+---
+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.
+---
+
+# 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}
+
+## 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 shall comply with UL 857 and the applicable provisions of NEMA BU 1 for the listed type, voltage, and ampere rating specified.
+
+## 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}
+
+## This standard does not cover the following, which are specified elsewhere: {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 [[syncs/low-voltage-switchboards]], [[syncs/low-voltage-panelboards]])
+
+## Related distribution and protection requirements are addressed in [[syncs/low-voltage-switchboards]], [[syncs/low-voltage-panelboards]], [[syncs/conductors-and-cables]], [[syncs/grounding-and-bonding]], and [[syncs/equipment-labeling]]. {note}
+
+# 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}
+
+| 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) |
+| 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 |
+
+# Submittals {toc}
+
+## Action Submittals {toc}
+
+### The Contractor shall submit the following action submittals for review before fabrication:
+
+- 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
+
+```datasheet
+label: Action Submittals Required
+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
+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 shall be coordinated against [[drawing: busway riser and plan routing]] before fabrication so that field-measured lengths and fitting locations are confirmed.
+
+## Closeout Submittals {toc}
+
+### The Contractor shall submit the following closeout submittals before final acceptance:
+
+- 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
+
+```datasheet
+label: Closeout Submittals Required
+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
+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
+```
+
+## Informational Submittals {toc}
+
+### The Contractor shall submit the following informational submittals:
+
+- 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
+
+```datasheet
+label: Informational Submittals Required
+type: checkbox
+options:
+ - Certification of compliance (UL 857, NEMA BU 1)
+ - Short-circuit study correlation
+ - Installer qualification statements
+ - Field quality-control test plan
+default:
+ - Certification of compliance (UL 857, NEMA BU 1)
+ - Short-circuit study correlation
+ - Field quality-control test plan
+```
+
+# 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.
+
+## 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 and its fittings shall be listed and labeled by a Nationally Recognized Testing Laboratory under UL 857.
+
+## 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.
+
+## 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}
+
+## 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.
+
+## Manufacturer qualification: the manufacturer shall have produced UL 857-listed busway of the specified type and rating for not less than five years.
+
+# Environmental and Service Conditions {toc}
+
+## 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. {note}
+
+## Standard busway is rated for operation in a maximum ambient air temperature of 40 °C unless a higher-ambient rating is specified.
+
+## 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.
+
+## 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.
+
+## Outdoor and wet-location busway shall use a weatherproof enclosure listed for the location, with drain provisions and gasketed joints.
+
+## Select the enclosure type to match the installed environment; an indoor feeder housing relocated outdoors will admit water at the joints and fail. {note}
+
+```datasheet
+label: Installation Environment
+type: select
+options:
+ - Indoor, dry, ventilated
+ - Indoor, high-ambient (>40 °C)
+ - Outdoor, weatherproof (NEMA 3R)
+ - Corrosive or washdown area
+default: Indoor, dry, ventilated
+```
+
+```datasheet
+label: Maximum Ambient Air Temperature
+type: range
+unit: °C
+min: 30
+max: 60
+step: 5
+default: 40
+```
+
+```datasheet
+label: Enclosure Type
+type: select
+options:
+ - Ventilated indoor feeder
+ - Ventilated indoor plug-in
+ - Totally enclosed (non-ventilated)
+ - Weatherproof NEMA 3R
+default: Ventilated indoor feeder
+```
+
+# Ratings and Electrical Characteristics {toc}
+
+## Voltage and System Configuration {toc}
+
+### The busway voltage rating shall equal or exceed the nominal system voltage at the point of installation.
+
+### Standard low-voltage busway is rated 600 V or less; systems above 600 V require medium-voltage bus outside this scope. {note}
+
+### The number of poles and the neutral configuration shall match the system and the load characteristics served.
+
+```datasheet
+label: System Voltage
+type: select
+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
+```
+
+```datasheet
+label: Pole and Neutral Configuration
+type: select
+options:
+ - 3-pole, 3-wire (no neutral)
+ - 4-pole, 100% neutral
+ - 4-pole, 200% (double) neutral
+default: 4-pole, 100% neutral
+```
+
+### 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.
+
+### 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}
+
+## Ampere Rating {toc}
+
+### The continuous ampere rating shall be selected from the manufacturer's standard catalog ratings and shall equal or exceed the calculated feeder load.
+
+### 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}
+
+### The conductor material shall be specified, because it governs cross-section, weight, support spacing, and termination preparation.
+
+```datasheet
+label: Continuous Ampere Rating
+type: select
+unit: A
+options:
+ - 225
+ - 400
+ - 600
+ - 800
+ - 1000
+ - 1200
+ - 1350
+ - 1600
+ - 2000
+ - 2500
+ - 3000
+ - 4000
+ - 5000
+default: 1600
+```
+
+```datasheet
+label: Conductor Material
+type: select
+options:
+ - Copper
+ - Aluminum
+default: Copper
+```
+
+### 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.
+
+### 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. {note}
+
+## 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.
+
+### 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.
+
+### 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}
+
+### The SCCR shall be expressed in symmetrical RMS amperes and shall be referenced to the fault-clearing time of the upstream overcurrent device.
+
+### 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}
+
+```datasheet
+label: Short-Circuit Current Rating (SCCR)
+type: select
+unit: kA
+options:
+ - 22
+ - 42
+ - 65
+ - 85
+default: 65
+```
+
+```datasheet
+label: Bracing Basis (Fault-Clearing Time)
+type: select
+options:
+ - 3-cycle
+ - 6-cycle
+default: 3-cycle
+```
+
+### The available fault current at the busway origin shall be confirmed against [[drawing: one-line diagram fault values]] before the SCCR is finalized.
+
+# Construction {toc}
+
+## Bus Bars {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.
+
+### 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.
+
+### Joint plating prevents the contact resistance from rising as the bare base metal oxidizes; an unplated joint runs hot and loosens over time. {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.
+
+### Bus bar insulation shall be a flame-retardant material with a temperature rating not less than the maximum bus operating temperature.
+
+```datasheet
+label: Joint Contact Plating
+type: select
+options:
+ - Tin-plated
+ - Silver-plated
+default: Tin-plated
+```
+
+```datasheet
+label: Bus Bar Temperature Rise (over 40 °C ambient)
+type: range
+unit: °C
+min: 55
+max: 65
+step: 5
+default: 55
+```
+
+## Housing {toc}
+
+### 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.
+
+### 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}
+
+### The housing finish shall be a corrosion-resistant coating suitable for the installed environment.
+
+### 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.
+
+```datasheet
+label: Housing Material
+type: select
+options:
+ - Steel
+ - Aluminum
+default: Steel
+```
+
+```datasheet
+label: Plug-In Opening Interval
+type: select
+unit: in
+options:
+ - 12
+ - 18
+ - 24
+default: 24
+```
+
+```datasheet
+label: Plug-In Opening Sides
+type: select
+options:
+ - One side
+ - Both sides
+default: One side
+```
+
+## Grounding {toc}
+
+### 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.
+
+### Where the served load is sensitive electronic equipment, a separate insulated (isolated) ground bus bar shall be provided in addition to the housing ground.
+
+### 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}
+
+### Grounding and bonding of the busway shall comply with [[syncs/grounding-and-bonding]] and NFPA 70 Article 250.
+
+```datasheet
+label: Grounding Arrangement
+type: select
+options:
+ - Housing as equipment ground
+ - Internal ground bus bar
+ - Internal ground bus plus isolated ground bus
+default: Internal ground bus bar
+```
+
+## Fittings {toc}
+
+### Elbows, tees, offsets, and transformer or switchboard taps shall be factory-fabricated fittings of the same series, rating, and listing as the straight busway.
+
+### Field-fabricated fittings are prohibited; the bracing and joint geometry of a busway run are validated only as a manufactured assembly.
+
+### End closures (dead ends) shall be installed at every unused open end of the busway to maintain the enclosure and isolate the live bus.
+
+### 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.
+
+### 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}
+
+```datasheet
+label: Phase Transposition Section
+type: select
+options:
+ - Not required (balanced tapping)
+ - Required (one-sided plug-in run)
+default: Not required (balanced tapping)
+```
+
+## Expansion Fittings {toc}
+
+### 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}
+
+### Expansion fittings shall be provided on long straight runs at the manufacturer's maximum spacing for the expected temperature differential.
+
+### Expansion fittings shall be provided where a busway run crosses a building expansion joint, in accordance with NFPA 70 Section 300.7(B).
+
+### 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}
+
+```datasheet
+label: Expansion Fitting Spacing (long straight runs)
+type: range
+unit: ft
+min: 50
+max: 100
+step: 25
+default: 75
+```
+
+```datasheet
+label: Expansion Fitting at Building Expansion Joint
+type: checkbox
+options:
+ - Required where run crosses a building expansion joint
+default:
+ - Required where run crosses a building expansion joint
+```
+
+# Plug-In Units {toc}
+
+## 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. {note}
+
+## 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.
+
+## 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.
+
+## 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.
+
+## 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}
+
+## Plug-in units shall include an interlock that prevents insertion or removal while the unit is in the ON position.
+
+## 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}
+
+```datasheet
+label: Plug-In Unit Disconnect Type
+type: select
+options:
+ - Fusible switch
+ - Molded-case circuit breaker
+default: Molded-case circuit breaker
+```
+
+```datasheet
+label: Fusible Unit Fuse Class
+type: select
+options:
+ - Class J
+ - Class RK1
+ - Class RK5
+default: Class J
+```
+
+```datasheet
+label: Plug-In Unit Ampere Rating
+type: select
+unit: A
+options:
+ - 30
+ - 60
+ - 100
+ - 200
+ - 400
+ - 600
+ - 800
+ - 1200
+ - 1600
+default: 100
+```
+
+```datasheet
+label: Plug-In Unit Poles
+type: select
+options:
+ - 2-pole
+ - 3-pole
+default: 3-pole
+```
+
+## Plug-in unit locations shall be coordinated against [[drawing: plug-in unit plan locations]].
+
+# Testing {toc}
+
+## Factory Testing {toc}
+
+### Each busway section shall be production-tested at the factory in accordance with UL 857, including dielectric withstand and continuity verification.
+
+### Certified factory test reports shall be furnished for each production run on request.
+
+## Field Testing {toc}
+
+### After installation and before energization, the complete busway run shall be tested for insulation resistance phase-to-phase and phase-to-ground.
+
+### Insulation resistance shall meet or exceed the manufacturer's minimum acceptance value for the rating and length installed.
+
+### All bolted joints shall be verified to the manufacturer's specified torque value before energization, and the verification recorded.
+
+### 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}
+
+### Joints shall be re-torqued after the first full thermal load cycle and the re-torque recorded, because initial heating relaxes the joint hardware.
+
+```datasheet
+label: Field Insulation Resistance Test
+type: checkbox
+options:
+ - Phase-to-phase
+ - Phase-to-ground
+ - Neutral-to-ground
+default:
+ - Phase-to-phase
+ - Phase-to-ground
+ - Neutral-to-ground
+```
+
+```datasheet
+label: Joint Torque Value
+type: range
+unit: ft-lb
+min: 30
+max: 70
+step: 5
+default: 50
+```
+
+```datasheet
+label: Re-Torque After First Thermal Cycle
+type: checkbox
+options:
+ - Required and recorded
+default:
+ - Required and recorded
+```
+
+# Installation {toc}
+
+## General {toc}
+
+### Busway shall be installed in accordance with NFPA 70 Article 368, NEMA BU 1.1, and the manufacturer's installation instructions.
+
+### 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 not be installed in hoistways, in ducts used for environmental air handling except as permitted by Article 368, or where subject to physical damage.
+
+### The complete routing, mounting elevations, and fitting arrangement shall follow [[drawing: busway routing and elevations]].
+
+## Support and Suspension {toc}
+
+### 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.
+
+### 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}
+
+### Vertical riser busway shall be supported at each floor penetration with the manufacturer's spring-type hanger assembly.
+
+### Inadequate support spacing and missing seismic bracing are frequently missed on ceiling-mounted runs; verify hanger spacing and seismic restraint before energization. {note}
+
+### Where the seismic design category requires it, busway supports shall be braced and anchored in accordance with the IBC and ASCE 7.
+
+```datasheet
+label: Mounting Orientation
+type: select
+options:
+ - Horizontal, flat
+ - Horizontal, edgewise
+ - Vertical riser
+default: Horizontal, edgewise
+```
+
+```datasheet
+label: Maximum Support Spacing
+type: range
+unit: ft
+min: 5
+max: 10
+step: 1
+default: 5
+```
+
+```datasheet
+label: Seismic Bracing Required
+type: select
+options:
+ - Not required
+ - Required per IBC / ASCE 7
+default: Not required
+```
+
+## Penetrations {toc}
+
+### 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.
+
+### 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. {note}
+
+### 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.
+
+### The fire-stop method shall be coordinated with the AHJ for the specific floor or wall assembly penetrated.
+
+```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
+```
+
+## Labeling {toc}
+
+### Each busway run shall be labeled at its origin with the ampere rating, voltage, phase configuration, and source identification, in accordance with [[syncs/equipment-labeling]].
+
+### Plug-in units shall be labeled with the served load identification and the source busway run.
+
+### Arc-flash and shock-hazard warning labels shall be applied in accordance with NFPA 70E.
+
+# 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.
+
+## Busway shall be stored indoors in a clean, dry, heated space and shall be protected from moisture, dust, and physical damage until installed.
+
+## Busway insulation absorbs moisture in storage; energizing a damp run can fail the dielectric, so moisture control before energization is essential. {note}
+
+## Busway that has been exposed to moisture shall be dried and shall pass an insulation resistance test before energization.
+
+## Busway shall be handled and rigged in accordance with NEMA BU 1.1 and the manufacturer's instructions, using only the designated lifting points.
+
+# 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 warranty shall cover repair or replacement of defective sections, fittings, and plug-in units, including the bus bars, insulation, and joint hardware.
+
+```datasheet
+label: Warranty Period
+type: select
+unit: years
+options:
+ - 1
+ - 2
+ - 5
+default: 1
+```
+
+# Spare Parts {toc}
+
+## 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. {note}
+
+## The Contractor shall furnish spare plug-in opening covers, joint hardware kits, and antioxidant compound where aluminum bus is specified.
+
+## The Contractor shall furnish spare plug-in units of the specified ratings where future load growth is anticipated.
+
+```datasheet
+label: Spare Parts to Furnish
+type: checkbox
+options:
+ - Plug-in opening covers
+ - Joint hardware kits
+ - Antioxidant compound (aluminum bus)
+ - Spare plug-in units
+default:
+ - Plug-in opening covers
+ - Joint hardware kits
+```