Low Voltage Switchgear
Rewritten as the UL 1558 / C37.20.1 power-circuit-breaker switchgear standard beside the UL 891 switchboard standard: independent fields for control power, racking, arc-energy reduction and metering, with settings and duty taken from the studies.
Showing changes from Rev 7
to Rev 8
in Low Voltage Switchgear.
---
title: Low Voltage Switchgear
category: Electrical / Power Distribution Equipment
−toc_depth: 3
description: >
− When to use: Metal-enclosed, low voltage power circuit breaker switchgear rated 600V and below for commercial, institutional, and industrial facilities. Covers indoor and outdoor configurations with drawout power circuit breakers. Not intended for: Panelboards (see [[sync/panelboards]]), switchboards (see [[sync/low-voltage-switchboards]]), motor control centers (see [[sync/motor-control-centers]]), or medium voltage switchgear above 600V (see [[sync/medium-voltage-switchgear]]).
+ When to use: Metal-enclosed low-voltage power circuit breaker switchgear rated 1000 V and below, listed to UL 1558 and built to IEEE C37.20.1, in which drawout low-voltage power circuit breakers built to IEEE C37.13 are individually mounted in grounded metal compartments on a common bus, whether installed as service equipment, as the secondary of a transformer, or downstream of other distribution equipment. Covers the ratings and the short-time basis, the breakers and their drawout mechanisms, operation, trip units, and accessories, ground-fault protection, arc energy reduction, control power and control wiring, the protective relays, instrument transformers, metering, surge protection, and communications provisions built into the assembly, the bus, the structure and enclosure, compartmentalization and arc-resistant construction, identification, factory and field testing, installation, warranty, spares, and breaker handling equipment, for three-phase and single-phase AC systems in indoor and outdoor locations, including walk-in and non-walk-in outdoor housings.
+
+ Not intended for: dead-front UL 891 switchboards with group-mounted or individually mounted molded-case or insulated-case devices on a common bus ([[sync/low-voltage-switchboards]]); cabinet-mounted UL 67 panelboards that subdivide a feeder into branch circuits ([[sync/panelboards]]); UL 845 lineups of starter cells on a common vertical bus ([[sync/motor-control-centers]]); anything above 1000 V ([[sync/medium-voltage-switchgear]]); the arrangement, the throat, and the coordinated ratings of a unit substation whose secondary is shipped as this switchgear ([[sync/secondary-unit-substations]], which invokes this standard for that construction); the synchronizing, load sharing, and generator protective functions of a lineup that parallels engine-generator sets ([[sync/generator-paralleling-switchgear]], which invokes this standard where the lineup is built as metal-enclosed switchgear); 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 ([[sync/electrical-service-entrance]]); the busway run itself, its hangers, and its joints ([[sync/busway]]); the trough of a wireway or auxiliary gutter adjoining the switchgear ([[sync/wireways-and-auxiliary-gutters]]); UL 508A panels for process automation ([[sync/industrial-control-panels]]); the surge protective device as a product ([[sync/surge-protective-devices]]); the meters themselves and the monitoring system they report to ([[sync/electrical-power-monitoring]]); the station battery and its charger as a product ([[sync/dc-battery-systems]]); DC switchgear; switchgear in hazardous classified locations; and the short-circuit, coordination, and arc-flash studies that establish the ratings and settings the switchgear is ordered to ([[sync/short-circuit-study]], [[sync/protective-coordination-study]], [[sync/arc-flash-study]]).
---
# Scope {toc}
−## This specification covers metal-enclosed, low voltage power circuit breaker switchgear assemblies rated 600V and below. {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. {note}
−## Switchgear covered by this standard utilizes individually mounted drawout power circuit breakers as the primary switching and protective devices. {note}
−## For applications using molded case or insulated case breakers in a non-drawout configuration, see [[sync/low-voltage-switchboards]]. {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. {note}
−## For medium voltage switchgear rated above 600V, see [[sync/medium-voltage-switchgear]]. {note}
−## Grounding and bonding per [[sync/grounding-and-bonding]]. {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. [[sync/low-voltage-switchboards]] is the UL 891 dead-front switchboard built around molded-case, insulated-case, and fusible devices; [[sync/panelboards]] is the UL 67 cabinet whose branch devices subdivide one feeder; [[sync/motor-control-centers]] is the UL 845 lineup of starter cells on a shared vertical bus; [[sync/medium-voltage-switchgear]] is anything above 1000 V. {note}
−## Equipment shall comply with UL 1558 and IEEE C37.20.1 and shall be listed and labeled by a Nationally Recognized Testing Laboratory (NRTL).
+## Where this switchgear is the secondary of a unit substation under [[sync/secondary-unit-substations]], or the construction basis of paralleling switchgear under [[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. {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. {note}
+
+## The following are governed elsewhere and are outside this standard: {note}
+
+- 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 [[sync/electrical-service-entrance]]
+- the feeders that leave the switchgear and the conductors that enter it, and their terminations, under [[sync/conductors-and-cables]]
+- the raceways entering the structure, under [[sync/raceways-and-conduit]]
+- the busway run, its supports, and its joints, under [[sync/busway]]
+- the wireway or auxiliary gutter trough that adjoins the structure, under [[sync/wireways-and-auxiliary-gutters]]
+- the grounding electrode system, the equipment grounding conductors, and the bonding of a separately derived system, under [[sync/grounding-and-bonding]]
+- the surge protective device as a product, its ratings, its protection modes, and its lead length, under [[sync/surge-protective-devices]]
+- the meters, their accuracy class, their current sensors, and the monitoring system they report to, under [[sync/electrical-power-monitoring]]
+- the station battery, its charger, and its DC distribution panel, under [[sync/dc-battery-systems]]
+- the transformer feeding the switchgear, under [[sync/medium-voltage-transformers]] or [[sync/low-voltage-dry-type-transformers]]
+- the automatic transfer switch on either side of the switchgear, under [[sync/automatic-transfer-switches]]
+- the short-circuit, coordination, and arc-flash studies, under [[sync/short-circuit-study]], [[sync/protective-coordination-study]], and [[sync/arc-flash-study]]
+- the method, the criteria, the tester, and the report of the field acceptance tests this standard names, under [[sync/electrical-acceptance-testing]]
+- the room the switchgear occupies, under [[sync/electrical-rooms]]
+- the housekeeping pad the switchgear stands on, under [[sync/concrete-pads]]
+
+## Switchgear shall be listed and labeled to UL 1558 by a Nationally Recognized Testing Laboratory and shall comply with IEEE C37.20.1.
+
+## 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.
+
+## The location and orientation of each switchgear lineup shall be as indicated on [[drawing: the electrical plans]].
+
+## 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.
+
# Referenced Standards {toc}
−## Equipment and installation shall comply with the latest edition of the following.
+## Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
+## 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 |
−| IEEE C37.20.1 | 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 C37.20.7 | Arc-Resistance Testing of Metal-Enclosed Switchgear |
−| IEEE C37.51 | Conformance Testing of Metal-Enclosed LV AC Power Circuit Breaker Switchgear |
+| 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 |
−| NFPA 70 | National Electrical Code |
−| NEMA ICS 6 | Industrial Control and Systems: Enclosures |
−| NETA ATS | Acceptance Testing Specifications for Electrical Power Equipment and Systems |
−| ASCE 7 | Minimum Design Loads and Associated Criteria for Buildings |
−| ASHRAE 90.1 | Energy Standard for Buildings (submetering requirements) |
−| ANSI/NEMA SG 3 | Low-Voltage Power Circuit Breakers |
+| 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 |
−## Where conflicts exist between referenced standards, the more stringent requirement shall govern unless otherwise directed by the Engineer of Record.
−
# Submittals {toc}
## Action Submittals {toc}
−### Contractor shall submit the following for review prior to fabrication:
+### The Contractor shall submit the following for review before any switchgear is released for manufacture:
−- Shop drawings showing front, side, and rear elevations with overall dimensions
−- Single line diagram indicating breaker frame sizes, trip ratings, and bus configuration
−- Bill of materials listing all major components
−- Breaker time-current coordination curves for all protective devices
−- Control schematic and wiring diagrams
−- Seismic certification documentation, where required
+- 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
```datasheet
−label: Submittal Documentation
+label: Action Submittals
type: checkbox
options:
− - "Shop drawings (front, side, rear elevations)"
− - "Single line diagram"
− - "Bill of materials"
− - "Time-current coordination curves"
− - "Control schematics and wiring diagrams"
− - "Seismic certification (IBC/ASCE 7)"
− - "Arc flash calculation input data"
− - "Catalog cut sheets for all protective devices"
+ - "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"
default:
− - "Shop drawings (front, side, rear elevations)"
− - "Single line diagram"
− - "Bill of materials"
− - "Time-current coordination curves"
− - "Control schematics and wiring diagrams"
+ - "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"
+ - "Breaker, trip unit, relay, metering, network, and surge protective device product data"
+ - "Schematic and wiring diagrams"
+ - "Nameplate schedule"
+constraint: all_of
```
+### Switchgear shall not be released for manufacture until the action submittals covering it have been reviewed and returned.
+
+### 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. {note}
+
+## Informational Submittals {toc}
+
+### 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 [[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
+
+```datasheet
+label: Informational Submittals
+type: checkbox
+options:
+ - "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"
+default:
+ - "Manufacturer's qualification statement"
+ - "Field testing firm and technician qualifications"
+ - "Trip unit and relay characteristic data for the coordination study"
+constraint: all_of
+```
+
## Closeout Submittals {toc}
−### Contractor shall provide at substantial completion:
+### The Contractor shall submit the following before any switchgear is accepted:
−- Operation and maintenance manuals, bound with table of contents
−- As-built shop drawings reflecting field modifications
−- Factory and field test reports
−- Warranty documentation
−- Spare parts inventory with reorder information
+- 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
```datasheet
label: Closeout Submittals
type: checkbox
options:
− - "Operation and maintenance manuals, bound with table of contents"
− - "As-built shop drawings reflecting field modifications"
− - "Factory and field test reports"
− - "Warranty documentation"
− - "Spare parts inventory with reorder information"
+ - "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"
default:
− - "Operation and maintenance manuals, bound with table of contents"
− - "As-built shop drawings reflecting field modifications"
− - "Factory and field test reports"
− - "Warranty documentation"
− - "Spare parts inventory with reorder information"
+ - "Record drawings"
+ - "Certified factory test report"
+ - "Field acceptance test reports"
+ - "Arc energy reduction documentation and test record"
+ - "Final trip unit and relay settings with configuration files"
+ - "Operation and maintenance data"
+ - "Warranty certificate"
+ - "Spare parts, handling equipment, and keys receipt"
+constraint: all_of
```
…2 unchanged lines
## Manufacturer Qualifications {toc}
−### Switchgear shall be manufactured by a single company responsible for the assembly, bus, and all integral protective devices.
+### 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.
−### The manufacturer shall have a minimum of five years documented experience producing UL 1558 listed switchgear.
+```datasheet
+label: Manufacturer Listing History
+type: range
+unit: years
+options:
+ min: 0
+ max: 20
+ setpoints: [0, 3, 5, 10, 20]
+default: 5
+constraint: min
+```
−### The manufacturer shall maintain an ISO 9001 certified quality management system.
+### 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.
−### The manufacturer shall maintain a 24/7 service organization with factory-trained field representatives available within 24 hours of notification.
−
## Source Limitations {toc}
−### All switchgear sections, bus, circuit breakers, protective relays, and metering equipment shall be produced or furnished by the switchgear manufacturer as an integrated assembly.
+### 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.
−### Third-party components assembled by others are not acceptable.
+### 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.
−## Testing Personnel Qualifications {toc}
+### 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. {note}
−### Acceptance testing shall be performed by a firm regularly engaged in testing electrical power equipment, employing technicians certified by NETA or equivalent.
+## Design Conformance {toc}
−### Testing personnel shall have a minimum of three years experience testing low voltage switchgear assemblies.
+### 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.
+### 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.
+
+## Field Testing Firm {toc}
+
+### Field acceptance testing shall be performed by the firm indicated in the datasheet, qualified as [[sync/electrical-acceptance-testing]] requires.
+
+```datasheet
+label: Field Acceptance Testing Firm
+type: radio
+options:
+ - "Independent testing firm accredited to ANSI/NETA ATS"
+ - "Manufacturer's field service organization"
+ - "Installing contractor's own technicians"
+```
+
+### 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. {note}
+
# Environmental and Service Conditions {toc}
−## Switchgear shall be suitable for continuous operation under the ambient conditions indicated in the datasheet.
+## Ambient Temperature {toc}
−## The design maximum ambient temperature at the installation shall be as indicated in the datasheet.
+### The switchgear shall carry its nameplate ratings continuously at the design ambient temperature of the space it is installed in.
+### The design ambient temperature for switchgear installed indoors shall be as indicated in the datasheet.
+
```datasheet
−label: Ambient Temperature (Maximum)
+label: Indoor Design Ambient Temperature
type: range
unit: °C
options:
− min: 40
+ min: 25
max: 55
− setpoints: [40, 50, 55]
+ setpoints: [25, 30, 40, 50, 55]
default: 40
+constraint: min
```
−## 40 °C is the standard ambient rating point for low voltage switchgear assemblies; 50 °C is the conventional tropical rating and 55 °C the desert or rooftop rating, and an elevated ambient is a manufacturer-configured option that derates the assembly rather than a catalog standard. {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. {note}
−## The installation altitude shall be as indicated in the datasheet.
+### Switchgear installed outdoors or in a space that follows the outdoor temperature shall be rated for [[parameter: site-ambient-temperature-maximum]] where that temperature exceeds 40 °C, and the manufacturer shall state the derating applied in the action submittals.
−```datasheet
−label: Installation Altitude
−type: select
−options:
− - "Below 6,600 ft (2,000 m) - no derating"
− - "6,600 - 9,900 ft (2,000 - 3,000 m) - derating required"
− - "Above 9,900 ft (3,000 m) - consult manufacturer"
−default: "Below 6,600 ft (2,000 m) - no derating"
−```
+## Altitude {toc}
−## The corrosion severity classification of the installation environment shall be as indicated in the datasheet.
+### The switchgear and its breakers shall be derated for [[parameter: 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.
+### 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. {note}
+
+### Ambient temperature derating and altitude derating shall be applied cumulatively where both conditions apply.
+
+## Condensation Control {toc}
+
+### 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.
+
+### Where space heaters are furnished, they shall be sized to hold the interior of each section above the dew point at [[parameter: 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.
+
+### 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. {note}
+
+## Seismic Qualification {toc}
+
+### The seismic certification required for the switchgear shall be as indicated in the datasheet.
+
```datasheet
−label: Corrosion Severity
+label: Seismic Certification Requirement
type: select
+derived: "[[parameter: seismic-design-category]] and the component importance factor assigned to the switchgear under ASCE 7 Chapter 13"
options:
− - "C2 - Low (indoor, climate-controlled)"
− - "C3 - Medium (indoor, unconditioned)"
− - "C4 - High (coastal, chemical exposure)"
− - "C5 - Very High (industrial, marine)"
+ - "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"
+default: derived
```
−## The corrosion classification is an assessment of the actual installation environment made by the Engineer; there is no classification that is correct for every project, so the field carries no 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. {note}
−## See [[sync/electrical-rooms]] for room environmental classification requirements. {note}
+### Where seismic certification is required, it shall be performed in accordance with the seismic provisions of [[parameter: 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.
−## Where site conditions exceed the parameters indicated in the datasheet, the Contractor shall notify the manufacturer and derate equipment accordingly.
+### 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.
−## Equipment rated for standard conditions (40°C, below 6,600 ft) shall be derated per IEEE C37.20.1 when installed outside these parameters.
+### 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.
−## The Engineer shall document derating calculations on the contract drawings.
+# Electrical Ratings {toc}
−## For installations classified C4 or C5, bus bars shall be copper (tin or silver-plated).
+## Service Configuration {toc}
−## For installations classified C4 or C5, enclosure paint systems shall provide enhanced corrosion protection per IEEE C57.12.29.
+### Whether the switchgear is service equipment shall be as indicated in the datasheet.
−## Seismic Requirements {toc}
−
−### The seismic certification basis shall be as indicated in the datasheet.
−
```datasheet
−label: Seismic Certification
−type: select
−drawing_ref: "structural drawings"
+label: Service Configuration
+type: radio
+drawing_ref: "the one-line diagram"
options:
− - "Not required"
− - "IBC/ASCE 7 - Importance Factor 1.0"
− - "IBC/ASCE 7 - Importance Factor 1.5 (essential facility)"
− - "OSHPD pre-approval required (California healthcare)"
+ - "Service equipment"
+ - "Downstream distribution equipment"
default: deferred
```
−### The Seismic Design Category and Importance Factor are established by the project's structural design; the electrical scope adopts them rather than setting them. {note}
+### 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 [[sync/electrical-service-entrance]] and [[sync/grounding-and-bonding]].
−### Where required by the applicable building code, switchgear shall be seismically certified by shake-table testing per ICC ES AC156 or by analysis per ASCE 7.
+### 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.
−### Seismic certification shall be by an independent third-party testing laboratory.
+## Main Arrangement {toc}
−### Certification shall cover the complete assembly including all circuit breakers, bus, and ancillary components as installed.
+### The main arrangement of the switchgear shall be as indicated in the datasheet.
−### Certification of individual components in isolation is not acceptable.
+```datasheet
+label: Main Arrangement
+type: select
+drawing_ref: "the one-line diagram"
+options:
+ - "Single main"
+ - "Double-ended, main-tie-main"
+ - "Double-ended with two tie breakers and a center section"
+ - "Multiple mains on a common bus"
+default: deferred
+```
−# Electrical Requirements {toc}
+### 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 [[sync/electrical-service-entrance]] permits each protect a portion of the bus without a single main. {note}
−## System Ratings {toc}
+### 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.
−### Whether the switchgear serves as main service entrance equipment shall be as indicated in the datasheet.
−
```datasheet
−label: Service Entrance Equipment
+label: Main-Tie-Main Interlock Method
type: radio
−drawing_ref: "one-line diagram"
options:
− - "Main service entrance equipment"
− - "Downstream distribution equipment"
+ - "Key interlock"
+ - "Electrical interlock through the breaker auxiliary contacts"
+ - "Key and electrical interlock"
+```
+
+### 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. {note}
+
+### Where a main-tie-main arrangement is furnished, the transfer scheme shall be as indicated in the datasheet.
+
+```datasheet
+label: Main-Tie-Main Transfer Scheme
+type: select
+drawing_ref: "the one-line diagram"
+options:
+ - "Manual transfer only"
+ - "Automatic open-transition transfer with manual return"
+ - "Automatic open-transition transfer with automatic return"
+ - "Automatic closed-transition transfer and return"
default: deferred
```
−### The nominal system voltage and configuration shall be as indicated in the datasheet.
+### 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. {note}
+### 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.
+
+## System Voltage and Frequency {toc}
+
+### The system voltage and configuration shall be as indicated in the datasheet.
+
```datasheet
label: System Voltage
type: select
−drawing_ref: "one-line diagram"
+drawing_ref: "the one-line diagram"
options:
− - "120/208V 3Φ 4-wire"
− - "277/480V 3Φ 4-wire"
− - "480V 3Φ 3-wire"
− - "240V 3Φ 3-wire"
+ - "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"
default: deferred
```
+### 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. {note}
+
+### 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.
+
+### 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).
+
+### 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.
+
### The system frequency shall be as indicated in the datasheet.
```datasheet
label: System Frequency
type: radio
−unit: Hz
options:
- "60 Hz"
…2 unchanged lines
```
−### 60 Hz is the North American norm and is the datasheet default; 50 Hz equipment is a distinct product selection, available for systems that operate at that frequency. {note}
+## Main Bus Continuous Current {toc}
−### Where switchgear serves as main service entrance equipment, it shall comply with NFPA 70 Article 230 including provisions for metering, service disconnect, and available fault current labeling.
+### The main bus continuous current rating shall be as indicated in the datasheet.
−### The Contractor shall coordinate metering requirements with the serving utility prior to submittal.
−
−## Bus Rating {toc}
−
−### Main bus continuous current rating shall be as indicated in the datasheet.
−
```datasheet
label: Main Bus Continuous Current
type: range
unit: A
−drawing_ref: "one-line diagram"
+drawing_ref: "the one-line diagram"
options:
min: 800
− max: 6000
− setpoints: [800, 1200, 1600, 2000, 2500, 3000, 4000, 5000, 6000]
+ max: 10000
+ setpoints: [800, 1200, 1600, 2000, 2500, 3000, 3200, 4000, 5000, 6000, 8000, 10000]
default: deferred
+constraint: exact
```
−### Short-circuit current rating shall equal or exceed the available fault current at the switchgear terminals.
+### 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.
+### 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. {note}
+
+### 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.
+
+### The through-bus rating basis for the distribution sections shall be as indicated in the datasheet.
+
```datasheet
−label: Short-Circuit Current Rating
+label: Through-Bus Rating Basis
+type: radio
+options:
+ - "Full main bus rating through every section"
+ - "Tapered, each section rated for the breakers it and the sections beyond it carry"
+```
+
+### 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. {note}
+
+### 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.
+
+## Short-Circuit and Short-Time Ratings {toc}
+
+### The available fault current at the line terminals of each lineup shall be as indicated on [[drawing: the one-line diagram]].
+
+### 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 [[sync/short-circuit-study]], and shall be as indicated in the datasheet.
+
+```datasheet
+label: Assembly Short-Circuit Current Rating
type: range
−unit: kAIC
−drawing_ref: "one-line diagram"
+unit: kA
+drawing_ref: "the one-line diagram"
options:
− min: 42
+ min: 30
max: 200
− setpoints: [42, 65, 85, 100, 200]
+ setpoints: [30, 42, 50, 65, 85, 100, 130, 150, 200]
default: deferred
+constraint: min
```
−### Bus short-time withstand rating shall be coordinated with the downstream protective device settings required to maintain selective coordination.
+### 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.
+### 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 [[sync/short-circuit-study]], and the settings that use the delay are established under [[sync/protective-coordination-study]]. {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. {note}
+
+## Breaker Interrupting Basis {toc}
+
+### 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.
+
+### Whether the breakers are unfused or integrally fused shall be as indicated in the datasheet.
+
```datasheet
−label: Short-Time Withstand Rating
−type: select
+label: Breaker Interrupting Means
+type: radio
+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"
options:
− - "30-cycle (0.5 seconds)"
− - "15-cycle (0.25 seconds)"
−default: "30-cycle (0.5 seconds)"
+ - "Unfused power circuit breakers"
+ - "Integrally fused power circuit breakers"
+default: derived
```
−### Bus shall be braced for the available short-circuit current at the point of installation as determined by a short-circuit analysis per IEEE 551.
+### 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. {note}
−### The Contractor shall verify available fault current with the utility provider and perform a short-circuit study per [[sync/short-circuit-study]] prior to equipment procurement.
+### 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.
−## Neutral and Ground Bus {toc}
+## Neutral Bus {toc}
−### The neutral bus rating shall be as indicated in the datasheet.
+### The neutral bus shall be as indicated in the datasheet.
```datasheet
−label: Neutral Bus Rating
+label: Neutral Bus
type: select
+derived: "the system voltage configuration and the share of nonlinear load served from the switchgear"
options:
− - "Full rated (100% of main bus)"
− - "Reduced (50% of main bus)"
− - "Oversized (200% of main bus)"
− - "Not applicable (3-wire system)"
−default: "Full rated (100% of main bus)"
+ - "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"
+default: derived
```
−### Whether a ground bus is furnished with the assembly shall be as indicated in the datasheet.
+### 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. {note}
+### 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 [[sync/grounding-and-bonding]].
+
+### 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.
+
+## Ground Bus {toc}
+
+### The ground bus shall be as indicated in the datasheet.
+
```datasheet
label: Ground Bus
type: radio
options:
− - "Included — full length of the assembly"
− - "Not required"
−default: "Included — full length of the assembly"
+ - "Full-length ground bus"
+ - "No ground bus"
+default: "Full-length ground bus"
```
−### A full-length ground bus is the normal construction and is the datasheet default; "Not required" exists for the rare retrofit line-up that is bonded to an existing ground bus carried through the switchgear structure. {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. {note}
−### Oversized neutral bus is required where nonlinear loads exceed 30% of the total connected load to accommodate triplen harmonic currents.
+### 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.
−### The Engineer shall evaluate harmonic loading per IEEE 519 when selecting neutral bus sizing.
+### 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.
−### Where a ground bus is furnished, it shall be bare copper, minimum 1/4 in. x 2 in. cross-section, extending the full length of the switchgear assembly.
+### Grounding and bonding of the switchgear shall comply with [[sync/grounding-and-bonding]].
−### Ground bus shall be accessible without removing any covers or barriers required for safe operation.
+# Circuit Breakers {toc}
−# Physical Construction {toc}
+## Breaker Construction {toc}
−## Enclosure {toc}
+### 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.
−### The enclosure rating shall be as indicated in the datasheet.
+### 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.
+### 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.
+
+### 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.
+
+### The feeder breaker construction of the lineup shall be as indicated in the datasheet.
+
```datasheet
−label: Enclosure Rating
−type: select
+label: Feeder Breaker Construction
+type: radio
options:
− - "NEMA 1 - indoor general purpose"
− - "NEMA 3R - outdoor rainproof"
− - "NEMA 12 - industrial (dust-tight)"
− - "NEMA 4X - outdoor, watertight and corrosion-resistant"
−default: "NEMA 1 - indoor general purpose"
+ - "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"
+default: "Drawout power circuit breakers in every feeder position"
```
−### Enclosures for outdoor installation shall be rated NEMA 3R minimum.
+### 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. {note}
−### The accessibility configuration shall be as indicated in the datasheet.
+## Drawout Mechanism and Interlocks {toc}
+### 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.
+
+### 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.
+
+### 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.
+
+### The racking arrangement shall be as indicated in the datasheet.
+
```datasheet
−label: Front Accessibility
+label: Racking Arrangement
type: radio
options:
− - "Front accessible (cable and bus access from the front)"
− - "Front and rear accessible"
−default: "Front accessible (cable and bus access from the front)"
+ - "Closed-door racking through a port in the compartment door"
+ - "Open-door racking"
+default: "Closed-door racking through a port in the compartment door"
```
−### Switchgear overall dimensions and arrangement shall be [[drawing: as indicated on the contract documents]].
+### 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. {note}
−### Enclosure shall be fabricated from galvanized steel with a minimum thickness of 12 gauge (2.66 mm) for structural members and 14 gauge (1.90 mm) for covers and doors.
+### Whether automatic shutters are furnished over the primary disconnects shall be as indicated in the datasheet.
−### All joints shall be continuously welded or bolted with gaskets as required for the specified NEMA rating.
+```datasheet
+label: Primary Disconnect Shutters
+type: radio
+options:
+ - "Automatic shutters that close over the stationary primary disconnects as the breaker is withdrawn"
+ - "No shutters"
+```
−### For outdoor installations (NEMA 3R), enclosure shall include sun shields, rain hoods over ventilation openings, and condensation heaters in each section.
+### 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. {note}
−### For outdoor installations (NEMA 3R), heater sizing shall be a minimum of 250W per vertical section.
+### 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.
−### For outdoor installations (NEMA 3R), heaters shall be thermostat controlled and wired to remain energized whenever the switchgear is de-energized.
+### 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.
−### Rear-accessible configurations require minimum 36 in. working clearance at rear per NFPA 70 Article 110.26.
+### 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.
−### Rear compartments shall have individual hinged doors with padlockable latches.
+## Breaker Operation {toc}
−## Bus Bars {toc}
+### The operation of the main and tie breakers shall be as indicated in the datasheet.
−### The bus bar material and plating shall be as indicated in the datasheet.
−
```datasheet
−label: Bus Bar Material
+label: Main and Tie Breaker Operation
type: radio
options:
− - "Copper, unplated except at joint contact surfaces"
− - "Copper, tin-plated"
− - "Copper, silver-plated"
−default: "Copper, unplated except at joint contact surfaces"
+ - "Electrically operated, with a motor-charged mechanism and electric close and trip"
+ - "Manually operated, with a manually charged mechanism and manual close"
+default: "Electrically operated, with a motor-charged mechanism and electric close and trip"
```
−### Provisions for future bus extension shall be as indicated in the datasheet.
+### The operation of the feeder breakers shall be as indicated in the datasheet.
```datasheet
−label: Bus Extension Provisions
+label: Feeder Breaker Operation
type: radio
options:
− - "No future extension"
− - "Provision for future extension at one end"
− - "Provision for future extension at both ends"
−default: "No future extension"
+ - "Electrically operated, with a motor-charged mechanism and electric close and trip"
+ - "Manually operated, with a manually charged mechanism and manual close"
```
−### Bus bar joints shall be bolted with Belleville washers to maintain contact pressure under thermal cycling.
+### 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. {note}
−### All joint contact surfaces shall be silver-plated.
+### 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.
−### Bus connections shall be designed to be accessible for re-torquing during maintenance without de-energizing adjacent sections.
+## Main Breaker {toc}
−### Phase bus shall be fully insulated with flame-retardant material rated for the operating temperature of the bus.
+### The main device of the switchgear shall be as indicated in the datasheet.
−### Bus insulation shall be continuous through barriers and bus transitions between sections.
+```datasheet
+label: Main Device
+type: radio
+drawing_ref: "the one-line diagram"
+options:
+ - "Drawout power circuit breaker main"
+ - "Incoming section without a main breaker"
+default: deferred
+```
−## Barriers and Compartmentalization {toc}
+### The main breaker frame size, sensor rating, and trip rating shall be as indicated on [[drawing: the one-line diagram]].
−### Switchgear shall provide metal barriers between all functional units and between the bus compartment and cable compartment.
+### 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. {note}
−### Barriers shall prevent propagation of an arc fault from one compartment to adjacent compartments.
+### 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.
−### Individual circuit breaker compartments shall allow insertion, withdrawal, and testing of any breaker without exposing personnel to energized components in adjacent compartments.
+### 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.
−### Interlocks shall prevent opening compartment doors while the breaker is in the connected position.
+## Feeder Breakers {toc}
−## Arc Resistance {toc}
+### The frame size, the pole count, the sensor rating, and the trip rating of every feeder breaker shall be as indicated on [[drawing: the one-line diagram]].
−### The arc-resistant construction type shall be as indicated in the datasheet.
+### Multi-pole feeder breakers shall be common-trip, so that every pole opens when any pole trips.
+### 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 [[sync/low-voltage-switchboards]] requires for group-mounted devices.
+
+### 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.
+
```datasheet
−label: Arc-Resistant Construction
+label: Spare Feeder Positions
+type: range
+unit: '%'
+options:
+ min: 0
+ max: 30
+ setpoints: [0, 10, 15, 20, 25, 30]
+constraint: min
+```
+
+### The form in which spare positions are furnished shall be as indicated in the datasheet.
+
+```datasheet
+label: Spare Position Provision
type: select
options:
− - "Not required"
− - "Type 1 - front"
− - "Type 2 - front and rear"
− - "Type 2B - front, rear, and sides"
− - "Type 2C - front, rear, sides, and between units"
+ - "Fully equipped compartments with cradle, primary and secondary disconnects, and shutters, without a breaker"
+ - "Spare breakers installed"
+ - "Unequipped space with structure and bus only"
```
−### Arc-resistant construction is an added-cost option rather than a baseline requirement, and the accessibility type turns on which sides of the equipment personnel occupy, so no type is correct for every project and the field carries no default. {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. {note}
−### See [[sync/arc-flash-study]] for arc flash study requirements and labeling. {note}
+### Where spare breakers are installed, the frame size and trip rating of the spares shall be as indicated on [[drawing: the one-line diagram]], and each spare shall be left in the open position and identified as a spare.
−### Where arc-resistant construction is specified, switchgear shall be tested per IEEE C37.20.7 at the specified short-circuit current rating and duration.
+### 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.
−### Arc-resistant design shall redirect arc gases through plenums or ducts to areas where personnel are not present.
+## Trip Units {toc}
−### Pressure relief flaps and reinforced enclosure construction shall contain the arc event.
+### 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.
−### Arc-resistant construction does not eliminate the need for arc flash hazard analysis per IEEE 1584. {note}
+### The protective functions of the main and tie breaker trip units shall be as indicated in the datasheet.
−## Infrared Scanning Provisions {toc}
+```datasheet
+label: Main and Tie Breaker Trip Unit Functions
+type: select
+drawing_ref: "the one-line diagram"
+options:
+ - "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)"
+default: deferred
+```
−### Enclosure shall include removable infrared inspection windows or cover plates at each bus joint, main breaker connections, and feeder breaker connections.
+### The protective functions of the feeder breaker trip units shall be as indicated in the datasheet.
−### Windows shall allow thermographic inspection of energized connections without removing covers or de-energizing equipment.
+```datasheet
+label: Feeder Breaker Trip Unit Functions
+type: select
+drawing_ref: "the one-line diagram"
+options:
+ - "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)"
+default: deferred
+```
−# Circuit Breakers {toc}
+### 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 [[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. {note}
−## Main Circuit Breaker {toc}
+### 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.
−### The main breaker configuration shall be as indicated in the datasheet.
+### The settings of every trip unit shall be as established under [[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.
+### 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.
+
+### The features furnished on every trip unit beyond its protective functions shall be as indicated in the datasheet.
+
```datasheet
−label: Main Breaker Configuration
−type: select
−drawing_ref: "one-line diagram"
+label: Trip Unit Features
+type: checkbox
options:
− - "Power circuit breaker (drawout)"
− - "Main lugs only (no main breaker)"
−default: deferred
+ - "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"
+constraint: all_of
```
−### The main breaker trip unit shall be as indicated in the datasheet.
+### A trip unit that meters removes the need for a separate feeder meter where the monitoring system under [[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. {note}
+## Ground-Fault Protection of Equipment {toc}
+
+### Ground-fault protection of equipment on the main and tie breakers shall be as indicated in the datasheet.
+
```datasheet
−label: Main Breaker Trip Unit
+label: Ground-Fault Protection of Equipment on the Main and Tie Breakers
type: select
+derived: "NFPA 70 230.95 and 215.10 applied to the system voltage, the main breaker rating, and whether the switchgear is service equipment"
options:
− - "Electronic trip - LSI (Long-time, Short-time, Instantaneous)"
− - "Electronic trip - LSIG (Long-time, Short-time, Instantaneous, Ground Fault)"
−default: "Electronic trip - LSIG (Long-time, Short-time, Instantaneous, Ground Fault)"
+ - "Not provided"
+ - "Integral to the breaker trip unit"
+ - "Separate ground-fault relay and sensors listed to UL 1053"
+default: derived
```
−### Main breaker frame size and trip rating shall be [[drawing: as indicated on the one-line diagram]].
+### 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. {note}
−### Circuit breakers shall comply with IEEE C37.13 and shall be drawout, stored-energy type with manual charging and electrical close/trip capability.
+### Where ground-fault protection of equipment is furnished, the sensing method shall be as indicated in the datasheet.
−### Each breaker shall have three distinct positions: connected, test, and disconnected.
+```datasheet
+label: Ground-Fault Sensing Method
+type: select
+options:
+ - "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"
+```
−### It shall not be possible to move a breaker between positions with the door closed unless motor operators are provided.
+### 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. {note}
−### LSIG trip units are recommended for all applications. {note}
+### 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).
−### Ground fault protection is required by NFPA 70 Article 230.95 for solidly grounded wye services of more than 150V to ground and 1000A or more.
+### 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 [[sync/protective-coordination-study]].
−### Even where not code-required, ground fault protection significantly reduces equipment damage from arcing faults. {note}
+### 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.
−## Arc Flash Mitigation {toc}
+### 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 [[sync/electrical-acceptance-testing]], and the written record shall be delivered with the closeout submittals.
−### NFPA 70 Article 240.87 requires that circuit breakers rated 1200A or more have one of several arc energy reduction methods; each trades maintenance-mode operating burden against cost and against how much incident energy is actually removed. {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. {note}
−### The arc energy reduction method for circuit breakers rated 1200A or more shall be as indicated in the datasheet.
+## Arc Energy Reduction {toc}
+### 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.
+
```datasheet
−label: Arc Energy Reduction Method (1200A+ Breakers)
+label: Arc Energy Reduction Method
type: select
+derived: "NFPA 70 240.87 applied to the rating of the main, tie, and feeder breakers shown on the one-line diagram"
options:
− - "Zone-selective interlocking (ZSI)"
+ - "Not applicable, no breaker rated 1200 A or more"
+ - "Energy-reducing maintenance switching with local status indicator"
+ - "Zone-selective interlocking"
- "Differential relaying"
− - "Energy reducing maintenance switch (ERMS) with local status indicator"
− - "Energy reducing active arc flash mitigation system"
− - "Instantaneous trip setting"
− - "Instantaneous override"
− - "Approved equivalent means"
−default: "Zone-selective interlocking (ZSI)"
+ - "Energy-reducing active arc-flash mitigation system"
+ - "Instantaneous trip setting below the available arcing current"
+default: derived
```
−### Circuit breakers rated 1200A or more shall be furnished with an arc energy reduction method complying with NFPA 70 Article 240.87.
+### 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. {note}
−### Zone-selective interlocking allows upstream breakers to delay tripping only when a downstream breaker detects the fault, reducing arc flash energy at the upstream equipment while maintaining coordination, and does not require any mode switching for maintenance activities. {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. {note}
−## Feeder Circuit Breakers {toc}
+### 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.
−### Feeder breaker sizes, quantities, and trip ratings shall be [[drawing: as indicated on the breaker schedule]].
+### 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.
−### The feeder breaker type shall be as indicated in the datasheet.
+### 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.
+## Breaker Accessories {toc}
+
+### The accessories furnished on every breaker shall be as indicated in the datasheet.
+
```datasheet
−label: Feeder Breaker Type
−type: select
+label: Accessories on Every Breaker
+type: checkbox
options:
− - "Power circuit breaker (drawout)"
− - "Insulated case circuit breaker (drawout)"
−default: "Power circuit breaker (drawout)"
+ - "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"
+default:
+ - "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"
+ - "Padlocking provisions in the open position and in the withdrawn position"
+constraint: all_of
```
−### The feeder breaker trip units shall be as indicated in the datasheet.
+### 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 [[drawing: the one-line diagram]].
+### 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. {note}
+
+### 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 [[drawing: the one-line diagram]], and the circuit shall be tested through its initiating device before the switchgear is accepted.
+
+### 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.
+
+# Control Power and Control Wiring {toc}
+
+## Control Power Source {toc}
+
+### 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.
+
```datasheet
−label: Feeder Breaker Trip Units
−type: select
−drawing_ref: "breaker schedule"
+label: Control Power Source
+type: radio
options:
− - "Electronic trip - LSI"
− - "Electronic trip - LSIG"
−default: deferred
+ - "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"
```
−### The breaker accessories furnished on all breakers shall be as indicated in the datasheet.
+### 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 [[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. {note}
+### 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.
+
+### 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 [[sync/dc-battery-systems]] for that load, and the DC feed shall enter the switchgear through a fused disconnect in a control compartment.
+
+### 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.
+
+### 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.
+
+## Control Voltage {toc}
+
+### The control voltage of the switchgear shall be as indicated in the datasheet.
+
```datasheet
−label: Breaker Accessories (All Breakers)
−type: checkbox
+label: Control Voltage
+type: select
+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"
options:
− - "Auxiliary contacts (1a + 1b minimum)"
− - "Shunt trip"
− - "Undervoltage release"
− - "Mechanical interlock (paired breakers)"
− - "Kirk key interlock"
− - "Motor operator with remote close/trip"
− - "Breaker position indication (drawout connected/test/disconnected)"
−default:
− - "Auxiliary contacts (1a + 1b minimum)"
− - "Breaker position indication (drawout connected/test/disconnected)"
+ - "120 V AC"
+ - "240 V AC"
+ - "24 V DC"
+ - "48 V DC"
+ - "125 V DC"
+ - "250 V DC"
+default: derived
```
−### Auxiliary contacts shall be provided on every breaker regardless of other accessory selections.
+### 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.
−### Auxiliary contacts shall indicate breaker open/close status and shall be wired to terminal blocks accessible without removing the breaker from its compartment.
+## Control Wiring {toc}
−## Breaker Drawout Mechanism {toc}
+### 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.
−### All breakers shall be fully drawout and interchangeable within a given frame size.
+### 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.
−### A manual racking mechanism shall allow movement between connected, test, and disconnected positions.
+### 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.
−### The racking mechanism shall include a mechanical position indicator visible from the front of the switchgear and a means to padlock the breaker in any of the three positions.
+### 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.
−### Self-aligning primary disconnects shall engage automatically when the breaker is racked to the connected position.
+### 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.
−### Secondary disconnects for control wiring shall engage at the test position.
+### 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.
−### It shall be possible to operate the breaker electrically in the test position for trip testing without energizing the primary circuit.
+# Protective Relays, Metering, and Communications {toc}
−# Protective Relaying {toc}
+## Protective Relays {toc}
−## The protective relay functions furnished shall be as indicated in the datasheet.
+### The protective relay functions furnished at the switchgear beyond those carried by the breaker trip units shall be as indicated in the datasheet.
```datasheet
label: Protective Relay Functions
type: checkbox
+drawing_ref: "the one-line diagram"
options:
− - "Not applicable — protection provided by breaker trip units only"
− - "Overcurrent (50/51)"
− - "Ground fault (50G/51G)"
+ - "Undervoltage and overvoltage (27/59)"
+ - "Underfrequency and overfrequency (81)"
+ - "Reverse power (32)"
+ - "Bus overcurrent (50/51)"
- "Bus differential (87B)"
− - "Under/overvoltage (27/59)"
− - "Under/overfrequency (81)"
- "Breaker failure (50BF)"
− - "Reverse power (32)"
−default:
− - "Overcurrent (50/51)"
− - "Ground fault (50G/51G)"
+ - "Synchronism check (25)"
+ - "Lockout relay (86)"
+default: deferred
+constraint: all_of
```
−## The relay complement is set by the coordination study and the system grounding arrangement; on many low-voltage line-ups the electronic trip units carry the full protection scheme and no discrete relays are furnished, which the "Not applicable" value records. {note}
+### 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.
−## Relay settings shall be [[drawing: as indicated on the relay setting schedule]].
+### 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 [[sync/protective-coordination-study]].
−## Protective relays shall comply with IEEE C37.90 and shall be microprocessor-based with digital displays, self-diagnostics, and event recording.
+### 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. {note}
−## Relays shall be tested per IEEE C37.90.1 for surge withstand capability.
+## Instrument Transformers {toc}
−## Protection coordination study shall be performed per [[sync/protective-coordination-study]].
+### 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.
−# Metering and Instrumentation {toc}
+### 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 [[sync/electrical-power-monitoring]] requires for the metering point.
−## Instrument Transformers {toc}
+### 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.
−### Current transformers shall comply with IEEE C57.13.
−### Accuracy class shall be appropriate for the connected metering:
+## Metering Provisions {toc}
−- Revenue metering: Class 0.3 accuracy
−- Protective relaying: Class C200 or higher
−- General monitoring: Class 0.6 accuracy
+### The metering furnished within the switchgear shall be as indicated in the datasheet.
−### Current transformers for metering and relaying shall be provided on separate cores.
+```datasheet
+label: Metering Provisions
+type: select
+options:
+ - "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"
+```
−### CTs shall not be shared between metering and protection functions.
+### 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 [[sync/electrical-power-monitoring]] wants from it, so the field asserts no default. {note}
−## Power Monitoring {toc}
+### Meters, their accuracy class, their current transformers, and their communications shall comply with [[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.
−### The metering type and extent shall be as indicated in the datasheet.
+### Where [[parameter: 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 [[sync/electrical-power-monitoring]].
+## Utility Metering Compartment {toc}
+
+### The utility metering compartment shall be as indicated in the datasheet.
+
```datasheet
−label: Metering Type
+label: Utility Metering Compartment
type: select
+derived: "the service configuration and the serving utility's metering requirements as confirmed in writing"
options:
− - "No metering"
− - "Digital multifunction meter at the main"
− - "Digital multifunction meter at the main and each feeder"
− - "Revenue-grade metering per utility requirements"
+ - "Not furnished"
+ - "Utility current transformer compartment ahead of the main, cold sequence"
+ - "Utility current transformer compartment after the main, hot sequence"
+default: derived
```
−### Metering extent is an Owner and energy-code decision rather than a property of the switchgear, so the field carries no default; see the submetering clause below for the code trigger. {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. {note}
−### The meter functions provided shall be as indicated in the datasheet.
+### 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.
+## Surge Protective Device Provisions {toc}
+
+### A surge protective device shall be furnished at the lineups indicated on [[drawing: the one-line diagram]], and the device, its type, its ratings, its protection modes, and its lead length shall comply with [[sync/surge-protective-devices]].
+
+### Where a surge protective device is furnished at a lineup, its mounting arrangement shall be as indicated in the datasheet.
+
```datasheet
−label: Meter Functions
−type: checkbox
+label: Surge Protective Device Mounting Arrangement
+type: radio
options:
− - "Voltage (L-L, L-N all phases)"
− - "Current (per phase and neutral)"
− - "Power factor (per phase and total)"
− - "kW / kVA / kVAR (demand and instantaneous)"
− - "kWh / kVARh energy accumulation"
− - "Harmonics (THD per phase, individual to 31st)"
− - "Min/max recording with time stamp"
− - "Waveform capture"
−default:
− - "Voltage (L-L, L-N all phases)"
− - "Current (per phase and neutral)"
− - "Power factor (per phase and total)"
− - "kW / kVA / kVAR (demand and instantaneous)"
− - "kWh / kVARh energy accumulation"
+ - "Integral, factory-installed in a compartment of the switchgear"
+ - "External, mounted adjacent to the switchgear and connected through a dedicated breaker"
```
−### The metering communication protocol shall be as indicated in the datasheet.
+### 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. {note}
+### 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.
+
+## Communications Protocol {toc}
+
+### The communications protocol of the switchgear network shall be as indicated in the datasheet.
+
```datasheet
−label: Metering Communication Protocol
+label: Communications Protocol
type: select
options:
− - "No communications"
− - "Modbus RTU (RS-485)"
− - "Modbus TCP/IP (Ethernet)"
− - "BACnet IP"
+ - "No network, dry contacts only"
+ - "Modbus RTU"
+ - "Modbus TCP"
+ - "BACnet/IP"
+ - "BACnet MS/TP"
+ - "EtherNet/IP"
- "DNP3"
+ - "IEC 61850"
```
−### The protocol is set by whatever the receiving building management or power monitoring system speaks, so it carries no default and shall be confirmed before submittal. {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 [[sync/building-automation-system]], and one reporting to a power monitoring system speaks what that system reads under [[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. {note}
−### Where building energy code requires submetering (ASHRAE 90.1 Section 8.4.3 or local amendments), meter data shall be accessible via the selected communication protocol for integration with the building management system.
+### Where a network is furnished, the devices connected to it shall be as indicated in the datasheet.
−### The Contractor shall coordinate communication wiring and protocols with [[sync/building-automation-system]].
+```datasheet
+label: Networked Devices
+type: checkbox
+options:
+ - "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"
+constraint: all_of
+```
−# Finish and Identification {toc}
+### 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.
−## The enclosure finish color shall be as indicated in the datasheet.
+### 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.
+### 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.
+
+### 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.
+
+# Bus {toc}
+
+## Phase Bus Material {toc}
+
+### The phase bus material shall be as indicated in the datasheet.
+
```datasheet
+label: Phase Bus Material
+type: radio
+options:
+ - "Copper"
+ - "Aluminum"
+default: "Copper"
+```
+
+### 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. {note}
+
+### Where copper bus is selected, it shall be copper bus bar conforming to ASTM B187 with a conductivity of not less than 98% IACS.
+
+### 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.
+
+## Bus Plating {toc}
+
+### The bus plating shall be as indicated in the datasheet.
+
+```datasheet
+label: Bus Plating
+type: radio
+options:
+ - "Unplated, with plated joint contact surfaces"
+ - "Tin-plated over the full length"
+ - "Silver-plated over the full length"
+default: manufacturer
+```
+
+### The manufacturer shall state the plating in the product data.
+
+### 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. {note}
+
+### Plating shall be continuous over every bolted joint contact surface, every stationary primary disconnect, every breaker runback, and every splice at a shipping split.
+
+## Bus Sizing Basis {toc}
+
+### The basis on which the bus cross-section is sized shall be as indicated in the datasheet.
+
+```datasheet
+label: Bus Sizing Basis
+type: select
+options:
+ - "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"
+default: "Temperature rise per IEEE C37.20.1"
+```
+
+### 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. {note}
+
+### 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.
+
+## Bus Insulation {toc}
+
+### The bus insulation shall be as indicated in the datasheet.
+
+```datasheet
+label: Bus Insulation
+type: radio
+options:
+ - "Bare bus in an isolated bus compartment"
+ - "Insulated bus with flame-retardant sleeving or coating and insulating boots at the joints"
+default: "Bare bus in an isolated bus compartment"
+```
+
+### 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. {note}
+
+### 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.
+
+## Bus Joints and Bracing {toc}
+
+### 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).
+
+### 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.
+
+### 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.
+
+### 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.
+
+### 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.
+
+## Bus Extension Provisions {toc}
+
+### The provisions for future extension of the lineup shall be as indicated in the datasheet.
+
+```datasheet
+label: Bus Extension Provisions
+type: select
+options:
+ - "No extension provisions"
+ - "Extension provisions at one end"
+ - "Extension provisions at both ends"
+default: "No extension provisions"
+```
+
+### 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. {note}
+
+### Where extension provisions are furnished, the end at which they are furnished shall be as indicated on [[drawing: the electrical plans]], and the through-bus to that end shall carry the rating the extension is to be made at.
+
+# Structure and Enclosure {toc}
+
+## Compartmentalization {toc}
+
+### 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.
+
+### 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.
+
+### 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.
+
+### The compartment barriers furnished beyond those the listing requires shall be as indicated in the datasheet.
+
+```datasheet
+label: Compartment Barriers Beyond the Listing
+type: checkbox
+options:
+ - "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"
+constraint: all_of
+```
+
+### 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. {note}
+
+### Barriers shall be grounded metal or an insulating material rated for the system voltage, and a barrier required by the listing or by [[sync/electrical-service-entrance]] for the service disconnect grouping shall be furnished whatever the datasheet selects.
+
+## Enclosure Type {toc}
+
+### The enclosure type shall be as indicated in the datasheet.
+
+```datasheet
+label: Enclosure Type per NEMA 250
+type: select
+options:
+ - "Type 1"
+ - "Type 1 gasketed"
+ - "Type 2"
+ - "Type 3R"
+ - "Type 12"
+default: "Type 1"
+```
+
+### 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. {note}
+
+### 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.
+
+### 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.
+
+### Switchgear installed indoors where airborne dust, lint, or fibers accumulate shall have an enclosure of Type 12 or Type 1 gasketed.
+
+### Switchgear installed indoors where dripping or light splashing of a non-corrosive liquid occurs shall have an enclosure of Type 2 or Type 12.
+
+### 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.
+
+### 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.
+
+### 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. {note}
+
+## Outdoor Housing {toc}
+
+### Where the switchgear is installed outdoors, the housing arrangement shall be as indicated in the datasheet.
+
+```datasheet
+label: Outdoor Housing Arrangement
+type: select
+options:
+ - "Non-walk-in"
+ - "Walk-in with a front aisle"
+ - "Walk-in with a common aisle between two facing lineups"
+```
+
+### 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. {note}
+
+### 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.
+
+### 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.
+
+## Enclosure Material and Finish {toc}
+
+### The enclosure material shall be as indicated in the datasheet.
+
+```datasheet
+label: Enclosure Material
+type: select
+options:
+ - "Painted steel"
+ - "Type 304 stainless steel"
+ - "Type 316 stainless steel"
+default: "Painted steel"
+```
+
+### 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. {note}
+
+### 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.
+
+### 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.
+
+### The finish color shall be as indicated in the datasheet.
+
+```datasheet
label: Finish Color
−type: text
−default: "ANSI 61 gray"
+type: select
+options:
+ - "ANSI 61 light gray"
+ - "ANSI 49 medium gray"
+ - "ANSI 70 sky gray"
+ - "Custom color matched to a sample furnished by the Owner"
+default: "ANSI 61 light gray"
```
−## ANSI 61 light gray is the established North American switchgear finish and is carried as the default; a different color is a purely cosmetic Owner election. {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. {note}
−## Enclosure shall receive a minimum two-coat paint system: corrosion-resistant primer and manufacturer's standard polyester powder coat finish.
+## Section Accessibility {toc}
−## Minimum total dry film thickness shall be 3 mils (75 microns).
+### The accessibility of the lineup shall be as indicated in the datasheet.
−## For outdoor installations or environments classified C3 or higher, an enhanced paint system with a minimum of 5 mils dry film thickness shall be applied.
+```datasheet
+label: Section Accessibility
+type: radio
+options:
+ - "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"
+default: "Rear-connected, with breaker compartments at the front and cable compartments at the rear"
+```
−## All internal structural members shall receive the same corrosion treatment as exterior surfaces.
+### 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. {note}
−## Labeling {toc}
+### 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.
−### Manufacturer shall provide engraved phenolic nameplates for the switchgear assembly and each individual device.
−### Nameplates shall identify:
+### 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.
−- Switchgear designation and one-line reference
−- Bus ratings (voltage, continuous current, short-circuit)
−- Individual breaker designation, frame size, and trip rating
−- Current transformer ratios and accuracy class
−- Arc flash warning labels per NFPA 70E and IEEE 1584
+### 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.
−### The nameplate material shall be as indicated in the datasheet.
+## Incoming Connection and Cable Compartments {toc}
+### The incoming connection to the switchgear shall be as indicated in the datasheet.
+
```datasheet
−label: Nameplate Material
+label: Incoming Connection
+type: select
+drawing_ref: "the one-line diagram"
+options:
+ - "Cable"
+ - "Busway"
+ - "Bus from an adjacent assembly or a close-coupled transformer"
+default: deferred
+```
+
+### 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. {note}
+
+### 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.
+
+### 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 [[drawing: the electrical plans]], and matched to the busway furnished under [[sync/busway]].
+
+### 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.
+
+### 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.
+
+### 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 [[sync/wireways-and-auxiliary-gutters]].
+
+## Conduit Entry {toc}
+
+### Conduit entry to the switchgear shall be as indicated in the datasheet.
+
+```datasheet
+label: Conduit Entry
type: radio
+drawing_ref: "the electrical plans"
options:
− - "Laminated phenolic (indoor)"
− - "Stainless steel (outdoor or corrosive)"
− - "Aluminum (anodized)"
−default: "Laminated phenolic (indoor)"
+ - "Top entry"
+ - "Bottom entry"
+ - "Top and bottom entry"
+default: deferred
```
−### Mimic bus diagram shall be provided on the front of the switchgear showing the bus configuration, breaker positions, and instrument transformer locations.
+### 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.
−### Equipment labeling shall follow [[sync/equipment-labeling]] conventions.
+### 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.
+# Arc-Flash Mitigation and Maintenance Safety {toc}
+
+## Arc-Resistant Construction {toc}
+
+### Arc-resistant construction shall be as indicated in the datasheet.
+
+```datasheet
+label: Arc-Resistant Construction
+type: select
+options:
+ - "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"
+```
+
+### 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. {note}
+
+### 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 [[sync/short-circuit-study]], and the exhaust plenum and its discharge location shall be shown on the shop drawings and coordinated with [[sync/electrical-rooms]].
+
+### 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.
+
+### 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. {note}
+
+## Maintenance Safety Provisions {toc}
+
+### The maintenance safety provisions furnished shall be as indicated in the datasheet.
+
+```datasheet
+label: Maintenance Safety Provisions
+type: checkbox
+options:
+ - "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"
+constraint: all_of
+```
+
+### 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. {note}
+
+### 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 [[sync/arc-flash-study]], placed so that each is read before a door is opened or a cover removed.
+
+# Identification {toc}
+
+## Nameplates, arc-flash warning labels, available fault current markings, and source identification shall comply with [[sync/equipment-labeling]] for material, lettering, attachment, and content, and the text shall be that listed on the nameplate schedule.
+
+## 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.
+
+## 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.
+
+## Each rear cable compartment door or cover shall carry the designation of the breaker whose terminations lie behind it.
+
+## 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.
+
+## 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.
+
+## 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.
+
+## Whether a mimic bus is furnished shall be as indicated in the datasheet.
+
+```datasheet
+label: Mimic Bus
+type: radio
+options:
+ - "Not furnished"
+ - "Furnished"
+default: "Not furnished"
+```
+
+## 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. {note}
+
# Testing {toc}
## Factory Tests {toc}
−### The manufacturer shall perform the following production tests on the completed switchgear assembly per IEEE C37.51:
+### 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.
−- 60 Hz dielectric withstand test on primary bus
−- Insulation resistance measurement on each phase and neutral bus
−- Mechanical operation of each circuit breaker (minimum 5 open/close cycles)
−- Electrical operation of each circuit breaker (trip and close)
−- Ground fault sensing system functional test
−- Control wiring continuity verification
−- Current transformer ratio and polarity test
−- Protective relay functional test (verify trip at set values)
−- Visual and dimensional inspection
+### Factory test witnessing shall be as indicated in the datasheet.
−### The factory acceptance test witnessing requirement shall be as indicated in the datasheet.
−
```datasheet
−label: Factory Acceptance Test
+label: Factory Test Witnessing
type: radio
options:
− - "Witnessed by Owner's representative"
− - "Unwitnessed with certified test report"
− - "Not required beyond standard production tests"
−default: "Witnessed by Owner's representative"
+ - "Witnessed by the Owner's representative"
+ - "Certified test report without witnessing"
+default: "Certified test report without witnessing"
```
−### Where witnessed factory testing is specified, the manufacturer shall provide a minimum of two weeks advance notice of test readiness.
+### 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.
−### Where witnessed factory testing is specified, test procedures shall be submitted for review prior to testing.
+### 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. {note}
## Field Acceptance Tests {toc}
−### Where independent NETA testing is indicated in the datasheet, Contractor shall engage a qualified independent testing firm to perform acceptance testing per NETA ATS.
+### 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 [[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 tests shall include as a minimum:
+```datasheet
+label: Field Acceptance Tests
+type: checkbox
+options:
+ - "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"
+default:
+ - "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"
+ - "Trip unit and relay settings verification against the coordination study"
+ - "Zone-selective interlocking or other arc energy reduction performance test per NFPA 70 240.87(C)"
+ - "Control power loss simulation with every breaker holding its position and every trip circuit proven to trip on the capacitor trip or battery source"
+ - "Current transformer ratio and polarity verification"
+ - "Neutral-to-ground separation verification on every lineup that is not service equipment"
+constraint: all_of
+```
−- Visual and mechanical inspection of all sections
−- Insulation resistance testing (phase-to-phase and phase-to-ground)
−- Contact resistance measurement on all bolted bus connections
−- Circuit breaker operational testing (mechanical and electrical)
−- Protective relay calibration verification
−- Primary current injection testing of all trip functions (long-time, short-time, instantaneous, ground fault pickup and time delay)
−- Current transformer ratio and polarity verification
−- Metering accuracy verification
−- Ground impedance measurement per IEEE 81
−- Functional testing of all control circuits, interlocks, and alarms
+### 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.
−### The field testing scope shall be as indicated in the datasheet.
+### 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.
+## Start-Up and Infrared Inspection {toc}
+
+### Manufacturer start-up services shall be as indicated in the datasheet.
+
```datasheet
−label: Field Testing Requirements
+label: Manufacturer Start-Up Services
type: radio
options:
− - "NETA acceptance testing and manufacturer startup"
− - "NETA acceptance testing without manufacturer startup"
− - "Manufacturer startup without independent NETA testing"
−default: "NETA acceptance testing and manufacturer startup"
+ - "Not required"
+ - "Manufacturer's field service engineer present for energization, trip unit and relay commissioning, and the first transfer"
```
−### The infrared thermographic inspection scope shall be as indicated in the datasheet.
+### 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. {note}
+### Infrared thermographic inspection shall be as indicated in the datasheet.
+
```datasheet
label: Infrared Thermographic Inspection
−type: radio
+type: select
options:
− - "Initial scan within 90 days of energization, follow-up at 11 months"
− - "Initial scan within 90 days of energization"
- "Not required"
−default: "Initial scan within 90 days of energization, follow-up at 11 months"
+ - "One inspection within 90 days of energization"
+ - "One inspection within 90 days of energization and a second at eleven months"
```
−### Acceptance testing shall occur after installation is complete and before the equipment is energized.
+### 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.
−### Where an infrared scan is indicated in the datasheet, it shall be performed under normal operating load conditions (minimum 40% of rated load).
+### 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. {note}
−### All connections exceeding 10°C rise above ambient shall be reported and corrected.
+# Installation {toc}
−### A follow-up scan at 11 months captures connections that may loosen during the initial thermal cycling period. {note}
+## Location and Working Space {toc}
−# Installation {toc}
+### The room in which the switchgear is installed shall satisfy [[sync/electrical-rooms]] where that room is an electrical room.
−## Concrete Housekeeping Pad {toc}
+### 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.
−### See [[sync/concrete-pads]] for construction requirements. {note}
+### 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.
−### Switchgear shall be mounted on a reinforced concrete housekeeping pad extending a minimum of 3 in. beyond the base of the equipment on all sides.
+### 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.
−### Pad shall be a minimum of 4 in. above finished floor for indoor installations and 6 in. above finished grade for outdoor installations.
+### Working space shall not be used for storage at any time, and a withdrawn breaker shall not be left standing in it.
−### The Contractor shall coordinate pad dimensions, conduit penetrations, and anchor bolt locations with equipment shop drawings prior to concrete placement.
+### The switchgear shall be set on a concrete housekeeping pad constructed under [[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.
−## Equipment Setting {toc}
+### 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.
−### Before energizing, the Contractor shall verify the following:
+### The switchgear shall be anchored to the pad as indicated on [[drawing: 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.
−- All shipping restraints and temporary grounds removed
−- Bus joint torque verified per manufacturer's specifications using calibrated torque wrench
−- All circuit breakers rack and operate freely in all three positions
−- Conduit terminations sealed and cable connections torqued
−- Space heaters energized (outdoor or unconditioned installations)
−- Working clearances per NFPA 70 Article 110.26 are maintained
+## Setting and Assembly {toc}
−### Contractor shall comply with manufacturer's installation instructions and applicable rigging requirements.
+### 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.
−### The Contractor shall remove all temporary shipping braces, blocking, and desiccants prior to final assembly.
+### 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.
−### The Contractor shall verify section alignment and bolt all sections together per manufacturer's torque specifications.
+### 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.
−## Working Clearance {toc}
+### 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.
−### Minimum working space shall be maintained per NFPA 70 Article 110.26 based on the nominal voltage and accessibility configuration:
+### 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.
−| Voltage | Condition 1 (exposed on one side) | Condition 2 (exposed on both sides) |
−|---------|-----------------------------------|--------------------------------------|
−| 0-150V | 36 in. | 36 in. |
−| 151-600V | 36 in. | 48 in. |
+### 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.
−### Working space shall not be used for storage.
+## Conductor Terminations {toc}
−### Dedicated electrical space above and below the equipment shall be maintained per NFPA 70 Article 110.26(E).
+### The main and feeder lugs shall be of the type indicated in the datasheet.
+```datasheet
+label: Main and Feeder Lug Type
+type: radio
+options:
+ - "Mechanical set-screw lugs"
+ - "Compression lugs"
+default: manufacturer
+```
+
+### The manufacturer shall state the lug type furnished in the product data.
+
+### 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. {note}
+
+### 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.
+
+### 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.
+
+### 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.
+
+### Conductor selection and installation shall comply with [[sync/conductors-and-cables]], and raceways shall comply with [[sync/raceways-and-conduit]].
+
# Delivery, Storage, and Handling {toc}
−## Switchgear shall be shipped in the largest factory-assembled sections that can be transported to and within the installation site.
+## 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.
−## The Contractor shall verify all pathway dimensions (doors, hallways, elevator shafts) between the delivery point and the final installation location prior to ordering.
+## 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.
−## Equipment shall be stored indoors in a clean, dry location.
+## 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.
−## Where indoor storage is not available, the manufacturer shall provide weatherproof packaging.
+## 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.
−## Condensation heaters shall be connected and energized during storage if the equipment will be stored for more than 30 days or if the storage environment is not climate-controlled.
+## 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.
+## 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.
+
+## 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.
+
# Warranty {toc}
−## The warranty period shall be as indicated in the datasheet.
+## 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.
```datasheet
−label: Warranty Period
+label: Manufacturer's Warranty Period
+type: range
+unit: years
+options:
+ min: 1
+ max: 5
+ setpoints: [1, 2, 3, 5]
+constraint: min
+```
+
+## 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.
+
+## The warranty period shall commence on the date indicated in the datasheet.
+
+```datasheet
+label: Warranty Commencement
type: select
options:
− - "1 year from substantial completion"
− - "2 years from substantial completion"
− - "3 years from substantial completion"
− - "5 years from substantial completion"
−default: "1 year from substantial completion"
+ - "Date of substantial completion"
+ - "Date of energization"
+ - "Date of shipment"
```
−## The extended warranty coverage purchased by the Owner shall be as indicated in the datasheet.
+## 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. {note}
+## The warranty coverage scope shall be as indicated in the datasheet.
+
```datasheet
−label: Extended Warranty Coverage
−type: checkbox
+label: Warranty Coverage Scope
+type: radio
options:
- "Parts only"
- "Parts and labor"
− - "Emergency response (24/7 with 4-hour commitment)"
− - "Scheduled preventive maintenance (annual)"
```
−## Extended coverage beyond the base warranty is an Owner purchase decision with a direct cost, so the field carries no default. {note}
+## 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.
−## Warranty shall cover defects in materials and workmanship under normal use and service conditions.
+## 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.
−## The manufacturer shall maintain a service organization capable of providing emergency replacement parts and field service within 24 hours during the warranty period.
+# Spare Parts and Handling Equipment {toc}
−# Spare Parts {toc}
+## 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.
−## The quantity of spare circuit breakers furnished shall be as indicated in the datasheet.
−
```datasheet
−label: Spare Breakers
−type: radio
+label: Spare Parts to Be Furnished
+type: checkbox
options:
− - "None"
− - "One spare of each frame size"
− - "10% of each frame size (minimum one)"
+ - "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"
+default:
+ - "One set of control fuses of each type and rating installed"
+ - "Two sets of keys for every lock and key interlock"
+constraint: all_of
```
−## A spare drawout breaker is a substantial line-item cost that turns on the Owner's tolerance for outage duration and on local availability, so the field carries no default. {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. {note}
−## Spare breakers shall be of the same type, rating, and configuration as the installed breakers and shall be fully interchangeable.
+## 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.
−## Spare breakers shall be stored in a manufacturer-provided storage cabinet or on a breaker storage truck, located in the electrical room.
+## 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.
−## Manufacturer shall provide the following additional spare parts: one set of replacement fuses for each fuse type and rating installed, one set of replacement indicating lights for each type installed, one set of racking handle, breaker test plugs, and portable closing tools, and one complete set of keys for all locks.
+## The breaker handling equipment furnished with the switchgear shall be as indicated in the datasheet.
+
+```datasheet
+label: Breaker Handling Equipment
+type: checkbox
+options:
+ - "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"
+default:
+ - "Portable breaker lift truck that reaches the highest compartment of the tallest lineup"
+ - "Racking handle and tool set for each lineup"
+constraint: all_of
+```
+
+## 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. {note}
+
+## 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.
+
+```datasheet
+label: Operator Training Period
+type: range
+unit: hours
+options:
+ min: 0
+ max: 16
+ setpoints: [0, 2, 4, 8, 16]
+default: 4
+constraint: min
+```