networking: ch. 11 technical information - barr- · pdf filetechnical information thermal...

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Subjecttochangewithoutnotice PH763-422-2661•FX763-422-2588•hoffmanonline.com ©2010PentairTechnicalProducts

WhenselectingITcabinets,applicationandenvironmentareessentialconsiderations.Whilestandardservercabinetscanperformwellinenvironmentally-manageddatacenters,theruleschangewhenyoursensitiveequipmentmustendureharshconditionssuchasthefactoryfloor,remotelocationsorevenoutdoorenvironmentsinapplicationssuchastelecommunications.Noproviderisbetterequippedtodealwithprotectionintheharshrealityoftoday’sdemandingnetworkapplications,includingsolutionstailoredforNEMATypes4Xand12,closedlooptemperaturecontrolandseismicconditions.

THERMALEffectivethermalmanagementmaximizestheefficiencyandlifecycleofelectricalcomponents.Whileitiscriticaltodissipateandmanageheatbuild-up,itcanalsobenecessarytoaddheat.

Somekeyquestionsfordeterminingtheappropriatecoolingunitforyourapplication:

Whatsizeismyenclosure?Whichenclosuresurfacesallowheattransfer?WhattypeofsystemdoIneed?Suchas openlooporclosedloop.Whatismyenclosure’sinsulationRvalue?Ismyapplicationindoorsoroutdoors?Willthecoolingunitbemounted onthetop,sideorinsidetheenclosure?Keyequationfordatacentercooling: Watts=.316xCFMx∆T

Selectanenclosurethathasaratingappropriateforyourenvironmentandapplication.RatingsystemsfromNEMA,UL,CSA,IECandVDEdetermineanenclosure'sabilitytowithstandenvironmentalconditions.However,theseratingsdifferinimportantways.

STANDARDS

Technical informaTion

CHAPTER11

This document provided by Barr-Thorp Electric Co., Inc. 800-473-9123 www.barr-thorp.com

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chaPTer conTenTSChapterContents

Thermal ManagementHowtoDissipateExcessHeat-UnderstandingΔTandCFM. . . . . . 260ΔT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260CFM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .261

Solar Heat GainSolarHeatGain. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .262ExposuretoSolarRadiation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .262EffectofSurroundingLocation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .262EffectofEnclosureColorandFinish. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .262StandardizedTestEvaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .262EvaluationofSolarHeatGain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .262TheBenefitsofShieldingEnclosures. . . . . . . . . . . . . . . . . . . . . . . . . . . . 263

StandardsStandardsOrganizationSummaryandDirectoryOverview. . . . . . 264CE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264EnclosureTypeRatingvs.IPRating. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264NEMA,ULandCSARatings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265IPRatingDescriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265


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ThermalManagement

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NetworkingTechnical InformationThermal Management

HowtoDissipateExcessHeat-UnderstandingΔTandCFM

Whenitcomestocoolingadatacenter,oneequationiskeyCoolingnetworkequipmentrequiresbothcoldintakeairandairflow(CFM).Thesetwofactorsworkdirectlytodissipate,orcarryaway,theheatthatnetworkequipmentproduces.Whileincreasingeitherfactorwillincreasetheamountofheatthatisdissipated,therearelimitstoboth.Airthatistoocoldresultsinthermalexpansionandcondensationissues.Airflowthatistoohighresultsinacousticandphysicallimitations.Acoolingsystemthatreliesontoomuchofonlyoneofthesefactorsusuallyresultsinhighercapitalandoperatingcosts.Findinganidealbalancebetweencoldairandairflowallowsoptimalheatdissipation,protectingnetworkequipmentfromtheconsequencesofoverheating.

ΔTIntheaboveequations,ΔT,measuredindegreesFahrenheit,referstothedifferencebetweentheintakeairandexhaustair,ortheamountofheatthatiscarriedawaybythestreamofairexitingtheheatload.Agreatertemperaturedifferencesignifiesmoreheatbeingremoved.Whileitisdifficulttoconstantlydeliverthecoldestairtoallequipment—inparticular,equipmentinstalledinupperrackunits—datacentersthatmaintainarangebetween10and30FΔTcarryahighlevelofconfidencethatequipmentwilldissipatetheamountofheatthatitproduces,stayingwithinitsthermallimits.

• Theareabetween10and30degreesΔTrepresentscapablecoolinginatypicalwell-designeddatacenter.• Knowingtwoofthethreequantitiesallowsoperatorstosolveforthethird—inthisequation,knowingeitherwattsorCFMsolvesforΔT.

Forexample,9000wattsinadatacenterwithaΔTof20degreesrequires1425CFM.

More than 30 degrees ΔT can cause humidity and condensation issues.

30˚∆T25,000

20,000

15,000

10,000

5,000

0

Watts = .316 x CFM x ∆T (˚F)

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

2,200

2,400

CFM

Wat

ts 102030

10˚∆T

20˚∆T


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CFMAnotherwaytoincreasetheamountofheatdissipatedorremovedfromnetworkequipmentisbyincreasingtheairflow,expressedincubicfeetperminute(CFM).AnincreaseofCFM—theamountofairflowacrossagivenareainagiventime—resultsinincreasedheatremoval.CFMcanbeachievedthroughtheuseoffans.Thelargerthefan,themoreCFMitprovides.AnincreaseinRPM(thespeedatwhichthefancirculates)aswellasthesizeorquantityoffanbladesresultsinahigherCFM,butasthesefactorsincrease,sodoseveralothersthatcanbedetrimentaltotheequipmentindatacenters.Forexample,acousticnoiseisoneconsequenceofhighlevelsofCFM.Additionally,atveryhighCFM,physicalforcesalsocomeintoplaythatcancausedamagetoelectricalequipment.PlusthehighertheCFM,thehighertheupfrontcapitalcosts,aswellasongoingoperationalexpenses.

• Mostdatacentersoperatebetween10and20ΔT.UsingthisandtheCFMofthefan,thenecessaryquantityofcooling(watts)canbedetermined.

• Thesameequationalsoworksforequipmentoutsidethedatacenter.Again,theintakeaircanonlybesocoldandatacertainCFMbeforeotherissuesarise.

• Thebiggerthefan,themoreairflowthatmovesacrossequipment.Theamountofairflowandthetemperatureoftheairdeterminetheamountofheatdissipationthatcanoccur.

• CFMin=CFMoutonallpassivesystems.

• TotalCFMin=thesumofallequipment(servers)mountedinthecabinet.

An increase in fan size will increase acoustic noise at the same motor RPM.

30˚∆T

10˚∆T

20˚∆T

4" FanQuiet

4" Fan

6" Fan

10" Fan

102030

6000

5500

5000

4500

4000

3500

3000

2500

2000

1500

1000

500

0

4", 6", & 10" Cooling Fan Performance

0 25 50 75 100

125

150

175

200

225

250

275

300

325

350

375

400

425

450

475

500

525

550

575

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CFM

Wat

ts


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SolarHeatGain

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Solar Heat Gain

SolarHeatGainWhenevaluatingthethermalmanagementneedsofoutdoorelectricalenclosures,solarheatgainmustbeconsidered.Variablesthataffecttheenclosure’sinternaltemperatureriseincludetheamountofsolarexposure,enclosurecolorandmaterialtype,highestsustainedatmospherictemperature,heatbuild-upfrominternalcomponentsandheatreflectancefromthesurroundingenvironment.

ExposuretoSolarRadiationOvermuchoftheUnitedStates,theapproximatepeakvaluesofsolarradiationstrikingtheEarth’ssurfaceis97watts/ft.2andtheambientairtemperaturecanreach104F.Altitude,humidityandairpollutionhaveanimpactonthesevalues,evenmoresothanthelocation’slatitude.Inthehigh,dryclimatesofthesouthwest,solarradiationvaluesof111watts/ft.2andairtemperaturesgreaterthan104Fcanbereached.

Theextremeconditionstheenclosurewillbeexposedtoshouldbeidentified.Iftheinternalenclosuretemperatureisgreaterthantheoutdoor(ambient)temperature,windwillprovidegreaterheattransferandthuscooltheenclosure.But,becausethepresenceofwindcannotbeguaranteed,itisusuallynottakenintoaccountwhenestablishingaworst-caseevaluation.

EffectofSurroundingLocationReflectionofsolarenergyfromtheforegroundandsurroundingsurfacescanimpactthetotalamountofradiantexposurebyasmuchas30percent.

EffectofEnclosureColorandFinishThepercentofsolarenergyabsorbedbytheenclosuredependsonsurfacecolor,finishandtexture.Absorptionvaluesofthefinishwillincreasewithage.

StandardizedTestEvaluationTelcordiaNEBS™GR-487providesatestprocedureforevaluatingthesolarloadonelectrical/electronicenclosures.Thetestisrunwiththeinternalelectronicson,inanenvironmentallycontrolledroom,andthreesidesoftheenclosureareilluminateduniformlywithcontrolledbanksoflightstoameasuredsurfaceradiantvalueof70watts/ft.2Thetemperatureriseinsidetheenclosureaboveambientisaddedto115F(46C).Thistemperaturetotalmustnotexceedthelowest-ratedcomponentwithintheenclosure.

EvaluationofSolarHeatGainToevaluatetheheatloadonanenclosure,youmusttakeintoaccount:• Totalsurfaceareaoftheenclosure• Coloroftheenclosure• Internalheatload• Maximumallowableinternaltemperature• Maximumambienttemperature• Solarload

Examples:1. Whatamountofheatenergymustberemovedfroma24x

20x12(surfacearea=14ft.2)ANSI61grayenclosurelocatedoutdoorsandwithoutanyheatdissipatedinternally,tomaintaintheenclosuretemperatureequaltotheambient(temperaturerise=0degrees)?

Fromthechartbelow,at0Ftemperaturerisewefindthesolarloadisapproximately14watts/ft.214ft.2x14watts/ft.2=196watts.Thisistheheatenergythatmustberemovedtomaintaintheenclosuretemperatureatambient.

2. Ifthesameenclosurehasinternalequipmentdissipating200wattsofheat,whatistheamountofheatenergythatmustberemovedtomaintaintheenclosureatatemperatureriseof20 Fabovetheambienttemperature?

Fromthechartbelow,at20Ftemperaturerisewefindthesolarloadisapproximately6watts/ft.214ft.2x6watts/ft.2=84watts.

Alloftheinternallydissipatedheatof200wattsmustalsoberemoved.84watts+200watts=284watts.Thisisthetotalamountofheatenergythatmustberemovedtomaintaintheenclosureat20 Fabovetheambienttemperature.

3. WhatistheexpectedtemperatureriseabovetheambienttemperatureduetosolarheatgainforanenclosurewithANSI61grayfinish?

Fromthechartbelow,thetemperatureriseduetosolarheatloadcanbefoundbylocatingtheintersectionofthedatacurveforthegivenfinishandthe0SolarGeneratedHeatLoadaxis.ForANSI61Gray,thetemperatureriseduetosolarheatisabout40F.

Black

Gray

Light Color

White

Metallic

Solar Load Based on Color and Temperature Rise

0

10

20

30

40

50

∆T

(Inte

rnal

Tem

p. -

Am

bien

t Tem

p.) °

F

Solar Load (watts/ft2)5 10 20 3015 25


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TheBenefitsofShieldingEnclosures

Hoffman’sresearchontheeffectsofsolarradiationonenclosureshasshownthepositivebenefitsofutilizingshieldingtodecreasetemperaturerise.Shieldinghasbeenfoundtobeaneffective,low-costmethodofreducingsolarheatgaininoutdoorelectrical/electronicapplications.

A test to compare the shielding effect on internal temperature rise was performed on similar enclosures exposed to the sun. The enclosures are the same color (RAL 7035 light gray) and material. The enclosure on the left is unshielded; the enclosure on the right is shielded on top and applicable sides.

The results of the test show the enclosure with top and side shields to have approximately a 46 percent reduction in temperature compared to the unshielded enclosure. The reduction in temperature is approximately 25 percent with the solar top shield only. Hoffman offers top shields as an accessory for Hoffman COMLINE® Wall-Mount Enclosures. Hoffman can provide side shields as a customer-ordered modification.

Outside TemperatureTop and Side Shield

Shielding E�ectiveness

No ShieldSide Shield

75

85

95

105

115

3:00 a.m. 7:00 a.m. Noon 4:30 p.m.July 29, 1999

Tem

pera

ture

(°F)

enclosure Type Temperature (f) Temperature (c) Percent Temperature reductionUnshielded 119 48 —Top shield only 114 46 25Top and side shields 110 43 46


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Standards

StandardsOrganizationSummaryandDirectoryOverviewWhat’sinaRating?Asawayofstandardizingenclosureperformance,organizationslikeNEMA,UL,CSA,IECandVDEuseratingsystemstoidentifyanenclosure’sabilitytoresistexternalenvironmentalinfluences.Resistancetoeverythingfromdrippingliquidtohose-downtototalsubmersionisdefinedbytheratingssystems.Whiletheseratingsareallintendedtoprovideinformationtohelpyoumakeasafer,more-informedproductchoice,therearedifferencesamongthem.

NorthAmericanStandardsOrganizationsInNorthAmerica,NEMA,ULandCSAarethecommonlyrecognizedstandardsorganizations.Theirratingsarebasedonsimilarapplicationdescriptionsandexpectedperformance.ULandCSAbothrequireenclosuretestingbyqualifiedevaluatorsintheircertifiedlabs.Theyalsosendsiteinspectorstomakesureamanufactureradherestoprescribedmanufacturingmethodsandmaterialspecifications.NEMA,ontheotherhand,doesnotrequireindependenttestingandleavescompliancecompletelyuptothemanufacturer.

NorthAmericanenclosureratingsystemsalsoincludea4Xratingthatindicatescorrosionresistance.Thisratingisbasedontheenclosure’sabilitytowithstandprolongedexposuretosaltwaterspray.

Whilea4Xratingisagoodindicatorthatanenclosurecanresistcorrosion,itdoesnotprovideinformationonhowaspecificcorrosiveagentwillaffectagivenenclosurematerial.Itisbesttoconductafullanalysisofthespecificapplicationandenvironmenttodeterminethebestenclosurechoice.

InternationalStandardsOrganizationsLikeNEMA,IECdoesnotrequireindependenttestingandleavescompliancecompletelyuptothemanufacturer.Nevertheless,therearedifferencesinhowenclosureperformanceisinterpreted.Forexample,ULandCSAtestrequirementsspecifythatanenclosurefailsthewater-tighttestifevenasingledropofwaterenterstheenclosure.IntheIECstandardsforeachlevelofingressprotection(IP),acertainamountofwaterisallowedtoentertheenclosure.

IEC60529IPratingsdonotspecifyconstructionrequirementsordegreesofprotectionagainstcorrosiveatmospheres,riskofexplosionorconditionssuchasmoistureorcorrosivevapors.NEMATyperatings,ontheotherhand,dospecifyconstructionandperformancerequirementsformostenvironmentalconditions.Forthisreason,andbecausethetestsandevaluationsforothercharacteristicsarenotidentical,theIECenclosureclassificationdesignationscannotbeexactlyequatedwithNEMAenclosureTypenumbers.

CEForindustrialcontrolequipment,theCEMarkisnotintendedtobeappliedtoemptyenclosuresbecausesuchenclosuresareinactivecomponentsofafinalassembly.TheresponsibilityofensuringcompliancewithallapplicableEUdirectivesandharmonizedstandardsbelongswiththefinalequipmentmanufacturer.

EnclosureTypeRatingvs.IPRatingElectricalenclosuresareratedbyType(NEMA250/UL50,50E),and/orIPrating(IEC60529)baseduponthedegreeofprotectionprovided.TyperatingsandIPratingshaveonlythefollowingincommon:

1. Adegreeofprotectionforpersonsfromhazardouscomponentsinsidetheenclosure

2. Adegreeofprotectionforequipmentinsidetheenclosurefromingressofsolidforeignobjects,includingdust

3. Adegreeofprotectionforequipmentinsidetheenclosurefromingressofwater

NEMA250andUL50,50ETyperatingdocumentationdefinesadditionalrequirementsthataType-ratedenclosuremustmeet.Theseinclude:• Mechanicalimpactonenclosurewalls• Gasketagingandoilresistance• Corrosionresistance• Doorandcoverlatchingrequirements• Sheetmetalgaugeconstructionrequirements(UL50only)

ElectricalenclosuresthatcarryonlyanIPratinghavenotbeendesignedortestedtotheadditionalType-ratingrequirements.Forthisreason,andbecausethetestsandevaluationsforothercharacteristicsarenotidentical,theIPratingscannotbeexactlyequatedwithNEMAenclosureTypes.

ElectricalenclosuresmanufacturedbyHoffmanaretestedforandcarrybothTypeandIPratings.

FluidStaticsandDynamicComparisonofIngressWaterTests

Test Typeflow rate (gal./min.)

flow rate(l/min.)

nozzleDiameter in./mm

nozzlearea(sq. in.)

nozzleVelocity (ft./sec.)

equivalenthead (ft.)

equivalentPressure (psi)

massflow (lb./sec.)

Power(hp)

Total forceon VerticalPlate (lb.)

Type 3 45.00 170 1.000025.4

0.7854 18.38 5.25 2.274 6.256 0.060 3.5716

Type 4 65.00 246 1.00025.4

0.7854 26.55 10.85 4.744 9.037 0.180 7.4516

IPX5 3.30 12.5 0.24806.3

0.0483 21.93 7.46 3.235 0.459 0.006 0.3126

IPX6 26.42 100 0.492112.5

0.1902 44.55 30.82 13.357 3.672 0.206 5.0815


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NEMA,ULandCSARatings EnclosureTypeDescriptionsforNon-HazardousLocations

enclosureType nema Ul cSa

Indoor Type 1 Enclosures are intended for indoor use primarilyto provide a degree of protection against contactwith the enclosed equipment or locations whereunusual service conditions do not exist.

Indoor use primarily to provide protection againstcontact with the enclosed equipment and againsta limited amount of falling dirt.

General purpose enclosure. Protects againstaccidental contact with live parts.

Indoor Type 12 Enclosures are intended for indoor use primarily toprovide a degree of protection against dust, fallingdirt and dripping noncorrosive liquids.

Indoor use to provide a degree of protection againstdust, dirt, fiber flyings, dripping water and externalcondensation of noncorrosive liquids.

Indoor use; provides a degree of protection against circulatingdust, lint, fibers and flyings; dripping and light splashing ofnon-corrosive liquids; not provided with knockouts.

Indoor Type 12K Enclosures with knockouts are intended for indooruse primarily to provide a degree of protection againstdust, falling dirt and dripping noncorrosive liquids.

Indoor use to provide a degree of protection againstdust, dirt, fiber flyings, dripping water and externalcondensation of noncorrosive liquids.

Indoor use: provides a degree of protection against circulatingdust, lint, fibers and flyings; dripping and light splashingof noncorrosive liquids; not provided with knockouts.

Indoor Type 13 Enclosures are intended for indoor use primarily toprovide a degree of protection against dust, sprayingof water, oil and noncorrosive coolant.

Indoor use to provide a degree of protection againstlint, dust seepage, external condensation andspraying of water, oil and noncorrosive liquids.

Indoor use; provides a degree of protection against circulatingdust, lint, fibers and flyings; seepage and spraying ofnon-corrosive liquids, including oils and coolants.

Outdoor Type 3 Enclosures are intended for outdoor use primarily toprovide a degree of protection against windblown dust, rainand sleet; undamaged by the formation of ice on the enclosure.

Outdoor use to provide a degree of protection againstwindblown dust and windblown rain; undamaged bythe formation of ice on the enclosure.

Indoor or outdoor use; provides a degree of protection againstrain, snow and windblown dust; undamaged by the externalformation of ice on the enclosure.

Outdoor Type 3R Enclosures are intended for outdoor use primarily to provide adegree of protection against falling rain and sleet; undamagedby the formation of ice on the enclosure.

Outdoor use to provide a degree of protection againstfalling rain; undamaged by the formation of iceon the enclosure.

Indoor or outdoor use; provides a degree of protection againstrain and snow; undamaged by the external formationof ice on the enclosure.

Outdoor Type 3RX Enclosures are intended for outdoor use primarily toprovide a degree of protection against corrosion, falling rainand sleet; undamaged by the formation of ice on the enclosure.

Not specifically defined. Not specifically defined.

Outdoor Type 4 Enclosures are intended for indoor or outdoor use primarilyto provide a degree of protection against windblown dustand rain, splashing water and hose directed water;undamaged by the formation of ice on the enclosure.

Either indoor or outdoor use to provide a degreeof protection against falling rain, splashing waterand hose-directed water; undamaged by theformation of ice on the enclosure.

Indoor or outdoor use; provides a degree of protection againstrain, snow, windblown dust, splashing and hose-directedwater; undamaged by the external formation of ice on theenclosure.

Outdoor Type 4X Enclosures are intended for indoor or outdoor use primarilyto provide a degree of protection against corrosion,windblown dust and rain, splashing water and hose-directedwater; undamaged by the formation of ice on the enclosure.

Either indoor or outdoor use to provide a degree ofprotection against falling rain, splashing water andhose-directed water; undamaged by the formationof ice on the enclosure; resists corrosion.

Indoor or outdoor use; provides a degree of protection against rain,snow, windblown dust, splashing and hose-directed water;undamaged by the external formation of ice on the enclosure;resists corrosion.

Outdoor Type 6 Enclosures are intended for use indoors or outdoors whereoccasional submersion is encountered; limited depth;undamaged by the formation of ice on the enclosure.

Indoor or outdoor use to provide a degree of protection against entry of water during temporary submersion at a limited depth; undamaged by the external formation of ice on the enclosure.

Indoor or outdoor use; provides a degree of protection againstthe entry of water during temporary submersion at a limiteddepth. Undamaged by the external formation of ice on theenclosure; resists corrosion.

This material is reproduced with permission from NEMA. The preceding descriptions, however, are not intended to be complete representations of National Electrical Manufacturers Association standardsfor enclosures nor those of the Electrical and Electronic Manufacturers Association of Canada.This material is reproduced with permission from Underwriters Laboratories Inc. Enclosures for Electrical Equipment, UL 50, 50E and Industrial Control Panels, UL 508A.This material is reproduced with permission from the Canadian Standards Association.Underwriters Laboratories Inc. (UL) shall not be responsible for the use of or reliance upon a UL Standard by anyone. UL shall not incur any obligation or liability for damages, including consequential damages,arising out of or in connection with the use, interpretation of, or reliance upon a UL Standard.

IPRatingDescriptions ExampleRating

if 1st iP number is... and the 2nd ip number is... Then the iP rating is2 3 IP 2 3(protection against solid objects) (protection against liquids) An enclosure with this designation provides protection against touch with a finger, penetration of solid objects greater than 12mm, and spraying water.

FirstNumeral(SolidObjectsandDust)iP Protection of Persons Protection of equipment0 No Protection No Protection1 Protected against contact with large areas of the body (back of hand) Protected against objects over 50 mm in diameter2 Protected against contact with fingers Protected against solid objects over 12 mm in diameter3 Protected against tools and wires over 2.5 mm in diameter Protected against solid objects over 2.5 mm in diameter4 Protected against tools and wires over 1 mm in diameter Protected against solid objects over 1 mm in diameter5 Protected against tools and wires over 1 mm in diameter Protected against dust (limited ingress, no harmful deposit)6 Protected against tools and wires over 1 mm in diameter Totally protected against dust

SecondNumeral(Liquid)iP Protection of equipment0 No Protection1 Protected against vertically falling drops of water, e.g. condensation2 Protected against direct sprays of water up to 15 degrees from vertical3 Protected against sprays to 60 degrees from vertical4 Protected against water sprayed from all directions (limited ingress permitted)5 Protected against low-pressure jets of water from all directions (limited ingress permitted)6 Protected against strong jets of water7 Protected against the effects of immersion between 15 cm and 1 m8 Protected against long periods of immersion under pressure


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