2016AllStarTraining,Inc.

1

NEC 2017 Code Changes Chapter 3 - Wiring Methods and Materials

Changes from the 2014 code are highlighted in yellow. ARTICLE 300 - General Requirements for Wiring Methods and Materials PartI.GeneralRequirements

300.1Scope.

(A)AllWiringInstallations.Thisarticlecoversgeneralrequirementsforwiringmethodsand

materialsforallwiringinstallationsunlessmodifiedbyotherarticlesinChapter3.

(B)IntegralPartsofEquipment.Theprovisionsofthisarticlearenotintendedtoapplytothe

conductorsthatforman

integralpartofequipment,

suchasmotors,controllers,

motorcontrolcenters,or

factory-assembledcontrol

equipmentorlisted

utilizationequipment.

(C)MetricDesignatorsand

TradeSizes.Metric

designatorsandtradesizes

forconduit,tubing,andassociatedfittingsandaccessoriesshallbeasdesignatedinTable

300.1(C).

2016AllStarTraining,Inc.

2

300.2Limitations.

(A)Voltage.WiringmethodsspecifiedinChapter3shallbeusedfor1000volts,nominal,orless

wherenotspecificallylimitedinsomesectionofChapter3.Theyshallbepermittedforover

1000volts,nominal,wherespecificallypermittedelsewhereinthisCode.

(B)Temperature.Temperaturelimitationofconductorsshallbeinaccordancewith

310.15(A)(3).

300.3Conductors.

(A)SingleConductors.SingleconductorsspecifiedinTable310.104(A)shallonlybeinstalled

wherepartofarecognizedwiringmethodofChapter3.

Exception:Individualconductorsshallbepermittedwhereinstalledasseparateoverhead

conductorsinaccordancewith225.6.

(B)ConductorsoftheSameCircuit.Allconductorsofthesamecircuitand,whereused,the

groundedconductorandallequipmentgroundingconductorsandbondingconductors

shallbecontainedwithinthesameraceway,auxiliarygutter,cabletray,cablebusassembly,

trench,cable,orcord,unlessotherwisepermittedinaccordancewith300.3(B)(1)through

(B)(4).

(1)ParalleledInstallations.Conductorsshallbepermittedtoberuninparallelin

accordancewiththeprovisionsof310.10(H).Therequirementtorunallcircuit

conductorswithinthesameraceway,auxiliarygutter,cabletray,trench,cable,orcord

shallapplyseparatelytoeachportionoftheparalleledinstallation,andtheequipment

2016AllStarTraining,Inc.

3

groundingconductorsshallcomplywiththeprovisionsof250.122.Parallelrunsincable

trayshallcomplywiththeprovisionsof392.20(C).

Exception:Conductorsinstalledinnonmetallicracewaysrunundergroundshallbepermittedto

bearrangedasisolatedphase,neutral,andgroundedconductorinstallations.Theraceways

shallbeinstalledincloseproximity,andtheisolatedphase,neutral,andgrounded

conductorsshallcomplywiththeprovisionsof300.20(B).

(2)GroundingandBondingConductors.Equipmentgroundingconductorsshallbe

permittedtobeinstalledoutsidearacewayorcableassemblywhereinaccordancewith

theprovisionsof250.130(C)forcertainexistinginstallationsorinaccordancewith

250.134(B),ExceptionNo.2,fordccircuits.Equipmentbondingconductorsshallbe

permittedtobeinstalledontheoutsideofracewaysinaccordancewith250.102(E).

(3)NonferrousWiringMethods.Conductorsinwiringmethodswithanonmetallicor

othernonmagneticsheath,whererunindifferentraceways,auxiliarygutters,cable

trays,trenches,cables,orcords,shallcomplywiththeprovisionsof300.20(B).

Conductorsinsingle-conductorTypeMIcablewithanonmagneticsheathshallcomply

withtheprovisionsof332.31.Conductorsofsingle-conductorTypeMCcablewitha

nonmagneticsheathshallcomplywiththeprovisionsof330.31,330.116,and300.20(B).

(4)Column-WidthPanelboardEnclosures.Whereanauxiliarygutterrunsbetweena

column-widthpanelboardandapullbox,andthepullboxincludesneutralterminations,

theneutralconductorsofcircuitssuppliedfromthepanelboardshallbepermittedto

originateinthepullbox.

2016AllStarTraining,Inc.

4

(C)ConductorsofDifferentSystems.

(1)1000Volts,Nominal,orLess.Conductorsofacanddccircuits,rated1000volts,

nominal,orless,shallbepermittedtooccupythesameequipmentwiringenclosure,

cable,orraceway.Allconductorsshallhaveaninsulationratingequaltoatleastthe

maximumcircuitvoltageappliedtoanyconductorwithintheenclosure,cable,or

raceway.Secondarywiringtoelectric-dischargelampsof1000voltsorless,ifinsulated

forthesecondaryvoltageinvolved,shallbepermittedtooccupythesameluminaire,

sign,oroutlinelightingenclosureasthebranch-circuitconductors.

InformationalNoteNo.1:See725.136(A)forClass2andClass3circuitconductors.

InformationalNoteNo.2:See690.4(B)forphotovoltaicsourceandoutputcircuits.

(2)Over1000Volts,Nominal.Conductorsofcircuitsratedover1000volts,nominal,

shallnotoccupythesameequipmentwiringenclosure,cable,orracewaywith

conductorsofcircuitsrated1000volts,nominal,orlessunlessotherwisepermittedin

300.3(C)(2)(a)through300.3(C)(2)(d).

(a)Primaryleadsofelectric-dischargelampballastsinsulatedfortheprimaryvoltageof

theballast,wherecontainedwithintheindividualwiringenclosure,shallbepermitted

tooccupythesameluminaire,sign,oroutlinelightingenclosureasthebranch-circuit

conductors.

(b)Excitation,control,relay,andammeterconductorsusedinconnectionwithany

individualmotororstartershallbepermittedtooccupythesameenclosureasthe

motor-circuitconductors.

2016AllStarTraining,Inc.

5

(c)Inmotors,transformers,switchgear,switchboards,controlassemblies,andsimilar

equipment,conductorsofdifferentvoltageratingsshallbepermitted.

(d)Inmanholes,iftheconductorsofeachsystemarepermanentlyandeffectively

separatedfromtheconductorsoftheothersystemsandsecurelyfastenedtoracks,

insulators,orotherapprovedsupports,conductorsofdifferentvoltageratingsshallbe

permitted.

Conductorshavingnonshieldedinsulationandoperatingatdifferentvoltagelevelsshallnot

occupythesameenclosure,cable,orraceway.

300.4ProtectionAgainstPhysicalDamage.Wheresubjecttophysicaldamage,conductors,

raceways,andcablesshallbeprotected.

InformationalNote:Minordamagetoaraceway,cablearmor,orcableinsulationdoesnot

necessarilyviolatetheintegrityofeitherthecontainedconductorsortheconductors’

insulation.

(A)CablesandRacewaysThroughWoodMembers.

(1)BoredHoles.Inbothexposedandconcealedlocations,whereacable-orraceway-

typewiringmethodisinstalledthroughboredholesinjoists,rafters,orwoodmembers,

holesshallbeboredsothattheedgeoftheholeisnotlessthan32mm(11∕4in.)from

thenearestedgeofthewoodmember.Wherethisdistancecannotbemaintained,the

cableorracewayshallbeprotectedfrompenetrationbyscrewsornailsbyasteel

plate(s)orbushing(s),atleast1.6mm(1∕16in.)thick,andofappropriatelengthand

widthinstalledtocovertheareaofthewiring.

2016AllStarTraining,Inc.

6

ExceptionNo.1:Steelplatesshallnotberequiredtoprotectrigidmetalconduit,intermediate

metalconduit,rigidnonmetallicconduit,orelectricalmetallictubing.

ExceptionNo.2:Alistedandmarkedsteelplatelessthan1.6mm(1∕16in.)thickthatprovides

equalorbetterprotectionagainstnailorscrewpenetrationshallbepermitted.

(2)NotchesinWood.Wherethereisnoobjectionbecauseofweakeningthebuilding

structure,inbothexposedandconcealedlocations,cablesorracewaysshallbe

permittedtobelaidinnotchesinwoodstuds,joists,rafters,orotherwoodmembers

wherethecableorracewayatthosepointsisprotectedagainstnailsorscrewsbya

steelplateatleast1.6mm(1∕16in.)thick,andofappropriatelengthandwidth,

installedtocovertheareaofthewiring.Thesteelplateshallbeinstalledbeforethe

buildingfinishisapplied.

ExceptionNo.1:Steelplatesshallnotberequiredtoprotectrigidmetalconduit,intermediate

metalconduit,rigidnonmetallicconduit,orelectricalmetallictubing.

ExceptionNo.2:Alistedandmarkedsteelplatelessthan1.6mm(1∕16in.)thickthatprovides

equalorbetterprotectionagainstnailorscrewpenetrationshallbepermitted.

(B)Nonmetallic-SheathedCablesandElectricalNonmetallicTubingThroughMetalFraming

Members.

(1)Nonmetallic-SheathedCable.Inbothexposedandconcealedlocationswhere

nonmetallic-sheathedcablespassthrougheitherfactory-orfield-punched,cut,or

drilledslotsorholesinmetalmembers,thecableshallbeprotectedbylistedbushings

2016AllStarTraining,Inc.

7

orlistedgrommetscoveringallmetaledgesthataresecurelyfastenedintheopening

priortoinstallationofthecable.

(2)Nonmetallic-SheathedCableandElectricalNonmetallicTubing.Wherenailsor

screwsarelikelytopenetratenonmetallic-sheathedcableorelectricalnonmetallic

tubing,asteelsleeve,steelplate,orsteelclipnotlessthan1.6mm(1∕16in.)in

thicknessshallbeusedtoprotectthecableortubing.

Exception:Alistedandmarkedsteelplatelessthan1.6mm(1∕16in.)thickthatprovidesequal

orbetterprotectionagainstnailorscrewpenetrationshallbepermitted.

(C)CablesThroughSpacesBehindPanelsDesignedtoAllowAccess.Cablesorraceway-type

wiringmethods,installedbehindpanelsdesignedtoallowaccess,shallbesupportedaccording

totheirapplicablearticles.

(D)CablesandRacewaysParalleltoFramingMembersandFurringStrips.Inbothexposedand

concealedlocations,whereacable-orraceway-typewiringmethodisinstalledparallelto

framingmembers,suchasjoists,rafters,orstuds,orisinstalledparalleltofurringstrips,the

cableorracewayshallbeinstalledandsupportedsothatthenearestoutsidesurfaceofthe

cableorracewayisnotlessthan32mm(11∕4in.)fromthenearestedgeoftheframing

memberorfurringstripswherenailsorscrewsarelikelytopenetrate.Wherethisdistance

cannotbemaintained,thecableorracewayshallbeprotectedfrompenetrationbynailsor

screwsbyasteelplate,sleeve,orequivalentatleast1.6mm(1∕16in.)thick.

2016AllStarTraining,Inc.

8

ExceptionNo.1:Steelplates,sleeves,ortheequivalentshallnotberequiredtoprotectrigid

metalconduit,intermediatemetalconduit,rigidnonmetallicconduit,orelectricalmetallic

tubing.

ExceptionNo.2:Forconcealedworkinfinishedbuildings,orfinishedpanelsforprefabricated

buildingswheresuchsupportingisimpracticable,itshallbepermissibletofishthecables

betweenaccesspoints.

ExceptionNo.3:Alistedandmarkedsteelplatelessthan1.6mm(1∕16in.)thickthatprovides

equalorbetterprotectionagainstnailorscrewpenetrationshallbepermitted.

(E)Cables,Raceways,orBoxesInstalledinorUnderRoofDecking.Acable,raceway,orbox,

installedinexposedorconcealedlocationsundermetal-corrugatedsheetroofdecking,shallbe

installedandsupportedsothereisnotlessthan38mm(11∕2in.)measuredfromthelowest

surfaceoftheroofdeckingtothetopofthecable,raceway,orbox.Acable,raceway,orbox

shallnotbeinstalledinconcealedlocationsinmetal-corrugated,sheetdecking–typeroof.

InformationalNote:Roofdeckingmaterialisoftenrepairedorreplacedaftertheinitial

racewayorcablingandroofinginstallationandmaybepenetratedbythescrewsorother

mechanicaldevicesdesignedtoprovide“holddown”strengthofthewaterproofmembraneor

roofinsulatingmaterial.

Exception:Rigidmetalconduitandintermediatemetalconduitshallnotberequiredtocomply

with300.4(E).

2016AllStarTraining,Inc.

9

(F)CablesandRacewaysInstalledinShallowGrooves.Cableorraceway-typewiringmethods

installedinagroove,tobecoveredbywallboard,siding,paneling,carpeting,orsimilar

finish,shallbeprotectedby1.6mm(1∕16in.)thicksteelplate,sleeve,orequivalentorbynot

lessthan32-mm(11∕4-in.)freespaceforthefulllengthofthegrooveinwhichthecableor

racewayisinstalled.

ExceptionNo.1:Steelplates,sleeves,ortheequivalentshallnotberequiredtoprotectrigid

metalconduit,intermediatemetalconduit,rigidnonmetallicconduit,orelectricalmetallic

tubing.

ExceptionNo.2:Alistedandmarkedsteelplatelessthan1.6mm(1∕16in.)thickthatprovides

equalorbetterprotectionagainstnailorscrewpenetrationshallbepermitted.

(G)InsulatedFittings.Whereracewayscontain4AWGorlargerinsulatedcircuitconductors,

andtheseconductorsenteracabinet,abox,anenclosure,oraraceway,theconductors

shallbeprotectedbyanidentifiedfittingprovidingasmoothlyroundedinsulatingsurface,

unlesstheconductorsareseparatedfromthefittingorracewaybyidentifiedinsulating

materialthatissecurelyfastenedinplace.

Exception:Wherethreadedhubsorbossesthatareanintegralpartofacabinet,box,enclosure,

orracewayprovideasmoothlyroundedorflaredentryforconductors.

2016AllStarTraining,Inc.

10

Conduitbushingsconstructedwhollyofinsulatingmaterialshallnotbeusedtosecureafitting

orraceway.Theinsulatingfittingorinsulatingmaterialshallhaveatemperatureratingnotless

thantheinsulationtemperatureratingoftheinstalledconductors.

(H)StructuralJoints.Alistedexpansion/deflectionfittingorotherapprovedmeansshallbe

usedwherearacewaycrossesastructuraljointintendedforexpansion,contractionor

deflection,usedinbuildings,bridges,parkinggarages,orotherstructures.

300.5UndergroundInstallations.

(A)MinimumCoverRequirements.Direct-buriedcable,conduit,orotherracewaysshallbe

installedtomeettheminimumcoverrequirementsofTable300.5.

(B)WetLocations.Theinteriorofenclosuresorracewaysinstalledundergroundshallbe

consideredtobeawetlocation.Insulatedconductorsandcablesinstalledintheseenclosures

orracewaysinundergroundinstallationsshallcomplywith310.10(C).

(C)UndergroundCablesandConductorsUnderBuildings.Undergroundcableandconductors

installedunderabuildingshallbeinaraceway.

ExceptionNo.1:TypeMIcableshallbepermittedunderabuildingwithoutinstallationina

racewaywhereembeddedinconcrete,fill,orothermasonryinaccordancewith332.10(6)orin

undergroundrunswheresuitablyprotectedagainstphysicaldamageandcorrosiveconditionsin

accordancewith332.10(10).

ExceptionNo.2:TypeMCcablelistedfordirectburialorconcreteencasementshallbe

permittedunderabuildingwithoutinstallationinaracewayinaccordancewith330.10(A)(5)

andinwetlocationsinaccordancewith330.10(A)(11).

2016AllStarTraining,Inc.

11

(D)ProtectionfromDamage.Direct-buriedconductorsandcablesshallbeprotectedfrom

damageinaccordancewith300.5(D)(1)through(D)(4).

(1)EmergingfromGrade.Direct-buriedconductorsandcablesemergingfromgrade

andspecifiedincolumns1and4ofTable300.5shallbeprotectedbyenclosuresor

racewaysextendingfromtheminimumcoverdistancebelowgraderequiredby300.5(A)

toapointatleast2.5m(8ft)abovefinishedgrade.Innocaseshalltheprotectionbe

requiredtoexceed450mm(18in.)belowfinishedgrade.

(2)ConductorsEnteringBuildings.Conductorsenteringabuildingshallbeprotectedto

thepointofentrance.

(3)ServiceConductors.Undergroundserviceconductorsthatarenotencasedin

concreteandthatareburied450mm(18in.)ormorebelowgradeshallhavetheir

locationidentifiedbyawarningribbonthatisplacedinthetrenchatleast300mm(12

in.)abovetheundergroundinstallation.

(4)EnclosureorRacewayDamage.Wheretheenclosureorracewayissubjectto

physicaldamage,theconductorsshallbeinstalledinelectricalmetallictubing,rigid

metalconduit,intermediatemetalconduit,RTRC-XW,Schedule80PVCconduit,or

equivalent.

(E)SplicesandTaps.Direct-buriedconductorsorcablesshallbepermittedtobesplicedor

tappedwithouttheuseofspliceboxes.Thesplicesortapsshallbemadeinaccordancewith

110.14(B).

(F)Backfill.Backfillthatcontainslargerocks,pavingmaterials,cinders,largeorsharplyangular

substances,orcorrosivematerialshallnotbeplacedinanexcavationwherematerialsmay

2016AllStarTraining,Inc.

12

damageraceways,cables,conductors,orothersubstructuresorpreventadequatecompaction

offillorcontributetocorrosionofraceways,cables,orothersubstructures.Wherenecessary

topreventphysicaldamagetotheraceway,cable,orconductor,protectionshallbeprovidedin

theformofgranularorselectedmaterial,suitablerunningboards,suitablesleeves,orother

approvedmeans.

(G)RacewaySeals.Conduitsorracewaysthroughwhichmoisturemaycontactlivepartsshall

besealedorpluggedateitherorbothends.Spareorunusedracewaysshallalsobesealed.

Sealantsshallbeidentifiedforusewiththecableinsulation,conductorinsulation,bare

conductor,shield,orothercomponents.

InformationalNote:Presenceofhazardousgasesorvaporsmayalsonecessitatesealingof

undergroundconduitsorracewaysenteringbuildings.

(H)Bushing.Abushing,orterminalfitting,withanintegralbushedopeningshallbeusedatthe

endofaconduitorotherracewaythatterminatesundergroundwheretheconductorsorcables

emergeasadirectburialwiringmethod.Asealincorporatingthephysicalprotection

characteristicsofabushingshallbepermittedtobeusedinlieuofabushing.

2016AllStarTraining,Inc.

13

(I)ConductorsoftheSameCircuit.Allconductorsofthesamecircuitand,whereused,the

groundedconductorandallequipmentgroundingconductorsshallbeinstalledinthesame

racewayorcableorshallbeinstalledincloseproximityinthesametrench.

2016AllStarTraining,Inc.

14

ExceptionNo.1:Conductorsshallbepermittedtobeinstalledinparallelinraceways,

multiconductorcables,ordirect-buriedsingleconductorcables.Eachracewayormulticonductor

cableshallcontainallconductorsofthesamecircuit,includingequipmentgrounding

conductors.Eachdirect-buriedsingleconductorcableshallbelocatedincloseproximityinthe

trenchtotheothersingleconductorcablesinthesameparallelsetofconductorsinthecircuit,

includingequipmentgroundingconductors.

ExceptionNo.2:Isolatedphase,polarity,groundedconductor,andequipmentgroundingand

bondingconductorinstallationsshallbepermittedinnonmetallicracewaysorcableswitha

nonmetalliccoveringornonmagneticsheathincloseproximitywhereconductorsareparalleled

aspermittedin310.10(H),andwheretheconditionsof300.20(B)aremet.

(J)EarthMovement.Wheredirect-buriedconductors,raceways,orcablesaresubjectto

movementbysettlementorfrost,direct-buriedconductors,raceways,orcablesshallbe

arrangedsoastopreventdamagetotheenclosedconductorsortoequipmentconnectedto

theraceways.

InformationalNote:Thissectionrecognizes“S”loopsinundergrounddirectburialcablesand

conductorstoracewaytransitions,expansionfittingsinracewayriserstofixedequipment,and,

generally,theprovisionofflexibleconnectionstoequipmentsubjecttosettlementorfrost

heaves.

2016AllStarTraining,Inc.

15

(K)DirectionalBoring.Cablesorracewaysinstalledusingdirectionalboringequipmentshallbe

approvedforthepurpose.

300.6ProtectionAgainstCorrosionandDeterioration.Raceways,cabletrays,cablebus,

auxiliarygutters,cablearmor,boxes,cablesheathing,cabinets,elbows,couplings,fittings,

supports,andsupporthardwareshallbeofmaterialssuitablefortheenvironmentinwhich

theyaretobeinstalled.

(A)FerrousMetalEquipment.Ferrousmetalraceways,cabletrays,cablebus,auxiliarygutters,

cablearmor,boxes,cablesheathing,cabinets,metalelbows,couplings,nipples,fittings,

supports,andsupporthardwareshallbesuitablyprotectedagainstcorrosioninsideandoutside

(exceptthreadsatjoints)byacoatingofapprovedcorrosion-resistantmaterial.Where

corrosionprotectionisnecessaryandtheconduitisthreadedinthefield,thethreadsshallbe

coatedwithanapprovedelectricallyconductive,corrosion-resistantcompound.

InformationalNote:Field-cutthreadsarethosethreadsthatarecutinconduit,elbows,or

nipplesanywhereotherthanatthefactorywheretheproductislisted.

Exception:Stainlesssteelshallnotberequiredtohaveprotectivecoatings.

(1)ProtectedfromCorrosionSolelybyEnamel.Whereprotectedfromcorrosionsolely

byenamel,ferrousmetalraceways,cabletrays,cablebus,auxiliarygutters,cablearmor,

boxes,cablesheathing,cabinets,metalelbows,couplings,nipples,fittings,supports,

andsupporthardwareshallnotbeusedoutdoorsorinwetlocationsasdescribedin

300.6(D).

2016AllStarTraining,Inc.

16

(2)OrganicCoatingsonBoxesorCabinets.Whereboxesorcabinetshaveanapproved

systemoforganiccoatingsandaremarked“Raintight,”“Rainproof,”or“OutdoorType,”

theyshallbepermittedoutdoors.

(3)InConcreteorinDirectContactwiththeEarth.Ferrousmetalraceways,cable

armor,boxes,cablesheathing,cabinets,elbows,couplings,nipples,fittings,supports,

andsupporthardwareshallbepermittedtobeinstalledinconcreteorindirectcontact

withtheearth,orinareassubjecttoseverecorrosiveinfluenceswheremadeof

materialapprovedforthecondition,orwhereprovidedwithcorrosionprotection

approvedforthecondition.

(B)AluminumMetalEquipment.Aluminumraceways,cabletrays,cablebus,auxiliarygutters,

cablearmor,boxes,cablesheathing,cabinets,elbows,couplings,nipples,fittings,supports,and

supporthardwareembeddedorencasedinconcreteorindirectcontactwiththeearthshallbe

providedwithsupplementarycorrosionprotection.

(C)NonmetallicEquipment.Nonmetallicraceways,cabletrays,cablebus,auxiliarygutters,

boxes,cableswithanonmetallicouterjacketandinternalmetalarmororjacket,cable

sheathing,cabinets,elbows,couplings,nipples,fittings,supports,andsupporthardwareshall

bemadeofmaterialapprovedfortheconditionandshallcomplywith(C)(1)and(C)(2)as

applicabletothespecificinstallation.

(1)ExposedtoSunlight.Whereexposedtosunlight,thematerialsshallbelistedas

sunlightresistantorshallbeidentifiedassunlightresistant.

2016AllStarTraining,Inc.

17

(2)ChemicalExposure.Wheresubjecttoexposuretochemicalsolvents,vapors,

splashing,orimmersion,materialsorcoatingsshalleitherbeinherentlyresistantto

chemicalsbasedontheirlistingorbeidentifiedforthespecificchemicalreagent.

(D)IndoorWetLocations.Inportionsofdairyprocessingfacilities,laundries,canneries,and

otherindoorwetlocations,andinlocationswherewallsarefrequentlywashedorwhere

therearesurfacesofabsorbentmaterials,suchasdamppaperorwood,theentirewiring

system,whereinstalledexposed,includingallboxes,fittings,raceways,andcableused

therewith,shallbemountedsothatthereisatleasta6-mm(1∕4-in.)airspacebetweenitand

thewallorsupportingsurface.

Exception:Nonmetallicraceways,boxes,andfittingsshallbepermittedtobeinstalledwithout

theairspaceonaconcrete,masonry,tile,orsimilarsurface.

InformationalNote:Ingeneral,areaswhereacidsandalkalichemicalsarehandledandstored

maypresentsuchcorrosiveconditions,particularlywhenwetordamp.Severecorrosive

conditionsmayalsobepresentinportionsofmeatpackingplants,tanneries,gluehouses,and

somestables;ininstallationsimmediatelyadjacenttoaseashoreandswimmingpoolareas;in

areaswherechemicaldeicersareused;andinstoragecellarsorroomsforhides,casings,

fertilizer,salt,andbulkchemicals.

300.7RacewaysExposedtoDifferentTemperatures.

(A)Sealing.Whereportionsofaracewayorsleeveareknowntobesubjectedtodifferent

temperatures,andwherecondensationisknowntobeaproblem,asincoldstorageareasof

2016AllStarTraining,Inc.

18

buildingsorwherepassingfromtheinteriortotheexteriorofabuilding,theracewayorsleeve

shallbefilledwithanapprovedmaterialtopreventthecirculationofwarmairtoacolder

sectionoftheracewayorsleeve.Anexplosionproofsealshallnotberequiredforthispurpose.

(B)Expansion,Expansion-Deflection,andDeflectionFittings.Racewaysshallbeprovidedwith

expansion,expansiondeflection,ordeflectionfittingswherenecessarytocompensatefor

thermalexpansion,deflection,andcontraction.

InformationalNote:Table352.44andTable355.44providetheexpansioninformationfor

polyvinylchloride(PVC)andforreinforcedthermosettingresinconduit(RTRC),respectively.A

nominalnumberforsteelconduitcanbedeterminedbymultiplyingtheexpansionlengthin

Table352.44by0.20.Thecoefficientofexpansionforsteelelectricalmetallictubing,

intermediatemetalconduit,andrigidmetalconduitis1.170×10-5(0.0000117mmpermmof

conduitforeach°Cintemperaturechange)[0.650×10-5(0.0000065in.perinchofconduitfor

each°Fintemperaturechange)].Anominalnumberforaluminumconduitandaluminum

electricalmetallictubingcanbedeterminedbymultiplyingtheexpansionlengthinTable

352.44by0.40.Thecoefficientofexpansionforaluminumelectricalmetallictubingand

aluminumrigidmetalconduitis2.34×10-5(0.0000234mmpermmofconduitforeach°Cin

temperaturechange)[1.30×10-5(0.000013in.perinchofconduitforeach°Fintemperature

change)].

2016AllStarTraining,Inc.

19

300.8InstallationofConductorswithOtherSystems.Racewaysorcabletrayscontaining

electricalconductorsshallnotcontainanypipe,tube,orequalforsteam,water,air,gas,

drainage,oranyserviceotherthanelectrical.

300.9RacewaysinWetLocationsAbovegrade.Whereracewaysareinstalledinwetlocations

abovegrade,theinterioroftheseracewaysshallbeconsideredtobeawetlocation.Insulated

conductorsandcablesinstalledinracewaysinwetlocationsabovegradeshallcomplywith

310.10(C).

300.10ElectricalContinuityofMetalRacewaysandEnclosures.Metalraceways,cablearmor,

andothermetalenclosuresforconductorsshallbemetallicallyjoinedtogetherintoa

continuouselectricalconductorandshallbeconnectedtoallboxes,fittings,andcabinetssoas

toprovideeffectiveelectricalcontinuity.UnlessspecificallypermittedelsewhereinthisCode,

racewaysandcableassembliesshallbemechanicallysecuredtoboxes,fittings,cabinets,and

otherenclosures.

ExceptionNo.1:Shortsectionsofracewaysusedtoprovidesupportorprotectionofcable

assembliesfromphysicaldamageshallnotberequiredtobemadeelectricallycontinuous.

ExceptionNo.2:Equipmentenclosurestobeisolated,aspermittedby250.96(B),shallnotbe

requiredtobemetallicallyjoinedtothemetalraceway.

300.11SecuringandSupporting.

(A)SecuredinPlace.Raceways,cableassemblies,boxes,cabinets,andfittingsshallbesecurely

fastenedinplace.

2016AllStarTraining,Inc.

20

(B)WiringSystemsInstalledAboveSuspendedCeilings.Supportwiresthatdonotprovide

securesupportshallnotbepermittedasthesolesupport.Supportwiresandassociated

fittingsthatprovidesecuresupportandthatareinstalledinadditiontotheceilinggridsupport

wiresshallbepermittedasthesolesupport.Whereindependentsupportwiresareused,

theyshallbesecuredatbothends.Cablesandracewaysshallnotbesupportedbyceilinggrids.

(1)Fire-RatedAssemblies.Wiringlocatedwithinthecavityofafire-ratedfloor–ceiling

orroof–ceilingassemblyshallnotbesecuredto,orsupportedby,theceilingassembly,

includingtheceilingsupportwires.Anindependentmeansofsecuresupportshallbe

providedandshallbepermittedtobeattachedtotheassembly.Whereindependent

supportwiresareused,theyshallbedistinguishablebycolor,tagging,orothereffective

meansfromthosethatarepartofthefire-rateddesign.

Exception:Theceilingsupportsystemshallbepermittedtosupportwiringandequipmentthat

havebeentestedaspartofthefire-ratedassembly.

InformationalNote:Onemethodofdeterminingfireratingistestinginaccordancewith

ANSI/ASTME119-2015,MethodforFireTestsofBuildingConstructionandMaterials.

(2)Non–Fire-RatedAssemblies.Wiringlocatedwithinthecavityofanon–fire-rated

floor–ceilingorroof–ceilingassemblyshallnotbesecuredto,orsupportedby,the

ceilingassembly,includingtheceilingsupportwires.Anindependentmeansofsecure

supportshallbeprovidedandshallbepermittedtobeattachedtotheassembly.Where

2016AllStarTraining,Inc.

21

independentsupportwiresareused,theyshallbedistinguishablebycolor,tagging,or

othereffectivemeans.

Exception:Theceilingsupportsystemshallbepermittedtosupportbranch-circuitwiringand

associatedequipmentwhereinstalledinaccordancewiththeceilingsystemmanufacturer’s

instructions.

(C)RacewaysUsedasMeansofSupport.Racewaysshallbeusedonlyasameansofsupport

forotherraceways,cables,ornonelectricalequipmentunderanyofthefollowingconditions:

(1)Wheretheracewayormeansofsupportisidentifiedasameansofsupport

(2)Wheretheracewaycontainspowersupplyconductorsforelectricallycontrolled

equipmentandisusedtosupportClass2circuitconductorsorcablesthataresolelyfor

thepurposeofconnectiontotheequipmentcontrolcircuits

(3)Wheretheracewayisusedtosupportboxesorconduitbodiesinaccordancewith

314.23ortosupportluminairesinaccordancewith410.36(E)

(D)CablesNotUsedasMeansofSupport.Cablewiringmethodsshallnotbeusedasameans

ofsupportforothercables,raceways,ornonelectricalequipment.