ENTRANCES, HOLES, AND RISERS CEF CONDUIT

Transcription

1 BELL SYSTEM PRACTCES AT&TCo Stadard SECTON ssue 1, February 1978 CEF CONDUT ENTRANCES, HOLES, AND RSERS CONTENTS PAGE 2. CONDUT ENTRANCES GENERAL CONDUT ENTRANCES... CEFACCESSHOLES CABLE HOLES RSER ENTRANCES REFERENCES.. CEF CONDUT, RSER, AND PULLNG HARDWARE f AND HOLE STANDARDS Coduit etraces to cetral office buildigs fall ito two categories: floor etraces ad wall etraces. The size ad locatio of these {Jpekgs deped upo the CEF desig, the size of the buildig (sigle or multistoried), ad the eeds of the cetral office. 2.o2 Floor etraces for vertically-racked, above-surface CEF desigs ca be costructed by either peetratig the floor with the duct itself or usig duct coupligs. both methods, the ducts will exted approximately 3-1/2 iches above the fiished floor level. The umber of ducts ad the spacig betwee the ducts (l-foot miimum) will vary with cetral office requiremets. (See Fig. 1.) This sectio discusses ad provides stadards for CEF coduit etraces, risers, ad holes. These stadards are provided for use i the desig of ew buildigs or buildig additios that are iteded to house telephoe equipmet that meets the requiremets of Sectio , New Equipmet-Buildig System (NEBS), Geeral Equipmet Requiremets. 1.2 This sectio supersedes Sectio 6.2 of Specificatio X-743, NEBS Buildig Egieerig Stadards (BES). Wheever this sectio is reissued, the reaso for reissue will be listed i this paragraph. 1.3 The Cable Etrace Facility (CEF) iterfaces with the outside plat cable ad the mai distributig frame equipmet. From a structural stadpoit, this iterface is made at the walls of the CEF ad ivolves coduit etraces, cable riser opeigs, ad cable holes. This sectio provides a descriptio of these iterfaces for above-surface, subsurface, ad duplex CEF systems. Space requiremets, locatios i the CEF, ad typical istallatio optios are preseted. 2.3 All coduit etraces, those empty ad those cotaiig cable, must be plugged with stadard rubber duct plugs. These plugs seal the eds of the ducts ad prevet potetially hazardous gases ad liquids that may be preset i the coduit structures from eterig the buildig. Waterplug ad B Duct Sealer ca also be used to plug coduit eds. 2.4 To provide additioal protectio agaist hazardous gas igress ito a CEF, gas vetig chambers shall be employed as part of the coduit system close to the buildig foudatio. A typical chamber cosists of a small udergroud structure of reiforced cocrete costructed to accommodate the required duct capacity as show i Fig. 2. Gas vetig chambers for various duct capacities should be desiged to meet the imposed soil load requiremets at the istallatio site. 2.5 Plastic duct termiators or ducts directly embedded i cocrete ca be used M both eds of the gas vetig chamber. The umber of ducts or termiators ad their arragemet i the walls deped upo the size ad shape of the coduit structure eterig the buildig. Wall areas cotaiig duct termiators are usually recessed to provide a keyway should cocrete ecasemet be required. America Telephoe ad Telegraph Compay, 1978 Prited i U.S.A. Page 1

2 SECTON [ 1 1 SDE VEW Fig. 1 Above-Surface CEF Duct Etrace 2.6 The gas vetig chamber fuctios as a vetilatio chamber through which the plastic ducts pass. Each duct must cotai a series of vet holes or otches i its wall sectio to permit ay gas to escape ito the chamber. Two 4-ich diameter vet pipes extedig either alog the outside buildig wall or iside the wall are required to achieve maximum atural vetilatio for heavy ad lighter-tha-air gases. The vet-pipe opeig must ot be located i the viciity of ay widows or other vetilatio opeigs. 2.7 Wall-type cable etraces, usually associated with subsurface CEF desigs, ca be costructed usig stop-type duct termiators or ducts eclosed by the wall itself. Termiators should be used with plastic coduit, because cocrete adheres to plastic poorly. The umber ad spacig of ducts will deped o the CEF desig ad cetral office eeds. Duct plugs are required i both empty ad occupied ducts. Termiators have provisios for termiatig ducts as well as accommodatig duct plugs for sealig. 2.8 Gas vetig chambers for wall-type etraces ca be costructed itegrally with the wall of a subsurface CEF. (See Fig. 3 for a typical istallatio.) large buildigs requirig may ducts, the type of istallatio show i Fig. 3 should be employed. This optio permits a uiform wall thickess at the cable etry locatio ad does ot compromise the structural itegrity of the buildig. 3. CE; ACCESS HOLES AND PULLNG HARDWARE 3.o1 Each basic CEF alley should be equipped with a access hole or cable chute located above the duct etrace or at the ed of the alley opposite the duct system etrace. The access hole should be cetered i the alley. The exterior appearace of the access hole should be located so either a reel trailer or a lie truck ca be positioed coveietly. The access hole should have a secure cover. 3.2 Pullig iros should be located i the floor ad ceilig at both eds of the CEF alley, as well as at each ed wall. f the vault arragemet ivolves beds, pullig bars should be located at each bed to permit chagig the pull directio. Page 2

3 1SS 1, SECTON FROM TOP OF CHAMBER.,*, -FROM OF BOTTOM CHAMBER which stub cables reach the mai distributig frame or protector frame. They are located i the cetral areas of buildig bays away from the colum lies. all cases, discrete holes below each frame vertical, sized to satisfy stub-cable desity requiremets, should be provided. formig the holes, eough cocrete is elimiated so that the icrease i floor slab flexibility must be cosidered i the desig. 4.2 There are three cases to cosider i the desig of floor opeigs betwee the CEF ad the distributig frame area: (a) (b) (c) The modular Protector Frame (PF) The Double-Sided Protector Frame (DSPF) The Low-Profile Covetioal Distributig Frame (LPCDF). vetdthol$s N,$ f/ndut 4 DA C PLASTC Fig. 2 Gas Vetig Chamber (Trap) for Office With Above-Surface CEF 3.o3 a above-surface CEF, irowork above the duct etraces ad a access hole must be provided. The access hole ca be located i either ed wall of the CEF, depedig o the locatio of the cetral office mahole ad the coduit etrace cofiguratio. rowork to support sheaves ad other cable placig apparatus must be provided. A miimum load-bearig capability of 2 pouds is recommeded. 3.4 Access holes, all pullig hardware, ad irowork should be reviewed by Outside Plat Egieerig. The proposed desig should be coordiated with costructio forces to resolve ay cable-pullig difficulties ad with the buildig desigers to assure the adequacy of the buildig support steel. 4. CABLE HOLES 4.1 Cable holes or slots i the ceilig of a subsurface CEF provide opeigs through 4.3 the past, cable holes uder the frames were costructed with cotiuous slots, iterrupted slots, or small holes. The supposed advatage of slots is that they provide a large area for cable. However, they are difficult to seal for fire protectio ad expesive to build. Small holes with a oe-to-oe correspodece to the frame verticals provide sufficiet area for the cables. They eed ot jeopardize the structural itegrity of the floors, costitute the least expesive method, ad ca be sealed easily before or after cable istallatio. 4.o4 Small idividual holes are recommeded for opeigs to frames. A stadard logitudial patter of holes caot satisfy all buildig desigs, sice frame dimesios differ ad frame lieups vary. However, stadardizatio of aisle width ad buildig height should make it possible to select a suitable hole patter for ay oe particular frame. 4.o5 A series of small holes ca meet all cablig, structural, ad fire-protectio requiremets. For the DSPF ad LPCDF, 6- by 4-ich holes should be formed ito the slab 8 iches o ceter as show i Fig. 4. This size is adequate for the cable requiremets ad allows extra space for budles of cable that pass through the hole obliquely. Whe a perforated block is used, 1- by 4-ich holes should be formed to hold the perforated block. The more closely spaced holes for the modular PF should be 6 by 2 iches as show i Fig. 4. Agai the hole area is sufficiet for the Page 3

4 SECTON ~ BOTTOM OF chamber [ \,TOP vew OF Termiator [ h OPTONAL CEF WALL CONFGURATON,VENT HOLES N CONDUT Fig. 3 Gas Vetig Chamber (Trap) for Office With Subsurface CEF cable volume ad the smaller size is structurally more desirable for the closely spaced holes. 4.6 t is importat that floor desig, with the proposed frame opeig patters, be cosistet with the structural requiremets of New Equipmet-Buildig System (NEBS). Of sigificace are the 15-psf desig live load ad the 12-foot 6-ich ceilig height from the slab to the bottom of the lowest projectio. The floor i the mai frame area must carry the same live loads as the remaider of the buildig. The floor structure should also be o deeper tha the floor structure o the same level i the remaider of the buildig. Figure 5 shows schematically how this framig might be doe for differet methods of costructio ad types of equipmet frames. 5. RSER ENTRANCES 5.1 the duplex CEF system, riser cable spaces will be required to route icomig cable from the CEF to frames located o the upper floors. The riser spaces may simply cosist of holes i the floor betwee colums alog a exterior wall, idividual coduit, or a lie of holes i the floor behid a partitio i the buildig. Shafts are ot recommeded sice they are oly slightly more ecoomical to costrtit tha sleeves ad the required fire ad smoke stoppig is at best difficult ad costly. (See Sectios ad for fire-protectio requiremets at floor opeigs.) 5.2 Riser space for cables is most ecoomically provided, from a structural stadpoit, whe a series of discrete holes i the floor slab is used. The geometry of the wall-mouted splice closures ad the diameter of the cable require 4-ich iside diameter steel sleeves or coduit cast ito the cocrete o (miimum) l-foot ceters. Because the holes are relatively small, the reiforcig steel i the cocrete floor ca be diverted aroud them easily without iterruptig ay of the bars. However, i formig the holes, eough of the cocrete sectio is elimiated that the icrease i floor slab flexibility must be cosidered i the structural aalysis. s.3 From the viewpoit of utility, structural itegrity, ad fire safety, the sleeves are best laid out i, or adjacet to, the colum lie alog a exterior wall of the buildig directly above the CEF. This locatio distributes the sleeves alog the legth of the CEF as well as the PF. Page 4

5 1SS 1, SECTON dividual metal coduits ca also be used to carry riser cable betwee floors. With respect to fire protectio, i desigs without partitios or coduit, idividual sleeves ad slots should be sealed both before ad after cables uass through them. Sectios --km,, ad co~er requiremets U c1 DOUBLE SDED PROTECTOR FRAME (DSPF) a LOW PROFLE CONVENl lonal DSTRBUTNG FRAME (LPCOF) m o MODULAR PROTECTOR FRAME (PF) * THS DMENSON SHOULD BE 1 WHEN THE RECTANGULAR OPENNG S OCCUPED BY A PERFORATED BLOCK CONTANNG HOLES SZED TO ALLOW THE PASSAGE OF ONLY ONE CONNECTOR STUB CABLE PER HOLE. for protectio at cable slots ad sleeves that are fire-stopped at each floor. 5.o5 Buildig Desig Load Cosideratios: Temporary ad permaet riser cable support must be icluded i riser pathway desigs. Temporary or short-term support occurs durig iitial istallatio ad permaet or log-term support durig the service life of the cable. 5.6 Temporary Load Cosideratios: Whe the cable is beig istalled by hoistig to a upper floor, its etire suspeded weight is carried by the pullig wich located o a upper floor. Durig this operatio whe the wich is located adjacet to the riser opeig, the cable pullig load is trasferred to the split spadrel beam structure. 5.o7 The magitude of the load exerted o the spadrel by the wich ca rage up to 12, pouds of cocetrated force whe two wiches are used i tadem. Therefore, spadrels must be desiged to hadle loads of this magitude durig cable istallatio. Fig. 4 Cable Hole Patters for Various Frames The colum lie requires some type of framig from the structure of the buildig itselfi this framig ca be relatively easily modified to accommodate the sleeves. Ay additioal framig that may be required is at the edge of the buildig floor space ad, therefore, will ot cause ay headroom pealties. Figure 6 illustrates how this ca be doe for two types of framig systems used i buildig costructio. 5.o4 The riser area ca be eclosed by a fire-rated partitio or i a floor-to-ceilig fire-rated shaft, chase, or cabiet. Provisios must be made to keep floor opeigs i shafts, chases, ad cabiets accessible for future cable additios, sealig measures, ad fire-fightig access. most buildigs, the itercolum space will provide walls o the three sides, thus requirig oly oe additioal wall, as show i Fig. 7, for the costructio of a partitio. 5.8 Permaet Load Cosideratios: There are several acceptable techiques for permaetly supportig cables i riser space; however, some of these techiques require mior buildig desig provisios. The three most suitable methods are (1) supportig strad lashed to the cable at 3-foot itervals, (2) Kellems grips placed every third floor, ad (3) cable straps or ties secured to cable racks. 5.9 The strad support method is used for istallatios of log suspeded legths of cables, especially those eclosed i coduit. Oe method of supportig the riser strad is to secure the strad to a support bar ear the ceilig level of the story o which the cable termiates. The strad ca be looped ad tied aroud the bar as illustrated i Fig. 8. geeral, the support strad should be desiged to support a estimated weight of 1 pouds per liear foot of riser cable. The total load of the specific cable legth ad umber of riser cables, alog with the factor of safety Page 5

6 SECTON ,----! t----l!1, P;NEL ---- :1 t- ---QDROP A ~--, r--l H ;;! l-ḻ-- J!; ~ 1, CABLE SLEEVES 1~1 =X -m-i-- t CABLE SLEEVES w ---i-- TO (CROSS BEAMS SPACED AT 6-6 CONCDE WTH GAPS N SLEEVE PATTERN) SECTON A - A Q. FLAT SLAB CONSTRUCTON, ALL FRAMES t CABLE SLEEVES =1 -+i C. BEAM, SLAB ANO GROER CONSTRUCTON FOR PROTECTOR FRAME MODULAR [ ONE OPENNG BLOCKED AT CROSS BEAM EvERY 2 ) NOTE : THE DMENSON OF THE f. OF THE CABLE SLEEVES FROM THE WALL AND THE ASSOCATED STRUCTURE OEPENDS ON THE ASLE SPACE REQuREMENTS AND WDTH OF EACH FRAME. THERE S ALSO THE POSS- BLTY OF MuLTPLE LNEUPS OF FRAMES WTH SLEEVE ON TWO CENTER LNES b. BEAM, SLAB AND GROER CONSTRUCTON FOR ospf a LpCDF Fig. 5 Framig for Cable Holes Below Mai Frames appropriate to the type of costructio*, must be icorporated i the structural member desig. * Live load factors of safety are recommeded by codes of the America Cocrete stitute ad the America stitute of Steel Costructio. 5.1o The Kellems cable grip ca beused to support cables i sleeves or shafts. The floor sleeve protrusio ca serve to hook the cable grips so they ca support the cable below the floor. Figure 9 illustrates a cable grip of this type usig a split rig to support the grip. f shafts are used, grips may also be attached to a support strad which is i tur attached to a support bar as show i Fig. 1. either case, the buildig members will ot geerally be heavily loaded by this system because the supportig loads are distributed more equally, usually at every third floor level Wall-mouted racks ca also be used, with at least three horizotal members per floor level, to support cables without cable grips or strad. The riser cables horizotal support member, cable weight equally o the are secured at each thus distributig the wall. 5.12, Riser Cable stallatio: Riser cables are usually pulled ito place by electric wiches which rage i power up to 1 horsepower 11 Vat, capable of liftig 6 pouds at a speed of approximately 5 feet per miute. Two of these cable pullers ca be placed i tadem to icrease pullig capacity for difficult ad/or log cable istallatios. Raisig the cable provides maximum cotrol for log vertical riser pathways; however, whe a log legth of slack is required o a upper floor, such as o carrier floors, it may be more coveiet to lower the cable dow the riser space. Positioig of the cable reel ad, more importatly, provisio of a adequate brakig system are problems ecoutered whe lowerig riser cables. A height limitatio of o more tha three or four floors is imposed whe usig this method. may cases, the height to which cables ca be Page 6

7 114,, lo. ~..~ 1SS 1, SECTON ! (- ---l i ~lo OD o.,1,1,1 _- EXTEROR WALL FRE RATED SECTON A-A FLAT SLAB CONSTRUCTON BEAM, SLAB, 6 GRDER CONSTRUCTON ART T N4i : lo ;1 l!o\ r - 4 NSDE DAMETER 11 SLEEVES SPACED Jsl - 12 ON CENTER (MNMUM) lo lo 11 lo 11,,,.., ;D,., ~,.,.*..,. :... *b. : 11 o o,, P<AN VE W Fig. 6 Costructio of Riser Opeigs Fig. 7 Riser Space Layout raised is limited by the size of the cable reel that ca be maeuvered ito place Riser Cable Placemet: The riser cable istallatio procedure may be divided ito three phases: (1) pullig, usually less tha 1 hour; (2) temporary suspesio, perhaps lastig over a weeked; ad (3) permaet suspesio, for the service life of the cable. To raise the cable, a pullig lie is attached to a pullig eye, a core hitch, or a cable grip (Kellems grip). With a pullig HAN 4 eye or core hitch, the pullig force is take directly ~ i tesio by the metallic coductors. With the cable grip, the pullig force is trasmitted to the ~ core through the sheath by a pichig actio ad shearig force. For this reaso, cable grips may damage the cable sheath o log or difficult pulls. Fig. 8 Cabe Support at Ceilig Level Page 7

8 ~ SECTON SLT RNG RE5K ON RM OF CONOUT L ROD FOR KNG GRP Fig. 9 Kellems Cable Grip With Split Rig Support (Fire Stop Not Show for Clarity) 6. REFERENCES Sectio Cable Opeigs Desig Stadards Sectio Cable Opeigs 3. Sectio Core Method of 7. Formig Mai Frame Cable Holes 6. Sectio terior Costructio to Restrict Spread of Fire Sectio Sheathig for Cable Opeigs stallatio Geeral Equipmet Requiremets Sectio Coduit System Desig Sectio Cable Etrace Facility System Desig Page 8

9 1SS 1, SECTON 76- STRAND ~ 1/7 HOOK AND EYE TURNBUCKLE WTH 12 TAKEUP ~ SNGLE EYE SPLT RSER CABLE GRP Fig. 1 termediate Cable Grip Support Page 9

10 N CEF CONDUT, RSER, AND HOLE STANDARDS (a) Coduit etraces: (1) Select coduit formatio ad spacig betwee coduits based o cetral office required s. ti:., (2) Plug empty ad occupied ducts i the coduit etraces with stadard rubber duct plugs. (3) Provide a gas vetig chamber that is part of, or is close to, the cetral office buildig for all coduit etraces. (4) Costruct the gas vetig chamber structure to be cosistet with coduit capacity ad the imposed soil-load requiremets. (5) Do ot route plastic coduit or cables through ope below-grade crawl spaces or pits. (b) Cable holes: (1) Provide holes sized to satisfy stub- ad riser-cable desity requiremets. (2) Cosider the icrease i floor slab flexibility resultig from the removal of cocrete for holes. (3) Observe fire safety practices coverig floor opeigs i a cetral office. (c) Riser spaces: (1) Provide riser spaces to satisfy riser-cable requiremets for a duplex CEF desig. (2) Select discrete cable holes based o cable desity requiremets. (3) Cosider the icrease i floor slab flexibility resultig from the removal of cocrete for riser opeigs. (4) Observe fire safety practices coverig floor opeigs i a cetral office.,.j,>,, Y j f