ASTM B787/B787M-04(2009)

Standard Specification for 19 Wire Combination Unilay-Stranded Copper Conductors for Subsequent Insulation

ABSTRACT
This specification covers electrical contact alloys with the nominal composition of 75% silver, 24.5% copper, and 0.5% nickel in the form of rods, wires, strips, and sheets. Raw materials shall be of such quality and purity that the products, which shall be finished by such operations as cold working, heat treatment, annealing, turning, grinding, or pickling, shall adhere to the chemical composition and mechanical property requirements prescribed here. Besides analysis for the elements silver, copper, and nickel, further analysis is to be made for suspected or indicated impurities, such as zinc, iron, cadmium, and lead, to make sure that their total does not exceed specified limits. Mechanical tests, which are to be conducted at room temperature, shall evaluate the materials' tensile strength, elongation, Rockwell hardness, and area and thickness reduction.
SCOPE
1.1 This specification covers bare combination unilay-stranded conductors made from round copper wires, either uncoated or coated with tin or lead alloy for insulated conductors for electrical purposes. These conductors shall be constructed with a central core wire surrounded by two layers of helically laid wires, resulting in an outer diameter equal to the compressed-stranded equivalent conductor. (See Explanatory Note 1 and Note 2).
Note 1—For the purpose of this specification, combination unilay conductor is defined as follows: a central core wire surrounded by a layer of six helically laid wires of the same diameter as the core wire with a helically laid outer layer containing six smaller wires alternated between six wires of the same diameter as the wires in the layer underneath. Both layers have a common length and direction of lay (see Fig. 1).  
1.2 For the purpose of this specification, normal conductor classification (Class AA, A, B, C) is not applicable as these conductors are intended for subsequent insulation. The descriptive term combination unilay-stranded shall be used in place of conductor classification.
1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
1.3.1 For conductor sizes designated by AWG or kcmil, the requirements in SI units have been numerically converted from corresponding values, stated or derived, in inch-pound units.  
1.3.2 For conductor sizes designated by SI units only, the requirements are stated or derived in SI units.
1.3.3 For density, resistivity, and temperature, the values stated in SI units are to be regarded as standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 30-Sep-2009
• ICS: 29.060.20 - Cables
• Technical Committee: B01 - Electrical Conductors
• Drafting Committee: B01.04 - Conductors of Copper and Copper Alloys

Relations

• Replaces: ASTM B787/B787M-04 - Standard Specification for 19 Wire Combination Unilay-Stranded Copper Conductors for Subsequent Insulation
• Effective Date: 01-Oct-2009
• Replaced By: ASTM B787/B787M-04(2014) - Standard Specification for 19 Wire Combination Unilay-Stranded Copper Conductors for Subsequent Insulation
• Effective Date: 01-Sep-2014
• Referred By: ASTM B8-11(2017) - Standard Specification for Concentric-Lay-Stranded Copper Conductors, Hard, Medium-Hard, or Soft
• Effective Date: 01-Oct-2009
• Referred By: ASTM B226-11(2021) - Standard Specification for Cored, Annular, Concentric-Lay-Stranded Copper Conductors
• Effective Date: 01-Oct-2009

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:B787/B787M −04(Reapproved 2009)
Standard Specification for
19 Wire Combination Unilay-Stranded Copper Conductors
for Subsequent Insulation
This standard is issued under the fixed designation B787/B787M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
1.1 This specification covers bare combination unilay-
bility of regulatory limitations prior to use.
stranded conductors made from round copper wires, either
uncoated or coated with tin or lead alloy for insulated conduc-
2. Referenced Documents
tors for electrical purposes. These conductors shall be con-
2.1 The following documents of the issue in effect on date
structed with a central core wire surrounded by two layers of
of material purchase form a part of this specification to the
helically laid wires, resulting in an outer diameter equal to the
extent referenced herein.
compressed-stranded equivalent conductor. (See Explanatory
Note 1 and Note 2).
2.2 ASTM Standards:
B1Specification for Hard-Drawn Copper Wire
NOTE 1—For the purpose of this specification, combination unilay
B2Specification for Medium-Hard-Drawn Copper Wire
conductor is defined as follows: a central core wire surrounded by a layer
of six helically laid wires of the same diameter as the core wire with a B3Specification for Soft or Annealed Copper Wire
helically laid outer layer containing six smaller wires alternated between
B33Specification for Tin-Coated Soft or Annealed Copper
six wires of the same diameter as the wires in the layer underneath. Both
Wire for Electrical Purposes
layers have a common length and direction of lay (see Fig. 1).
B189Specification for Lead-Coated and Lead-Alloy-Coated
1.2 For the purpose of this specification, normal conductor
Soft Copper Wire for Electrical Purposes
classification (Class AA, A, B, C) is not applicable as these
B246Specification for Tinned Hard-Drawn and Medium-
conductorsareintendedforsubsequentinsulation.Thedescrip-
Hard-Drawn Copper Wire for Electrical Purposes
tivetermcombinationunilay-strandedshallbeusedinplaceof
B263Test Method for Determination of Cross-Sectional
conductor classification.
Area of Stranded Conductors
B354Terminology Relating to Uninsulated Metallic Electri-
1.3 The values stated in either SI units or inch-pound units
cal Conductors
are to be regarded separately as standard. The values stated in
each system may not be exact equivalents; therefore, each 2.3 Other Standard:
NBS Handbook 100—Copper Wire Tables of the National
system shall be used independently of the other. Combining
values from the two systems may result in non-conformance Bureau of Standards
with the standard.
3. Ordering Information
1.3.1 For conductor sizes designated byAWG or kcmil, the
requirementsinSIunitshavebeennumericallyconvertedfrom 3.1 Orders for materials under this specification shall in-
corresponding values, stated or derived, in inch-pound units. clude the following information:
1.3.2 For conductor sizes designated by SI units only, the 3.1.1 Quantity of each size,
requirements are stated or derived in SI units. 3.1.2 Conductor Size: Circular-mil area or American Wire
1.3.3 For density, resistivity, and temperature, the values Gage, AWG (Section 7 and Table 1),
stated in SI units are to be regarded as standard. 3.1.3 Stranding (see Explanatory Note 3),
3.1.4 Temper (see 4.2),
1.4 This standard does not purport to address all of the
3.1.5 Whether coated or uncoated; if coated, designate type
safety concerns, if any, associated with its use. It is the
of coating (see 4.1 and 4.2),
1 2
This specification is under the jurisdiction of ASTM Committee B01 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Electrical Conductors and is the direct responsibility of Subcommittee B01.04 on contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Conductors of Copper and Copper Alloys. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Oct. 1, 2009. Published January 2010. Originally the ASTM website.
approved in 1988. Last previous edition approved in 2004 as B787/B787M–04. Available from National Institute of Standards and Technology (NIST), 100
DOI: 10.1520/B0787_B0787M-04R09. Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B787/B787M−04 (2009)
4.2.4 Specification B1
4.2.5 Specification B189
4.2.6 Specification B246.
4.3 In combination unilay stranded conductors, the central
core wire shall be made of the same type and temper as the
layers, unless otherwise specified.
5. Joints
FIG. 1 Cross Section of Conductor
5.1 Welds and brazes may be made in rods or in wires prior
tofinaldrawing.Weldsandbrazesmaybemadeinthefinished
TABLE 1 Construction Requirements for 19-Wire Combination
Unilay Stranded Copper Conductors individual wires composing the conductor, but shall not be
closer together than 50 ft (15.24 m) for hard and medium-hard
Size, American (or
A B
Brown and
Wire D Wire D conductors, and 1 ft in a layer for soft conductors.
1 2
Cross-Sectional Area Sharpe) Diameter, Diameter,
cmil sq mm Wire Gage mils mm mils mm
6. Lay
500 000 253.4 175.6 4.5 128.5 3.3
450 000 228.0 166.6 4.2 121.9 3.1
6.1 For combination unilay conductors the lay of a layer of
400 000 202.7 157.1 4.0 115.0 2.9
wires shall be not less than 8 nor more than 16 times the
350 000 177.3 146.9 3.7 107.5 2.7
300 000 152.0 136.0 3.5 99.6 2.5
outside diameter of the outer layer.
250 000 126.7 124.2 3.2 90.9 2.3
6.2 Other lays for special purposes shall be furnished by
211 600 107.2 0000 114.2 2.4 83.6 2.1
167 800 85.0 000 101.7 2.6 74.5 1.9
specialagreementbetweenthemanufacturerandthepurchaser
133 100 67.4 00 90.6 2.3 66.3 1.7
(Explanatory Note 4).
105 600 53.5 0 80.7 2.0 59.1 1.5
83 690 42.4 1 71.8 1.8 52.6 1.3
6.3 The direction of lay shall be left-hand unless the
66 360 33.6 2 64.0 1.6 46.8 1.2
direction of lay is specified otherwise by the purchaser.
52 620 26.7 3 57.0 1.4 41.7 1.1
41 740 21.1 4 50.7 1.3 37.1 0.9
33 090 16.8 5 45.2 1.1 33.1 0.8 7. Construction (Explanatory Note 3)
26 240 13.3 6 40.2 1.0 29.4 0.7
7.1 The cross-sectional areas, numbers, and diameters of
20 820 10.5 7 35.8 0.9 26.2 0.7
16 510 8.4 8 31.9 0.8 23.4 0.6
wires in the various conductors shall conform to the require-
13 090 6.6 9 28.4 0.7 20.8 0.5
ments prescribed in Table 1.
10 380 5.3 10 25.3 0.6 18.5 0.5
6530 3.3 12 20.1 0.5 14.7 0.4
7.2 ThediametersofthewireslistedinTable2arenominal.
4110 2.1 14 15.9 0.4 11.7 0.3
In order to produce an essentially round 19-wire construction,
2580 1.3 16 12.6 0.3 9.2 0.2
1620 0.8 18 10.0 0.3 7.3 0.2 the outer 12-wire layer in the combination unilay product is
1020 0.5 20 7.9 0.2 5.8 0.1
comprised of 6 wires of the same diameter as the wires in the
640 0.3 22 6.3 0.2 4.6 0.1
7-wire core, and 6 wires approximately 25% smaller. The
404 0.2 24 5.0 0.1 3.7 0.1
2-wire sizes are alternated around the 7-wire core (Fig. 1).
A
Equation to calculate D :
Cross2Sectional Area
8. Physical and Electrical Tests of Conductors Stranded
Œ
16.2149
of Soft Wires
B
Equation to calculate D : D × 0.732.
2 1
8.1 Tests for the electrical properties of wires composing
conductors made from soft or annealed copper wire, bare or
coated, shall be made before stranding.
3.1.6 Details of special-purpose lays, if required (see 6.2),
8.2 Tests for the physical properties of soft or annealed
3.1.7 When physical tests shall be made (see 9.2 and 9.3),
copper wire, bare or coated, may be made upon the wires
3.1.8 Package size (see 15.1),
before stranding or upon wires removed from the complete
3.1.9 Lagging, if required (see 15.2),
strandedconductor,butneednotbemadeuponboth.Careshall
3.1.10 Special package marking, if required (Section 15),
be taken to avoid mechanical injury to wire removed from the
and
conductor for the purpose of testing.
3.1.11 Place of inspection (Section 13).
8.3 The physical properties of wire when tested before
4. Requirements for Wires
stranding shall conform to the applicable requirements of 4.2.
4.1 The purchaser shall designate the type of wire and the
8.4 The physical properties of wires removed from the
kind of coating, if any, to be used in the conductor.
completed stranded conductor shall be permitted to vary from
4.2 Before stranding, the copper wire used shall meet all of the applicable requirements of 4.2 by the amounts as follows
therequirementsofthefollowingASTMspecificationsthatare (Explanatory Note 5):
applicable to its type: 8.4.1 AverageofResultsObtainedonAllWiresTested—The
4.2.1 Specification B3 minimum elongation required shall be reduced in numerical
4.2.2 Specification B33 value 5 (for example, from 30 to 25%) from the numerical
4.2.3 Specification B2 requirements for the wire before stranding.
B787/B787M−04 (2009)
TABLE 2 Diameters, Areas, and Masses of 19-Wire Combination Unilay Stranded Copper Conductors
Nominal Area Mass
Size of Conductor
A 2 2
cmil or AWG sq mm Nominal Diameter, in. Conductor, mm in. mm lbs/1000 ft lbs/mile g/m
500 000 253.4 0.784 19.914 0.392700 253.35 1544 8151 2297
450 000 228.0 0.744 18.878 0.353400 228.02 1389 7336 2067
400 000 202.7 0.701 17.805 0.314000 202.68 1235 6521 1838
350 000 177.3 0.656 16.662 0.274900 177.35 1081 5706 1609
300 000 152.0 0.607 15.418 0.235600 152.01 926.3 4891 1378
250 000 126.7 0.554 14.072 0.196300 126.68 771.9 4076 1149
0000 107.2 0.510 12.954 0.166200 107.22 653.3 3450 972.1
000 85.0 0.454 11.532 0.131800 85.02 518.1 2736 770.9
00 67.4 0.404 10.262 0.104500 67.44 410.9 2169 611.4
0 53.5 0.360 9.144 0.082910 53.51 325.8 1720 684.8
1 42.4 0.321 8.153 0.065730 42.41 258.4 1364 384.5
2 33.6 0.286 7.264 0.052120 33.62 204.9 1082 304.9
3 26.7 0.254 6.452 0.041330 26.77 162.5 858.1 241.8
4 21.1 0.226 5.740 0.032780 21.15 128.9 680.5 191.8
5 16.8 0.202 5.131 0.025990 16.77 102.2 539.6 152.1
6 13.3 0.179 4.547 0.020610 13.30 81.05 428.0 120.6
7 15.6 0.160 4.064 0.016350 10.55 64.28 339.4 95.65
8 8.4 0.143 3.632 0.012970 8.37 50.97 269.1 75.84
9 6.6 0.127 3.226 0.010280 6.63 40.42 213.4 60.14
10 5.3 0.113 2.870 0.008155 5.26 32.06 169.3 47.71
12 3.3 0.090 2.286 0.005130 3.31 20.16 106.5 30.00
14 2.1 0.071 1.803 0.003230 2.08 12.68 66.95 18.87
16 1.3 0.056 1.422 0.002030 1.31 7.974 42.10 11.87
18 0.8 0.045 1.143 0.001280 0.82 5.015 26.48 7.462
20 0.5 0.035 0.809 0.000804 0.52 3.154 16.65 4.693
22 0.3 0.028 0.703 0.000503 0.32 1.992 10.52 2.964
24 0.2 0.022 0.558 0.000317 0.20 1.249 6.59 1.859
A
To calculate the diameter, multiply the large wire diameter in Table 1 by 3 and add two times the small wire diameter.
Example: AWG 4/0 diameter = [(3(114.2) + 2 (83.6)] = 509.8
8.4.2 ResultsObtainedonIndividualWires—Theelongation sum of the specified maximum breaking strengths of the
ofindividualwiresshallbereducedinnumericalvalue15from component wires. The minimum breaking strengths of wires
the minimum requirements before stranding (that is, 10 in shall be calculated using specified nominal diameters and
addition to the 5 allowed in 8.4.1), but in no case shall the specified minimum tensile strengths. The maximum breaking
elongation of any individual wire be less than 5%. strengths of wires shall be calculated using nominal diameters
and specified maximum tensile strengths. The free length
8.5 Intheeventthattherequirementsprescribedin8.4.2are
between grips of the test specimen shall be not less than 24 in.
met but those prescribed in 8.4.1 are not met, a retest shall be
(610 mm), and care shall be taken to ensure that the wires in
permittedwhereinallwiresoftheconductorshallbetestedfor
the conductor are evenly gripped during the test (Explanatory
the purpose of final determination of conformance to 8.4.
Note 6).
8.6 Elongation tests to determine compliance shall not be
9.3 When requested by the purchaser at the time of placing
made on the conductor as a unit.
theorder,tensiontestsonhard-drawnandmedium-hard-drawn
8.7 If a tinning or lead-alloy-coating test is required, it shall
wires,uncoatedorcoated,beforestrandingorasaunitmaybe
be made on the wires prior to stranding.
waived and tests made on wires removed from the completed
conductor. The test limits, based on a 10-in. (254-mm) gage
9. Physical and Electrical Tests of Conductors Stranded
length, for such tests shall be specified by the purchaser in the
of Hard-Drawn or Medium-Hard Drawn Wires
placing of individual orders (Explanatory Note 5).
9.1 Tests for the physical and electrical properties of wires
9.4 Ifatinningtestisrequired,itshallbemadeonthewires
composing conductors made from hard-drawn or medium-
prior to stranding.
hard-drawnwires,uncoatedorcoated,shallbemadebeforebut
not after stranding.
10. Density
9.2 At the option of the purchaser, tension and elongation
10.1 For the purpose of calculating masses, cross sections,
tests on hard-drawn and medium-hard-drawn wires, uncoated
and so forth, the density of the copper shall be taken as 8.89
3 3
or coated, before stranding may be waived, and the completed
g/cm (0.32117 lb/in. ) at 20°C (Explanatory Note 7).
hard-drawnandmedium-hard-drawnconductorsmaybetested
11. Mass and Resistance
asaunit.Thebreakingstrengthofthebareconductorssotested
shall be at least 90% of the total of the specified minimum 11.1 The mass and electrical resistance of a unit length of
breaking strengths of the component wires. The maximum stranded conductor are a function of the length of lay. The
breaking strength of conductors made from medium-hard- approximate mass and electrical resistance may be determined
drawn wires, uncoated or coated, shall be not greater than the using the standard increment of 2%.When greater accuracy is
B787/B787M−04 (2009)
desired, the increment based on the specific lay of the conduc- 13.3 The manufacturer shall afford the inspector represent-
tor may be calculated (Explanatory Note 8). ing the purchaser all reasonable manufacturer’s facilities to
satisfy him that the material is being furnished in accordance
12. Variance in Area
with this specification.
12.1 The cross-sectional area of the completed conductor
shall be not less than 98% of the area indicated in Column 1 14. Product Marking
of Table 1. Unless otherwise specified by the purchaser, the
14.1 The net weight, length (or lengths and numb
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