Architectural Engineering Design Group

NewsletterMay2007ElectricalSystemsRulesofThumb

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ElectricalSystemsRulesofThumb

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ELECTRICALSYSTEMSRULESOFTHUMB:

1.ElectricalRoomRequirements

a. Onlargerfacilities,themainroomtypicallyneedstwodoors,oneateachendofroom(notdoubledoorsatonelocation).

b. Doorsmustopeninthedirectionofegressfromtheroom.c. Doorsmusthavepanichardware.d. RatedConstruction:Itisnottypicalthatthisroomberequiredtohavea1hour

rating.Iftheelectricalengineerneedsalargetransformer(atransformerwitharatingover112.5KVA)inthisroom,theyshouldnotifytheArchitectthattheroomwillberequiredtohavea1hourratingduetotheNationalElectricalCoderequirements.

2.ElectricalRoomSizingforTypicalFacilities(recreationcenters,multifamily,generalcommercial)

SizeofFacility

MainElecRoom RemoteElecRoomsRqd?

RemoteElecRoomSize Notes

020,000sf,onelevel

10x20 Typicallynot N/A (1)

20,00040,000sfmultilevels

15x20 Oneonmainlevelandoneper20,000sfonupperlevel(s)

8x10each (1)

+40,000sf 15x20 Oneachlevel,oneper20,000sfandspace200apart

8x10each (1)

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(1)Additionalremoteelectricalroomsshouldbeconsideredforbuildingswithdistinctspacelayoutswhichmaybenefitfromadditionallocalizeddistributionequipment.(i.e.Anindividualwingofbuildingthatisseparatedfromthemainbuildingbymultistoryopenatrium).

3.ExteriorServiceTransformer(notethatallspecificelectricalutilitytransformerrequirementsaretobecoordinatedwiththelocalutilityengineerfortheprojectasmostutilitycompaniesvarytheirrequirements)

a. Lessexpensiveiftransformerislocatednearelectricalroom.b. Formediumtolargefacilitiesanticipate8x8padsize.c. Provide36cleararoundthreesides,and12ofclearanceonfrontside.d. Typicallydriveupaccessisrequiredfortheutilitycompany.e. Itisdesirabletolocatetheelectricalroomonanexteriorwall,nearthefinal

utilitytransformerlocation.

4.Phone/dataRooms

a. Typicallyatleastoneperlevelofanybuildingtype.Cablecanberouted300fromdevicetoroom,soadditionalroomswouldberequiredforbuildingslongerthan300inanydirection.

b. RoomsizesvarybasedupontheITdepartmentsneeds,butanticipate10x10formaintelephoneroomsand6x6forremoterooms.

5.Wallsthroughoutthefacilitycontainingrecessedelectricalpanelboardsshouldbeaminimumof6deep.

LIGHTINGSYSTEMSRULESOFTHUMB:

1.Lightingis30%oftheoverallbuildingpowerusage.Savingsintheoverallwatts/sfusedforlightingcanhaveasignificantimpact.

2.Typical2x4lightingfixturespacingis8x10.

3.Wallmountedlightingfixturescanonlybemountedbelow68iftheyproject4orlessfromthewall.

4.Atypicalbuildingwillendupwithanoveralllightingloadof1.01.5wattspersquarefoot.

5.Energyefficiencyoftypicallamps

a. One32wattfluorescentT8hastheequivalentlightoutputtothree60wattincandescentALamps(thestandardhouseholdscrewinlamp)ortwo60watthalogenMR16lamps.

b. FluorescentHighOutputT5similarefficiencytotheT8fluorescentbutitssmallersizecanleadtomoreefficientfixturedesign.

c. MetalHalideisapproximately15%lessefficientthanfluorescent.d. LEDactuallyhasaverylowlightoutputperwatt.Itsoverallenergyefficiencyis

similartostandardhalogen,farlessthanfluorescentlamps.ThereasonLEDtechnologyissaidtobesoefficientisbecauseitdirectsmostofthelightinonedirectionsoitisgoodforsigns,stoplights,wayfinders,andotherdirectionallighting,butnotnecessarilyefficientforoverallroomillumination.

6.Typicallamplife

a. FluorescentT820,000hours,or3yearsat18hours/dayb. FluorescentHighOutputT520,000hours,or3yearsat18hours/dayc. MetalHalide20,000hours,or3yearsat18hours/dayd. IncandescentALamp750hours,or2monthsat18hours/day

e. IncandescentMR16Halogen10,000hours(withspeciallamp),or11/2years

at18hours/dayf. LED100,000hours,or+15yearsat18hours/day

7.Tohelpwithpreliminarysitebudgetcosts,beforeanengineermaybeinvolvedonaproject,thetypicalspacingofpolelightsinaparkinglotisapproximately100oncenterwithananticipatedinstalledcostfornondecorativepolesof$2,000each.Decorativepoleswilltypicallybeapproximately$3,000installed.

8.DuetotheadoptionoftheInternationalBuildingCodes,compliancewiththeInternationalEnergyConservationCodeisalsotypicallyrequired.Uponsubmissionofthe100%CDdrawingstothebuildingdepartment,itshouldbeanticipatedthatstampedcopiesofthecomplianceformsbesubmittedbytheelectricalandmechanicalengineers.

DownloadElectricalSystemsRulesofThumbprintablesheetforreference.

DownloadLightingSystemsRulesofThumbprintablesheetforreference.

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