[Code of Federal Regulations]
[Title 7, Volume 11]
[Revised as of January 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 7CFR1755.860]
[Page 664-680]
TITLE 7--AGRICULTURE
CHAPTER XVII--RURAL UTILITIES SERVICE, DEPARTMENT OF AGRICULTURE
PART 1755--TELECOMMUNICATIONS STANDARDS AND SPECIFICATIONS FOR MATERIALS, EQUIPMENT AND CONSTRUCTION--Table of Contents
Sec. 1755.860 RUS specification for filled buried wires.
(a) Scope. (1) This section covers the requirements for filled
buried wires intended for direct burial as a subscriber drop and/or
distribution wire.
(i) The conductors are solid copper, individually insulated with an
extruded solid insulating compound.
(ii) The insulated conductors are twisted into pairs (a star-quad
configuration is permitted for the two pair wires) which are then
stranded or oscillated to form a cylindrical core.
[[Page 665]]
(iii) A moisture resistant filling compound is applied to the
stranded conductors completely covering the insulated conductors and
filling the interstices between the pairs.
(iv) The wire structure is completed by the application of an
optional core wrapping material, an inner jacket, a flooding compound, a
shield, a flooding compound, and an overall plastic jacket.
(2) The number of pairs and gauge size of conductors which are used
within the RUS program are provided in the following table:
------------------------------------------------------------------------
American Wire Gauge (AWG) 22................ 24
Pairs 2................. 2
3................. 3
------------------------------------------------------------------------
(3) All wires sold to RUS borrowers for projects involving RUS loan
funds under this section must be accepted by RUS Technical Standards
Committee ``A'' (Telephone). For wires manufactured to the specification
of this section, all design changes to an accepted design must be
submitted for acceptance. RUS will be the sole authority on what
constitutes a design change.
(4) Materials, manufacturing techniques, or wire designs not
specifically addressed by this section may be allowed if accepted by
RUS. Justification for acceptance of modified materials, manufacturing
techniques, or wire designs must be provided to substantiate product
utility and long term stability and endurance.
(5) The American National Standards Institute/Electronic Industries
Association (ANSI/EIA) 359-A-84, EIA Standard Colors for Color
Identification and Coding, 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. Copies of ANSI/EIA 359-A-84 are 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 EIA, 2001 Pennsylvania Avenue, NW., suite 900,
Washington, DC 20006, telephone number (202) 457-4966.
(6) American Society for Testing and Materials specifications (ASTM)
A 505-87, Standard Specification for Steel, Sheet and Strip, Alloy, Hot-
Rolled and Cold-Rolled, General Requirements for; ASTM B 3-90, Standard
Specification for Soft or Annealed Copper Wire; ASTM B 193-87, Standard
Test Method for Resistivity of Electrical Conductor Materials; ASTM B
224-91, Standard Classification of Coppers; ASTM B 694-86, Standard
Specification for Copper, Copper Alloy, and Copper-Clad Stainless Steel
Sheet and Strip for Electrical Cable Shielding; ASTM D 150-87, Standard
Test Methods for A-C Loss Characteristics and Permittivity (Dielectric
Constant) of Solid Electrical Insulating Materials; ASTM D 257-91,
Standard Test Methods for D-C Resistance or Conductance of Insulating
Materials; ASTM D 1238-90b, Standard Test Method for Flow Rates of
Thermoplastics by Extrusion Plastometer; ASTM D 1248-84(1989), Standard
Specification for Polyethylene Plastics Molding and Extrusion Materials;
ASTM D 1535-89, Standard Test Method for Specifying Color by the Munsell
System; ASTM D 3349-86, Standard Test Method for Absorption Coefficient
of Carbon Black Pigmented Ethylene Plastic; ASTM D 4101-82(1988),
Standard Specification for Propylene Plastic Injection and Extrusion
Materials; ASTM D 4565-90a, Standard Test Methods for Physical and
Environmental Performance Properties of Insulations and Jackets for
Telecommunications Wire and Cable; ASTM D 4566-90, Standard Test Methods
for Electrical Performance Properties of Insulations and Jackets for
Telecommunications Wire and Cable; ASTM D 4568-86, Standard Test Methods
for Evaluating Compatibility between Cable Filling and Flooding
Compounds and Polyolefin Cable Materials; ASTM D 4872-88, Standard Test
Method for Dielectric Testing of Wire and Cable Filling Compounds; ASTM
E 8-91, Standard Test Methods of Tension Testing of Metallic Materials;
and ASTM E 29-90, Standard Practice for Using Significant Digits in Test
Data to Determine Conformance with Specifications, referenced in this
section are incorporated by reference by RUS. These
[[Page 666]]
incorporations by references were approved by the Director of the
Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51.
Copies of the ASTM standards are available for inspection during normal
business hours at RUS, room 2845, U.S. Department 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 ASTM, 1916 Race Street, Philadelphia, Pennsylvania 19103-
1187, telephone number (215) 299-5585.
(b) Conductors and conductor insulation. (1) Each conductor must be
a solid round wire of commercially pure annealed copper. Conductors must
meet the requirements of the American Society for Testing and Materials
(ASTM) B 3-90 except that requirements for Dimensions and Permissible
Variations are waived and elongation requirements are superseded by this
section.
(2) The minimum conductor elongation in the final wire must comply
with the following limits when tested in accordance with ASTM E 8-91.
------------------------------------------------------------------------
Minimum
Conductor--AWG Elongation--
Percent
------------------------------------------------------------------------
22 20
24 16
------------------------------------------------------------------------
(3) Joints made in conductors during the manufacturing process may
be brazed, using a silver alloy solder and nonacid flux, or they may be
welded using either an electrical or cold welding technique. In joints
made in uninsulated conductors, the two conductor ends must be butted.
Splices made in insulated conductors need not be butted but may be
joined in a manner acceptable to RUS.
(4)(i) The tensile strength of any section of a conductor containing
a factory joint must not be less than 85 percent of the tensile strength
of an adjacent section of the solid conductor of equal length without a
joint.
(ii) Engineering Information: The sizes of wire used and their
nominal diameters shall be as shown in the following table:
------------------------------------------------------------------------
Nominal Diameter
AWG ------------------------------------
Millimeters (mm) (Inches (in.))
------------------------------------------------------------------------
22 0.643 (0.0253)
24 0.511 (0.0201)
------------------------------------------------------------------------
(5) Each conductor must be insulated with either a colored, solid,
insulating grade, high density polyethylene or crystalline propylene/
ethylene copolymer or with a solid natural primary layer and a colored,
solid outer skin using one of the insulating materials listed in
paragraphs (b)(5)(i) through (b)(5)(ii) of this section.
(i) The polyethylene raw material selected to meet the requirements
of this section must be Type III, Class A, Category 4 or 5, Grade E9, in
accordance with ASTM D 1248-84(1989).
(ii) The crystalline propylene/ethylene raw material selected to
meet the requirements of this section must be Class PP 200B 40003 E11 in
accordance with ASTM D 4101-82(1988).
(iii) Raw materials intended as conductor insulation furnished to
these requirements must be free from dirt, metallic particles, and other
foreign matter.
(iv) All insulating raw materials must be accepted by RUS prior to
their use.
(6) All conductors in any single length of wire must be insulated
with the same type of material.
(7) A permissible overall performance level of faults in conductor
insulation must average not greater than one fault per 12,000 conductor
meters (40,000 conductor feet) for each gauge of conductor.
(i) All insulated conductors must be continuously tested for
insulation faults during the twinning operation with the method of test
acceptable to RUS. The length count and number of faults must be
recorded. The information must be retained for a period of 6 months and
be available for review by RUS when requested.
(ii) The voltages for determining compliance with the requirements
of this section are as follows:
[[Page 667]]
------------------------------------------------------------------------
Direct Current Voltages
AWG (Kilovolts)
------------------------------------------------------------------------
22 6.0
24 5.0
------------------------------------------------------------------------
(8) Repairs to the conductor insulation during manufacturing are
permissible. The method of repair must be accepted by RUS prior to its
use. The repaired insulation must be capable of meeting the relevant
electrical requirements of this section.
(9) All repaired sections of insulation must be retested in the same
manner as originally tested for compliance with paragraph (b)(7) of this
section.
(10) Colored insulating material removed from or tested on the
conductor, from a finished wire, must be capable of meeting the
following performance requirements:
------------------------------------------------------------------------
Crystalline
Propylene/
Property Polyethylene Ethylene
Copolymer
------------------------------------------------------------------------
Melt Flow Rate
Percent increase from raw
material, Maximum.
<0.5 (Initial Melt Index)....... 50 --
0.5-2.00 (Initial Melt Index)... 25 --
[le]5.0 (Initial Melt Index).... -- 110
Tensile Strength--Minimum
Megapascals (MPa)............... 16.5 21.0
(Pounds per Square Inch (psi)).. (2,400) (3,000)
Ultimate Elongation
Minimum, Percent................ 300 300
Cold Bend
Failures, Maximum............... 0/10 0/10
Shrinkback
Maximum, mm (in.)............... 10 (0.375) 10 (0.375)
Oxygen Induction Time
Minimum, Minutes................ 20 20
------------------------------------------------------------------------
(11) Testing procedures. The procedures for testing the insulation
samples for compliance with paragraph (b)(10) of this section must be as
follows.
(i) Melt flow rate. The melt flow rate must be determined as
described in ASTM D 1238-90b. Condition E must be used for polyethylene.
Condition L must be used for crystalline propylene/ethylene copolymer.
The melt flow test must be conducted prior to the filling operation.
(ii) Tensile strength and ultimate elongation. Samples of the
insulation material, removed from the conductor, must be tested in
accordance with ASTM D 4565-90a using the following conditions. The
minimum length of unclamped specimen must be 50 mm (2.0 in.). The
minimum speed of jaw separation must be 25 mm (1.0 in.) per minute per
25 mm (1.0 in.) of unclamped specimen. The temperature of specimens and
surrounding shall be 23 1 deg.C.
Note: Quality assurance testing at a jaw separation speed of 500 mm/
min (20 in./min) is permissible. Failures at this rate must be retested
at the 50 mm/min (2 in./min) rate to determine section compliance.
(iii) Cold bend. Samples of the insulation material on the conductor
must be tested in accordance with ASTM D 4565-90a at a temperature of -
40 1 deg.C with a mandrel diameter equal to 3 times the
outside diameter of the insulated conductor. There must be no cracks
visible to normal or corrected-to-normal vision.
(iv) Shrinkback. Samples of insulation must be tested for four hours
in accordance with ASTM D 4565-90a. The temperature for the type of
material is listed as follows:
------------------------------------------------------------------------
Material Temperature
------------------------------------------------------------------------
Polyethylene 115 1 deg.C
Crystalline propylene/ethylene Copolymer 130 1 deg.C
------------------------------------------------------------------------
(v) Oxygen induction time. Samples of insulation, which have been
conditioned in accordance with paragraph 17.3 of ASTM D 4565-90a, must
be tested in accordance with the procedures of ASTM D 4565-90a using
copper pans and a test temperature of 199 1 deg.C.
(12) Other methods of testing may be used if acceptable to RUS.
(c) Identification of pairs and twisting of pairs. (1) The
insulation must be colored to identify:
[[Page 668]]
(i) The tip and ring conductor of each pair; and
(ii) Each pair in the completed wire.
(2) The colors to be used to provide identification of the tip and
ring conductor of each pair are shown in the following table:
------------------------------------------------------------------------
Color
Pair No. ---------------------------------
Tip Ring
------------------------------------------------------------------------
1 White Blue
2 White Orange
3 White Green
------------------------------------------------------------------------
(3) Standards of color. The colors of the insulated conductors
supplied in accordance with this section are specified in terms of the
Munsell Color System (ASTM D 1535-89) and must comply with the ``Table
of Wire and Cable Limit Chips'' as defined in ANSI/EIA-359-A-84. (Visual
color standards meeting these requirements may be obtained directly from
the Munsell Color Company, Inc., 2441 North Calvert Street, Baltimore,
Maryland 21218).
(4) Positive identification of the tip and ring conductors of each
pair by marking each conductor of a pair with the color of its mate is
permissible. The method of marking must be accepted by RUS prior to its
use.
(5) Other methods of providing positive identification of the tip
and ring conductors of each pair may be employed if accepted by RUS
prior to its use.
(6) The insulated conductors must be twisted into pairs.
(7) In order to provide sufficiently high crosstalk isolation, the
pair twists must be designed to enable the wire to meet the capacitance
unbalance and the crosstalk loss requirements of paragraphs (m)(2),
(m)(3), and (m)(4) of this section.
(8) The average length of pair twists in any pair in the finished
wire, when measured on any 3 meter (m) (10 foot(ft)) length, must not
exceed 152 mm (6 in.).
(9) An alternative method of forming the two pair wire is the use of
a star-quad configuration.
(i) The assembly of the star-quad must be such as to enable the wire
to meet the capacitance unbalance and the crosstalk loss requirements of
paragraphs (m)(2), (m)(3), and (m)(4) of this section.
(ii) The four individual insulated conductors must be twisted
together to form a star-quad configuration with the tip and ring
conductors of each pair diagonally opposite each other in the quad.
(iii) The average length of twist for the star-quad in the finished
wire, when measured on any 3 m (10 ft) length, must not exceed 152 mm (6
in.).
(iv) The following color scheme must be used to provide
identification of the tip and ring conductor of each pair in the star-
quad:
------------------------------------------------------------------------
Color
Pair No. ---------------------------------------
Tip Ring
------------------------------------------------------------------------
1 White with blue Blue
stripe.
2 White with orange Orange
stripe.
------------------------------------------------------------------------
(v) If desired, the blue and orange conductors may contain a white
stripe. The stripes in this case must be narrow enough so that the tip
and ring identification is obvious.
(d) Forming of the wire core. (1) Twisted pairs or star-quad
configuration must be assembled in such a way as to form a substantially
cylindrical group.
(2) The filling compound must be applied to the wire core in such a
way as to provide a completely filled core as is commercially practical.
(3) If desired for manufacturing reasons, white or colored binders
of nonhygroscopic and nonwicking material may be applied over the core.
(e) Filling compound. (1) After or during the stranding operation
and prior to application of the optional core wrap and inner jacket, a
homogeneous filling compound free of agglomerates must be applied to the
wire core. The compound must be as nearly colorless as is commercially
feasible and consistent with the end product requirements and pair
identification.
(2) The filling compound must be free from dirt, metallic particles,
and other foreign matter. It must be applied in such a way as to fill
the space within the wire core.
[[Page 669]]
(3) The filling compound must be nontoxic and present no dermal
hazards.
(4) The filling compound must exhibit the following dielectric
properties at a temperature of 23 3 deg.C when measured in
accordance with ASTM D 150-87 or ASTM D 4872-88.
(i) The dissipation factor must not exceed 0.0015 at a frequency of
1 megahertz (MHz).
(ii) The dielectric constant must not exceed 2.30.
(5) The volume resistivity must not be less than 10\12\ ohm-cm at a
temperature of 23 3 deg.C when measured in accordance with
ASTM D 257-91 or ASTM D 4872-88.
(6) The individual wire manufacturer must satisfy RUS that the
filling compound selected for use is suitable for its intended
application. The filling compound must be compatible with the wire
components when tested in accordance with ASTM D 4568-86 at a
temperature of 80 deg.C.
(f) Core wrap (optional). (1) When a core wrap is used, it must
consist of a layer of nonhygroscopic and nonwicking dielectric material.
The wrap must be applied with an overlap.
(2) The core wrap must provide a sufficient heat barrier to prevent
visible evidence of conductor insulation deformation or adhesion between
conductors, caused by adverse heat transfer during the inner jacketing
operation.
(3) If required for manufacturing reasons, white or colored binders
of nonhygroscopic and nonwicking material may be applied over the core
wrap.
(4) Sufficient filling compound must be applied to the core wrap
that voids or air spaces existing between the core and inner side of the
core wrap are minimized.
(g) Inner jacket. (1) An inner jacket must be applied over the core
and/or core wrap.
(2) The jacket must be free from holes, splits, blisters, or other
imperfections and must be as smooth and concentric as is consistent with
the best commercial practice.
(3) The inner jacket material and test requirements must be as
specified for the outer jacket material per paragraphs (j)(3) through
(j)(5)(iv) of this section.
(4) The inner jacket thickness at any point must not be less than
0.5 mm (0.020 in.). The thickness must be determined from measurements
on 50 mm (2 in.) samples taken not less than 0.3 m (1 ft) from either
end of the wire. The average must be determined from 4 readings taken
approximately 90 deg.apart on any cross section of the samples. The
maximum and minimum points must be determined by exploratory
measurements. The maximum thickness minus the minimum thickness at any
cross section must not exceed 43 percent of the average thickness at
that cross section.
(h) Flooding compound. (1) Sufficient flooding compound must be
applied on all sheath interfaces so that voids and air spaces in these
areas are minimized.
(2) The flooding compound must be compatible with the jacket when
tested in accordance with ASTM D 4568-86 at a temperature of 80 deg.C.
The floodant must exhibit adhesive properties sufficient to prevent
jacket slip when tested in accordance with the requirements of appendix
A, paragraph (III)(5), of this section.
(3) The individual wire manufacturer must satisfy RUS that the
flooding compound selected for use is acceptable for the application.
(i) Shield. (1) A shield must be applied either longitudinally or
helically over the inner jacket.
(i) If the shield is applied longitudinally, it must be corrugated.
(ii) If the shield is applied helically, it must be smooth.
(2) The overlap for longitudinally applied shields must be a minimum
of 2 mm (0.075 in.) The overlap for helically applied shields must be a
minimum of 23 percent of the tape width.
(3) General requirements for application of the shielding material
are as follows:
(i) Successive lengths of shielding tapes may be joined during the
manufacturing process by means of cold weld, electric weld, soldering
with a nonacid flux, or other acceptable means;
(ii) Where two ends of a metal shield are to be joined together,
care shall be taken to clean the metal surfaces in
[[Page 670]]
order to provide for a good mechanical and electrical connection;
(iii) The shields of each length of wire must be tested for
continuity. A one meter (3 ft) section of shield containing a factory
joint must exhibit not more than 110 percent of the resistance of a
shield of equal length without a joint;
(iv) The breaking strength of any section of a shield tape
containing a factory joint must not be less than 80 percent of the
breaking strength of an adjacent section of the shield of equal length
without a joint;
(v) The reduction in thickness of the shielding material due to the
corrugating or application process must be kept to a minimum and must
not exceed 10 percent at any spot; and
(vi) The shielding material must be applied in such a manner as to
enable the wire to pass the bend test as specified in paragraph (n)(3)
of this section.
(4) The following materials are acceptable for use as wire
shielding:
------------------------------------------------------------------------
Standard Wire Gopher Resistant Wire
------------------------------------------------------------------------
Copper Alloy 220 (Bronze)................. Copper-Clad Stainless Steel
(0.1016 0.0076 mm)............ 0.1270 0.0127 mm
(0.0040 0.0003 in.)........... (0.0050 0.0005
in.)
Copper Alloy 220 (Bronze)................. Copper Alloy 664
0.1270 0.0127 mm.............. 0.1397 0.0127 mm
(0.0050 0.0005 in.)........... (0.0055 0.0005
in.)
Copper-Clad Alloy Steel
0.1270 0.0127
(0.0050 0.0005
in.)
------------------------------------------------------------------------
(i) The copper-clad steels and copper alloy 664 shielding tapes must
be capable of meeting the following performance requirements prior to
application to the wire:
------------------------------------------------------------------------
Property Requirement
------------------------------------------------------------------------
Tensile Strength
Minimum, MPa (psi)...................... 379 (55,000)
Tensile Yield
Minimum, MPa (psi)...................... 241 (35,000)
Elongation
Minimum, percent in 50 mm (2 in.)....... 15
------------------------------------------------------------------------
(ii) Copper alloy 220. The shielding material, prior to application
to the wire, must be in the fully annealed condition and shall conform
to the requirements of ASTM B 694-86 for C22000 commercial bronze.
(iii) Copper-clad stainless steel. In addition to meeting the
requirements of paragraph (i)(4)(i) of this section, the shielding
material, prior to application to the wire, must be in the fully
annealed condition and must conform to the requirements of ASTM B 694-
86, with a cladding ratio of 16/68/16 and must have a minimum electrical
conductivity of 28 percent IACS when measured in accordance with ASTM B
193-87.
(iv) Copper alloy 664. In addition to meeting the requirements of
paragraph (i)(4)(i) of this section, the shielding material, prior to
application to the wire, must be annealed temper and must conform to the
requirements of ASTM B 694-86 and must have a minimum electrical
conductivity of 28 percent IACS when measured in accordance with ASTM B
193-87.
(v) Copper-clad alloy steel. In addition to meeting the requirements
of paragraph (i)(4)(i) of this section, the shielding material, prior to
application to the wire, must be in the fully annealed condition and the
copper component must conform to the requirements of ASTM B 224-91 and
the alloy steel component must conform to the requirements of ASTM A
505-87, with a cladding ratio of 16/68/16, and must have a minimum
electrical conductivity of 28 percent IACS when measured in accordance
with ASTM B 193-87.
(j) Outer jacket. (1) The outer jacket must provide the wire with a
tough, flexible, protective covering which can withstand exposure to
sunlight, to atmospheric temperatures and stresses reasonably expected
in normal installation and service.
(2) The jacket must be free from holes, splits, blisters, or other
imperfections and must be as smooth and concentric as is consistent with
the best commercial practice.
(3) The raw material used for the outer jacket must be one of the
five types listed in paragraphs (j)(3)(i) through (j)(3)(v) of this
section. The raw material must contain an antioxidant to provide long
term stabilization and the materials must contain a
[[Page 671]]
2.60 0.25 percent concentration of furnace black to provide
ultraviolet shielding. Both the antioxidant and furnace black must be
compounded into the material by the raw material supplier.
(i) Low density, high molecular weight polyethylene (LDHMW) must
conform to the requirements of ASTM D 1248-84(1989), Type I, Class C,
Category 4 or 5, Grade J3.
(ii) Low density, high molecular weight ethylene copolymer (LDHMW)
must conform to the requirements of ASTM D 1248-84 (1989), Type I, Class
C, Category 4 or 5, Grade J3.
(iii) Linear low density, high molecular weight polyethylene
(LLDHMW) must conform to the requirements of ASTM D 1248-84(1989), Type
I, Class C, Category 4 or 5, Grade J3.
(iv) High density polyethylene (HD) must conform to the requirements
of ASTM D 1248-84(1989), Type III, Class C, Category 4 or 5, Grade J4.
(v) Medium density polyethylene (MD) must conform to the
requirements of ASTM D 1248-84(1989), Type II, Class C, Category 4 or 5,
Grade J4.
(vi) Particle size of the carbon selected for use must not average
greater than 20 nanometers.
(vii) Absorption coefficient must be a minimum of 400 in accordance
with the procedures of ASTM D 3349-86.
(4) The outer jacketing material removed from or tested on the wire
must be capable of meeting the following performance requirements:
----------------------------------------------------------------------------------------------------------------
LLDHMW,
Property Ethylene LDHMW HD or MD
Copolymer Polyethylene Polyethylene
----------------------------------------------------------------------------------------------------------------
Melt Flow Rate Percent increase from raw material Maximum....... 50 50
<0.41 (Initial Melt Index)...................................... 100 -- --
0.41-2.00 (Initial Melt Index).................................. 50 -- --
Tensile Strength Minimum, MPa (psi)............................. 12.0 (1,700) 12.0 (1,700) 16.5 (2,400)
Ultimate Elongation Percent, Minimum............................ 400 400 300
Shrinkback Percent of Length, Maximum........................... 5 5 5
Impact Failures, Maximum........................................ 2/10 2/10 2/10
----------------------------------------------------------------------------------------------------------------
(5) Testing procedures. The procedures for testing the jacket
samples for compliance with paragraph (j)(4) of this section must be as
follows:
(i) Melt flow rate. The melt flow rate must be as determined by ASTM
D 1238-90b, Condition E. Jacketing material must be free from flooding
and filling compound.
(ii) Tensile strength and ultimate elongation. Test in accordance
with ASTM D 4565-90a, using a jaw separation speed of 500 mm/min (20
in./min) for low density material and 50 mm/min (2 in./min) for high and
medium density materials.
(iii) Shrinkback. Test in accordance with the procedures specified
in ASTM D 4565-90a using a test temperature of 100 1 deg.C
for low density material and a test temperature of 115 1
deg.C for high and medium density materials.
(iv) Impact. The test must be performed in accordance with ASTM D
4565-90a using an impact force of 4 newton-meter (3 pound force-foot) at
a temperature of -20 2 deg.C. The cylinder must strike the
sample at the shield overlap. A crack or split in the jacket constitutes
failure.
(6) Jacket thickness. The minimum jacket thickness must be 0.64 mm
(0.025 in.) except that the minimum thickness over the sheath slitting
cord, if present, must be 0.46 mm (0.018 in.). The minimum point must be
determined by exploratory measurements. The average thickness at any
cross section must be determined from four readings including the
minimum point, taken approximately 90 deg.apart. The thickness
measurement must exclude any jacket material that has formed into the
corrugation. The maximum thickness at any cross section must not be
greater than 155 percent of the minimum thickness.
(7) Eccentricity. The eccentricity of the jacket must not exceed 43
percent when calculated using the formula as follows:
[[Page 672]]
[GRAPHIC] [TIFF OMITTED] TC14NO91.092
(k) Sheath slitting cord (optional). (1) Sheath slitting cords may
be used in the wire structure at the option of the manufacturer.
(2) When a sheath slitting cord is used it must be nonhygroscopic
and nonwicking, continuous throughout a length of wire, and of
sufficient strength to open the sheath without breaking the cord.
(3) Sheath slitting cords must be capable of consistently slitting
the jacket(s) and/or shield for a continuous length of 0.6 m (2 ft) when
tested in accordance with the procedure specified in appendix B of this
section.
(l) Identification marker and length marker. (1) Each length of wire
must be permanently identified as to manufacturer and year of
manufacture.
(2) The number of conductor pairs and their gauge size must be
marked on the jacket.
(3) The marking must be printed on the jacket at regular intervals
of not more than 1.5 m (5 ft).
(4) An alternative method of marking may be used if accepted by RUS
prior to its use.
(5) The completed wire must have sequentially numbered length
markers in FEET OR METERS at regular intervals of not more than 1.5 m (5
ft) along the outside of the jacket.
(6) The method of length marking must be such that for any single
length of wire, continuous sequential numbering must be employed.
(7) The numbers must be dimensioned and spaced to produce good
legibility and must be approximately 3 mm (0.125 in.) in height. An
occasional illegible marking is permissible if there is a legible
marking located not more than 1.5 m (5 ft) from it.
(8) The method of marking must be by means of suitable surface
markings producing a clear, distinguishable, contrasting marking
acceptable to RUS. Where direct or transverse printing is employed, the
characters should be indented to produce greater durability of marking.
Any other method of length marking must be acceptable to RUS as
producing a marker suitable for the field. Size, shape and spacing of
numbers, durability, and overall legibility of the marker will be
considered in acceptance of the method.
(9) The accuracy of the length marking must be such that the actual
length of any wire section is never less than the length indicated by
the marking and never more than one percent greater than the length
indicated by the marking.
(10) The color of the initial marking must be white or silver. If
the initial marking fails to meet the requirements of the preceding
paragraphs, it will be permissible to either remove the defective
marking and re-mark with the white or silver color or leave the
defective marking on the wire and re-mark with yellow. No further re-
marking is permitted. Any re-marking must be on a different portion of
the wire circumference than any existing marking when possible and have
a numbering sequence differing from any other existing marking by at
least 5,000.
(11) Any reel of wire which contains more than one set of sequential
markings must be labeled to indicate the color and sequence of marking
to be used. The labeling must be applied to the reel and also to the
wire.
(m) Electrical requirements--(1) Mutual capacitance and conductance.
(i) The average mutual capacitance (corrected for length) of all pairs
in any reel must not exceed 52 4 nanofarad/ kilometer (nF/
km) (83 7 nanofarad/mile (nF/mile)) when tested in
accordance with ASTM D 4566-90 at a frequency of 1.0 0.1
kilohertz (kHz) and a temperature of 23 3 deg.C.
(ii) The mutual conductance (corrected for length and gauge) of any
pair must not exceed 2 micromhos/kilometer (micromhos/km) (3.3
micromhos/mile) when tested in accordance with ASTM D 4566-90 at a
frequency of 1.0 0.1 kHz and a temperature of 23
3 deg.C.
(2) Pair-to-pair capacitance unbalance. The capacitance unbalance
between any pair of the completed wire must not exceed 145 picofarad/
kilometer (pF/km) (80 picofarad/1000 ft (pF/1000 ft)) when tested in
accordance with ASTM D 4566-90 at a frequency of 1.0 0.1 kHz
and a temperature of 23 3 deg.C.
[[Page 673]]
(3) Pair-to-ground capacitance unbalance--(i) Pair-to-ground. The
capacitance unbalance as measured on the individual pairs of the
completed wire must not exceed 2625 pF/km (800 pF/1000 ft) when tested
in accordance with ASTM D 4566-90 at a frequency of 1.0 0.1
kHz and a temperature of 23 3 deg.C.
(ii) When measuring pair-to-ground capacitance unbalance, all pairs,
except the pair under test, are grounded to the shield.
(iii) Pair-to-ground capacitance unbalance may vary directly with
the length of the wire.
(4) Far-end crosstalk loss. (i) The output-to-outputfar-end
crosstalk loss (FEXT) between any pair combination of a completed wire
when measured in accordance with ASTM D 4566-90 at a test frequency of
150 kHz must not be less than 58 decibel/ kilometer (dB/km) (63 decibel/
1000 ft). If the loss Ko at a frequency Fo for
length Lo is known, then Kx can be determined for
any other frequency Fx or length Lx by:
[GRAPHIC] [TIFF OMITTED] TR19NO93.004
(5) Attenuation. The attenuation of any individual pair on any reel
of wire must not exceed the following limits when measured at or
corrected to a temperature of 20 1 deg.C and a test
frequency of 150 kHz. The test must be conducted in accordance with ASTM
D 4566-90.
------------------------------------------------------------------------
Individual Pair Attenuation dB/km
(decibel/mile (dB/mile))
Conductor AWG -----------------------------------
Maximum Minimum
------------------------------------------------------------------------
22 6.8 (11.0) 5.0 (8.1)
24 8.7 (14.0) 6.6 (10.7)
------------------------------------------------------------------------
(6) Insulation resistance. Each insulated conductor in each length
of completed wire, when measured with all other insulated conductors and
the shield grounded, must have an insulation resistance of not less than
1600 megohm-kilometer (1000 megohm-mile) at 20 1 deg.C. The
measurement must be made in accordance with the procedures of ASTM D
4566-90.
(7) High voltage test. (i) In each length of completed wire, the
insulation between conductors when tested in accordance with ASTM D
4566-90 must withstand for 3 seconds a direct current (dc) potential
whose value is not less than:
(A) 5.0 kilovolts for 22-gauge conductors; and
(B) 4.0 kilovolts for 24-gauge conductors.
(ii) In each length of completed wire, the dielectric strength
between the shield and all conductors in the core must be tested in
accordance with ASTM D 4566-90 and must withstand, for 3 seconds, a dc
potential whose value is not less than 20 kilovolts.
(8) Conductor resistance. The dc resistance of any conductor must be
measured in the completed wire in accordance with ASTM D 4566-90 and
must not exceed the following values when measured at or corrected to a
temperature of 20 1 deg.C.
------------------------------------------------------------------------
Maximum Resistance
AWG ----------------------------------
ohms/kilometer (ohms/1000 ft)
------------------------------------------------------------------------
22 57.1 (17.4)
24 90.2 (27.5)
------------------------------------------------------------------------
(9) Resistance unbalance. (i) The difference in dc resistance
between the two conductors of any pair in the completed wire must not
exceed 5.0 percent when measured in accordance with the procedures of
ASTM D 4566-90.
(ii) The resistance unbalance between tip and ring conductors shall
be random with respect to the direction of unbalance. That is, the
resistance of the tip conductors shall not be consistently higher with
respect to the ring conductors and vice versa.
(n) Mechanical requirements--(1) Defective wire. Pairs in each
length of wire will not be permitted to have either a ground, cross,
short or open circuit condition.
(2) Wire breaking strength. The breaking strength of the completed
wire must not be less than 890 newtons (200 pound-force) when tested in
accordance with ASTM D 4565-90a using a jaw separation speed of 25 mm/
min (1.0 in./min).
(3) Wire bending test. The completed wire must be capable of meeting
the requirements of ASTM D 4565-90a after
[[Page 674]]
conditioning at -20 2 deg.C and at 23 2 deg.C.
(4) Water penetration test. (i) A one meter (3 ft) length of
completed wire must be stabilized at 23 2 deg.C and tested
in accordance with ASTM D 4565-90a using a one meter (3 ft) water head
over the sample or placed under the equivalent continuous pressure for
one hour.
(ii) After the one hour period, there must be no water leakage in
the sheath interfaces, under the core wrap or between any insulated
conductors in the core.
(iii) If water leakage is detected in the first sample, one 3 m (10
ft) additional adjacent sample from the same reel of wire must be tested
in accordance with paragraph (n)(4)(ii) of this section. If the second
sample exhibits water leakage, the entire reel of wire is to be
rejected. If the second sample exhibits no leakage, the entire reel of
wire is considered acceptable.
(5) Compound flow test. The completed wire must be capable of
meeting the compound flow test specified in ASTM D 4565-90a when exposed
for a period of 24 hours at a temperature of 80 1 deg.C. At
the end of this test period, there must be no evidence of flowing or
dripping of compound from either the core or sheath interfaces.
(o) Acceptance testing and extent of testing. (1) The tests
described in appendix A of this section are intended for acceptance of
wire designs and major modifications of accepted designs. RUS decides
what constitutes a major modification. These tests are intended to show
the inherent capability of the manufacturer to produce wire products
having long life and stability.
(2) For initial acceptance, the manufacturer must submit:
(i) An original signature certification that the product fully
complies with each requirement of this section;
(ii) Qualification Test Data, per appendix A of this section;
(iii) To periodic plant inspections;
(iv) A certification that the product does or does not comply with
the domestic origin manufacturing provisions of the ``Buy American''
requirements of the Rural Electrification Act of 1938 (7 U.S.C. 901 et
seq.);
(v) Written user testimonials concerning performance of the product;
and
(vi) Other nonproprietary data deemed necessary by the Chief,
Outside Plant Branch (Telephone).
(3) For requalification acceptance, the manufacturer must submit an
original signature certification that the product fully complies with
each section of the specification, excluding the Qualification Section,
and a certification that the product does or does not comply with the
domestic origin manufacturing provisions of the ``Buy American''
requirements of the Rural Electrification Act of 1938 (7 U.S.C. 901 et
seq.) for acceptance by June 30 every three years. The required data and
certification must have been gathered within 90 days of the submission.
(4) Initial and requalification acceptance requests should be
addressed to: Chairman, Technical Standards, Committee ``A''
(Telephone), Telecommunications Standards Division, Rural Utilities
Service, Washington, DC 20250-1500.
(5) Tests on 100 percent of completed wire. (i) The shield of each
length of wire must be tested for continuity using the procedures of
ASTM D 4566-90.
(ii) Dielectric strength between all conductors and the shield must
be tested to determine freedom from grounds in accordance with paragraph
(m)(7)(ii) of this section.
(iii) Each conductor in the completed wire must be tested for
continuity using the procedures of ASTM D 4566-90.
(iv) Dielectric strength between conductors must be tested to ensure
freedom from shorts and crosses in accordance with paragraph (m)(7)(i)
of this section.
(v) The average mutual capacitance must be measured on all wires.
(6) Capability tests. Tests on a quality assurance basis must be
made as frequently as is required for each manufacturer to determine and
maintain compliance with:
(i) Performance requirements for conductor insulation and jacket
material;
(ii) Performance requirements for filling and flooding compounds;
[[Page 675]]
(iii) Sequential marking and lettering;
(iv) Capacitance unbalance and crosstalk;
(v) Insulation resistance;
(vi) Conductor resistance and resistance unbalance;
(vii) Wire bending and wire breaking strength tests;
(viii) Mutual conductance and attenuation; and
(ix) Water penetration and compound flow tests.
(p) Summary of records of electrical and physical tests. (1) Each
manufacturer must maintain suitable summary of records for a period of
at least 3 years for all electrical and physical tests required on
completed wire by this section as set forth in paragraphs (o)(5) and
(o)(6) of this section. The test data for a particular reel shall be in
a form that it may be readily available to the purchaser or to RUS upon
request.
(2) Measurements and computed values must be rounded off to the
number of places of figures specified for the requirement according to
ASTM E 29-90.
(q) Manufacturing irregularities. (1) Repairs to the inner jacket
and shield are not permitted in wire supplied to the end user under this
section.
(2) Minor defects in the outer jackets (defects having a dimension
of 3 mm (0.125 in.) or less in any direction) may be repaired by means
of heat fusing in accordance with good commercial practices utilizing
sheath grade compound.
(r) Preparation for shipment. (1) The wire must be shipped on reels.
The diameter of the drum must be large enough to prevent damage to the
wire from reeling or unreeling. The reels must be substantial and so
constructed as to prevent damage to the wire during shipment and
handling.
(2) The thermal wrap must comply with the requirements of appendix C
of this section. When a thermal reel wrap is supplied, the wrap must be
applied to the reel and must be suitably secured in place to minimize
thermal exposure to the wire during storage and shipment. The use of the
thermal reel wrap as a means of reel protection will be at the option of
the manufacturer unless specified by the end user.
(3) The outer end of the wire must be securely fastened to the reel
head so as to prevent the wire from becoming loose in transit. The inner
end of the wire must be securely fastened in such a way as to make it
readily available if required for electrical testing. Spikes, staples,
or other fastening devices which penetrate the wire jacket must not be
used. The method of fastening the wire ends must be accepted by RUS
prior to it being used.
(4) Each length of wire must be wound on a separate reel unless
otherwise specified or agreed to by the purchaser.
(5) Each reel must be plainly marked to indicate the direction in
which it should be rolled to prevent loosening of the wire on the reel.
(6) Each reel must be stenciled or labeled on either one or both
sides with the name of the manufacturer, year of manufacture, actual
shipping length, an inner and outer end sequential length marking,
description of the wire, reel number and the RUS wire designation:
Wire Designation
BFW
Wire Construction
Pair Count
Conductor Gauge
N = Copper Alloy 220 (Bronze) Shield
Y = Gopher Resistant Shields
Example: BFWY 3-24
Buried Filled Wire, Gopher Resistant Shield, 3 pair, 24 AWG
(7) Both ends of the filled buried wire, manufactured to the
requirements of this section, must be equipped with end caps which are
acceptable to RUS.
(The information and recordkeeping requirements of this section have
been approved by the Office of Management and Budget (OMB) under the
control number 0572-0059)
Appendix A to Sec. 1755.860--Qualification Test Methods
(I) The test procedures described in this appendix are for
qualification of initial designs and major modifications of accepted
designs. Included in (V) of this appendix are suggested formats that may
be used in submitting test results to RUS.
(II) Sample Selection and Preparation. (1) All testing must be
performed on lengths removed sequentially from the same 3 pair, 22 gauge
jacketed wire. This wire must not have been exposed to temperatures in
excess of 38 deg.C since its initial cool down after
[[Page 676]]
sheathing. The lengths specified are minimum lengths and if desirable
from a laboratory testing standpoint longer lengths may be used.
(a) Length A shall be 10 0.2 meters (33 0.5
feet) long and must be maintained at 23 3 deg.C. One length
is required.
(b) Length B shall be 12 0.2 meters (40 0.5
feet) long. Prepare the test sample by removing the inner and outer
jacket, shield, and core wrap, if present, for a sufficient distance on
both ends to allow the insulated conductors to be flared out. Remove
sufficient conductor insulation so that appropriate electrical test
connections can be made at both ends. Coil the specimen with a diameter
of 15 to 20 times its sheath diameter. Three lengths are required.
(c) Length C shall be one meter (3 feet) long. Four lengths are
required.
(d) Length D shall be 300 millimeters (1 foot) long. Four lengths
are required.
(e) Length E shall be 600 millimeters (2 feet) long. Four lengths
are required.
(f) Length F shall be 3 meters (10 feet) long and must be maintained
at 23 3 deg.C for the duration of the test. Two lengths are
required.
(2) Data Reference Temperature. Unless otherwise specified, all
measurements shall be made at 23 3 deg.C.
(III) Environmental Tests--(1) Heat Aging Test--(a) Test Samples.
Place one sample each of lengths B, C, D, and E in an oven or
environmental chamber. The ends of sample B must exit from the chamber
or oven for electrical tests. Securely seal the oven exit holes.
(b) Sequence of Tests. After conditioning the samples are to be
subjected to the following tests:
(i) Water Immersion Test outlined in (III)(2) of this appendix;
(ii) Water Penetration Test outlined in (III)(3) of this appendix; .
(iii) Insulation Compression Test outlined in (III)(4) of this
appendix; and
(iv) Jacket Slip Strength Test outlined in (III)(5) of this
appendix.
(c) Initial Measurements. (i) For sample B, measure the open circuit
capacitance and conductance for each pair at 1 and 150 kilohertz and the
attenuation at 150 kilohertz after conditioning the sample at the data
reference temperature for 24 hours. Calculate the average and standard
deviation for the data of the 3 pairs on a per kilometer (per mile)
basis.
(ii) The attenuation at 150 kilohertz may be calculated from open
circuit admittance (Yoc) and short circuit impedance (Zsc) or may be
obtained by direct measurement of attenuation.
(iii) Record on suggested formats attached in (V) of this appendix
or on other easily readable formats.
(d) Heat Conditioning. (i) Immediately after completing the initial
measurements, condition the sample for 14 days at a temperature of 65
2 deg.C.
(ii) At the end of this period note any exudation of filling
compound. Measure and calculate the parameters given in (III)(1)(c) of
this appendix. Record on suggested formats attached in (V) of this
appendix or on other easily readable formats.
(iii) Cut away and discard a one meter (3 foot) section from each
end of length B.
(e) Overall Electrical Deviation. (i) Calculate the percent change
in all average parameters between the final parameters after
conditioning with the initial parameters in (III)(1)(c) of this
appendix.
(ii) The stability of the electrical parameters after completion of
this test must be within the following prescribed limits:
(A) Capacitance. The average mutual capacitance must be within 5
percent of its original value;
(B) The change in average mutual capacitance must be less than 5
percent over the frequency range of 1 to 150 kilohertz;
(C) Conductance. The average mutual conductance must not exceed 2
micromhos/kilometer (3.3 micromhos/mile) at a frequency of 1 kilohertz;
and
(D) Attenuation. The attenuation must not have increased by more
than 5 percent over its original value.
(2) Water Immersion Electrical Test--(a) Test Sample Selection. The
10 meter (33 foot) section of length B must be tested.
(b) Test Sample Preparation. Prepare the sample by removing the
inner and outer jacket, shield, and core wrap, if present, for a
sufficient distance to allow one end to be accessed for test
connections. Cut out a series of 2.5 millimeter by 13 millimeter (0.1
inch by 0.5 inch) rectangular slots along the test sample, at 300
millimeter (1 foot) intervals progressing successively 90 degrees around
the circumference of the wire. Assure that the wire core is exposed at
each slot by slitting the inner jacket and core wrap if present. Place
the prepared sample in a dry vessel which when filled will maintain a
one meter (3 foot) head of water over 6 meters (20 feet) of uncoiled
wire. Extend and fasten the ends of the wire so they will be above the
water line and the pairs are rigidly held for the duration of the test.
(c) Capacitance and Conductance Testing. Measure the initial values
of mutual capacitance and conductance of all pairs in each wire at a
frequency of 1 kilohertz before filling the vessel with water. Be sure
the wire shield is grounded to the test equipment. Fill the vessel until
there is a one meter (3 foot) head of water on the wires.
(i) Remeasure the mutual capacitance and conductance after the wires
have been submerged for 24 hours and again after 30 days.
[[Page 677]]
(ii) Record each sample separately on the suggested formats attached
in (V) of this appendix or on other easily readable formats.
(d) Overall Electrical Deviation. (i) Calculate the percent change
in all average parameters between the final parameters after
conditioning with the initial parameters in (III)(2)(c) of this
appendix.
(ii) The stability of the electrical parameters after of the test
must be within the following prescribed limits:
(A) Capacitance. The average mutual capacitance must be within 5
percent of its original value; and
(B) Conductance. The average mutual conductance must not exceed 2
micromhos/kilometer (3.3 micromhos/mile) at a frequency of 1 kilohertz.
(3) Water Penetration Testing. (a) A watertight closure must be
placed over the jacket of length C. The closure must not be placed over
the jacket so tightly that the flow of water through preexisting voids
or air spaces is restricted. The other end of the sample must remain
open.
(b) Test per Option A or Option B. (i) Option A. Weigh the sample
and closure prior to testing. Fill the closure with water and place
under a continuous pressure of 10 0.7 kilopascals (1.5
0.1 pounds per square inch gauge) for one hour. Collect the
water leakage from the end of the test sample during the test and weigh
to the nearest 0.1 gram. Immediately after the one hour test, seal the
ends of the wire with a thin layer of grease and remove all visible
water from the closure, being careful not to remove water that
penetrated into the core during the test. Reweigh the sample and
determine the weight of water that penetrated into the core. The weight
of water that penetrated into the core must not exceed 1 gram.
(ii) Option B. Fill the closure with a 0.2 gram sodium fluorscein
per liter water solution and apply a continuous pressure of 10
0.7 kilopascals (1.5 0.1 pounds per square inch
gauge) for one hour. Catch and weigh any water that leaks from the end
of the wire during the one hour period. If no water leaks from the
sample, carefully remove the water from the closure. Then carefully
remove the outer jacket, shield, inner jacket and core wrap, if present,
one at a time, examining with an ultraviolet light source for water
penetration. After removal of the inner jacket and core wrap, if
present, carefully dissect the core and examine for water penetration
within the core. Where water penetration is observed, measure the
penetration distance. The distance of water penetration into the core
must not exceed 127 millimeters (5.0 inches).
(4) Insulation Compression Test. (a) Test Sample D. Remove inner and
outer jacket, shield, and core wrap, if present, being careful not to
damage the conductor insulation. Remove one pair from the core and
carefully separate, wipe off core filler and straighten the insulated
conductors. Retwist the two insulated conductors together under
sufficient tension to form 10 evenly spaced 360 degree twists in a
length of 100 millimeters (4 inches).
(b) Sample Testing. Center the mid 50 millimeters (2 inches) of the
twisted pair between two smooth rigid parallel metal plates measuring 50
millimeters (2 inches) in length or diameter. Apply a 1.5 volt direct
current potential between the conductors, using a light or buzzer to
indicate electrical contact between the conductors. Apply a constant
load of 67 newtons (15 pound-force) on the sample for one minute and
monitor for evidence of contact between the conductors. Record results
on suggested formats attached in (V) of this appendix or on other easily
readable formats.
(5) Jacket Slip Strength Test--(a) Sample Selection. Test sample E
from (III)(1)(a) of this appendix.
(b) Sample Preparation. Prepare test sample in accordance with the
procedures specified in ASTM D 4565-90a.
(c) Sample Conditioning and Testing. Remove the sample from the
tensile tester prior to testing and condition for one hour at 50
2 deg.C. Test immediately in accordance with the procedure
specified in ASTM D 4565-90a. A minimum outer jacket slip strength of 67
newtons (15 pound-force) is required. Record the load attained.
(6) Humidity Exposure. (a) Repeat steps (III)(1)(a) through
(III)(1)(c)(iii) of this appendix for separate set of samples B, C, D
and E which have not been subjected to prior environmental conditioning.
(b) Immediately after completing the measurements, expose the test
sample to 100 temperature cyclings. Relative humidity within the chamber
must be maintained at 90 2 percent. One cycle consists of
beginning at a stabilized chamber and test sample temperature of 52
1 deg.C, increasing the temperature to 57 1
deg.C, allowing the chamber and test samples to stabilize at this level,
then dropping the temperature back to 52 1 deg.C.
(c) Repeat steps (III)(1)(d)(ii) through (III)(5)(c) of this
appendix.
(7) Temperature Cycling. (a) Repeat steps (III)(1)(a) through
(III)(1)(c)(iii) of this appendix for separate set of samples B, C, D
and E which have not been subjected to prior environmental conditioning.
(b) Immediately after completing the measurements, subject the test
sample to 10 cycles of temperature between -40 deg.C and +60 deg.C.
The test sample must be held at each temperature extreme for a minimum
of 1 1/2 hours during each cycle of temperature. The air within the
temperature cycling chamber must be circulated throughout the duration
of the cycling.
(c) Repeat steps (III)(1)(d)(ii) through (III)(5)(c) of this
appendix.
[[Page 678]]
(IV) Control Sample--(1) Test Samples. A separate set of lengths for
samples A, C, D, and E must have been maintained at 23 3
deg.C for at least 48 hours before the testing.
(2) Repeat steps (III)(2) through (III)(5)(c) of this appendix
except use length A instead of length B.
(3) Surge Test. (a) One length of sample F must be used to measure
the breakdown between conductors while the other length of F must be
used to measure core to shield breakdown.
(b) The samples must be capable of withstanding, without damage, a
single surge voltage of 20 kilovolts peak between conductors, and 35
kilovolts peak between conductors and the shield as hereinafter
described. The surge voltage must be developed from a capacitor
discharge through a forming resistor connected in parallel with the
dielectric of the test sample. The surge generator constants must be
such as to produce a surge of 1.5 x 40 microseconds wave shape.
(c) The shape of the generated wave must be determined at a reduced
voltage by connecting an oscilloscope across the forming resistor with
the wire sample connected in parallel with the forming resistor. The
capacitor bank is charged to the test voltage and then discharged
through the forming resistor and test sample. The test sample will be
considered to have passed the test if there is no distinct change in the
wave shape obtained with the initial reduced voltage compared to that
obtained after the application of the test voltage.
(V) The following suggested formats may be used in submitting the
test results to RUS:
Environmental Conditioning --------------
FREQUENCY 1 kilohertz
----------------------------------------------------------------------------------------------------------------
CAPACITANCE CONDUCTANCE
----------------------------------------------------------------------------
PAIR NUMBER nF/km (nF/mile) micromhos/km (micromhos/mile)
----------------------------------------------------------------------------
Initial Final Initial Final
----------------------------------------------------------------------------------------------------------------
1 -------- -------- -------- --------
2 -------- -------- -------- --------
3 -------- -------- -------- --------
Average x -------- -------- -------- --------
----------------------------------------------------------------------------------------------------------------
Overall Percent Difference in Average x Capacitance:---------------------------- Conductance:
----------------------------
Environmental Conditioning ------------------------
FREQUENCY 150 kilohertz
----------------------------------------------------------------------------------------------------------------
CAPACITANCE CONDUCTANCE ATTENUATION
--------------------------------------------------------------------------------
nF/km (nF/mile) micromhos/km (micromhos/ dB/km (dB/mile)
PAIR NUMBER ----------------------------------------- mile) -----------------------
----------------
Initial Final Initial Final Initial Final
----------------------------------------------------------------------------------------------------------------
1 ------ ------ ------ ------ ------ ------
2 ------ ------ ------ ------ ------ ------
3 ------ ------ ------ ------ ------ ------
Average x ------ ------ ------ ------ ------ ------
----------------------------------------------------------------------------------------------------------------
Overall Percent Difference in Average x Capacitance:---------------------- Conductance: --------------
-------- Attenuation:----------------------
[[Page 679]]
Environmental Conditioning ------------------------------
WATER IMMERSION TEST (1 kilohertz)
----------------------------------------------------------------------------------------------------------------
CAPACITANCE CONDUCTANCE
-------------------------------------------------------------------------------
PAIR NUMBER nF/km (nF/mile) micromhos/km (micromhos/mile)
-------------------------------------------------------------------------------
Initial 24 hours Final Initial 24 hours Final
----------------------------------------------------------------------------------------------------------------
1 ------ ------ ------ ------ ------ ------
2 ------ ------ ------ ------ ------ ------
3 ------ ------ ------ ------ ------ ------
Average x ------ ------ ------ ------ ------ ------
----------------------------------------------------------------------------------------------------------------
Overall Percent Difference in Average x Capacitance:---------------------------- Conductance:
----------------------------
Water Penetration Test
----------------------------------------------------------------------------------------------------------------
Option A Option B
------------------------------------------------------------------------------
Penetration mm
End Leakage grams Weight Gain grams End Leakage grams (in.)
----------------------------------------------------------------------------------------------------------------
Control.......................... ---------- ---------- ---------- ----------
Heat Age......................... ---------- ---------- ---------- ----------
Humidity Exposure................ ---------- ---------- ---------- ----------
Temperature Cycling.............. ---------- ---------- ---------- ----------
----------------------------------------------------------------------------------------------------------------
Insulation Compression
------------------------------------------------------------------------
Failures
------------------------------------------------------------------------
Control................................... ----------------
Heat Age.................................. ----------------
Humidity Exposure......................... ----------------
Temperature Cycling....................... ----------------
------------------------------------------------------------------------
Jacket Slip Strength @ 50 deg.C
------------------------------------------------------------------------
Load in newtons (pound-
force)
------------------------------------------------------------------------
Control................................... ----------------
Heat Age.................................. ----------------
Humidity Exposure......................... ----------------
Temperature Cycling....................... ----------------
------------------------------------------------------------------------
Filler Exudation (grams)
------------------------------------------------------------------------
------------------------------------------------------------------------
Heat Age.................................. ----------------
Humidity Exposure......................... ----------------
Temperature Cycle......................... ----------------
------------------------------------------------------------------------
Surge Test (kilovolts)
------------------------------------------------------------------------
------------------------------------------------------------------------
Conductor to Conductor.................... ----------------
Shield to Conductors...................... ----------------
------------------------------------------------------------------------
Appendix B to Sec. 1755.860--Sheath Slitting Cord Qualification
(I) The test procedures described in this appendix are for
qualification of initial and subsequent changes in sheath slitting
cords.
(II) Sample Selection. All testing must be performed on two 1.2
meters (4 feet) lengths of wire removed sequentially from the same 3
pair, 22 gauge jacketed wire. This wire must not have been exposed to
temperatures in excess of 38 deg.C since its initial cool down after
sheathing.
(III) Test Procedure. (1) Using a suitable tool, expose enough of
sheath slitting cord to permit grasping with needle nose pliers.
(2) The prepared test specimens must be maintained at a temperature
of 23 1 deg.C for at least 4 hours immediately prior to and
during the test.
(3) Wrap the sheath slitting cord around the plier jaws to ensure a
good grip.
(4) Grasp and hold the wire in a convenient position while gently
and firmly pulling the sheath slitting cord longitudinally in the
direction away from the wire end. The angle of pull may vary to any
convenient and functional degree. A small starting notch is permissible.
(5) The sheath slitting cord is considered acceptable if the cord
can slit the jacket and/or shield for a continuous length of 0.6 meter
(2 feet) without breaking the cord.
[[Page 680]]
Appendix C to Sec. 1755.860--Thermal Reel Wrap Qualification
(I) The test procedures described in this appendix are for
qualification of initial and subsequent changes in thermal reel wraps.
(II) Sample Selection. All testing must be performed on two 450
millimeter (18 inch) lengths of wire removed sequentially from the same
3 pair, 22 gauge jacketed wire. This wire must not have been exposed to
temperatures in excess of 38 deg.C since its initial cool down after
sheathing.
(III) Test Procedure. (1) Place the two samples on an insulating
material such as wood, etc.
(2) Tape thermocouples to the jackets of each sample to measure the
jacket temperature.
(3) Cover one sample with the thermal reel wrap.
(4) Expose the samples to a radiant heat source capable of heating
the uncovered jacket sample to a minimum of 71 deg.C. A 600 watt
photoflood lamp or an equivalent lamp having the light spectrum
approximately that of the sun shall be used.
(5) The height of the lamp above the jacket shall be 380 millimeters
(15 inches) or a height that produces the 71 deg.C jacket temperature
on the unwrapped sample.
(6) After the samples have stabilized at the temperature, the jacket
temperatures of the samples must be recorded after one hour of exposure
to the heat source.
(7) Compute the temperature difference between the jackets.
(8) For the thermal reel wrap to be acceptable to RUS, the
temperature differences between the jacket with the thermal reel wrap
and the jacket without the reel wrap must be greater than or equal to 17
deg.C.
[58 FR 61004, Nov. 19, 1993, as amended at 60 FR 1711, Jan. 5, 1995]