[Federal Register Volume 60, Number 17 (Thursday, January 26, 1995)]
[Rules and Regulations]
[Pages 5096-5127]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-1937]
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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.
* * * * *
------------------------------------------------------------------------
Section Issue date Title
------------------------------------------------------------------------
1755.200..... Jan. 26, 1995..... RUS Standard for Splicing Copper and
Fiber Optic Cables.
* * * * *
------------------------------------------------------------------------
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
------------------------------------------------------------------------
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
------------------------------------------------------------------------
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:
BILLING CODE 3410-15-P
[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:
BILLING CODE 3410-15-P
[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:
BILLING CODE 3410-15-P
[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]
BILLING CODE 3410-15-P
