Early Electrical Wiring Systems in American Buildings ...

Early Electrical Wiring Systems in American Buildings, 1890-1930 Author(s): LALUCE D. MITCHELL Reviewed work(s): Source: APT Bulletin, Vol. 42, No. 4 (2011), pp. 39-45 Published by: Association for Preservation Technology International (APT) Stable URL: . Accessed: 25/11/2012 17:00 Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at . . JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@. .

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Early

Electrical

Wiring

Systems

in

American

Buildings,

1890-1930

LALUCE D. MITCHELL

Vintageelectricalwiringsystems are likea mysteryinsideyour walls,maybedangerousbutoften forgottenT. his paper proposes thattheyare uniquearchitectural objectsworthyofstudyand even ofpreservationwhenpossible.

, . CL- .i S?

Fig1.. Tabloefthecommotnypeosfwire insulatioonnthemarkient1932andtheir applicatio"nNs.E.C.r"efertsotheNational ElectriCcaoldeF. romTerreClrl ofatndClifford C.Carred, .,AmericEanlectriciaHnasn' dbook, 3rded.(NewYorkM: cGraw-H19il3l,2)9,4.

Introduction

cal fire.B1y1900,howevera,n increas-

ApEiihnBsnnurliiemevdsnrihctmeiveeitosntnerprraeytidorieyteciTcfniohna.ilhwnfntsybatooiayrthsuiastfbnro,np-ietlmieilacdehnndoapheieggfsensnmarytrergoheprsollsdyIterido.temeie-geewsmostrlynoefwiianussetnnaestsesgltmiceaneamesodctf,omhitipiadnseirsopseatlicrtranichilott-nne-larewcidan-ifetictenrian.iltngugrywweisiohmnntxnaihroggtdrleusnyesietrnne,ciuloneitedgemfgrucslitehettnrbetcratetogpnertliishrrlecoonre,eriffiitdtficnciboTryitrretuwthtnc.oehyiieooamntonledcdmsotfctheihraAontp.stue2hmaeghsrnahtosebetafiaidraerrdneinishtdxceesB.aalewwideys'thscbtetb1otirui9enmrneie1gilgn5cdesas-,l

andelectricianms' anualsfromtheperiod,availabletothepublicina largely

TypesofInsulation

unknownbasemenatrchiveat theJohn CrerarLibraryat theUniversitoyf

Fromthebeginningc,opperwas used forelectricawl iresbecauseitwas

Chicago.Theperiodfrom1890 to 1930 was oneofconstantandentrepreneurial innovationintheelectricailndustry, includingthedevelopmenotfmany schemesofmerithatwereneverwidely adopted.Thus,manybrancheos fthe electricarlevolutionarenotmentioned

herebutcertainlwy arrantfurtherresearch.

Whenelectricitcyameintouse,itwas seenas heraldinagsolutiontoallthe problemosfgaslightinga,s itneither flickeredsm, elledn, orsmokedI.nexchangeh, owevere,lectricitdyidbring theveryrealriskoffirea,nddueto unreliabledistributioonfpowerandpoor wireinsulationinitsearlyyears,fires werecommoni,fnotoccasionallyexpectedA. constanpt ushwas madeto

knownto be thebestconductori;twas relativeliynexpensivaend availablein sufficienqutantitietso be usedbythe burgeoninigndustryE.arlyelectrical experimentwseredonewithbarecopperwiresininventoTrhomasAlva Edison'slaboratoryinMenloPark, NewJerseyin, 1879,butthesystem burnedoutbeforevenlightinugp the lightbulb.Thus,sometypeofinsulationaroundthewiresseemednecessary. Asidefromkeepingthestrengtohfthe electricaclurrenitntacti,nsulation helpedprotecthewiresfromdamage. Thereweremanyadditionadl emands placedon insulationh: eatandchemical resistancea,brasionresistanced,urabilitys,trengthan, dmalleabilityN.o materialavailableinthelatenineteenth

developbetterinsulationanddistributionpracticetshatwouldallowelectricityto bea consistentlsyafemethodof providinpgowerfortheneedsofdaily life.

centuryor firsdt ecadesofthetwentieth centuryhadall ofthosetraitss,o many differenptroductws eredevelopedfor differennteeds,costs,and situations (Figs.1 and2).3

Rubberinsulationwas perhapsthe

WiringSystems

mostcommonlyusedinsulationbecause

Electricitwyas,at firsta, toyforthe rich.One ofthefirsmt ento haveit installedinhishomewas bankerJ.P. Morganin 1882. IronicallyM, organ's personalibraryalso becameoneofthe firsitnteriortso burndueto an electri-

ofitswideacceptancebycodeofficials, itsrelativde urabilityit,ssuitabilittyo situationws heredampnesms ightbea problema,s wellas itssuperbflexibility. Howevere,venintheearlytwentieth centuryr,ubberwas knowntohavea

39

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40 APTBULLETINJ:OURNAOLFPRESERVATITOENCHNOLOG/Y42:4,2011

gradesofinsulationwitha higherrub-

bercontenwt eretypicallayvailable,for

highercost,whichwereabletohandle

slightlhyighertemperatureusp, to

140?F.Thehighesgtradewas 30 percent

rubberandwas requiredto beofthe

highesqtualityofrubber",para,"importedfromtheAmazonBasininBra-

zil.5Lower-qualitryubberinsulations

typicallwy eremadeofAfricanrubbers,

whichwereinferiobrutavailableat a

fiftohfthecost.6

Inorderto beusedina rubber-

Fig2. .Diagradmepictitnhgemultiplaleyers thamt adeupthethreperimatryypeosfwire insulatiaovnailabaltethetimoefitspublication in1923a:,rubbecroveredb;,weatherproof (triple-braicd,seldo)w; -burnTinhgel.attetrwo

insulatedwire,thecopperconductors hadto betocoatedwitha thinlayerof tininorderto helpthemresist hesulfur thatwas addedtotherubberduringthe vulcanizatiopnrocess.A7 sidefromrub-

aretypeosfclothinsulatioFnro. mArthLu.r CookI,nteriWoririnangdSystemfsorElectric LighatndPoweSrervic(eNewYorkJ:ohWn iley &Sons1, 923)2,54.

berandsulfuro,theringredienftsorthe vulcanizatiocnompoundvariedbut oftenincludedtalc,redorwhitelead, andlampblack.A8 thincoreofpure

shortlifespan- about25 years- and couldonlyhandletemperaturoefsup to 120?F.4Rubberalsohada tendenctyo degradewhenexposedtotheoilsthat wereoftenusedinotherelectricaclomponentsT. hefirsNt ationalElectrical Code,releasedin 1897,requiredthat rubberinsulationbeatleast20 percent rubberbycompositionT.hiswas consideredlow-gradeo,r "code"insulation, andwas nothighlyregardedT.wo

pararubberlaidinstripws asplaced overthebareconductowr ire,theentiretyofwhichwas thencoveredbya thicklayerofvulcanizedrubber.O9ne or twolayersofclothbraidsorinsulating tapeswereplacedon topofthevulcanizedrubberw, iththeoutermosrtequired to bea braid.1T0apesandbraidsfor rubberwireweretypicallmy adeof cottonandimpregnatewditha rubberizedwaterproofincogmpoundB. ythe 1920svulcanizedvegetabloeilswere beingmixedinwiththerubberinorder

toproducerubbersubstitutetsh, ereby

loweringthecostofrubberinsulation.

Howevert,hesesubstitutedsidnotad-

dressthephysicavl ulnerabilitioefsrub-

berinsulationto oil norimproviets

poormechanicasltrengthIn. the1930s

synthetricubberws eredevelopedt;hey

didnotdeteriorataes quicklyovertime

andweremoreresistantto oils.11

Lessexpensivtehanrubberbutmore

restricteidncode-alloweduseswas cloth

insulationT.hereweretwobasictypes

ofclothinsulationw: eatherprooafnd

slow-burnintgh; eycouldbe combined,

inwhichcasetheywerecalledslow-

burninwg eatherprooWf.eatherproof

insulationwas typicalluysedforexterior

wiringandhada roughsurfacea,s well

Fig3. .Diagrasmhowintghemultipcloeatings andjackettshamt akuepthemechanically protectoivuetecroatinogfcircullaoromF. rom anadvertisemfeonrttheAlphaduCcotmpany, as publishiendH.C.CushinSgt,andarWdiring forElectrLiicghatndPower2,3rded.(New YorkH:.C.CushinJgr, .1,917)3,32.

as a tendenctyogetstickywhenwarm, twocharacteristitchsatattracteldint anddust.Slow-burniningsulationwas oftenusedinareaswhererubbercould nothandlethehightemperatureitsh; ad a smooths,lickoutersurface.12

Fig4. .Drawinshgowintgypickalnob-and-tube installatipoenrr,equiremeonfths eNational ElectriCcaoldeF. romWilliaSm. Lowndes, HouseWirinangdBellWor(kScrantoPne,nn.: InternatiTonexatl boCoko.,1925)S,ec.5,p.56.

Theprimeoperationaaldvantageof cloth-insulatwedirewas itsabilityto handlehighertemperaturtehsanrubber insulationT.heclothsheathsconsisted ofmultiplleayersofcellulose-based fabricoryarns,uchas jute,hemp,or cottoni,mpregnatewditha waterproof orfireproocfompoundandthenbraided aroundtheconductorA. sclothbyitself absorbstoomuchwaterto beused safelyi,mpregnatincogmpoundws ere neededto reducethecellulosebase material'psorosityand at thesametime add resistancteo heatand shrinkage. Before1920 impregnatincogmpounds werecommonlyfossirl esinsandlinseed oil,whileasphaltandparaffiwn ax were morecommonlyusedlater.1T3helistof impregnatincogmpoundisncluded almostanythinwgater-resistamnto,stof themquitetoxic:asphalta, sbestosc, oal tar,mica,rubberl,inseedoil,wax,and othersT. o embedthecompoundinthe cloth,severallayersofthefabricwere dippedina troughofthecompoundand thenbakeduntildry.

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EARLYELECTRICAWLIRINGSYSTEMSINAMERICABNUILDINGS41

Fig5. .Drawinshgowintghevarietoyfsizesofbothsolidandspliptorce- Fig6. .Diagrasmhowinmgultipmleethodbsywhicahwirceouldbe lainknobtshawt ereavailablTeh. eporcelatiunbeatrighwtasusedwhen suspendeudpona solidknobusintgiewiresU. sintgiewirews assomewirepsassedthrougwhoodorcrosseidncloseproximFitryo.mCook2,27. thinogfanartperfectbeydearlwy iremeFnr.omCrofatndCarr6,58.

Similarinconceptbutoffering

Knoband Tube

slightlmy oreprotectiownasvarnished cambricinsulationa,lso referretdo as "varnishecdloth."Thisinsulationwas

madeup oflayersofcottonor muslin fabricwrappedina spiralandtreated witha nonhardeniningsulatinvgarnish, witha clothorasbestosbraidonthe outsideora leadsheathforuseindamp areas.Thistypeofinsulationwas considerablylessexpensivtehanrubbery,et offereadlargercarryincgapacityand didnotdeterioratine contactwithoils.14

Itschiefdisadvantagwe asthattheinsulationtendedtocrackwhenbentinto

smalleradiusesm, akingitimpractical foruseon smallerwires.15

Foreachofthetypesofinsulation describeadbove,theclothsheathwas braidedaroundtheconductorsF.or areaswheredampnesws as a concernor mechanicailnterferenwceas considered

likelya,second,moredurableouter sheathcalled"circularloom"(also called"flexiblteubing"orsimply "loom")wasrequiredbycodeto be placedoverthewires.Circularloom consistedofa seamlessw, oveninner tubewitha braidedcovera,llofwhich wastreatedwitha moisturea-ndflame-

proofcompound(Fig.3). Whileitwas notnail-proonfortrulymoisture-proof despitetheattempttso makeitso,circularloomwas thetoughesitnsulation availablebeforetheinventioonfar-

moredcable.Priorto 1900 loomwas usedwidelyfor"fishingw" iresthrough existinsgtructurews,hichwas often donewhenretrofittinnegwelectrical systemisnolderbuildings.16

In itsearlyyearselectricitwyas novel and consideredriskyand fireprone.For thesereasons,electricaslystemisnstalledinthe1880sand 1890stended

to be leftexposedbothas a status symboal nd foreasyaccessincase of malfunctionIn. existinghouseswires wererunup stairwellasndalongwalls, suspendedon woodencleatsorsecured ontothesurfaceofthewall bymetal clipsorstaples.1W7 hileexposedwiring was consideredobsoleteby1900 and was phasedoutinresidentiaalpplicationslongbeforethat,wiringsuspended on cleatscontinuedto be usedforlow-

costindustriailnstallationws ellintothe

twentietchentury.T1h8 eearliestcleats weremadeofwood,butinsystemisnstalledafterabout1900,thecleatswere generallymadeofporcelain.

Exposedwiringevolvedintoa standardizedandsomewhatsafersystem knownas knobandtube,whichcameto beusedprimariliynresidencesIn. dividualconductor(sreferretdohereas wires, butdifferentiatferdommodernwires, whichusuallycontainmultiplceonductorswithina singlewrappingw) ererun on thesurfaceosfwallsor,moreoften, concealedfromviewalongthesurfaces ofrafterasndwood studs.Knobswere

attachedto theraftebreamsor studsby a nailorscrewthroughtheircenterasnd wereprotectefdromsplittindgueto the insertioonfa pieceofscrapleatherbetweenthenailorscrewheadandthetop oftheknob.1I9nitiallysolidknobsmade ofporcelainoroccasionallyglasswere used.2W 0 iresweresuspendedbetween

knobs,andthenseparatetiewireswere

knottedaroundthewiresat eachknob

inorderto providesupport(Fig.4). Howevert,hesetiedconnectiontsended tocomeloosewhenusedwithsmall wires,so splitknobswererequiredfor usewithno. 8 wireandsmallersizes. Splitknobsweremadeofporcelainand consistedofa baseontowhichthewire slidanda cap thatclosedoverit(Figs.5 and6). Alongwithbeingsafers,plit knobssavedsignificantolnylabor.For installinagknob-and-tubsye stemt,he NationalElectricaCl oderequiredthe wiresto be suspendedatleast1 inch abovesurfaceasndto beatleast5 inchesapart.In additiont,hecoderecommendedthattwowiresnotbe laidon thesamesideofa raftearndrequired thatiftheywentthroughrafterosrwalls orcrossedeachotherincloseproximity, a porcelaintubewasto beused.2P1orcelaintubesweremadeinlengthrsanging from6 to 18 incheswithan internal diametefrrom5/sto 1 inch.2W2 henit was notpossibletosupporta wireon a knoborwhenwireshadto beplaced closerthantherequiredseparation and/orwithin3 inchesofan outletor switchw, ireswereto beenclosedin circularloom,describedabove.

Opinionson thesafetyofknoband tubevaried.GeorgeJ.Kirchgasser, authorofan earlyelectricaml anual, wrotein1914 thatwhilemetalconduit was "ofcourse"consideretdhebest option(as notedbelow),"therehasbeen nothingradicallyweakprovenagainst theknobandtubesystemas installedat present."2Y3ettherewas a movement afootas earlyas 1907togetknoband tubedisallowedbytheNationalElectri-

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42 APTBULLETINJ:OURNAOLFPRESERVATITOENCHNOLOG/Y42:4,2011

Fig7. .Drawinshgowinagporcelacionver designetdobeusedwhentwosectionosf woodmoldincrgosseedachotherin,ordetrhat thewirews ithtinhemdidnotgetplacedintoo closeproximtiotoythewr iresF.romLowndes, Sec.5,p.58.

cal Code,anditwaswidelyderidedas beingsusceptiblteo beingchewedby rodentasndbeingcoveredbysawdust andothermateriatlhatsifteddown withinwalls.2T4heelectricaclodecontinuedto approveitsinstallationh,oweverb, ecauseitwas believedthatthis lowest-cosotfsystemws astheonlyway manysmalltownswouldbe ableto get electricaslervicea,ndeliminatinigt wouldkeepthepowerstationfs rom gainingtheirbusiness.25

WoodenMolding Whileexposedsystemws erenecessary fortheearlydayswhenelectricitwyas an uncertaianndtemperamentnaelw inventions,oonsuchsystembsecame regardedas unsightlyO.ne attemptto concealthemwithstylewas toenclose thewiresinspecialwoodenmolding. To thecasualobservert,hesemoldings lookeddecorativea,ndsupplierpsromotedtheirinclusionas partofthe decorativsechemeofthehome,though theirlocationhad to followthepathof electricaclircuittshroughthehouse. Supplieresncouragedthepurchaseof extrasectionsinorderto keepthedecorativeschemeconsistent.M26oldings consistedoftwopiecesofwood. One piece,thebase,was attachedtothewall withscrewsandhadtwoorthree groovesinwhichindividuawl ireswere to belaid. cap was nailedto itand couldbe removedforservicingC.aps wereavailablewithvariousdecorative

effecat continuouvsersionoftheolder

exposedwooden-cleastystemsa,s the

wireswerelaiddirectlaygainstthe

wood,creatinga firehazard,especially

whenwatergotintothewallandthe

wood.Wiringguidebookgs enerally

encouragedcoatingwoodenmolding

withshellacorpainttodiscouragwe ater

infiltratioWn.hilemoldingwas sup-

posedto bemadeofhardwoodst,he

mostcommonlyusedandlessexpensive

typesweremadeofsoftwoodsw, hich

didnotresistwaterwell.28Finallyd,is-

Fig8. .Drawinshgowinagfittidnegsignefdor woodmoldinsygstemtshaatlloweadreceptacletobeplacedintherunofthecircuiBte. fore 1915manryeceptaclaecsceptepdlugws ith

guisingwiringas a decorativme olding railencourageditsuseas a nailingstrip byownerswhodidnotknowitsprimarypurposeT. hedrawbackosfthis

EdisosncrewendsF. romGeorgJe.Kirch-

systemwerewellnoted,and by1910 the

gasserE,lectrLicighatndMotoWr irin(Mgilwau- NationalElectricaClodelimitedthe

kee:ElectrofoPrucbelishiCnog.,1913)4,8.

areasofa buildingwherewooden-

profiless,o as tocreatethelookofa picturerail.Sectionsofmoldingranged

moldingsystemcsouldbe usedinsignificantamountsandrequiredthatonly rubber-insulatwedirebe usedwithit.29

fromIV2to 6 incheswideandwere3/4 inchdeep.Typicallyw,ireswereheldin thegroovesbytemporarbyradsduring installationb,uttherewerepatented systemws ithspeciallyshapedgrooves to betterholdthewires.2W7 herecir-

Nonetheless,uchsystemrsemained legalandwerephasedoutgraduallyand voluntarilbyybuildersD. uringthe 1920swoodenmoldingbeganto be referretdoas "woodenraceway."

cuitsofwiresconcealedinwooden moldingcsrossedeachothers,pecial porcelaincross-ovejrointswereemployed(Fig.7). In additiont,herewas a fulllineofporcelainfittingtshatfitonto woodenmoldingisnorderto allowinclusionofa receptacloerswitchinthe run(Fig.8). Inthebasemenotfthe 1887 GlessnerHouseinChicago,sectionsofwood moldingstillremainwith wiringpresenitnthegrooves(Fig.9).

Thewooden-moldinwgiringsystem hadseverapl racticadl isadvantages. Whileknobandtuberequiredwiresto besuspendedbyatleastan inchbeyond anysurfacew, oodenmoldingwas in

MetalMolding

Metalmoldingwas a productquite similarinconceptto thewood molding describedabove,witha baseanda cap thatcouldbe removedbyslidingitoff. Whileitappearsto havebeenavailable before1910,metalmoldingdidnot becomesuccessfuclommercialluyntil afterWorldWarI, whenitbecame widelyused.30

TheNationalElectricaCl ode allowed theuseoftwobrandsofmetalmolding: National,byNationalMetalMolding Co. ofPittsburgahn,dLutz,byAmericanCircularLoomCo. ofBoston.31

Fig9. .Anexampolefextanwtoodmoldining Fig1. 0.Drawinilglustratsiencgtionparl ofiloefs

thebasemenotftheGlessneHrouseMuseum, twocommonly-tuysepdeosfmetaml olding.

ChicagIol,linoPish. otograbpyhtheauthor,

FromLowndeSse,c.5,p.59.

courtesoyfGlessneHrouseMuseum.

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EARLYELECTRICAWLIRINGSYSTEMSINAMERICABNUILDINGS43

Fig1.1. Drawinshgowintgypicianlstallatoiofn enamelerdigicdonduicto,mmonrleyferrteod as "blacpkipe.F" romLowndeSse,c.6,p.4.

SectionosfNationalmoldingweremade ofsheetmetalandwererectangulairn crosssectionw, ithroundedcorners. Theycameinlengthosf8 feet4, inches. Typicadl imensionfsorNationalwere about1 inchwidebyslightloyvera xh minacnhduefeapc.tAusrmewdah,lliecrhvwerassiaobnwouats5aIslsionch wideand3/8inchdeep.32Sectionsof Lutzmoldingweregalvanizedsheetmetalchannelsi,ntowhicha flatstripof sheetmetalwastuckeds,ervingas the cap.Itcamein10-footlengthsA. third systemknownas Wiremoldp,roduced bytheAmericanConduitManufacturingCo. ofPittsburgwh,as metalmoldinginwhichthebaseandthecap were crimpedtogetheirnthefactoryf,orming a rigidconduitrequirinwg iresbepulled throughit.Italso camein 10-foot lengthsF.igure10 showsthesectional differenbcetweentheNationaland Wiremolsdystems.

Eachofthesethreecompanieps rovideda setoffittingsus itedforevery possiblesituationb,utthefittings workedonlyon thatsystemr,equiring buildertso useonlythatcompany's productfsora wiringjob.33Fittingws ere producedfortransitioninfgrommetal racewaytorigidconduitM. etalmolding

was installedusingflat-heasdcrews affixetdo thewallthroughcountersunk holesplacedevery2 feetinthebaseof themoldingF. orpropertoywnersm, etal moldingwas popularbecauseitreduced laborcostsby20 to 30 percenotver rigidconduit.3D4uringthe1920smetal moldingbecamereferretdoas "metal surfacreaceway,a"ndmodifievdersions continuteo beusedinnewbuildings today.

RigidConduit

Fromat least1900,itwas knownthat metalconduitwas thebestchoiceto protectwiresfromimpactandwater andwas regardedas thebestsolution fora reliableelectricailnstallation(Fig. II).35 Howevert,henas now,metal conduitwas expensiveA. conduitinstallationcostabouttwoand one-half timesmorethantheequivalentknoband-tubeinstallation.T36he earliest electricaclonduitsweremadeofvegetablefiberimpregnatewditha resinous compoundor ofbrass,butneither proveddurable.3U7ltimatelyth, eshape, thicknesst,hreadinga,ndcommon lengthofconduit(10 feet)werederived directlyfromgas pipingusedpreviouslyI.n fact,gaspipingwas often reusedwhenretrofittienlgectricitiynto olderbuildingsL.ikegas pipe,conduit was soldintradesizesrangingfromV2 inchto 6 inchesb, uttheinteriodriameterofthepipewas actuallyslightly largerthanthisdimensiona, practice thatcontinuetsoday.3C8onduitspecificallymadefortheelectricailndustry was requiredbytheNationalElectrical Code to be reamedinsideto freeitof burrsandwas typicallymadeofsofter steelthatwas easierto bendthancommercial-gradpeipe.39Thoughround conduitwas themostcommontype, ovalconduitwas also made.Theadvantageofovalconduitwas thatitsprofile was sufficienttlhyinso thatitcouldbe laidon thesurfaceofa plasterwalland a customarycoatingofplasterwould obscureitfromview.40

Twotypesofconduitexistedl:ined andunlinedL. inedconduithada layer ofinsulatinfgiberinsidetheouteredges oftheconduitm, ostoftena tubeof papertreatedwithan asphalticompound.Linedconduithad beenpopular becausebeforeabout1905 wireswere

availableonlywitha singlebraidof outercoveringt;helayerofconduitliningwas intendedtoprovidea secondary levelofprotectionH.oweverb, y1910 unlinedconduitwas becomingmore popularbecausethenewdouble-braided wirecouldbe usedwithinit.41There werethreegradesofconduitconstruction,andeachgradecamewithorwithoutscrewedends.4T2heleastexpensive typec, losedjoint,consistedofa sheetof metalthathadbeenbentintoa tube, butthetubewas leftopen,resultinigna C-shapedcrosssectionandan open seam.Whenthepipeendswerethreaded to bescrewedtogethetroadjacent lengthst,heseamsalongthepipelength werewelded,consideretdheleastreliablejoiningmethodA. secondtype, brazedconduitw, as alsomadefroma bentmetalsheet,butinall variationtshe seamsweremechanicalljyoinedto createa circulartube.Thethirdand mostexpensivteypewas solid-drawn seamlessconduits,imilarto thetype commonlyinusetodayC. onduitcoatingsalsovariedL. ower-gradceonduits wouldbe eithergalvanizedorenameled, buthigher-qualiptyroductws ouldhave bothfinisheasppliedto boththeinterior andexteriorW. hileenamelsvariedin qualityas well,theyweregenerally blackincolor,leadingto thetypical contemporarnyamegiventoearlyconduit:"blackpipe."

Sincemostearlyelectricaslystems, includintghoserunnintghroughconduit,didnothavea groundwire,itwas assumedthatintheeventthatthewire insulationfailedt,heconductorws ould findtheirgroundinthemetalsheath thatsurroundetdhemR. atherthan ignorethispotentiaslituationm, anufacturersoldseverasl ystemosffittings intendedto linklengthosfunscrewed conduittogethetroproducea continu-

Fig1. 2.Drawinshgowinagnexampolefoneof severalvailabslye stemfsorensurinthgeouter sheatohfrigicdondupitroduceadcontinuous grounTdh. epinastconnecttoeachoftwo adjacenctondusietctionFs.romS. C.Batstone, ElectrLicight-Fit(tLionngdoWn:hittak&eCro., 1914)3,6.

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44 APTBULLETINJ:OURNAOLFPRESERVATITOENCHNOLOG/Y42:4,2011

flexiblceonduitB. ecausetherewasnota Acknowledgements

Fig1. 3.Diagrasmhowintghecoveringgivento a)standarBdXandb)lead-sheathBeXdL versionofsarmorceadbleF. romCook2,27.

needforthepullingofwiresthroughit, therequired iameteorfarmoredcable couldbe smallerthantheequivalent flexiblceonduit.4I8tsheavy-dutcyonstructioanlso alloweditto becomethe de factoreplacemenftorcircularloom forinsertinwgiresinexistingstructures.

Conclusion Whatis thevalueinthisinformation forpreservatiopnrofessionalsD?uring fieldinvestigationfsi,ndinagn antique wiringsystemcan assistin datinga buildingb,utitcanalso helptelleven

I amgrateftuotlhestafofftheJohCnrerar LibrarayttheUniversoiftCyhicagfoormaking sucha valuabalerchivofeelectrihcailstory availabtleothepubliAc.lsoI,wouldliketo thanPkrofessAonrnSeullivaTnh. ispapesrtarted asa reporant dpresentatfioorhnerclasson HistoricMalateriaalnsdTechnologainesdh, er belieifnitsvaluencouragmedetodeveloipt firsatsa presentataitotnheAPTannuaclonferelinkceteiont2h0a1n0BaknildTlfyinraedl,ailrystehctiopsofartpheeGrI w.leosusnlder HouseMuseumas,welalsmyfelloswtudenitns thegraduaptreograimnhistorpirceservataiton theSchooolftheArItnstituotfCe hicagfoo, r theierncouragemaleonntgtheway. Notes

ousconductinsgurfacteoguidethe wcuartreerpnittpoet(hFeing.e1a2r)e.4s3tgInroournddeur,tsoucallalmya p

moreofthebuilding'sstoryT. heinvestmentmadeina wiringsystemmakesa statemenats towhatresourcetshein-

1.JilJl onneEsm, piroesfLightE:diso,nTesla, Westinghoaunsdet,heRacetoElectritfhye Worl(dNewYorkR: andomHouse2,004),5, 9.

anyofthefittingtos theconduitt,he conduithadto be cleanedofitsenamel

dividualorcommunittyhatconstructed thebuildinghad availableto themat

2.TerreCllroftW, irinogfFinisheBduildings (NewYorkM: cGraw-H1il9l,15)2, .Littlies

coatingattheconnectiolnocation.

thetimeandas tothepresumedperma-

nenceofthestructurEe.achinstallation

FlexibleConduitand ArmoredCable

also representasmomenitnthehistory

Tanhdeafvirasilftalbelxeaibrloceuonndd1u8i9tw5.a4s4dBeyvtehleoped 1920sitwasreferretdoas Greenfield, thenameofa prominenmt anufacturer, justas itistoday.4F5lexibleconduit consistedofinterlockincgonvexand concavestripsofgalvanizedsteel woundspirallyuponeachotherw, hich produceda smoothsurfaceon boththe interioarndtheexteriorIt. was essen-

tiallyconduitthatcouldbendinany directiontofacilitatme oreflexible

installationb,utbecauseofgapscreated inthemetalsheathwhenitwas bent,it was notcompletelwy aterproofV.ersionsmadeofbothoneandtwolayers ofmetalstripws ereavailable.Though thesingle-strvipersionwas morecommonlyused,twolayersofmetalimprovedthemoisturreesistance.M46ore expensivtehanrigidconduitf, lexible conduitwas usedonlyinplaceswhere rigidconduitcouldnotbe conveniently used.47

Armorecdablewas identicatlo flexi-

oftheyoungbutquicklyevolvingelectric-lightiinngdustryW. ithineachofthe wiringsystemdsescribeda,n armyof entrepreneucrosmpetedto providethe mostusefuls,afe,or distinctivfeittings. Sinceelectricaslystemasreupgradedfar moreoftenthanthebuildingtsheyare partof,itis likelythatwhena fittinogr sectionofmoldingfromthelatenineteenthor earlytwentietchenturyis foundi,tis oneofthefewremaining examplesofitstypeandthusworthyof preservation.H4o9wevert,hepreservationofvintageelectricaslystemfsacesa challengethatbuildingtshemselvedso not:theever-expandinlogad requirementsofmoderntechnologicaslociety and,mostimportantlays,lewofconcernsabouttheirsafeoperationm, ost ofthemquitevalid.Thus,vintageelectricalsystemasreobsoleteand sometimesdangerousb,uttheystillrepresent a fascinatinhgistoricasltorythatis beggingto betoldandis indangerof beingforgotten.

bleconduitinmostrespectse,xceptthat thewireswerepre-drawdnuringmanufactur(eFig.13). Introduceidn1901

LALUCED. MITCHELLreceivehdismaster's inhistorpicreservatfiornomtheSchooolfthe ArtInstituotfeChicagion2011.Hewasan APTStudenStcholaartthe2010Denver

andcommonlryeferretdoas BX (aftera popularbrand)fromat leastthe1910s, itcameina standardversionandone witha leadsheathjustinsidetheouter

Conferenwceh,erheepresentoendthitsopic. Heisa preservatsipoencialiasttFlynn BattaglAiarchiteicntBsuffalNo,ewYorkH. e canbereacheadtlalucedm@.

coatingw, hichwascalledBXL.Ar-

moredcableoffereaddvantageosver

knowanboutCrofetxceptthaht elivedin UniversCitiytyM, issourdiu, rintghe1910sand emarolsylt1e9a2d0esirbn, udtihsesaepmpienaarttsooifbopnereantchtiefcioanrl-eformatioonnelectricwailrinignthiesrawhen a wholgeeneratioofnnewwireme(ansthey wercealledthenn)eedetdobeeducateidnthe trade.

3.MaximiliFanerraondMelissLa.Cook, ElectrWic irinagndLightiningHistorAicmericanBuildin(gNsewBedforMd,ass.A: FC/A NorteCkompan1y9,84)7, .Thisisoneofthe onlymoderbnooktshatalkisn-depatbhout earlywirinsgystemSse.ealsoGordoBnock, J"Eovuarlnu(aaJltainEnl.g/ecFt1erb9i8.cW9a)li2:r6i-n3g3O,."ldHouse 4.TerreCllrofatndCliffoCrd.Carre,d., AmericEanlectriciaHnasn' dboo,k3rded. (NewYorkM: cGraw-H1il9l,32)6, 84. 5.AmericSatnee&l WirCe ompanCya,talogue andHandboookfElectricWalireasndCables (ChicagAo:mericSatnee&l WirCe o.,1910), 141.

6.Africarnubbewrasapparentinlyferior becausoefa parasitinethesapofthetreetshat destroytehdepropertoieftsherubbeBrr. azilian griturwebawbisnkewtrilhalseenabdroyetasamfF. froeokcmgtSebieyvyddtennhofeepFyfba.Wyraaasnlikutbeetterhc,aautse ElectrWic irinagndFittinfgorPlumbearnsd Gasfitt(eLrosndonS:cottG, reenwo&odSon, 1908)3, 5. 7. Walke3r4, . 8.FerraondCook8, . 9.Theinclusioonfthepurepara("white") rubbecroreatthecenteorfwiresseemtsohave mbeeennbtoasfsteedmchonrobelyotTgrhyade.fiitritosrhtnuabnrbeeiqrnusiurlea-tion waspurerubbeornlya,ndthatlayewr askept evenaftetrhesuperiovrulcanizleadyewr as typicalaldydedarounidt.AmericSatnee&l W nrueicbrebCesesora.,-rpTiy.nh1.se1tu9rwl,aaaditrreigestdueioectsncthioaaonlitlnsasdytiresutrcocubtsoeisfoueiannndS-.

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EARLYELECTRICAWLIRINGSYSTEMSINAMERICABNUILDINGS45

C.BatstonEel,ectrLicight-Fitt(Linogndon: Whittak&erCo.,1914)1, 8. 10.Walke3r6,. 11.FerraondCook9, . 12.CrofatndCarr5,88.

28.IbidS. oftwoovdersionwseremadeof Americwanhitwe oodandanevenlessdurable versiownasmadefromyellowdeal. 29.H.C.CushinSgt,andarWd irinfgorElectriLcighatndPowe,r23rded.(NewYorkH: . C.CushinJgr, .1,917),127.

13.FerraondCook7, .

30.FerraondCook9, .

14.AmericSatnee&l WirCe o.,163.

31.Kirchgass5e2r.,

15.TerreCllroftW, irinfgorLighatndPower (NewYorkM: cGraw-H1il9l2, 4)1, 32. 16.FerraondCook1, 4.

32.CrofatndCarr6,96. 33.ArthuLr.NelsonIn, terioErlectrW ic iring (ChicagoA:mericTanechnicSaolciety19,20),

17.F.C.AllsopP,racticEalectric-LiFgihtting 30.

(LondonW: hittak&erCo.,1892),138;this bookisavailabloenGooglBeooksA. ttaching wiretsowallswithstaplews asknowtnobe

34.CroftW, irinogfFinisheBduildin,g1s30. 35.Kirchgass7e0r.,

badpractiecveenbythetimtehisbookwas

36.ArthuLr.CookI,nterioWririnagndSys-

published.

temfsorElectrLicighatndPoweSrervic(Ne ew

18.FerraondCook,11. 19.CroftW, irinfgorLighatndPowe,r35.

YorkJ: ohW n iley& Sons1, 923)2, 44.Atable from1923listtshefollowinreglativcoestfs or aninstallatiroing:icdonduicto,nceale1d0: 0;

20.CrofatndCarr7,01. 21.Ibid.

rigicdonduietx, posed1:25;armorecdable, newwork6:5;knob-and-twubirein4g0: ;open [exposedw]irin5g0: .

22.Batston5e6,.

37.FerraondCook,15.So-calle"dbrass-

23.GeorgJe.KirchgassEelrec, trLicighatnd MotoW r irin(Mg ilwaukeEel:ectrofoPrucbelishinCgo.,1913)7, 0.

armorecdonduitd"idnotbecomwe ideluysed intheUniteSdtatesIt.did,howevebre,come commonulsyedincontinenEtualrope.

24.FerraondCook1, 4. 25.Ibid.1, 5. 26.CroftW, irinogfFinisheBduildin,g1s34. 27.CrofatndCarr6,85.

38.WilliamS.LowndeHs,ouseWirinagnd BellWor(kScrantoPne,nnI.:nternational TextbooCko.,1925)S, ec.6,p.2. 39.Cook2, 11. 40.CrofatndCarr7,00.

41.JosepGh.BranchE,lectrW ic iring (ChicagoB:rancPhublishiCnog.,1910),105.

42.Batston3e3,. 43.Ibid.3, 6. 44.Theexactdateisunknowbnu,tonpage 272ofhisbookE, nglishmWan.PerreMnaycockstatetshathearmorecdablesystewmas broughfrtomAmerifcaouorrfivye earbsefore thebook'dsateofpublicati(o1n899)S. ince Ameriacna dEnglanadppeatrohavedeveloped relativeplayrallelectricinaldustriaersm, ored cablewaslikeldyevelopendotlongbefore 1895.SeeW.PerreMnaycockEl,ectrWic iring, FittingSsw,itchaensdLamp(sLondonW: hittake&r cCo.,1899). 45.LowndeSse,c.6,p.15. 46.Cook2, 26. 47.CroftW, irinfgorLighatndPowe,r110. 48.Branch1,07. 49.Foranexamploefanelectricsaylstetmhat waspreserviendplaceforhistoricvaallues,ee ElisabetWh.Doerman"nR,estoratioofn ElectricSayl steminstheJameJs.HillHouse," BulletionftheAssociatifoonrPreservation Technolo1g8y,no.3 (1986)5: 6-64.

I TAhsseAoPciTBatuoilfoPlnertieisspneurbvlaiTstehiboceyhntdnhoelttmBiNehuceebTlhmluEeniRtbableiitneqNnnenruootdnvfAejgreecircTsgryfaIeeaoniFoa|isepontnnostNpsalferimm.ilzrArAoniaayncterosdcteLahnuraiceitotceebtne0diina.sosaftfiotrsccnononhapearirnnatpeaimlpesdtorw,tattdetiaorhnriitvtotspedhcuieinsoriicespsianaaletocenlcr,feis-edpslinary

.

yg;

EVERGREENE Architectural

Arts

Conservation and Finishes Restoration T:212.244.2800F:212.244.6204

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