Service and Feeder Conductors
Remake batch 26: rewritten from scratch under the authoring cheatsheet with datasheet constraints; neighbors re-pointed to the new scope boundaries; the electrical code is now the adopted-electrical-code project fact
Showing changes from Rev 2
to Rev 3
in Service and Feeder Conductors.
---
title: Service and Feeder Conductors
category: Electrical / Power Distribution Equipment
−toc_depth: 3
description: >
− When to use: Specifying service conductors (from the utility service point to the
− service equipment) and feeder conductors (from service equipment or a subpanel to
− branch-circuit overcurrent devices) on commercial, industrial, and institutional
− projects, for low-voltage systems (600 V and below) in raceways or as listed cable
− assemblies, including new and retrofit work. Covers material selection (copper vs.
− aluminum), insulation type, ampacity sizing, temperature-rating coordination,
− overcurrent coordination, parallel assemblies, splices and taps, connectors and
− lugs, and acceptance testing.
− Not intended for: Branch-circuit and specialty wiring (motor, control) — see
− sync/conductors-and-cables; metering and overhead service drops — see
− sync/electrical-service-entrance; raceways that house these conductors — see
− sync/raceways-and-conduit; grounding electrode, equipment grounding, and bonding
− conductors — see sync/grounding-and-bonding; panelboard bus sizing and breaker
− coordination beyond the lugs — see sync/panelboards; medium-voltage (above 600 V)
− feeders and telecommunications cabling — see sync/telecommunications-rooms-and-pathways.
+ When to use: The service conductors of a building or structure at 1000 V and below, from the service point to the service disconnecting means, complete: the conductor or cable product, its material, its sizing to the calculated load under NFPA 70 Articles 220 and 230, its termination temperature basis, its line-side splices and terminations, and its acceptance tests; and the application rules that apply to feeders over and above the conductor product: feeder sizing to the calculated load under NFPA 70 Articles 215 and 220, feeder protection at the conductor ampacity, parallel conductor sets and their raceway arrangement, the sizing of the feeder neutral for nonlinear load, the feeder voltage-drop criterion, feeder taps and transformer secondary conductors under NFPA 70 240.21, feeders to a separate structure and to a crane runway disconnect, and the acceptance tests a feeder receives beyond those of the conductor product. Applies to commercial, institutional, industrial, and water and wastewater facilities, new services and feeders and the upgrade of existing ones.
+ Not intended for: the conductor and cable product for feeders and branch circuits, its material selection, insulation type, stranding, color coding, ampacity correction and adjustment, splice and termination hardware, pulling, and insulation resistance testing ([[sync/conductors-and-cables]]); branch circuits of every kind ([[sync/conductors-and-cables]]); the service arrangement, the utility coordination, the drop and the lateral, the metering, the disconnecting means, and the NFPA 70 Article 230 routing rules for the run, including its length inside the building, its seals, its protection from damage, and its clearances ([[sync/electrical-service-entrance]]); cable rated above 1000 V ([[sync/medium-voltage-cables]]); busway used as a service or a feeder ([[sync/busway]]); the raceway as a product and its supports ([[sync/raceways-and-conduit]]); the concrete-encased duct bank ([[sync/underground-ductbank]]) and the manholes and handholes along it ([[sync/utility-manholes-and-handholes]]); the grounding electrode conductor, the main bonding jumper, and the equipment grounding conductor of every feeder ([[sync/grounding-and-bonding]]); the lugs and terminals the service equipment, the switchboard, the switchgear, and the panelboard furnish ([[sync/low-voltage-switchboards]], [[sync/low-voltage-switchgear]], [[sync/panelboards]]); the testing organization, its instruments, and the compiled report ([[sync/electrical-acceptance-testing]]); the studies that establish the available fault current and the device settings ([[sync/short-circuit-study]], [[sync/protective-coordination-study]]); and the label stock and lettering of field markings ([[sync/electrical-identification]]).
---
# Scope {toc}
−## This standard governs the materials, sizing, terminations, and field testing of service and feeder conductors rated 600 V and below for commercial, industrial, and institutional construction. {note}
+## This standard governs two things. First, the service conductors complete, because no other standard carries them: the conductor or cable that runs from the service point to the service disconnecting means, its material, its size, the temperature basis it is sized on, the splices and terminations made on its line side, and the tests that release it for connection. Second, the rules that apply to a feeder because it is a feeder: how it is sized to the load it carries, how it is protected, how a parallel set is arranged, how its neutral is sized, how much voltage it is allowed to lose, where it is tapped, and what is measured on it after energization. {note}
−## Service conductors are the conductors between the utility service point and the service equipment; feeder conductors are all conductors between the service equipment (or a subpanel) and the final branch-circuit overcurrent devices. {note}
+## The conductor as a product is specified once, under [[sync/conductors-and-cables]]. That standard carries the material selection for feeders and branch circuits, the insulation types, the stranding, the color coding, the ampacity correction and adjustment factors, the connector and splice hardware, the pulling limits, and the insulation resistance test of building wire. This standard is a layer over it: a feeder is built of the conductor product selected there and applied as this standard requires, and nothing in that standard is restated here. The service conductors are the exception, because [[sync/conductors-and-cables]] excludes them, so their product, sizing, terminations, and tests are carried here in full. {note}
−## The conductors covered here are installed in raceways or supplied as listed cable assemblies (for example metal-clad cable), in both new construction and in retrofit or expansion of existing service and feeder infrastructure. {note}
+## Service conductors run from the service point to the service disconnecting means and have no overcurrent protection on the premises side; the serving utility's protection is the only thing that clears a fault on them. Feeders run from the service equipment, a separately derived system, or another feeder's overcurrent device to the final branch circuit overcurrent device, and each is protected at its supply end. The difference in protection is why the service conductors are sized and routed under rules of their own and why the feeder rules of this standard rest on the overcurrent device at the feeder's source. {note}
−## Conductors for branch circuits and specialty wiring, including motor and control circuits, are outside this standard and are governed by [[sync/conductors-and-cables]]. {note}
+## The following are governed elsewhere and are outside this standard: {note}
−## Metering, utility service equipment enclosures, and overhead service drops are governed by [[sync/electrical-service-entrance]]. {note}
+- the conductor and cable product for feeders and branch circuits, including the feeder conductor material selection, the insulation type, the stranding, the color coding, the ampacity correction and adjustment factors, the connector and splice hardware, the aluminum termination practice, the pulling limits, and the insulation resistance test of building wire, under [[sync/conductors-and-cables]]
+- branch circuits of every kind, under [[sync/conductors-and-cables]]
+- the service arrangement, the utility coordination, the drop and the lateral, which party furnishes the lateral, the metering, the disconnecting means, the wiring method of the service, and the NFPA 70 Article 230 routing rules for the run, including its length inside the building, its seals, its protection from physical damage, and its clearances, under [[sync/electrical-service-entrance]]
+- cable rated above 1000 V, under [[sync/medium-voltage-cables]]
+- busway used as a service or as a feeder, whose bars are the conductors, under [[sync/busway]]
+- the raceway as a product, its supports, its fill, and its burial cover, under [[sync/raceways-and-conduit]]; the concrete-encased duct bank, under [[sync/underground-ductbank]]; and the manholes and handholes along it, under [[sync/utility-manholes-and-handholes]]
+- the grounding electrode conductor, the main bonding jumper, the supply-side bonding jumper, and the equipment grounding conductor of every feeder, including its size and its treatment in a parallel set, under [[sync/grounding-and-bonding]]
+- the lugs and terminals that the service equipment, the switchboard, the switchgear, and the panelboard furnish, under [[sync/low-voltage-switchboards]], [[sync/low-voltage-switchgear]], and [[sync/panelboards]]
+- the testing organization, its technicians, its instruments, its safety practice, and the compiled test report, under [[sync/electrical-acceptance-testing]]
+- the available fault current, the withstand of the conductors under it, and the settings of the feeder overcurrent devices, under [[sync/short-circuit-study]] and [[sync/protective-coordination-study]]
+- the crane and hoist runway, its runway conductors, and everything load side of the runway disconnecting means, under [[sync/overhead-material-handling]]
+- the telecommunications entrance facility and the pathways inside it, under [[sync/telecommunications-rooms-and-pathways]]
+- the label stock, lettering, and attachment of field markings, under [[sync/electrical-identification]]
−## Raceway and conduit systems that house these conductors are governed by [[sync/raceways-and-conduit]]; grounding electrode conductors, equipment grounding conductors, and bonding jumpers are governed by [[sync/grounding-and-bonding]]. {note}
+## The installation shall comply with [[parameter: adopted-electrical-code]] and with the amendments of the Authority Having Jurisdiction, and shall be made available for the inspections that authority requires.
−## Panelboard bus sizing, breaker coordination, and interior distribution beyond the panelboard lugs are governed by [[sync/panelboards]]. {note}
+## The service conductors and the feeders within this standard shall be as indicated on [[drawing: the one-line diagram]].
−## Medium-voltage feeders above 600 V and telecommunications or low-voltage signal cabling are outside this standard. {note}
+## Where a value stated on the one-line diagram or the feeder schedule for a particular service or feeder differs from the datasheet selection under this standard, the one-line diagram or the feeder schedule shall govern for that service or feeder.
# Referenced Standards {toc}
−## Materials, conductors, connectors, and installation shall comply with the latest adopted edition of each of the following standards unless a specific edition is cited.
+## Materials and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
−## Where the National Electrical Code adopted by the authority having jurisdiction differs from the editions referenced below, the adopted edition shall govern.
+## Where the contract documents, the serving utility's requirements, the Authority Having Jurisdiction, or two referenced standards impose conflicting requirements, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
−## Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
−
| Standard | Title |
|----------|-------|
−| NFPA 70 (NEC), Article 215 | National Electrical Code — Feeders |
−| NFPA 70 (NEC), Article 230 | National Electrical Code — Services |
−| NFPA 70 (NEC), Article 310 | National Electrical Code — Conductors for General Wiring |
−| NFPA 70 (NEC), Section 110.14 | National Electrical Code — Electrical Connections and Termination Temperature Ratings |
−| NFPA 70 (NEC), Section 250.122 | National Electrical Code — Size of Equipment Grounding Conductors |
−| UL 486A-486B | Wire Connectors for Use with Aluminum and/or Copper Conductors |
−| UL 486C | Splicing Wire Connectors |
−| UL 83 | Thermoplastic-Insulated Wires and Cables |
+| NFPA 70 | National Electrical Code (Articles 110, 215, 220, 225, 230, 240, 250, 300, 310, and 610) |
+| NFPA 70E | Standard for Electrical Safety in the Workplace |
| UL 44 | Thermoset-Insulated Wires and Cables |
−| ASTM B8 | Concentric-Lay-Stranded Copper Conductors, Hard, Medium-Hard, or Soft |
−| ASTM B230 | Aluminum 1350-H19 Wire for Electrical Purposes |
−| ASTM B800 | 8000 Series Aluminum Alloy Wire for Electrical Purposes, Annealed and Intermediate Tempers |
−| NEMA WC 70 / ICEA S-95-658 | Power Cables Rated 2000 V or Less for the Distribution of Electrical Energy |
+| UL 83 | Thermoplastic-Insulated Wires and Cables |
+| UL 854 | Service-Entrance Cables |
+| UL 1569 | Metal-Clad Cables |
+| UL 486A-486B | Wire Connectors |
+| UL 486C | Splicing Wire Connectors |
+| UL 486D | Sealed Wire Connector Systems |
+| ASTM B3 | Standard Specification for Soft or Annealed Copper Wire |
+| ASTM B8 | Standard Specification for Concentric-Lay-Stranded Copper Conductors, Hard, Medium-Hard, or Soft |
+| ASTM B496 | Standard Specification for Compact Round Concentric-Lay-Stranded Copper Conductors |
+| ASTM B800 | Standard Specification for 8000 Series Aluminum Alloy Wire for Electrical Purposes, Annealed and Intermediate Tempers |
+| ASTM B801 | Standard Specification for Concentric-Lay-Stranded Conductors of 8000 Series Aluminum Alloy for Subsequent Covering or Insulation |
+| ANSI/NEMA WC 70 / ICEA S-95-658 | Non-Shielded Power Cables Rated 2000 Volts or Less for the Distribution of Electrical Energy |
+| ANSI/NETA ATS | Standard for Acceptance Testing Specifications for Electrical Power Equipment and Systems |
+| IEEE 141 | Recommended Practice for Electric Power Distribution for Industrial Plants (Red Book) |
+| IEEE 241 | Recommended Practice for Electric Power Systems in Commercial Buildings (Gray Book) |
# Submittals {toc}
## Action Submittals {toc}
−### The Contractor shall submit the following action submittals for review before ordering conductors or connectors:
+### The Contractor shall submit the following for review before any service conductor is ordered and before any parallel set, tap, or transformer secondary conductor is installed:
−- Product data for each conductor type, including manufacturer, insulation type, voltage rating, temperature rating, and applicable UL listing.
−- Product data for each connector, lug, and splice device, including UL 486A-486B or UL 486C listing, AL/CU or copper-only marking, conductor size range, and published torque values.
−- A feeder and service conductor schedule showing, for each run, the circuit designation, conductor material, size, insulation type, number of conductors per phase, raceway, and overcurrent device rating.
−- Ampacity calculations for each feeder and service conductor, showing the termination temperature column used, ambient and bundling correction factors applied, and the continuous-load multiplier.
+- product data for each service conductor or cable type, identifying the listing, the conductor material and alloy, the insulation type and temperature rating, the voltage rating, and the applicable UL and ASTM standards
+- the service conductor sizing calculation, giving the calculated load under NFPA 70 Article 220, the continuous portion, the termination temperature column used, the ambient and adjustment corrections applied, and the resulting size and number of sets
+- the parallel set installation plan for each service and feeder run in parallel, showing the number of raceways, the conductors in each, the route of each raceway, and the planned length of each conductor
+- a schedule of every feeder tap and transformer secondary conductor, giving the tap rule applied, the conductor size, the length, the enclosure it runs in, and the overcurrent device that terminates it
+- product data for each line-side splice and tap connector, identifying the listing and the marking for use on the line side of service equipment
```datasheet
label: Action Submittals
type: checkbox
options:
− - Conductor product data (type, voltage, temperature rating, listing)
− - Connector and lug product data (listing, AL/CU marking, torque values)
− - Feeder and service conductor schedule
− - Ampacity calculations with temperature column and correction factors
+ - "Service conductor product data"
+ - "Service conductor sizing calculation"
+ - "Parallel set installation plan"
+ - "Feeder tap and transformer secondary conductor schedule"
+ - "Line-side splice and tap connector product data"
default:
− - Conductor product data (type, voltage, temperature rating, listing)
− - Connector and lug product data (listing, AL/CU marking, torque values)
− - Feeder and service conductor schedule
− - Ampacity calculations with temperature column and correction factors
+ - "Service conductor product data"
+ - "Service conductor sizing calculation"
+ - "Parallel set installation plan"
+ - "Feeder tap and transformer secondary conductor schedule"
+ - "Line-side splice and tap connector product data"
+constraint: all_of
```
−## Informational Submittals {toc}
+### No service conductor shall be ordered, and no parallel set shall be pulled, until the action submittal covering it has been reviewed and returned.
−### The Contractor shall submit the following informational submittals:
+### The product data and the voltage drop calculations for the feeder conductors as a product are submitted under [[sync/conductors-and-cables]] and are not repeated here. {note}
−- Manufacturer installation instructions for compression connectors, including die index, crimp count, and tooling.
−- Torque-tool calibration records for the torque-indicating tools used on field terminations.
−- Cable pulling tension and sidewall pressure calculations for runs that approach the manufacturer's published limits.
−
−```datasheet
−label: Informational Submittals
−type: checkbox
−options:
− - Compression connector installation instructions (die, crimp count, tooling)
− - Torque-tool calibration records
− - Pulling tension and sidewall pressure calculations
−default:
− - Compression connector installation instructions (die, crimp count, tooling)
− - Torque-tool calibration records
−```
−
## Closeout Submittals {toc}
−### The Contractor shall submit the following closeout submittals before final acceptance:
+### The Contractor shall submit the following before the service is presented to the utility for connection and before the feeders are accepted:
−- Insulation resistance test reports for each service and feeder conductor, including test voltage, duration, and measured values.
−- Completed torque verification records for all service and feeder terminations.
−- Marked-up record documents showing as-installed conductor sizes, materials, and routing where these differ from the contract documents.
+- the acceptance test report for the service conductors, giving the test voltage, the duration, each measured value, the acceptance criterion applied, and the tester's determination
+- the measured length of each conductor of every parallel set, recorded by set and by raceway
+- the parallel set current balance record and the feeder neutral current record, where those tests are selected, giving the load condition and each measured value
+- the as-installed record of every service conductor, parallel set, tap, and transformer secondary conductor whose size, count, route, or connector differs from the reviewed submittal
```datasheet
label: Closeout Submittals
type: checkbox
options:
− - Insulation resistance test reports
− - Torque verification records
− - As-installed record documents
+ - "Service conductor acceptance test report"
+ - "Parallel set conductor length record"
+ - "Current balance and neutral current records"
+ - "As-installed service and feeder conductor record"
default:
− - Insulation resistance test reports
− - Torque verification records
− - As-installed record documents
+ - "Service conductor acceptance test report"
+ - "Parallel set conductor length record"
+ - "Current balance and neutral current records"
+ - "As-installed service and feeder conductor record"
+constraint: all_of
```
# Quality Assurance {toc}
−## All service and feeder conductors shall be installed under the supervision of a qualified electrician licensed in the jurisdiction of the project.
+## Installer Qualifications {toc}
−## Conductor terminations on service equipment, switchgear, and panelboards shall be made only by personnel trained in the use of torque-indicating tools and compression tooling for the connectors specified.
+### Service conductors and feeders shall be installed by an electrical contractor licensed in the jurisdiction of the project, and the terminations and splices on the line side of the service equipment shall be made by electricians trained by the connector manufacturer or by the Contractor's own program in the connectors used.
−## Each conductor type, connector, and splice device shall bear the listing mark of a Nationally Recognized Testing Laboratory for the application and conductor material in which it is used.
+### Where the parties disagree whether an electrician's training covers the connector used, the Engineer of Record shall make the initial determination.
−## Substitution of conductor material, insulation type, or connector type from that shown in the approved submittals shall not be made without written approval of the Engineer of Record.
+## Listing and Marking {toc}
−## The single most common error in feeder design is sizing a conductor from the 90°C ampacity column and then terminating it in 75°C-rated equipment; this is a Code violation under NEC 110.14(C) and shall be guarded against in both design review and field installation. {note}
+### Every service conductor and cable shall be listed and labeled by a Nationally Recognized Testing Laboratory under UL 44, UL 83, UL 854, or UL 1569 for its type, and shall carry the surface marking that standard requires.
−# Conductor Material {toc}
+### Every connector used on the line side of the service equipment shall be listed under UL 486A-486B, UL 486C, or UL 486D for the conductor material and size range, and shall be marked as suitable for use on the line side of service equipment.
−## Both copper and AA-8000 series aluminum are accepted feeder conductor materials; the choice is an engineering trade-off between first cost, weight, ampacity per unit size, and termination discipline. {note}
+### A connector on the line side of the service equipment sits where no premises overcurrent device protects it; the line-side marking means the connector has been tested to carry and withstand fault current with only the utility's protection ahead of it. {note}
−## Copper offers higher ampacity per unit cross-section, more forgiving terminations, and is the default for smaller feeders and for tight raceway fill, at a substantially higher material cost. {note}
+## Substitutions {toc}
−## Aluminum is standard industry practice for large feeders and services; for sizes of 350 kcmil and above it delivers significant cost and weight savings with no performance penalty when AA-8000 alloy and listed AL/CU connectors are used and terminations are properly torqued. {note}
+### A change of service conductor material, type, size, or number of sets from the reviewed submittal shall be made only with the written approval of the Engineer of Record, and shall be accompanied by a revised sizing calculation and, where the material changes, by confirmation that every termination on the run is listed for the new material.
−## Specifying copper for large feeders without evaluating aluminum is a common and costly oversight; the design shall document the basis for a copper selection at 350 kcmil and above.
+# Environmental and Service Conditions {toc}
−## Conductors shall be copper or AA-8000 series aluminum alloy as scheduled for each feeder and service run.
+## Ambient Temperature Basis {toc}
−## Aluminum building-wire conductors shall be AA-8000 series aluminum alloy conforming to ASTM B800.
+### Service conductors shall be sized with the ambient temperature correction and the conductor count adjustment that [[sync/conductors-and-cables]] applies to feeders, taken at the hottest location along the run.
−## Aluminum 1350 alloy conductors conforming to ASTM B230 shall not be used as building wire and are permitted only where supplied as part of a listed utility service-entrance assembly.
+### Service conductors in a raceway exposed to direct sunlight outdoors shall be corrected for [[parameter: site-ambient-temperature-maximum]], with the rooftop temperature adder of NFPA 70 310.15(B)(2) added where the raceway is on or above a roof within the distance that section states.
−## Copper conductors shall conform to ASTM B8, Class B concentric stranding, unless flexible stranding is specified for bending-radius control.
+### A service raceway on a sunlit wall or a roof runs well above the 30 °C basis of the ampacity table for much of the day, and the service conductors in it carry the whole load of the building; a service sized at the table ampacity without the correction is the service that runs hot in the first summer. {note}
−## A reduced-cross-section neutral selected for an aluminum feeder shall use the same AA-8000 alloy and listed AL/CU terminations as the phase conductors.
+## Underground and Wet Locations {toc}
+### Service conductors and feeders in an underground raceway, a direct-buried cable, or a raceway in a wet location shall be of a type listed for wet locations, and a cable direct-buried shall be of a type listed for direct burial.
+
+### Where a service or a feeder runs in a concrete-encased duct bank with other loaded circuits, its ampacity shall be established for the duct bank configuration and the soil thermal resistivity in accordance with NFPA 70 310.15 and Informative Annex B, rather than taken from NFPA 70 Table 310.16 alone.
+
+### An underground raceway is a wet location over the life of the installation because groundwater enters through the joints, and a duct bank with several loaded circuits heats the earth around it so that no circuit in it runs at the free-raceway ampacity; the duct bank itself is built under [[sync/underground-ductbank]], and the ampacity of the conductors inside it is a consequence of how many circuits it carries. {note}
+
+# Service Conductors {toc}
+
+## Service Conductor Type {toc}
+
+### The service conductor or cable type shall be as indicated in the datasheet.
+
```datasheet
−label: Conductor material
−type: radio
+label: Service Conductor Type
+type: select
options:
− - Copper (ASTM B8)
− - Aluminum, AA-8000 series (ASTM B800)
−default: Copper (ASTM B8)
+ - "Type THHN/THWN-2 single conductors"
+ - "Type XHHW-2 single conductors"
+ - "Type RHW-2 single conductors"
+ - "Type USE-2 single conductors"
+ - "Type SE cable, Type SEU or SER"
+ - "Type USE cable assembly, direct buried"
+ - "Type MC cable listed for service-entrance use"
```
+### THHN/THWN-2 is the thermoplastic building wire most raceway services are pulled with, at the smallest diameter and the lowest cost; XHHW-2 is a thermoset insulation that does not soften under sustained heat and absorbs less moisture, which suits a service raceway that runs hot or wet and a large aluminum service where thermal margin at the lugs matters, at a slightly larger diameter; RHW-2 is a thermoset type with a separate jacket that serves the same locations where the Owner's standard calls for it; USE-2 is the wet-location and direct-burial type that carries an underground service from the utility's terminals and is also listed for the raceway run inside; Type SE cable is the cable assembly of most dwelling and small commercial services and costs least where the serving utility and the Authority Having Jurisdiction accept it; a direct-buried Type USE cable assembly removes the raceway and cannot be replaced without re-excavation; Type MC cable listed for service-entrance use serves an indoor run between a transformer vault and the service equipment where a raceway cannot be routed. The wiring method of the service, raceway, cable, or busway, is selected under [[sync/electrical-service-entrance]], and where that selection is busway the bars of the busway are the service conductors, under [[sync/busway]], and the conductor selections of this article do not apply. {note}
+
+### Service conductors shall be rated not less than 600 V.
+
+### The service conductor type shall be listed for every location the run passes through, including the underground portion, the portion exposed to the weather, and the portion inside the building.
+
+## Service Conductor Material {toc}
+
+### The service conductor material shall be as indicated in the datasheet.
+
```datasheet
−label: Copper conductor stranding class
+label: Service Conductor Material
type: radio
options:
− - Class B concentric (standard building wire)
− - Class C concentric (improved flexibility)
− - Flexible stranding (bending-radius control)
−default: Class B concentric (standard building wire)
+ - "Copper"
+ - "Aluminum"
+ - "Copper-clad aluminum"
+default: "Copper"
```
−# Insulation and Conductor Type {toc}
+### Copper carries more current per unit of cross-section, terminates on every listed lug without a compound, and is less subject to creep at the terminal, at the highest material cost; aluminum weighs about half as much and costs a fraction of copper for the same ampacity at the sizes a service uses, and it is what most utilities run on their own side of the service point, at the cost of a larger conductor and raceway, lugs listed for aluminum, and the oxide-inhibiting practice at every termination; copper-clad aluminum weighs and costs near aluminum and is terminated as aluminum, and serves where the Owner wants a copper surface at the strand without the weight of copper. A service point at the utility's aluminum lugs takes any of the three. {note}
−## Insulation type is selected from the wet-versus-dry location, the temperature rating needed to apply correction factors, and the conductor type listed for the application. {note}
+### Copper service conductors shall be soft-drawn or annealed copper conforming to ASTM B3 for solid wire or ASTM B8 for concentric-lay stranding, or ASTM B496 for compact stranding.
−## THHN/THWN-2 is the most commonly specified type for feeders in conduit; it is dual-rated 90°C in dry locations and 90°C wet as THWN-2, is economical, and has a small overall diameter that favors raceway fill. {note}
+### Aluminum and copper-clad aluminum service conductors shall be of AA-8000 series aluminum alloy conforming to ASTM B800 and ASTM B801, in accordance with NFPA 70 310.3(B).
−## XHHW-2 is a thermoset insulation rated 90°C in both wet and dry locations; it is preferred for large aluminum feeders, for wet and underground runs, and where superior heat and moisture resistance is wanted, at a slightly larger diameter than THHN/THWN-2. {note}
+### Aluminum 1350 conductor remains in use on the utility's side of the service point and in utility-furnished lateral conductors, and NFPA 70 310.3(B) does not accept it for conductors the Contractor furnishes, because its creep and its thermal expansion loosen a bolted terminal over the years in a way the 8000 series alloy was developed to resist. {note}
−## USE-2 and RHW-2 are used for direct-buried and underground-in-conduit service feeders where a wet-rated, sunlight-resistant, or burial-rated conductor is required. {note}
+### Where aluminum or copper-clad aluminum service conductors are selected, every lug, connector, and terminal on the run shall be listed and marked for aluminum, and the terminations shall be prepared and made as the Aluminum Terminations article of [[sync/conductors-and-cables]] requires.
−## The 90°C rating of any of these insulations is used only to obtain headroom for ambient and bundling correction; the final ampacity is still limited by the termination temperature under NEC 110.14(C). {note}
+### Service conductors 8 AWG and larger shall be stranded.
−## Feeder and service conductors in conduit shall be type THHN/THWN-2, XHHW-2, or USE-2/RHW-2 as scheduled for the location.
+## Service Conductor Sizing {toc}
−## Conductors in wet locations, underground raceways, and direct-burial applications shall be rated for wet locations at 90°C.
+### Each set of service conductors shall have an ampacity, after the correction and adjustment factors of NFPA 70 310.15, not less than the noncontinuous load plus 125 % of the continuous load calculated under NFPA 70 Article 220, in accordance with NFPA 70 230.42(A).
−## Thermoplastic-insulated conductors shall be listed to UL 83; thermoset-insulated conductors shall be listed to UL 44.
+### Where the service overcurrent device and the assembly it is installed in are listed for operation at 100 % of their rating, the service conductors may be sized at 100 % of the continuous load plus the noncontinuous load, as NFPA 70 230.42(A) Exception No. 1 permits.
−## Insulation types shall not be mixed within a single raceway unless the raceway fill and the temperature ratings of all conductors present have been verified compatible.
+### The ampacity of the service conductors shall be not less than the rating of the service disconnecting means, in accordance with NFPA 70 230.42(B), except that where the conductor ampacity does not correspond to a standard overcurrent device rating, the next higher standard rating may protect them where that rating does not exceed 800 A, as NFPA 70 230.90(A) Exception No. 2 permits.
−## All conductors of a feeder, including the neutral and any parallel sets, shall use the same insulation type.
+### Where grouped service disconnects are furnished, the service conductors shall have an ampacity not less than the calculated load of the whole service, and the sum of the ratings of the grouped disconnects may exceed the ampacity of the service conductors only as NFPA 70 230.90(A) Exception No. 3 permits.
−```datasheet
−label: Conductor insulation type
−type: radio
−options:
− - THHN/THWN-2 (90°C dry / 90°C wet, thermoplastic)
− - XHHW-2 (90°C wet and dry, thermoset)
− - USE-2/RHW-2 (underground / wet, burial-rated)
−default: THHN/THWN-2 (90°C dry / 90°C wet, thermoplastic)
−```
+### The size, the number of conductors per phase, and the number of sets of the service conductors shall be as indicated on [[drawing: the one-line diagram]].
−```datasheet
−label: Conductor voltage rating
−type: radio
−options:
− - 600 V
− - 1000 V
−default: 600 V
−```
+### The grounded service conductor shall be sized for the maximum unbalanced load under NFPA 70 220.61, and shall be not smaller than NFPA 70 250.24(C) and Table 250.102(C)(1) require for the largest ungrounded service conductor or for the equivalent area of a parallel set.
−# Ampacity Sizing {toc}
+### Where the service conductors are installed in parallel in more than one raceway, the grounded service conductor shall be run in each raceway, sized under NFPA 70 250.24(C)(2) on the ungrounded conductors in that raceway and not smaller than 1/0 AWG.
−## Conductor ampacity is established in two layers: a base table ampacity from NEC Table 310.16, then correction and adjustment factors for ambient temperature and bundling, all reconciled against the termination temperature limit. {note}
+### The grounded service conductor carries the unbalanced load in service and the whole fault current when a service conductor faults to the enclosure, and the second duty is why NFPA 70 sizes it from the ungrounded conductors as well as from the load; the grounding electrode conductor and the main bonding jumper it lands beside are sized under [[sync/grounding-and-bonding]]. {note}
−## Service conductors are sized to NEC 230.42 and feeder conductors to NEC 215.2; both require the conductor ampacity to equal or exceed the noncontinuous load plus 125% of the continuous load. {note}
+## Service Conductor Termination Temperature {toc}
−## Conductors shall be sized so that the allowable ampacity equals or exceeds the noncontinuous load plus 1.25 times the continuous load.
+### Service conductors shall be sized from the ampacity column of NFPA 70 Table 310.16 corresponding to the termination temperature rating indicated in the datasheet, and the 90 °C column shall be used only as the starting value for correction and adjustment, with the corrected ampacity limited to the value of the termination temperature column, in accordance with NFPA 70 110.14(C).
−## Conductor ampacity shall be determined from NEC Table 310.16 for the conductor material, size, and applicable temperature column.
+```datasheet
+label: Service Conductor Termination Temperature Rating
+type: range
+unit: °C
+options:
+ min: 60
+ max: 90
+ setpoints: [60, 75, 90]
+default: 75
+constraint: exact
+```
−## The base table ampacity shall be reduced by the ambient temperature correction factor of NEC Table 310.15(B)(1) wherever the ambient exceeds 30°C (86°F).
+### The temperature rating of the lowest-rated termination on the run, the meter socket, the current transformer cabinet, the line-side splice, or the service disconnect, is the rating that governs, and 75 °C is the marking on nearly every meter socket and service disconnect above 100 A; a 60 °C basis applies to a small service whose socket or disconnect is marked for 60 °C, and a 90 °C basis is claimed only where every termination on the run is marked for 90 °C, which few service equipment listings are. {note}
−## The base table ampacity shall be reduced by the adjustment factor of NEC Table 310.15(C)(1) wherever more than three current-carrying conductors share a raceway.
+### The Contractor shall verify the termination temperature marking of the meter socket, the current transformer cabinet, and the service disconnect before the service conductors are ordered, and shall report a marking lower than the datasheet value to the Engineer of Record in writing before ordering.
−## Where a calculated conductor ampacity does not correspond to a standard overcurrent device rating, the next-higher standard device rating may be used in accordance with NEC 240.4(B) for devices rated 800 A and below.
+## Line-Side Splices and Terminations {toc}
−## The default for a 200 A service or feeder is 4/0 AWG copper THHN/THWN-2 (230 A at the 75°C column) or 350 kcmil aluminum XHHW-2 (260 A at the 75°C column). {note}
+### Service conductor terminations and splices shall be made as the Connectors and Terminations section of [[sync/conductors-and-cables]] requires, with the additional requirements of this article.
−## The feeder or service overcurrent device rating shall be specified, sized to the noncontinuous load plus 1.25 times the continuous load it serves.
+### Where [[sync/electrical-service-entrance]] permits a splice or a tap in the service conductors, the connector shall be of the type indicated in the datasheet.
```datasheet
−label: Feeder or service rating (overcurrent device)
+label: Service Conductor Splice and Tap Connector
type: select
options:
− - 100 A
− - 125 A
− - 150 A
− - 200 A
− - 225 A
− - 400 A
− - 600 A
− - 800 A
− - 1200 A
− - 1600 A
− - 2000 A
−default: 200 A
+ - "Compression splice with a listed insulating cover"
+ - "Insulated mechanical multi-tap connector"
+ - "Listed sealed underground splice kit"
```
−```datasheet
−label: Continuous load fraction (for 125% sizing)
−type: range
−unit: "%"
−min: 0
−max: 100
−step: 5
−default: 100
−```
+### A compression splice crimped with the listed die and covered with a heat-shrink or molded cover makes a permanent joint with the lowest resistance and is what a splice inside a wireway or a pull box takes; an insulated mechanical multi-tap connector takes several conductors of a range of sizes under set screws in an insulated block and is what a tap to grouped disconnects or a transition between conductor sizes takes, at the cost of a torque check; a sealed underground splice kit listed under UL 486D is the only connector that serves a splice in a handhole or a direct-buried run, where the joint sits in water. {note}
−# Termination Temperature Coordination {toc}
+### Each line-side connector shall be installed with the die, the crimp count, and the tooling the connector's listing requires for a compression connector, or torqued to the published value with a calibrated tool for a mechanical connector, and each shall be insulated to the full voltage rating of the conductor before the enclosure is closed.
−## The temperature column used for ampacity is governed by the lowest-rated termination in the circuit, not by the conductor insulation; this is NEC 110.14(C) and is the most frequently misapplied rule in feeder design. {note}
+### The service conductors shall land in the service equipment on the lugs that equipment furnishes under its product standard, and where the conductor size or count exceeds the range of those lugs the Contractor shall report the mismatch to the Engineer of Record in writing before the equipment is released for manufacture, rather than reduce the conductor to fit.
−## Equipment rated 100 A and below, and conductors sized 14 AWG through 1 AWG, default to the 60°C column unless the equipment and conductors are listed for a higher temperature. {note}
+### A conductor forced into a lug below its size range, or two conductors landed in a lug listed for one, is a termination that is not listed, and it is the one the infrared survey finds in the first summer; the lug range is fixed when the equipment is ordered, so the conductor size and the lug range are reconciled on the submittals, not in the field. {note}
−## Equipment rated above 100 A, and conductors larger than 1 AWG, default to the 75°C column unless the equipment is marked for terminations at a higher temperature. {note}
+# Feeder Sizing and Protection {toc}
−## A 90°C conductor insulation may be used to apply ambient and bundling correction from the 90°C ampacity, but the corrected result shall not exceed the ampacity of the termination temperature column unless the equipment is listed for 90°C terminations. {note}
+## Feeder Calculated Load {toc}
−## The temperature column used for conductor ampacity shall be the lowest temperature rating among the conductor, the connected equipment terminals, and the connectors in the circuit.
+### Each feeder shall be sized to the calculated load determined under NFPA 70 Article 220, applying the demand factors that article permits for the loads the feeder serves.
−## Feeder and service conductors terminating on equipment rated above 100 A shall be sized using the 75°C column of NEC Table 310.16 unless the equipment is listed and marked for terminations at 90°C.
+### The calculated load, the overcurrent device rating, the conductor size, and the number of conductors per phase of each feeder shall be as indicated on [[drawing: the feeder schedule]].
−## Where correction or adjustment factors are applied from the 90°C ampacity, the resulting ampacity shall be limited to the value permitted by the applicable termination temperature column.
+### Each feeder shall have an ampacity, after the correction and adjustment factors applied under [[sync/conductors-and-cables]], not less than the noncontinuous load plus 125 % of the continuous load, in accordance with NFPA 70 215.2(A)(1), except that where the feeder overcurrent device and its assembly are listed for operation at 100 % of their rating the feeder may be sized at 100 % of the continuous load plus the noncontinuous load.
−## The temperature column selected for each feeder shall be recorded in the ampacity calculation submittal.
+### The 125 % factor on the continuous load exists to keep an ordinary molded-case device, which is tested to carry its rating in open air, from tripping on heat inside an enclosure under a three-hour load; a device listed for 100 % operation has been tested in the assembly it is installed in, and the factor is already in the listing. {note}
−```datasheet
−label: Termination temperature rating (lowest in circuit)
−type: radio
−options:
− - 60°C
− - 75°C
− - 90°C
−default: 75°C
−```
+### A feeder supplying a crane or hoist runway disconnecting means shall have an ampacity not less than NFPA 70 610.14(E) establishes for the motors it supplies, with the demand factors that section permits, and its overcurrent protection shall be as NFPA 70 610.41 requires; the runway conductors and everything on the load side of the runway disconnect are under [[sync/overhead-material-handling]].
−# Environmental and Service Conditions {toc}
+### A feeder to a separate building or structure shall comply with NFPA 70 Article 225 for its disconnecting means at the structure and for the single feeder NFPA 70 225.30 permits, and the grounding electrode and the equipment grounding conductor at the structure shall be as [[sync/grounding-and-bonding]] requires.
−## Ambient temperature and conductor bundling are the two field conditions that most often force a conductor upsize, and both are routinely overlooked when feeders pass through hot or congested spaces. {note}
+## Feeder Overcurrent Protection {toc}
−## Mechanical rooms, attics, rooftop runs, and exterior exposed raceways frequently exceed the 30°C (86°F) table basis and require ambient correction; for example, at 40°C (104°F) a 90°C conductor is multiplied by 0.91, and at 50°C (122°F) by 0.82. {note}
+### Each feeder shall be protected at its ampacity, after correction and adjustment, by the overcurrent device at its supply end, in accordance with NFPA 70 240.4.
−## Failing to apply ambient correction in a high-ambient space is a common design error that surfaces as a thermal failure or an inspection rejection rather than a design RFI. {note}
+### Where the feeder ampacity does not correspond to a standard overcurrent device rating, the next higher standard rating may protect the feeder only where that rating does not exceed 800 A, in accordance with NFPA 70 240.4(B).
−## The design ambient temperature for each feeder run shall be established from the actual installed environment and shall not be assumed to be 30°C (86°F) without verification.
+### Where the overcurrent device is rated above 800 A, the feeder ampacity shall be not less than the rating of the device, in accordance with NFPA 70 240.4(C).
−## Ambient temperature correction shall be applied to every feeder routed through a space whose maximum ambient exceeds 30°C (86°F).
+### The rating and the settings of each feeder overcurrent device are established under [[sync/protective-coordination-study]], and this standard sizes the feeder to carry what that device lets through; a feeder whose ampacity falls short of a device setting changed during the study is the coordination that was never checked against the conductor. {note}
−## Underground and wet-location conductors shall be wet-rated for the installed condition, including the effect of duct-bank thermal resistivity where applicable.
+## Largest Single Conductor {toc}
−```datasheet
−label: Design ambient temperature
−type: range
−unit: "°C"
−min: 30
−max: 55
−step: 5
−default: 30
−```
+### The largest single conductor size used for a service or a feeder before the conductors are installed in parallel shall be as indicated in the datasheet.
```datasheet
−label: Installed location condition
−type: radio
+label: Largest Single Conductor Size
+type: select
options:
− - Dry, indoor conditioned
− - Dry, high-ambient (mechanical room, attic, rooftop)
− - Wet or damp location
− - Underground in raceway
− - Direct burial
−default: Dry, indoor conditioned
+ - "350 kcmil"
+ - "500 kcmil"
+ - "600 kcmil"
+ - "750 kcmil"
+ - "1000 kcmil"
+default: "500 kcmil"
```
−# Overcurrent Coordination {toc}
+### A conductor above 500 kcmil gains little ampacity for its added copper, because the current crowds toward the surface of a large conductor, and it is stiff enough that a 750 kcmil or 1000 kcmil conductor needs a larger pull box, a larger bending radius, and a lug that most distribution equipment does not furnish as standard; 500 kcmil is the size most equipment lugs accept and most contractors keep on hand, 350 kcmil suits a project that wants lighter pulls at the cost of more parallel sets, and 600 kcmil and above suit a project with few raceways available and equipment ordered with lugs to match. {note}
−## Conductor ampacity and overcurrent device rating are coordinated so that the conductor is protected at its corrected ampacity, with the limited next-standard-size allowance recognized for devices 800 A and below. {note}
+### Where the one-line diagram or the feeder schedule shows a single conductor larger than the datasheet value, the schedule shall govern for that run.
−## The corrected ampacity of the conductor shall equal or exceed the rating of the overcurrent device protecting it, except as permitted by the next-standard-size rule of NEC 240.4(B).
+## Parallel Conductor Sets {toc}
−## The next-standard-size rule shall not be applied to overcurrent devices rated above 800 A.
+### Service conductors and feeders installed in parallel shall comply with NFPA 70 310.10(G) and with the Parallel Conductors article of [[sync/conductors-and-cables]], and the number of sets of each run shall be as indicated on [[drawing: the feeder schedule]].
−## Tap conductors shall be sized and protected in accordance with the applicable feeder tap rules of NEC 240.21(B) and shall be no smaller than the tap rule permits.
+### Where a parallel set is installed in more than one raceway or cable, each raceway or cable shall carry the arrangement of conductors indicated in the datasheet.
−## Where a feeder supplies multiple subpanels, the overcurrent coordination for each downstream device shall be verified against the upstream device per the coordination study, if one is required for the project.
+```datasheet
+label: Parallel Set Raceway Arrangement
+type: radio
+options:
+ - "One conductor of each phase and the neutral in each raceway"
+ - "Isolated-phase arrangement in nonmetallic underground raceways"
+default: "One conductor of each phase and the neutral in each raceway"
+```
−# Neutral and Grounded Conductor {toc}
+### Running one conductor of each phase and the neutral in each raceway keeps the magnetic fields of the set balanced inside every raceway, which NFPA 70 300.3(B)(1) and 300.20 require in a ferrous raceway and which keeps every raceway of the set at the same impedance so the conductors share current; an isolated-phase arrangement, with all the conductors of one phase in one raceway, is permitted only in nonmetallic raceways run underground as NFPA 70 300.3(B)(1) Exception No. 2 and 300.5(I) Exception No. 2 provide, and it suits a long underground duct bank where it simplifies the pull, at the cost of unequal reactance between phases and of a raceway that is never converted to metal. {note}
−## The grounded (neutral) feeder conductor is sized for the maximum unbalanced load, but never smaller than the minimum equipment-grounding-conductor size of NEC Table 250.122 for the overcurrent device rating. {note}
+### Where an isolated-phase arrangement is selected, the raceways shall be nonmetallic, shall be run underground, and shall be installed in close proximity to one another as NFPA 70 300.5(I) Exception No. 2 requires, and the metal enclosure each raceway enters shall be arranged as NFPA 70 300.20(B) requires.
−## A reduced neutral is permissible for predominantly linear loads, but nonlinear loads such as variable-frequency drives and electronic equipment drive third-harmonic current that adds on the neutral and warrants a full-size or oversized neutral. {note}
+### The conductors of each phase and of the neutral in a parallel set shall be cut to the same length, and the Contractor shall measure and record the installed length of each conductor of each set.
−## Sizing a reduced neutral on a feeder that serves significant nonlinear load is a recurring error that produces neutral overheating; the harmonic content shall be evaluated before reducing the neutral.
+### Where the conductors of a parallel set terminate at equipment, each conductor of the set shall land on its own lug or on a lug listed for the number of conductors it holds, and the conductors of one phase shall not be stacked on a lug listed for one.
−## The grounded (neutral) conductor shall be sized for the maximum unbalanced load calculated under NEC 220.61.
+### A parallel set shares current by impedance, and the impedance of each conductor is its length; a set whose conductors differ by a few feet in a short run divides its current unevenly, and the shorter conductor carries more than its share and runs hotter, which is why the length is measured and recorded rather than assumed from the raceway length. {note}
−## The grounded (neutral) conductor shall not be smaller than the equipment grounding conductor size required by NEC Table 250.122 for the feeder overcurrent device.
+## Feeder Neutral Sizing {toc}
−## A full-size or oversized neutral shall be provided where the feeder serves significant nonlinear load that produces third-harmonic neutral current.
+### The grounded conductor of each feeder shall be sized on the basis indicated in the datasheet, and shall be not smaller than the equipment grounding conductor NFPA 70 250.122 requires for the feeder overcurrent device, in accordance with NFPA 70 215.2(A)(2).
```datasheet
−label: Neutral conductor sizing
+label: Feeder Neutral Sizing Basis
type: radio
options:
− - Full-size neutral (equal to phase)
− - Reduced neutral (per NEC 220.61, linear load)
− - Oversized neutral (harmonic / nonlinear load)
−default: Full-size neutral (equal to phase)
+ - "Full size, equal to the phase conductors"
+ - "Reduced to the maximum unbalanced load under NFPA 70 220.61"
+ - "Oversized to 200 % of the phase conductor ampacity"
+default: "Full size, equal to the phase conductors"
```
−# Parallel Conductor Assemblies {toc}
+### A full-size neutral costs one more conductor at the phase size and never has to be revisited when the load changes, which is why most projects carry it on every feeder; a neutral reduced to the unbalanced load under NFPA 70 220.61 saves copper on a feeder whose load is balanced three-phase equipment, and the reduction is lost the day a nonlinear load is added, since 220.61(C) forbids it where the load is largely nonlinear; a 200 % neutral serves a feeder to a panelboard whose load is electronic, where the third-harmonic currents of the three phases add in the neutral rather than cancel, and it is paired with the 200 % neutral bus selected under [[sync/panelboards]]. {note}
−## Paralleling distributes a single phase across two or more conductors per phase, and becomes the practical configuration for feeders of roughly 400 A and above where a single conductor would be unwieldy or unavailable. {note}
+### Where the feeder serves a load that is more than half nonlinear, the neutral shall not be reduced below the phase conductor size, and the neutral shall be counted as a current-carrying conductor for the adjustment factors applied under [[sync/conductors-and-cables]].
−## Parallel conductors are permitted only in sizes of 1/0 AWG and larger; conductors smaller than 1/0 AWG shall not be paralleled regardless of the load calculation.
+### Where a 200 % neutral is selected, the neutral shall be two conductors of the phase size in parallel or one conductor of twice the phase ampacity, and the neutral lug of the equipment at each end shall be listed for the conductor furnished.
−## For the parallel set to share current equally, all conductors of a given phase must be identical, and the same is required of the neutral set; any difference in length, material, or termination forces an unequal current split and localized overheating.
+## Feeder Voltage Drop {toc}
−## Specifying parallel conductors smaller than 1/0 AWG, or allowing unequal conductor lengths between parallel raceways, are recurring field problems that the specification shall foreclose explicitly.
+### Each feeder shall be sized so that the voltage drop from its supply end to its load end, at the calculated load and at the operating temperature of the conductor, does not exceed the value indicated in the datasheet.
−## Conductors shall be paralleled only in sizes of 1/0 AWG and larger.
+```datasheet
+label: Feeder Voltage Drop
+type: range
+unit: '%'
+options:
+ min: 1
+ max: 5
+ setpoints: [1, 1.5, 2, 2.5, 3, 4, 5]
+constraint: max
+```
−## All conductors of each phase in a parallel set shall be the same length, the same conductor material, the same insulation type, the same cross-sectional area, and shall be terminated in the same manner.
+### Where [[parameter: adopted-energy-code]] limits the voltage drop of a feeder to a lower value than the datasheet, the lower value shall govern.
−## The neutral conductors of a parallel feeder shall themselves be paralleled and shall meet the same equal-length, material, insulation, and termination requirements as the phase conductors.
+### NFPA 70 215.2(A) carries an informational note that a feeder voltage drop of 3 % and a combined feeder and branch circuit drop of 5 % provide reasonable efficiency of operation, and several editions of the energy code enforced 2 % on feeders and 3 % on branch circuits as a requirement; a tighter feeder criterion buys motor starting torque and steady voltage at electronic loads at the cost of a larger conductor on every long feeder, and a looser one is accepted on a short feeder to a lighting load whose voltage the drivers tolerate. {note}
−## Where parallel conductors are installed in separate raceways, each raceway shall contain one conductor of each phase and the associated neutral so that the magnetic fields balance.
+### The combined feeder and branch circuit voltage drop criterion is selected under [[sync/conductors-and-cables]], and the feeder criterion here is the portion of that total the feeder is allowed to consume. {note}
+## Feeder Taps and Transformer Secondary Conductors {toc}
+
+### Whether feeder conductors may be tapped under the tap rules of NFPA 70 240.21(B) shall be as indicated in the datasheet.
+
```datasheet
−label: Conductors per phase
−type: select
+label: Feeder Tap Rule Use
+type: radio
options:
− - 1 (single conductor per phase)
− - 2 parallel
− - 3 parallel
− - 4 parallel
−default: 1 (single conductor per phase)
+ - "Taps permitted under NFPA 70 240.21(B)"
+ - "Taps not permitted"
+default: "Taps permitted under NFPA 70 240.21(B)"
```
−# Connectors, Lugs, and Splices {toc}
+### Where taps are permitted, a tap shall be made only where the one-line diagram shows it, and where taps are not permitted every feeder shall be protected at its ampacity at its supply end.
−## Connector selection follows the conductor material and the termination method; the two dominant families are mechanical set-screw connectors and compression (crimp) connectors, each listed for specific conductor materials and ranges. {note}
+### A tap lets one feeder device serve several pieces of equipment through short unprotected conductors, which removes a device and an enclosure from every tap and is how a transformer, a gutter feeding grouped disconnects, and a motor control center lineup are commonly supplied; forbidding taps puts a device at the head of every conductor, which costs devices and space and is what an Owner chooses when its maintenance staff want every conductor protected at its source and no length of feeder that relies on a device ten times its ampacity. {note}
−## Mechanical set-screw connectors and connector blocks are field-adjustable and common for service-entrance taps; compression lugs give a permanent, low-resistance termination preferred for switchgear and panelboard bus connections. {note}
+### Where a tap is made, the tap conductors shall comply with one of the rules of NFPA 70 240.21(B) for their length, their ampacity relative to the feeder device, and their termination in a single overcurrent device, and the rule applied shall be stated on the tap schedule submitted.
−## A direct aluminum-to-copper connection requires a connector listed and marked AL/CU; using a copper-only lug on an aluminum conductor causes a high-resistance joint that overheats and fails, and is a leading cause of service fires. {note}
+### Tap conductors shall be enclosed in a raceway or an enclosure for their whole length, shall not supply another tap, and shall terminate in a single overcurrent device that limits the load to the tap conductor ampacity.
−## Compression terminations must be made with the matching die and crimp count from the connector's listing; a connector crimped with the wrong die is not a listed termination.
+### Conductors from the secondary of a transformer to the first overcurrent device shall comply with NFPA 70 240.21(C) for their length and their ampacity relative to the primary device, and the secondary conductors of a transformer with a single-phase two-wire or a three-phase delta-delta secondary may be protected by the primary device only as NFPA 70 240.21(C)(1) permits.
−## Connectors and lugs shall be listed to UL 486A-486B and shall be marked for the conductor material on which they are used.
+### Where the tap or the transformer secondary conductors are indicated on the one-line diagram, their size, length, and the device they terminate in shall be as indicated on [[drawing: the one-line diagram]].
−## Splicing connectors shall be listed to UL 486C for the splice or tap application in which they are used.
+# Testing {toc}
−## Connectors used on aluminum conductors, and connectors joining aluminum to copper, shall be marked AL/CU.
+## Service Conductor Insulation Resistance {toc}
−## Copper-only connectors shall not be used on aluminum conductors.
+### Before the service conductors are connected at the service point and before they are landed in the service equipment, each service conductor shall be tested for insulation resistance with a direct-current test set, each conductor against ground with the other conductors of the set grounded, and each conductor against each other conductor, at the test voltage indicated in the datasheet applied for not less than one minute.
−## Compression connectors shall be installed with the die, crimp count, and tooling specified in the connector manufacturer's listing.
−
−## The conductor size selected for each termination shall fall within the listed conductor range of the lug; where it does not, an oversized-lug kit shall be specified rather than forcing the conductor into an undersized lug.
−
```datasheet
−label: Termination connector type
−type: radio
+label: Service Conductor Insulation Resistance Test Voltage
+type: range
+unit: V dc
options:
− - Compression (crimp) lug
− - Mechanical (set-screw) connector
−default: Compression (crimp) lug
+ min: 500
+ max: 2500
+ setpoints: [500, 1000, 2500]
+default: 1000
+constraint: exact
```
+### The insulation resistance of each service conductor, corrected to 20 °C, shall be not less than the value indicated in the datasheet.
+
```datasheet
−label: Connector material rating
−type: radio
+label: Service Conductor Insulation Resistance
+type: range
+unit: MΩ
options:
− - AL/CU rated (aluminum or copper)
− - Copper only
−default: AL/CU rated (aluminum or copper)
+ min: 50
+ max: 1000
+ setpoints: [50, 100, 250, 500, 1000]
+default: 100
+constraint: min
```
−# Termination Torque {toc}
+### ANSI/NETA ATS Table 100.1 assigns 1000 V dc and a 100 MΩ minimum to 600 V class conductors, and a 500 V dc test at the same minimum serves a conductor whose attached equipment the tester cannot isolate; the 2500 V dc setpoint serves a 1000 V rated conductor or an Owner that wants a stressed test of a long underground service, and the higher minimum values suit a new conductor in a dry raceway, where a reading near 100 MΩ on a short run is already a sign of moisture or damage. {note}
−## Every mechanical and compression-mechanical termination is tightened to the manufacturer's published torque using a torque-indicating tool; both under-torque and over-torque produce high-resistance, overheating joints and are a leading cause of service failures and fires. {note}
+### A service conductor that fails the insulation resistance test shall not be connected, the Contractor shall locate the cause and replace the conductor or the set, and the cost of the replacement and of every repeated test shall be borne by the Contractor.
−## NEC 110.14(D) requires terminations to be torqued to the value indicated on the equipment or in the manufacturer's instructions, applied with a calibrated torque tool; typical values range from about 250 in-lb for 4/0 AWG copper to about 600 in-lb for 600 kcmil. {note}
+### The test is performed before the conductors are connected because once they are landed on the utility's terminals and the service disconnect, the premises side can no longer be isolated without the utility, and a defect found then costs an outage; [[sync/electrical-service-entrance]] holds the service from the utility's connection until this test is recorded. {note}
−## Terminations shall be tightened to the torque value published by the connector or equipment manufacturer.
+## Feeder and Parallel Set Tests {toc}
−## Torque shall be applied with a calibrated torque-indicating tool in accordance with NEC 110.14(D).
+### The feeders and the parallel sets within this standard shall receive the tests indicated in the datasheet, in addition to the insulation resistance and continuity tests of the conductor product performed under [[sync/conductors-and-cables]].
−## Torque-tool calibration shall be current at the time of termination and the calibration record shall be available for review.
+```datasheet
+label: Service and Feeder Acceptance Tests
+type: checkbox
+options:
+ - "Phase identification and continuity of each service conductor set from the service point to the service disconnect"
+ - "Current balance across the conductors of each parallel set under load"
+ - "Neutral current of each feeder serving nonlinear load under load"
+ - "Phase rotation at the load end of each three-phase feeder"
+default:
+ - "Phase identification and continuity of each service conductor set from the service point to the service disconnect"
+ - "Current balance across the conductors of each parallel set under load"
+ - "Phase rotation at the load end of each three-phase feeder"
+constraint: all_of
+```
−## Each service and feeder termination shall be torque-verified and the result recorded for the closeout submittal.
+### Where the current balance test is selected, the current in each conductor of a parallel set shall be measured with the feeder carrying not less than 50 % of its calculated load, and the current in any conductor shall not differ from the average of the conductors of that phase by more than the value indicated in the datasheet.
```datasheet
−label: Torque verification method
−type: radio
+label: Parallel Set Current Balance Tolerance
+type: range
+unit: '%'
options:
− - Torque-indicating wrench (calibrated)
− - Torque screwdriver (calibrated)
−default: Torque-indicating wrench (calibrated)
+ min: 5
+ max: 20
+ setpoints: [5, 10, 15, 20]
+default: 10
+constraint: max
```
−# Routing and Bending Radius {toc}
+### A parallel set whose conductors are cut to the same length and terminated alike shares current within a few percent, and a conductor that carries noticeably more than its share is the one with a loose termination, a shorter length, or a different route; the tolerance is set to catch those without failing a set for the small differences that lug resistance alone produces, and a tighter tolerance suits a set near its ampacity where any imbalance leaves one conductor overloaded. {note}
−## Large conductors have a minimum bend radius that, if not respected, damages the insulation and the strand geometry; for non-shielded conductors this is typically eight times the overall conductor diameter. {note}
+### A parallel set whose current balance exceeds the tolerance shall not be accepted until the Contractor has found and corrected the cause and repeated the test, and the cost of the correction and of every repeated test shall be borne by the Contractor.
−## Conductor routing, raceway placement, and pull-box locations are shown on the drawings because they are spatial arrangements that can never be reduced to a datasheet field. {note}
+### Where the neutral current test is selected, the neutral current of each feeder serving nonlinear load shall be measured with a true-rms instrument under the load in place at the time of the test, and shall be recorded with the phase currents and the load condition.
−## Conductors shall not be bent to a radius smaller than the minimum bend radius published by the conductor manufacturer, and in no case smaller than eight times the overall conductor diameter for non-shielded conductors.
+### The testing organization, its instruments, the safety practice, the deficiency process, and the compiled report shall be as [[sync/electrical-acceptance-testing]] requires, and the tests of this standard shall be recorded in that report.
−## Conductor pulling tension and sidewall pressure shall not exceed the manufacturer's published limits; pulling lubricant listed for the conductor jacket shall be used on long or congested runs.
+# Installation {toc}
−## Service and feeder conductors shall be routed as shown on the drawings [[drawing: feeder routing plan]].
+## Service Conductor Installation {toc}
−## Pull boxes and junction boxes for service and feeder conductors shall be located as shown [[drawing: pull-box locations]].
+### Service conductors shall be pulled, trained, supported, and terminated as the Installation section of [[sync/conductors-and-cables]] requires for feeders, with the additional requirements of this article.
−# Testing {toc}
+### Service conductors shall be pulled only after the service raceway has been proved clear and sealed as [[sync/electrical-service-entrance]] requires, and the conductors shall not be pulled through a raceway that is open to the weather or that stands in water at the time of the pull.
−## Acceptance testing confirms conductor continuity and insulation integrity before energization; leaving these criteria out of the specification is a common omission that produces disputes at closeout. {note}
+### Service conductors shall be installed without a splice or a tap except where [[sync/electrical-service-entrance]] permits one, and each permitted splice shall be made with the connector selected under the Line-Side Splices and Terminations article.
−## Insulation resistance is measured with a megohmmeter (megger) applied at a DC test voltage appropriate to the conductor rating; a 600 V conductor is typically tested at 500 V DC, with a minimum acceptable value of 1 MΩ per 1000 V of test voltage. {note}
+### Service conductors at the service head shall extend the length [[sync/electrical-service-entrance]] requires for the utility's splice, and service conductors at an underground service point shall extend the length the serving utility's requirements state for its terminations.
−## Each service and feeder conductor shall be tested for continuity and correct phase identification before energization.
+### Where parallel sets of service conductors enter the service equipment, the conductors of each set shall be trained to their lugs with the same bending radius and the same length within the enclosure, and no conductor of the set shall be looped to take up a length difference.
−## Each service and feeder conductor shall be tested for insulation resistance with a megohmmeter before energization.
+## Vertical Runs {toc}
−## The insulation resistance test voltage shall be appropriate to the conductor voltage rating, and the measured insulation resistance shall be not less than 1 MΩ per 1000 V of applied test voltage.
+### Service conductors and feeders in a vertical raceway shall be supported at the top of the raceway and at intervals not exceeding those NFPA 70 Table 300.19(A) states for the conductor size and material, by a support method that NFPA 70 300.19(B) recognizes.
−## Conductors that fail to meet the minimum insulation resistance shall be investigated and repaired or replaced before energization.
+### A conductor hanging in a riser carries its own weight on the termination at the top unless it is supported, and a large conductor in a tall riser weighs enough to pull out of a lug or to deform its insulation at the top bushing; the table intervals shorten as the conductor grows for that reason. {note}
−## Test results, including test voltage, duration, and measured values, shall be recorded and submitted as a closeout document.
+## Feeder Installation {toc}
−```datasheet
−label: Insulation resistance test voltage
−type: radio
−options:
− - 500 V DC
− - 1000 V DC
−default: 500 V DC
−```
+### Each feeder shall be installed with all of its conductors, the phases, the neutral, and the equipment grounding conductor, in the same raceway or cable, except as the Parallel Conductor Sets article permits for a parallel set in more than one raceway, in accordance with NFPA 70 300.3(B).
−```datasheet
−label: Minimum acceptable insulation resistance
−type: range
−unit: "MΩ"
−min: 1
−max: 100
−step: 1
−default: 1
−```
+### Where a feeder is installed in a ferrous raceway or enters a ferrous enclosure, all of the conductors of the feeder, or one of each phase and the neutral of each parallel set, shall pass through the same raceway and the same enclosure opening, in accordance with NFPA 70 300.20.
−# Installation {toc}
+### Each feeder shall be identified at its supply end and its load end with the feeder designation shown on the feeder schedule, with the label furnished under [[sync/electrical-identification]].
−## Conductors shall not be installed in a raceway until the raceway is complete, secured, swabbed clean, and free of moisture and debris.
−
−## Conductors shall be installed with the pulling means and lubricant specified, and shall not be subjected to tension or sidewall pressure exceeding the manufacturer's limits.
−
−## Each conductor shall be identified at every termination, splice, and pull point by phase, feeder designation, and where required by color code consistent across the project.
−
−## Where ambient or bundling conditions at the actual installed location differ from those assumed in design, the Contractor shall notify the Engineer of Record before installation so the conductor size can be re-verified.
−
−## Splices and taps shall be made only in accessible enclosures using listed connectors, and shall not be made within conduit bodies that are not listed for splicing.
−
# Delivery, Storage, and Handling {toc}
−## Conductors shall be delivered on reels or in cartons with the manufacturer's labeling intact, identifying type, size, voltage rating, and temperature rating.
+## Service conductors and cables shall be delivered, stored, inspected at receipt, and handled as [[sync/conductors-and-cables]] requires for feeders, and the ends of every service conductor on a reel and at every interruption of a pull shall be sealed against moisture.
−## Conductor reels shall be stored on a clean, dry surface, protected from physical damage, and protected from prolonged exposure to sunlight unless the insulation is sunlight-resistant.
+## A reel of service conductor or cable with damaged insulation or wetted ends shall be set aside, and the affected length shall be cut out and removed or the reel replaced, at the Contractor's cost, before any of it is installed.
−## Conductor ends shall be sealed against moisture entry during storage and during interruptions in pulling.
−
# Warranty {toc}
−## The Contractor shall warrant the service and feeder conductor installation, including terminations, against defects in material and workmanship for a period of not less than one year from the date of Substantial Completion.
+## The Contractor shall warrant the service conductors, the parallel sets, the taps, and the transformer secondary conductors, including every splice and termination made under this standard, under the same terms and for the same period as the feeder conductor installation is warranted under [[sync/conductors-and-cables]].
−## Termination failures attributable to incorrect torque, incorrect connector selection, or aluminum-to-copper connection without AL/CU-listed connectors shall be corrected at no cost to the Owner within the warranty period.
+## A service conductor or a parallel set replaced under warranty shall be retested as the Testing section requires before it is reconnected, and shall be warranted for the remainder of the original period or for one year from the date of replacement, whichever ends later.
−```datasheet
−label: Warranty period
−type: range
−unit: "years"
−min: 1
−max: 5
−step: 1
−default: 1
−```
−
−# Spare Parts {toc}
−
−## The Contractor shall turn over to the Owner any unused full reels and the manufacturer's product data for the conductor types and connectors installed.
−
−## Where the project documents require attic stock, the Contractor shall provide spare connectors and lugs of each type and size used on service and feeder terminations.
−
−```datasheet
−label: Spare connector stock (each type/size)
−type: range
−unit: "%"
−min: 0
−max: 10
−step: 1
−default: 0
−```
+## Where the parties disagree whether a warranty-period failure of a termination results from workmanship, from the connector, or from a load the feeder was not sized for, the Engineer of Record shall make the initial determination.