nec 2017 code changes chapter 3 - wiring methods … 2017 code changes chapter 3 - wiring methods...
Post on 21-May-2018
231 Views
Preview:
TRANSCRIPT
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.
top related