Standard for Splicing Copper and Fiber Optic Cables

DEPARTMENT OF AGRICULTURE

Rural Utilities Service

7 CFR Part 1755

Standard for Splicing Copper and Fiber Optic Cables

AGENCY: Rural Utilities Service, USDA.

ACTION: Final rule.

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SUMMARY: The Rural Utilities Service (RUS) hereby amends its

regulations on telecommunications standards and specifications for

materials, equipment and construction. The revised standard will update

the splicing methods and materials used for splicing copper cables

brought about through technological advancements over the past fifteen

years and incorporate a section into the standard dealing with the

splicing methods and materials used to splice fiber optic cables.

DATES: Effective date: February 27, 1995.

Incorporation by reference: Incorporation by reference of certain

publications listed in this final rule is approved by the Director of

the Federal Register as of February 27, 1995.

FOR FURTHER INFORMATION CONTACT: Garnett G. Adams, Chief, Outside Plant

Branch, Telecommunications Standards Division, Rural Utilities Service,

room 2844, South Building, U.S. Department of Agriculture, Washington,

DC 20250-1500, telephone (202) 720-0667.

SUPPLEMENTARY INFORMATION:

Executive Order 12866

This final rule has been determined to be not significant for the

purposes of Executive Order 12866 and therefore has not been reviewed

by the Office of Management and Budget.

Executive Order 12778

This final rule has been reviewed under Executive Order 12778,

Civil Justice Reform. If adopted, this final rule will not:

(1) Preempt any State or local laws, regulations, or policies;

(2) Have any retroactive effect; and

(3) Require administrative proceedings before parties may file suit

challenging the provisions of this rule.

Regulatory Flexibility Act Certification

The Administrator of RUS has determined that this final rule will

not have a significant economic impact on a substantial number of small

entities, as defined by the Regulatory Flexibility Act (5 U.S.C. 601 et

seq.). This final rule involves standards and specifications, which may

increase the direct short term costs to RUS borrowers. However, the

long-term direct economic costs are reduced through greater durability

and lower maintenance cost over time.

Information Collection and Recordkeeping Requirements

This final rule contains no information collection or recordkeeping

requirements under the Paperwork Reduction Act of 1980 (Pub. L. 96-

511).

National Environmental Policy Act Certification

The Administrator of RUS has determined that this final rule will

not significantly affect the quality of the human environment as

defined by the National Environmental Policy Act of 1969 (42 U.S.C.

4321 et seq.). Therefore, this action does not require an environmental

impact statement or assessment.

Catalog of Federal Domestic Assistance

The program described by this final rule is listed in the Catalog

of Federal Domestic Assistance programs under No. 10.851, Rural

Telephone Loans and Loan Guarantees, and No. 10.582, Rural Telephone

Bank Loans. This catalog is available on a subscription basis from the

Superintendent of Documents, the United States Government Printing

Office, Washington, DC 20402.

Executive Order 12372

This final rule is excluded from the scope of Executive Order

12372, Intergovernmental Consultation that requires intergovernmental

consultation with state and local officials. A Notice of Final Rule

titled Department Programs and Activities Excluded from Executive Order

12372 (50 FR 47034) exempts RUS and RTB loans and loan guarantees, and

RTB bank loans, to governmental and nongovernmental entities from

coverage under this Order.

Background

RUS issues publications titled ``Bulletin'' which serve to guide

borrowers regarding already codified policy, procedures, and

requirements needed to manage loans, loan guarantee programs, and the

security instruments which provide for and secure RUS financing. RUS

issues standards and specifications for the construction of telephone

facilities financed with RUS loan funds. RUS is rescinding Bulletin

345-6, RUS Standard for Splicing Plastic-Insulated Cables, PC-2, and

codifying the revised standard at 7 CFR 1755.200, RUS Standard for

Splicing Copper and Fiber Optic Cables.

RUS Bulletin 345-6 is used by borrowers and contractors as an

outside plant construction standard for splicing copper cables

installed in aerial and buried splice closures, ready-access

enclosures, and buried plant housings. Because of technological

advancements made in copper cable splicing methods and materials over

the past fifteen years, the current splicing methods and materials

relating to copper cables specified in the current standard have become

outdated. To allow borrowers and contractors to take advantage of these

improved methods and materials which will reduce installation costs,

the current standard will be revised to update the copper cable

splicing methods and materials to reflect these improved methods and

materials. [[Page 5097]]

The current standard does not include splicing methods and

materials used for fiber optic cables because at the time the standard

was written no such methods and materials were addressed because RUS

borrowers were providing telecommunication services to subscribers only

over copper cables. Since that time RUS borrowers have been providing

telecommunication services to subscribers over both copper and fiber

optic cables. Since RUS borrowers are installing fiber optic cables to

provide subscriber services, the current standard needs to be revised

to provide borrowers and contractors with standardized splicing methods

and materials for fiber optic cables.

This action will allow borrowers and contractors an economical and

efficient means of reducing their construction costs through the use of

improved splicing techniques for copper cables and standardized

splicing methods for fiber optic cables.

On August 29, 1994, RUS published a proposed rule (59 FR 44347) to

rescind RUS Bulletin 345-6, RUS Standard for Splicing Plastic-Insulated

Cables, PC-2, and to codify the revised standard at 7 CFR 1755.200, RUS

Standard for Splicing Copper and Fiber Optic Cables. Comments on this

proposed rule were due by October 28, 1994. No comments were received

by this due date.

Although no comments were received from any outside party on the

proposed rule, RUS, upon review of the proposed rule, discovered that

paragraph (e)(8) which makes reference to paragraphs (g)(4), (g)(5)(i),

(g)(5)(ii), and (g)(5)(iv) should be changed to reference paragraphs

(g)(4), and (g)(5)(i) through (g)(5)(iii) because paragraph (g)(5)(iv)

did not exist in the proposed rule. Therefore RUS will change the

paragraph (e)(8) to make reference to paragraphs (g)(4), and (g)(5)(i)

through (g)(5)(iii). This change will not result in any change in the

technical requirements of paragraph (e)(8).

List of Subjects in 7 CFR Part 1755

Incorporation by reference, Loan programs--communications, Rural

areas, Telephone.

For reasons set out in the preamble, RUS amends chapter XVII of

title 7 of the Code of Federal Regulations as follows:

PART 1755--TELECOMMUNICATIONS STANDARDS AND SPECIFICATIONS FOR

MATERIALS, EQUIPMENT AND CONSTRUCTION

1. The authority citation for part 1755 continues to read as

follows:

Authority: 7 U.S.C. 901 et seq., 1921 et seq.

Sec. 1755.97 [Amended]

2. Section 1755.97 is amended by removing the entry for RUS

Bulletin 345-6 from the table.

3. Section 1755.98 is amended by adding a new entry to the table in

numerical order to read as follows:

Sec. 1755.98 List of telephone standards and specifications included

in other 7 CFR parts.

* * * * *

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Section Issue date Title

------------------------------------------------------------------------

1755.200..... Jan. 26, 1995..... RUS Standard for Splicing Copper and

Fiber Optic Cables.

* * * * *

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4. Section 1755.200 is added to read as follows:

Sec. 1755.200 RUS standard for splicing copper and fiber optic cables.

(a) Scope. (1) This section describes approved methods for splicing

plastic insulated copper and fiber optic cables. Typical applications

of these methods include aerial, buried, and underground splices.

(2) American National Standard Institute/National Fire Protection

Association (ANSI/NFPA) 70, 1993 National Electrical Code (NEC)

referenced in this section is incorporated by reference by RUS. This

incorporation by reference was approved by the Director of the Federal

Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. A copy

of the ANSI/NFPA 1993 NEC standard is available for inspection during

normal business hours at RUS, room 2845, U.S. Department of

Agriculture, Washington, DC 20250-1500 or at the Office of the Federal

Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

Copies are available from NFPA, Batterymarch Park, Quincy,

Massachusetts 02269, telephone number 1 (800) 344-3555.

(3) American National Standard Institute/Institute of Electrical

and Electronics Engineers, Inc. (ANSI/IEEE), 1993 National Electrical

Safety Code (NESC) referenced in this section is incorporated by

reference by RUS. This incorporation by reference was approved by the

Director of the Federal Register in accordance with 5 U.S.C. 552(a) and

1 CFR part 51. A copy of the ANSI/IEEE 1993 NESC standard is available

for inspection during normal business hours at RUS, room 2845, U.S.

Department of Agriculture, Washington, DC 20250-1500 or at the Office

of the Federal Register, 800 North Capitol Street, NW., suite 700,

Washington, DC. Copies are available from IEEE Service Center, 455 Hoes

Lane, Piscataway, New Jersey 08854, telephone number 1 (800) 678-4333.

(b) General. (1) Only Rural Utilities Service (RUS) accepted filled

cable and splicing materials shall be used on outside plant projects

financed by RUS.

(2) The installation instructions provided by the manufacturer of

splicing materials shall be followed except where those instructions

conflict with the procedures specified in this section.

(3) Precautions shall be taken to prevent the ingress of moisture

and other contaminants during all phases of the splicing installation.

When an uncompleted splice must be left unattended, it shall be sealed

to prevent the ingress of moisture and other contaminants.

(4) Minor sheath damage during construction may be repaired if the

repair is completed immediately and approved by the borrower's resident

project representative. Minor damage is typically repaired by:

(i) Scuffing the cable sheath associated with the damaged area;

(ii) Applying several layers of DR tape over the scuffed and

damaged area;

(iii) Applying several layers of plastic tape over the DR tape; and

(iv) If damage is severe enough to rupture the cable shield, a

splice closure shall be installed.

(5) All splice cases installed on RUS toll trunk and feeder cables

shall be filled, whether aerial, buried, or underground.

(c) Splicing considerations for copper cables--(1) Preconstruction

testing. It is desirable that each reel of cable be tested for grounds,

opens, shorts, crosses, and shield continuity before the cable is

installed. However, manufacturer supplied test results are acceptable.

All cable pairs shall be free from electrical defects.

(2) Handling precautions. The cable manufacturer's instructions

concerning pulling tension and bending radius shall be observed. Unless

the cable manufacturer's recommendation is more stringent, the minimum

bending radius shall be 10 times the cable diameter for copper cables

and 20 times the cable diameter for fiber optic cables.

(3) Cable sheath removal. (i) The length of cable sheath to be

removed shall be governed by the type of splicing hardware used. Follow

the splice case manufacturer's recommendations. For pedestals or large

pair count splice housings, consider removing enough cable sheath to

allow the conductors to [[Page 5098]] extend to the top of the pedestal

and then to hang downward to approximately 15 centimeters (cm) (6

inches (in.)) above the baseplate.

(ii) Caution shall be exercised to avoid damaging the conductor

insulation when cutting through the cable shield and removing the

shield. Sharp edges and burrs shall be removed from the cut end of the

shield.

(4) Shield bonding and grounding. For personnel safety, the shields

of the cables to be spliced shall be bonded together and grounded

before splicing activities are started. (See paragraphs (g)(2), and

(g)(5)(i) through (g)(5)(iii) of this section for final bonding and

grounding provisions.)

(5) Binder group identification. (i) Color coded plastic tie wraps

shall be placed loosely around each binder group of cables before

splicing operations are attempted. The tie wraps shall be installed as

near the cable sheath as practicable and shall conform to the same

color designations as the binder ribbons. Twisted wire pigtails shall

not be used to identify binder groups due to potential transmission

degradation.

(ii) The standard insulation color code used to identify individual

cable pairs within 25-pair binder groups shall be as shown in Table 1:

Table 1.--Cable Pair Identification Within Binder Groups

------------------------------------------------------------------------

Color

Pair No. -------------------------

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 color code used to designate 25-

pair binder groups within 600-pair super units shall be as shown in

Table 2:

Table 2.--Cable Binder Group Identification

------------------------------------------------------------------------

Group pair

Group No. Color of bindings count

------------------------------------------------------------------------

1..................................... White-Blue.......... 1-25

2..................................... White-Orange........ 26-50

3..................................... White-Green......... 51-75

4..................................... White-Brown......... 76-100

5..................................... White-Slate......... 101-125

6..................................... Red-Blue............ 126-150

7..................................... Red-Orange.......... 151-175

8..................................... Red-Green........... 176-200

9..................................... Red-Brown........... 201-225

10.................................... Red-Slate........... 226-250

11.................................... Black-Blue.......... 251-275

12.................................... Black-Orange........ 276-300

13.................................... Black-Green......... 301-325

14.................................... Black-Brown......... 326-350

15.................................... Black-Slate......... 351-375

16.................................... Yellow-Blue......... 376-400

17.................................... Yellow-Orange....... 401-425

18.................................... Yellow-Green........ 426-450

19.................................... Yellow-Brown........ 451-475

20.................................... Yellow-Slate........ 476-500

21.................................... Violet-Blue......... 501-525

22.................................... Violet-Orange....... 526-550

23.................................... Violet-Green........ 551-575

24.................................... Violet-Brown........ 576-600

------------------------------------------------------------------------

(iv) Super-unit binder groups shall be identified in accordance

with Table 3:

Table 3.--Super-Unit Binder Colors

------------------------------------------------------------------------

Pair numbers Binder color

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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 cables shall be identified in

accordance with Table 4:

Table 4.--Screened Cable Service Pair Identification

------------------------------------------------------------------------

Color

Service pair No. -------------------------

Tip Ring

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1............................................. White....... Red.

2............................................. White....... Black.

3............................................. White....... Yellow.

4............................................. White....... Violet.

5............................................. Red......... Black.

6............................................. Red......... Yellow.

7............................................. Red......... Violet.

8............................................. Black....... Yellow.

9............................................. Black....... Violet.

------------------------------------------------------------------------

(6) Cleaning conductors. It is not necessary to remove the filling

compound from cable conductors before splicing. However, it is

permissible to wipe individual conductors with clean paper towels or

clean cloth rags. No cleaning chemicals, etc., shall be used. Caution

shall be exercised to maintain individual cable pair and binder group

identity. Binder group identity shall be maintained by using color

coded plastic tie wraps. Individual pair identification shall be

maintained by carefully twisting together the two conductors of each

pair.

(7) Expanded plastic insulated conductor (PIC) precautions. Solid

PIC and expanded (foam or foam skin) PIC are spliced in the same

manner, using the same tools and materials and, in general, should be

treated the same. However, the insulation on expanded PIC is much more

fragile than solid PIC. Twisting or forming expanded PIC into extremely

compact splice bundles and applying excessive amounts of tension when

tightening tie wraps causes shiners and, thus shall be avoided.

(8) Splice connectors. (i) Only RUS accepted filled splice

connectors shall be used on outside plant projects financed by RUS.

(ii) Specialized connectors are available for splicing operations

such as butt splices, in line splices, bridge taps, clearing and

capping, and multiple pair splicing operations. The splice connector

manufacturer's recommendations shall be followed concerning connector

selection and use.

(iii) Caution shall be exercised to maintain conductor and pair

association both during and after splicing operations.

(iv) Splicing operations that involve pairs containing working

services shall utilize splice connectors that permit splicing without

the interruption of service.

(9) Piecing out conductors. Conductors may be pieced-out to provide

additional slack or to repair damaged conductors. However, the

conductors shall be pieced-out with conductors having the same gauge

and type and color of insulation. The conductors used for piecing-out

shall be from cables having RUS acceptance.

(10) Splice organization. Spliced pair bundles shall be arranged in

firm lay-ups with minimum conductor tension in accordance with the

manufacturer's instructions.

(11) Binder tape. Perforated nonhygroscopic and nonwicking binder

tape should be applied to splices housed in filled splice cases. The

binder tape allows the flow of filling compound while holding the

splice bundles near the center of the splice case to allow adequate

coverage of filling compound. [[Page 5099]]

(12) Cable tags. Cables shall be identified by a tag indicating the

cable manufacturer's name, cable size, date of placement, and generic

route information. Information susceptible to changes caused by future

cable throws and rearrangements should not be included. Tags on load

coil stubs shall include the serial number of the coil case, the

manufacturer's name, and the inductance value.

(13) Screened cable. Screened PIC cable is spliced in the same

manner as nonscreened PIC cable. However, special considerations are

necessary due to differences in the cable design. The transmit and

receive bundles of the cable shall be separated and one of the bundles

shall be wrapped with shielding material in accordance with the cable

manufacturer's recommendations. When acceptable to the cable

manufacturer, it is permissible to use either the scrap screening tape

removed from the cable during the sheath opening process provided the

screening tape is edge coated or new pressure sensitive aluminum foil

tape over polyethylene tape.

(14) Service wire connections. (i) Buried service wires may be

spliced directly to cable conductors inside pedestals using the same

techniques required for branch cables. Buried service wires may also be

terminated on terminal blocks inside pedestals in areas where high

service order activity or fixed count cable administration policies

require terminal blocks. However, only RUS accepted terminal blocks

equipped with grease or gel filled terminations to provide moisture and

corrosion resistance shall be used.

(ii) Only filled terminal blocks having RUS acceptance shall be

used on aerial service wire connections.

(15) Copper cable testing. Copper cable testing shall be performed

in accordance with RUS Bulletin 345-63, ``RUS Standard for Acceptance

Tests and Measurements of Telephone Plant,'' PC-4, (Incorporated by

reference at Sec. 1755.97).

(16) Cable acceptance. Installed cable shall be tested and pass the

inventory and acceptance testing specified in the Telephone System

Construction Contract (Labor and Materials), RUS Form 515. The tests

and inspections shall be witnessed by the borrower's resident project

representative. All conductors shall be free from grounds, shorts,

crosses, splits, and opens.

(d) Splice arrangements for copper cables--(1) Service distribution

closures. (i) Ready access closures permit cable splicing activities

and the installation of filled terminal blocks for service wire

connections in the same closure. Ready access designs shall allow

service technicians direct access to the cable core as well as the

terminal block.

(ii) Fixed count terminals shall restrict service technician access

to the cable core. Predetermined cable pairs shall be spliced to the

terminal leads or stub cable in advance of service assignments.

(2) Aerial splices. Aerial splice cases accommodate straight

splices, branch splices, load coils, and service distribution

terminals. Aerial splicing arrangements having more than 4 cables

spliced in the same splice case are not recommended. Stub cabling to a

second splice case to avoid a congested splice is acceptable.

(3) Buried splices. (i) Direct buried splice cases accommodate

straight splices, branch splices, and load coils. Direct buried splices

shall be filled and shall be used only when above ground splicing in

pedestals is not practicable.

(ii) A treated plank or equivalent shall be placed 15 cm (6 in.)

above the buried splice case to prevent damage to the splice case from

future digging. Where a firm base for burying a splice cannot be

obtained, a treated plank or equivalent shall be placed beneath the

splice case.

(iii) Each buried splice shall be identified for future locating.

One method of marking the splice point is the use of a warning sign.

Another method is the burying of an electronic locating device.

(4) BD-type pedestals. (i) BD-type pedestals are housings primarily

intended to house, organize, and protect cable terminations

incorporating splice connectors, ground lugs, and load coils.

Activities typically performed in pedestals are cable splicing, shield

bonding and grounding, loading, and connection of subscriber service

drops.

(ii) The recommended splice capacities for BD-type pedestals are

shown in Table 5. However, larger size pedestals are permissible if

service requirements dictate their usefulness. Table 5 is as follows:

Table 5.--Splice Capacities for BD-Type Pedestals

------------------------------------------------------------------------

Maximum load

Maximum straight splice pair

splice maximum capacity

load splice pair using single

capacity using pair

Pedestal type single pair connectors or

connectors or multiple pair

multiple pair splice

splice modules 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 direct

buried with stub cables extending into the pedestal for splicing.

Requirements involving individual coil arrangements inside the

pedestal should be engineered on a case-by-case basis.

(iii) Special distribution pedestals having a divider plate for

mounting filled terminal blocks are available. Distribution pedestals

are also equipped with service wire channels for installation of buried

service wires without disturbing the cabling and gravel inside the base

of the pedestal. Distribution pedestals are recommended in locations

where the connection of service wires is required.

(5) Large pair count splice housings. Large pair count splice

housings are recommended for areas not suitable for man- holes. The

recommended capacities are shown in Table 6:

Table 6.--Splice Capacities for Large Count Housings

------------------------------------------------------------------------

Maximum load

Maximum straight splice pair

splice pair capacity capacity using

using single pair single pair

Housing type connectors or connectors or

multiple pair splice multiple pair

modules splice 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 to protect splices susceptible to unnecessary handling

where subsequent work activities are required or expected to occur

after splices have been completed. Restricted access inserts also

provide moisture protection in areas susceptible to temporary flooding.

A [[Page 5100]] typical restricted access insert is shown in Figure 1:

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[GRAPHIC][TIFF OMITTED]TR26JA95.002

BILLING CODE 3410-15-C [[Page 5101]]

(7) Serving Area Interface (SAI) Systems. SAI systems provide the

cross-connect point between feeder and distribution cables. Connection

of feeder to distribution pairs is accomplished by placing jumpers

between connecting blocks. Only RUS accepted connecting blocks having

grease or gel filled terminations to provide moisture and corrosion

resistance shall be used.

(8) Buried cable splicing arrangements. Typical buried cable

splicing arrangements are illustrated in Figures 2 through 5:

BILLING CODE 3410-15-P

[[Page 5102]]

[GRAPHIC][TIFF OMITTED]TR26JA95.003

[[Page 5103]]

[GRAPHIC][TIFF OMITTED]TR26JA95.004

[[Page 5104]]

[GRAPHIC][TIFF OMITTED]TR26JA95.005

[[Page 5105]]

[GRAPHIC][TIFF OMITTED]TR26JA95.006

BILLING CODE 3410-15-C

[[Page 5106]]

(9) Underground splices (manholes). Underground splice cases

accommodate straight splices, branch splices, and load coils.

Underground splices shall be filled.

(10) Central office tip cable splices. (i) Filled cable or filled

splices are not recommended for use inside central offices, except in

cable vault locations. Outside plant cable sheath and cable filling

compound are susceptible to fire and will support combustion. Fire,

smoke, and gases generated by these materials during burning are

detrimental to telephone switching equipment.

(ii) Tip cables should be spliced in a cable vault. However, as a

last resort, tip cables may be spliced inside a central office if flame

retardant splice cases or a noncombustible central office splice

housing is used to contain the splice.

(iii) Splices inside the central office shall be made as close as

practical to the point where the outside plant cables enter the

building. Except in cable vault locations, outside plant cables within

the central office shall be wrapped with fireproof tape or enclosed in

noncombustible conduit.

(e) Splicing considerations for fiber optic cables--(1) Connection

characteristics. Splicing efficiency between optical fibers is a

function of light loss across the fiber junctions measured in decibels

(dB). A loss of 0.2 dB in a splice corresponds to a light transmission

efficiency of approximately 95.5 percent.

(2) Fiber core alignment. Fiber splicing techniques shall be

conducted in such a manner that the cores of the fibers will be aligned

as perfectly as possible to allow maximum light transmission from one

fiber to the next. Without proper alignment, light will leave the fiber

core and travel through the fiber cladding. Light outside the fiber

core is not a usable light signal. Core misalignment is illustrated in

Figure 6:

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[GRAPHIC][TIFF OMITTED]TR26JA95.007

BILLING CODE 3410-15-C

[[Page 5107]]

(3) Splice loss. (i) Splice loss can also be caused by fiber

defects such as nonidentical core diameters, cores not in center of the

fiber, and noncircular cores. Such defects are depicted in Figure 7:

BILLING CODE 3410-15-P

[[Page 5108]]

[GRAPHIC][TIFF OMITTED]TR26JA95.008

BILLING CODE 3410-15-C

[[Page 5109]]

(ii) Undesirable splice losses are caused by poor splicing

techniques including splicing irregularities such as improper cleaves

and dirty splices. Typical cleave problems are illustrated in Figure 8:

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[GRAPHIC][TIFF OMITTED]TR26JA95.009

BILLING CODE 3410-15-C [[Page 5110]]

(4) Handling precautions. The following precautions shall be

observed:

(i) Avoid damaging the cable during handling operations prior to

splicing. Minor damage may change the transmission characteristics of

the fibers to the extent that the cable section will have to be

replaced;

(ii) The cable manufacturer's recommendations concerning pulling

tension shall be observed. The maximum pulling tension for most fiber

optic cable is 2669 newtons (600 pound-force);

(iii) The cable manufacturer's recommendations concerning bending

radius shall be observed. Unless the cable manufacturer's

recommendation is more stringent, the minimum bending radius for fiber

optic cable shall be 20 times the cable diameter;

(iv) The cable manufacturer's recommendations concerning buffer

tube bending radius shall be observed. Unless the cable manufacturer's

recommendation is more stringent, the minimum bending radius for buffer

tubes is usually between 38 millimeters (mm) (1.5 in.) and 76 mm (3.0

in.). The bending limitations on buffer tubes are intended to prevent

kinking. Buffer tube kinking may cause excessive optical loss or fiber

breakage; and

(v) Handle unprotected glass fibers carefully to avoid introducing

flaws such as scratched or broken fibers.

(5) Personnel safety. The following safety precautions shall be

observed:

(i) Safety glasses shall be worn when handling glass fibers;

(ii) Never view open-ended fibers with the naked eye or a

magnifying device. Improper viewing of a fiber end that is transmitting

light may cause irreparable eye damage; and

(iii) Dispose of bare scrap fibers by using the sticky side of a

piece of tape to pick up and discard loose fiber ends. Fiber scraps

easily penetrate the skin and are difficult to remove.

(6) Equipment requirements. (i) Fiber optic splices shall be made

in areas where temperature, humidity, and cleanliness can be

controlled. Both fusion and mechanical splicing techniques may require

a splicing vehicle equipped with a work station that will allow

environmental control.

(ii) Both fusion and mechanical splicing techniques are permitted

on RUS financed projects. When using the mechanical splicing technique,

only RUS accepted mechanical fiber optic splice connectors can be used.

(iii) Fusion splicing machines shall be kept in proper working

condition. Regular maintenance in accordance with the machine

manufacturer's recommendations shall be observed.

(iv) Mechanical splicing tools shall be in conformance with the

tool manufacturer's recommendations.

(v) An optical time domain reflectometer (OTDR) shall be used for

testing splices. The OTDR shall be stationed at the central office or

launch point for testing individual splices as they are made and for

end-to-end signature tests for the fiber optic link.

(vi) An optical power meter shall be used for end-to-end cable

acceptance tests.

(vii) A prerequisite for the successful completion of a fiber optic

splicing endeavor is the presence of a talk circuit between the

splicing technician in the splicing vehicle and the operator of the

OTDR in the central office. The splicing technician and the OTDR

operator shall have access to communications with each other in order

to inform each other as to:

(A) Which splices meet the loss objectives;

(B) The sequence in which buffer tubes and fibers are to be

selected for subsequent splicing operations; and

(C) The timing required for the performance of OTDR testing to

prevent making an OTDR test at the same time a splice is being fused.

(7) Cable preparation. (i) Engineering work prints shall prescribe

the cable slack needed at splice points to reach the work station

inside the splicing vehicle. Consideration should be given to the slack

required for future maintenance activity as well as initial

construction activities. The required slack may be different for each

splice point, depending on the site logistics. However, the required

slack is seldom less than 15 meters (50 feet). The amount of slack

actually used shall be recorded for each splice point to assist future

maintenance and restoration efforts.

(ii) The splice case manufacturer's recommendations concerning the

amount of cable sheath to be removed shall be followed to facilitate

splicing operations. The length of the sheath opening shall be

identified with a wrap of plastic tape.

(iii) If the cable contains a rip cord, the cable jacket shall be

ring cut approximately 15 cm (6 in.) from the end and the 15 cm (6 in.)

of cable jacket shall be removed to expose the rip cord. The rip cord

shall be used to slit the jacket to the tape mark.

(iv) If the cable does not contain a rip cord, the cable jacket

shall be slit using a sheath splitter. No cuts shall be made into the

cable core nor shall the buffer tubes be damaged.

(v) If the cable contains an armor sheath, the outer jacket shall

be opened along the slit and the jacket shall be removed exposing the

armor sheath. The armor shall be separated at the seam and pulled from

the cable exposing the inner jacket. The armor shall be removed making

allowances for a shield bond connector. The inner sheath shall be slit

using a sheath splitter or rip cord. The cable core shall not be

damaged nor shall there be any damage to the buffer tubes. The jacket

shall be peeled back and cut at the end of the slit. The exposed buffer

tubes shall not be cut, kinked, or bent.

(vi) After the cable sheath has been removed, the binder tape shall

be removed from the cable. The cable shall not be crushed or deformed.

(vii) The buffer tubes shall be unstranded one at a time. The

buffer tubes shall not be kinked.

(viii) If the cable is equipped with a strength member, the

strength member shall be cut to the length recommended by the splice

case manufacturer.

(ix) Each buffer tube shall be inspected for kinks, cuts, and flat

spots. If damage is detected, an additional length of cable jacket

shall be removed and all of the buffer tubes shall be cut off at the

point of damage.

(x) The cable preparation sequence shall be repeated for the other

cable end.

(8) Shield bonding and grounding. For personnel safety, the shields

and metallic strength members of the cables to be spliced shall be

bonded together and grounded before splicing activities are started.

(See paragraphs (g)(4), and (g)(5)(i) through (g)(5)(iii) of this

section for final bonding and grounding provisions).

(9) Fiber optic color code. The standard fiber optic color code for

buffer tubes and individual fibers shall be as shown in Table 7:

Table 7.--Fiber and Buffer Tube Identification

------------------------------------------------------------------------

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.

[[Page 5111]]

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 splice case manufacturer's

recommendation shall be followed concerning the total length of buffer

tube to be removed. Identify the length to be removed with plastic

tape.

(ii) Experiment with a scrap buffer tube to determine the cutting

tool adjustment required to ring cut a buffer tube without damaging the

fibers.

(iii) Buffer tubes shall be removed by carefully ring cutting and

removing approximately 15 to 46 cm (6 to 18 in.) of buffer tube at a

time. The process shall be repeated until the required length of buffer

tube has been removed, including the tape identification marker.

(11) Coated fiber cleaning. (i) Each coated fiber shall be cleaned.

The cable manufacturer's recommendations shall be followed concerning

the solvent required to clean the coated fibers. Reagent grade

isopropyl alcohol is a commonly used cleaning solvent.

(ii) A tissue or cotton ball shall be soaked in the recommended

cleaning solvent and the coated fibers shall be carefully wiped one at

a time using a clean tissue or cotton ball for each coated fiber.

Caution shall be exercised to avoid removing the coloring agent from

the fiber coating.

(12) Fiber coating removal. (i) Fiber coatings shall be removed. In

accordance with the splicing method used, the splice case

manufacturer's recommendation shall be followed concerning the length

of fiber coating to be removed.

(ii) The recommended length of fiber coating shall be removed only

on the two fibers to be spliced. Fiber coating removal shall be

performed on a one-fiber-at-a-time basis as each splice is prepared.

(13) Bare fiber cleaning. After the fiber coating has been removed,

the bare fibers shall be cleaned prior to splicing. Each fiber shall be

wiped with a clean tissue or cotton ball soaked with the cleaning

solvent recommended by the cable manufacturer. The bare fiber shall be

wiped one time to minimize fiber damage. Aggressive wiping of bare

fiber shall be avoided as it lowers the fiber tensile strength.

(14) Fiber cleaving. Cleaving tools shall be clean and have sharp

cutting edges to minimize fiber scratches and improper cleave angles.

Cleaving tools that are recommended by the manufacturer of the splicing

system shall be used.

(15) Cleaved fiber handling. The cleaved and cleaned fiber shall

not be allowed to touch other objects and shall be inserted into the

splicing device.

(16) Completion of the splice. (i) In accordance with the method of

splicing selected by the borrower, the splice shall be completed by

either fusing the splice or by applying the mechanical connector.

(ii) Each spliced fiber shall be routed through the organizer tray

one at a time as splices are completed. The fibers shall be organized

one at a time to prevent tangled spliced fibers. The splice case

manufacturer's recommendation shall be followed concerning the splice

tray selection.

(17) Fiber optic testing. Fiber optic testing shall be performed in

accordance with RUS Bulletin 345-63, ``RUS Standard for Acceptance

Tests and Measurements of Telephone Plant,'' PC-4, (Incorporated by

reference at Sec. 1755.97).

(18) Cable acceptance. Installed cable shall be tested and pass the

inventory and acceptance testing specified in the Telephone System

Construction Contract (Labor and Materials), RUS Form 515. The tests

and inspections shall be witnessed by the borrower's resident project

representative.

(f) Splice arrangements for fiber optic cables--(1) Aerial splices.

Cable slack at aerial splices shall be stored either on the messenger

strand, on the pole, or inside a pedestal at the base of the pole. A

typical arrangement for the storage of slack cable at aerial splices is

shown in Figure 9:

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(2) Buried splices. Buried splices shall be installed in handholes

to accommodate the splice case and the required splicing slack. An

alternative to the handhole is a pedestal specifically designed for

fiber optic splice cases. Typical arrangements for buried cable splices

are shown in Figures 10 and 11:

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(3) Underground manhole splices. Underground splices shall be

stored in manholes on cable hooks and racks fastened to the manhole

wall. The cable slack shall be stored on cable hooks and racks as shown

in Figure 12:

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(4) Central office cable entrance. (i) Filled cable or filled

splices are not recommended for use inside central offices except in

cable vault locations. Outside plant cable sheath and cable filling

compound are susceptible to fire and will support combustion. Fire,

smoke, and gases generated by these materials during burning are

detrimental to telephone switching equipment.

(ii) As a first choice, the outside plant fiber optic cable shall

be spliced to an all-dielectric fire retardant cable in a cable vault

with the all-dielectric cable extending into the central office and

terminating inside a fiber patch panel.

(iii) As a second choice, the outside plant cable may be spliced

inside the central office if a flame retardant fiber optic splice case

or a noncombustible central office splice housing equipped with

organizer trays is used to contain the splice.

(iv) In cases referenced in paragraphs (f)(4)(ii) and (f)(4)(iii)

of this section, as a minimum the fire retardant all-dielectric cable

used to provide the connection between the cable entrance splice and

the fiber patch panel shall be listed as Communication Riser Cable

(Type CMR) in accordance with Sections 800-50 and 800-51(b) of the 1993

National Electrical Code.

(v) Splices inside the central office shall be made as close as

practicable to the point where the outside plant cables enter the

building. Except in cable vault locations, outside plant cables within

the central office shall be wrapped with fireproof tape or enclosed in

noncombustible conduit.

(g) Bonding and grounding fiber optic cable, copper cable, and

copper service wire--(1) Bonding. Bonding is electrically connecting

two or more metallic items of telephone hardware to maintain a common

electrical potential. Bonding may involve connections to another

utility.

(2) Copper cable shield bond connections. (i) Cable shields shall

be bonded at each splice location. Only RUS accepted cable shield bond

connectors shall be used to provide bonding and grounding connections

to metallic cable shields. The shield bond connector manufacturer's

instructions shall be followed concerning installation and use.

(ii) (A) Shield bonding conductors shall be either stranded or

braided tinned copper wire equivalent to a minimum No. 6 American Wire

Gauge (AWG) and shall be RUS accepted. The conductor connections shall

be tinned or of a compatible bimetallic design to avoid corrosion

problems associated with dissimilar metals. The number of shield bond

connectors required per pair size and gauge shall be as shown in Table

8:

Table 8.--Shield Bond Connectors per Pair Size and Gauge

------------------------------------------------------------------------

Pair size and gauge

19 AWG ------------------------------------------ No. of shield

22 AWG 24 AWG 26 AWG bond connectors

------------------------------------------------------------------------

0-25........ 0-100 0-150 0-200 1

50-100...... 150-300 200-400 300-600 2

150-200..... 400-600 600-900 900-1500 3

300-600..... 900-1200 1200-2100 1800-3600 4

------------------------------------------------------------------------

(B) It is permissible to strap across the shield bond connectors of

several cables with a single length of braided wire. However, both ends

of the braid shall be terminated on the pedestal ground bracket to

provide a bonding loop. Shield bond connection methods for individual

cables are shown in Figures 13 through 15, and the bonding of several

cables inside a pedestal using the bonding loop is shown in Figure 16:

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(3) Buried service wire shield bond connections. Buried service

wire shields shall be connected to the pedestal bonding and grounding

system. Typical buried service wire installations are shown in Figures

17 and 18. In addition to the methods referenced in Figures 17 and 18,

the shields of buried service wires may also be connected to the

pedestal bonding and grounding system using buried service wire bonding

harnesses listed on Page 3.3.1, Item ``gs-b,'' of RUS Bulletin 1755I-

100. RUS Bulletin 1755I-100 may be purchased from the Superintendent of

Documents, U.S. Government Printing Office, Washington, DC 20402. When

those harnesses are used they shall be installed in accordance with the

manufacturer's instructions. Figures 17 and 18 are as follows:

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(4) Fiber optic cable bond connections. (i) The cable shield and

metallic strength members shall be bonded at each splice location. Only

RUS accepted fiber optic cable shield bond connectors shall be used to

provide bonding connections to the metallic cable shields. The shield

bond connector manufacturer's instructions shall be followed concerning

installation and use.

(ii) Shield bonding conductors shall be either stranded or braided

tinned copper wire equivalent to a minimum No. 6 American Wire Gauge

(AWG) and shall be RUS accepted. The conductor connections shall be

tinned or of a compatible bimetallic design to avoid corrosion problems

associated with dissimilar metals.

(5) Grounding. (i) Grounding is electrically connecting metallic

telephone hardware to a National Electrical Safety Code (NESC)

acceptable grounding electrode. Acceptable grounding electrodes are

defined in the Rule 99A of the NESC.

(ii) The conductor used for grounding metallic telephone hardware

shall be a minimum No. 6 AWG solid, bare, copper conductor.

(iii) For copper and fiber optic cable plant, all cable shields,

all metallic strength members, and all metallic hardware shall be:

(A) Grounded at each splice location to a driven grounding

electrode (ground rod) of:

(1) At least 1.5 meters (5 feet) in length where the local frost

level is normally less than 0.30 meters (1 foot) deep; or

(2) At least 2.44 meters (8 feet) in length where the local frost

level is normally 0.30 meters (1 foot) or deeper; and

(B) Bonded to a multi-grounded power system neutral when the splice

is within 1.8 meters (6 feet) of access to the grounding system of the

multi-grounded neutral system. Bonding to the multi-grounded neutral of

a parallel power line may help to minimize telephone interference on

long exposures with copper cable plant. Consideration, thus, should be

given to completing such bonds, at least four (4) times each mile, when

splices are greater than 1.8 meters (6 feet) but less than 4.6 meters

(15 feet) from access to the multi-grounded neutral.

(6) Bonding and grounding splice cases. (i) Splice cases are

equipped with bonding and grounding devices to ensure that cable

shields and metallic strength members maintain electrical continuity

during and after cable splicing operations. The splice case

manufacturer's recommendations shall be followed concerning the bonding

and grounding procedures. Conductors used for bonding shall be either

stranded or braided tinned copper wire equivalent to 6 AWG. Conductors

used for grounding shall be a solid, bare, copper wire equivalent to

minimum No. 6 AWG.

(ii) Buried splice cases installed in either handholes or pedestals

shall be grounded such that the cable shield grounds are attached to a

common ground connection that will allow the lifting of a ground on the

cable shield in either direction to permit efficient cable locating

procedures. As a first choice, buried grounding conductor(s) shall be

bare. However, if two or more grounding conductors are buried in the

same trench, they shall be insulated to avoid shorts when a locating

tone is applied.

(iii) A typical bonding and grounding method for fiber optic

splices is shown in Figure 19:

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(7) Bonding and grounding central office cable entrances. The RUS

Telecommunications Engineering and Construction Manual (TE&CM) Section

810 provides bonding and grounding guidance for central office cable

entrances. Splicing operations shall not be attempted before all

metallic cable shield and strength members are bonded and grounded.

Dated: January 18, 1995.

Bob J. Nash,

Under Secretary, Rural Economic and Community Development.

[FR Doc. 95-1937 Filed 1-25-95; 8:45 am]

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