§1755.98 7 CFR Ch. XVII (1–1–99 Edition) · FR 53044, Oct. 21, 1994; 59 FR 66440, Dec. 27, 1994; 60 FR 1712, ... A copy of the ANSI/NFPA 1993 NEC ... Black-Green..... 301–325

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7 CFR Ch. XVII (1–1–99 Edition)§ 1755.98

RUS Bulletin No. Specification No. Date last issued Title of standard or specification

345–154 ............... Form 515g .......... July 1989 ............ RUS specifications and drawings for service entrance and stationprotection installation.

345–180 ............... Form 397a .......... Jan. 1963 ........... RUS specifications for voice frequency repeaters and voice fre-quency repeatered trunks.

345–183 ............... Form 397d .......... June 1970 .......... RUS design specifications for point-to-point microwave radio sys-tems.

345–184 ............... Form 397e .......... May 1971 ........... RUS design specifications for mobile and fixed dial radio tele-phone equipment.

1728F–700 ........... ............................. 9-2-93 ................. RUS Specification for Wood Poles, Stubs and Anchor Logs

[48 FR 57470, Dec. 30, 1983]

EDITORIAL NOTE: For FEDERAL REGISTER citations affecting § 1755.97, see the List of CFRSections Affected in the Finding Aids section of this volume.

§ 1755.98 List of telephone standardsand specifications included in other7 CFR parts.

The following standards and speci-fications are included throughout 7CFR chapter XVII. These standards andspecifications are not incorporated byreference elsewhere in the chapter. Theterms ‘‘RUS form’’, ‘‘RUS standardform’’, ‘‘RUS specification’’, and ‘‘RUSbulletin’’ have the same meanings asthe terms ‘‘REA form’’, ‘‘REA standardform’’, ‘‘REA specification’’, and ‘‘REAbulletin’’, respectively, unless other-wise indicated.

Section Issue date Title

1728.202 9–2–93 RUS Specification forQuality Control and In-spection of TimberProducts.

1755.200 1–26–95 RUS Standard for Splic-ing Copper and FiberOptic Cables.

1755.370 1–19–90 RUS Specification forSeven Wire Galva-nized Steel Strand.

1755.390 6–21–93 RUS Specification forFilled Telephone Ca-bles.

1755.397 3–6–90 RUS Design Specifica-tion for DigitalLightwave Trans-mission Systems, RUSForm 397h.

1755.400through1755.407.

6–2–97 RUS Standard for Ac-ceptance Tests andMeasurements ofTelecommunicationsPlant.

Section Issue date Title

1755.522 6–28–93 RUS General Specifica-tion for Digital, StoredProgram ControlledCentral Office Equip-ment.

1755.525 7–18–94 RUS Form 525, CentralOffice Equipment Con-tract (Including Instal-lation).

1755.700through1755.704.

6–24–96 RUS Specification forAerial Service Wires.

1755.860 12–20–93 RUS Specification forFilled Buried Wires.

1755.870 7–14–94 RUS Specification forTerminating Cables.

1755.890 6–21–93 RUS Specification forFilled Telephone Ca-bles with Expanded In-sulation.

1755.900 8–4–94 RUS Specification forFilled Fiber Optic Ca-bles.

1755.910 11–21–94 RUS Specification forOutside PlantHousings and ServingArea Interface Sys-tems.

[58 FR 41410, Aug. 3, 1993, as amended at 59FR 53044, Oct. 21, 1994; 59 FR 66440, Dec. 27,1994; 60 FR 1712, Jan. 5, 1995; 60 FR 5097, Jan.26, 1995; 61 FR 26074, May 24, 1996; 62 FR 23959,May 2, 1997]

§§ 1755.99—1755.199 [Reserved]

§ 1755.200 RUS standard for splicingcopper and fiber optic cables.

(a) Scope. (1) This section describesapproved methods for splicing plasticinsulated copper and fiber optic cables.Typical applications of these methodsinclude aerial, buried, and undergroundsplices.

(2) American National Standard In-stitute/National Fire Protection Asso-ciation (ANSI/NFPA) 70, 1993 NationalElectrical Code (NEC) referenced in

VerDate 03<MAR>99 11:28 Mar 18, 1999 Jkt 183020 PO 00000 Frm 00388 Fmt 8010 Sfmt 8010 Y:\SGML\183020T.XXX pfrm04 PsN: 183020T

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Rural Utilities Service, USDA § 1755.200

this section is incorporated by ref-erence by RUS. This incorporation byreference was approved by the Directorof the Federal Register in accordancewith 5 U.S.C. 552(a) and 1 CFR part 51.A copy of the ANSI/NFPA 1993 NECstandard is available for inspectionduring normal business hours at RUS,room 2845, U.S. Department of Agri-culture, Washington, DC 20250–1500 orat the Office of the Federal Register,800 North Capitol Street, NW., suite700, Washington, DC. Copies are avail-able from NFPA, Batterymarch Park,Quincy, Massachusetts 02269, telephonenumber 1 (800) 344–3555.

(3) American National Standard In-stitute/Institute of Electrical and Elec-tronics Engineers, Inc. (ANSI/IEEE),1993 National Electrical Safety Code(NESC) referenced in this section is in-corporated by reference by RUS. Thisincorporation by reference was ap-proved by the Director of the FederalRegister in accordance with 5 U.S.C.552(a) and 1 CFR part 51. A copy of theANSI/IEEE 1993 NESC standard isavailable for inspection during normalbusiness hours at RUS, room 2845, U.S.Department of Agriculture, Wash-ington, DC 20250–1500 or at the Office ofthe Federal Register, 800 North CapitolStreet, NW., suite 700, Washington, DC.Copies are available from IEEE ServiceCenter, 455 Hoes Lane, Piscataway,New Jersey 08854, telephone number 1(800) 678–4333.

(b) General. (1) Only Rural UtilitiesService (RUS) accepted filled cable andsplicing materials shall be used on out-side plant projects financed by RUS.

(2) The installation instructions pro-vided by the manufacturer of splicingmaterials shall be followed exceptwhere those instructions conflict withthe procedures specified in this section.

(3) Precautions shall be taken to pre-vent the ingress of moisture and othercontaminants during all phases of thesplicing installation. When anuncompleted splice must be left unat-tended, it shall be sealed to prevent theingress of moisture and other contami-nants.

(4) Minor sheath damage during con-struction may be repaired if the repairis completed immediately and ap-proved by the borrower’s resident

project representative. Minor damageis typically repaired by:

(i) Scuffing the cable sheath associ-ated with the damaged area;

(ii) Applying several layers of DRtape over the scuffed and damagedarea;

(iii) Applying several layers of plas-tic tape over the DR tape; and

(iv) If damage is severe enough torupture the cable shield, a splice clo-sure shall be installed.

(5) All splice cases installed on RUStoll trunk and feeder cables shall befilled, whether aerial, buried, or under-ground.

(c) Splicing considerations for coppercables—(1) Preconstruction testing. It isdesirable that each reel of cable betested for grounds, opens, shorts,crosses, and shield continuity beforethe cable is installed. However, manu-facturer supplied test results are ac-ceptable. All cable pairs shall be freefrom electrical defects.

(2) Handling precautions. The cablemanufacturer’s instructions con-cerning pulling tension and bending ra-dius shall be observed. Unless the cablemanufacturer’s recommendation ismore stringent, the minimum bendingradius shall be 10 times the cable di-ameter for copper cables and 20 timesthe cable diameter for fiber optic ca-bles.

(3) Cable sheath removal. (i) Thelength of cable sheath to be removedshall be governed by the type of splic-ing hardware used. Follow the splicecase manufacturer’s recommendations.For pedestals or large pair count splicehousings, consider removing enoughcable sheath to allow the conductors toextend to the top of the pedestal andthen to hang downward to approxi-mately 15 centimeters (cm) (6 inches(in.)) above the baseplate.

(ii) Caution shall be exercised toavoid damaging the conductor insula-tion when cutting through the cableshield and removing the shield. Sharpedges and burrs shall be removed fromthe cut end of the shield.

(4) Shield bonding and grounding. Forpersonnel safety, the shields of the ca-bles to be spliced shall be bonded to-gether and grounded before splicing ac-tivities are started. (See paragraphs(g)(2), and (g)(5)(i) through (g)(5)(iii) of


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this section for final bonding andgrounding provisions.)

(5) Binder group identification. (i)Color coded plastic tie wraps shall beplaced loosely around each bindergroup of cables before splicing oper-ations are attempted. The tie wrapsshall be installed as near the cablesheath as practicable and shall con-form to the same color designations asthe binder ribbons. Twisted wire pig-tails shall not be used to identify bind-er groups due to potential transmissiondegradation.

(ii) The standard insulation colorcode used to identify individual cablepairs within 25-pair binder groups shallbe as shown in Table 1:

TABLE 1—CABLE PAIR IDENTIFICATION WITHINBINDER GROUPS

Pair No.Color

Tip Ring

1 ................................................ White ........... Blue.2 ................................................ White ........... Orange.3 ................................................ White ........... Green.4 ................................................ White ........... Brown.5 ................................................ White ........... Slate.6 ................................................ Red .............. Blue.7 ................................................ Red .............. Orange.8 ................................................ Red .............. Green.9 ................................................ Red .............. Brown.10 .............................................. Red .............. Slate.11 .............................................. Black ........... Blue.12 .............................................. Black ........... Orange.13 .............................................. Black ........... Green.14 .............................................. Black ........... Brown.15 .............................................. Black ........... Slate.16 .............................................. Yellow .......... Blue.17 .............................................. Yellow .......... Orange.18 .............................................. Yellow .......... Green.19 .............................................. Yellow .......... Brown.20 .............................................. Yellow .......... Slate.21 .............................................. Violet ........... Blue.22 .............................................. Violet ........... Orange.23 .............................................. Violet ........... Green.24 .............................................. Violet ........... Brown.25 .............................................. Violet ........... Slate.

(iii) The standard binder ribbon colorcode used to designate 25-pair bindergroups within 600-pair super units shallbe as shown in Table 2:

TABLE 2—CABLE BINDER GROUP IDENTIFICATION

Group No. Color of bindings Group paircount

1 ................................... White-Blue ................. 1–252 ................................... White-Orange ............ 26–503 ................................... White-Green .............. 51–754 ................................... White-Brown .............. 76–1005 ................................... White-Slate ................ 101–1256 ................................... Red-Blue .................... 126–1507 ................................... Red-Orange ............... 151–1758 ................................... Red-Green ................. 176–200

TABLE 2—CABLE BINDER GROUPIDENTIFICATION—Continued

Group No. Color of bindings Group paircount

9 ................................... Red-Brown ................. 201–22510 ................................. Red-Slate ................... 226–25011 ................................. Black-Blue ................. 251–27512 ................................. Black-Orange ............. 276–30013 ................................. Black-Green ............... 301–32514 ................................. Black-Brown .............. 326–35015 ................................. Black-Slate ................ 351–37516 ................................. Yellow-Blue ................ 376–40017 ................................. Yellow-Orange ........... 401–42518 ................................. Yellow-Green ............. 426–45019 ................................. Yellow-Brown ............. 451–47520 ................................. Yellow-Slate ............... 476–50021 ................................. Violet-Blue ................. 501–52522 ................................. Violet-Orange ............ 526–55023 ................................. Violet-Green .............. 551–57524 ................................. Violet-Brown .............. 576–600

(iv) Super-unit binder groups shall beidentified in accordance with Table 3:

TABLE 3—SUPER-UNIT BINDER COLORS

Pair numbers Binder color

1–600 ............................................................... White.601–1200 ......................................................... Red.1201–1800 ....................................................... Black.1801–2400 ....................................................... Yellow.2401–3000 ....................................................... Violet.3001–3600 ....................................................... Blue.3601–4200 ....................................................... Orange.4201–4800 ....................................................... Green.4801–5400 ....................................................... Brown.5401–6000 ....................................................... Slate.

(v) Service pairs in screened cablesshall be identified in accordance withTable 4:

TABLE 4—SCREENED CABLE SERVICE PAIRIDENTIFICATION

Service pair No.Color

Tip Ring

1 ................................................ White ........... Red.2 ................................................ White ........... Black.3 ................................................ White ........... Yellow.4 ................................................ White ........... Violet.

Red .............. Black.6 ................................................ Red .............. Yellow.7 ................................................ Red .............. Violet.8 ................................................ Black ........... Yellow.9 ................................................ Black ........... Violet.

(6) Cleaning conductors. It is not nec-essary to remove the filling compoundfrom cable conductors before splicing.However, it is permissible to wipe indi-vidual conductors with clean papertowels or clean cloth rags. No cleaningchemicals, etc., shall be used. Cautionshall be exercised to maintain indi-vidual cable pair and binder group


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identity. Binder group identity shall bemaintained by using color coded plas-tic tie wraps. Individual pair identi-fication shall be maintained by care-fully twisting together the two conduc-tors of each pair.

(7) Expanded plastic insulated con-ductor (PIC) precautions. Solid PIC andexpanded (foam or foam skin) PIC arespliced in the same manner, using thesame tools and materials and, in gen-eral, should be treated the same. How-ever, the insulation on expanded PIC ismuch more fragile than solid PIC.Twisting or forming expanded PIC intoextremely compact splice bundles andapplying excessive amounts of tensionwhen tightening tie wraps causes shin-ers and, thus shall be avoided.

(8) Splice connectors. (i) Only RUS ac-cepted filled splice connectors shall beused on outside plant projects financedby RUS.

(ii) Specialized connectors are avail-able for splicing operations such asbutt splices, in line splices, bridge taps,clearing and capping, and multiple pairsplicing operations. The splice con-nector manufacturer’s recommenda-tions shall be followed concerning con-nector selection and use.

(iii) Caution shall be exercised tomaintain conductor and pair associa-tion both during and after splicing op-erations.

(iv) Splicing operations that involvepairs containing working services shallutilize splice connectors that permitsplicing without the interruption ofservice.

(9) Piecing out conductors. Conductorsmay be pieced-out to provide addi-tional slack or to repair damaged con-ductors. However, the conductors shallbe pieced-out with conductors havingthe same gauge and type and color ofinsulation. The conductors used forpiecing-out shall be from cables havingRUS acceptance.

(10) Splice organization. Spliced pairbundles shall be arranged in firm lay-ups with minimum conductor tensionin accordance with the manufacturer’sinstructions.

(11) Binder tape. Perforated nonhygro-scopic and nonwicking binder tapeshould be applied to splices housed infilled splice cases. The binder tape al-lows the flow of filling compound while

holding the splice bundles near the cen-ter of the splice case to allow adequatecoverage of filling compound.

(12) Cable tags. Cables shall be identi-fied by a tag indicating the cable man-ufacturer’s name, cable size, date ofplacement, and generic route informa-tion. Information susceptible tochanges caused by future cable throwsand rearrangements should not be in-cluded. Tags on load coil stubs shall in-clude the serial number of the coilcase, the manufacturer’s name, and theinductance value.

(13) Screened cable. Screened PICcable is spliced in the same manner asnonscreened PIC cable. However, spe-cial considerations are necessary dueto differences in the cable design. Thetransmit and receive bundles of thecable shall be separated and one of thebundles shall be wrapped with shieldingmaterial in accordance with the cablemanufacturer’s recommendations.When acceptable to the cable manufac-turer, it is permissible to use either thescrap screening tape removed from thecable during the sheath opening proc-ess provided the screening tape is edgecoated or new pressure sensitive alu-minum foil tape over polyethylenetape.

(14) Service wire connections. (i) Buriedservice wires may be spliced directly tocable conductors inside pedestals usingthe same techniques required forbranch cables. Buried service wiresmay also be terminated on terminalblocks inside pedestals in areas wherehigh service order activity or fixedcount cable administration policies re-quire terminal blocks. However, onlyRUS accepted terminal blocksequipped with grease or gel filled ter-minations to provide moisture and cor-rosion resistance shall be used.

(ii) Only filled terminal blocks hav-ing RUS acceptance shall be used onaerial service wire connections.

(15) Copper cable testing. Copper cabletesting shall be performed in accord-ance with RUS Bulletin 345–63, ‘‘RUSStandard for Acceptance Tests andMeasurements of Telephone Plant,’’PC–4, (Incorporated by reference at§ 1755.97).

(16) Cable acceptance. Installed cableshall be tested and pass the inventoryand acceptance testing specified in the


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Telephone System Construction Con-tract (Labor and Materials), RUS Form515. The tests and inspections shall bewitnessed by the borrower’s residentproject representative. All conductorsshall be free from grounds, shorts,crosses, splits, and opens.

(d) Splice arrangements for copper ca-bles—(1) Service distribution closures. (i)Ready access closures permit cablesplicing activities and the installationof filled terminal blocks for servicewire connections in the same closure.Ready access designs shall allow serv-ice technicians direct access to thecable core as well as the terminalblock.

(ii) Fixed count terminals shall re-strict service technician access to thecable core. Predetermined cable pairsshall be spliced to the terminal leads orstub cable in advance of service assign-ments.

(2) Aerial splices. Aerial splice casesaccommodate straight splices, branchsplices, load coils, and service distribu-tion terminals. Aerial splicing arrange-ments having more than 4 cablesspliced in the same splice case are notrecommended. Stub cabling to a secondsplice case to avoid a congested spliceis acceptable.

(3) Buried splices. (i) Direct buriedsplice cases accommodate straightsplices, branch splices, and load coils.Direct buried splices shall be filled andshall be used only when above groundsplicing in pedestals is not practicable.

(ii) A treated plank or equivalentshall be placed 15 cm (6 in.) above theburied splice case to prevent damage tothe splice case from future digging.Where a firm base for burying a splicecannot be obtained, a treated plank orequivalent shall be placed beneath thesplice case.

(iii) Each buried splice shall be iden-tified for future locating. One methodof marking the splice point is the useof a warning sign. Another method isthe burying of an electronic locatingdevice.

(4) BD-type pedestals. (i) BD-type ped-estals are housings primarily intendedto house, organize, and protect cableterminations incorporating splice con-nectors, ground lugs, and load coils.Activities typically performed in ped-estals are cable splicing, shield bonding

and grounding, loading, and connectionof subscriber service drops.

(ii) The recommended splice capac-ities for BD-type pedestals are shownin Table 5. However, larger size ped-estals are permissible if service re-quirements dictate their usefulness.Table 5 is as follows:

TABLE 5—SPLICE CAPACITIES FOR BD-TYPEPEDESTALS

Pedestal type

Maximum straightsplice pair capac-

ity using singlepair connectorsor multiple pairsplice modules

Maximum loadsplice pair ca-pacity usingsingle pair

connectors ormultiple pair

splice modules(see note 1)

BD3, BD3A ................... 100 Pair .............. 50 Pair.BD4, BD4A ................... 200 Pair .............. 100 Pair.BD5, BD5A ................... 600 Pair .............. 300 Pair.BD7 ............................... 1200 Pair ............ 600 Pair.BD14, BD14A ............... 100 Pair .............. 50 Pair.BD15, BD15A ............... 400 Pair .............. 200 Pair.BD16, BD16A ............... 600 Pair .............. 300 Pair.

Note 1: This table refers to load coil cases that are to be di-rect buried with stub cables extending into the pedestal forsplicing. Requirements involving individual coil arrangementsinside the pedestal should be engineered on a case-by-casebasis.

(iii) Special distribution pedestalshaving a divider plate for mountingfilled terminal blocks are available.Distribution pedestals are alsoequipped with service wire channels forinstallation of buried service wireswithout disturbing the cabling andgravel inside the base of the pedestal.Distribution pedestals are rec-ommended in locations where the con-nection of service wires is required.

(5) Large pair count splice housings.Large pair count splice housings arerecommended for areas not suitable forman- holes. The recommended capac-ities are shown in Table 6:

TABLE 6—SPLICE CAPACITIES FOR LARGECOUNT HOUSINGS

Housing type

Maximum straightsplice pair capacity

using single pair con-nectors or multiplepair splice modules

Maximum loadsplice pair capac-

ity using singlepair connectorsor multiple pairsplice modules

(see note 1)

BD 6000 ............ 6,000 Pair .................. 3,000 Pair.BD 8000 ............ 8,000 Pair .................. 4,000 Pair.BD 10000 .......... 10,000 Pair ................ 5,000 Pair.

(6) Pedestal restricted access inserts.Restricted access inserts may be used


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to protect splices susceptible to unnec-essary handling where subsequent workactivities are required or expected tooccur after splices have been com-pleted. Restricted access inserts also

provide moisture protection in areassusceptible to temporary flooding. Atypical restricted access insert isshown in Figure 1:

(7) Serving Area Interface (SAI) Sys-tems. SAI systems provide the cross-connect point between feeder and dis-tribution cables. Connection of feederto distribution pairs is accomplishedby placing jumpers between connectingblocks. Only RUS accepted connecting

blocks having grease or gel filled ter-minations to provide moisture and cor-rosion resistance shall be used.

(8) Buried cable splicing arrangements.Typical buried cable splicing arrange-ments are illustrated in Figures 2through 5:


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399



400



401


(9) Underground splices (manholes).Underground splice cases accommodatestraight splices, branch splices, andload coils. Underground splices shall befilled.

(10) Central office tip cable splices. (i)Filled cable or filled splices are notrecommended for use inside central of-fices, except in cable vault locations.Outside plant cable sheath and cablefilling compound are susceptible to fireand will support combustion. Fire,smoke, and gases generated by these

materials during burning are detri-mental to telephone switching equip-ment.

(ii) Tip cables should be spliced in acable vault. However, as a last resort,tip cables may be spliced inside a cen-tral office if flame retardant splicecases or a noncombustible central of-fice splice housing is used to containthe splice.

(iii) Splices inside the central officeshall be made as close as practical to


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the point where the outside plant ca-bles enter the building. Except in cablevault locations, outside plant cableswithin the central office shall bewrapped with fireproof tape or enclosedin noncombustible conduit.

(e) Splicing considerations for fiberoptic cables—(1) Connection characteris-tics. Splicing efficiency between opticalfibers is a function of light loss acrossthe fiber junctions measured in deci-bels (dB). A loss of 0.2 dB in a splice

corresponds to a light transmission ef-ficiency of approximately 95.5 percent.

(2) Fiber core alignment. Fiber splicingtechniques shall be conducted in such amanner that the cores of the fibers willbe aligned as perfectly as possible toallow maximum light transmissionfrom one fiber to the next. Withoutproper alignment, light will leave thefiber core and travel through the fibercladding. Light outside the fiber core isnot a usable light signal. Core mis-alignment is illustrated in Figure 6:

(3) Splice loss. (i) Splice loss can alsobe caused by fiber defects such as non-identical core diameters, cores not in

center of the fiber, and noncircularcores. Such defects are depicted in Fig-ure 7:


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(ii) Undesirable splice losses arecaused by poor splicing techniques in-cluding splicing irregularities such as

improper cleaves and dirty splices.Typical cleave problems are illustratedin Figure 8:


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(4) Handling precautions. The fol-lowing precautions shall be observed:

(i) Avoid damaging the cable duringhandling operations prior to splicing.Minor damage may change the trans-mission characteristics of the fibers tothe extent that the cable section willhave to be replaced;

(ii) The cable manufacturer’s rec-ommendations concerning pulling ten-sion shall be observed. The maximumpulling tension for most fiber opticcable is 2669 newtons (600 pound-force);

(iii) The cable manufacturer’s rec-ommendations concerning bending ra-dius shall be observed. Unless the cablemanufacturer’s recommendation ismore stringent, the minimum bendingradius for fiber optic cable shall be 20times the cable diameter;

(iv) The cable manufacturer’s rec-ommendations concerning buffer tubebending radius shall be observed. Un-less the cable manufacturer’s rec-ommendation is more stringent, theminimum bending radius for buffertubes is usually between 38 millimeters(mm) (1.5 in.) and 76 mm (3.0 in.). Thebending limitations on buffer tubes areintended to prevent kinking. Buffertube kinking may cause excessive opti-cal loss or fiber breakage; and

(v) Handle unprotected glass fiberscarefully to avoid introducing flawssuch as scratched or broken fibers.

(5) Personnel safety. The followingsafety precautions shall be observed:

(i) Safety glasses shall be worn whenhandling glass fibers;


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(ii) Never view open-ended fibers withthe naked eye or a magnifying device.Improper viewing of a fiber end that istransmitting light may cause irrep-arable eye damage; and

(iii) Dispose of bare scrap fibers byusing the sticky side of a piece of tapeto pick up and discard loose fiber ends.Fiber scraps easily penetrate the skinand are difficult to remove.

(6) Equipment requirements. (i) Fiberoptic splices shall be made in areaswhere temperature, humidity, andcleanliness can be controlled. Both fu-sion and mechanical splicing tech-niques may require a splicing vehicleequipped with a work station that willallow environmental control.

(ii) Both fusion and mechanical splic-ing techniques are permitted on RUSfinanced projects. When using the me-chanical splicing technique, only RUSaccepted mechanical fiber optic spliceconnectors can be used.

(iii) Fusion splicing machines shallbe kept in proper working condition.Regular maintenance in accordancewith the machine manufacturer’s rec-ommendations shall be observed.

(iv) Mechanical splicing tools shallbe in conformance with the tool manu-facturer’s recommendations.

(v) An optical time domain reflec-tometer (OTDR) shall be used for test-ing splices. The OTDR shall be sta-tioned at the central office or launchpoint for testing individual splices asthey are made and for end-to-end sig-nature tests for the fiber optic link.

(vi) An optical power meter shall beused for end-to-end cable acceptancetests.

(vii) A prerequisite for the successfulcompletion of a fiber optic splicing en-deavor is the presence of a talk circuitbetween the splicing technician in thesplicing vehicle and the operator of theOTDR in the central office. The splic-ing technician and the OTDR operatorshall have access to communicationswith each other in order to inform eachother as to:

(A) Which splices meet the loss objec-tives;

(B) The sequence in which buffertubes and fibers are to be selected forsubsequent splicing operations; and

(C) The timing required for the per-formance of OTDR testing to prevent

making an OTDR test at the same timea splice is being fused.

(7) Cable preparation. (i) Engineeringwork prints shall prescribe the cableslack needed at splice points to reachthe work station inside the splicing ve-hicle. Consideration should be given tothe slack required for future mainte-nance activity as well as initial con-struction activities. The required slackmay be different for each splice point,depending on the site logistics. How-ever, the required slack is seldom lessthan 15 meters (50 feet). The amount ofslack actually used shall be recordedfor each splice point to assist futuremaintenance and restoration efforts.

(ii) The splice case manufacturer’srecommendations concerning theamount of cable sheath to be removedshall be followed to facilitate splicingoperations. The length of the sheathopening shall be identified with a wrapof plastic tape.

(iii) If the cable contains a rip cord,the cable jacket shall be ring cut ap-proximately 15 cm (6 in.) from the endand the 15 cm (6 in.) of cable jacketshall be removed to expose the rip cord.The rip cord shall be used to slit thejacket to the tape mark.

(iv) If the cable does not contain a ripcord, the cable jacket shall be slitusing a sheath splitter. No cuts shallbe made into the cable core nor shallthe buffer tubes be damaged.

(v) If the cable contains an armorsheath, the outer jacket shall beopened along the slit and the jacketshall be removed exposing the armorsheath. The armor shall be separatedat the seam and pulled from the cableexposing the inner jacket. The armorshall be removed making allowancesfor a shield bond connector. The innersheath shall be slit using a sheathsplitter or rip cord. The cable coreshall not be damaged nor shall there beany damage to the buffer tubes. Thejacket shall be peeled back and cut atthe end of the slit. The exposed buffertubes shall not be cut, kinked, or bent.

(vi) After the cable sheath has beenremoved, the binder tape shall be re-moved from the cable. The cable shallnot be crushed or deformed.

(vii) The buffer tubes shall beunstranded one at a time. The buffertubes shall not be kinked.


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(viii) If the cable is equipped with astrength member, the strength membershall be cut to the length recommendedby the splice case manufacturer.

(ix) Each buffer tube shall be in-spected for kinks, cuts, and flat spots.If damage is detected, an additionallength of cable jacket shall be removedand all of the buffer tubes shall be cutoff at the point of damage.

(x) The cable preparation sequenceshall be repeated for the other cableend.

(8) Shield bonding and grounding. Forpersonnel safety, the shields and me-tallic strength members of the cablesto be spliced shall be bonded togetherand grounded before splicing activitiesare started. (See paragraphs (g)(4), and(g)(5)(i) through (g)(5)(iii) of this sec-tion for final bonding and groundingprovisions).

(9) Fiber optic color code. The standardfiber optic color code for buffer tubesand individual fibers shall be as shownin Table 7:

TABLE 7.—FIBER AND BUFFER TUBEIDENTIFICATION

Buffer tube and fiber No. Color

1 ....................................... Blue.2 ....................................... Orange.3 ....................................... Green.4 ....................................... Brown.5 ....................................... Slate.6 ....................................... White.7 ....................................... Red.8 ....................................... Black.9 ....................................... Yellow.

10 ....................................... Violet.11 ....................................... Rose.12 ....................................... Aqua.13 ....................................... Blue/Black Tracer.14 ....................................... Orange/Black Tracer.15 ....................................... Green/Black Tracer.16 ....................................... Brown/Black Tracer.17 ....................................... Slate/Black Tracer.18 ....................................... White/Black Tracer.19 ....................................... Red/Black Tracer.20 ....................................... Black/Yellow Tracer.21 ....................................... Yellow/Black Tracer.22 ....................................... Violet/Black Tracer.23 ....................................... Rose/Black Tracer.24 ....................................... Aqua/Black Tracer.

(10) Buffer tube removal. (i) The splicecase manufacturer’s recommendationshall be followed concerning the totallength of buffer tube to be removed.Identify the length to be removed withplastic tape.

(ii) Experiment with a scrap buffertube to determine the cutting tool ad-

justment required to ring cut a buffertube without damaging the fibers.

(iii) Buffer tubes shall be removed bycarefully ring cutting and removing ap-proximately 15 to 46 cm (6 to 18 in.) ofbuffer tube at a time. The process shallbe repeated until the required length ofbuffer tube has been removed, includ-ing the tape identification marker.

(11) Coated fiber cleaning. (i) Eachcoated fiber shall be cleaned. The cablemanufacturer’s recommendations shallbe followed concerning the solvent re-quired to clean the coated fibers. Rea-gent grade isopropyl alcohol is a com-monly used cleaning solvent.

(ii) A tissue or cotton ball shall besoaked in the recommended cleaningsolvent and the coated fibers shall becarefully wiped one at a time using aclean tissue or cotton ball for eachcoated fiber. Caution shall be exercisedto avoid removing the coloring agentfrom the fiber coating.

(12) Fiber coating removal. (i) Fibercoatings shall be removed. In accord-ance with the splicing method used,the splice case manufacturer’s rec-ommendation shall be followed con-cerning the length of fiber coating tobe removed.

(ii) The recommended length of fibercoating shall be removed only on thetwo fibers to be spliced. Fiber coatingremoval shall be performed on a one-fiber-at-a-time basis as each splice isprepared.

(13) Bare fiber cleaning. After the fibercoating has been removed, the bare fi-bers shall be cleaned prior to splicing.Each fiber shall be wiped with a cleantissue or cotton ball soaked with thecleaning solvent recommended by thecable manufacturer. The bare fibershall be wiped one time to minimizefiber damage. Aggressive wiping ofbare fiber shall be avoided as it lowersthe fiber tensile strength.

(14) Fiber cleaving. Cleaving toolsshall be clean and have sharp cuttingedges to minimize fiber scratches andimproper cleave angles. Cleaving toolsthat are recommended by the manufac-turer of the splicing system shall beused.

(15) Cleaved fiber handling. Thecleaved and cleaned fiber shall not beallowed to touch other objects and


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shall be inserted into the splicing de-vice.

(16) Completion of the splice. (i) In ac-cordance with the method of splicingselected by the borrower, the spliceshall be completed by either fusing thesplice or by applying the mechanicalconnector.

(ii) Each spliced fiber shall be routedthrough the organizer tray one at atime as splices are completed. The fi-bers shall be organized one at a time toprevent tangled spliced fibers. Thesplice case manufacturer’s rec-ommendation shall be followed con-cerning the splice tray selection.

(17) Fiber optic testing. Fiber optictesting shall be performed in accord-ance with RUS Bulletin 345–63, ‘‘RUSStandard for Acceptance Tests and

Measurements of Telephone Plant,’’PC–4, (Incorporated by reference at§ 1755.97).

(18) Cable acceptance. Installed cableshall be tested and pass the inventoryand acceptance testing specified in theTelephone System Construction Con-tract (Labor and Materials), RUS Form515. The tests and inspections shall bewitnessed by the borrower’s residentproject representative.

(f) Splice arrangements for fiber opticcables—(1) Aerial splices. Cable slack ataerial splices shall be stored either onthe messenger strand, on the pole, orinside a pedestal at the base of thepole. A typical arrangement for thestorage of slack cable at aerial splicesis shown in Figure 9:


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(2) Buried splices. Buried splices shallbe installed in handholes to accommo-date the splice case and the requiredsplicing slack. An alternative to the

handhole is a pedestal specifically de-signed for fiber optic splice cases. Typ-ical arrangements for buried cablesplices are shown in Figures 10 and 11:


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(3) Underground manhole splices. Un-derground splices shall be stored inmanholes on cable hooks and racks fas-

tened to the manhole wall. The cableslack shall be stored on cable hooksand racks as shown in Figure 12:


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(4) Central office cable entrance. (i)Filled cable or filled splices are notrecommended for use inside central of-fices except in cable vault locations.Outside plant cable sheath and cablefilling compound are susceptible to fireand will support combustion. Fire,smoke, and gases generated by thesematerials during burning are detri-mental to telephone switching equip-ment.

(ii) As a first choice, the outsideplant fiber optic cable shall be splicedto an all-dielectric fire retardant cablein a cable vault with the all-dielectriccable extending into the central officeand terminating inside a fiber patchpanel.

(iii) As a second choice, the outsideplant cable may be spliced inside thecentral office if a flame retardant fiberoptic splice case or a noncombustiblecentral office splice housing equippedwith organizer trays is used to containthe splice.

(iv) In cases referenced in paragraphs(f)(4)(ii) and (f)(4)(iii) of this section, asa minimum the fire retardant all-di-electric cable used to provide the con-nection between the cable entrancesplice and the fiber patch panel shallbe listed as Communication RiserCable (Type CMR) in accordance withSections 800–50 and 800–51(b) of the 1993National Electrical Code.

(v) Splices inside the central officeshall be made as close as practicable to


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the point where the outside plant ca-bles enter the building. Except in cablevault locations, outside plant cableswithin the central office shall bewrapped with fireproof tape or enclosedin noncombustible conduit.

(g) Bonding and grounding fiber opticcable, copper cable, and copper servicewire—(1) Bonding. Bonding is elec-trically connecting two or more metal-lic items of telephone hardware tomaintain a common electrical poten-tial. Bonding may involve connectionsto another utility.

(2) Copper cable shield bond connec-tions. (i) Cable shields shall be bondedat each splice location. Only RUS ac-cepted cable shield bond connectors

shall be used to provide bonding andgrounding connections to metalliccable shields. The shield bond con-nector manufacturer’s instructionsshall be followed concerning installa-tion and use.

(ii)(A) Shield bonding conductorsshall be either stranded or braidedtinned copper wire equivalent to a min-imum No. 6 American Wire Gauge(AWG) and shall be RUS accepted. Theconductor connections shall be tinnedor of a compatible bimetallic design toavoid corrosion problems associatedwith dissimilar metals. The number ofshield bond connectors required perpair size and gauge shall be as shown inTable 8:

TABLE 8.—SHIELD BOND CONNECTORS PER PAIR SIZE AND GAUGE

19 AWGPair size and gauge No. of shield

bond connectors22 AWG 24 AWG 26 AWG

0–25 0–100 0–150 0–200 150–100 150–300 200–400 300–600 2

150–200 400–600 600–900 900–1500 3300–600 900–1200 1200–2100 1800–3600 4

(B) It is permissible to strap acrossthe shield bond connectors of severalcables with a single length of braidedwire. However, both ends of the braidshall be terminated on the pedestalground bracket to provide a bonding

loop. Shield bond connection methodsfor individual cables are shown in Fig-ures 13 through 15, and the bonding ofseveral cables inside a pedestal usingthe bonding loop is shown in Figure 16:


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(3) Buried service wire shield bond con-nections. Buried service wire shieldsshall be connected to the pedestalbonding and grounding system. Typicalburied service wire installations areshown in Figures 17 and 18. In additionto the methods referenced in Figures 17

and 18, the shields of buried servicewires may also be connected to thepedestal bonding and grounding systemusing buried service wire bonding har-nesses listed on Page 3.3.1, Item ‘‘gs-b,’’of RUS Bulletin 1755I–100. RUS Bulletin1755I–100 may be purchased from the


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Superintendent of Documents, U.S.Government Printing Office, Wash-ington, DC 20402. When those harnessesare used they shall be installed in ac-

cordance with the manufacturer’s in-structions. Figures 17 and 18 are as fol-lows:


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(4) Fiber optic cable bond connections.(i) The cable shield and metallicstrength members shall be bonded ateach splice location. Only RUS accept-ed fiber optic cable shield bond connec-tors shall be used to provide bondingconnections to the metallic cableshields. The shield bond connectormanufacturer’s instructions shall befollowed concerning installation anduse.

(ii) Shield bonding conductors shallbe either stranded or braided tinnedcopper wire equivalent to a minimum

No. 6 American Wire Gauge (AWG) andshall be RUS accepted. The conductorconnections shall be tinned or of acompatible bimetallic design to avoidcorrosion problems associated with dis-similar metals.

(5) Grounding. (i) Grounding is elec-trically connecting metallic telephonehardware to a National Electrical Safe-ty Code (NESC) acceptable groundingelectrode. Acceptable grounding elec-trodes are defined in the Rule 99A ofthe NESC.


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(ii) The conductor used for groundingmetallic telephone hardware shall be aminimum No. 6 AWG solid, bare, cop-per conductor.

(iii) For copper and fiber optic cableplant, all cable shields, all metallicstrength members, and all metallichardware shall be:

(A) Grounded at each splice locationto a driven grounding electrode(ground rod) of:

(1) At least 1.5 meters (5 feet) inlength where the local frost level isnormally less than 0.30 meters (1 foot)deep; or

(2) At least 2.44 meters (8 feet) inlength where the local frost level isnormally 0.30 meters (1 foot) or deeper;and

(B) Bonded to a multi-groundedpower system neutral when the spliceis within 1.8 meters (6 feet) of access tothe grounding system of the multi-grounded neutral system. Bonding tothe multi-grounded neutral of a par-allel power line may help to minimizetelephone interference on long expo-sures with copper cable plant. Consid-eration, thus, should be given to com-pleting such bonds, at least four (4)times each mile, when splices aregreater than 1.8 meters (6 feet) but less

than 4.6 meters (15 feet) from access tothe multi-grounded neutral.

(6) Bonding and grounding splice cases.(i) Splice cases are equipped with bond-ing and grounding devices to ensurethat cable shields and metallicstrength members maintain electricalcontinuity during and after cable splic-ing operations. The splice case manu-facturer’s recommendations shall befollowed concerning the bonding andgrounding procedures. Conductors usedfor bonding shall be either stranded orbraided tinned copper wire equivalentto 6 AWG. Conductors used for ground-ing shall be a solid, bare, copper wireequivalent to minimum No. 6 AWG.

(ii) Buried splice cases installed in ei-ther handholes or pedestals shall begrounded such that the cable shieldgrounds are attached to a commonground connection that will allow thelifting of a ground on the cable shieldin either direction to permit efficientcable locating procedures. As a firstchoice, buried grounding conductor(s)shall be bare. However, if two or moregrounding conductors are buried in thes they shall be insulated to avoidshorts when a locating tone is applied.

(iii) A typical bonding and groundingmethod for fiber optic splices is shownin Figure 19:


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(7) Bonding and grounding central of-fice cable entrances. The RUS Tele-communications Engineering and Con-struction Manual (TE&CM) Section 810provides bonding and grounding guid-ance for central office cable entrances.Splicing operations shall not be at-tempted before all metallic cable shield

and strength members are bonded andgrounded.

[60 FR 5097, Jan. 26, 1995; 60 FR 9079, Feb. 16,1995]
