Enclosed Switches and Disconnects
Rewritten so device family and overcurrent protection are separate decisions, ratings come from the drawings instead of numeric lists, and service rules stay with the service-entrance standard; manual and double-throw transfer switches are owned here.
Showing changes from Rev 3
to Rev 4
in Enclosed Switches and Disconnects.
---
title: Enclosed Switches and Disconnects
category: Electrical / Power Distribution Equipment
−toc_depth: 3
description: >
− When to use: Enclosed low-voltage (600V and below) safety and disconnect switches and enclosed molded-case switches applied as service, feeder, and equipment disconnecting means in commercial, institutional, and industrial facilities. Covers fusible and non-fusible switches; heavy-duty and general-duty classes and where each is appropriate; horsepower, ampere, and voltage ratings from 30A through 1200A; short-circuit current rating (SCCR), series ratings, and the role of the upstream current-limiting fuse class (Class R, J, T, L) in establishing a high SCCR; number of poles and solid versus switched neutral; service-entrance-rated switches with neutral bonding and equipment grounding; enclosure selection to NEMA 250 (Types 1, 3R, 4, 4X stainless and nonmetallic, 12) by environment; defeatable and non-defeatable door interlocks; provisions for lockout/tagout per OSHA 1910.147 and line-side isolation; visible-blade indication; and the disconnecting means required at HVAC and rooftop units. Listed to UL 98, with enclosures to UL 50 and UL 50E and construction to NEMA KS 1, and applied per NFPA 70 Articles 404, 408, 430 Part IX, and 440.
+ When to use: Individually enclosed disconnecting means rated 1000 V and below, furnished as separate products rather than as part of an assembly: fusible and non-fusible safety switches listed to UL 98 in heavy-duty and general-duty construction, enclosed molded-case circuit breakers and molded-case switches listed to UL 489 and applied as stand-alone disconnects, manual motor controllers listed to UL 508 and marked suitable as motor disconnects, double-throw safety switches and manual transfer switches, and the fuses installed in them, serving feeders, motors, air-conditioning and refrigeration equipment, elevators, electric vehicle supply equipment, and other utilization equipment. Covers the device family and duty class, the overcurrent provision, the voltage, ampere, horsepower, and short-circuit ratings, poles and neutral, fuse class and clips, the operating handle, lockout and door interlock, accessories, the enclosure, identification, factory and field testing, installation, warranty, and spares, for indoor and outdoor locations.
− Not intended for: Panelboards (see [[sync/panelboards]]); metal-enclosed switchboards and switchgear; medium-voltage switches and load interrupters above 600V; molded-case circuit breakers applied as branch or feeder overcurrent protection; and automatic and manual transfer switches (see [[sync/automatic-transfer-switches]]).
+ Not intended for: cabinet-mounted assemblies that subdivide a feeder and hold an overcurrent device for each branch ([[sync/panelboards]]); dead-front switchboards and metal-enclosed switchgear ([[sync/low-voltage-switchboards]], [[sync/low-voltage-switchgear]]); starters that package a disconnect, a branch-circuit protective device, and a contactor in one listed enclosure ([[sync/combination-motor-starters]]); automatic transfer switches ([[sync/automatic-transfer-switches]]); switching and interrupting equipment above 1000 V ([[sync/metal-enclosed-interrupter-switchgear]], [[sync/medium-voltage-switchgear]]); the rules that make a disconnect service equipment, including the service disconnect location, grouping, marking, and ground-fault protection of equipment at the service ([[sync/electrical-service-entrance]]); the DC disconnects and rapid shutdown equipment of a photovoltaic array ([[sync/photovoltaic-systems]]); the disconnect a packaged unit carries from its factory, which belongs to the standard governing that unit; the classification of a hazardous location ([[sync/electrical-hazardous-locations]]); and the short-circuit, coordination, and arc-flash studies that establish the ratings ([[sync/short-circuit-study]], [[sync/protective-coordination-study]], [[sync/arc-flash-study]]).
---
# Scope {toc}
−## This standard covers the materials, ratings, configuration, installation, and testing of individually enclosed low-voltage switches and disconnects rated 600V and below and used as service, feeder, motor, and equipment disconnecting means. {note}
+## This standard governs the enclosed disconnect as a listed product: the switch or breaker mechanism, the fuses and fuse clips where the disconnect is fusible, the operating handle and its lockout provision, the door interlock, the accessories, the enclosure, and the field work that puts the disconnect into service. {note}
−## The work includes fusible and non-fusible enclosed safety switches, enclosed molded-case switches, and the door interlocks, lockout provisions, neutral and grounding arrangements, and enclosures that accompany them. {note}
+## A disconnecting means is a function NFPA 70 assigns at a service, a feeder, a motor, an appliance, or a piece of equipment, and the products in this standard are the ones furnished to perform it where the function is not already built into a panelboard, a switchboard, a starter, or the equipment itself. A fusible switch and an enclosed circuit breaker perform the function and also carry the overcurrent protection of the circuit; a non-fusible switch and a molded-case switch isolate only, and the overcurrent device upstream protects the circuit through them. {note}
−## An enclosed switch provides a manually operable, visible, and lockable means of disconnecting a circuit or piece of equipment from its supply; a fusible switch additionally provides branch or feeder overcurrent protection through its fuses. {note}
+## Most projects have many disconnects, and the values that differ from one to the next, such as the voltage, the ampere rating, the horsepower, the fuse rating, and the enclosure the location calls for, live on the one-line diagram and the equipment schedules; the datasheet of this standard carries the policy that applies to every disconnect on the project unless a drawing states otherwise for a particular one. {note}
−## Enclosed switches shall be listed and labeled to UL 98 by a Nationally Recognized Testing Laboratory.
+## The following are governed elsewhere and are outside this standard: {note}
−## Enclosed switches shall be applied and installed in accordance with NFPA 70, including Article 404 for switches, Article 408 where the switch is part of distribution equipment, Article 430 Part IX for motor disconnecting means, and Article 440 for air-conditioning and refrigerating equipment.
+- the panelboard that supplies the feeder or the branch conductors ahead of the disconnect, under [[sync/panelboards]]
+- switchboards, switchgear, and motor control centers, under [[sync/low-voltage-switchboards]], [[sync/low-voltage-switchgear]], and [[sync/motor-control-centers]]
+- the starter that packages a disconnect, a branch-circuit protective device, and a contactor in one listed enclosure, under [[sync/combination-motor-starters]]
+- the disconnect and bypass provisions built into a variable frequency drive, under [[sync/hvac-variable-frequency-drives]] and [[sync/low-voltage-variable-frequency-drives]]
+- automatic transfer switches, under [[sync/automatic-transfer-switches]]
+- everything that makes a disconnect service equipment beyond the product listing, including where the service disconnect is located, how many there are, how they are marked, and the ground-fault protection of equipment at the service, under [[sync/electrical-service-entrance]]
+- the DC disconnects, the rapid shutdown equipment, and the AC disconnect of a photovoltaic system, under [[sync/photovoltaic-systems]]
+- the conductors that land in the disconnect and their terminations, under [[sync/conductors-and-cables]]
+- the raceways entering the enclosure, under [[sync/raceways-and-conduit]]
+- the equipment grounding conductor, the bonding of the enclosure, and the main bonding jumper of a service, under [[sync/grounding-and-bonding]]
+- the classification of a hazardous location and the wiring methods inside it, under [[sync/electrical-hazardous-locations]]
+- the disconnect a packaged unit carries from its factory, under the standard governing that unit
+- the short-circuit, protective device coordination, and arc-flash incident energy studies, under [[sync/short-circuit-study]], [[sync/protective-coordination-study]], and [[sync/arc-flash-study]]
+- nameplate and label material, lettering, and attachment, under [[sync/electrical-identification]]
−## A non-fusible switch contains no overcurrent device and depends entirely on an upstream overcurrent protective device for short-circuit and overload protection; it provides isolation only. {note}
+## The location of each disconnect shall be as indicated on [[drawing: the electrical plans]].
−## Assemblies Covered {toc}
+## Where a value stated on the one-line diagram or an equipment schedule for a particular disconnect differs from the datasheet selection under this standard, the drawing shall govern for that disconnect.
−### Switches covered by this standard are individually enclosed air switches, manually operable by an external handle, with all current-carrying parts enclosed, rated 600V and below and 1200A and below. {note}
−
−### For assemblies that subdivide a feeder into branch circuits with individual overcurrent devices, see [[sync/panelboards]]. {note}
−
−### For drawout power circuit breaker assemblies and higher fault-duty distribution, the switch is part of switchboard or switchgear scope and is not covered here. {note}
−
−## Related Systems {toc}
−
−### Line and load conductors terminating in the switch shall comply with [[sync/conductors-and-cables]].
−
−### Raceways and conduit entering the switch enclosure shall comply with [[sync/raceways-and-conduit]].
−
−### Switches serving motor loads fed from motor control centers shall be coordinated with [[sync/motor-control-centers]].
−
−### The equipment grounding and any service or system bonding at the switch shall comply with [[sync/grounding-and-bonding]].
−
−### Switch identification and warning labels shall follow [[sync/equipment-labeling]].
−
−### The available fault current used to select the switch SCCR and any series rating shall be taken from the project arc-flash and short-circuit study per [[sync/arc-flash-study]].
−
# Referenced Standards {toc}
−## Equipment, materials, and installation shall comply with the latest adopted edition of the following standards and codes.
+## 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 |
|----------|-------|
−| NFPA 70 | National Electrical Code (Articles 110, 230, 240, 250, 404, 408, 430, 440) |
−| NFPA 70E | Standard for Electrical Safety in the Workplace |
−| UL 98 | Standard for Enclosed and Dead-Front Switches |
−| UL 50 | Standard for Enclosures for Electrical Equipment, Non-Environmental Considerations |
−| UL 50E | Standard for Enclosures for Electrical Equipment, Environmental Considerations |
−| UL 248-1 | Low-Voltage Fuses, General Requirements |
−| NEMA KS 1 | Enclosed and Miscellaneous Distribution Equipment Switches (600V Maximum) |
+| UL 98 | Enclosed and Dead-Front Switches |
+| UL 489 | Molded-Case Circuit Breakers, Molded-Case Switches, and Circuit-Breaker Enclosures |
+| UL 508 | Industrial Control Equipment |
+| UL 1008 | Transfer Switch Equipment |
+| UL 869A | Reference Standard for Service Equipment |
+| UL 248-1 | Low-Voltage Fuses - Part 1: General Requirements |
+| UL 248-4 | Low-Voltage Fuses - Part 4: Class CC Fuses |
+| UL 248-6 | Low-Voltage Fuses - Part 6: Class H Non-Renewable Fuses |
+| UL 248-8 | Low-Voltage Fuses - Part 8: Class J Fuses |
+| UL 248-10 | Low-Voltage Fuses - Part 10: Class L Fuses |
+| UL 248-12 | Low-Voltage Fuses - Part 12: Class R Fuses |
+| UL 248-15 | Low-Voltage Fuses - Part 15: Class T Fuses |
+| UL 50 | Enclosures for Electrical Equipment, Non-Environmental Considerations |
+| UL 50E | Enclosures for Electrical Equipment, Environmental Considerations |
+| NEMA KS 1 | Heavy Duty Enclosed and Dead-Front Switches (600 Volts Maximum) |
+| NEMA KS 3 | Guidelines for Inspection and Preventive Maintenance of Switches Used in Commercial and Industrial Applications |
+| NEMA AB 1 | Molded-Case Circuit Breakers, Molded-Case Switches, and Circuit-Breaker Enclosures |
+| NEMA FU 1 | Low Voltage Cartridge Fuses |
| NEMA 250 | Enclosures for Electrical Equipment (1000 Volts Maximum) |
+| NFPA 70 | National Electrical Code (Articles 110, 230, 240, 404, 422, 430, 440, 620, 625, 700, 701, and 702) |
+| NFPA 70E | Standard for Electrical Safety in the Workplace |
| OSHA 29 CFR 1910.147 | The Control of Hazardous Energy (Lockout/Tagout) |
−| NEMA FU 1 | Low Voltage Cartridge Fuses |
−| NETA ATS | Acceptance Testing Specifications for Electrical Power Equipment and Systems |
+| ANSI/NETA ATS | Standard for Acceptance Testing Specifications for Electrical Power Equipment and Systems |
+| ASCE 7 | Minimum Design Loads and Associated Criteria for Buildings and Other Structures (Chapter 13) |
+| ICC-ES AC156 | Acceptance Criteria for Seismic Certification by Shake-Table Testing of Nonstructural Components |
−## Where the contract documents, the adopted building code, or a referenced standard conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
+## UL 98 is the listing under which an enclosed safety switch receives its voltage, ampere, horsepower, and short-circuit ratings, and NEMA KS 1 is the construction and performance standard the heavy-duty class is built to; UL 489 performs the same role for an enclosed circuit breaker and a molded-case switch, and UL 508 for a manual motor controller. NFPA 70 decides where a disconnecting means is required and which of these products satisfies it at each location, which is why the listing standard and the code are both cited and neither replaces the other. {note}
−## UL 98 is the listing standard that establishes the switch's voltage, ampere, horsepower, and short-circuit ratings, while NFPA 70 governs where and how the switch is applied as a disconnecting means. {note}
−
−## NEMA KS 1 defines the heavy-duty and general-duty construction classes referenced throughout this standard and the corresponding endurance and performance requirements. {note}
−
# Submittals {toc}
## Action Submittals {toc}
−### The Contractor shall submit the following for the Engineer's review and approval prior to procurement:
+### The Contractor shall submit the following for review before any disconnect is released for manufacture:
−- Product data for each switch identifying the duty class (heavy-duty or general-duty), fusible or non-fusible construction, ampere rating, voltage rating, horsepower rating, number of poles, and neutral arrangement
−- The UL 98 listing and the marked short-circuit current rating, including the fuse class and maximum fuse ampere rating on which a fusible switch's SCCR depends
−- Catalog data confirming the enclosure NEMA 250 type and the enclosure listing to UL 50 or UL 50E for the installation environment
−- For service-entrance-rated switches, documentation of the UL 98 service-entrance listing and the neutral bonding and equipment grounding provisions
−- A schedule identifying every switch on the project, its tag, the equipment it serves, its location, and its ratings
−- Where a series rating is relied upon, documentation of the tested series combination identifying the upstream device type and rating
+- product data for each disconnect type, identifying the listing standard, the duty class, the fusible or non-fusible construction, the voltage, ampere, and horsepower ratings, the number of poles, the neutral arrangement, and the enclosure type and material
+- a disconnect schedule correlating each disconnect designation to the equipment or feeder it serves, its location, its voltage, its ampere and horsepower ratings, the fuse class and ampere rating where fusible, the enclosure type, and the accessories furnished
+- the short-circuit current rating of each disconnect, with the fuse class and maximum fuse rating, or the upstream overcurrent device type and rating, on which that rating depends
+- documentation of the service equipment listing for each disconnect the one-line diagram shows as service equipment
+- enclosure dimensions, mounting provisions, and conduit entry areas for each enclosure size furnished
+- wiring diagrams for each disconnect furnished with a shunt trip, an auxiliary contact, or an electrical interlock, showing the terminal designations and the circuit each device connects to
+- the nameplate schedule listing the text to appear on each disconnect nameplate
+- the seismic certification for the disconnect, where the datasheet requires one
```datasheet
−label: Action Submittals Required
+label: Action Submittals
type: checkbox
options:
− - "Product data (duty class, fusible/non-fusible, ratings, poles, neutral)"
− - "UL 98 listing and marked SCCR with fuse class basis"
− - "Enclosure NEMA type and UL 50 / UL 50E listing"
− - "Service-entrance listing and bonding/grounding provisions (where applicable)"
− - "Project switch schedule"
− - "Series rating documentation (where applicable)"
−default: "UL 98 listing and marked SCCR with fuse class basis"
+ - "Product data per disconnect type"
+ - "Disconnect schedule"
+ - "Short-circuit current rating and basis"
+ - "Service equipment listing documentation"
+ - "Enclosure dimensions and entry areas"
+ - "Accessory wiring diagrams"
+ - "Nameplate schedule"
+ - "Seismic certification"
+default:
+ - "Product data per disconnect type"
+ - "Disconnect schedule"
+ - "Short-circuit current rating and basis"
+ - "Nameplate schedule"
+constraint: all_of
```
−### Switch procurement shall not proceed until the corresponding submittals are reviewed and returned.
+### A disconnect shall not be released for manufacture until the action submittals covering it have been reviewed and returned.
−### The marked SCCR submitted for a fusible switch shall state the specific fuse class and maximum fuse ampere rating, because the assembly SCCR is established only with those fuses installed.
+### The short-circuit current rating is the submittal item that most often comes back wrong, because the rating printed in a catalog is the highest rating the switch holds with the most favorable fuse class installed, and the rating that applies is the one marked for the fuse class and maximum rating actually furnished, or for a non-fusible switch, the one marked for the overcurrent device actually ahead of it. {note}
−## Closeout Submittals {toc}
+## Informational Submittals {toc}
−### The Contractor shall provide the following at substantial completion before the switch work is accepted:
+### The Contractor shall submit the following with or before the action submittals:
−- As-built switch schedule reflecting installed locations, tags, ratings, and the equipment served
−- Operation and maintenance data covering fuse type and rating for each fusible switch, interlock defeat procedure, and recommended maintenance
−- Field test and torque records for line and load terminations
−- Warranty documentation
+- 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 short-circuit current rating table for each switch type, identifying the fuse class or the upstream device each rating depends on
+- the manufacturer's published derating factors applied for ambient temperature and altitude, where either exceeds the rating basis of the listing
```datasheet
−label: Required Closeout Submittals
+label: Informational Submittals
type: checkbox
options:
− - "As-built switch schedule"
− - "Operation and maintenance data (fuse data, interlock, maintenance)"
− - "Field test and termination torque records"
− - "Warranty documentation"
−default: ["As-built switch schedule", "Operation and maintenance data (fuse data, interlock, maintenance)", "Field test and termination torque records", "Warranty documentation"]
+ - "Manufacturer qualification statement"
+ - "Field testing firm and technician qualifications"
+ - "Published short-circuit current rating tables"
+ - "Ambient and altitude derating factors"
+default:
+ - "Manufacturer qualification statement"
+ - "Field testing firm and technician qualifications"
+ - "Published short-circuit current rating tables"
+constraint: all_of
```
−# Quality Assurance {toc}
+## Closeout Submittals {toc}
−## Listing and Labeling {toc}
+### The Contractor shall submit the following before the disconnects are accepted:
−### Every enclosed switch shall be listed and labeled to UL 98 by a Nationally Recognized Testing Laboratory.
+- the record disconnect schedule, reflecting the as-installed location, ratings, fuse class and rating, and accessories of every disconnect
+- the field acceptance test report for each disconnect, giving every measured value, the acceptance criterion applied, and the tester's determination
+- operation and maintenance data covering each disconnect type, the fuse class and rating installed in each fusible disconnect, the door interlock defeat procedure, and the inspection and maintenance intervals of NEMA KS 3
+- the arc-flash incident energy labels installed, with the study revision they were taken from
+- the warranty certificate identifying each disconnect and the warranty commencement date
+- a signed receipt from the Owner for the spare parts delivered
−### Each switch shall be marked with its voltage rating, ampere rating, horsepower rating, number of poles, and short-circuit current rating.
+```datasheet
+label: Closeout Submittals
+type: checkbox
+options:
+ - "Record disconnect schedule"
+ - "Field acceptance test reports"
+ - "Operation and maintenance data"
+ - "Arc-flash label record"
+ - "Warranty certificate"
+ - "Spare parts receipt"
+default:
+ - "Record disconnect schedule"
+ - "Field acceptance test reports"
+ - "Operation and maintenance data"
+ - "Warranty certificate"
+ - "Spare parts receipt"
+constraint: all_of
+```
−### A switch that is not listed to UL 98, or whose marking does not display the ratings required by this standard, shall not be installed.
+### The record schedule is the document the next electrician reads before replacing a fuse, and a fusible disconnect whose fuse class and rating are recorded nowhere but on the fuse itself loses that record the first time a fuse of another class is pressed into its clips. {note}
−### A horsepower rating is required for any switch applied as a motor disconnecting means, because NFPA 70 430.109 requires the disconnect to be horsepower-rated, not merely ampere-rated. {note}
+# Quality Assurance {toc}
## Manufacturer Qualifications {toc}
−### Switches shall be the product of a manufacturer regularly engaged in producing UL 98 listed enclosed switches.
+### Each disconnect shall be produced by a manufacturer that has held a listing for enclosed switches or enclosed circuit breakers of the type furnished for not less than the period indicated in the datasheet.
−### All switches of a given duty class on the project should be furnished by a single manufacturer so that fuse provisions, handle and interlock operation, and spare parts are consistent across the facility.
+```datasheet
+label: Manufacturer Listing History
+type: range
+unit: years
+options:
+ min: 0
+ max: 20
+ setpoints: [0, 3, 5, 10, 20]
+default: 5
+constraint: min
+```
−## Installer Qualifications {toc}
+### The manufacturer shall state in the qualification statement the period, measured from the date of manufacture, for which replacement fuse clips, handles, interlocks, and accessories for the switch platform will remain available.
−### Switch installation shall be performed by a licensed electrical contractor and journeyman-level electricians experienced in the installation of low-voltage disconnecting means.
+## Listing {toc}
−# Environmental and Service Conditions {toc}
+### Each safety switch shall be listed and labeled to UL 98 by a Nationally Recognized Testing Laboratory, with the voltage, ampere, horsepower, and short-circuit current ratings and the fuse class the short-circuit rating depends on marked on the enclosure.
−## A switch and its enclosure shall be suitable for the electrical system, ambient conditions, and physical environment at its point of installation.
+### Each enclosed circuit breaker and each molded-case switch shall be listed and labeled to UL 489 by a Nationally Recognized Testing Laboratory, in an enclosure listed for the breaker frame installed in it.
−## Installation Environment {toc}
+### Each manual motor controller applied as a disconnecting means shall be listed to UL 508 and marked "Suitable as Motor Disconnect" in accordance with NFPA 70 430.109(A)(6).
−### The installation environment shall determine the required enclosure NEMA 250 type.
+### Each disconnect the one-line diagram shows as service equipment shall be listed and marked as suitable for use as service equipment, and shall be installed and arranged as [[sync/electrical-service-entrance]] requires.
−```datasheet
−label: Installation Environment
−type: select
−options:
− - "Indoor, dry, climate-controlled"
− - "Indoor, damp or uncontrolled (unconditioned mechanical room)"
− - "Outdoor, exposed (rain, sleet, snow)"
− - "Wet location or washdown (hose-directed water)"
− - "Corrosive (coastal salt air, chemical exposure)"
− - "Industrial, dust and falling dirt (indoor, dust-tight)"
−default: "Indoor, dry, climate-controlled"
−```
+### The service equipment listing adds the provision for the main bonding jumper and the neutral termination to the product, and it is the product this standard governs; where the switch stands, how it is grouped with others, how it is marked, and whether it carries ground-fault protection of equipment are service rules that live elsewhere. {note}
−### Indoor dry installations may use a NEMA Type 1 enclosure.
+### A switch whose marking does not display the ratings this article requires shall not be installed.
−### Outdoor and damp locations shall use a NEMA Type 3R enclosure as a minimum.
+## Field Testing Firm {toc}
−### Wet and washdown locations shall use a NEMA Type 4 or Type 4X enclosure.
+### Field acceptance testing shall be performed by the firm indicated in the datasheet.
−### Corrosive locations shall use a NEMA Type 4X enclosure of stainless steel or nonmetallic construction.
+```datasheet
+label: Field Acceptance Testing Firm
+type: radio
+options:
+ - "Independent testing firm accredited to ANSI/NETA ATS"
+ - "Manufacturer's field service organization"
+ - "Installing contractor's own technicians"
+```
−### Industrial dust-tight indoor locations may use a NEMA Type 12 enclosure.
+### The technicians who perform field acceptance testing shall have tested enclosed switches of the type furnished and shall be qualified in accordance with [[sync/electrical-acceptance-testing]].
−### The detailed enclosure requirements for each environment are addressed in the Enclosure section. {note}
+### An independent firm has no stake in whether the disconnect passes and reports against a published acceptance standard; the manufacturer's organization knows the product best; the installing contractor's own technicians cost least and are available on the installer's schedule, and on a project whose disconnects are small equipment switches the installer's own test is the arrangement most Owners accept. Which of these the Owner wants depends on how the results will be used, on the size of the largest disconnect, and on whether a report from the party who installed the equipment would satisfy the Owner's insurer and the Authority Having Jurisdiction. {note}
+# Environmental and Service Conditions {toc}
+
## Ambient Temperature {toc}
+### Each disconnect shall carry its nameplate ratings at the design ambient temperature of the space indicated in the datasheet.
+
```datasheet
−label: Ambient Temperature (Maximum)
−type: select
+label: Indoor Design Ambient Temperature
+type: range
unit: °C
options:
− - "40°C (standard rating)"
− - "50°C (elevated indoor or mechanical room)"
− - "55°C (rooftop or process area, consult manufacturer)"
−default: "40°C (standard rating)"
+ min: 40
+ max: 55
+ setpoints: [40, 45, 50, 55]
+default: 40
+constraint: min
```
−### Switches installed in locations with sustained ambient temperatures above 40°C shall be derated or an oversized switch shall be specified per the manufacturer's published derating data.
+### UL 98 switches, UL 489 breakers, and UL 248 fuses carry their ratings at a 40 °C ambient, so a 40 °C design ambient is the condition at which the nameplate applies without correction; a higher value covers a mechanical room, a penthouse, or a process space whose temperature cannot be held at that ambient at design load, at the cost of a larger switch or a larger fuse for the same load, and a fuse in a hot enclosure opens at a lower current than its rating states. {note}
−### Rooftop-mounted switches serving air-conditioning equipment routinely see elevated ambient temperatures from solar gain and shall be rated accordingly.
+### Where a disconnect is installed outdoors, on a roof, or in a space that follows the outdoor temperature, and [[parameter: site-ambient-temperature-maximum]] exceeds 40 °C, the manufacturer shall derate the switch, the breaker, and the fuses in accordance with its published factors and shall state the derated ratings in the action submittals.
−# Duty Class {toc}
+### A rooftop disconnect in direct sun runs well above the air temperature around it, because the enclosure absorbs solar gain and the fuses add their own heat inside it, which is why the outdoor condition is judged at the site maximum rather than at the indoor design value. {note}
−## NEMA KS 1 defines two construction classes for enclosed switches, heavy-duty (HD) and general-duty (GD), differing in endurance, voltage rating, fault withstand, and available enclosure types. {note}
+## Altitude {toc}
−## Heavy-duty switches are rated to 600V and up to 1200A, accept current-limiting fuses for a high short-circuit current rating, and are available in the full range of enclosure types; general-duty switches are limited to 240V and 600A and to NEMA Type 1 and Type 3R enclosures. {note}
+### Each disconnect 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.
−## The switch duty class shall be specified for each application, selected to meet the required voltage, ampacity, short-circuit rating, and enclosure type.
+### Air thins with altitude, which reduces both the convective cooling that sets the continuous current rating of the switch and the dielectric strength of the clearances inside it, so a switch 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 Qualification {toc}
+
+### The seismic certification required for each disconnect shall be as indicated in the datasheet.
+
```datasheet
−label: Duty Class
−type: radio
+label: Seismic Certification Requirement
+type: select
+derived: "[[parameter: seismic-design-category]] and the component importance factor assigned to the disconnect under ASCE 7 Chapter 13"
options:
− - "Heavy-duty (HD) — to 600V, to 1200A"
− - "General-duty (GD) — to 240V, to 600A"
−default: "Heavy-duty (HD) — to 600V, to 1200A"
+ - "No seismic certification required"
+ - "Anchorage design only, in accordance with ASCE 7 Chapter 13"
+ - "Special certification of the disconnect as an active component in accordance with ASCE 7 Section 13.2.2"
+default: derived
```
−## Switches applied at 480V or 600V shall be heavy-duty, because general-duty switches are rated only to 240V.
+### Anchorage keeps the disconnect on its wall or stand; special certification demonstrates that the switch still operates after the design earthquake, which ASCE 7 requires of a component whose importance factor is above 1.0. A disconnect serving a fire pump, a smoke control fan, an elevator designated for fire service access, or another life-safety load carries an importance factor of 1.5 under ASCE 7, and so does one needed for the continued operation of a Risk Category IV facility. {note}
−## Switches applied as feeder or service disconnecting means shall be heavy-duty.
+### Where seismic certification is required, it shall be performed in accordance with the seismic provisions of [[parameter: adopted-building-code]] and ASCE 7 Chapter 13, by shake-table test in accordance with ICC-ES AC156 or by analysis accepted by the Authority Having Jurisdiction, and the certificate shall cover the disconnect as furnished, including its enclosure and accessories.
−## Switches subject to frequent operation, motor switching, or higher fault exposure shall be heavy-duty.
+# Disconnect Device {toc}
−## General-duty switches may be used only on 240V and below circuits with light operating duty and low available fault current, typically small commercial and residential service or branch applications. {note}
+## Device Family {toc}
−## Applying a general-duty switch where a heavy-duty switch is required is a frequent and consequential error, because the general-duty switch lacks the voltage rating, fault withstand, and endurance the application demands. {note}
+### The device family furnished for the disconnects on the project shall be as indicated in the datasheet.
−# Switch Function {toc}
+```datasheet
+label: Disconnect Device Family
+type: select
+options:
+ - "Safety switch listed to UL 98"
+ - "Enclosed circuit breaker or molded-case switch listed to UL 489"
+ - "Manual motor controller listed to UL 508 and marked suitable as motor disconnect"
+default: "Safety switch listed to UL 98"
+```
−## Fusible or Non-Fusible {toc}
+### A safety switch is the construction the large majority of stand-alone disconnects are built on, which is why the field defaults to it: its blades are visible through the open door, it is horsepower rated across the ampere range, and a fusible switch with current-limiting fuses reaches the highest short-circuit rating of the three in the smallest enclosure. An enclosed circuit breaker is reset rather than refused after a fault, accepts a shunt trip and an electronic trip unit, and matches the breaker family already in the Owner's panelboards, at the cost of a lower interrupting rating per dollar and no visible contact gap; a molded-case switch is the same frame without a thermal trip, for a disconnect that must isolate only. A manual motor controller marked suitable as motor disconnect is the smallest and least expensive of the three, and it is listed for the disconnect function only within the horsepower range of its marking. {note}
+### Where the one-line diagram or an equipment schedule designates a different device family for a particular disconnect, that designation shall govern for that disconnect.
+
+### A manual motor controller shall be applied as a disconnecting means only within the horsepower and voltage range of its "Suitable as Motor Disconnect" marking, and only on the load side of the branch-circuit protective device as NFPA 70 430.109(A)(6) requires.
+
+## Duty Class {toc}
+
+### Safety switches shall be of the duty class indicated in the datasheet.
+
```datasheet
−label: Switch Function
+label: Safety Switch Duty Class
type: radio
options:
− - "Fusible (switch with integral fuse provisions)"
− - "Non-fusible (disconnect only, no overcurrent device)"
−default: "Non-fusible (disconnect only, no overcurrent device)"
+ - "Heavy-duty"
+ - "General-duty"
+default: "Heavy-duty"
```
−### A fusible switch shall be provided where the switch is required to provide branch or feeder overcurrent protection in addition to disconnection.
+### NEMA KS 1 defines the heavy-duty switch, rated 600 V AC and 30 A through 1200 A, with a quick-make quick-break mechanism, visible blades, a padlockable handle, and a listing in every enclosure type, and it is the construction specified on nearly every commercial, institutional, and industrial project, which is why the field defaults to it. A general-duty switch is rated 240 V AC and 30 A through 600 A, is built to a lighter endurance and withstand level, is listed in Type 1 and Type 3R enclosures, and costs less, which is what makes it the switch of a dwelling service or a light 240 V load. {note}
−### A non-fusible switch may be provided where overcurrent protection is supplied by an upstream device and the switch is required only as a disconnecting or isolating means.
+### A general-duty switch shall not be applied on a system above 240 V AC, on a motor circuit above the horsepower of its marking, or where the available fault current exceeds its marked short-circuit current rating.
−### A non-fusible switch shall be applied only where the upstream overcurrent device protects the conductors and equipment served by the switch.
+### Heavy-duty switches shall be of visible-blade construction, so that the open position of every blade can be confirmed by direct observation with the door open.
−## Fuse Provisions {toc}
+## Overcurrent Provision {toc}
+### Whether the disconnect carries the overcurrent protection of the circuit it opens shall be as indicated in the datasheet.
+
```datasheet
−label: Fuse Class (fusible switches)
−type: select
+label: Overcurrent Protection in the Disconnect
+type: radio
options:
− - "Class R (rejection, RK1 or RK5)"
− - "Class J"
− - "Class T"
− - "Class L (above 600A)"
− - "Class H / K (basic, low SCCR)"
−default: "Class R (rejection, RK1 or RK5)"
+ - "Disconnect carries the circuit overcurrent protection"
+ - "Disconnect isolates only"
```
−### Fusible switches shall be furnished with fuse clips and rejection features matched to the specified fuse class.
+### A disconnect that carries the overcurrent protection is a fusible switch or a circuit breaker, and it is what a feeder tap, a transformer secondary, an elevator, and a piece of equipment whose nameplate calls for fuses at the disconnect each need; a disconnect that isolates only is a non-fusible switch or a molded-case switch, and it is what a motor or an air-conditioning unit whose branch circuit is already protected at the panelboard needs, at a lower cost and with no fuse to stock. Both are routine on the same project, and which one a given location needs follows from the one-line diagram and the nameplate of the equipment served, which is why the field carries no default. {note}
−### Fusible switches shall use current-limiting fuses of Class R, J, T, or L where a short-circuit current rating above 10kA is required.
+### Where the nameplate of the equipment served states that fuses are required, or states a maximum fuse size without naming a circuit breaker as an acceptable protective device, the disconnect serving it shall be a fusible switch regardless of the datasheet selection.
−### Class H and Class K fuses shall not be used where the available fault current exceeds 10kA, because a switch fused with non-current-limiting fuses is rated only 10kA SCCR.
+### Where the one-line diagram shows the overcurrent device at the disconnect, the disconnect shall be a fusible switch or a circuit breaker regardless of the datasheet selection.
−### Rejection-style fuse clips shall be provided so that a current-limiting fuse cannot be replaced with a non-current-limiting fuse of a lower class, which would void the marked short-circuit current rating.
+### A non-fusible switch or a molded-case switch shall be applied only where an overcurrent device on its supply side protects the conductors and the equipment it serves at the ampacity those conductors and that equipment require.
−### Class R, J, and T fuses are current-limiting and establish a switch SCCR of up to 200kA, while Class H and K fuses are not current-limiting and hold the switch to a 10kA SCCR; the fuse class is therefore a short-circuit decision, not only an overcurrent decision. {note}
+## Service Equipment Listing {toc}
−# Electrical Ratings {toc}
+### Whether a disconnect is furnished with the service equipment listing shall be as indicated in the datasheet.
−## Voltage Rating {toc}
+```datasheet
+label: Service Equipment Listing
+type: radio
+drawing_ref: "the one-line diagram"
+options:
+ - "Listed as suitable for use as service equipment"
+ - "Not service equipment"
+default: deferred
+```
+### A disconnect listed as service equipment shall be furnished with the neutral bonding provision and the equipment grounding terminal its listing includes, and the main bonding jumper shall be installed in accordance with [[sync/grounding-and-bonding]].
+
+### A disconnect that is not service equipment shall be furnished with its neutral, where one is present, insulated from the enclosure, and the bonding provision shall not be installed.
+
+# Ratings {toc}
+
+## Voltage and Frequency {toc}
+
+### The voltage rating of each disconnect shall be as indicated in the datasheet and shall equal or exceed the nominal voltage of the circuit it opens.
+
```datasheet
−label: System Voltage
+label: Voltage Rating
type: select
+drawing_ref: "the one-line diagram"
options:
− - "240V (1Φ or 3Φ)"
− - "480V, 3Φ"
− - "600V, 3Φ"
− - "208Y/120V, 3Φ 4-wire"
− - "480Y/277V, 3Φ 4-wire"
−default: "480V, 3Φ"
+ - "240 V AC"
+ - "480 V AC"
+ - "600 V AC"
+ - "125 V DC"
+ - "250 V DC"
+ - "600 V DC"
+default: deferred
```
−### The switch voltage rating shall equal or exceed the nominal system voltage of the circuit it disconnects.
+### A UL 98 switch is built in a 240 V AC class and a 600 V AC class, and the 600 V class serves every AC system from 208 V through 600 V; an enclosed circuit breaker is rated at the voltage of its frame, and a breaker rated 480 V is not a 600 V breaker. A DC rating is a separate rating a switch carries only where its listing includes one, and a switch applied on a DC circuit without a DC rating has no tested ability to interrupt the arc. {note}
−### A general-duty switch shall not be applied above 240V.
+### A disconnect with a slash voltage rating shall be applied only on a solidly grounded system whose line-to-ground voltage does not exceed the lower figure and whose line-to-line voltage does not exceed the higher figure of the rating, in accordance with NFPA 70 240.85, and a disconnect on a corner-grounded, impedance-grounded, or ungrounded system shall carry a straight voltage rating not less than the line-to-line voltage.
+### The rated frequency of the disconnects shall be as indicated in the datasheet.
+
+```datasheet
+label: Rated Frequency
+type: radio
+options:
+ - "60 Hz"
+ - "50 Hz"
+default: "60 Hz"
+```
+
## Ampere Rating {toc}
+### The ampere rating of each disconnect shall be as indicated in the datasheet.
+
```datasheet
−label: Switch Ampere Rating
−type: select
+label: Ampere Rating
+type: range
unit: A
−drawing_ref: "one-line diagram"
+drawing_ref: "the one-line diagram and the equipment schedules"
options:
− - "30 A"
− - "60 A"
− - "100 A"
− - "200 A"
− - "400 A"
− - "600 A"
− - "800 A"
− - "1200 A"
+ min: 30
+ max: 1200
+ setpoints: [30, 60, 100, 200, 400, 600, 800, 1200]
default: deferred
+constraint: exact
```
−### The switch ampere rating shall equal or exceed the continuous load it carries and shall not be less than the rating of the overcurrent device protecting the circuit.
+### Safety switches are built in the ampere frames the setpoints list, and the rating of each disconnect is fixed by the load it serves and the overcurrent device ahead of it, so it is read from the one-line diagram and the equipment schedules for each disconnect; the datasheet field records a rating only where one rating applies across the project, as on a project whose disconnects all serve identical units. {note}
−### Enclosed switches are manufactured in the standard ampere frames of 30, 60, 100, 200, 400, 600, 800, and 1200A; the selected switch shall be the standard frame that equals or exceeds the required ampacity. {note}
+### The ampere rating of a disconnect shall be not less than the rating of the overcurrent device ahead of it where the disconnect isolates only, and not less than the continuous load it carries where it also carries the overcurrent protection, with the fuse or trip rating sized to the circuit it protects in accordance with NFPA 70 Article 240.
−## Horsepower Rating {toc}
+### For an enclosed circuit breaker, the ampere rating indicated is the continuous current rating of the trip unit, and the breaker frame shall be one the manufacturer lists for that trip rating at the short-circuit current rating this standard requires.
−### A switch applied as a motor disconnecting means shall be horsepower-rated for the motor it serves, in accordance with NFPA 70 430.109.
+### A fusible switch shall accept the fuse ampere rating indicated on the one-line diagram or the equipment schedule without fuse reducers, and where a fuse smaller than the switch frame is indicated the switch shall be furnished with clips for the fuse size indicated or with reducers listed for the switch.
−### The switch horsepower rating at the applied voltage shall equal or exceed the rated horsepower of the motor.
+## Short-Circuit Current Rating {toc}
−### A horsepower-rated switch is tested to interrupt the locked-rotor current of a motor of that rating; an ampere-only rating does not establish that the switch can safely break motor starting and stalled-rotor currents. {note}
+### The short-circuit current rating marked on each disconnect, with the fuses or the overcurrent device on which it depends installed, shall equal or exceed the available fault current at its line terminals as established under [[sync/short-circuit-study]], and shall be not less than the rating indicated in the datasheet.
−## Motor Disconnect Sizing {toc}
+```datasheet
+label: Short-Circuit Current Rating
+type: range
+unit: kA
+drawing_ref: "the one-line diagram"
+options:
+ min: 10
+ max: 200
+ setpoints: [10, 14, 18, 22, 25, 30, 35, 42, 50, 65, 85, 100, 150, 200]
+default: deferred
+constraint: min
+```
−### The ampere rating of a switch serving a single motor shall be not less than 115 percent of the motor full-load current, in accordance with NFPA 70 430.110(A).
+### The datasheet value is a floor applied to every disconnect on the project; a disconnect whose line terminals see more fault current than that floor is rated for the fault current at its terminals. A single floor high enough to cover the worst location removes the per-disconnect tracking, at the cost of current-limiting fuses in switches that did not need them. {note}
−### The full-load current used for disconnect sizing shall be the value from the applicable NFPA 70 motor full-load current table, not the motor nameplate current.
+### A safety switch fused with Class H fuses, and a non-fusible switch ahead of a non-current-limiting device, carries a short-circuit current rating of 10 kA; the same switch fused with Class R, J, T, or L fuses carries a rating of up to 200 kA, because the current-limiting fuse clears the fault before the first peak and the switch never sees the full current. The fuse class is therefore a short-circuit decision before it is an overcurrent decision, and a non-fusible switch takes its rating from the specific overcurrent device ahead of it. {note}
−### Undersizing the motor disconnect to the nameplate current rather than to 115 percent of the table full-load current is a common code violation that an inspector will reject. {note}
+### The basis on which the short-circuit current rating of each disconnect is established shall be as indicated in the datasheet.
−## Short-Circuit Current Rating {toc}
+```datasheet
+label: Short-Circuit Current Rating Basis
+type: radio
+options:
+ - "Fully rated"
+ - "Series rated"
+default: "Fully rated"
+```
−### The short-circuit current rating (SCCR) of the switch, as marked and with the specified fuses installed for a fusible switch, shall equal or exceed the available fault current at its line terminals.
+### A fully rated disconnect carries a marked rating that stands on its own with the fuses or the device installed in it; a series-rated enclosed circuit breaker reaches its marked rating only in a tested combination with the specific upstream device it was tested with, which NFPA 70 240.86 permits where the combination is listed, so a later change to the panelboard breaker that feeds it can silently void the rating. Series rating lowers the cost of a breaker where the available fault current is high, and it is used where the upstream device is under the same Owner's control and is not expected to change. The marked rating of a non-fusible switch depends on the class and maximum rating of the upstream device the same way, but that dependency is the switch's own listing rather than a series rating under 240.86. {note}
+### Where series rating is the basis, the combination shall be one the manufacturer has tested and listed in accordance with NFPA 70 240.86(B), the upstream device on which the rating depends shall be identified in the action submittals, and the combination shall be field-marked in accordance with NFPA 70 110.22(C).
+
+### Where the disconnect serves a system that NFPA 70 Article 700, 701, or 708 requires to be selectively coordinated, a series-rated combination shall not be relied on within the coordinated path.
+
+## Poles and Neutral {toc}
+
+### The number of poles of each disconnect shall be as indicated in the datasheet.
+
```datasheet
−label: Short-Circuit Current Rating (SCCR)
+label: Number of Poles
type: select
−unit: kAIC
−drawing_ref: "one-line diagram"
+derived: "the number of ungrounded conductors of the circuit on the one-line diagram, plus one pole where the neutral arrangement selected under this standard is a switched neutral"
options:
− - "10 kAIC (non-current-limiting fuses or non-fusible, default duty)"
− - "100 kAIC (Class R, J, or T fuses)"
− - "200 kAIC (Class R, J, T, or L current-limiting fuses)"
−default: deferred
+ - "1-pole"
+ - "2-pole"
+ - "3-pole"
+ - "4-pole"
+default: derived
```
−### The available fault current shall be determined by the project short-circuit study and shall be confirmed for each switch location per [[sync/arc-flash-study]].
+### A disconnecting means opens every ungrounded conductor of the circuit at once, so the pole count follows from the system: two poles for a single-phase circuit, three for a three-phase circuit, and a fourth where the neutral is opened with them; a single-pole switch serves only a two-wire circuit with one ungrounded conductor. {note}
−### A non-fusible switch carries the SCCR established by its tested combination with a specific upstream overcurrent device, and that combination shall be verified for the available fault current at the switch.
+### Each disconnect shall simultaneously open every ungrounded conductor of the circuit it serves, in accordance with NFPA 70 230.74, 422.30, and 430.103 for the circuit type, with one pole for each ungrounded conductor and no pole in a grounded conductor other than a switched neutral furnished under this article.
−### A fusible switch with current-limiting Class R, J, or T fuses achieves an SCCR of up to 200kA, which is the principal reason a fusible switch is selected at locations with high available fault current. {note}
+### The neutral arrangement of each disconnect shall be as indicated in the datasheet.
−### An SCCR below the available fault current allows the switch to fail destructively during a fault rather than safely interrupting or withstanding it, and is both a code violation and a safety hazard. {note}
+```datasheet
+label: Neutral Arrangement
+type: select
+derived: "the presence of a grounded conductor in the circuit on the one-line diagram, and whether the one-line diagram shows that conductor opened together with the ungrounded conductors"
+options:
+ - "No neutral"
+ - "Solid neutral"
+ - "Switched neutral"
+default: derived
+```
−## Series Rating {toc}
+### A three-wire circuit has no neutral to carry and the switch needs no neutral provision; a four-wire circuit carries its neutral through the enclosure on a solid neutral assembly that is never opened; a switched neutral adds a pole that opens the neutral with the phases, which a transfer switch between two separately derived systems needs so that the neutral is bonded at one source at a time, and which a circuit bonded on both sides of the switch must not have, because opening the neutral of such a circuit leaves the ground path carrying the neutral current. {note}
−### Where a non-fusible or fusible switch relies on a tested series combination with an upstream overcurrent device to achieve its SCCR, the combination shall be a laboratory-tested and listed series combination per NFPA 70 240.86.
+### A solid neutral assembly shall be rated for the ampere rating of the switch and insulated from the enclosure, and the neutral conductor shall terminate on it rather than on the equipment grounding terminal.
−### Where a series combination is relied upon, the switch enclosure shall be field-marked to identify the series-rated combination and the required upstream device, in accordance with NFPA 70 110.22.
+### A switched neutral pole shall be furnished only where the one-line diagram shows the neutral opened at that disconnect, and the switched neutral pole shall open after and close before the ungrounded poles, or simultaneously with them, as the listing provides.
−### Substituting an upstream device that is not part of the tested series combination breaks the series rating and renders the installation noncompliant. {note}
+# Fuses {toc}
−# Poles and Neutral {toc}
+## Fuse Class {toc}
−## Number of Poles {toc}
+### Fusible disconnects shall be furnished with fuse clips of the class indicated in the datasheet and with fuses of that class installed.
```datasheet
−label: Number of Switched Poles
−type: radio
+label: Fuse Class
+type: select
options:
− - "2-pole (1Φ, or 2-wire)"
− - "3-pole (3Φ, 3-wire)"
− - "4-pole (3Φ with switched neutral)"
− - "6-pole (double-throw or special)"
−default: "3-pole (3Φ, 3-wire)"
+ - "Class J"
+ - "Class RK1"
+ - "Class RK5"
+ - "Class T"
+ - "Class L"
+ - "Class CC"
+ - "Class H"
```
−### The number of switched poles shall match the number of ungrounded conductors to be disconnected.
+### Class J fuses are current-limiting, rated through 600 A, and fit only Class J clips, so a fuse of a lower interrupting rating cannot be put in their place; Class RK1 and RK5 fuses share the Class H dimensions and depend on rejection clips to keep a Class H fuse out, with RK1 clearing a fault at a lower let-through than RK5 of the same rating, which is what raises the short-circuit rating of the switch and the protection of the load; Class T fuses are the most compact current-limiting class and are fast-acting only; Class L is the only class manufactured above 600 A; Class CC is a 30 A class with its own rejection feature, used in small switches and control circuits; Class H is the non-current-limiting class, rated to interrupt 10 kA, and is the class a 10 kA switch ships with. An Owner with a fuse stock already standardized on one class is the usual reason to pick that class, which is why the field carries no default. {note}
−### A switch used as a disconnecting means shall simultaneously open all ungrounded conductors of the circuit, in accordance with NFPA 70 404.
+### Where a disconnect rated above 600 A is fusible, it shall be furnished with Class L fuses and clips.
−## Neutral Arrangement {toc}
+### Class H fuses shall not be furnished where the available fault current at the disconnect exceeds 10 kA, because the Class H interrupting rating is 10 kA.
+### Where Class RK1 or Class RK5 fuses are selected, the switch shall be furnished with rejection-type fuse clips that accept only Class R fuses, in accordance with NFPA 70 240.60(B).
+
+### Where a fuse of a different class is indicated for a particular disconnect on the one-line diagram or an equipment schedule, that class shall govern for that disconnect, and the clips shall match it.
+
+### The fuse class installed in a switch shall be the class on which the marked short-circuit current rating of that switch was established.
+
+## Fuse Characteristic {toc}
+
+### Fuses in the classes manufactured in both constructions shall be of the characteristic indicated in the datasheet.
+
```datasheet
−label: Neutral Arrangement
+label: Fuse Time-Current Characteristic
type: radio
options:
− - "Solid neutral (bonded-through, not switched)"
− - "Switched neutral (4th switched pole)"
− - "No neutral (3-wire system)"
−default: "Solid neutral (bonded-through, not switched)"
+ - "Dual-element time-delay"
+ - "Fast-acting"
+default: "Dual-element time-delay"
```
−### A solid neutral assembly shall be provided where the system includes a grounded neutral conductor that is carried through the switch but not switched.
+### A dual-element time-delay fuse rides through a motor inrush or a transformer magnetizing current at a rating close to the full-load current, which is why it is the fuse installed in the great majority of disconnects and why the field defaults to it; a fast-acting fuse opens on the same inrush unless it is sized well above the running current, and then protects the conductors less closely, and it is used ahead of a load with no inrush where the fastest clearing matters. Class J, RK1, RK5, and CC are made in both constructions; Class T is fast-acting only, and Class L is made in time-delay and standard constructions under its own time-delay definition. {note}
−### A switched neutral (fourth switched pole) shall be provided where the neutral must be opened together with the ungrounded conductors, such as where the switch isolates a separately derived system or where required by the equipment served.
+### Where a fast-acting fuse is indicated for a particular disconnect on the one-line diagram or an equipment schedule, that characteristic shall govern for that disconnect.
−### Switching the neutral of a system that is bonded both upstream and downstream of the switch creates objectionable neutral current paths; the neutral shall be switched only where the application requires it.
+### Fuses shall be listed under the UL 248 series in the class and characteristic selected, shall be rated for the voltage of the circuit, and shall be of one manufacturer throughout the project.
−## Service-Entrance Rating {toc}
+### The fuse ampere rating of each fusible disconnect shall be as indicated on [[drawing: the one-line diagram and the equipment schedules]].
+### A fuse installed in a switch is sized to the conductor and the load it protects under NFPA 70 Article 240 and, for a motor or an air-conditioning unit, within the maximum the equipment nameplate or NFPA 70 Article 430 permits; the switch frame is then the smallest frame that accepts that fuse, which is why the fuse rating and the switch rating are two values on the schedule and not one. {note}
+
+## Fuse Clips and Pullers {toc}
+
+### Fuse clips shall be reinforced spring-pressure clips rated for the fuse class and ampere rating furnished, and Class L fuses shall be bolted to their mounting.
+
+### Each fusible switch shall be furnished with a fuse puller of the size the installed fuses require where the fuse class is not removable by hand with the switch open.
+
+# Enclosed Circuit Breakers and Molded-Case Switches {toc}
+
+## Where the device family selected or designated is an enclosed circuit breaker, the breaker shall be an inverse-time circuit breaker listed to UL 489 with a trip unit of the type indicated in the datasheet.
+
```datasheet
−label: Service-Entrance Rating
+label: Enclosed Circuit Breaker Trip Unit
type: radio
options:
− - "Not service entrance (feeder or equipment disconnect)"
− - "Service-entrance rated (with neutral bonding and grounding kit)"
−default: "Not service entrance (feeder or equipment disconnect)"
+ - "Thermal-magnetic"
+ - "Electronic"
+default: "Thermal-magnetic"
```
−### Where the switch serves as service disconnecting means, it shall be listed and labeled for use as service-entrance equipment per UL 98 and shall comply with NFPA 70 Article 230.
+## A thermal-magnetic trip unit has a fixed time-current characteristic and an instantaneous setting that is adjustable on the larger frames, and it is the construction the frames used as stand-alone disconnects are built with, which is why the field defaults to it; an electronic trip unit has adjustable long-time, short-time, and instantaneous settings, which is what selective coordination with the device upstream is set with, and a ground-fault function where the circuit needs one, and it is furnished on the larger frames and on any frame where the coordination study calls for it. {note}
−### A service-entrance-rated switch shall include a means to bond the grounded service conductor to the enclosure and an equipment grounding terminal, in accordance with NFPA 70 250.
+## Where an electronic trip unit is furnished, its settings shall be as established under [[sync/protective-coordination-study]], and the settings as commissioned shall be recorded in the closeout submittals.
−### The neutral bonding jumper of a service-entrance switch establishes the main bonding connection for the service; its omission leaves the service ungrounded and is a serious safety defect. {note}
+## A molded-case switch shall be a UL 489 breaker frame without a thermal trip element, marked with the maximum overcurrent device ahead of which it is listed, and it shall be applied only on the load side of an overcurrent device of that type and not exceeding that rating.
−### The Contractor shall coordinate the service neutral bond and grounding electrode connection at a service-entrance switch with [[sync/grounding-and-bonding]].
+## An enclosed circuit breaker or molded-case switch applied as a motor disconnecting means shall be a breaker or molded-case switch rated in amperes as NFPA 70 430.109(A)(2) or (A)(3) permits, and where the circuit breaker is an instantaneous-trip breaker it shall be applied only as part of a listed combination controller furnished under another standard.
−# Construction and Components {toc}
+## The enclosed breaker handle shall indicate the on, off, and tripped positions, shall be trip-free, and shall be operable with the enclosure door closed.
−## Enclosure {toc}
+# Double-Throw and Manual Transfer Switches {toc}
+## Where the one-line diagram shows a double-throw switch, the switch shall be of the construction indicated in the datasheet.
+
```datasheet
−label: Enclosure NEMA Type
−type: select
+label: Double-Throw Switch Construction
+type: radio
options:
− - "NEMA Type 1 (indoor, general purpose)"
− - "NEMA Type 3R (outdoor, rainproof)"
− - "NEMA Type 4 (watertight, indoor or outdoor)"
− - "NEMA Type 4X stainless steel (watertight, corrosion-resistant)"
− - "NEMA Type 4X nonmetallic (watertight, corrosion-resistant)"
− - "NEMA Type 12 (indoor, dust-tight)"
−default: "NEMA Type 1 (indoor, general purpose)"
+ - "Double-throw safety switch listed to UL 98"
+ - "Manual transfer switch listed to UL 1008"
```
−### The enclosure shall be listed to UL 50 and, for environmental types, UL 50E, and shall match the NEMA 250 type required by the installation environment.
+## A double-throw safety switch listed to UL 98 is a two-position switch with an off position between its throws, horsepower rated and available fusible or non-fusible, and it is the construction of a manual transfer for an optional standby load under NFPA 70 Article 702 and of a portable generator connection; a manual transfer switch listed to UL 1008 is transfer switch equipment with a withstand and closing rating and a listing for the system it transfers, which is what NFPA 70 700.5 and 701.5 require of the transfer equipment of an emergency or legally required standby system. The system the switch serves decides which listing is needed, which is why the field carries no default. {note}
−### The enclosure NEMA type shall be consistent with the installation environment selected in the Environmental and Service Conditions section.
+## A double-throw switch that transfers an emergency or legally required standby load shall be listed to UL 1008 as transfer switch equipment and shall be marked for the system it serves.
−### A NEMA Type 3R enclosure protects against falling rain, sleet, and ice but is not watertight; washdown and hose-directed-water locations require Type 4 or Type 4X. {note}
+## A double-throw switch shall be of break-before-make construction, so that the two sources cannot be connected together through the switch in any position, and its handle shall indicate which source is connected.
−### A NEMA Type 4X enclosure of Type 304 or Type 316 stainless steel, or of nonmetallic construction, shall be provided in coastal, food-processing, and chemical-exposure environments where a painted steel enclosure would corrode. {note}
+## Where a double-throw switch serves as the connection point for a portable generator, the switch shall be arranged so that the generator cannot be connected in parallel with the normal source, the connection cabinet and its inlet shall be listed for the purpose and installed as NFPA 70 702.12 requires, and the switch shall be marked with the source each throw connects.
−### Where the switch is mounted outdoors, conduit shall enter from the bottom or be provided with listed rain-tight hubs where it enters from the top, to prevent water migration into the enclosure.
+## A double-throw switch shall carry a horsepower rating for the largest motor it transfers, and its neutral arrangement shall follow the Poles and Neutral article of this standard.
−## Operating Mechanism and Visible Blade {toc}
+# Operating Mechanism and Accessories {toc}
−### The switch shall be operated by an external handle that indicates the ON and OFF position of the switch blades.
+## Handle and Lockout {toc}
−### The switch shall provide visible blade construction so that the open position of the blades can be confirmed by direct observation, where available for the ampere rating.
+### Each disconnect shall be operable from outside the closed enclosure by an external handle that indicates the open and closed positions in accordance with NFPA 70 404.7, with the handle movement and the position indication consistent across every disconnect on the project.
−### Visible-blade construction is commonly available through 400A and provides positive visual confirmation that the circuit is open before work begins; above 400A the open position is confirmed by the handle position indicator. {note}
+### Safety switch mechanisms shall be quick-make and quick-break, with the operating speed of the blades independent of the speed at which the handle is moved.
−### The operating handle shall be lockable in the OFF position to accept at least one padlock for lockout/tagout.
+### The operating handle shall be capable of being padlocked in the open position by not fewer than three padlocks, with the padlocking provision remaining in place whether or not a lock is installed, in accordance with NFPA 70 110.25 and OSHA 29 CFR 1910.147.
+### A padlock provision that must be added to the switch when it is needed does not satisfy NFPA 70 110.25, and a hasp that accepts one lock does not serve a group lockout under OSHA 29 CFR 1910.147, which is why three locks on a permanent provision is the construction required rather than a bare lockable handle. {note}
+
+### The handle shall not be capable of being padlocked in the closed position unless the disconnect serves a fire pump or another load NFPA 70 requires to be protected against unintended opening, in which case the handle shall accept a lock in the closed position and the provision shall be noted on the disconnect schedule.
+
+### Switch blades shall be connected so that they are de-energized when the switch is open, with the line conductors on the terminals the manufacturer designates as line, in accordance with NFPA 70 404.6.
+
+### A line-terminal shield shall be furnished on each switch rated 100 A and larger, and on each switch of any rating that is service equipment or that is fed from a source that remains energized when the switch is open, so that the line terminals are guarded when the door is open and the switch is off.
+
## Door Interlock {toc}
+### Each disconnect shall be furnished with a door interlock of the type indicated in the datasheet.
+
```datasheet
label: Door Interlock
type: radio
options:
− - "Defeatable (interlock can be bypassed by qualified person)"
− - "Non-defeatable (door cannot open with switch ON)"
−default: "Defeatable (interlock can be bypassed by qualified person)"
+ - "Defeatable with a tool"
+ - "Non-defeatable"
+default: "Defeatable with a tool"
```
−### The switch shall include a door interlock that prevents the enclosure door from opening while the switch is in the ON position.
+### A door interlock prevents the door from opening while the switch is closed and prevents the switch from closing while the door is open; a tool-defeatable interlock lets a qualified person open the door for inspection or testing with the switch energized, as NFPA 70E permits under an energized work permit, and it is the construction every listed switch is built with, which is why the field defaults to it; a non-defeatable interlock enforces de-energization before access and is furnished where unqualified persons operate the equipment or where the Owner's electrical safety program prohibits inspection under power. {note}
−### A defeatable interlock shall require a deliberate action by a qualified person to bypass and shall re-engage automatically when the door is closed.
+### A defeatable interlock shall require a deliberate action with a tool to bypass and shall re-engage automatically when the door is closed.
−### A defeatable interlock allows a qualified person to open the door for inspection with the switch energized, while a non-defeatable interlock enforces de-energization before access and is preferred where unqualified persons may operate the equipment. {note}
+## Accessories {toc}
−## Lockout/Tagout Provisions {toc}
+### Each disconnect shall be furnished with the accessories indicated in the datasheet, factory-installed and wired to terminal blocks where the accessory has a circuit.
−### The switch shall provide provisions for lockout/tagout in the OFF position in accordance with OSHA 29 CFR 1910.147.
+```datasheet
+label: Accessories
+type: checkbox
+options:
+ - "Auxiliary contact, one normally open and one normally closed"
+ - "Electrical interlock contact for the control circuit of the equipment served"
+ - "Shunt trip"
+ - "Viewing window in the door"
+ - "Equipment grounding terminal kit"
+ - "Enclosure space heater with thermostat"
+ - "Key interlock provision"
+constraint: all_of
+```
−### The lockout provision shall accept the number of padlocks required by the facility's energy-control program, with multiple-lock hasps provided where more than one worker must lock out the switch.
+### An auxiliary contact reports the switch position to a control system or opens the control circuit of the equipment served when the disconnect opens, which the control circuit of a packaged unit fed from a separate source needs; a shunt trip lets the disconnect be opened from a remote contact, as an elevator sprinkler shutdown or an emergency power off station requires, and it is available on an enclosed circuit breaker and on a shunt-trip safety switch built for it; a viewing window lets the blade position be confirmed without opening the door; a space heater holds the interior of an outdoor enclosure above the dew point through an idle period; a key interlock provision lets the disconnect take part in a key scheme with another device. Which accessories each disconnect needs follows from the equipment it serves, and the datasheet selection applies to every disconnect unless the schedule states otherwise. {note}
−### A line-side barrier or shield shall be provided where required so that the line terminals remain guarded when the door is open and the switch is OFF.
+### Where accessories for a particular disconnect are designated on the one-line diagram or an equipment schedule, those accessories shall be furnished on that disconnect in place of the datasheet selection.
−# HVAC and Equipment Disconnects {toc}
+### Where a shunt trip is furnished, its control voltage and the source of the trip signal shall be as indicated on [[drawing: the one-line diagram and the control diagrams]], and the trip circuit shall be tested through its initiating device before the disconnect is accepted.
−## A disconnecting means shall be installed within sight from, and readily accessible from, air-conditioning and refrigerating equipment, in accordance with NFPA 70 440.14. {note}
+### An auxiliary contact furnished to open the control circuit of the equipment served shall be an early-break contact that opens before the main contacts part.
−## The disconnect serving air-conditioning or refrigerating equipment shall not be mounted on a panel of the equipment that must be removed to service the equipment, per NFPA 70 440.14.
+### Where a space heater is furnished, it shall be supplied from the line side of the disconnect through its own fused tap, or from a separate source, so that it operates while the disconnect is open, and its source shall be identified at the disconnect as the Identification article requires.
−## The disconnect serving air-conditioning or refrigerating equipment shall meet the working space requirements of NFPA 70 110.26(A).
+## Conductor Terminations {toc}
+### Line and load terminals shall be of the lug type indicated in the datasheet.
+
```datasheet
−label: HVAC / Equipment Disconnect Type
+label: Line and Load Lug Type
type: radio
options:
− - "Non-fusible (overcurrent protection at upstream panel)"
− - "Fusible (overcurrent protection at the disconnect)"
−default: "Non-fusible (overcurrent protection at upstream panel)"
+ - "Mechanical set-screw lugs"
+ - "Compression lugs"
+default: manufacturer
```
−## The disconnect type for air-conditioning and refrigerating equipment shall be selected according to the equipment nameplate, which states whether fuses are required at the disconnect.
+### The manufacturer shall state the lug type furnished in the product data.
−## A rooftop equipment disconnect shall be provided in a NEMA Type 3R enclosure as a minimum, and in a Type 4X enclosure in coastal or corrosive environments. {note}
+### Mechanical lugs accept a range of conductor sizes and are the lugs a switch ships with; compression lugs are crimped to one conductor size with a tool matched to the lug, hold their pressure without re-torquing, and are furnished where the Owner's practice or the conductor material calls for them. {note}
−# Installation {toc}
+### Every lug shall be listed for the conductor material and the range of conductor sizes terminated in it, shall be rated for 75 °C conductors, and where aluminum conductors are terminated shall be listed for aluminum and marked AL9CU or AL7CU as the conductor temperature rating requires.
−## Location and Mounting {toc}
+### Each terminal shall carry one conductor unless the terminal is listed for more than one, and the switch shall be furnished with a lug kit or a wider enclosure where the conductor size or count indicated exceeds the capacity of the standard terminals.
−### Switch location and arrangement shall be [[drawing: as indicated on the equipment plans]].
+# Enclosure {toc}
−### Switches shall be mounted plumb, level, and secured to structural backing or to the equipment they serve.
+## Enclosure Type {toc}
−### A disconnecting means shall be located so that it is readily accessible and within sight of the equipment it controls where the applicable NFPA 70 article requires it.
+### The enclosure type shall be as indicated in the datasheet.
−### The operating handle, at its highest position, shall be not more than 6 ft 7 in. above the floor or working platform, in accordance with NFPA 70 404.8(A).
+```datasheet
+label: Enclosure Type per NEMA 250
+type: select
+options:
+ - "Type 1"
+ - "Type 3R"
+ - "Type 4"
+ - "Type 4X"
+ - "Type 12"
+ - "Type 7"
+ - "Type 9"
+```
−## Working Space {toc}
+### Disconnects stand wherever the equipment they serve stands, which on most projects is a mix of electrical rooms, mechanical rooms, rooftops, and exterior walls, so no single enclosure type is the norm across a project and the field carries no default. Type 1 is the construction for a dry, conditioned interior; Type 3R sheds falling rain and sleet and is the construction of a rooftop or exterior-wall disconnect that no hose reaches; Type 4 is watertight against hose-directed water and Type 4X is watertight and corrosion-resistant; Type 12 keeps dust, lint, and dripping oil out of an indoor industrial enclosure; Type 7 and Type 9 are the explosionproof and dust-ignitionproof constructions of a classified location. The type is selected for the worst condition the enclosure sees, and the clauses that follow require the higher type wherever the location calls for it. {note}
−### Minimum working space shall be maintained in front of each switch in accordance with NFPA 70 110.26.
+### The enclosure shall comply with UL 50 and, for a type other than Type 1, with UL 50E and NEMA 250 for the type selected, and the type shall be marked on the enclosure.
−### Working clearance shall be measured from the front of the enclosure or the front of any live parts, whichever is greater, to the nearest obstruction.
+### A disconnect installed outdoors, including on a roof, shall have an enclosure of Type 3R, Type 4, or Type 4X.
−### Working space in front of a disconnecting means shall not be used for storage.
+### A disconnect installed where it is subject to hose-directed water or wash-down shall have an enclosure of Type 4 or Type 4X.
−## Conductor Terminations {toc}
+### A disconnect installed where the atmosphere carries salt, chemical vapor, or another corrosive agent, including a coastal site, a wastewater facility, a chemical feed room, a cooling tower deck, and a food-processing area, shall have a Type 4X enclosure.
−### Line and load conductors shall be terminated in the switch lugs in accordance with [[sync/conductors-and-cables]] and the switch manufacturer's instructions.
+### A disconnect installed indoors where airborne dust, lint, or fibers accumulate, or where non-corrosive liquid drips or splashes, shall have an enclosure of Type 12, Type 4, or Type 4X.
−### Line conductors shall be connected to the line terminals and load conductors to the load terminals, so that the line side is de-energized only by the upstream device and the load side is de-energized by the switch.
+### A disconnect installed in a location classified under NFPA 70 Article 500 shall have an enclosure listed for the class, division, and group of that location as classified under [[sync/electrical-hazardous-locations]], Type 7 for a Class I location and Type 9 for a Class II location, and its operating handle and accessories shall be listed for the same classification.
−### All conductor terminations shall be torqued to the manufacturer's published torque values using a calibrated torque wrench.
+### Where a rating higher than the datasheet selection is required by the clauses of this article for the installed location, the higher rating shall be furnished and the conflict reported to the Engineer of Record before the disconnect is released for manufacture.
−### Termination torque values shall be recorded as part of the field test documentation.
+### A Type 3R enclosure shall be furnished with the drain openings its listing provides and shall be installed with those openings at the bottom and unobstructed.
−### Aluminum conductors shall be terminated only in lugs listed for aluminum and prepared per the lug manufacturer's instructions.
+## Enclosure Material {toc}
−## Fuse Installation {toc}
+### The enclosure material shall be as indicated in the datasheet.
−### Fuses shall be installed in fusible switches only after the switch is verified de-energized and the conductors terminated.
+```datasheet
+label: Enclosure Material
+type: select
+options:
+ - "Painted steel"
+ - "Type 304 stainless steel"
+ - "Type 316 stainless steel"
+ - "Non-metallic"
+default: "Painted steel"
+```
−### The installed fuse class and ampere rating shall match the fuse class on which the switch SCCR and the circuit overcurrent protection were based.
+### Painted steel serves every type other than Type 4X in a non-corrosive exposure and is the material the switches are built in, which is why the field defaults to it; stainless steel and non-metallic enclosures are what a Type 4X rating is built in, with Type 316 holding up where chlorides are present and a non-metallic enclosure holding up where the corrodent attacks stainless steel and where a non-conductive enclosure is wanted. {note}
−### A label identifying the required fuse class and maximum ampere rating shall be applied to or within each fusible switch.
+### Where the datasheet selects or a clause of this standard requires a Type 4X enclosure, the enclosure material shall be one for which the Type 4X rating is listed.
−# Testing {toc}
+### The finish of a painted steel enclosure shall be the manufacturer's standard finish system, and the manufacturer shall state the finish system and its color in the product data.
−## Factory Tests {toc}
+### A Type 1 enclosure shall be furnished with knockouts only where the manufacturer provides them, and a Type 3R, Type 4, Type 4X, Type 7, Type 9, or Type 12 enclosure shall be furnished with blank walls for field-made entries.
−### Each switch shall be production-tested by the manufacturer in accordance with UL 98 prior to shipment.
+## Conduit Entry {toc}
−### The Contractor shall furnish the manufacturer's certification that each switch passed its production tests on request.
+### Conduit and cable entries shall be made only through the areas the manufacturer designates, and an entry in a Type 3R, Type 4, Type 4X, Type 7, Type 9, or Type 12 enclosure shall use a hub or fitting listed to maintain the enclosure type.
−## Field Tests {toc}
+### An entry into an outdoor enclosure shall be made through the bottom or, where made through the top or a side, through a hub listed as raintight or wet-location rated for the enclosure type, and every unused opening shall be closed with a fitting listed for the type.
−### After installation and before energization, the Contractor shall perform a visual and mechanical inspection of each switch, including verification of ratings, enclosure type, interlock operation, and termination torque.
+### A raceway entering a Type 3R enclosure from above through a locknut and bushing rather than a hub is the path by which most outdoor switches fill with water, and the fault that follows is traced to the fitting rather than to the switch. {note}
−### The Contractor shall operate each switch through at least one open-close cycle to verify free mechanical operation and correct handle indication.
+# Disconnects at Served Equipment {toc}
−### The Contractor shall perform an insulation-resistance test on each pole of switches 400A and larger, phase-to-phase and phase-to-ground, in accordance with NETA ATS.
+## Motor Disconnects {toc}
+### A disconnect serving a motor shall be horsepower rated for the motor served as indicated on [[drawing: the motor and equipment schedules]], in accordance with NFPA 70 430.109, unless it is an enclosed circuit breaker or a molded-case switch applied under NFPA 70 430.109(A)(2) or (A)(3).
+
+### A horsepower-rated switch is tested to interrupt the locked-rotor current of a motor of that rating at that voltage, which an ampere rating alone does not demonstrate; the horsepower rating of a fusible switch is higher than that of the same switch non-fusible, because the fuses are credited with clearing the locked-rotor current, and both ratings appear on the nameplate. {note}
+
+### The ampere rating of a disconnect serving a motor shall be not less than 115 percent of the full-load current of the motor as read from the applicable table of NFPA 70 Article 430, in accordance with NFPA 70 430.110(A), and where the disconnect serves more than one motor or a motor with other loads its rating shall be determined in accordance with NFPA 70 430.110(C).
+
+### The disconnecting means at the motor that NFPA 70 430.102(B) requires shall be installed within sight of the motor and the driven machinery, unless the exception to 430.102(B) applies and the controller disconnect is lockable in accordance with NFPA 70 110.25.
+
+### The controller disconnect of a combination starter is furnished with the starter under its own standard, and the disconnect this article governs is the one at the motor, which is needed where the starter stands out of sight of the motor and the exception to 430.102(B) is not applied. {note}
+
+## Air-Conditioning and Refrigeration Equipment {toc}
+
+### A disconnect serving air-conditioning or refrigerating equipment shall be rated not less than 115 percent of the nameplate rated-load current or the branch-circuit selection current of the equipment, whichever is greater, and shall be horsepower rated for the equivalent horsepower determined in accordance with NFPA 70 440.12 unless it is an enclosed circuit breaker or a molded-case switch so permitted.
+
+### A disconnect serving air-conditioning or refrigerating equipment shall be installed within sight of and readily accessible from the equipment, in accordance with NFPA 70 440.14, and shall not be installed on a panel of the equipment that is designed to allow access to the equipment or that obscures the nameplate.
+
+### Where the disconnect is mounted on the equipment served, it shall be mounted at a location the equipment manufacturer permits, clear of the swing of every access panel and door and of every service clearance the manufacturer states, and where no such location exists it shall be mounted on a stand beside the equipment.
+
+### A rooftop unit nameplate states the minimum circuit ampacity and the maximum overcurrent protective device and names the device types it was listed with, and the disconnect is selected against that nameplate rather than against the compressor horsepower alone, which is why the equipment schedule carries the nameplate values and the disconnect is checked against the unit actually furnished. {note}
+
+### The Contractor shall confirm the nameplate rated-load current, the minimum circuit ampacity, and the maximum overcurrent protective device of each unit actually furnished against the disconnect and fuse ratings on the reviewed schedule before the disconnect is energized, and shall report any difference to the Engineer of Record.
+
+## Elevator Disconnects {toc}
+
+### The disconnecting means for each elevator, dumbwaiter, escalator, or moving walk shall be an enclosed, externally operable fused motor-circuit switch or an enclosed circuit breaker, in accordance with NFPA 70 620.51, and shall be installed within sight of the controller and at the location NFPA 70 620.51(C) requires for the equipment type.
+
+### Where main line power shutdown is furnished with the elevator for the sprinkler protection of its hoistway, machine room, machinery space, or control space, the elevator disconnect shall be an enclosed circuit breaker with a shunt trip, or a shunt-trip fused switch listed for the purpose, operated from the heat detection and control furnished with the elevator and fire alarm work, and no other provision shall be made to open or close the disconnect from another part of the premises, in accordance with NFPA 70 620.51(B).
+
+### Where the elevator is furnished with battery-powered rescue operation, a regenerative drive, or another source that can energize the controller with the disconnect open, the disconnect shall be furnished with an auxiliary contact wired to the controller as NFPA 70 620.51(B) and 620.91(C) require, and the disconnect shall be marked to identify that source.
+
+### A separate disconnecting means shall be furnished for the car lighting, receptacle, and ventilation circuit of each elevator, and for the car heating and air-conditioning circuit where one is furnished, located as NFPA 70 620.53 and 620.54 require.
+
+### Each elevator disconnect shall be marked with the elevator designation, the location of the supply-side overcurrent device, and, where the elevator has a separate source for its rescue operation or regenerative equipment, the location of that source.
+
+## Electric Vehicle Supply Equipment and Other Utilization Equipment {toc}
+
+### A disconnect serving electric vehicle supply equipment shall be furnished where NFPA 70 625.43 requires one, in an enclosure of the type the Enclosure article requires for its location, rated for the input of the unit, and installed within sight of the unit.
+
+### A disconnect serving an appliance or other utilization equipment shall be furnished where NFPA 70 422.31 requires one, shall be rated as that section requires, and shall be within sight of the equipment or lockable in the open position as that section permits.
+
+### A disconnect serving a transformer secondary, a feeder tap, or a tenant feeder shall be fusible or an enclosed circuit breaker, rated as NFPA 70 240.21 and 450.3 require for the conductors it protects, and located as those sections require.
+
+# Identification {toc}
+
+## Each disconnect shall carry a nameplate on the enclosure door, complying with [[sync/electrical-identification]] for material, lettering, and attachment, stating the disconnect designation, the equipment or feeder served, the voltage, the ampere rating, and the source panelboard or device and circuit that feed it.
+
+## The disconnect designation on the nameplate shall match the designation on the one-line diagram, the equipment schedule, and the equipment served.
+
+## Each fusible disconnect shall carry a label inside the door, or on the door where the enclosure has no inner cover, stating the fuse class, the fuse ampere rating, and the fuse characteristic installed, and stating that the short-circuit current rating of the switch depends on that fuse class.
+
+## Each disconnect that is service equipment shall be marked as the service disconnecting means and shall carry the available fault current and the date it was calculated, in accordance with NFPA 70 110.24.
+
+## Where a series-rated combination is the basis of the short-circuit current rating, the enclosure shall be field-marked to identify the combination and the replacement devices it depends on, in accordance with NFPA 70 110.22(C).
+
+## Arc-flash warning labels shall be applied to each disconnect in accordance with NFPA 70 110.16 and NFPA 70E, with the values taken from the study performed under [[sync/arc-flash-study]], and placed so that the label is read before the door is opened.
+
+## Where a disconnect, its control circuit, or its space heater is energized from more than one source, a marking identifying every source to be disconnected shall be applied at the disconnect.
+
+## Where a disconnect 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.
+
+# Testing {toc}
+
+## Factory Tests {toc}
+
+### The manufacturer shall perform the production tests of its listing on each disconnect before shipment, including a dielectric withstand test and a mechanical operation check of the switch and the door interlock, and shall furnish the results on request.
+
+## Field Acceptance Tests {toc}
+
+### Field acceptance testing shall be performed on each disconnect after installation is complete and before it 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 Test Scope
+label: Field Acceptance Tests
type: checkbox
options:
− - "Visual and mechanical inspection (ratings, enclosure, interlock)"
− - "Operational test (open-close cycle, handle indication)"
− - "Termination torque verification"
− - "Insulation-resistance test (400A and larger)"
−default: ["Visual and mechanical inspection (ratings, enclosure, interlock)", "Operational test (open-close cycle, handle indication)", "Termination torque verification"]
+ - "Visual and mechanical inspection including anchorage, nameplate, clearances, and enclosure type"
+ - "Operation through one open and close cycle with handle indication verified"
+ - "Door interlock and defeat operation"
+ - "Bolted connection torque verification against the manufacturer's values"
+ - "Insulation resistance of every disconnect, phase-to-phase and phase-to-ground"
+ - "Contact resistance across each pole"
+ - "Fuse class, rating, and characteristic verification against the reviewed schedule"
+ - "Shunt trip and auxiliary contact operation from the initiating device"
+ - "Line and load connection verification"
+default:
+ - "Visual and mechanical inspection including anchorage, nameplate, clearances, and enclosure type"
+ - "Operation through one open and close cycle with handle indication verified"
+ - "Door interlock and defeat operation"
+ - "Bolted connection torque verification against the manufacturer's values"
+ - "Fuse class, rating, and characteristic verification against the reviewed schedule"
+ - "Line and load connection verification"
+constraint: all_of
```
−### The Contractor shall correct any switch that fails inspection or test and shall re-verify.
+### Whether or not the datasheet selects the insulation resistance test for every disconnect, insulation resistance shall be measured on each disconnect rated 400 A and larger and on each disconnect that is service equipment, pole-to-pole and pole-to-ground with the switch closed and across each open pole with the switch open.
−# Identification and Labeling {toc}
+### Insulation resistance shall be measured for one minute at 500 V DC on a disconnect rated 250 V and below and at 1000 V DC on a disconnect rated above 250 V, and a reading below the minimum ANSI/NETA ATS states for the voltage class shall be investigated before the disconnect is energized.
−## Each switch shall be labeled to identify its tag, the equipment or circuit it serves, and the source of its supply, in accordance with [[sync/equipment-labeling]].
+### Where contact resistance is measured, a pole whose resistance deviates from the average of the poles of that switch by more than 50 percent shall be investigated and the switch corrected or replaced.
−## Each switch shall receive an arc-flash warning label in accordance with NFPA 70E prior to energization.
+### A disconnect 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 a fusible switch's fuse class is critical to its short-circuit rating, the required fuse class and maximum ampere rating shall be marked at the switch.
+# Installation {toc}
−## Where a series-rated combination is relied upon, the switch shall be field-marked to identify the series combination and the required upstream device per NFPA 70 110.22.
+## Placement and Working Space {toc}
+### Each disconnect shall be installed plumb and level, and secured to the structure, to a stand or strut frame that carries its weight without deflection, or to the equipment served where the Disconnects at Served Equipment article permits.
+
+### The center of the grip of the operating handle in its highest position shall be not more than 2.0 m (6 ft 7 in.) above the floor or working platform, in accordance with NFPA 70 404.8(A), and each disconnect shall be readily accessible.
+
+### Working space in front of each disconnect shall comply with NFPA 70 110.26 for the voltage of the circuit and the condition of the space, the door swing shall not reduce that space, and the space shall not be used for storage.
+
+### A disconnect installed outdoors on a stand shall be mounted with the bottom of the enclosure not less than 12 in. above finished grade or the roof surface, and a stand on a roof shall bear on the roof through a support the roofing system permits rather than through a penetration of the membrane.
+
+### Where seismic certification is required, each disconnect shall be anchored at the manufacturer's anchor points with anchors sized for the seismic loads applicable to the installation, in accordance with the certification.
+
+### A disconnect in an electrical room shall satisfy [[sync/electrical-rooms]], and a disconnect mounted on a housekeeping pad or a pad-mounted stand shall have the pad constructed under [[sync/concrete-pads]].
+
+## Wiring and Grounding {toc}
+
+### Conductors shall be sized and installed under [[sync/conductors-and-cables]], shall be terminated on the lugs furnished with the disconnect, and where field-furnished lugs are used they shall be listed for the conductor material and size and for the disconnect.
+
+### Every termination shall be torqued to the manufacturer's published value with a calibrated torque tool, and the value applied shall be recorded on the field test report.
+
+### Raceways serving the disconnect shall comply with [[sync/raceways-and-conduit]] and with the Conduit Entry article of this standard.
+
+### The enclosure shall be bonded to the equipment grounding conductor of the circuit in accordance with NFPA 70 Article 250 and [[sync/grounding-and-bonding]], and the equipment grounding conductor to the load shall be terminated on the grounding terminal furnished in the disconnect rather than under an enclosure screw.
+
+### Accessory and control conductors shall be landed on the terminal blocks furnished in the disconnect, labeled to match the conductor designations on the wiring diagrams, and routed within the enclosure clear of the blades and the fuses.
+
+## Fuse Installation and Energization {toc}
+
+### Fuses shall be installed only after the disconnect has been verified de-energized, the conductors have been terminated and torqued, and the fuse class, rating, and characteristic have been checked against the reviewed schedule, and the fuses installed shall be those on which the marked short-circuit current rating of the switch was established.
+
+### Before energization, the Contractor shall remove every shipping brace, blocking, and packaging material from the enclosure, shall confirm that the door interlock operates, and shall confirm that the line conductors are landed on the line terminals.
+
+### A fusible disconnect shall be energized with the fuses installed and the door closed, and the load shall be connected only after the field acceptance tests covering the disconnect have been completed and accepted.
+
# Delivery, Storage, and Handling {toc}
−## Switches shall be delivered in the manufacturer's original packaging with listing marks and ratings intact.
+## Each disconnect shall be delivered in the manufacturer's packaging with the listing marks and the nameplate intact, labeled with its disconnect designation, and shall be inspected for shipping damage at receipt.
−## Switches shall be stored indoors in a clean, dry location and protected from moisture, corrosive atmospheres, and physical damage until installed.
+## Disconnects shall be stored indoors in a clean, dry space where the temperature is held above the dew point, and where indoor storage is not available they shall be stored under cover, off the ground, and protected from condensation, precipitation, dust, and physical damage.
−## Switches shall be inspected for damage on delivery, and any damage shall be documented and reported before installation.
+## Fuses shall be stored in their original packaging in a dry location, segregated by class and rating, and shall not be stored loose inside an installed switch.
−## A switch whose enclosure, operating mechanism, or interlock shows evidence of impact or moisture intrusion shall not be installed.
+## Enclosures shall not be used as a support or a work surface during construction, and every opening shall remain sealed until the raceway or cable serving it is installed.
+## A disconnect damaged or wetted in transit, in storage, or in handling shall be repaired or replaced as the manufacturer directs and as the Engineer of Record accepts in writing.
+
# Warranty {toc}
+## The manufacturer shall warrant each disconnect, its mechanism, its interlock, and every factory-installed accessory against defects in materials and workmanship for the period indicated in the datasheet.
+
```datasheet
−label: Warranty Period
+label: Manufacturer's Warranty Period
+type: range
+unit: years
+options:
+ min: 1
+ max: 5
+ setpoints: [1, 2, 3, 5]
+constraint: min
+```
+
+## Where no warranty period is selected in the datasheet, the manufacturer's standard warranty period for the disconnect shall apply, and its term shall be stated in the product data.
+
+## The warranty period shall commence on the date indicated in the datasheet.
+
+```datasheet
+label: Warranty Commencement
type: select
options:
− - "1 year from substantial completion"
− - "2 years from substantial completion"
− - "5 years from substantial completion"
−default: "1 year from substantial completion"
+ - "Date of substantial completion"
+ - "Date of energization"
+ - "Date of shipment"
```
−## Switches shall be warranted by the manufacturer against defects in materials and workmanship for the specified period.
+## Warranty commencement at shipment is the manufacturer's usual term, and it consumes the warranty during storage and construction; commencement at energization or substantial completion moves the coverage to the period the Owner is operating the equipment, and the manufacturer prices the added months into the disconnect. {note}
−## The warranty period shall begin at the date of substantial completion, not the date of shipment or installation.
+## The warranty coverage scope shall be as indicated in the datasheet.
−## The Contractor shall warrant the installation, including terminations, interlock operation, and correct fuse selection, for the project warranty period.
+```datasheet
+label: Warranty Coverage Scope
+type: radio
+options:
+ - "Parts only"
+ - "Parts and labor"
+```
+## The Contractor shall warrant the installation, including every termination, the anchorage, the grounding, the fuse selection, and the field-installed accessories, for the project warranty period.
+
+## A disconnect or device 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.
+
+## A fuse that opens on a fault is not a warranty defect, and its replacement is a maintenance item unless the fuse opened because of a defect in the switch. {note}
+
# Spare Parts {toc}
+## The Contractor shall deliver to the Owner, before the disconnects are accepted, the number of spare fuse sets of each class, ampere rating, and characteristic installed indicated in the datasheet, where a set is one fuse per fused pole of the switches using that fuse.
+
```datasheet
−label: Spare Fuses (fusible switches)
−type: radio
+label: Spare Fuse Sets per Class and Rating
+type: range
+unit: sets
options:
− - "None"
− - "Three spare fuses of each class and rating installed"
− - "One spare set per fusible switch"
−default: "Three spare fuses of each class and rating installed"
+ min: 0
+ max: 3
+ step: 1
+default: 1
+constraint: min
```
−## Where fusible switches are installed, the Contractor shall provide spare fuses of the same class and ampere rating as those installed.
+## One spare set lets a cleared fuse be replaced the same day from the Owner's stock rather than from a supplier, which is why the field defaults to one; a facility with many switches on one fuse rating, or one whose supplier is distant, carries more. {note}
−## Spare fuses shall be stored in the electrical room in their original packaging and identified with the switch tag and rating they serve.
+## The Contractor shall deliver the additional spare parts indicated in the datasheet to the Owner before the disconnects are accepted, and shall obtain a signed receipt for them and for the spare fuses.
−## Stocking spare fuses allows a cleared fuse to be replaced promptly, restoring the disconnect to service without waiting on procurement. {note}
+```datasheet
+label: Additional Spare Parts
+type: checkbox
+options:
+ - "Fuse puller of each size installed"
+ - "Wall-mounted spare fuse cabinet in each electrical room"
+ - "One spare auxiliary contact kit of each type installed"
+ - "One spare shunt trip of each type installed"
+ - "One spare operating handle of each type installed"
+default:
+ - "Fuse puller of each size installed"
+constraint: all_of
+```
+
+## Spare fuses and parts shall be of the same manufacturer, class, and rating as the installed items, shall be delivered in their original packaging, and shall be labeled with the disconnect designation or the fuse rating they serve.
+
+## Spare fuses shall be stored in the spare fuse cabinet where one is furnished, or otherwise in a labeled container in the electrical room nearest the switches they serve, and shall not be stored inside an operating switch.