Busway
Remade from scratch to the authoring rules: defaults asserted only where four of five projects would choose them, and scope boundaries matched to the neighboring standards
Showing changes from Rev 3
to Rev 4
in Busway.
---
title: Busway
category: Electrical
−toc_depth: 3
description: >
− When to use: Feeder and plug-in busway systems rated 600 V or less, UL 857-listed, for commercial, industrial, and data center power distribution where high-current bus runs, flexible load tap-off, or vertical riser distribution are required.
− Not intended for: Medium-voltage metal-enclosed bus above 600 V (governed by IEEE C37.23), low-ampere lighting trolley duct, cable tray, raceway and conductor wiring methods, or factory bus connections internal to switchboards and panelboards.
+ When to use: Feeder and plug-in busway rated 600 V and below, listed to UL 857 and built to NEMA BU 1, used as a feeder, a riser, a transformer or switchboard connection, or an overhead distribution run that loads tap into at intervals. Covers the bus run as a listed system: the ratings, the bus bars and their joints, the housing and its enclosure type, the elbows, tees, offsets, flanged ends, tap boxes, end closures, expansion fittings, and fire-rated penetration fittings, the hangers and supports, identification, factory and field testing, installation, warranty, and spares, for three-phase and single-phase AC systems in indoor and outdoor locations.
+
+ Not intended for: the plug-in units themselves, including fusible-switch and circuit-breaker tap boxes and their overcurrent devices ([[sync/feeder-busway-plug-in-units]]); the switchboard, substation secondary, transformer, panelboard, or generator the busway terminates at and the flange that equipment furnishes ([[sync/low-voltage-switchboards]], [[sync/secondary-unit-substations]], [[sync/panelboards]]); the conductors landed in a cable tap box and their terminations ([[sync/conductors-and-cables]]); the through-penetration firestop system installed around the run at a rated assembly ([[sync/firestopping]]); the design of seismic restraint for the supports ([[sync/vibration-isolation-and-seismic-restraint]]); the equipment grounding conductors and the bonding of the system the busway is part of ([[sync/grounding-and-bonding]]); conduit and tubing ([[sync/raceways-and-conduit]]); open-top tray ([[sync/cable-tray]]); enclosed troughs and gutters ([[sync/wireways-and-auxiliary-gutters]]); metal-enclosed bus above 600 V built to IEEE C37.23; lighting and trolley busway; busway in hazardous classified locations; and the short-circuit, coordination, and arc-flash studies that establish the ratings the busway is ordered to ([[sync/short-circuit-study]], [[sync/protective-coordination-study]], [[sync/arc-flash-study]]).
---
# Scope {toc}
−## This standard covers the materials, ratings, construction, testing, and installation of busway systems rated 600 V or less and 6000 A or less for power distribution. {note}
+## This standard governs the busway as a listed system: the straight lengths and the bus bars inside them, the joints between lengths, the housing and its enclosure type, the fittings that turn, branch, reduce, terminate, and close the run, the expansion and fire-rated penetration fittings, the hangers that carry the run, and the field work that puts the run into service. {note}
−## Busway is a prefabricated assembly of bus bars, supports, and an enclosing housing, manufactured in standard straight lengths and fittings that bolt together to form a continuous distribution run. Compared with cable in raceway, busway delivers high current in a compact cross-section, dissipates heat efficiently, and allows load tap-off at intervals without cutting conductors, which makes it the preferred method for risers and high-density feeders. {note}
+## Busway is a factory assembly of bus bars held in an enclosing housing, made in straight lengths and fittings that bolt together into a continuous run, with the joint hardware and the plug-in openings part of the listed product. It carries the current a cable bundle would need several parallel sets to carry, in a cross-section that fits a riser shaft or an overhead rack, and a plug-in run lets a load be tapped at any opening without cutting a conductor. {note}
−## Busway shall comply with UL 857 and the applicable provisions of NEMA BU 1 for the listed type, voltage, and ampere rating specified.
+## Two constructions share the UL 857 listing and this standard. Feeder busway is a closed run from one piece of equipment to another, with no openings along its length; plug-in busway carries openings at intervals along its length that accept the plug-in units furnished under [[sync/feeder-busway-plug-in-units]]. A run is often both: feeder sections from the source and plug-in sections where the loads are. {note}
−## This standard applies to feeder busway, plug-in busway, and the associated fittings, elbows, tees, expansion fittings, end closures, and plug-in tap units that complete the system. {note}
+## The run is one listed product. Its short-circuit current rating, its enclosure type, and its ground path are properties of the straight lengths, the joints, and the fittings together, and a fitting from another product series, a field-cut length, or a joint made with substitute hardware removes the run from the condition under which it was rated. {note}
−## This standard does not cover the following, which are specified elsewhere: {note}
+## The following are governed elsewhere and are outside this standard: {note}
−- Medium-voltage metal-enclosed bus above 600 V, which uses a different listing, dielectric design, and short-circuit basis (governed by IEEE C37.23)
−- Low-ampere lighting busway (trolley duct), whose construction, ratings, and tap method differ fundamentally from power busway
−- The bus connections internal to switchboards, panelboards, transformers, or generators where busway terminates, which are governed by the standard for that terminating equipment (see [[sync/low-voltage-switchboards]], [[sync/panelboards]])
+- the plug-in units, including fusible-switch and circuit-breaker tap boxes, their overcurrent devices, and their interlocks, under [[sync/feeder-busway-plug-in-units]]
+- the switchboard or substation secondary the busway terminates at, and the busway flange that equipment furnishes under its assembly listing, under [[sync/low-voltage-switchboards]] and [[sync/secondary-unit-substations]]
+- the panelboard the busway terminates at, under [[sync/panelboards]]
+- the conductors landed in a cable tap box and their terminations, under [[sync/conductors-and-cables]]
+- the through-penetration firestop system installed around the run where it passes through a rated wall or floor, under [[sync/firestopping]]
+- the design of the seismic restraint of the hangers and supports, under [[sync/vibration-isolation-and-seismic-restraint]]
+- the equipment grounding conductors and the bonding of the system the busway is part of, under [[sync/grounding-and-bonding]]
+- conduit, cable tray, and wireway, under [[sync/raceways-and-conduit]], [[sync/cable-tray]], and [[sync/wireways-and-auxiliary-gutters]]
+- nameplate and label material, lettering, and attachment, under [[sync/equipment-labeling]]
+- the short-circuit, coordination, and arc-flash studies, under [[sync/short-circuit-study]], [[sync/protective-coordination-study]], and [[sync/arc-flash-study]]
+- field acceptance testing method, instruments, and the compiled test report, under [[sync/electrical-acceptance-testing]]
−## Related distribution and protection requirements are addressed in [[sync/low-voltage-switchboards]], [[sync/panelboards]], [[sync/conductors-and-cables]], [[sync/grounding-and-bonding]], and [[sync/equipment-labeling]]. {note}
+## Metal-enclosed bus above 600 V, built to IEEE C37.23, is a different product with a different listing and dielectric basis, and lighting and trolley busway are low-ampere products with a different construction and tap method; neither is covered by any standard in this library. {note}
+## Busway, its fittings, and its joint hardware shall comply with NEMA BU 1 and shall be listed and labeled to UL 857 by a Nationally Recognized Testing Laboratory.
+
+## The routing, the mounting elevation, and the fitting arrangement of each run shall be as indicated on [[drawing: the busway routing plans and riser diagram]].
+
+## Where a value stated on the one-line diagram for a particular run differs from the datasheet selection under this standard, the one-line diagram shall govern for that run.
+
# Referenced Standards {toc}
−## The following standards are referenced in this document; the edition adopted by the Authority Having Jurisdiction governs where an edition conflict exists. {note}
+## 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 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 857 | Standard for Busway |
−| NEMA BU 1 | Busways, 600 V or Less |
−| NEMA BU 1.1 | Handling, Installation, Operation, and Maintenance of Busway |
−| NFPA 70 | National Electrical Code (Article 368 — Busways; Article 300 — Wiring Methods) |
+| UL 857 | Busways |
+| NEMA BU 1 | Busways |
+| NEMA BU 1.1 | General Instructions for Handling, Installation, Operation, and Maintenance of Busway Rated 600 Volts or Less |
+| NEMA 250 | Enclosures for Electrical Equipment (1000 Volts Maximum) |
+| NFPA 70 | National Electrical Code (Articles 110, 230, 250, 300, and 368) |
| NFPA 70E | Standard for Electrical Safety in the Workplace |
−| IEEE C37.23 | Guide for Metal-Enclosed Bus |
−| IBC | International Building Code |
−| ASCE 7 | Minimum Design Loads and Associated Criteria for Buildings and Other Structures |
+| ANSI/NETA ATS | Standard for Acceptance Testing Specifications for Electrical Power Equipment and Systems |
+| 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) |
+| ASCE 7 | Minimum Design Loads and Associated Criteria for Buildings and Other Structures (Chapter 13) |
+| IEEE C37.23 | Standard for Metal-Enclosed Bus |
# Submittals {toc}
## Action Submittals {toc}
−### The Contractor shall submit the following action submittals for review before fabrication:
+### The Contractor shall submit the following for review before any busway is released for manufacture:
−- Product data for each busway type, including ampere rating, voltage rating, conductor material, and listing
−- Short-circuit current rating (SCCR) and bracing certification for the busway and all fittings
−- Shop drawings showing the complete routing, fitting schedule, dimensions, and support locations
−- Plug-in unit schedule identifying each unit by ampere rating, device type, and pole configuration
−- Coordination drawings reconciling busway routing with structure, piping, and ductwork
−- Manufacturer's installation instructions, including joint torque values and re-torque schedule
−- Seismic anchorage and bracing calculations where required by the seismic design category
+- shop drawings for each run giving the routing in plan and elevation, every straight length and fitting by catalog designation and length, the joint locations, the hanger locations and type, the expansion fitting locations, the fire-rated penetration locations, and the flanged end or tap box at each termination
+- product data for the busway series giving the continuous current rating, the short-circuit current rating and the duration on which it is established, the conductor material and plating, the housing construction and enclosure type, the neutral and ground path furnished, and the published resistance, reactance, and voltage drop per 100 ft at rated current
+- the dimensions and weight of every straight length and fitting, and the weight per foot of the run for the structural engineer's review of the supports
+- the flange drilling and bus stab arrangement at every termination, coordinated with the equipment manufacturer
+- the seismic restraint arrangement of the supports, where the datasheet requires restraint
+- the manufacturer's installation instructions, including the joint torque values and the hanger spacing for each orientation
```datasheet
−label: Action Submittals Required
+label: Action Submittals
type: checkbox
options:
− - Product data (rating, voltage, material, listing)
− - SCCR and bracing certification
− - Shop drawings (routing, fittings, supports)
− - Plug-in unit schedule
− - Coordination drawings
− - Installation instructions with torque values
− - Seismic anchorage and bracing calculations
+ - "Shop drawings"
+ - "Product data with published impedance and voltage drop"
+ - "Dimensions and weights"
+ - "Termination flange drilling and stab arrangement"
+ - "Seismic restraint arrangement"
+ - "Installation instructions with torque values and hanger spacing"
default:
− - Product data (rating, voltage, material, listing)
− - SCCR and bracing certification
− - Shop drawings (routing, fittings, supports)
− - Plug-in unit schedule
− - Installation instructions with torque values
+ - "Shop drawings"
+ - "Product data with published impedance and voltage drop"
+ - "Dimensions and weights"
+ - "Termination flange drilling and stab arrangement"
+ - "Installation instructions with torque values and hanger spacing"
```
−### Shop drawings shall be coordinated against [[drawing: busway riser and plan routing]] before fabrication so that field-measured lengths and fitting locations are confirmed.
+### The Contractor shall field-measure the route of each run and shall confirm the straight length and fitting schedule against the measured dimensions before the shop drawings are submitted.
−## Closeout Submittals {toc}
+### Busway is cut to length at the factory and a run is ordered as a schedule of lengths and fittings, so a dimension taken from the drawings rather than the building produces a run that does not close, and the correction is a special-length section on the manufacturer's lead time; this is why the field measurement precedes the submittal rather than the delivery. {note}
−### The Contractor shall submit the following closeout submittals before final acceptance:
+### A run shall not be released for manufacture until the action submittals covering it have been reviewed and returned.
−- Record drawings showing as-installed routing, fitting locations, and plug-in unit positions
−- Field test reports for insulation resistance and joint torque verification
−- Manufacturer's operation and maintenance manuals
−- Re-torque verification record after the first thermal cycle
−- Warranty documentation
+## 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 manufacturer's published derating factors applied for ambient temperature, altitude, and mounting orientation, where any of the three departs from the rating basis of the listing
+- the manufacturer's published maximum straight run length between expansion fittings for the conductor material furnished
+
```datasheet
−label: Closeout Submittals Required
+label: Informational Submittals
type: checkbox
options:
− - Record drawings (as-installed)
− - Insulation resistance test reports
− - Joint torque verification reports
− - Operation and maintenance manuals
− - Re-torque verification after first thermal cycle
− - Warranty documentation
+ - "Manufacturer's qualification statement"
+ - "Field testing firm and technician qualifications"
+ - "Ambient, altitude, and orientation derating factors"
+ - "Maximum run length between expansion fittings"
default:
− - Record drawings (as-installed)
− - Insulation resistance test reports
− - Joint torque verification reports
− - Operation and maintenance manuals
− - Re-torque verification after first thermal cycle
− - Warranty documentation
+ - "Manufacturer's qualification statement"
+ - "Field testing firm and technician qualifications"
+ - "Maximum run length between expansion fittings"
```
−## Informational Submittals {toc}
+## Closeout Submittals {toc}
−### The Contractor shall submit the following informational submittals:
+### The Contractor shall submit the following before any run is accepted:
−- Manufacturer's certification of compliance with UL 857 and NEMA BU 1
−- Short-circuit study correlating available fault current with the specified SCCR
−- Qualification statements for the installing personnel
−- Field quality-control test plan
+- record drawings reflecting the as-installed routing, every joint, hanger, expansion fitting, and penetration location, and the position of every plug-in opening on a plug-in run
+- the certified factory production test report for the lengths and fittings furnished
+- the field acceptance test report for each run, giving every measured value, the acceptance criterion applied, and the tester's determination
+- the joint torque record giving the value applied at every joint, or the record of torque-indicating bolt heads sheared, by joint location
+- the infrared thermographic inspection report, where the datasheet requires an inspection
+- operation and maintenance data covering the busway series, the joint inspection and re-torque interval of NEMA BU 1.1, and the procedure for adding a length or a fitting to the run
+- the warranty certificate identifying each run by designation and the warranty commencement date
+- a signed receipt from the Owner for the spare parts delivered
```datasheet
−label: Informational Submittals Required
+label: Closeout Submittals
type: checkbox
options:
− - Certification of compliance (UL 857, NEMA BU 1)
− - Short-circuit study correlation
− - Installer qualification statements
− - Field quality-control test plan
+ - "Record drawings"
+ - "Certified factory production test report"
+ - "Field acceptance test reports"
+ - "Joint torque record"
+ - "Infrared thermographic inspection report"
+ - "Operation and maintenance data"
+ - "Warranty certificate"
+ - "Spare parts receipt"
default:
− - Certification of compliance (UL 857, NEMA BU 1)
− - Short-circuit study correlation
− - Field quality-control test plan
+ - "Record drawings"
+ - "Certified factory production test report"
+ - "Field acceptance test reports"
+ - "Joint torque record"
+ - "Operation and maintenance data"
+ - "Warranty certificate"
+ - "Spare parts receipt"
```
# Quality Assurance {toc}
−## Busway and all associated fittings shall be products of a single manufacturer and a single product series, so that joint geometry, bracing, and plug-in interfaces are mutually compatible.
+## Manufacturer Qualifications {toc}
−## Plug-in units are proprietary to each manufacturer's busway series and are not interchangeable between brands or product lines; specifying an "equal" without identifying the series produces field incompatibility. {note}
+### The busway shall be produced by a manufacturer that has held a UL 857 listing for busway of the construction furnished for not less than the period indicated in the datasheet.
−## The busway and its fittings shall be listed and labeled by a Nationally Recognized Testing Laboratory under UL 857.
+```datasheet
+label: Minimum Manufacturer Listing History
+type: range
+unit: years
+options:
+ min: 0
+ max: 20
+ setpoints: [0, 3, 5, 10, 20]
+default: 5
+```
−## Each straight section, elbow, tee, and end closure shall carry the same listing as the run it serves; an outdoor run requires every fitting to share the outdoor listing, not only the straight sections.
+### The manufacturer shall state in the qualification statement the period, measured from the date of manufacture, for which straight lengths, fittings, joint hardware, and plug-in units compatible with the busway series furnished will remain available.
−## Outdoor-rated runs are a common failure point because elbows, tees, and end closures are sometimes left at an indoor rating; verify that the weatherproof listing covers the entire assembly. {note}
+### A busway series is extended with lengths and fittings that mate with its own joint and its own plug-in opening, and no other maker's product mates with either, so the Owner who adds a load or extends a run ten years on is buying from the original manufacturer or replacing the run; the availability period is what makes that purchase possible. {note}
−## The installing personnel shall be trained by the busway manufacturer or its authorized representative in joint assembly and torque verification for the specified product series.
+## Source Limitations {toc}
−## Manufacturer qualification: the manufacturer shall have produced UL 857-listed busway of the specified type and rating for not less than five years.
+### The straight lengths, the fittings, the joint hardware, the hangers, the end closures, and the expansion and fire-rated penetration fittings of a run shall be furnished by the busway manufacturer as one product series under one UL 857 listing.
−# Environmental and Service Conditions {toc}
+### Every run on the project shall be of one manufacturer's busway series, so that the spare joint hardware and the plug-in units interchange across runs.
−## Busway ratings are established at a defined ambient temperature; the specified rating must be verified against the actual installed environment, because high ambient temperature derates current-carrying capacity.
+### No length or fitting shall be field-fabricated, field-cut, or field-drilled, and no joint shall be made with hardware other than the hardware furnished for the joint under the listing.
+### The plug-in units that mount on a plug-in run shall be of the same manufacturer and listed for the busway series furnished, and shall comply with [[sync/feeder-busway-plug-in-units]].
+
+## Field Testing Firm {toc}
+
+### Field acceptance testing shall be performed by the firm indicated in the datasheet.
+
```datasheet
−label: Installation Environment
−type: select
+label: Field Acceptance Testing Firm
+type: radio
options:
− - Indoor, dry, ventilated
− - Indoor, high-ambient (>40 °C)
− - Outdoor, weatherproof (NEMA 3R)
− - Corrosive or washdown area
−default: Indoor, dry, ventilated
+ - "Independent testing firm accredited to ANSI/NETA ATS"
+ - "Manufacturer's field service organization"
+ - "Installing contractor's own technicians"
```
−## Standard busway is rated for operation in a maximum ambient air temperature of 40 °C unless a higher-ambient rating is specified.
+### The technicians who perform field acceptance testing shall hold a current certification for low-voltage equipment testing from NETA or from the busway manufacturer, and shall have tested busway of the construction furnished.
+### An independent firm has no stake in whether the run passes and reports against a published acceptance standard; the manufacturer's organization knows the joint and its torque indication 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 run would satisfy the Owner's insurer and the Authority Having Jurisdiction. {note}
+
+# Environmental and Service Conditions {toc}
+
+## Ambient Temperature {toc}
+
+### The busway shall carry its continuous current rating at the design ambient temperature of every space it passes through.
+
+### The design ambient temperature for an indoor run shall be as indicated in the datasheet.
+
```datasheet
−label: Maximum Ambient Air Temperature
+label: Indoor Design Ambient Temperature
type: range
unit: °C
−min: 30
−max: 60
−step: 5
+options:
+ min: 25
+ max: 55
+ setpoints: [25, 30, 40, 50, 55]
default: 40
```
−## Where busway is routed through boiler rooms, rooftop runs in direct sun, or other elevated-ambient locations, the ampacity shall be derated or a high-ambient-rated product specified.
+### UL 857 establishes the continuous current rating at a 40 °C ambient, so a 40 °C design ambient is the condition at which the nameplate rating applies without correction; a higher value covers a riser shaft, a mechanical room, or a ceiling space above a process that runs hotter than 40 °C at design load, at the cost of a larger busway for the same load. {note}
−## Indoor busway shall be installed only in dry, ventilated locations free from corrosive vapors, conductive dust, and dripping liquids unless a higher enclosure rating is specified.
+### A run 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 informational submittals.
−## Outdoor and wet-location busway shall use a weatherproof enclosure listed for the location, with drain provisions and gasketed joints.
+### Where a run passes through a space whose ambient exceeds the design ambient, the derating for that space shall apply to the whole run, because the current the run carries is the same at every point along it.
+## Altitude {toc}
+
+### The busway shall be derated for [[parameter: altitude]] in accordance with the manufacturer's published correction factors where the altitude exceeds the 2000 m rating basis of the listing.
+
+### Air thins with altitude, which reduces the convective cooling that sets the continuous current rating of the bus bars and the dielectric strength of the clearances inside the housing, so a run 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.
+
+## Seismic Restraint {toc}
+
+### The seismic restraint required for the hangers and supports of each run shall be as indicated in the datasheet.
+
```datasheet
−label: Enclosure Type
+label: Seismic Restraint Requirement
type: select
+derived: "[[parameter: seismic-design-category]] and the component importance factor assigned to the busway under ASCE 7 Chapter 13"
options:
− - Ventilated indoor feeder
− - Ventilated indoor plug-in
− - Totally enclosed (non-ventilated)
− - Weatherproof NEMA 3R
−default: Ventilated indoor feeder
+ - "Not required"
+ - "Restraint of the hangers and supports per ASCE 7 Chapter 13"
+default: derived
```
−## Select the enclosure type to match the installed environment; an indoor feeder housing relocated outdoors will admit water at the joints and fail. {note}
+### Whether the run must be restrained follows from the seismic design category and from the importance factor the code assigns to the loads it serves, so the field carries the consequence of those inputs rather than a preference; a run serving egress lighting, a fire pump, or another load a Risk Category IV facility depends on carries the higher importance factor and is restrained in a category where an ordinary run is not. {note}
−# Ratings and Electrical Characteristics {toc}
+### Where seismic restraint is required, it shall be designed and installed in accordance with the seismic provisions of [[parameter: adopted-building-code]], ASCE 7 Chapter 13, and [[sync/vibration-isolation-and-seismic-restraint]], and the restraint shall attach to the hanger or the busway only at the points the busway manufacturer designates for it.
−## Voltage and System Configuration {toc}
+### Where seismic restraint is required, the restraint shall not prevent the thermal movement the expansion fittings are furnished to absorb, and a restrained run shall be braced on one side only of each expansion fitting.
−### The busway voltage rating shall equal or exceed the nominal system voltage at the point of installation.
+# Electrical Ratings {toc}
−### Standard low-voltage busway is rated 600 V or less; systems above 600 V require medium-voltage bus outside this scope. {note}
+## Busway Type {toc}
−### The number of poles and the neutral configuration shall match the system and the load characteristics served.
+### The busway type of each run, and of each section of a run where the type changes along it, shall be as indicated in the datasheet.
```datasheet
−label: System Voltage
−type: select
+label: Busway Type
+type: radio
+drawing_ref: "the one-line diagram"
options:
− - 208Y/120 V, 3Φ, 4W
− - 480Y/277 V, 3Φ, 4W
− - 480 V, 3Φ, 3W
− - 240 V, 3Φ, 3W
− - 600 V, 3Φ, 3W
−default: 480Y/277 V, 3Φ, 4W
+ - "Feeder busway"
+ - "Plug-in busway"
+default: deferred
```
+### Feeder busway has no openings along its length and is the construction a riser from a switchboard to a floor, a transformer-to-switchboard connection, or a run from one piece of equipment to another is built with; plug-in busway carries openings at intervals that accept the plug-in units a load taps from, and it costs more per foot for the openings and their covers. A run whose loads sit at its far end is feeder busway for the whole length; a run whose loads are spread along it is feeder busway from the source to the first load and plug-in busway from there on. {note}
+
+### Where a run changes from feeder to plug-in construction, the change shall be made at a joint with a transition fitting of the same series, and the location of the change shall be as indicated on [[drawing: the busway routing plans and riser diagram]].
+
+## Service Entrance Use {toc}
+
+### Whether a run carries service-entrance conductors shall be as indicated in the datasheet.
+
```datasheet
−label: Pole and Neutral Configuration
−type: select
+label: Service Entrance Use
+type: radio
+drawing_ref: "the one-line diagram"
options:
− - 3-pole, 3-wire (no neutral)
− - 4-pole, 100% neutral
− - 4-pole, 200% (double) neutral
−default: 4-pole, 100% neutral
+ - "Not service entrance busway"
+ - "Service entrance busway"
+default: deferred
```
−### Where the served load is harmonic-rich, such as data center, UPS, or VFD-heavy installations, a 200% (double) neutral shall be specified to carry triplen-harmonic currents.
+### Where a run carries service-entrance conductors, the busway shall be listed and marked as suitable for use as service-entrance equipment, shall comply with NFPA 70 Article 230 for the portion ahead of the service disconnecting means, and shall carry no plug-in opening ahead of the service disconnecting means.
−### Specifying a standard 100% neutral for harmonic-heavy loads is a common error; third-harmonic currents add arithmetically in the neutral and can overload a standard neutral bar. {note}
+### Where a run carries service-entrance conductors, the serving utility's acceptance of the busway as the service-entrance wiring method shall be confirmed in writing before the run is released for manufacture, and the service point and the service disconnect shall be as [[sync/electrical-service-entrance]] requires.
−## Ampere Rating {toc}
+## System Voltage and Frequency {toc}
−### The continuous ampere rating shall be selected from the manufacturer's standard catalog ratings and shall equal or exceed the calculated feeder load.
+### The system voltage and configuration shall be as indicated in the datasheet.
−### Copper bus offers higher conductivity in a smaller cross-section but is heavier and more costly; aluminum bus is lighter and lower cost but requires a larger cross-section and antioxidant compound at terminations. {note}
+```datasheet
+label: System Voltage
+type: select
+drawing_ref: "the one-line diagram"
+options:
+ - "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"
+ - "600Y/347 V 3Φ 4-wire"
+ - "600 V 3Φ 3-wire delta"
+default: deferred
+```
−### The conductor material shall be specified, because it governs cross-section, weight, support spacing, and termination preparation.
+### The number of phases and the number of wires follow from the system voltage selected, and the number of bus bars in the housing and the presence of a neutral bar follow from them in turn. {note}
+### The busway voltage rating shall equal or exceed the system voltage, and where the run is fed from a transformer secondary the Contractor shall confirm the rating against the secondary configuration of the transformer before the run is released for manufacture.
+
+### Where the system is a high-leg delta, the high leg shall be connected to the B phase bar and shall be identified at every plug-in opening, tap box, and flanged end in accordance with NFPA 70 110.15.
+
+### The system frequency shall be as indicated in the datasheet.
+
```datasheet
−label: Continuous Ampere Rating
−type: select
−unit: A
+label: System Frequency
+type: radio
options:
− - 225
− - 400
− - 600
− - 800
− - 1000
− - 1200
− - 1350
− - 1600
− - 2000
− - 2500
− - 3000
− - 4000
− - 5000
−default: 1600
+ - "60 Hz"
+ - "50 Hz"
+default: "60 Hz"
```
+## Continuous Current Rating {toc}
+
+### The continuous current rating of each run shall be as indicated in the datasheet.
+
```datasheet
−label: Conductor Material
−type: select
+label: Continuous Current Rating
+type: range
+unit: A
+drawing_ref: "the one-line diagram"
options:
− - Copper
− - Aluminum
−default: Copper
+ min: 100
+ max: 6000
+ setpoints: [100, 225, 400, 600, 800, 1000, 1200, 1350, 1600, 2000, 2500, 3000, 3200, 4000, 5000, 6000]
+default: deferred
```
−### Aluminum busway terminations shall be prepared with the manufacturer's specified antioxidant compound and termination hardware; aluminum is not a plug-and-play substitute for copper.
+### The rating of a run is fixed by the calculated load of NFPA 70 Article 220, the overcurrent device that protects it under NFPA 70 368.17, and the spare capacity the project wants to leave, and it is stated on the one-line diagram with that device; a run cannot be uprated after manufacture without replacing every length and fitting that carries the current, which is why the rating is chosen against the ultimate load rather than the first-day load. {note}
−### Treating aluminum terminations as identical to copper leads to high-resistance joints and overheating; the oxide film must be abraded and inhibited at every connection.
+### The busway shall carry its continuous current rating in every mounting orientation in which it is installed, or the manufacturer shall state the derating for each orientation in the informational submittals, and the rating after derating shall be not less than the rating the datasheet indicates.
+### Where a run reduces in rating along its length, the reduced section shall be protected at its rating by an overcurrent device at the point of reduction, unless the reduced section satisfies every condition under which NFPA 70 368.17(B) permits it to be protected by the device ahead of the full-rated section.
+
+### The manufacturer shall publish the resistance, the reactance, and the line-to-line voltage drop per 100 ft of run at rated current and at a balanced load of 0.8 power factor, in the product data.
+
## Short-Circuit Current Rating {toc}
−### The short-circuit current rating (SCCR) of the busway and its bracing shall equal or exceed the available fault current at every point of the run.
+### The available fault current at the source end of each run shall be as indicated on [[drawing: the one-line diagram]].
+### The short-circuit current rating of each run, including every fitting, joint, and plug-in opening in it, shall equal or exceed the available fault current at its source end as established under [[sync/short-circuit-study]], and shall be as indicated in the datasheet.
+
```datasheet
−label: Short-Circuit Current Rating (SCCR)
−type: select
+label: Short-Circuit Current Rating
+type: range
unit: kA
+drawing_ref: "the one-line diagram"
options:
− - 22
− - 42
− - 65
− - 85
−default: 65
+ min: 10
+ max: 200
+ setpoints: [10, 14, 22, 25, 35, 42, 50, 65, 85, 100, 125, 150, 200]
+default: deferred
```
−### A system short-circuit study shall be obtained before the SCCR is selected, so that the busway bracing is coordinated with the actual available fault current.
+### The short-circuit current rating of a busway is the symmetrical RMS current its bus bars, supports, and joints carried without damage in the UL 857 short-circuit test, and the rating of a run is the lowest rating among its lengths and fittings, so one fitting of a lower rating sets the rating of the whole run. {note}
−### Specifying an SCCR below the available fault current is among the most common and most dangerous errors in busway design; an under-braced bus can deform or rupture during a fault. {note}
+### Where the one-line diagram relies on a current-limiting device ahead of the run to reduce the fault current the busway sees, the reduced rating shall be applied only where the manufacturer has listed the busway for use with that device class and rating as a tested combination, and the combination shall be identified in the action submittals.
−### The SCCR shall be expressed in symmetrical RMS amperes and shall be referenced to the fault-clearing time of the upstream overcurrent device.
+### The duration on which the short-circuit current rating is established shall be as indicated in the datasheet.
```datasheet
−label: Bracing Basis (Fault-Clearing Time)
−type: select
+label: Short-Circuit Rating Duration
+type: radio
options:
− - 3-cycle
− - 6-cycle
−default: 3-cycle
+ - "3-cycle short-circuit rating"
+ - "30-cycle short-time withstand rating"
+default: "3-cycle short-circuit rating"
```
−### Where current-limiting fuses or breakers reduce the let-through current, the reduced rating may be applied only when the protective device and its coordination are documented. {note}
+### UL 857 establishes the short-circuit rating over 3 cycles, which is the time a molded-case device takes to clear, and that is the basis every listed busway is rated on; a 30-cycle short-time rating braces the bus bars and the supports to carry the fault for a half second, which is what a run needs where the device protecting it has its instantaneous element set above the arcing current or defeated so that a device downstream clears first, as a selectively coordinated system often requires at a main. The 30-cycle rating is bought with heavier supports, and not every busway series offers it at every ampere rating. {note}
−### The available fault current at the busway origin shall be confirmed against [[drawing: one-line diagram fault values]] before the SCCR is finalized.
+### Where a 30-cycle short-time withstand rating is selected, the rating shall be established by test for the duration and shall be marked on the busway, and the device protecting the run shall carry a short-time rating not less than the busway rating for 30 cycles.
−# Bus Bars {toc}
+## Neutral Bar {toc}
−## Bus bars shall be of the specified conductor material, of rectangular cross-section, and sized for the continuous rating at the rated temperature rise.
+### The neutral bar furnished in each run shall be as indicated in the datasheet.
−## Bus bars shall be plated at all joint and plug-in contact surfaces with tin or silver to ensure a stable, low-resistance contact over the life of the system.
+```datasheet
+label: Neutral Bar
+type: select
+derived: "the system voltage configuration and the share of nonlinear load served from the busway"
+options:
+ - "No neutral bar"
+ - "Neutral bar rated 100% of the phase bars"
+ - "Neutral bar rated 200% of the phase bars"
+default: derived
+```
−## Joint plating prevents the contact resistance from rising as the bare base metal oxidizes; an unplated joint runs hot and loosens over time. {note}
+### A three-wire system has no neutral to carry; a four-wire system with ordinary single-phase load carries a neutral rated with the phase bars; and a four-wire system whose load is predominantly single-phase nonlinear equipment, such as switch-mode power supplies, LED drivers, and single-phase drives, carries the triplen harmonic currents that add in the neutral rather than cancel, which is the condition under which the neutral is rated above the phase bars. A 200% neutral is furnished as a double-width bar or a second neutral bar in the same housing, and it changes the joint, the plug-in opening, and the flanged end, so it is chosen when the run is ordered rather than added later. {note}
−## Bus bars shall be supported and insulated within the housing so that they withstand the mechanical forces of the rated short-circuit current without permanent deformation.
+### Where a neutral bar is furnished, it shall be insulated from the housing, shall be of the same conductor material and plating as the phase bars, and shall extend the full length of the run including every fitting and every plug-in opening.
−## Bus bar insulation shall be a flame-retardant material with a temperature rating not less than the maximum bus operating temperature.
+### Where a neutral bar is furnished, the neutral shall be bonded to the ground path only at the service equipment or at the separately derived system source, as [[sync/grounding-and-bonding]] requires, and nowhere along the run.
+## Ground Path {toc}
+
+### The equipment grounding path furnished in each run shall be as indicated in the datasheet.
+
```datasheet
−label: Joint Contact Plating
+label: Ground Path
type: select
options:
− - Tin-plated
− - Silver-plated
−default: Tin-plated
+ - "Housing as the equipment grounding conductor"
+ - "Housing as the equipment grounding conductor and an isolated ground bar"
+ - "Internal ground bar"
+ - "Internal ground bar and an isolated ground bar"
```
+### A housing listed as the equipment grounding conductor carries the fault current in the housing itself and in the joint hardware that bonds one length to the next, which costs nothing beyond the listing and depends on every joint staying tight for the life of the run; an internal ground bar is a bus bar inside the housing, joined at every joint like the phase bars, which gives the fault current a path whose resistance the joint torque controls as it controls the phase bars and gives every plug-in unit a ground stab rather than a housing clamp; an isolated ground bar is a second ground bar insulated from the housing and run back to the isolated ground terminal at the source, which keeps the reference ground of electronic equipment apart from the housing that carries circulating and fault current. Which path a project wants depends on the loads tapped from the run and on the Owner's practice, so the field asserts no default. {note}
+
+### Where the housing serves as the equipment grounding conductor, the busway shall be listed and marked for that use, and every joint, fitting, and end closure shall maintain the ground path at the rating of the listing.
+
+### Where an internal ground bar is furnished, its rating as a share of the phase bar rating shall be as indicated in the datasheet.
+
```datasheet
−label: Bus Bar Temperature Rise (over 40 °C ambient)
+label: Internal Ground Bar Rating
type: range
−unit: °C
−min: 55
−max: 65
−step: 5
−default: 55
+unit: '%'
+options:
+ min: 50
+ max: 100
+ setpoints: [50, 100]
```
−# Housing {toc}
+### A ground bar rated at half the phase bars satisfies the equipment grounding conductor sizing of NFPA 70 250.122 for every busway rating and is the bar most series are built with; a full-rated ground bar is furnished where the Owner's practice calls for it or where the ground path is to carry the return of a high-resistance-grounded or an isolated system, at the cost of the bar. {note}
−## The housing shall be a totally enclosing metallic enclosure of steel or aluminum that provides mechanical protection and serves as the equipment grounding path where so listed.
+### Where an isolated ground bar is furnished, it shall be insulated from the housing and from the equipment ground path along the full length of the run, shall be bonded to the equipment ground only at the source as NFPA 70 250.146(D) permits, and shall be identified as the isolated ground at every plug-in opening and tap box.
−## A ventilated housing permits convective cooling and supports a higher continuous rating; a non-ventilated housing is required where airborne contaminants or wet locations are present. {note}
+### Grounding and bonding of the run and of the equipment it connects shall comply with [[sync/grounding-and-bonding]] and NFPA 70 368.60.
−## The housing finish shall be a corrosion-resistant coating suitable for the installed environment.
+# Bus Bars and Joints {toc}
−## Plug-in housing shall provide plug-in openings on one or both sides at the specified interval, each with a protective cover that maintains the enclosure rating when no unit is installed.
+## Conductor Material {toc}
+### The bus bar material shall be as indicated in the datasheet.
+
```datasheet
−label: Housing Material
−type: select
+label: Conductor Material
+type: radio
options:
− - Steel
− - Aluminum
−default: Steel
+ - "Copper"
+ - "Aluminum"
```
+### Copper bus carries more current per unit cross-section, which gives a smaller housing for the same rating, has the lower contact resistance at a bolted joint, and costs more; aluminum bus is lighter and less expensive for the same rating, which matters on a long overhead run where the hanger load and the material cost scale with the length, and its joints depend on the plating and on the joint hardware to hold their resistance through thermal cycling. Copper is chosen where the riser shaft or the ceiling space is tight, where the run is to be field-extended often, or where the environment attacks aluminum; aluminum is chosen where the run is long, the space is open, and the weight carried by the structure matters. Neither is distinctly the norm across projects, so the field asserts no default. {note}
+
+### Where copper is selected, the bus bars shall be copper bus bar conforming to ASTM B187 with a conductivity of not less than 98% IACS.
+
+### Where aluminum is selected, the bus bars shall be an aluminum alloy bus conductor conforming to ASTM B317 with a conductivity of not less than 55% IACS, and shall be plated over the full length of every bar.
+
+### Where aluminum is selected, every joint between an aluminum bar and a copper bar, stab, or lug, including the stab of a plug-in unit and the flange at a termination, shall be made through a plated contact surface listed for the combination.
+
+## Bus Bar Plating {toc}
+
+### The bus bar plating shall be as indicated in the datasheet.
+
```datasheet
−label: Plug-In Opening Interval
−type: select
−unit: in
+label: Bus Bar Plating
+type: radio
options:
− - 12
− - 18
− - 24
−default: 24
+ - "Tin-plated"
+ - "Silver-plated"
+default: manufacturer
```
+### The manufacturer shall state the plating in the product data.
+
+### Tin plating resists the sulfur compounds that blacken silver and raise its contact resistance, and holds its resistance where the atmosphere carries hydrogen sulfide, as in a wastewater facility; silver plating has the lower contact resistance in a clean atmosphere. Each busway series is built with one plating as its standard, and that standard serves every ordinary indoor run, which is why the field starts in the manufacturer's standard state. {note}
+
+### Plating shall be continuous over every joint contact surface, every plug-in opening stab surface, and every flanged end and tap box connection, and copper bars shall be plated over the full length or at every contact surface, as the listing requires.
+
+## Bus Bar Insulation and Temperature Rise {toc}
+
+### The bus bars shall be insulated over their full length with a flame-retardant insulation rated for the system voltage and for the maximum bus temperature at rated current, applied as the listing requires, and the bars shall be supported within the housing so that they withstand the forces of the short-circuit current rating without permanent deformation.
+
+### The temperature rise of the bus bars at the continuous current rating shall not exceed the rise UL 857 permits for the plating furnished, measured over a 40 °C ambient, and the manufacturer shall state the rise basis in the product data.
+
+### UL 857 limits the rise at a plated joint to 55 °C over a 40 °C ambient, which puts the bar at 95 °C at rated current in a 40 °C space, and the insulation, the supports, and the joint hardware are chosen for that temperature; an unplated joint is held to a lower rise, which is why every listed busway plates its joints. {note}
+
+## Joints {toc}
+
+### Each joint between two lengths or fittings shall be a bolted joint furnished by the manufacturer under the listing, shall carry the continuous current rating and the short-circuit current rating of the run, and shall be made with the hardware furnished for it.
+
+### The torque indication of the joint bolts shall be as indicated in the datasheet.
+
```datasheet
−label: Plug-In Opening Sides
−type: select
+label: Joint Bolt Torque Indication
+type: radio
options:
− - One side
− - Both sides
−default: One side
+ - "Torque-indicating bolts with a break-off or double head"
+ - "Plain bolts torqued with a calibrated tool"
+default: "Torque-indicating bolts with a break-off or double head"
```
−# Grounding {toc}
+### A torque-indicating bolt shears its outer head at the listed torque, so that a glance at the joint shows whether it was made up correctly and the installer needs no torque tool at the joint, and it is the hardware the single-bolt joint of every current busway series is built with; a plain bolt is torqued with a calibrated tool and leaves no visible record, so the torque record is the only evidence the joint was made up, and it is the hardware an older series or a multi-bolt joint is built with. {note}
−## The busway shall provide an equipment grounding path of the rated capacity, either through the housing itself where listed or through an internal ground bus bar.
+### Each joint shall be removable from one side of the run without disturbing the adjacent lengths, so that a length or a fitting can be removed and replaced in a completed run.
−## Where the served load is sensitive electronic equipment, a separate insulated (isolated) ground bus bar shall be provided in addition to the housing ground.
+### Each joint shall be accessible after installation for torque verification, for infrared inspection under load, and for inspection of the joint cover, and no joint shall be located within a wall, a floor, or a fire-rated penetration fitting.
−## An isolated ground bus keeps the clean ground reference independent of the housing, which carries circulating and fault currents; this matters for data and instrumentation loads. {note}
+### Each joint shall be covered by a joint cover that maintains the enclosure type of the run and that is removable without tools other than those the manufacturer furnishes.
−## Grounding and bonding of the busway shall comply with [[sync/grounding-and-bonding]] and NFPA 70 Article 250.
+# Housing {toc}
+## Housing Construction {toc}
+
+### The housing construction shall be as indicated in the datasheet.
+
```datasheet
−label: Grounding Arrangement
−type: select
+label: Housing Construction
+type: radio
options:
− - Housing as equipment ground
− - Internal ground bus bar
− - Internal ground bus plus isolated ground bus
−default: Internal ground bus bar
+ - "Non-ventilated"
+ - "Ventilated"
+default: "Non-ventilated"
```
−# Fittings {toc}
+### A non-ventilated housing encloses the insulated bars in close contact with the housing walls, so that the housing conducts the heat out and the bars sit close together, which gives the low reactance and the low voltage drop the construction is sold on and keeps dust, sprinkler water, and a dropped tool out of the bars; it is the construction every current busway series is built as, which is why it is the default. A ventilated housing holds bare or sleeved bars apart on insulators with louvers in the housing for convective cooling, which was the construction before the non-ventilated designs reached the higher ratings, and it is derated when mounted flat, admits whatever the air carries, and is the construction an existing run is extended with where the existing series is ventilated. {note}
−## Elbows, tees, offsets, and transformer or switchboard taps shall be factory-fabricated fittings of the same series, rating, and listing as the straight busway.
+### Busway installed through a floor, outdoors, in a space used for environmental air, behind an access panel, or in a wet or damp location shall be of non-ventilated construction, whatever the datasheet selects, as NFPA 70 368.10(C)(2), 368.12, and 300.22(C) require for those locations.
−## Field-fabricated fittings are prohibited; the bracing and joint geometry of a busway run are validated only as a manufactured assembly.
+### The housing shall be rigid enough that the run spans the manufacturer's maximum hanger spacing in every orientation shown on the shop drawings without a deflection that bears on a joint, and the manufacturer shall state the spacing for each orientation in the installation instructions.
−## End closures (dead ends) shall be installed at every unused open end of the busway to maintain the enclosure and isolate the live bus.
+## Enclosure Type {toc}
−## Phase transposition or center-tapped sections shall be provided on long plug-in runs where load is consistently tapped from one side, to equalize phase loading.
+### The enclosure type shall be as indicated in the datasheet.
```datasheet
−label: Phase Transposition Section
+label: Enclosure Type
type: select
options:
− - Not required (balanced tapping)
− - Required (one-sided plug-in run)
−default: Not required (balanced tapping)
+ - "Indoor, Type 1"
+ - "Indoor, sprinkler-resistant"
+ - "Outdoor, Type 3R"
+default: "Indoor, Type 1"
```
−## Without transposition on a long one-sided plug-in run, the phase nearest the loads carries more current than the others, creating measurable phase unbalance and voltage drop differences. {note}
+### Busway runs indoors on most projects, in a riser shaft, an electrical room, or a ceiling space, which is why Type 1 is the default; a sprinkler-resistant housing is the Type 1 housing with gasketed joint covers and plug-in opening covers and with drain provisions, built for a run under sprinkler heads whose discharge would otherwise enter the housing at the joints; a Type 3R housing sheds rain and is built with drain openings, weather-sealed joints, and outdoor-listed fittings for a run between buildings, on a roof, or along an exterior wall. {note}
−# Expansion Fittings {toc}
+### The enclosure type shall be designated in accordance with NEMA 250, and the type shall be marked on the housing.
−## Busway expands and contracts with temperature and with building movement; without an accommodation the joints carry the resulting stress and eventually loosen or overheat. {note}
+### A run installed outdoors, in a wet location, or where it is exposed to rain or to water from washing shall have a Type 3R enclosure.
−## Expansion fittings shall be provided on long straight runs at the manufacturer's maximum spacing for the expected temperature differential.
+### Where a Type 3R enclosure is furnished, every straight length, fitting, joint cover, end closure, flanged end, and expansion fitting in the outdoor portion of the run shall carry the outdoor listing, and no plug-in opening shall be furnished in the outdoor portion unless the manufacturer lists the opening and its cover for the Type 3R enclosure.
−```datasheet
−label: Expansion Fitting Spacing (long straight runs)
−type: range
−unit: ft
−min: 50
−max: 100
−step: 25
−default: 75
−```
+### Where a run passes from indoors to outdoors, the transition shall be made with a wall flange or a weather seal the manufacturer furnishes for the busway series, and the indoor portion shall slope or drain so that water entering at the transition does not reach an indoor joint.
−## Expansion fittings shall be provided where a busway run crosses a building expansion joint, in accordance with NFPA 70 Section 300.7(B).
+### A run installed where the atmosphere carries salt, chemical vapor, or another corrosive agent, including a coastal site exposure, a wastewater facility, or a chemical process area, shall have a housing and hardware the manufacturer states in writing are suitable for that atmosphere, and a run shall not be installed where NFPA 70 368.12 prohibits busway.
+### An indoor run installed under sprinkler heads shall have a sprinkler-resistant enclosure unless the datasheet selects Type 3R for the run.
+
+## Housing Material and Finish {toc}
+
+### The housing material shall be as indicated in the datasheet.
+
```datasheet
−label: Expansion Fitting at Building Expansion Joint
−type: checkbox
+label: Housing Material
+type: radio
options:
− - Required where run crosses a building expansion joint
−default:
− - Required where run crosses a building expansion joint
+ - "Aluminum"
+ - "Steel"
+default: manufacturer
```
−## Omitting expansion fittings on long runs is a frequent defect that transfers thermal stress into the bolted joints; it is corrected only by re-engineering the run. {note}
+### The manufacturer shall state the housing material in the product data.
−# Plug-In Units {toc}
+### An aluminum housing weighs less per foot, which lowers the hanger load on a long run, and carries no magnetic hysteresis loss, so the housing runs cooler at high current; a steel housing is stiffer across a long hanger span and resists impact where the run is reached by a lift truck or a falling object. Each series is built with one as its standard, and a project orders the other only where the weight or the exposure calls for it. {note}
−## Plug-in units provide overcurrent-protected load tap-off at the busway plug-in openings and shall match the busway series and the branch-circuit requirements.
+### The finish of the housing shall be as indicated in the datasheet.
−## Each plug-in unit shall be furnished with a disconnect device, either a fusible switch or a molded-case circuit breaker, as specified for the served load.
−
```datasheet
−label: Plug-In Unit Disconnect Type
+label: Housing Finish
type: select
options:
− - Fusible switch
− - Molded-case circuit breaker
−default: Molded-case circuit breaker
+ - "ANSI 61 light gray paint"
+ - "ANSI 49 medium gray paint"
+ - "Unpainted aluminum"
+ - "Custom color matched to a sample furnished by the Owner"
+default: manufacturer
```
−## Fusible plug-in units shall use the specified fuse class and ampere rating; molded-case units shall be rated for the available fault current at the plug-in point.
+### The manufacturer shall state the finish in the product data.
+### ANSI 61 is the gray the other electrical equipment on a project most often matches; an unpainted aluminum housing is what some series ship as and serves a riser shaft or a ceiling space nobody sees; a custom color is chosen where the run is exposed in a finished space or where the Owner color-codes the system it serves. {note}
+
+### A painted housing shall carry a baked powder coat or enamel finish over a pretreatment, and a steel housing shall be galvanized or finished so that no bare steel is exposed inside or outside the housing.
+
+## Plug-In Openings {toc}
+
+### On a plug-in run, the spacing of the plug-in openings along each side of the housing shall be as indicated in the datasheet.
+
```datasheet
−label: Fusible Unit Fuse Class
−type: select
+label: Plug-In Opening Spacing
+type: range
+unit: in
options:
− - Class J
− - Class RK1
− - Class RK5
−default: Class J
+ min: 12
+ max: 36
+ setpoints: [12, 18, 24, 36]
```
−## Plug-in unit overcurrent protection shall be sized within the limits of NFPA 70 Article 368.17 and Article 240 for the busway ampacity and the branch circuit served.
+### Where a spacing is not selected in the datasheet, the manufacturer's standard spacing for the busway series shall be furnished and shall be stated in the product data.
+### A closer spacing lets a plug-in unit land nearer to the load it serves and costs more openings per foot; the spacing the series is built with is the spacing its straight lengths are cut to, and a different spacing changes the length schedule. {note}
+
+### The sides of the housing on which plug-in openings are furnished shall be as indicated in the datasheet.
+
```datasheet
−label: Plug-In Unit Ampere Rating
−type: select
−unit: A
+label: Plug-In Opening Sides
+type: radio
options:
− - 30
− - 60
− - 100
− - 200
− - 400
− - 600
− - 800
− - 1200
− - 1600
−default: 100
+ - "Both sides"
+ - "One side"
+default: "Both sides"
```
−## Oversizing the plug-in overcurrent device is a code violation; Article 368.17 limits the device rating relative to the busway, and the branch circuit must comply with Article 240. {note}
+### Openings on both sides are what a plug-in series is built with and let a unit be mounted from whichever side the load sits on; openings on one side are ordered where the run is mounted against a wall or a structure that blocks the other side and the Owner does not want covered openings it cannot use. {note}
−## Plug-in units shall include an interlock that prevents insertion or removal while the unit is in the ON position.
+### Each plug-in opening shall be closed by a cover that is hinged or captive, that is held closed by a spring or a latch, that maintains the enclosure type of the run with no unit installed, and that cannot be left open with no unit in place.
−## The on/off interlock protects personnel during energized insertion and removal; busway is frequently live when units are added, so this interlock is a core safety feature. {note}
+### Each plug-in opening shall present the phase, neutral, and ground stabs in the same sequence on both sides of the run, so that a plug-in unit mounted on either side connects its poles to the same phases.
−## The number of poles for each plug-in unit shall be specified to match the phase configuration of the load it serves.
+### Where a long plug-in run is loaded predominantly from one side and the one-line diagram indicates a phase transposition section, the section shall be a factory fitting of the same series, located as indicated on [[drawing: the busway routing plans and riser diagram]].
+# Fittings {toc}
+
+## Elbows, Tees, Offsets, and Reducers {toc}
+
+### Elbows, tees, crosses, offsets, and reducers shall be factory fittings of the same series, rating, enclosure type, and listing as the straight lengths they join, and shall be furnished in the configuration shown on the reviewed shop drawings.
+
+### A reducer shall change the rating of the run only at a point where the reduced section is protected as the Continuous Current Rating article requires.
+
+### Where the routing requires a fitting of a non-standard angle or length, the fitting shall be made by the manufacturer under the listing, and the field shall not alter a fitting to suit the routing.
+
+## Flanged Ends and Tap Boxes {toc}
+
+### Where a run terminates at a switchboard, a substation secondary section, a panelboard, a transformer, or other equipment with a busway flange, the busway end shall be a flanged end fitting furnished by the busway manufacturer, drilled to mate with the flange that equipment's manufacturer furnishes under the standard governing that equipment, and the busway manufacturer shall coordinate the flange drilling, the bus stab arrangement, the phase sequence, and the neutral and ground positions with the equipment manufacturer before either is released for manufacture.
+
+### The flange on the switchboard or substation side, the bus connection inside the equipment, and the barrier at the entry are furnished by the equipment manufacturer under that equipment's listing, as [[sync/low-voltage-switchboards]] and [[sync/secondary-unit-substations]] require, and the busway side is furnished under this standard; the drilling and the stab arrangement are coordinated between the two manufacturers because a mismatch found at installation is corrected by a new flanged end on the busway manufacturer's lead time. {note}
+
+### Where a run terminates at equipment without a busway flange, or where conductors join the run at a point along it, the connection shall be made through a cable tap box of the same series and rating, furnished with lugs listed for the conductor material and size indicated on the one-line diagram and rated for 75 °C conductors, and the conductors landed in it shall comply with [[sync/conductors-and-cables]].
+
+### A cable tap box shall carry the short-circuit current rating of the run, shall provide the bending space NFPA 70 312.6 requires for the conductors landed in it, and shall be arranged so that the lugs are reached without removing a bus barrier.
+
+### Where a run connects to the secondary of a transformer, the busway shall be furnished with the flexible connector or the expansion fitting the busway manufacturer requires at that connection, so that the transformer vibration and its thermal movement are not carried into the busway joints.
+
+## End Closures {toc}
+
+### Every open end of a run that does not terminate at equipment shall be closed with an end closure of the same series and enclosure type, as NFPA 70 368.58 requires, and no run shall be energized with an open end.
+
+### Where a run is to be extended in the future, the end closure at the extension end shall be removable, and the end shall be located as indicated on [[drawing: the busway routing plans and riser diagram]].
+
+## Expansion Fittings {toc}
+
+### An expansion fitting of the same series and rating shall be furnished in every straight run whose length exceeds the manufacturer's published maximum run length between expansion fittings for the conductor material furnished, at intervals not exceeding that length.
+
+### An expansion fitting shall be furnished where a run crosses a building expansion joint shown on [[drawing: the structural framing plans]], located at the joint, and the hangers on each side of the fitting shall allow the movement the fitting is furnished to absorb.
+
+### An expansion fitting shall be furnished in a vertical riser where the manufacturer's instructions require one for the riser height and the conductor material, and the fitting shall be located at the point in the riser the manufacturer designates.
+
+### The bus bars grow with temperature at a rate the conductor material sets, and the housing, which runs cooler, grows less, so a long run with no fitting to take up the difference carries the thermal stress into the joints and the hangers, where it loosens the joint hardware over the seasons; an aluminum bus grows about half again as much as a copper bus over the same temperature change, which is why the maximum run length is published per conductor material. {note}
+
+## Fire-Rated Penetration Fittings {toc}
+
+### Where a run passes through a fire-resistance-rated wall or floor, the opening around the run shall be closed by the method indicated in the datasheet, so that the rating of the assembly is restored as NFPA 70 300.21 and [[parameter: adopted-building-code]] require.
+
```datasheet
−label: Plug-In Unit Poles
−type: select
+label: Rated Penetration Method
+type: radio
options:
− - 2-pole
− - 3-pole
−default: 3-pole
+ - "Manufacturer's listed busway fire barrier fitting"
+ - "Through-penetration firestop system listed for the busway profile"
```
−## Plug-in unit locations shall be coordinated against [[drawing: plug-in unit plan locations]].
+### A busway fire barrier fitting is a factory section of the run, tested by the busway manufacturer as a through-penetration system for the busway profile, that carries the rating for the hourly assembly and installs with the run; a through-penetration firestop system is a listed combination of packing and sealing material installed around the run by the firestop trade under [[sync/firestopping]], chosen from the listings that cover a busway or bus duct penetrating item. The fitting puts the rating in the busway manufacturer's hands and on the busway schedule, and is what a riser through several rated floors is usually built with; the firestop system puts it in the firestop installer's hands with the rest of the building's penetrations, and is what a single wall penetration on a horizontal run is usually closed with. Either is listed for the assembly it is installed in, and which a project wants depends on how many rated assemblies the run crosses and on which trade the project holds responsible for the rated penetrations. {note}
−# Testing {toc}
+### Where a busway fire barrier fitting is selected, it shall be listed for the hourly rating of the assembly penetrated, shall be of the same series as the run, and shall be installed so that the rated portion of the fitting lies within the thickness of the assembly as the listing requires.
−## Factory Testing {toc}
+### Where a through-penetration firestop system is selected, the system, its installation, and its inspection shall comply with [[sync/firestopping]], and the busway manufacturer shall confirm in writing that the system's packing and sealing materials in contact with the housing do not reduce the busway rating.
−### Each busway section shall be production-tested at the factory in accordance with UL 857, including dielectric withstand and continuity verification.
+### A run passing through a wall shall pass through in an unbroken length, with no joint within the wall thickness, as NFPA 70 368.10(C)(1) requires.
−### Certified factory test reports shall be furnished for each production run on request.
+# Identification {toc}
−## Field Testing {toc}
+## Nameplates, warning labels, and field-applied markings shall comply with [[sync/equipment-labeling]] for material, lettering, and attachment.
−### After installation and before energization, the complete busway run shall be tested for insulation resistance phase-to-phase and phase-to-ground.
+## Each straight length and fitting shall carry the manufacturer's marking of the voltage rating, the continuous current rating, and the manufacturer's name or trademark, placed so that it is visible after installation, as NFPA 70 368.120 requires.
−### Insulation resistance shall meet or exceed the manufacturer's minimum acceptance value for the rating and length installed.
+## Each run shall carry a nameplate at its source end stating the run designation, the system voltage with the number of phases and wires, the continuous current rating, the short-circuit current rating, and the source that feeds it, and the designation shall match the designation on the one-line diagram.
−### All bolted joints shall be verified to the manufacturer's specified torque value before energization, and the verification recorded.
+## Each run shall carry a marking at intervals not exceeding 50 ft along its length, and at each change of direction, stating the run designation and the system voltage, so that a run is identified at any point without tracing it to its source.
−### Loose joint hardware is the leading cause of busway failures; a thermal hot spot at an under-torqued joint cascades into insulation failure, so torque verification is mandatory, not optional. {note}
+## Each cable tap box, flanged end, and plug-in opening on a plug-in run shall carry a phase identification at the stabs, so that a plug-in unit or a conductor is landed on the intended phase.
−### Joints shall be re-torqued after the first full thermal load cycle and the re-torque recorded, because initial heating relaxes the joint hardware.
+## Arc-flash warning labels shall be applied at each cable tap box and at the source end of each plug-in run in accordance with NFPA 70 110.16 and NFPA 70E, with the values taken from the study performed under [[sync/arc-flash-study]].
+## Where the run 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, at the same intervals as the run designation.
+
+# Testing {toc}
+
+## Factory Tests {toc}
+
+### The manufacturer shall perform the production tests of UL 857 on every straight length and fitting before shipment, including a dielectric withstand test of the bus bars to the housing and between bars, and shall furnish a certified production test report for the lengths and fittings furnished with the closeout submittals.
+
+### The short-circuit current rating, the short-time withstand rating where one is furnished, and the temperature rise at rated current shall have been established by design test on the busway series under UL 857, and the manufacturer shall state in the product data the test reports on which each rating rests.
+
+## Field Acceptance Tests {toc}
+
+### Field acceptance tests shall be performed on every run after installation is complete, after every joint has been made up and every plug-in opening cover closed, and before the run is energized, in accordance with ANSI/NETA ATS and [[sync/electrical-acceptance-testing]], and shall include the tests indicated in the datasheet.
+
```datasheet
−label: Field Insulation Resistance Test
+label: Field Acceptance Tests
type: checkbox
options:
− - Phase-to-phase
− - Phase-to-ground
− - Neutral-to-ground
+ - "Visual and mechanical inspection including hanger spacing, restraint, joint covers, end closures, and opening covers"
+ - "Joint torque verification at every joint, or verification that every torque-indicating head has sheared, with the record kept by joint location"
+ - "Insulation resistance of each bar, phase-to-phase and phase-to-ground, with the neutral and the isolated ground bar tested to ground"
+ - "Contact resistance across every joint, every flanged end, and every tap box connection"
+ - "Phase sequence verification at every termination and at each end of every plug-in run"
+ - "Dielectric withstand test of the run after the insulation resistance test"
+ - "Ground path continuity from the far end of every run to the source"
default:
− - Phase-to-phase
− - Phase-to-ground
− - Neutral-to-ground
+ - "Visual and mechanical inspection including hanger spacing, restraint, joint covers, end closures, and opening covers"
+ - "Joint torque verification at every joint, or verification that every torque-indicating head has sheared, with the record kept by joint location"
+ - "Insulation resistance of each bar, phase-to-phase and phase-to-ground, with the neutral and the isolated ground bar tested to ground"
+ - "Contact resistance across every joint, every flanged end, and every tap box connection"
+ - "Phase sequence verification at every termination and at each end of every plug-in run"
+ - "Ground path continuity from the far end of every run to the source"
```
−```datasheet
−label: Joint Torque Value
−type: range
−unit: ft-lb
−min: 30
−max: 70
−step: 5
−default: 50
−```
+### Insulation resistance shall be measured for one minute at 1000 V DC on a run rated above 250 V and at 500 V DC on a run rated 250 V and below, with the run disconnected from the equipment at every termination, and a reading below the minimum ANSI/NETA ATS states for the voltage class shall be investigated before the run is energized.
+### A joint whose contact resistance exceeds the manufacturer's published value, or exceeds the lowest joint on the same run by more than 50%, shall be opened, cleaned, remade with new hardware, and retested before the run is energized.
+
+### A run 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.
+
+### Where plain bolts are selected in the datasheet, every joint shall be re-torqued to the manufacturer's value after the run has carried load through its first full thermal cycle and not later than 90 days after energization, and the re-torque record shall be added to the joint torque record.
+
+### A torque-indicating bolt is designed to hold its clamping force through thermal cycling without a second visit, and the manufacturers that furnish it state that no re-torque is required; a plain bolt relaxes as the joint heats and cools the first time, which is why the re-torque is required only where plain bolts are furnished. {note}
+
+### Infrared thermographic inspection shall be as indicated in the datasheet.
+
```datasheet
−label: Re-Torque After First Thermal Cycle
−type: checkbox
+label: Infrared Thermographic Inspection
+type: select
options:
− - Required and recorded
−default:
− - Required and recorded
+ - "Not required"
+ - "One inspection within 90 days of energization"
+ - "One inspection within 90 days of energization and a second at eleven months"
```
+### Where infrared inspection is indicated, it shall be performed with the run carrying not less than 40% of its continuous current rating, shall scan every joint, every flanged end, every tap box, and every installed plug-in unit, and every connection showing a rise of more than 10 °C above its neighbors shall be reported and corrected.
+
+### A joint that was made up short of its torque runs hotter than its neighbors from the first day of load, and the only test that finds it with the run in service is a scan under load; a second inspection near the end of the first year finds the joint that loosened through the first full cycle of seasonal load, which the first inspection cannot see, and it costs a second visit under load and a warranty claim filed before the warranty ends. {note}
+
# Installation {toc}
−## Busway shall be installed in accordance with NFPA 70 Article 368, NEMA BU 1.1, and the manufacturer's installation instructions.
+## Routing and Accessibility {toc}
−## Busway shall be installed with the housing in the orientation for which the run is rated; some products are derated when mounted on edge or flat.
+### Busway shall be installed in accordance with NFPA 70 Article 368, NEMA BU 1.1, and the manufacturer's installation instructions, and shall be located in the open and visible except where NFPA 70 368.10(B) permits a run behind an access panel.
−## Busway shall not be installed in hoistways, in ducts used for environmental air handling except as permitted by Article 368, or where subject to physical damage.
+### Where a run is installed behind an access panel, the panels shall be removable, every joint and every plug-in unit shall be accessible through a panel, the run shall be of non-ventilated construction, and no plug-in unit carrying an overcurrent device shall be installed behind the panel unless NFPA 70 368.10(B) permits it there.
−## The complete routing, mounting elevations, and fitting arrangement shall follow [[drawing: busway routing and elevations]].
+### Busway shall not be installed where it is subject to severe physical damage, in a hoistway, in a hazardous classified location, or in a location NFPA 70 368.12 prohibits, and where the routing shown on the drawings passes through such a location the Contractor shall report the conflict to the Engineer of Record before the run is released for manufacture.
−## Support and Suspension {toc}
+### Where a run is installed in a space used for environmental air, the run shall be of non-ventilated construction as NFPA 70 300.22(C) requires, and no plug-in unit shall be installed in that space unless the unit is listed for it.
−### Busway shall be supported at intervals not exceeding the manufacturer's maximum spacing and not exceeding the spacing required by NFPA 70 Article 368.30.
+### The working space in front of every cable tap box and every plug-in unit shall comply with NFPA 70 110.26 for the system voltage, and no run shall be routed through the working space or the dedicated electrical space of other equipment.
−### Horizontal runs and vertical risers have different support requirements; vertical risers require spring-cushioned hangers at each floor to carry the dead weight and absorb thermal movement. {note}
+## Hangers and Supports {toc}
−### Vertical riser busway shall be supported at each floor penetration with the manufacturer's spring-type hanger assembly.
+### Each run shall be supported by hangers furnished or designated by the busway manufacturer for the series, at intervals not exceeding the manufacturer's published spacing for the orientation installed and in no case exceeding the interval NFPA 70 368.30 permits for the busway as marked.
−### Inadequate support spacing and missing seismic bracing are frequently missed on ceiling-mounted runs; verify hanger spacing and seismic restraint before energization. {note}
+### Hangers shall attach to the housing only at the points the manufacturer designates, and no hanger shall bear on a joint, a joint cover, a plug-in opening cover, or an expansion fitting.
−### Where the seismic design category requires it, busway supports shall be braced and anchored in accordance with the IBC and ASCE 7.
+### Hangers shall be supported from the building structure, and the Contractor shall confirm with the Engineer of Record that the structure at each hanger carries the weight per foot of the run, the plug-in units it will carry, and the seismic load where restraint is required, before the hangers are installed.
−```datasheet
−label: Mounting Orientation
−type: select
−options:
− - Horizontal, flat
− - Horizontal, edgewise
− - Vertical riser
−default: Horizontal, edgewise
−```
+### Where a horizontal run is suspended, the hangers shall allow the run to be leveled and aligned so that every joint closes square, and a run shall not be sprung into alignment at a joint.
−```datasheet
−label: Maximum Support Spacing
−type: range
−unit: ft
−min: 5
−max: 10
−step: 1
−default: 5
−```
+### Hangers for a run installed outdoors or in a corrosive atmosphere shall be of a material or finish suitable for the exposure, and no dissimilar-metal contact shall be left between a hanger and an aluminum housing without an isolating washer or a coating.
−```datasheet
−label: Seismic Bracing Required
−type: select
−options:
− - Not required
− - Required per IBC / ASCE 7
−default: Not required
−```
+## Vertical Risers {toc}
−## Penetrations {toc}
+### A vertical riser shall be supported at every floor it passes through by the manufacturer's spring-type riser hanger assembly, with the hangers set so that the dead weight of the riser is shared among the floors as the manufacturer's instructions require, and so that the riser is free to move with temperature between the hangers.
−### Where busway passes through a fire-rated floor or wall, a UL-listed fire-stop system shall be installed in accordance with NFPA 70 Section 300.21 and the IBC.
+### Where the riser height or the conductor material exceeds the manufacturer's limit for spring hangers alone, the riser shall be fixed at the point the manufacturer designates and sprung above and below it, and the arrangement shall be shown on the shop drawings.
−### Failing to specify and install the fire-stop method at rated penetrations is a routine cause of AHJ rejection and costly field remediation; the system, not just a sleeve, must be listed for the assembly.
+### A riser through two or more dry floors, other than in an industrial establishment, shall be enclosed by a curb not less than 4 in. high around every floor opening, located within 12 in. of the opening, as NFPA 70 368.10(C)(2) requires, and the curb shall be shown on the shop drawings so that the trade constructing the floor furnishes it.
−### Through-floor penetrations shall include a curb or barrier at least 100 mm (4 in.) high to prevent liquids from entering the floor opening, as required by NFPA 70 Article 368.10.
+### A riser shall be of non-ventilated construction through each floor and for not less than 6 ft above it, and no joint shall be located within the floor thickness.
−### The fire-stop method shall be coordinated with the AHJ for the specific floor or wall assembly penetrated.
+### A riser hangs its full weight on the floors it passes through, and the bars grow with temperature along the full height, so a riser that is pinned at every floor carries the growth into the joints and a riser hung from the top alone carries its whole weight on the top floor; the spring hangers at every floor are what let the weight be shared and the growth be absorbed, which is why a riser hanger is not a horizontal hanger turned sideways. {note}
−```datasheet
−label: Fire-Barrier Penetration Method
−type: select
−options:
− - Listed sleeve and fire-stop system
− - Poke-through firestop device
− - Intumescent wrap system
−default: Listed sleeve and fire-stop system
−```
+## Connections to Equipment {toc}
−## Labeling {toc}
+### Before a flanged end is bolted to the equipment flange, the Contractor shall confirm that the phase sequence of the busway bars matches the phase sequence of the equipment bus, that the neutral and ground positions match, and that the two flanges align without forcing, and a mismatch shall be reported to the Engineer of Record before the connection is made.
−### Each busway run shall be labeled at its origin with the ampere rating, voltage, phase configuration, and source identification, in accordance with [[sync/equipment-labeling]].
+### The connection at every flanged end and cable tap box shall be torqued to the manufacturer's published value with a calibrated torque tool, and the values applied shall be recorded in the joint torque record.
−### Plug-in units shall be labeled with the served load identification and the source busway run.
+### No run shall be used to support, align, or restrain the equipment it terminates at, and the equipment shall be anchored before the flanged end is connected to it.
−### Arc-flash and shock-hazard warning labels shall be applied in accordance with NFPA 70E.
+### Every shipping cover, desiccant, and temporary protection shall be removed before a joint is made up, and every joint cover, end closure, and opening cover shall be in place before the run is energized.
# Delivery, Storage, and Handling {toc}
−## Busway sections shall be delivered in the manufacturer's original protective packaging with the listing label and section identification intact.
+## Each straight length and fitting shall be delivered in the manufacturer's packaging with the listing marks and the section identification intact, with the joint contact surfaces protected, and shall be inspected for shipping damage at receipt.
−## Busway shall be stored indoors in a clean, dry, heated space and shall be protected from moisture, dust, and physical damage until installed.
+## Busway shall be stored indoors in a clean, dry space where the temperature is held above the dew point, stacked as the manufacturer's instructions permit, 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.
−## Busway insulation absorbs moisture in storage; energizing a damp run can fail the dielectric, so moisture control before energization is essential. {note}
+## Busway shall be handled and lifted in accordance with NEMA BU 1.1 and the manufacturer's instructions, by the lifting points or the housing as the manufacturer designates, and never by a joint, a joint cover, a plug-in opening cover, or the exposed bars at the end of a length.
−## Busway that has been exposed to moisture shall be dried and shall pass an insulation resistance test before energization.
+## A length or fitting that has been wetted, dropped, or bent in transit, in storage, or in handling shall be set aside, and shall be repaired or replaced as the manufacturer directs and as the Engineer of Record accepts in writing.
−## Busway shall be handled and rigged in accordance with NEMA BU 1.1 and the manufacturer's instructions, using only the designated lifting points.
+## A length whose insulation has absorbed moisture shall be dried as the manufacturer directs and shall pass the insulation resistance test before it is joined to the run.
+## The bars of a non-ventilated busway sit close together under insulation that holds moisture when a length is stored damp, and a run assembled from damp lengths fails its insulation resistance test or fails under voltage at the first joint that holds water; the moisture is removed before the length is joined, not after the run is complete. {note}
+
# Warranty {toc}
−## The manufacturer shall warrant the busway against defects in materials and workmanship for the specified warranty period from the date of substantial completion.
+## The manufacturer shall warrant each run, including every straight length, fitting, joint, and end closure, against defects in materials and workmanship for the period indicated in the datasheet.
−## The warranty shall cover repair or replacement of defective sections, fittings, and plug-in units, including the bus bars, insulation, and joint hardware.
+```datasheet
+label: Manufacturer's Warranty Period
+type: range
+unit: years
+options:
+ min: 1
+ max: 5
+ setpoints: [1, 2, 3, 5]
+```
+## 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 Period
+label: Warranty Commencement
type: select
−unit: years
options:
− - 1
− - 2
− - 5
−default: 1
+ - "Date of substantial completion"
+ - "Date of energization"
+ - "Date of shipment"
```
−# Spare Parts {toc}
+## Warranty commencement at shipment is the manufacturer's usual term, and it consumes the warranty while the lengths sit in storage and the run is assembled; commencement at energization or substantial completion moves the coverage to the period the Owner is operating the run, and the manufacturer prices the added months into the busway. {note}
−## The Contractor shall furnish spare plug-in units and joint hardware so that future load additions and joint maintenance do not require a long procurement lead time.
+## The Contractor shall warrant the installation, including every joint made up in the field, every hanger, every restraint, and every termination, for the project warranty period.
−## The Contractor shall furnish spare plug-in opening covers, joint hardware kits, and antioxidant compound where aluminum bus is specified.
+## A length, fitting, or joint 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 run.
−## The Contractor shall furnish spare plug-in units of the specified ratings where future load growth is anticipated.
+# Spare Parts {toc}
+## The Contractor shall deliver the spare parts indicated in the datasheet to the Owner before the runs are accepted, and shall obtain a signed receipt for them.
+
```datasheet
−label: Spare Parts to Furnish
+label: Spare Parts to Be Furnished
type: checkbox
options:
− - Plug-in opening covers
− - Joint hardware kits
− - Antioxidant compound (aluminum bus)
− - Spare plug-in units
+ - "One complete joint hardware kit for every ten joints installed, and not fewer than two"
+ - "Two plug-in opening covers of each type installed"
+ - "One end closure of each rating and enclosure type installed"
+ - "One joint cover of each type installed"
+ - "One pint of touch-up paint matching the finish"
default:
− - Plug-in opening covers
− - Joint hardware kits
+ - "One complete joint hardware kit for every ten joints installed, and not fewer than two"
+ - "Two plug-in opening covers of each type installed"
```
+
+## Spare parts shall be identical to and interchangeable with the installed parts, shall be delivered in their original packaging, and shall be labeled with the busway series, the rating, and the run designation they serve.
+
+## Spare plug-in units are furnished under [[sync/feeder-busway-plug-in-units]]; the spares under this standard are the parts that let a joint be remade or a run be extended without waiting on the manufacturer's lead time. {note}