutral bus is furnished, it shall be insulated from the structure, shall extend the full length of the lineup through the cable compartments, and where the switchgear 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 adopted revision.sync/grounding-and-bonding.
6.7.4 Where a neutral bus is furnished, a neutral terminal shall be furnished for every breaker position, including spare and space positions, sized for the neutral conductor of the feeder it serves, and where a trip unit senses neutral current a neutral sensor of the breaker's rating shall be mounted on the neutral bus and wired to the breaker's secondary disconnect.

6.8 Ground Bus

6.8.1 The ground bus shall be as indicated in the datasheet.
Ground Busradio
● Full-length ground bus
○ No ground bus
NOTE A lineup added to an existing lineup whose ground bus continues through the joined sections is the case in which a ground bus of its own is omitted; every free-standing lineup carries one. (6.8.2)
6.8.3 Where a ground bus is furnished, it shall be copper of not less than 1/4 in. by 2 in. cross-section, shall be bonded to each section of the structure, shall extend the full length of the lineup through the cable compartments, and shall carry a terminal for the equipment grounding conductor of every breaker position and for the bonding conductors of adjacent equipment, including a telecommunications bonding conductor where one lands at the switchgear.
6.8.4 The breaker cradle shall ground the breaker frame through a ground contact that engages before the primary disconnects make and separates after they break, in every position of travel between connected and disconnected.
6.8.5 Grounding and bonding of the switchgear shall comply with Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current adopted revision.sync/grounding-and-bonding.

7 Circuit Breakers

7.1 Breaker Construction

7.1.1 Every power circuit breaker shall be a drawout, stored-energy, two-step closing breaker built to IEEE C37.13, with a mechanism that charges the closing springs before the close command and closes the contacts in one motion independent of the operator.
7.1.2 Breakers of one frame size shall be interchangeable between every compartment of that frame in every lineup on the project, and a breaker shall not rack into a compartment of a lower rating or a different frame.
7.1.3 Each breaker shall carry on its face a contacts open and closed indicator, a springs charged and discharged indicator, a manual charging means, manual close and open pushbuttons, an operations counter, and a nameplate stating its frame size, its interrupting and short-time ratings, and its sensor rating.
7.1.4 Every breaker shall be trip-free, so that the contacts open on a trip command while the close command is held, and shall be anti-pump, so that a maintained close command produces one closing operation.
7.1.5 The feeder breaker construction of the lineup shall be as indicated in the datasheet.
Feeder Breaker Constructionradio
● Drawout power circuit breakers in every feeder position
○ Drawout power circuit breakers for the main, tie, and large feeders with group-mounted molded-case breakers in a switchboard section bolted to the lineup
NOTE A lineup of power circuit breakers throughout gives every feeder the drawout maintenance and the short-time rating the assembly is bought for, and it is the construction nearly every lineup is built as; a molded-case distribution section bolted to the lineup serves the small feeders at a fraction of the cost per position, under a UL 891 listing of its own, and those feeders clear instantaneously and are maintained with the section de-energized. (7.1.6)

7.2 Drawout Mechanism and Interlocks

7.2.1 Each breaker cradle shall provide connected, test, and disconnected positions, each held by a positive stop and identified by a position indicator visible with the compartment door closed, and the breaker shall be removable from the compartment only from the disconnected position.
7.2.2 In the test position the primary disconnects shall be separated and the secondary disconnects engaged, so that the breaker can be closed and tripped electrically from its control circuit without energizing the primary circuit.
7.2.3 The racking mechanism shall interlock so that the breaker cannot be racked between the connected and disconnected positions while closed, shall trip the breaker and discharge the closing springs if racking is attempted with the breaker closed, and shall discharge the closing springs when the breaker is withdrawn from the compartment.
7.2.4 The racking arrangement shall be as indicated in the datasheet.
Racking Arrangementradio
● Closed-door racking through a port in the compartment door
○ Open-door racking
NOTE Closed-door racking keeps the door between the operator and the breaker during the operation at which an arcing fault is most likely, which is why it is the construction most lineups are built with; open-door racking exposes the breaker face and the compartment during racking and is the construction found on older designs and on the smallest frames. (7.2.5)
7.2.6 Whether automatic shutters are furnished over the primary disconnects shall be as indicated in the datasheet.
Primary Disconnect Shuttersradio
○ Automatic shutters that close over the stationary primary disconnects as the breaker is withdrawn
○ No shutters
NOTE IEEE C37.20.1 does not require shutters on low-voltage switchgear, so they are a selection rather than a property of the listing: with shutters a withdrawn breaker leaves no energized stationary disconnect within reach of a worker in the compartment, and without them the compartment is treated as energized whenever the bus is, which is the condition under which the work practices of NFPA 70E apply to it. (7.2.7)
7.2.8 Where shutters are furnished, they shall be metal, grounded, operated by the racking motion without a separate action, and lockable in the closed position with the breaker withdrawn.
7.2.9 The compartment door shall be interlocked or constructed so that it can be closed with the breaker in any position, and each breaker shall accept a padlock that holds it open and a padlock that holds it in the disconnected or withdrawn position.
7.2.10 Secondary disconnects for the control, trip, and communications circuits shall be self-aligning, shall engage in the test and connected positions, and shall be rated for the control current of the breaker.

7.3 Breaker Operation

7.3.1 The operation of the main and tie breakers shall be as indicated in the datasheet.
Main and Tie Breaker Operationradio
● Electrically operated, with a motor-charged mechanism and electric close and trip
○ Manually operated, with a manually charged mechanism and manual close
7.3.2 The operation of the feeder breakers shall be as indicated in the datasheet.
Feeder Breaker Operationradio
○ Electrically operated, with a motor-charged mechanism and electric close and trip
○ Manually operated, with a manually charged mechanism and manual close
NOTE An electrically operated breaker is closed and opened from its control circuit, from a remote station outside the arc-flash boundary, and by a transfer scheme or a load-shed scheme, and it is what the main and tie breakers are built as on nearly every lineup; a manually operated breaker is charged and closed by hand at the breaker and costs less per position, which is the construction most feeder breakers are built with where no remote operation is wanted, while a project that operates every breaker from outside the boundary motorizes the feeders as well. (7.3.3)
7.3.4 Every breaker, whether electrically or manually operated, shall carry a shunt trip or an equivalent electrical trip means operated by its trip unit, and an electrically operated breaker shall also be closable and trippable by its manual pushbuttons with the control power lost.

7.4 Main Breaker

7.4.1 The main device of the switchgear shall be as indicated in the datasheet.
Main Deviceradio
○ Drawout power circuit breaker main
○ Incoming section without a main breaker
Per drawings — the one-line diagram (deferred by default)
7.4.2 The main breaker frame size, sensor rating, and trip rating shall be as indicated on the one-line diagram.
NOTE A main breaker gives the lineup a disconnecting means and an overcurrent device at the assembly, and its trip unit is the place the coordination study sets the main's characteristic; an incoming section without a main leaves both functions to the device upstream and saves the cost and the section of the main, which is the construction a lineup fed from a transformer secondary breaker in another assembly, or the secondary of a unit substation whose primary device protects it, is built with. (7.4.3)
7.4.4 Where the switchgear has no main breaker, 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 or 450.3 as applicable, and that device shall be accessible as the disconnecting means for the switchgear.
7.4.5 Where the switchgear is service equipment and has a single main, the main breaker shall be the service disconnecting means and shall be rated in accordance with NFPA 70 Article 230.

7.5 Feeder Breakers

7.5.1 The frame size, the pole count, the sensor rating, and the trip rating of every feeder breaker shall be as indicated on the one-line diagram.
7.5.2 Multi-pole feeder breakers shall be common-trip, so that every pole opens when any pole trips.
7.5.3 Every feeder breaker shall be rated for the system voltage, and a feeder breaker in a switchboard section shall be listed to UL 489 and installed as Low Voltage SwitchboardsLow Voltage SwitchboardsResolves to the current adopted revision.sync/low-voltage-switchboards requires for group-mounted devices.
7.5.4 The share of breaker positions in each lineup left for future feeders shall be not less than the share indicated in the datasheet, in addition to the spare and space positions the one-line diagram designates.
Spare Feeder Positionsrange
Not less than
%
1015202530
7.5.5 The form in which spare positions are furnished shall be as indicated in the datasheet.
Spare Position Provisionselect
Fully equipped compartments with cradle, primary and secondary disconnects, and shutters, without a breaker
Spare breakers installed
Unequipped space with structure and bus only
NOTE A fully equipped compartment accepts a breaker of its frame the day it is bought, without an outage, at the cost of the cradle and the disconnects; a spare breaker installed is a breaker bought now, marked spare, and left open, which lets a feeder be added without a purchase but commits the frame and the sensor rating in advance; an unequipped space holds the room in the structure and the bus run and costs least, and equipping it later means a bus outage and a field modification under the manufacturer's supervision. (7.5.6)
7.5.7 Where spare breakers are installed, the frame size and trip rating of the spares shall be as indicated on the one-line diagram, and each spare shall be left in the open position and identified as a spare.
7.5.8 Every fully equipped spare compartment shall be furnished with a door, and every unequipped space shall be closed by a bolted cover and shown on the shop drawings with the frame it is sized to receive.

7.6 Trip Units

7.6.1 Every power circuit breaker shall carry a solid-state trip unit built to IEEE C37.17, powered from its own current sensors, with adjustable settings that are displayed at the device, retained through a loss of control power, and protected against change by a cover, a seal, or a password.
7.6.2 The protective functions of the main and tie breaker trip units shall be as indicated in the datasheet.
Main and Tie Breaker Trip Unit Functionsselect
Long-time and instantaneous (LI)
Long-time, short-time, and instantaneous (LSI)
Long-time, short-time, instantaneous, and ground-fault trip (LSIG)
Long-time, short-time, and instantaneous with ground-fault alarm (LSIA)
Per drawings — the one-line diagram (deferred by default)
7.6.3 The protective functions of the feeder breaker trip units shall be as indicated in the datasheet.
Feeder Breaker Trip Unit Functionsselect
Long-time and instantaneous (LI)
Long-time, short-time, and instantaneous (LSI)
Long-time, short-time, instantaneous, and ground-fault trip (LSIG)
Long-time, short-time, and instantaneous with ground-fault alarm (LSIA)
Per drawings — the one-line diagram (deferred by default)
NOTE The short-time function is what lets a main or a tie wait for the feeder below it, and a power circuit breaker without it gives up the coordination the 30-cycle structure was bought for; the ground-fault trip is one of the ways ground-fault protection of equipment is furnished where Electrical Service EntranceElectrical Service EntranceResolves to the current adopted revision.sync/electrical-service-entrance or NFPA 70 215.10 requires it; a ground-fault alarm in place of a trip is the function a high-resistance grounded system and a continuous-process load carry, where the first ground fault is located rather than cleared. (7.6.4)
7.6.5 Where the one-line diagram indicates trip unit functions for a particular breaker that differ from the datasheet selection, the one-line diagram shall govern for that breaker.
7.6.6 The settings of every trip unit shall be as established under Protective Coordination StudyProtective Device Coordination StudyResolves to the current adopted revision.sync/protective-coordination-study, shall be applied by the manufacturer's start-up technician or the field testing firm before energization, and shall be recorded as commissioned in the closeout submittals.
7.6.7 Every trip unit shall carry a test port for secondary injection testing and shall display the cause and the magnitude of the last trip at the device.
7.6.8 The features furnished on every trip unit beyond its protective functions shall be as indicated in the datasheet.
Trip Unit Featurescheckbox
☐ Metering display of current, voltage, power, and energy at the trip unit
☐ Communications port to the switchgear network
☐ Event log of the last trips with cause, phase, and magnitude
☐ Neutral current sensing on a four-wire system
☐ Thermal memory that carries the heating of a prior overload into the next
NOTE A trip unit that meters removes the need for a separate feeder meter where the monitoring system under Electrical Power MonitoringElectrical Power Monitoring and MeteringResolves to the current adopted revision.sync/electrical-power-monitoring accepts trip unit data; the communications port is what carries that data and the maintenance switch status to the network; the event log is what tells the operator why a breaker opened at three in the morning; neutral sensing is what makes the ground-fault function read a four-wire system correctly and is wired to a sensor on the neutral bus; thermal memory keeps a repeatedly overloaded feeder from being reset into the same overload. Each adds cost per breaker, and a lineup of manually operated feeders with no network buys none of them. (7.6.9)

7.7 Ground-Fault Protection of Equipment

7.7.1 Ground-fault protection of equipment on the main and tie breakers shall be as indicated in the datasheet.
Ground-Fault Protection of Equipment on the Main and Tie Breakersselect
Not provided
Integral to the breaker trip unit
Separate ground-fault relay and sensors listed to UL 1053
Derived — NFPA 70 230.95 and 215.10 applied to the system voltage, the main breaker rating, and whether the switchgear is service equipment (by default)
NOTE Whether the main must carry ground-fault protection of equipment is fixed by code from the system grounding, the voltage to ground, and the breaker rating, so the field records the consequence of those inputs rather than a preference; a project can add ground-fault protection where code does not require it, and where it is required the means of providing it is the project selection, with the separate relay being the means used where the sensing scheme is one the trip unit cannot carry. (7.7.2)
7.7.3 Where ground-fault protection of equipment is furnished, the sensing method shall be as indicated in the datasheet.
Ground-Fault Sensing Methodselect
Residual sensing through the breaker's phase and neutral sensors
Zero-sequence sensing through one sensor around the phase and neutral conductors
Ground-return sensing on the main bonding jumper
Modified differential sensing across the mains and the tie of a multi-source four-wire system
NOTE Residual sensing sums the phase and neutral sensors already on the breaker and costs nothing beyond the neutral sensor, and its error grows with the sensor mismatch at high load; zero-sequence sensing reads the unbalance directly through one window sensor and is the more sensitive scheme, at the cost of a sensor large enough for the conductors it encircles; ground-return sensing reads the current on the main bonding jumper and sees every ground fault on the system but only at the service; modified differential sensing is the one scheme that reads correctly on a main-tie-main four-wire lineup, where the neutral current of a fault on one bus half returns through both mains and a residual or zero-sequence scheme on either main misreads it. (7.7.4)
7.7.5 Where ground-fault protection of equipment is furnished, it shall open all ungrounded conductors of the protected bus 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).
7.7.6 Where ground-fault protection of equipment is furnished on a lineup 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 adopted revision.sync/protective-coordination-study.
7.7.7 Where ground-fault protection of equipment is furnished on the main and the feeders carry ground-fault functions of their own, the main's ground-fault delay shall be set so that a feeder clears its own ground fault before the main opens, and where the switchgear serves a health care facility the two levels shall be coordinated as NFPA 70 517.17 requires.
7.7.8 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 Electrical Acceptance TestingElectrical Acceptance TestingResolves to the current adopted revision.sync/electrical-acceptance-testing, 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 phase overcurrent functions 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. (7.7.9)

7.8 Arc Energy Reduction

7.8.1 Where a breaker in the switchgear 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 breaker 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, tie, and feeder breakers shown on the one-line diagram (by default)
NOTE Whether arc energy reduction is required is fixed by the breaker rating, and on a lineup of power circuit breakers the main and most feeders cross the 1200 A threshold, so the field carries the consequence of the one-line diagram; only the method is a project selection. (7.8.2)
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 lets a breaker trip without its short-time delay unless a breaker below it reports the fault, so the delay that coordination needs is paid only when it is earned, and it needs the trip units above and below to be wired to each other; differential relaying acts without a worker's intervention and needs current transformers on every connection to the protected bus; 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 lineup is well above the load current, and it gives up the short-time delay on the breaker that carries it. (7.8.3)
7.8.4 Where energy-reducing maintenance switching is selected, the switch shall be lockable in the maintenance position, its status shall be indicated at the switch by a light visible with the door closed and, where a network is furnished, over the network, and it shall be operable from outside the arc-flash boundary where a remote station is indicated on the one-line diagram.
7.8.5 Where zone-selective interlocking is selected, the restraint wiring between the main, tie, and feeder trip units shall be furnished by the manufacturer within the lineup and brought to terminal blocks for the connection to downstream equipment, and the scheme shall be proven at field acceptance testing by injecting a feeder and a main together.
7.8.6 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.

7.9 Breaker Accessories

7.9.1 The accessories furnished on every breaker shall be as indicated in the datasheet.
Accessories on Every Breakercheckbox
☑ Bell alarm contact that distinguishes a trip on fault from a manual or remote opening
☑ Auxiliary contacts, two normally open and two normally closed, wired to terminal blocks
☐ Cradle position switch reporting the connected, test, and disconnected positions
☑ Padlocking provisions in the open position and in the withdrawn position
7.9.2 Shunt trips operated from an external contact, undervoltage releases, key interlock provisions, mechanical interlocks between paired breakers, and electric operators on breakers not already electrically operated shall be furnished on the breakers designated on the one-line diagram.
NOTE A bell alarm tells the operator the breaker opened on a fault and, where wired to lock out, keeps a remote close from reclosing onto it; the auxiliary contacts report the breaker position to the transfer scheme, the monitoring system, and the interlocks; the position switch tells the network whether a breaker reported open is racked out or merely open; an external shunt trip lets a breaker be opened from a kitchen hood suppression system, an emergency power off station, or a fire alarm interface; an undervoltage release opens the breaker when its control voltage is lost, which is the behavior wanted on a breaker that must not stay closed through a loss of control power and the behavior to avoid on one that must. (7.9.3)
7.9.4 Where a shunt trip operated from an external contact or an undervoltage release is furnished, its control voltage and the source of its signal shall be as indicated on the one-line diagram, and the circuit shall be tested through its initiating device before the switchgear is accepted.
7.9.5 Every accessory shall be the breaker manufacturer's accessory listed for the frame it is installed on, shall be installed by the switchgear manufacturer under the assembly listing, and shall be wired through the secondary disconnects to terminal blocks accessible with the breaker in any position.

8 Control Power and Control Wiring

8.1 Control Power Source

8.1.1 The control power source for the breaker charging motors, the trip and close circuits, the trip unit auxiliary functions, the relays, the transfer controller, and the network devices shall be as indicated in the datasheet.
Control Power Sourceradio
○ Control power transformer on the switchgear bus, with a capacitor trip device on each trip circuit
○ Station battery and charger furnished under the DC battery system standard
○ External AC source such as an uninterruptible power supply or an emergency panel
NOTE A control power transformer on the bus needs no external source and costs least, and because it dies with the bus it is paired with a capacitor trip device that stores enough energy to trip each breaker once after the bus is lost, which serves a lineup whose breakers are tripped by their own trip units and closed by hand or with the bus live; a station battery gives the switchgear a control source that is its own, able to close and trip every breaker with the bus dead, which is what a transfer scheme, a lockout scheme, and a lineup that is restored from a remote station need, at the cost of a battery, a charger, and a cabinet maintained under DC Battery SystemsDC Battery SystemsResolves to the current adopted revision.sync/dc-battery-systems; an external AC source gives the same independence from the bus where a UPS or an emergency panel already exists at the room, with a control source whose availability is only as good as that system's. (8.1.2)
8.1.3 Where a control power transformer is selected, it shall be mounted in the switchgear ahead of the main breaker or on the bus as the one-line diagram indicates, shall be protected by primary and secondary fuses, and shall be rated for the charging motor inrush of the largest breaker together with the standing control load.
8.1.4 Where a station battery is selected, the switchgear manufacturer shall state the standing control load and the trip and close duty of every breaker in the action submittals, the battery and its charger shall be sized and furnished under DC Battery SystemsDC Battery SystemsResolves to the current adopted revision.sync/dc-battery-systems for that load, and the DC feed shall enter the switchgear through a fused disconnect in a control compartment.
8.1.5 Where an external AC source is selected, the source shall remain available with the switchgear bus dead, and the Contractor shall confirm its capacity against the control load stated in the action submittals before the switchgear is released for manufacture.
8.1.6 Where a main-tie-main transfer scheme, a lockout scheme, or remote closing of any breaker is furnished, the control power source shall be one that remains available with the switchgear bus dead.

8.2 Control Voltage

8.2.1 The control voltage of the switchgear shall be as indicated in the datasheet.
Control Voltageselect
120 V AC
240 V AC
24 V DC
48 V DC
125 V DC
250 V DC
Derived — the control power source selected; 120 V AC from a control power transformer or an external AC source, and the nominal battery voltage established under the DC battery system standard where a station battery is selected (by default)
8.2.2 Every charging motor, close coil, trip coil, relay, and indicating device shall be rated for the control voltage, and a trip coil shall operate over the voltage range IEEE C37.13 requires for the control voltage selected.

8.3 Control Wiring

8.3.1 Control, metering, and indication wiring within the switchgear shall be stranded copper, not smaller than 14 AWG for control and 12 AWG for current transformer secondary circuits, with 600 V flame-retardant switchboard wire of Type SIS or an equivalent 90 °C thermoset insulation.
8.3.2 Every control conductor shall be identified at both ends with a permanent marker bearing the wire number shown on the wiring diagrams, and every terminal block shall be identified with the designation shown on the diagrams.
8.3.3 Control wiring shall terminate on terminal blocks rated for the control voltage, with not more than two conductors per terminal, and every circuit that leaves the switchgear shall terminate on a terminal block in a designated compartment reserved for field connections.
8.3.4 Current transformer secondary circuits shall terminate on shorting-type terminal blocks, so that a transformer can be isolated from its relay or meter without open-circuiting its secondary.
8.3.5 Control wiring shall be run in wiring troughs or bundled and supported clear of the bus and the primary connections, shall cross a compartment barrier only through a bushed opening, and shall not pass through a breaker compartment it does not serve.
8.3.6 Each control circuit shall be protected by its own fuse or circuit breaker, accessible without opening a breaker compartment, and arranged so that a fault on one breaker's control circuit does not remove control power from another.

9 Protective Relays, Metering, and Communications

9.1 Protective Relays

9.1.1 The protective relay functions furnished at the switchgear beyond those carried by the breaker trip units shall be as indicated in the datasheet.
Protective Relay Functionscheckbox
☐ Undervoltage and overvoltage (27/59)
☐ Underfrequency and overfrequency (81)
☐ Reverse power (32)
☐ Bus overcurrent (50/51)
☐ Bus differential (87B)
☐ Breaker failure (50BF)
☐ Synchronism check (25)
☐ Lockout relay (86)
Per drawings — the one-line diagram (deferred by default)
9.1.2 Where protective relays are furnished, they shall be microprocessor-based multifunction relays complying with IEEE C37.90 and tested to IEEE C37.90.1, with a display of the measured values and the settings, event recording, and a self-diagnostic alarm contact, mounted in a control compartment or on the door of a breaker compartment where they are visible with the doors closed.
9.1.3 Where protective relays are furnished, the relay, its current and voltage transformers, and its control wiring shall be furnished and installed by the switchgear manufacturer under the assembly listing, and the relay settings shall be as established under Protective Coordination StudyProtective Device Coordination StudyResolves to the current adopted revision.sync/protective-coordination-study.
NOTE A discrete relay at a low-voltage lineup is the exception rather than the rule: on most lineups the trip units carry the whole protection scheme, and a relay appears where the lineup takes a generator or a second source and needs the voltage, frequency, reverse-power, or synchronism functions a trip unit does not carry, or where the bus is large enough that differential protection earns its current transformers. (9.1.4)

9.2 Instrument Transformers

9.2.1 Current and voltage transformers furnished within the switchgear shall comply with IEEE C57.13, shall be rated for the system voltage and the assembly short-circuit current, and shall be mounted so that they can be reached with the bus de-energized without removing a breaker.
9.2.2 Current transformers serving a protective relay shall be on cores separate from those serving a meter, with a relaying accuracy class the relay manufacturer publishes as adequate for the relay burden and the assembly short-circuit current, and current transformers serving a meter shall carry the metering accuracy class Electrical Power MonitoringElectrical Power Monitoring and MeteringResolves to the current adopted revision.sync/electrical-power-monitoring requires for the metering point.
9.2.3 Voltage transformers shall be fused on the primary, mounted in a drawout or fused-disconnect arrangement that isolates them from the bus, and furnished with secondary fuses accessible with the doors closed.

9.3 Metering Provisions

9.3.1 The metering furnished within the switchgear shall be as indicated in the datasheet.
Metering Provisionsselect
No metering
Current transformer and meter mounting provisions only
Main metering
Main metering with feeder metering taken from the trip units over the network
Main and feeder metering with a meter at every breaker
NOTE Main metering records the lineup as one load, which is what a service or a tenant main needs for demand and energy; feeder data taken from the trip units makes each feeder visible for commissioning and load tracking at no cost beyond the network, at the accuracy of a protective device rather than a meter; a meter at every breaker gives revenue-grade or measurement-and-verification data per feeder at the cost of current transformers and a meter per position; mounting provisions leave the compartment and the current transformer space in place for a meter bought later. Whether a lineup carries any meter depends on what the monitoring system under Electrical Power MonitoringElectrical Power Monitoring and MeteringResolves to the current adopted revision.sync/electrical-power-monitoring wants from it, so the field asserts no default. (9.3.2)
9.3.3 Meters, their accuracy class, their current transformers, and their communications shall comply with Electrical Power MonitoringElectrical Power Monitoring and MeteringResolves to the current adopted revision.sync/electrical-power-monitoring, and where metering is furnished within the switchgear it shall be installed by the manufacturer under the UL 1558 listing in an instrument compartment separate from the cable compartment and the bus.
9.3.4 Where Adopted Energy CodeAdopted Energy CodeParameterEach project supplies its own value.adopted-energy-code requires the loads served from the switchgear 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 adopted revision.sync/electrical-power-monitoring.

9.4 Utility Metering Compartment

9.4.1 The utility metering compartment shall be as indicated in the datasheet.
Utility Metering Compartmentselect
Not furnished
Utility current transformer compartment ahead of the main, cold sequence
Utility current transformer compartment after the main, hot sequence
Derived — the service configuration and the serving utility's metering requirements as confirmed in writing (by default)
NOTE Whether a utility compartment is furnished follows from whether the switchgear is service equipment, and whether the utility's transformers sit ahead of the main or after it follows from the serving utility's metering rules, so the field records the consequence of those inputs; a cold-sequence compartment is de-energized by the service disconnect so that the utility can work in it without a utility-side disconnect, and a hot-sequence compartment is energized ahead of any customer device so that the main cannot be used to interrupt the metering. (9.4.2)
9.4.3 Where a utility metering compartment is furnished, it shall be sized, arranged, barriered, and provided with sealing provisions in accordance with the serving utility's published requirements, the utility's current transformers and meter shall be mounted on provisions the switchgear manufacturer furnishes, and the compartment shall be accessible only through its own cover or door.

9.5 Surge Protective Device Provisions

9.5.1 A surge protective device shall be furnished at the lineups indicated on the one-line diagram, and the device, its type, its ratings, its protection modes, and its lead length shall comply with Surge Protective DevicesSurge Protective DevicesResolves to the current adopted revision.sync/surge-protective-devices.
9.5.2 Where a surge protective device is furnished at a lineup, its mounting arrangement shall be as indicated in the datasheet.
Surge Protective Device Mounting Arrangementradio
○ Integral, factory-installed in a compartment of the switchgear
○ External, mounted adjacent to the switchgear and connected through a dedicated breaker
NOTE An integral device is connected to the bus by the manufacturer with the shortest lead the structure allows, is covered by the assembly listing, and is replaced from within the switchgear; an external device is connected through a feeder breaker with a lead of whatever length the installation produces, is replaced without opening the switchgear, and is the arrangement used where the switchgear is existing or where the Owner standardizes on one device family across equipment of several makers. (9.5.3)
9.5.4 Where an integral surge protective device is furnished, it shall be listed to UL 1449, shall be installed by the switchgear manufacturer under the UL 1558 listing, shall be connected to the bus through a dedicated disconnect so that it can be isolated for replacement without de-energizing the switchgear, and shall have its status indication visible with the door closed.

9.6 Communications Protocol

9.6.1 The communications protocol of the switchgear network shall be as indicated in the datasheet.
Communications Protocolselect
No network, dry contacts only
Modbus RTU
Modbus TCP
BACnet/IP
BACnet MS/TP
EtherNet/IP
DNP3
IEC 61850
NOTE The protocol has to match the system the switchgear reports to: a lineup whose meters and trip units report to the building automation system speaks the protocol that system reads, which is settled under Building Automation SystemBuilding Automation SystemResolves to the current adopted revision.sync/building-automation-system, and one reporting to a power monitoring system speaks what that system reads under Electrical Power MonitoringElectrical Power Monitoring and MeteringResolves to the current adopted revision.sync/electrical-power-monitoring; the serial protocols run on a two-wire bus and cost least, the Ethernet protocols carry the trip unit metering, the event logs, and the maintenance switch status, DNP3 is the protocol a utility or a generation control system reads, and IEC 61850 is the protocol a lineup integrated with protective relaying on a substation bus speaks. Dry contacts only is listed so that a lineup reporting through its bell alarms and auxiliary contacts alone is recorded as such rather than left blank. (9.6.2)
9.6.3 Where a network is furnished, the devices connected to it shall be as indicated in the datasheet.
Networked Devicescheckbox
☐ Meters
☐ Main and tie breaker trip units
☐ Feeder breaker trip units
☐ Protective relays
☐ Transfer controller
☐ Ground-fault relay
☐ Surge protective device status contacts
☐ Energy-reducing maintenance switch status
☐ Breaker position and cradle position contacts through an input module
9.6.4 Where a network is furnished, the network cable, the gateways, the switches, the terminations, and the power supplies for the network shall be installed by the manufacturer within the switchgear, and the network shall be brought to a terminal or a connector in a designated compartment for the field connection.
9.6.5 Network cable inside the switchgear shall be routed separately from the power conductors and the bus, and where it must cross a power conductor it shall cross at a right angle.
9.6.6 A close or trip of any breaker and a change of any setting over the network shall be disabled as delivered, and shall be enabled only where the Owner authorizes the function in writing and the system the switchgear reports to applies the authentication the Owner's operating program requires.
9.6.7 Each networked device shall be assigned an address on the network address list submitted with the action submittals, and the address shall be marked at the device.

10 Bus

10.1 Phase Bus Material

10.1.1 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 is the material nearly every power circuit breaker lineup is built with, because the breaker runbacks and the primary disconnects are copper and the joint count in a compartmentalized structure is high; 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 it is chosen where the cost difference on a long, high-rated bus matters and the environment does not attack it. (10.1.2)
10.1.3 Where copper bus is selected, it shall be copper bus bar conforming to ASTM B187 with a conductivity of not less than 98% IACS.
10.1.4 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, shall be plated over its full length, and every joint between the aluminum bus and a copper runback, terminal, or conductor shall be made with a plated joint or a connector listed for the combination.

10.2 Bus Plating

10.2.1 The bus plating shall be as indicated in the datasheet.
Bus Platingradio
○ Unplated, with plated joint contact surfaces
○ Tin-plated over the full length
○ Silver-plated over the full length
Manufacturer's standard (by default)
10.2.2 The manufacturer shall state the plating in the product data.
NOTE Bare copper bus with plating at the joints holds its contact resistance in a clean, dry interior; tin plating over the full length 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 and is the plating the breaker primary disconnects are made with. Aluminum bus is plated in every construction because its oxide forms within minutes of exposure and is an insulator. (10.2.3)
10.2.4 Plating shall be continuous over every bolted joint contact surface, every stationary primary disconnect, every breaker runback, and every splice at a shipping split.

10.3 Bus Sizing Basis

10.3.1 The basis on which the bus cross-section is sized shall be as indicated in the datasheet.
Bus Sizing Basisselect
Temperature rise per IEEE C37.20.1
Current density not exceeding 1000 A per square inch of copper
Current density not exceeding 750 A per square inch of copper
NOTE IEEE C37.20.1 sizes the bus so that its temperature rise under rated current does not exceed 65 °C over a 40 °C ambient at a plated joint, and that is the basis every listed lineup is built to and the basis the manufacturer applies unless told otherwise; a density limit of 1000 A per square inch of copper gives a bus near the listed rise in most sections and a larger bus in the compact ones; a limit of 750 A per square inch gives a cooler bus with more margin for an elevated room ambient, a future load increase, or harmonic heating, at the cost of more copper and sometimes a deeper section. (10.3.2)
10.3.3 Where a current density basis is selected for a copper bus, the equivalent density for an aluminum bus shall be the selected value multiplied by the ratio of the aluminum conductivity to the copper conductivity, and the manufacturer shall show the resulting bus cross-section on the shop drawings.

10.4 Bus Insulation

10.4.1 The bus insulation shall be as indicated in the datasheet.
Bus Insulationradio
● Bare bus in an isolated bus compartment
○ Insulated bus with flame-retardant sleeving or coating and insulating boots at the joints
NOTE Bare bus behind the compartment barriers is the construction most lineups are built with, because the bus compartment is already isolated from the breaker and cable compartments by the listing; insulated bus covers every bus surface a dropped tool or a misplaced hand could reach with a cover off and reduces the chance that an arcing fault started at one point propagates along the bus, at the cost of the insulation and of the heat it holds in, which can call for a larger bus for the same rating. (10.4.2)
10.4.3 Where insulated bus is selected, the insulation shall be flame-retardant, shall be rated for the system voltage and the bus operating temperature, shall be continuous through the barriers and the bus transitions between sections, and shall cover the joints with removable insulating boots so that a joint can be inspected and re-torqued.

10.5 Bus Joints and Bracing

10.5.1 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).
10.5.2 The bus shall be supported on insulating supports of a track-resistant, flame-retardant material that withstand the assembly short-circuit current for 30 cycles without damage, and the bus and its supports shall be rated for the system voltage.
10.5.3 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.
10.5.4 The bus shall be spliced at every shipping split by a bolted splice plate furnished by the manufacturer, and the splice shall carry the full rating of the bus it joins.
10.5.5 Bus joints and the breaker runback connections shall be accessible for inspection and re-torquing from the rear of the lineup, or from the front where the lineup is front-connected, without removing a breaker from an adjacent compartment.

10.6 Bus Extension Provisions

10.6.1 The provisions for future extension of the lineup shall be as indicated in the datasheet.
Bus Extension Provisionsselect
No extension provisions
Extension provisions at one end
Extension provisions at both ends
NOTE Extension provisions consist of a removable end closure, phase bus ends drilled for a splice, and neutral and ground bus ends drilled to match, so that a section can be added without drilling live bus; most lineups are built against a wall or an end of the room with no section to come, which is why none is the default; a lineup that is expected to grow carries the provisions at the end that will remain open, and a lineup in the middle of a room that will be fed from either side later carries them at both. (10.6.2)
10.6.3 Where extension provisions are furnished, the end at which they are furnished shall be as indicated on the electrical plans, and the through-bus to that end shall carry the rating the extension is to be made at.

11 Structure and Enclosure

11.1 Compartmentalization

11.1.1 Each breaker shall occupy a compartment of its own, separated from the adjacent breaker compartments, the bus compartment, and the cable compartment by grounded metal barriers, so that a breaker can be inserted, withdrawn, tested, and removed without exposing the operator to an energized part in another compartment.
11.1.2 The bus compartment shall be isolated from the breaker compartments and the cable compartment by grounded metal barriers, and the breaker runbacks shall pass through the barriers through insulating bushings or boots.
11.1.3 Each breaker compartment shall have a hinged door that closes over the breaker with the breaker in any position, with a window or a port through which the breaker indicators are read and the racking operation is performed, and each rear cable compartment shall be closed by a hinged door or a bolted cover with a padlockable latch.
11.1.4 The compartment barriers furnished beyond those the listing requires shall be as indicated in the datasheet.
Compartment Barriers Beyond the Listingcheckbox
☐ Barriers between the cable compartments of adjacent vertical sections
☐ Insulating covers over the bus and the runbacks within the cable compartment
☐ Barrier between the main breaker cable compartment and the feeder cable compartments
☐ Barrier isolating the utility metering compartment from the cable compartments
NOTE The listing isolates the breaker, bus, and cable compartments from one another; what it leaves open is the rear of the lineup, where the cable compartments of adjacent sections share one space and a worker landing a feeder stands beside the energized terminations of its neighbors. Barriers between the cable compartments let one feeder be worked on with the rest energized, insulating covers over the bus and the runbacks keep a dropped tool off the live parts behind the terminations, a barrier at the main keeps the incoming terminations away from the feeder work, and the metering barrier keeps the utility's compartment away from the Owner's. Each adds cost and depth, and each narrows what a worker can reach with a door open. (11.1.5)
11.1.6 Barriers shall be grounded metal or an insulating material rated for the system voltage, and a barrier required by the listing or by Electrical Service EntranceElectrical Service EntranceResolves to the current adopted revision.sync/electrical-service-entrance for the service disconnect grouping shall be furnished whatever the datasheet selects.

11.2 Enclosure Type

11.2.1 The enclosure type shall be as indicated in the datasheet.
Enclosure Type per NEMA 250select
Type 1
Type 1 gasketed
Type 2
Type 3R
Type 12
NOTE A dry, conditioned electrical room is the installed location on most projects, which is why Type 1 is the default; a gasketed Type 1 and a Type 12 keep settling dust off the primary disconnects and the trip units in an industrial room, a Type 2 sheds dripping water from piping above, and a Type 3R is the outdoor housing, built as a non-walk-in or walk-in structure around the same Type 1 sections. Every other location named in the clauses of this article calls for the type those clauses require. (11.2.2)
11.2.3 The enclosure 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 structure.
11.2.4 Switchgear installed outdoors shall have a Type 3R enclosure with rain hoods over ventilation openings, a drip shield over each door, and a sloped roof, and shall carry the space heaters this standard requires for an unconditioned location.
11.2.5 Switchgear installed indoors where airborne dust, lint, or fibers accumulate shall have an enclosure of Type 12 or Type 1 gasketed.
11.2.6 Switchgear installed indoors where dripping or light splashing of a non-corrosive liquid occurs shall have an enclosure of Type 2 or Type 12.
11.2.7 Switchgear installed where the atmosphere carries salt, chemical vapor, or another corrosive agent, including a coastal site and a wastewater facility, shall have a stainless steel enclosure as this standard provides under Enclosure Material and Finish, with a fully plated bus, and where the location is also outdoors the enclosure shall be Type 3R.
11.2.8 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 switchgear is released for manufacture.
NOTE A field opening cut in a Type 3R or Type 12 structure 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. (11.2.9)

11.3 Outdoor Housing

11.3.1 Where the switchgear is installed outdoors, the housing arrangement shall be as indicated in the datasheet.
Outdoor Housing Arrangementselect
Non-walk-in
Walk-in with a front aisle
Walk-in with a common aisle between two facing lineups
NOTE A non-walk-in housing is the smaller and lighter structure, and its working space is the outdoor pad in front of it, so that a breaker is racked and a trip unit is read in whatever the weather is doing; a walk-in housing puts the working space inside a weatherproof room so that a breaker can be withdrawn, lifted, and serviced in any weather, at the cost of a larger and heavier structure and a lifting means inside the aisle; a common aisle between two facing lineups houses a double-ended arrangement in one structure with one aisle serving both. Which of these a project builds follows from how often the breakers will be handled, the climate, and the pad available, so the field asserts no default. (11.3.2)
11.3.3 Where a walk-in housing is furnished, the aisle shall provide the working space required by NFPA 70 110.26 in front of every breaker with a breaker withdrawn on its lift device in the aisle, and the housing shall have lighting, a convenience receptacle, a door at each end of an aisle longer than 6 ft, and doors openable from inside without a key and equipped with panic hardware where NFPA 70 110.26(C) requires it.
11.3.4 Where a walk-in housing is furnished, a breaker lifting means shall be provided within the aisle, either as a lift truck that fits the aisle or as an overhead rail and hoist running the length of the aisle.

11.4 Enclosure Material and Finish

11.4.1 The enclosure material shall be as indicated in the datasheet.
Enclosure Materialselect
Painted steel
Type 304 stainless steel
Type 316 stainless steel
NOTE Painted steel is the construction the switchgear is built with and serves every enclosure type in a non-corrosive exposure; stainless steel is what a corrosive exposure is built in, with Type 316 holding up where chlorides are present, and it is quoted as a special on this product at a cost that reflects the amount of sheet in a compartmentalized structure. (11.4.2)
11.4.3 Structural members shall be steel of not less than 12 gauge, and doors and covers shall be steel of not less than 14 gauge, formed and reinforced so that a compartment door does not deflect when opened with its relays and instruments mounted on it.
11.4.4 A painted steel enclosure shall carry a baked powder coat or enamel finish over a phosphate pretreatment, applied to the interior structural members as well as the exterior, and the manufacturer shall state the finish system and its dry film thickness in the product data.
11.4.5 The finish color shall be as indicated in the datasheet.
Finish Colorselect
ANSI 61 light gray
ANSI 49 medium gray
ANSI 70 sky gray
Custom color matched to a sample furnished by the Owner
NOTE ANSI 61 is the color the equipment is finished in unless told otherwise and the one the other electrical equipment on a project most often matches; the other grays of ANSI Z55.1 and a custom color are chosen to match existing equipment in the room or an Owner's standard. (11.4.6)

11.5 Section Accessibility

11.5.1 The accessibility of the lineup shall be as indicated in the datasheet.
Section Accessibilityradio
● Rear-connected, with breaker compartments at the front and cable compartments at the rear
○ Front-connected, with the cable compartments reached from the front for installation against a wall
NOTE A rear-connected lineup lands the conductors on the breaker runbacks in a rear compartment of its own, which keeps the cable away from the breaker face, gives the large conductor bundles of a high-rated service their bending space, and is the construction nearly every lineup is built as, at the cost of a rear working space the room has to provide; a front-connected lineup brings the terminations to a front compartment beside or below the breakers so that the lineup stands against a wall, which saves the rear aisle and is the construction used where the room cannot give one, at the cost of a wider or deeper section and a smaller conductor capacity per position. (11.5.2)
11.5.3 Where a rear-connected lineup is furnished, the working space behind the switchgear shall be as NFPA 70 110.26 requires for the condition, and the rear doors or covers shall be marked to identify the breaker whose terminations lie behind each.
11.5.4 Sections shall be of uniform height and depth across the lineup, shall align flush at the front, and shall be bolted together to form a rigid continuous assembly.
11.5.5 Section height and depth shall be the manufacturer's standard for the largest frame installed, the compartment count, and the accessibility selected, and shall be shown on the shop drawings.

11.6 Incoming Connection and Cable Compartments

11.6.1 The incoming connection to the switchgear shall be as indicated in the datasheet.
Incoming Connectionselect
Cable
Busway
Bus from an adjacent assembly or a close-coupled transformer
Per drawings — the one-line diagram (deferred by default)
NOTE Cable enters the main or incoming section through the cable compartment and lands on the incoming terminals or the main breaker runbacks, which is the connection most lineups fed from a remote source are built with; busway enters through a flange the manufacturer furnishes and lands on the bus directly, which carries the high-rated service from a transformer vault without a conductor bundle; bus from an adjacent assembly or a close-coupled transformer is the connection of a unit substation or a lineup bolted to its source, in which the throat and the transition are governed by the standard that governs that arrangement. (11.6.2)
11.6.3 Where cable is the incoming connection, the incoming section shall provide the bending space NFPA 70 312.6 requires for the number and size of conductors per phase indicated on the one-line diagram, with terminals for every conductor, and where the standard section does not provide it the manufacturer shall furnish a pull section or a deeper section and shall show the space on the shop drawings.
11.6.4 Where a busway terminates at the switchgear, the busway flange, the bus connection, and the barrier at the entry shall be furnished by the switchgear manufacturer under the assembly listing, located as indicated on the electrical plans, and matched to the busway furnished under BuswayBuswayResolves to the current adopted revision.sync/busway.
11.6.5 Where bus from an adjacent assembly or a close-coupled transformer is the incoming connection, the transition section, its bus, and its barriers shall be furnished under the standard that governs the assembly, and the switchgear manufacturer shall furnish the connection flange and the bus stubs drilled to match.
11.6.6 The cable compartment at every feeder breaker shall provide the bending space NFPA 70 312.6 requires for the conductors indicated on the one-line diagram, and the manufacturer shall show the compartment dimensions and the terminal locations on the shop drawings.
11.6.7 Where a wireway or an auxiliary gutter adjoins the switchgear, the connection shall be made through the wiring space the manufacturer designates on the shop drawings with a coupling listed for the connection, and the trough shall comply with Wireways And Auxiliary GuttersWireways and Auxiliary GuttersResolves to the current adopted revision.sync/wireways-and-auxiliary-gutters.

11.7 Conduit Entry

11.7.1 Conduit entry to the switchgear shall be as indicated in the datasheet.
Conduit Entryradio
○ Top entry
○ Bottom entry
○ Top and bottom entry
Per drawings — the electrical plans (deferred by default)
11.7.2 Conduit shall enter only through the areas designated on the shop drawings, and the bus compartment, the breaker compartments, and the barriers between them shall not be penetrated by a raceway.
11.7.3 A structure in a Type 3R 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.

12 Arc-Flash Mitigation and Maintenance Safety

12.1 Arc-Resistant Construction

12.1.1 Arc-resistant construction shall be as indicated in the datasheet.
Arc-Resistant Constructionselect
Not required
Type 1 accessibility per IEEE C37.20.7
Type 2 accessibility per IEEE C37.20.7
Type 2B accessibility per IEEE C37.20.7
Type 2C accessibility per IEEE C37.20.7
NOTE Arc-resistant construction directs the products of an internal arcing fault away from a worker standing at the switchgear with the doors closed and latched, through a plenum to a discharge point where no one stands. Type 1 protects the front only, Type 2 extends the protection to the sides and the rear, Type 2B keeps it with a low-voltage control compartment door open, and Type 2C keeps it between compartments so that an arc in one does not propagate into its neighbor. It adds a plenum, reinforced doors, and pressure-relief flaps that raise the height and the cost of every section and need a discharge path the room has to provide, which is why most lineups are built without it and a project whose arc-flash study or whose operating practice puts workers at the energized switchgear buys it, with the accessibility type set by which faces of the lineup they stand at. (12.1.2)
12.1.3 Where arc-resistant construction is selected, the switchgear shall have been tested to IEEE C37.20.7 in the configuration furnished at the assembly short-circuit current rating for the duration the upstream protective device takes to clear as established under Short Circuit StudyShort-Circuit StudyResolves to the current adopted revision.sync/short-circuit-study, and the exhaust plenum and its discharge location shall be shown on the shop drawings and coordinated with Electrical RoomsElectrical RoomsResolves to the current adopted revision.sync/electrical-rooms.
12.1.4 Where arc-resistant construction is selected, the rating shall apply with every breaker compartment door closed and latched and with every breaker in the connected, test, or disconnected position, and the manufacturer shall state in the product data any position or door state in which the rating does not apply.
NOTE Arc-resistant construction does not lower the incident energy at a compartment whose door is open, and does not substitute for the arc energy reduction required by NFPA 70 240.87. (12.1.5)

12.2 Maintenance Safety Provisions

12.2.1 The maintenance safety provisions furnished shall be as indicated in the datasheet.
Maintenance Safety Provisionscheckbox
☐ Infrared inspection windows at the breaker runback connections and the bus splices
☐ Voltage presence indicator at each section
☐ Absence-of-voltage tester at the main and tie breakers
☐ Remote close and open station for the electrically operated breakers outside the arc-flash boundary
☐ Remote racking device that racks any breaker from outside the arc-flash boundary
☐ Breaker test cabinet for closing and tripping a withdrawn breaker from its own control circuit
NOTE Each provision lets a task be performed with less exposure than the alternative: an infrared window lets a connection be scanned under load with the cover on, a voltage indicator confirms the state of a section before its door is opened, an absence-of-voltage tester verifies a de-energized state without a handheld meter, a remote station lets a breaker be closed from outside the boundary, a remote racking device lets a breaker be racked with the operator outside the boundary during the operation at which an arcing fault is most likely, and a test cabinet lets a withdrawn breaker be exercised on the bench rather than in the test position of an energized lineup. (12.2.2)
12.2.3 Arc-flash warning labels shall be applied to each section, on the front and on the rear where the lineup is rear-connected, in accordance with NFPA 70 110.16 and NFPA 70E, with the values taken from the study performed under Arc Flash StudyArc-Flash StudyResolves to the current adopted revision.sync/arc-flash-study, placed so that each is read before a door is opened or a cover removed.

13 Identification

13.1 Nameplates, arc-flash warning labels, available fault current markings, and source identification shall comply with Equipment LabelingElectrical Equipment LabelsResolves to the current adopted revision.sync/equipment-labeling for material, lettering, attachment, and content, and the text shall be that listed on the nameplate schedule.
13.2 Each lineup shall carry an assembly nameplate stating the switchgear designation, the system voltage with the number of phases and wires, the main bus rating, the main breaker rating where one is furnished, the assembly short-circuit current rating and its short-time withstand rating, the control voltage, and the source that feeds it.
13.3 Each breaker compartment shall carry a nameplate on its door stating the breaker designation, the frame size and sensor rating, and the load served, matching the designation on the one-line diagram, and each breaker shall carry a nameplate on its face stating the compartment it belongs in where breakers of one frame carry different trip units or accessories.
13.4 Each rear cable compartment door or cover shall carry the designation of the breaker whose terminations lie behind it.
13.5 The manufacturer shall mark on the structure the UL 1558 listing, the arc-resistant rating and its accessibility type where furnished, and the frame and rating of breaker listed for installation in each compartment.
13.6 Where the switchgear is fed from a source that is not within sight, the location of that source and its circuit designation shall be marked on the switchgear in accordance with NFPA 70 408.4(B), and where more than one source feeds the lineup each shall be identified at the switchgear and at the tie.
13.7 Where the switchgear 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.
13.8 Whether a mimic bus is furnished shall be as indicated in the datasheet.
Mimic Busradio
● Not furnished
○ Furnished
NOTE A mimic bus is a colored line drawn on the front of the lineup that traces the bus and the breakers as the one-line diagram does, so that an operator can see which breaker feeds what without reading the nameplates; it earns its cost on a main-tie-main or a multi-source lineup whose operation depends on the operator understanding the arrangement, and most single-main lineups are built without one. (13.9)

14 Testing

14.1 Factory Tests

14.1.1 The manufacturer shall perform the production tests of UL 1558 and IEEE C37.20.1 on every lineup before shipment, including a dielectric withstand test of the bus and of the control circuits, a continuity check of every control, protection, metering, and ground-fault circuit against the schematic diagrams, a mechanical operation check of every breaker through every cradle position with every interlock and shutter, an electrical operation check of every electrically operated breaker and of the transfer sequence where one is furnished, a secondary injection check of every trip unit, an inspection of every bus joint against the listed torque, and an inspection of the assembly against the reviewed shop drawings.
14.1.2 Factory test witnessing shall be as indicated in the datasheet.
Factory Test Witnessingradio
○ Witnessed by the Owner's representative
● Certified test report without witnessing
14.1.3 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 lineup until the witness has accepted the results or has waived attendance in writing.
NOTE A witnessed test lets the Owner see every breaker rack and operate, every interlock work, and the transfer sequence run before the switchgear 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. (14.1.4)

14.2 Field Acceptance Tests

14.2.1 Field acceptance tests shall be performed on every lineup after installation is complete and before it is energized, in accordance with ANSI/NETA ATS and Electrical Acceptance TestingElectrical Acceptance TestingResolves to the current adopted revision.sync/electrical-acceptance-testing, which governs the method, the criteria, the tester, and the report, and shall include the tests indicated in the datasheet.
Field Acceptance Testscheckbox
☑ Visual and mechanical inspection including anchorage, nameplates, clearances, barriers, shutters, and doors
☑ 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, with every breaker in the connected position
☑ Contact resistance of the bus splices, the breaker runback connections, and the main and feeder terminations
☑ Racking of every breaker through every cradle position with every interlock, shutter, and position indicator verified
☑ Operation of every breaker by its manual means and, where electrically operated, from its control circuit and every remote close and trip contact
☑ Test of every trip unit at one point per function by the method selected under the acceptance testing standard
☐ Ground-fault protection of equipment performance test by primary current injection
☑ Trip unit and relay settings verification against the coordination study
☐ Protective relay tests per ANSI/NETA ATS with every element injected at its applied setting and its trip proven through to the breaker
☑ Zone-selective interlocking or other arc energy reduction performance test per NFPA 70 240.87(C)
☐ Main-tie-main interlock and transfer sequence test from a simulated loss of each source
☑ Control power loss simulation with every breaker holding its position and every trip circuit proven to trip on the capacitor trip or battery source
☐ Shunt trip, undervoltage release, and key interlock operation from the initiating device
☑ Current transformer ratio and polarity verification
☐ Meter and network function verification against the point list
☑ Neutral-to-ground separation verification on every lineup that is not service equipment
☐ Dielectric withstand of the bus, as an optional test under the acceptance testing standard
☐ Contact timing and travel of the main and tie breakers, as an optional test under the acceptance testing standard
14.2.2 Where a main-tie-main transfer scheme, ground-fault protection of equipment, protective relays, or a network is furnished, the test that proves it shall be performed whatever the datasheet selects.
14.2.3 A lineup 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.

14.3 Start-Up and Infrared Inspection

14.3.1 Manufacturer start-up services shall be as indicated in the datasheet.
Manufacturer Start-Up Servicesradio
○ Not required
○ Manufacturer's field service engineer present for energization, trip unit and relay commissioning, and the first transfer
NOTE A manufacturer's engineer at energization applies and verifies the trip unit and relay settings, the ground-fault scheme, the zone-selective interlocking, the transfer sequence, and the network with the maker's tools and configuration files, and the visit is what the manufacturer's warranty terms often require on a lineup with a transfer scheme or a network; a lineup of manually operated feeders with no relays and no network has less for that engineer to do, and the field testing firm applies its settings. (14.3.2)
14.3.3 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
14.3.4 Where infrared inspection is indicated, it shall be performed through the inspection windows where furnished or with the rear covers removed under an energized work permit, with the lineup 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 or the primary disconnect 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. (14.3.5)

15 Installation

15.1 Location and Working Space

15.1.1 The room in which the switchgear is installed shall satisfy Electrical RoomsElectrical RoomsResolves to the current adopted revision.sync/electrical-rooms where that room is an electrical room.
15.1.2 Working space in front of the switchgear, and behind it where it is rear-connected, shall comply with NFPA 70 110.26 for the system voltage and the condition of the space, shall admit the breaker lift truck in front of every compartment with its mast raised to the highest compartment, and no door swing shall reduce that space.
15.1.3 Where the lineup is rated 800 A or more and is over 6 ft wide, the working space shall have an entrance at each end in accordance with NFPA 70 110.26(C)(2), unless the arrangement satisfies one of the exceptions that section permits, and the doors of a room containing the switchgear shall open in the direction of egress and be equipped with listed panic hardware where that section requires it.
15.1.4 The dedicated electrical space above the switchgear required by NFPA 70 110.26(E) shall be kept clear of piping, ductwork, and equipment not associated with the electrical installation, and the headroom shall admit the lift truck mast and the arc-resistant plenum where one is furnished.
15.1.5 Working space shall not be used for storage at any time, and a withdrawn breaker shall not be left standing in it.
15.1.6 The switchgear shall be set on a concrete housekeeping pad constructed under Concrete PadsConcrete Equipment PadsResolves to the current adopted revision.sync/concrete-pads, extending not less than 3 in. beyond the structure on every side and not less than 4 in. above the finished floor indoors or 6 in. above finished grade outdoors, with a level surface along the full length of the lineup so that every breaker racks squarely, and with the conduit stub-ups and the anchor locations coordinated with the reviewed shop drawings before the pad is placed.
15.1.7 Where the finished floor in front of the lineup is not at the pad surface, a ramp or a raised floor shall be provided so that the lift truck reaches every compartment on a level surface.
15.1.8 The switchgear shall be anchored to the pad as indicated on the seismic anchorage details, and where seismic certification is required the anchorage shall be that on which the certification depends, with no substitute anchor used without the manufacturer's written confirmation that the certification remains valid.

15.2 Setting and Assembly

15.2.1 The Contractor shall handle, set, and assemble the switchgear in accordance with the manufacturer's instructions, lifting each shipping section by the lifting provisions furnished and never by the bus, the doors, or the breaker compartments, and shall not roll a section on pipes or bars that bear on the structure below the base channels.
15.2.2 Shipping sections shall be set plumb and level, aligned flush at the front, bolted together, and the bus spliced at every shipping split with the splice plates furnished, torqued to the manufacturer's values with a calibrated torque tool and witness-marked.
15.2.3 Breakers shipped separately shall be installed in the compartments their nameplates designate after the structure is set and the bus is spliced, racked to the disconnected position, and not racked to the connected position until the field acceptance tests of the bus are complete.
15.2.4 Every shipping brace, blocking, desiccant, and temporary ground shall be removed before the switchgear is energized, and the manufacturer's shipping checklist shall be completed and included in the field test report.
15.2.5 Where the switchgear is installed in an unconditioned space or outdoors, its space heaters shall be energized from a temporary source from the day the switchgear is set until its permanent heater circuit is in service.
15.2.6 The control power source shall be connected and verified at the control voltage, and every trip and close circuit shall be proven from the test position, before any breaker is racked to the connected position on an energized bus.

15.3 Conductor Terminations

15.3.1 The main and feeder lugs shall be of the type indicated in the datasheet.
Main and Feeder Lug Typeradio
○ Mechanical set-screw lugs
○ Compression lugs
Manufacturer's standard (by default)
15.3.2 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 switchgear 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. (15.3.3)
15.3.4 Every lug shall be listed for the conductor material and size terminated in it, shall be rated for 75 °C conductors, shall accept the number of conductors per phase indicated on the one-line diagram, and where aluminum conductors are terminated shall be listed for aluminum and the conductor prepared as the lug listing requires.
15.3.5 Every conductor termination shall be torqued to the manufacturer's published value with a calibrated torque tool, and the values applied shall be recorded in the field test report.
15.3.6 Conductors within the cable compartments shall be trained and supported so that each feeder can be identified and reached without disturbing its neighbors, shall be braced where the manufacturer's instructions require bracing for the assembly short-circuit current, shall not bear on the bus or on a runback, and shall be arranged so that the conductors of each phase are grouped as the phase sequence of the bus requires.
15.3.7 Conductor selection and installation shall comply with Conductors And CablesConductors and CablesResolves to the current adopted revision.sync/conductors-and-cables, and raceways shall comply with Raceways And ConduitRaceways and ConduitResolves to the current adopted revision.sync/raceways-and-conduit.

16 Delivery, Storage, and Handling

16.1 Each lineup shall be shipped in the largest factory-assembled sections the delivery route and the installation pathway admit, and the Contractor shall verify the door, corridor, elevator, and turning dimensions between the delivery point and the installed location against the shipping section dimensions before the switchgear is released for manufacture.
16.2 Each shipping section shall be delivered in the manufacturer's packaging with the listing marks and the nameplates intact, and shall be inspected for shipping damage at receipt.
16.3 Breakers shall be shipped in their compartments or in individual crates as the manufacturer directs, and a breaker shipped separately shall be stored upright, in its crate, with the switchgear, and installed only after the structure is set.
16.4 Switchgear 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 it shall be stored under cover on pallets, off the ground, and protected from condensation, precipitation, dust, and physical damage.
16.5 Where a lineup will stand more than 30 days in an unconditioned space before energization, its space heaters, where furnished, shall be energized from a temporary source, or the structure shall otherwise be protected from condensation.
16.6 The structure shall remain in its packaging or covered until the conductors are pulled, so that construction dust does not settle on the bus, the primary disconnects, and the trip units.
16.7 Switchgear or a breaker 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.

17 Warranty

17.1 The manufacturer shall warrant each lineup, its bus, every breaker and trip unit, and every factory-installed device against defects in materials and workmanship for the period indicated in the datasheet.
Manufacturer's Warranty Periodrange
Not less than
years
1235
17.2 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.
17.3 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 switchgear. (17.4)
17.5 The warranty coverage scope shall be as indicated in the datasheet.
Warranty Coverage Scoperadio
○ Parts only
○ Parts and labor
17.6 The Contractor shall warrant the installation, including every termination, the bus splices, the anchorage, the control wiring connections, and the field-installed accessories, for the project warranty period.
17.7 A breaker, trip unit, or bus component 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 component in the lineup.

18 Spare Parts and Handling Equipment

18.1 The Contractor shall deliver the spare parts indicated in the datasheet to the Owner before the switchgear is accepted, and shall obtain a signed receipt for them.
Spare Parts to Be Furnishedcheckbox
☐ One spare breaker of each frame size and trip unit type installed, with the accessories of the breakers it replaces
☑ One set of control fuses of each type and rating installed
☐ One set of integral breaker fuses of each class and rating installed, where fused breakers are furnished
☐ One set of indicating lamps or indicators of each type installed
☐ One close coil, one trip coil, and one charging motor of each type installed
☐ One set of door gaskets of each type, where a gasketed enclosure is furnished
☑ Two sets of keys for every lock and key interlock
☐ One pint of touch-up paint matching the finish
NOTE A spare drawout breaker is the one spare that restores a feeder in the time it takes to rack it in, and it is also the largest line item on the list, which turns on the Owner's tolerance for outage duration and on how far the nearest service center is; the coils and the charging motor are the parts that wear, and a lineup whose breakers are maintained in place rather than exchanged carries them. (18.2)
18.3 Spare breakers shall be identical to and interchangeable with the installed breakers of their frame, shall be delivered in their shipping crates, and shall be labeled with the lineup designation and the compartments they fit.
18.4 Spare parts shall be stored in a labeled cabinet in the electrical room furnished by the Contractor, and a spare breaker shall be stored in a breaker storage cabinet or in an unequipped compartment of the lineup designated for storage, never in an energized compartment.
18.5 The breaker handling equipment furnished with the switchgear shall be as indicated in the datasheet.
Breaker Handling Equipmentcheckbox
☑ Portable breaker lift truck that reaches the highest compartment of the tallest lineup
☐ Overhead lifting rail and hoist integral to the structure
☑ Racking handle and tool set for each lineup
☐ Breaker storage cabinet with positions for the spare breakers
☐ Breaker maintenance stand that holds a withdrawn breaker for inspection
NOTE A power circuit breaker above the smallest frame weighs more than a person lifts, so a lift truck or an overhead rail is what gets a breaker out of its compartment and onto the floor, and one of the two is furnished with nearly every lineup; the overhead rail is the arrangement a walk-in housing or a room too tight for a truck uses, the storage cabinet keeps a spare breaker upright and clean, and the maintenance stand lets a withdrawn breaker be inspected and exercised at bench height rather than on the floor. (18.6)
18.7 The Owner's operating personnel shall be trained on the switchgear for the period indicated in the datasheet, covering racking and breaker exchange, the lift truck, the interlocks and the key scheme, the trip unit displays and the reading of the event log, the maintenance switch, the transfer scheme where furnished, the control power source, and the manufacturer's inspection and maintenance intervals.
Operator Training Periodrange
Not less than
hours
24816

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"Low Voltage Switchgear," SynC Standards, revision 8. Licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://synergyinconstruction.com/standards/general/low-voltage-switchgear. Reference material only; not professional engineering advice and provided without warranty. Verify against governing codes and have a licensed professional review before use.