ASTM B787/B787M-01

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Designation: B 787/B 787M – 01
Standard Specification for
19 Wire Combination Unilay-Stranded Copper Conductors
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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).
NOTE 1—For the purpose of this specification, combination unilay
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B 1 Specification for Hard-Drawn Copper Wire
conductor is defined as follows: a central core wire surrounded by a layer
2
B 2 Specification for Medium-Hard-Drawn Copper Wire
of six helically laid wires of the same diameter as the core wire with a
2
B 3 Specification for Soft or Annealed Copper Wire
helically laid outer layer containing six smaller wires alternated between
B 33 Specification for Tinned Soft or Annealed Copper
six wires of the same diameter as the wires in the layer underneath. Both
2
layers have a common length and direction of lay (see Fig. 1).
Wire for Electrical Purposes
B 189 Specification for Lead-Coated and Lead-Alloy-
1.2 For the purpose of this specification, normal conductor
2
Coated Soft Copper Wire for Electrical Purposes
classification (Class AA, A, B, C) is not applicable as these
B 246 Specification for Tinned Hard-Drawn and Medium-
conductors are intended for subsequent insulation. The descrip-
2
Hard-Drawn Copper Wire for Electrical Purposes
tive term combination unilay-stranded shall be used in place of
B 263 Test Method for Determination of Cross-Sectional
conductor classification.
2
Area of Stranded Conductors
1.3 The values stated in inch-pound or SI units are to be
B 354 Terminology Relating to Uninsulated Metallic Elec-
regarded separately as standard. Each system shall be used
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trical Conductors
independently of the other. Combining values from the two
2.3 Other Standard:
systems may result in nonconformance with the specification.
NBS Handbook 100—Copper Wire Tables of the National
For conductor sizes designated by AWG or kcmil, the require-
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Bureau of Standards
ments in SI units have been numerically converted from
corresponding values, stated or derived, in inch-pound units.
3. Ordering Information
For conductor sizes designated by SI units only, the require-
3.1 Orders for materials under this specification shall in-
ments are stated or derived in SI units.
clude the following information:
1.3.1 For density, resistivity, and temperature, the values
3.1.1 Quantity of each size,
stated in SI units are to be regarded as standard.
3.1.2 Conductor Size: Circular-mil area or American Wire
2. Referenced Documents Gage, AWG (Section 7 and Table 1),
3.1.3 Stranding (see Explanatory Note 3),
2.1 The following documents of the issue in effect on date
3.1.4 Temper (see 4.2),
of material purchase form a part of this specification to the
3.1.5 Whether coated or uncoated; if coated, designate type
extent referenced herein.
of coating (see 4.1 and 4.2),
2.2 ASTM Standards:
3.1.6 Details of special-purpose lays, if required (see 6.2),
3.1.7 When physical tests shall be made (see 9.2 and 9.3),
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This specification is under the jurisdiction of ASTM Committee B01 on
Electrical Conductors and is the direct responsibility of Subcommittee B01.04 on
2
Conductors of Copper and Copper Alloys. Annual Book of ASTM Standards, Vols 02.03.
3
Current edition approved Nov. 10, 2001. Published January 2002. Originally Available from National Institute of Standards and Technology, (NIST),
published as B 787 – 88. Last previous edition B 787/B 787M – 00. Gaithersburg, MD 20899.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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B 787/B 787M
TABLE 1 Construction Requirements for 19-Wire Combination
6. Lay
Unilay Stranded Copper Conductors
6.1 For combination unilay conductors the lay of a layer of
Size, American (or
A B
wires shall be not less than 8 nor more than 16 times the
Brown and Wire D Wire D
1 2
Cross-Sectional Area Sharpe) Diameter, Diameter,
outside diameter of the outer layer.
cmil sq mm Wire Gage mils mm mils mm
6.2 Other lays for special purposes shall be furnished by
500 000 2
...