SYNC™

SynC · Editorial revision

Enclosed Switches and Disconnects

Revision5
EditedOct 19, 2026
StatusCurrent
Contents

View changes in this revision   Revision history

Current revision. This is editorial revision 5, the current text of this standard. Read it on the standard's page.

SynC Standards Team — Specifier (Platform Standards) ✓ OfficialDiscloses employment SynC (SynC Platform Team)
Remake batch 25 and its neighbor re-points, batch 24 where missing, and the adopted-electrical-code parameter: brought in line with the authoring repository

1 Scope

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. (1.1)
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. (1.2)
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. (1.3)
NOTE The following are governed elsewhere and are outside this standard: (1.4)
  • the panelboard that supplies the feeder or the branch conductors ahead of the disconnect, under PanelboardsPanelboardsResolves to the current adopted revision.sync/panelboards
  • switchboards, switchgear, and motor control centers, under Low Voltage SwitchboardsLow Voltage SwitchboardsResolves to the current adopted revision.sync/low-voltage-switchboards, Low Voltage SwitchgearLow Voltage SwitchgearResolves to the current adopted revision.sync/low-voltage-switchgear, and Motor Control CentersMotor Control CentersResolves to the current adopted revision.sync/motor-control-centers
  • the starter that packages a disconnect, a branch-circuit protective device, and a contactor in one listed enclosure, under Combination Motor StartersCombination and Manual Motor StartersResolves to the current adopted revision.sync/combination-motor-starters
  • the disconnect and bypass provisions built into a variable frequency drive, under HVAC Variable Frequency DrivesHVAC Variable Frequency DrivesResolves to the current adopted revision.sync/hvac-variable-frequency-drives and Low Voltage Variable Frequency DrivesLow-Voltage Variable Frequency DrivesResolves to the current adopted revision.sync/low-voltage-variable-frequency-drives
  • automatic transfer switches, under Automatic Transfer SwitchesAutomatic Transfer SwitchesResolves to the current adopted revision.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 Electrical Service EntranceElectrical Service EntranceResolves to the current adopted revision.sync/electrical-service-entrance
  • the DC disconnects, the rapid shutdown equipment, and the AC disconnect of a photovoltaic system, under Photovoltaic SystemsPhotovoltaic SystemsResolves to the current adopted revision.sync/photovoltaic-systems
  • the conductors that land in the disconnect and their terminations, under Conductors And CablesConductors and CablesResolves to the current adopted revision.sync/conductors-and-cables
  • the raceways entering the enclosure, under Raceways And ConduitRaceways and ConduitResolves to the current adopted revision.sync/raceways-and-conduit
  • the equipment grounding conductor, the bonding of the enclosure, and the main bonding jumper of a service, under Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current adopted revision.sync/grounding-and-bonding
  • the classification of a hazardous location and the wiring methods inside it, under Electrical Hazardous LocationsElectrical Installations in Hazardous (Classified) LocationsResolves to the current adopted revision.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 Short Circuit StudyShort-Circuit StudyResolves to the current adopted revision.sync/short-circuit-study, Protective Coordination StudyProtective Device Coordination StudyResolves to the current adopted revision.sync/protective-coordination-study, and Arc Flash StudyArc-Flash StudyResolves to the current adopted revision.sync/arc-flash-study
  • nameplate and label material, lettering, and attachment, under Equipment LabelingElectrical Equipment LabelsResolves to the current adopted revision.sync/equipment-labeling
1.5 The location of each disconnect shall be as indicated on the electrical plans.
1.6 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.

2 Referenced Standards

2.1 Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
2.2 Where the contract documents, the Authority Having Jurisdiction, or two referenced standards impose conflicting requirements, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
Standard Title
UL 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)
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
NOTE 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. (2.3)

3 Submittals

3.1 Action Submittals

3.1.1 The Contractor shall submit the following for review before any disconnect is released for manufacture:
  • 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
Action Submittalscheckbox
☑ 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
3.1.2 A disconnect shall not be released for manufacture until the action submittals covering it have been reviewed and returned.
NOTE 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. (3.1.3)

3.2 Informational Submittals

3.2.1 The Contractor shall submit the following with or before the action submittals:
  • the manufacturer's qualification statement required under Quality Assurance
  • the qualifications of the firm and the technicians who will perform field acceptance testing
  • the 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
Informational Submittalscheckbox
☑ Manufacturer qualification statement
☑ Field testing firm and technician qualifications
☑ Published short-circuit current rating tables
☐ Ambient and altitude derating factors

3.3 Closeout Submittals

3.3.1 The Contractor shall submit the following before the disconnects are accepted:
  • 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
Closeout Submittalscheckbox
☑ Record disconnect schedule
☑ Field acceptance test reports
☑ Operation and maintenance data
☐ Arc-flash label record
☑ Warranty certificate
☑ Spare parts receipt
NOTE 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. (3.3.2)

4 Quality Assurance

4.1 Manufacturer Qualifications

4.1.1 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.
Manufacturer Listing Historyrange
Not less than
years
351020
4.1.2 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.

4.2 Listing

4.2.1 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.
4.2.2 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.
4.2.3 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).
4.2.4 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 Electrical Service EntranceElectrical Service EntranceResolves to the current adopted revision.sync/electrical-service-entrance requires.
NOTE 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. (4.2.5)
4.2.6 A switch whose marking does not display the ratings this article requires shall not be installed.

4.3 Field Testing Firm

4.3.1 Field acceptance testing shall be performed by the firm indicated in the datasheet.
Field Acceptance Testing Firmradio
○ Independent testing firm accredited to ANSI/NETA ATS
○ Manufacturer's field service organization
○ Installing contractor's own technicians
4.3.2 The technicians who perform field acceptance testing shall have tested enclosed switches of the type furnished and shall be qualified in accordance with Electrical Acceptance TestingElectrical Acceptance TestingResolves to the current adopted revision.sync/electrical-acceptance-testing.
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. (4.3.3)

5 Environmental and Service Conditions

5.1 Ambient Temperature

5.1.1 Each disconnect shall carry its nameplate ratings at the design ambient temperature of the space indicated in the datasheet.
Indoor Design Ambient Temperaturerange
Not less than
°C
40455055
NOTE 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. (5.1.2)
5.1.3 Where a disconnect is installed outdoors, on a roof, or in a space that follows the outdoor temperature, and Site Ambient Temperature MaximumSite Ambient Temperature MaximumParameterEach project supplies its own value.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.
NOTE 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. (5.1.4)

5.2 Altitude

5.2.1 Each disconnect shall be derated for AltitudeAltitudeParameterEach project supplies its own value.altitude in accordance with the manufacturer's published correction factors where the altitude exceeds the 2000 m rating basis of the listing.
NOTE Air thins with altitude, which reduces both the convective cooling that sets the continuous current rating of the 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. (5.2.2)
5.2.3 Ambient temperature derating and altitude derating shall be applied cumulatively where both conditions apply.

5.3 Seismic Qualification

5.3.1 The seismic certification required for each disconnect shall be as indicated in the datasheet.
Seismic Certification Requirementselect
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
Derived — Seismic Design CategorySeismic Design CategoryParameterEach project supplies its own value.seismic-design-category and the component importance factor assigned to the disconnect under ASCE 7 Chapter 13 (by default)
NOTE 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. (5.3.2)
5.3.3 Where seismic certification is required, it shall be performed in accordance with the seismic provisions of Adopted Building CodeAdopted Building CodeParameterEach project supplies its own value.adopted-building-code and ASCE 7 Chapter 13, 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.

6 Disconnect Device

6.1 Device Family

6.1.1 The device family furnished for the disconnects on the project shall be as indicated in the datasheet.
Disconnect Device Familyselect
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
NOTE 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. (6.1.2)
6.1.3 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.
6.1.4 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.

6.2 Duty Class

6.2.1 Safety switches shall be of the duty class indicated in the datasheet.
Safety Switch Duty Classradio
● Heavy-duty
○ General-duty
NOTE 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. (6.2.2)
6.2.3 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.
6.2.4 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.

6.3 Overcurrent Provision

6.3.1 Whether the disconnect carries the overcurrent protection of the circuit it opens shall be as indicated in the datasheet.
Overcurrent Protection in the Disconnectradio
○ Disconnect carries the circuit overcurrent protection
○ Disconnect isolates only
NOTE 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. (6.3.2)
6.3.3 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.
6.3.4 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.
6.3.5 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.

6.4 Service Equipment Listing

6.4.1 Whether a disconnect is furnished with the service equipment listing shall be as indicated in the datasheet.
Service Equipment Listingradio
○ Listed as suitable for use as service equipment
○ Not service equipment
Per drawings — the one-line diagram (deferred by default)
6.4.2 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 Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current adopted revision.sync/grounding-and-bonding.
6.4.3 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.

7 Ratings

7.1 Voltage and Frequency

7.1.1 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.
Voltage Ratingselect
240 V AC
480 V AC
600 V AC
125 V DC
250 V DC
600 V DC
Per drawings — the one-line diagram (deferred by default)
NOTE 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. (7.1.2)
7.1.3 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.
7.1.4 The rated frequency of the disconnects shall be as indicated in the datasheet.
Rated Frequencyradio
● 60 Hz
○ 50 Hz

7.2 Ampere Rating

7.2.1 The ampere rating of each disconnect shall be as indicated in the datasheet.
Ampere Ratingrange
A
30601002004006008001200
Per drawings — the one-line diagram and the equipment schedules (deferred by default)
NOTE 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. (7.2.2)
7.2.3 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.
7.2.4 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.
7.2.5 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.

7.3 Short-Circuit Current Rating

7.3.1 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 Short Circuit StudyShort-Circuit StudyResolves to the current adopted revision.sync/short-circuit-study, and shall be not less than the rating indicated in the datasheet.
Short-Circuit Current Ratingrange
Not less than
kA
1014182225303542506585100150200
Per drawings — the one-line diagram (deferred by default)
NOTE 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. (7.3.2)
NOTE 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. (7.3.3)
7.3.4 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 Basisradio
● Fully rated
○ Series rated
NOTE 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. (7.3.5)
7.3.6 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).
7.3.7 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.

7.4 Poles and Neutral

7.4.1 The number of poles of each disconnect shall be as indicated in the datasheet.
Number of Polesselect
1-pole
2-pole
3-pole
4-pole
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 (by default)
NOTE 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. (7.4.2)
7.4.3 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.
7.4.4 The neutral arrangement of each disconnect shall be as indicated in the datasheet.
Neutral Arrangementselect
No neutral
Solid neutral
Switched neutral
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 (by default)
NOTE 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. (7.4.5)
7.4.6 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.
7.4.7 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.

8 Fuses

8.1 Fuse Class

8.1.1 Fusible disconnects shall be furnished with fuse clips of the class indicated in the datasheet and with fuses of that class installed.
Fuse Classselect
Class J
Class RK1
Class RK5
Class T
Class L
Class CC
Class H
NOTE 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. (8.1.2)
8.1.3 Where a disconnect rated above 600 A is fusible, it shall be furnished with Class L fuses and clips.
8.1.4 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.
8.1.5 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).
8.1.6 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.
8.1.7 The fuse class installed in a switch shall be the class on which the marked short-circuit current rating of that switch was established.

8.2 Fuse Characteristic

8.2.1 Fuses in the classes manufactured in both constructions shall be of the characteristic indicated in the datasheet.
Fuse Time-Current Characteristicradio
● Dual-element time-delay
○ Fast-acting
NOTE 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. (8.2.2)
8.2.3 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.
8.2.4 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.
8.2.5 The fuse ampere rating of each fusible disconnect shall be as indicated on the one-line diagram and the equipment schedules.
NOTE 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. (8.2.6)

8.3 Fuse Clips and Pullers

8.3.1 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.
8.3.2 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.

9 Enclosed Circuit Breakers and Molded-Case Switches

9.1 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.
Enclosed Circuit Breaker Trip Unitradio
● Thermal-magnetic
○ Electronic
NOTE 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. (9.2)
9.3 Where an electronic trip unit is furnished, its settings shall be as established under Protective Coordination StudyProtective Device Coordination StudyResolves to the current adopted revision.sync/protective-coordination-study, and the settings as commissioned shall be recorded in the closeout submittals.
9.4 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.
9.5 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.
9.6 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.

10 Double-Throw and Manual Transfer Switches

10.1 Where the one-line diagram shows a double-throw switch, the switch shall be of the construction indicated in the datasheet.
Double-Throw Switch Constructionradio
○ Double-throw safety switch listed to UL 98
○ Manual transfer switch listed to UL 1008
NOTE 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. (10.2)
10.3 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.
10.4 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.
10.5 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.
10.6 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.

11 Operating Mechanism and Accessories

11.1 Handle and Lockout

11.1.1 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.
11.1.2 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.
11.1.3 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.
NOTE 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. (11.1.4)
11.1.5 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.
11.1.6 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.
11.1.7 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.

11.2 Door Interlock

11.2.1 Each disconnect shall be furnished with a door interlock of the type indicated in the datasheet.
Door Interlockradio
● Defeatable with a tool
○ Non-defeatable
NOTE 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. (11.2.2)
11.2.3 A defeatable interlock shall require a deliberate action with a tool to bypass and shall re-engage automatically when the door is closed.

11.3 Accessories

11.3.1 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.
Accessoriescheckbox
☐ 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
NOTE 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. (11.3.2)
11.3.3 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.
11.3.4 Where a shunt trip is furnished, its control voltage and the source of the trip signal shall be as indicated on the one-line diagram and the control diagrams, and the trip circuit shall be tested through its initiating device before the disconnect is accepted.
11.3.5 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.
11.3.6 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.

11.4 Conductor Terminations

11.4.1 Line and load terminals shall be of the lug type indicated in the datasheet.
Line and Load Lug Typeradio
○ Mechanical set-screw lugs
○ Compression lugs
Manufacturer's standard (by default)
11.4.2 The manufacturer shall state the lug type furnished in the product data.
NOTE Mechanical lugs accept a range of conductor sizes and are the lugs 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. (11.4.3)
11.4.4 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.
11.4.5 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.

12 Enclosure

12.1 Enclosure Type

12.1.1 The enclosure type shall be as indicated in the datasheet.
Enclosure Type per NEMA 250select
Type 1
Type 3R
Type 4
Type 4X
Type 12
Type 7
Type 9
NOTE 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. (12.1.2)
12.1.3 The enclosure shall comply with UL 50 and, for a type other than Type 1, with UL 50E and NEMA 250 for the type selected, and the type shall be marked on the enclosure.
12.1.4 A disconnect installed outdoors, including on a roof, shall have an enclosure of Type 3R, Type 4, or Type 4X.
12.1.5 A disconnect installed where it is subject to hose-directed water or wash-down shall have an enclosure of Type 4 or Type 4X.
12.1.6 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.
12.1.7 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.
12.1.8 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 Electrical Hazardous LocationsElectrical Installations in Hazardous (Classified) LocationsResolves to the current adopted revision.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.
12.1.9 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.
12.1.10 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.

12.2 Enclosure Material

12.2.1 The enclosure material shall be as indicated in the datasheet.
Enclosure Materialselect
Painted steel
Type 304 stainless steel
Type 316 stainless steel
Non-metallic
NOTE 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. (12.2.2)
12.2.3 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.
12.2.4 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.
12.2.5 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.

12.3 Conduit Entry

12.3.1 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.
12.3.2 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.
NOTE 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. (12.3.3)

13 Disconnects at Served Equipment

13.1 Motor Disconnects

13.1.1 A disconnect serving a motor shall be horsepower rated for the motor served as indicated on 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).
NOTE 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. (13.1.2)
13.1.3 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).
13.1.4 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.
NOTE 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. (13.1.5)

13.2 Air-Conditioning and Refrigeration Equipment

13.2.1 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.
13.2.2 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.
13.2.3 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.
NOTE 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. (13.2.4)
13.2.5 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.

13.3 Elevator Disconnects

13.3.1 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.
13.3.2 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).
13.3.3 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.
13.3.4 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.
13.3.5 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.

13.4 Electric Vehicle Supply Equipment and Other Utilization Equipment

13.4.1 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.
13.4.2 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.
13.4.3 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.

14 Identification

14.1 Each disconnect shall carry a nameplate on the enclosure door, complying with Equipment LabelingElectrical Equipment LabelsResolves to the current adopted revision.sync/equipment-labeling 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.
14.2 The disconnect designation on the nameplate shall match the designation on the one-line diagram, the equipment schedule, and the equipment served.
14.3 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.
14.4 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.
14.5 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).
14.6 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 Arc Flash StudyArc-Flash StudyResolves to the current adopted revision.sync/arc-flash-study, and placed so that the label is read before the door is opened.
14.7 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.
14.8 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.

15 Testing

15.1 Factory Tests

15.1.1 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.

15.2 Field Acceptance Tests

15.2.1 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 Electrical Acceptance TestingElectrical Acceptance TestingResolves to the current adopted revision.sync/electrical-acceptance-testing, and shall include the tests indicated in the datasheet.
Field Acceptance Testscheckbox
☑ 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
15.2.2 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.
15.2.3 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.
15.2.4 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.
15.2.5 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.

16 Installation

16.1 Placement and Working Space

16.1.1 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.
16.1.2 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.
16.1.3 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.
16.1.4 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.
16.1.5 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.
16.1.6 A disconnect in an electrical room shall satisfy Electrical RoomsElectrical RoomsResolves to the current adopted revision.sync/electrical-rooms, and a disconnect mounted on a housekeeping pad or a pad-mounted stand shall have the pad constructed under Concrete PadsConcrete Equipment PadsResolves to the current adopted revision.sync/concrete-pads.

16.2 Wiring and Grounding

16.2.1 Conductors shall be sized and installed under Conductors And CablesConductors and CablesResolves to the current adopted revision.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.
16.2.2 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.
16.2.3 Raceways serving the disconnect shall comply with Raceways And ConduitRaceways and ConduitResolves to the current adopted revision.sync/raceways-and-conduit and with the Conduit Entry article of this standard.
16.2.4 The enclosure shall be bonded to the equipment grounding conductor of the circuit in accordance with NFPA 70 Article 250 and Grounding And BondingGrounding and Bonding for Electrical SystemsResolves to the current adopted revision.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.
16.2.5 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.

16.3 Fuse Installation and Energization

16.3.1 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.
16.3.2 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.
16.3.3 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.

17 Delivery, Storage, and Handling

17.1 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.
17.2 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.
17.3 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.
17.4 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.
17.5 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.

18 Warranty

18.1 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.
Manufacturer's Warranty Periodrange
Not less than
years
1235
18.2 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.
18.3 The warranty period shall commence on the date indicated in the datasheet.
Warranty Commencementselect
Date of substantial completion
Date of energization
Date of shipment
NOTE Warranty commencement at shipment is the manufacturer's usual term, and it consumes the warranty during storage and construction; commencement at energization or substantial completion moves the coverage to the period the Owner is operating the equipment, and the manufacturer prices the added months into the disconnect. (18.4)
18.5 The warranty coverage scope shall be as indicated in the datasheet.
Warranty Coverage Scoperadio
○ Parts only
○ Parts and labor
18.6 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.
18.7 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.
NOTE 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. (18.8)

19 Spare Parts

19.1 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.
Spare Fuse Sets per Class and Ratingrange
Not less than
sets
03
Default: 1 sets
NOTE 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. (19.2)
19.3 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.
Additional Spare Partscheckbox
☑ 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
19.4 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.
19.5 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.

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