ASTM B787/B787M-00
(Specification)Standard Specification for 19 Wire Combination Unilay-Stranded Copper Conductors for Subsequent Insulation
Standard Specification for 19 Wire Combination Unilay-Stranded Copper Conductors for Subsequent Insulation
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 inch-pound or SI units are to be regarded separately as standard. Each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the specification. 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. For conductor sizes designated by SI units only, the requirements are stated or derived in SI units.
1.3.1 For density, resistivity, and temperature, the values stated in SI units are to be regarded as standard.
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Designation: B 787/B 787M – 00
Standard Specification for
19 Wire Combination Unilay-Stranded Copper Conductors
for Subsequent Insulation
This standard is issued under the fixed designation B 787/B 787M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. 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 conduc-
tors for electrical purposes. These conductors shall be con-
structed 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
FIG. 1 Cross Section of Conductor
Note 1 and Note 2).
B 2 Specification for Medium-Hard-Drawn Copper Wire
NOTE 1—For the purpose of this specification, combination unilay
B 3 Specification for Soft or Annealed 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 B 33 Specification for Tinned Soft or Annealed Copper
helically laid outer layer containing six smaller wires alternated between
Wire for Electrical Purposes
six wires of the same diameter as the wires in the layer underneath. Both
B 189 Specification for Lead-Coated and Lead-Alloy-
layers have a common length and direction of lay (see Fig. 1).
Coated Soft Copper Wire for Electrical Purposes
1.2 For the purpose of this specification, normal conductor
B 246 Specification for Tinned Hard-Drawn and Medium-
classification (Class AA, A, B, C) is not applicable as these
Hard-Drawn Copper Wire for Electrical Purposes
conductors are intended for subsequent insulation. The descrip-
B 263 Test Method for Determination of Cross-Sectional
tive term combination unilay-stranded shall be used in place of
Area of Stranded Conductors
conductor classification.
B 354 Terminology Relating to Uninsulated Metallic Elec-
1.3 The values stated in inch-pound or SI units are to be
trical Conductors
regarded separately as standard. Each system shall be used
2.3 Other Standard:
independently of the other. Combining values from the two
NBS Handbook 100—Copper Wire Tables of the National
systems may result in nonconformance with the specification.
Bureau of Standards
For conductor sizes designated by AWG or kcmil, the require-
3. Ordering Information
ments in SI units have been numerically converted from
corresponding values, stated or derived, in inch-pound units. 3.1 Orders for materials under this specification shall in-
For conductor sizes designated by SI units only, the require- clude the following information:
ments are stated or derived in SI units.
3.1.1 Quantity of each size,
1.3.1 For density, resistivity, and temperature, the values 3.1.2 Conductor Size: Circular-mil area or American Wire
stated in SI units are to be regarded as standard.
Gage, AWG (Section 7 and Table 1),
3.1.3 Stranding (see Explanatory Note 3),
2. Referenced Documents
3.1.4 Temper (see 4.2),
2.1 The following documents of the issue in effect on date
3.1.5 Whether coated or uncoated; if coated, designate type
of material purchase form a part of this specification to the
of coating (see 4.1 and 4.2),
extent referenced herein.
3.1.6 Details of special-purpose lays, if required (see 6.2),
2.2 ASTM Standards:
3.1.7 When physical tests shall be made (see 9.2 and 9.3),
B 1 Specification for Hard-Drawn Copper Wire
3.1.8 Package size (see 15.1),
3.1.9 Lagging, if required (see 15.2),
3.1.10 Special package marking, if required (Section 15),
This specification is under the jurisdiction of ASTM Committee B01 on
Electrical Conductors and is the direct responsibility of Subcommittee B01.04 on and
Conductors of Copper and Copper Alloys.
Current edition approved Oct. 10, 2000. Published December 2000. Originally
published as B 787 – 88. Last previous edition B 787 – 93. Available from National Institute of Standards and Technology, (NIST),
Annual Book of ASTM Standards, Vols 02.03. Gaithersburg, MD 20899.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
B 787/B 787M
TABLE 1 Construction Requirements for 19-Wire Combination
6.2 Other lays for special purposes shall be furnished by
Unilay Stranded Copper Conductors
special agreement between the manufacturer and the purchaser
Size, American (or
(Explanatory Note 4).
A B
Area of Cross Brown and Wire D Wire D
1 2
6.3 The direction of lay shall be left-hand unless the
Section Sharpe) Diameter, Diameter,
direction of lay is specified otherwise by the purchaser.
cmil sq mm Wire Gage mils mm mils mm
500 000 253.4 175.6 4.5 128.5 3.3
7. Construction (Explanatory Note 3)
450 000 228.0 166.6 4.2 121.9 3.1
400 000 202.7 157.1 4.0 115.0 2.9
7.1 The areas of cross section, numbers, and diameters of
350 000 177.3 146.9 3.7 107.5 2.7
wires in the various conductors shall conform to the require-
300 000 152.0 136.0 3.5 99.6 2.5
250 000 126.7 124.2 3.2 90.9 2.3 ments prescribed in Table 1.
211 600 107.2 0000 144.2 3.7 83.6 2.1
7.2 The diameters of the wires listed in Table 2 are nominal.
167 800 85.0 000 101.7 2.6 74.5 1.9
In order to produce an essentially round 19-wire construction,
133 100 67.4 00 90.6 2.3 66.3 1.7
105 600 53.5 0 80.7 2.0 59.1 1.5
the outer 12-wire layer in the combination unilay product is
83 690 42.4 1 71.8 1.8 52.6 1.3
comprised of 6 wires of the same diameter as the wires in the
66 360 33.6 2 64.0 1.6 46.8 1.2
7-wire core, and 6 wires approximately 25 % smaller. The
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
2-wire sizes are alternated around the 7-wire core (Fig. 1).
33 090 16.8 5 45.2 1.1 33.1 0.8
26 240 13.3 6 40.2 1.0 29.4 0.7
8. Physical and Electrical Tests of Conductors Stranded
30 820 15.6 7 35.8 0.9 26.2 0.7
of Soft Wires
16 510 8.4 8 31.9 0.8 23.4 0.6
13 090 6.6 9 28.4 0.7 20.8 0.5
8.1 Tests for the electrical properties of wires composing
10 380 5.3 10 25.3 0.6 18.5 0.5
conductors made from soft or annealed copper wire, bare or
6 530 3.3 12 20.1 0.5 14.7 0.4
4 110 2.1 14 15.9 0.4 11.7 0.3 coated, shall be made before stranding.
2 580 1.3 16 12.6 0.3 9.2 0.2
8.2 Tests for the physical properties of soft or annealed
1 620 0.8 18 10.0 0.3 7.3 0.2
copper wire, bare or coated, may be made upon the wires
1 020 0.5 20 7.9 0.2 5.8 0.1
640 0.3 22 6.3 0.2 4.6 0.1
before stranding or upon wires removed from the complete
404 0.2 24 5.0 0.1 3.7 0.1
stranded conductor, but need not be made upon both. Care shall
A
Equation to calculate D :
be taken to avoid mechanical injury to wire removed from the
Area of Cross Section ~cmil!
conductor for the purpose of testing.
˛
16.2149
B
8.3 The physical properties of wire when tested before
Equation to calculate D := D 3 0.732.
2 1
stranding shall conform to the applicable requirements of 4.2.
8.4 The physical properties of wires removed from the
3.1.11 Place of inspection (Section 13).
completed stranded conductor shall be permitted to vary from
4. Requirements for Wires
the applicable requirements of 4.2 by the amounts as follows
(Explanatory Note 5):
4.1 The purchaser shall designate the type of wire and the
8.4.1 Average of Results Obtained on All Wires Tested—The
kind of coating, if any, to be used in the conductor.
minimum elongation required shall be reduced in numerical
4.2 Before stranding, the copper wire used shall meet all of
value 5 (for example, from 30 to 25 %) from the numerical
the requirements of the following ASTM specifications that are
requirements for the wire before stranding.
applicable to its type:
8.4.2 Results Obtained on Individual Wires—The elonga-
4.2.1 Specification B 3
tion of individual wires shall be reduced in numerical value 15
4.2.2 Specification B 33
from the minimum requirements before stranding (that is, 10 in
4.2.3 Specification B 2
addition to the 5 allowed in 8.4.1), but in no case shall the
4.2.4 Specification B 1
elongation of any individual wire be less than 5 %.
4.2.5 Specification B 189
8.5 In the event that the requirements prescribed in 8.4.2 are
4.2.6 Specification B 246.
met but those prescribed in 8.4.1 are not met, a retest shall be
4.3 In combination unilay stranded conductors the central
permitted wherein all wires of the conductor shall be tested for
core wire shall be made of the same type and temper as the
the purpose of final determination of conformance to 8.4.
layers, unless otherwise specified.
8.6 Elongation tests to determine compliance shall not be
5. Joints
made on the conductor as a unit.
5.1 Welds and brazes may be made in rods or in wires prior 8.7 If a tinning or lead-alloy-coating test is required, it shall
be made on the wires prior to stranding.
to final drawing. Welds and brazes may be made in the finished
individual wires composing the conductor, but shall not be
9. Physical and Electrical Tests of Conductors Stranded
closer together than 50 ft (15.24 m) for hard and medium-hard
of Hard-Drawn or Medium-Hard Drawn Wires
conductors, and 1 ft in a layer for soft conductors.
9.1 Tests for the physical and electrical properties of wires
6. Lay
composing conductors made from hard-drawn or medium-
6.1 For combination unilay conductors the lay of a layer of hard-drawn wires, uncoated or coated, shall be made before but
wires shall be not less than 8 nor more than 16 times the not after stranding.
outside diameter of the outer layer. 9.2 At the option of the purchaser, tension and elongation
B 787/B 787M
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 kg/m
500 000 253.4 0.784 19.9 0.392700 253.4 1544 8151 2.297
450 000 228.0 0.744 18.9 0.353400 228.0 1389 7336 2.067
400 000 202.7 0.701 17.8 0.314000 202.6 1235 6521 1.838
350 000 177.3 0.656 16.7 0.274900 177.4 1081 5706 1.609
300 000 152.0 0.607 15.4 0.235600 152.0 926.3 4891 1.378
250 000 126.7 0.554 14.1 0.196300 126.7 771.9 4076 1.149
0000 107.2 0.510 13.0 0.166200 107.2 653.3 3450 0.972
000 85.0 0.454 11.5 0.131800 85.0 518.1 2736 0.771
00 67.4 0.404
...
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