ASTM B8-23

Standard Specification for Concentric-Lay-Stranded Copper Conductors, Hard, Medium-Hard, or Soft

ABSTRACT
This specification covers standard requirements for bare-concentric-lay stranded conductors made from round copper wires, either uncoated or coated with tin, lead, or lead alloy for general use for electrical purposes. These conductors shall be constructed with a central core surrounded by one or more layers of helically laid wires. The conductors shall be classified as follows: Class AA, Class A, Class B, Class C, and Class D. Sizes, number of wires, and diameter of wires in the various classes of concentric-lay-stranded conductors shall conform to the prescribed requirements. Welds and brazes may be made in rods or in wires prior to final drawing. The completed conductor of varying classes shall conform to the minimum distance required between the joints. Diameters, areas, and mass of concentric-lay-stranded copper conductors shall conform to the prescribed requirements. Physical and electrical tests of conductors stranded of hard-drawn or medium-hard-drawn wires shall be conducted before but not after stranding. The approximate mass and electrical resistance may be determined using the required increments. The material shall also conform to the temperature corrections factor for conductor resistance.
SCOPE
1.1 This specification covers bare concentric-lay-stranded conductors made from round copper wires, either uncoated or coated with tin, lead, or lead alloy for general use for electrical purposes. These conductors shall be constructed with a central core surrounded by one or more layers of helically laid wires.  
Note 1: This specification also permits conductors for use as covered or insulated electrical conductors.
Note 2: Sealed conductors, that are intended to prevent longitudinal water propagation and are further covered/insulated, are also permitted within the guidelines of this specification.  
1.2 For the purposes of this specification, conductors are classified as follows (Explanatory Note 1 and Note 2):  
1.2.1 Class AA—For bare conductors usually used in overhead lines.  
1.2.2 Class A—For conductors to be covered with weather-resistant (weather-proof), slow-burning materials, and for bare conductors where greater flexibility than is afforded by Class AA is required.  
1.2.3 Class B—For conductors to be insulated with various materials such as rubber, paper, varnished cloth, and so forth, and for the conductors indicated under Class A where greater flexibility is required.  
1.2.4 Class C and Class D—For conductors where greater flexibility is required than is provided by Class B conductors.  
1.3 The SI values for density are regarded as the standard. For all other properties, the inch-pound values are to be regarded as standard and the SI units may be approximate.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Oct-2023
• ICS: 29.060.20 - Cables
• Technical Committee: B01 - Electrical Conductors
• Drafting Committee: B01.04 - Conductors of Copper and Copper Alloys

Relations

• Replaces: ASTM B8-11(2017) - Standard Specification for Concentric-Lay-Stranded Copper Conductors, Hard, Medium-Hard, or Soft
• Effective Date: 01-Nov-2023
• Refers: ASTM B3-13(2024) - Standard Specification for Soft or Annealed Copper Wire
• Effective Date: 01-Apr-2024
• Refers: ASTM B3-13(2018) - Standard Specification for Soft or Annealed Copper Wire
• Effective Date: 01-Oct-2018
• Referred By: ASTM B226-11(2021) - Standard Specification for Cored, Annular, Concentric-Lay-Stranded Copper Conductors
• Effective Date: 01-Nov-2023
• Referred By: ASTM B173-17 - Standard Specification for Rope-Lay-Stranded Copper Conductors Having Concentric-Stranded Members, for Electrical Conductors
• Effective Date: 01-Nov-2023
• Referred By: ASTM F1883-20 - Standard Practice for Selection of Wire and Cable Size in AWG or Metric Units
• Effective Date: 01-Nov-2023
• Referred By: ASTM B913-21 - Standard Test Method for Evaluation of Crimped Electrical Connections to 16-Gauge and Smaller Diameter Stranded and Solid Conductors
• Effective Date: 01-Nov-2023
• Referred By: ASTM B784-01(2017)e1 - Standard Specification for Modified Concentric-Lay-Stranded Copper Conductors for Use in Insulated Electrical Cables
• Effective Date: 01-Nov-2023
• Referred By: ASTM F1835-97(2018) - Standard Guide for Cable Splicing Installations
• Effective Date: 01-Nov-2023

Overview

ASTM B8-23 is the Standard Specification for Concentric-Lay-Stranded Copper Conductors, Hard, Medium-Hard, or Soft. Published by ASTM International, this standard outlines requirements for bare concentric-lay-stranded conductors constructed from round copper wires, either uncoated or coated with tin, lead, or lead alloy. The specification covers conductors designed for general electrical use, including applications where the conductors may subsequently be covered or insulated for specific purposes. By establishing uniform requirements for conductor construction, mass, resistance, and testing, ASTM B8-23 supports performance consistency and quality in electrical and utility installations worldwide.

Key Topics

• Conductor Types: Includes hard-drawn, medium-hard-drawn, and soft copper wires.
• Coatings: Permits uncoated wires as well as wires coated with tin, lead, or lead alloy.
• Stranding Construction: Requires concentric-lay stranding, where a central core is surrounded by one or more layers of helically laid wires.
• Classification: Divides conductors into five classes based on intended application and flexibility-Class AA, A, B, C, and D.
  • Class AA: Primarily for bare conductors, often for overhead transmission lines.
  • Class A: For conductors to be covered with weather-resistant materials or requiring more flexibility than Class AA.
  • Class B: Suitable for insulation with various materials and offers additional flexibility.
  • Class C & D: Provide even greater flexibility for specialized uses.
• Physical and Electrical Testing: Details when and how to test for mechanical and electrical properties, focusing on wire performance before and after stranding.
• Size and Construction Consistency: Specifies sizes, number of wires, diameters, mass, and minimum distances between joints, ensuring quality control.
• Testing and Compliance: Addresses mass and electrical resistance requirements, temperature correction factors for resistance, and inspection procedures.

Applications

ASTM B8-23 is widely referenced in industries that demand high-quality electrical conductors, including:

• Electric Power Transmission and Distribution: Commonly used for overhead power lines and utility applications, especially where flexibility or corrosion resistance is required.
• Building Wiring: Applied in construction where bare or covered conductors are needed, and where specific flexibility classes are selected based on installation needs.
• Industrial Installations: Ensures reliable performance of copper conductors in machinery, control panels, and other heavy-duty applications.
• Telecommunications: Useful in signal transmission systems that require strict standards for wire consistency, resistance, and mass.
• Cable Manufacturing: Forms the basis for the selection and specification of copper conductors for further insulation and assembly into multi-conductor cables.

Related Standards

Several other ASTM standards address copper conductors and associated materials:

• ASTM B1: Specification for Hard-Drawn Copper Wire
• ASTM B2: Specification for Medium-Hard-Drawn Copper Wire
• ASTM B3: Specification for Soft or Annealed Copper Wire
• ASTM B33: Specification for Tin-Coated Soft or Annealed Copper Wire for Electrical Purposes
• ASTM B172, B173: Specifications for rope-lay-stranded copper conductors
• ASTM B174: Specification for Bunch-Stranded Copper Conductors for Electrical Conductors
• ASTM B189: Specification for Lead-Coated and Lead-Alloy-Coated Soft Copper Wire
• ASTM B246: Specification for Tinned Hard-Drawn and Medium-Hard-Drawn Copper Wire
• ASTM B263: Test Method for Determination of Cross-Sectional Area of Stranded Conductors
• ASTM B787/B787M: Specification for 19 Wire Combination Unilay-Stranded Copper Conductors

Practical Value

ASTM B8-23 enables manufacturers, engineers, and specifiers to select and procure copper conductors with confidence, knowing they meet robust standards for physical and electrical properties. This ensures safety, efficiency, and durability in critical electrical infrastructure, supporting reliable power delivery and system performance across residential, commercial, and industrial applications.

Keywords: concentric-lay-stranded copper conductors, ASTM B8-23, hard copper conductor, medium-hard copper conductor, soft copper conductor, bare stranded conductor, electrical conductor specification, copper wire standard, utility conductors, overhead line copper conductors.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: B8 − 23
Standard Specification for
Concentric-Lay-Stranded Copper Conductors, Hard,
Medium-Hard, or Soft
This standard is issued under the fixed designation B8; 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 (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope 2. Referenced Documents
1.1 This specification covers bare concentric-lay-stranded 2.1 ASTM Standards:
conductors made from round copper wires, either uncoated or B1 Specification for Hard-Drawn Copper Wire
coated with tin, lead, or lead alloy for general use for electrical B2 Specification for Medium-Hard-Drawn Copper Wire
purposes. These conductors shall be constructed with a central B3 Specification for Soft or Annealed Copper Wire
core surrounded by one or more layers of helically laid wires. B33 Specification for Tin-Coated Soft or Annealed Copper
Wire for Electrical Purposes
NOTE 1—This specification also permits conductors for use as covered
B172 Specification for Rope-Lay-Stranded Copper Conduc-
or insulated electrical conductors.
tors Having Bunch-Stranded Members, for Electrical Con-
NOTE 2—Sealed conductors, that are intended to prevent longitudinal
water propagation and are further covered/insulated, are also permitted
ductors
within the guidelines of this specification.
B173 Specification for Rope-Lay-Stranded Copper Conduc-
1.2 For the purposes of this specification, conductors are tors Having Concentric-Stranded Members, for Electrical
classified as follows (Explanatory Note 1 and Note 2): Conductors
1.2.1 Class AA—For bare conductors usually used in over- B174 Specification for Bunch-Stranded Copper Conductors
head lines. for Electrical Conductors
1.2.2 Class A—For conductors to be covered with weather- B189 Specification for Lead-Coated and Lead-Alloy-Coated
resistant (weather-proof), slow-burning materials, and for bare Soft Copper Wire for Electrical Purposes
conductors where greater flexibility than is afforded by Class B193 Test Method for Resistivity of Electrical Conductor
AA is required. Materials
1.2.3 Class B—For conductors to be insulated with various B246 Specification for Tinned Hard-Drawn and Medium-
materials such as rubber, paper, varnished cloth, and so forth, Hard-Drawn Copper Wire for Electrical Purposes
and for the conductors indicated under Class A where greater B263 Test Method for Determination of Cross-Sectional
flexibility is required. Area of Stranded Conductors
1.2.4 Class C and Class D—For conductors where greater B354 Terminology Relating to Uninsulated Metallic Electri-
flexibility is required than is provided by Class B conductors. cal Conductors
B787/B787M Specification for 19 Wire Combination
1.3 The SI values for density are regarded as the standard.
Unilay-Stranded Copper Conductors for Subsequent Insu-
For all other properties, the inch-pound values are to be
lation
regarded as standard and the SI units may be approximate.
E29 Practice for Using Significant Digits in Test Data to
1.4 This international standard was developed in accor-
Determine Conformance with Specifications
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
3. Ordering Information
Development of International Standards, Guides and Recom-
3.1 Orders for material under this specification shall include
mendations issued by the World Trade Organization Technical
the following information:
Barriers to Trade (TBT) Committee.
3.1.1 Quantity of each size and class,
3.1.2 Conductor size: circular-mil area or AWG (Section 6),
This specification is under the jurisdiction of ASTM Committee B01 on
Electrical Conductors and is the direct responsibility of Subcommittee B01.04 on
Conductors of Copper and Copper Alloys. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2023. Published November 2023. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1915. Last previous edition approved in 2017 as B8 – 11 (2017). DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/B0008-23. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B8 − 23
3.1.3 Class (see 1.2 and Table 1), 3.1.11 Place of inspection (see Section 15).
3.1.4 Temper (see 14.2),
4. Joints
3.1.5 Whether coated or uncoated; if coated, designate type
of coating (see 14.1 and 14.2), 4.1 Welds and brazes may be made in rods or in wires prior
3.1.6 Details of special-purpose lays, if required (see 5.5), to final drawing. Joints may not be made in the finished wires
3.1.7 When physical tests shall be made (see Sections 7 and composing hard-drawn or medium-hard-drawn Class AA con-
9), ductors of seven wires or less. In other conductors, welds and
3.1.8 Package size (see Section 16), brazes may be made in the finished individual wires composing
3.1.9 Lagging, if required (see section 16.2), the conductor, but shall not be closer together than prescribed
3.1.10 Special package marking, if required (see 16.3), and in Table 2.
TABLE 1 Construction Requirements of Concentric-Lay-Stranded Copper Conductors
A
Area of Size, Class AA Class A Class B Class C Class D
Cross-Section, American
Number of Diameter of Number of Diameter of Number of Diameter of Number of Diameter of Number of Diameter of
cmil Wire Gauge
Wires Wires, mils Wires Wires, mils Wires Wires, mils Wires Wires, mils Wires Wires, mils
*5 000 000 . . . 169 172.0 217 151.8 271 135.8 271 135.8
4 500 000 . . . 169 163.2 217 144.0 271 128.9 271 128.9
4 000 000 . . . 169 153.8 217 135.8 271 121.5 271 121.5
3 500 000 . . . 127 166.0 169 143.9 217 127.0 271 113.6
*3 000 000 . . . 127 153.7 169 133.2 217 117.6 271 105.2
*2 500 000 . . . 91 165.7 127 140.3 169 121.6 217 107.3
*2 000 000 . . . 91 148.2 127 125.5 169 108.8 217 96.0
1 900 000 . . . 91 144.5 127 122.3 169 106.0 217 93.6
1 800 000 . . . 91 140.6 127 119.1 169 103.2 217 91.1
*1 750 000 . . . 91 138.7 127 117.4 169 101.8 217 89.8
1 700 000 . . . 91 136.7 127 115.7 169 100.3 217 88.5
1 600 000 . . . 91 132.6 127 112.2 169 97.3 217 85.9
*1 500 000 . . . 61 156.8 91 128.4 127 108.7 169 94.2
1 400 000 . . . 61 151.5 91 124.0 127 105.0 169 91.0
1 300 000 . . . 61 146.0 91 119.5 127 101.2 169 87.7
*1 250 000 . . . 61 143.1 91 117.2 127 99.2 169 86.0
1 200 000 . . . 61 140.3 91 114.8 127 97.2 169 84.3
1 100 000 . . . 61 134.3 91 109.9 127 93.1 169 80.7
*1 000 000 . 37 164.4 61 128.0 61 128.0 91 104.8 127 88.7
900 000 . 37 156.0 61 121.5 61 121.5 91 99.4 127 84.2
*800 000 . 37 147.0 61 114.5 61 114.5 91 93.8 127 79.4
*750 000 . 37 142.4 61 110.9 61 110.9 91 90.8 127 76.8
*700 000 . 37 137.5 61 107.1 61 107.1 91 87.7 127 74.2
650 000 . 37 132.5 61 103.2 61 103.2 91 84.5 127 71.5
*600 000 . 37 127.3 37 127.3 61 99.2 91 81.2 127 68.7
550 000 . 37 121.9 37 121.9 61 95.0 91 77.7 127 65.8
*500 000 . 19 162.2 37 116.2 37 116.2 61 90.5 91 74.1
450 000 . 19 153.9 37 110.3 37 110.3 61 85.9 91 70.3
*400 000 . 19 145.1 19 145.1 37 104.0 61 81.0 91 66.3
*350 000 . 12 170.8 19 135.7 37 97.3 61 75.7 91 62.0
*300 000 . 12 158.1 19 125.7 37 90.0 61 70.1 91 57.4
*250 000 . 12 144.3 19 114.7 37 82.2 61 64.0 91 52.4
*211 600 0000 7 173.9 7 173.9 19 105.5 37 75.6 61 58.9
*167 800 000 7 154.8 7 154.8 19 94.0 37 67.3 61 52.4
*133 100 00 7 137.9 7 137.9 19 83.7 37 60.0 61 46.7
*105 600 0 7 122.8 7 122.8 19 74.5 37 53.4 61 41.6
B
*83 690 1 3 167.0 7 109.3 19 66.4 37 47.6 61 37.0
B
*66 360 2 3 148.7 7 97.4 7 97.4 19 59.1 37 42.4
B
*52 620 3 3 132.5 7 86.7 7 86.7 19 52.6 37 37.7
B
*41 740 4 3 118.0 7 77.2 7 77.2 19 46.9 37 33.6
*33 090 5 . . . . 7 68.8 19 41.7 37 29.9
*26 240 6 . . . . 7 61.2 19 37.2 37 26.6
*20 820 7 . . . . 7 54.5 19 33.1 37 23.7
*16 510 8 . . . . 7 48.6 19 29.5 37 21.1
*13 090 9 . . . . 7 43.2 19 26.2 37 18.8
*10 380 10 . . . . 7 38.5 19 23.4 37 16.7
*6 530 12 . . . . 7 30.5 19 18.5 37 13.3
*4 110 14 . . . . 7 24.2 19 14.7 37 10.5
*2 580 16 . . . . 7 19.2 19 11.7 . .
*1 620 18 . . . . 7 15.2 19 9.2 . .
*1 020 20 . . . . 7 12.1 19 7.3 . .
*640 22 . . . . 7 9.6 19 5.8 . .
*404 24 . . . . 7 7.6 19 4.6 . .
* The sizes of conductors that have been marked with an asterisk provide for one or more schedules of preferred series, and are commonly used in the industry. The
sizes not marked are given simply as a matter of reference and it is suggested that their use be discouraged.
A
For unidirectional/unilay constructions the number of wires shown are minimum requirements.
B
Although Class AA conductors having three strands do not conform to the construction requirements of 1.1, they are listed in this table for convenience.
B8 − 23
TABLE 2 Minimum Distance Between Joints in the Completed Conductor
Hard or Medium-Hard Soft
Number of Wires in
Conductor
Class AA Class A Class B Class C Class D All Classes
3 none permitted . . . . 1 ft
7 none permitted 50 ft 50 ft . . 1 ft
12 50 ft 50 ft . . . 1 ft
19 50 ft 50 ft 50 ft 50 ft . 1 ft
A
20 to 36 50 ft 50 ft 50 ft 50 ft . 1 ft in a layer
A
37 to 60 25 ft 25 ft 25 ft 25 ft 1 ft in a layer
A
61 and over . 5 ft 5 ft 5 ft 5 ft 1 ft in a layer
A
Except as indicated, the limitations apply to closeness of joints throughout the completed conductor.
5. Lay 6.2 The diameters of the wires listed in Table 1 are nominal.
Where “combination strand” is required in order to insulate the
5.1 For Class AA conductors composed of less than seven
conductor properly (strands in the outer layer having a larger
wires, the length of lay of a layer of wires shall not be less than
diameter than those in the inner layers) the diameters shall be
8 nor more than 14 times the outside diameter of that layer.
subject to a tolerance of 65 %, provided that the area of cross
5.2 For Class AA conductors composed of seven wires or
section after stranding is in accordance with Section 12.
more, the length of lay of a layer of wires shall not be less than
6.3 Where compressed stranding is required in order to
10 nor more than 16 times the diameter of that layer. The
insulate the conductor properly, one or more layers of any
length of lay of any copper layer shall not be less than the
stranded conductor consisting of 7 wires or more may be
length of lay of the copper layer immediately beneath it.
slightly compressed, thereby reducing the outside diameter of
5.3 For all other classes the lay of a layer of wires shall be
the conductor to the nominal values shown in Table 3, provided
not less than 8 nor more than 16 times the outside diameter of
that the area of cross section after stranding is in accordance
that layer, except that for conductors composed of 37 wires or
with Section 12.
more, this requirement shall apply only to the two outer layers.
The lay of the layers other than the two outer layers shall be at
7. Physical and Electrical Tests of Conductors Stranded
the option of the manufacturer, unless otherwise agreed upon.
of Soft Wires
5.3.1 For conductors to be used in covered or insulated
wires or cables, the lay length shall be not less than 8 nor more 7.1 Tests for the electrical properties of wires composing
than 16 times the outer diameter of the finished conductor. For conductors made from soft or annealed copper wire, bare or
conductors of 37 wires or more, this requirement shall apply to coated, shall be made before stranding.
the wires in the outer two layers. The lay of the layers other
7.2 Tests for the physical properties of soft or annealed
than the two outer layers shall be at the option of the
copper wire, bare or coated, may be made upon the wires
manufacturer, unless otherwise agreed upon.
before stranding or upon wires removed from the complete
5.4 For Class AA and A bare conductors having multiple
stranded conductor, but need not be made upon both. Care shall
layers of copper wires, the length of lay of any copper layer
be taken to avoid mechanical injury to wire removed from the
shall not be less than the length of lay of the copper layer
conductor for the purpose of testing.
immediately beneath it.
7.3 The physical properties of wire when tested before
5.5 Other lays for special purposes shall be furnished by
stranding shall conform to the applicable requirements of 14.2.
special agreement between the manufacturer and the purchaser
7.4 The physical properties of wires removed from the
(Explanatory Note 3).
completed stranded conductor shall be permitted to vary from
5.6 The direction of lay of the outer layer shall be left-hand,
the applicable requirements of 14.2 by the following amounts
and for conductors having a nominal cross-sectional area larger
(Explanatory Note 4):
than No. 8 AWG, shall be reversed in successive layers, unless
7.4.1 Average of Results Obtained on All Wires Tested—The
otherwise specified by the purchaser.
minimum elongation required shall be reduced in numerical
5.6.1 For conductors to be used in covered or insulated
value 5 (for example, from 30 % to 25 %) from the numerical
wires or cables, the direction of lay of the outer layer shall be
requirements for the wire before stranding.
left hand and shall be reversed in successive layers,
7.4.2 Results Obtained on Individual Wires—The elongation
unidirectional, or unilay, unless otherwise agreed upon.
of individual wires shall be reduced in numerical value 15 from
the minimum requirements before stranding (that is, 10 in
6. Construction
addition to the 5 allowed in 7.4.1), but in no case shall the
6.1 The areas of cross section, numbers, and diameters of
elongation of any individual wire be less than 5 %.
wires in the various classes of concentric-lay-stranded conduc-
tors shall conform to the requirements prescribed in Table 1 7.5 In the event that the requirements prescribed in 7.4.2 are
(Explanatory Notes 3 and 9). met but those prescribed in 7.4.1 are not met, a retest shall be
B8 − 23
TABLE 3 Diameters, Areas, and Mass of Concentric-Lay-Stranded Copper Conductors (Explanatory Note 7)
A
Nominal Conductor Diameter, in.
dc Resistance at
Size of Conductor, Mass
B
20 °C
Concentric Strand
Reverse
Concentric
Unilay
Area, in.
Com-
Com-
C
cmil or AWG numbers mm Class AA Class A Class B pressed lbs/1000 ft kg/km Ω/1000 ft Ω/km
pressed
Class B Diameter,
in.
Diameter,
in.
*5 000 000 cmil 2530 . 2.580 2.581 . . 3.927 15 890 23 649 0.00218 0.00715
4 500 000 cmil 2280 . 2.448 2.448 . . 3.534 14 300 21 283 0.00242 0.00794
4 000 000 cmil 2030 . 2.307 2.309 . . 3.142 12 590 18 738 0.00270 0.00886
3 500 000 cmil 1770 . 2.158 2.159 . . 2.749 11 020 16 401 0.00308 0.0101
*3 000 000 cmil 1520 . 1.998 1.998 . . 2.356 9 353 13 920 0.00356 0.0117
*2 500 000 cmil 1270 . 1.823 1.824 . . 1.963 7 794 11 600 0.00427 0.0140
*2 000 000 cmil 1010 . 1.630 1.632 1.583 1.533 1.571 6 175 9 190 0.00529 0.0174
1 900 000 cmil 963 . 1.590 1.590 1.542 1.494 1.492 5 866 8 730 0.00557 0.0183
1 800 000 cmil 912 . 1.547 1.548 1.502 1.454 1.414 5 558 8 272 0.00588 0.0193
*1 750 000 cmil 887 . 1.526 1.526 1.480 1.434 1.374 5 403 8 041 0.00604 0.0198
1 700 000 cmil 861 . 1.504 1.504 1.459 1.413 1.335 5 249 7 812 0.00622 0.0204
1 600 000 cmil 801 . 1.459 1.459 1.415 1.371 1.257 4 940 7 352 0.00661 0.0217
*1 500 000 cmil 760 . 1.411 1.412 1.370 1.327 1.178 4 631 6 892 0.00705 0.0231
1 400 000 cmil 709 . 1.364 1.364 1.323 1.282 1.100 4 323 6 435 0.00756 0.0248
1 300 000 cmil 659 . 1.314 1.315 1.275 1.236 1.021 4 014 5 974 0.00814 0.0267
*1 250 000 cmil 633 . 1.288 1.289 1.250 1.212 0.9817 3 859 5 743 0.00846 0.0278
1 200 000 cmil 608 . 1.263 1.263 1.225 1.187 0.9425 3 705 5 514 0.00882 0.0289
1 100 000 cmil 557 . 1.209 1.209 1.173 1.137 0.8639 3 396 5 054 0.00962 0.0316
*1 000 000 cmil 507 1.151 1.152 1.152 1.117 1.084 0.7854 3 088 4 596 0.0106 0.0348
900 000 cmil 456 1.092 1.094 1.094 1.060 1.028 0.7069 2 779 4 136 0.0118 0.0387
*800 000 cmil 405 1.029 1.031 1.031 1.000 0.969 0.6283 2 470 3 676 0.0132 0.0433
*750 000 cmil 380 0.997 0.998 0.998 0.968 0.939 0.5890 2 316 3 447 0.0141 0.0462
*700 000 cmil 355 0.963 0.964 0.964 0.935 0.907 0.5498 2 161 3 216 0.0151 0.0495
650 000 cmil 329 0.928 0.929 0.929 0.901 0.874 0.5105 2 007 2 987 0.0163 0.0535
*600 000 cmil 304 0.891 0.891 0.893 0.866 0.840 0.4712 1 853 2 758 0.0176 0.0578
550 000 cmil 279 0.853 0.853 0.855 0.829 0.804 0.4320 1 698 2 527 0.0192 0.0630
*500 000 cmil 253 0.811 0.813 0.813 0.789 0.766 0.3927 1 544 2 298 0.0212 0.0695
450 000 cmil 228 0.770 0.772 0.772 0.749 0.727 0.3534 1 389 2 067 0.0235 0.0771
*400 000 cmil 203 0.726 0.726 0.728 0.706 0.685 0.3142 1 235 1 838 0.0264 0.0866
*350 000 cmil 177 0.710 0.679 0.681 0.661 0.641 0.2749 1 081 1 609 0.0302 0.0991
*300 000 cmil 152 0.657 0.629 0.630 0.611 0.594 0.2356 926.3 1 378.6 0.0353 0.116
*250 000 cmil 127 0.600 0.574 0.575 0.558 0.542 0.1963 771.9 1 148.8 0.0423 0.139
* No. 0000 107 0.522 0.522 0.528 0.512 0.498 0.1662 653.1 972.0 0.0500 0.164
* No. 000 85.0 0.464 0.464 0.470 0.456 0.443 0.1318 518.1 771.1 0.0630 0.207
* No. 00 67.4 0.414 0.414 0.419 0.405 0.395 0.1045 410.9 611.5 0.0795 0.261
* No. 0 53.5 0.368 0.368 0.373 0.362 0.352 0.08289 325.8 484.9 0.100 0.328
* No. 1, 3 wire 42.4 0.360 . . . . 0.06573 255.9 380.9 0.126 0.413
* No. 1 42.4 . 0.328 0.332 0.322 0.313 0.06573 258.4 384.6 0.126 0.413
* No. 2, 3 wire 33.6 0.320 . . . . 0.05213 202.9 301.9 0.159 0.522
* No. 2 33.6 . 0.292 0.292 0.283 . 0.05213 204.9 304.9 0.159 0.522
* No. 3, 3 wire 26.7 0.285 . . . . 0.04134 160.9 239.5 0.201 0.659
* No. 3 26.7 . 0.260 0.260 0.252 . 0.04134 162.5 241.9 0.201 0.659
* No. 4, 3 wire 21.2 0.254 . . . . 0.03278 127.6 189.9 0.253 0.830
* No. 4 21.2 . 0.232 0.232 0.225 . 0.03278 128.9 191.8 0.253 0.830
* No. 5 16.8 . . 0.206 0.200 . 0.02600 102.2 152.1 0.319 1.05
* No. 6 13.3 . . 0.184 0.178 . 0.02062 81.05 120.63 0.403 1.32
* No. 7 10.6 . . 0.164 0.159 . 0.01635 64.28 95.67 0.509 1.67
* No. 8 8.37 . . 0.146 0.142 . 0.01297 50.97 75.86 0.640 2.10
* No. 9 6.63 . . 0.130 0.126 . 0.01028 40.42 60.16 0.809 2.65
* No. 10 5.26 . . 0.116 0.113 . 0.008155 32.06 47.72 1.02 3.35
* No. 12 3.31 . . 0.0915 0.089 . 0.005129 20.16 30.00 1.63 5.35
* No. 14 2.08 . . 0.0726 0.071 . 0.003225 12.68 18.87 2.58 8.46
* No. 16 0.823 . . 0.0576 . . 0.002028 7.974 11.868 4.10 13.45
* No. 18 0.51
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: B8 − 11 (Reapproved 2017) B8 − 23
Standard Specification for
Concentric-Lay-Stranded Copper Conductors, Hard,
Medium-Hard, or Soft
This standard is issued under the fixed designation B8; 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 (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope
1.1 This specification covers bare concentric-lay-stranded conductors made from round copper wires, either uncoated or coated
with tin, lead, or lead alloy for general use for electrical purposes. These conductors shall be constructed with a central core
surrounded by one or more layers of helically laid wires.
NOTE 1—This specification also permits conductors for use as covered or insulated electrical conductors.
NOTE 2—Sealed conductors, that are intended to prevent longitudinal water propagation and are further covered/insulated, are also permitted within the
guidelines of this specification.
1.2 For the purposes of this specification, conductors are classified as follows (Explanatory Note 1 and Note 2):
1.2.1 Class AA—For bare conductors usually used in overhead lines.
1.2.2 Class A—For conductors to be covered with weather-resistant (weather-proof), slow-burning materials, and for bare
conductors where greater flexibility than is afforded by Class AA is required.
1.2.3 Class B—For conductors to be insulated with various materials such as rubber, paper, varnished cloth, and so forth, and for
the conductors indicated under Class A where greater flexibility is required.
1.2.4 Class C and Class D—For conductors where greater flexibility is required than is provided by Class B conductors.
1.3 The SI values for density are regarded as the standard. For all other properties, the inch-pound values are to be regarded as
standard and the SI units may be approximate.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
This specification is under the jurisdiction of ASTM Committee B01 on Electrical Conductors and is the direct responsibility of Subcommittee B01.04 on Conductors
of Copper and Copper Alloys.
Current edition approved April 1, 2017Nov. 1, 2023. Published April 2017November 2023. Originally approved in 1915. Last previous edition approved in 20112017 as
B8 – 11.B8 – 11 (2017). DOI: 10.1520/B0008-11R17.10.1520/B0008-23.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B8 − 23
2. Referenced Documents
2.1 ASTM Standards:
B1 Specification for Hard-Drawn Copper Wire
B2 Specification for Medium-Hard-Drawn Copper Wire
B3 Specification for Soft or Annealed Copper Wire
B33 Specification for Tin-Coated Soft or Annealed Copper Wire for Electrical Purposes
B172 Specification for Rope-Lay-Stranded Copper Conductors Having Bunch-Stranded Members, for Electrical Conductors
B173 Specification for Rope-Lay-Stranded Copper Conductors Having Concentric-Stranded Members, for Electrical Conduc-
tors
B174 Specification for Bunch-Stranded Copper Conductors for Electrical Conductors
B189 Specification for Lead-Coated and Lead-Alloy-Coated Soft Copper Wire for Electrical Purposes
B193 Test Method for Resistivity of Electrical Conductor Materials
B246 Specification for Tinned Hard-Drawn and Medium-Hard-Drawn Copper Wire for Electrical Purposes
B263 Test Method for Determination of Cross-Sectional Area of Stranded Conductors
B354 Terminology Relating to Uninsulated Metallic Electrical Conductors
B787/B787M Specification for 19 Wire Combination Unilay-Stranded Copper Conductors for Subsequent Insulation
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
3. Ordering Information
3.1 Orders for material under this specification shall include the following information:
3.1.1 Quantity of each size and class,
3.1.2 Conductor size: circular-mil area or AWG (Section 6),
3.1.3 Class (see 1.2 and Table 1),
3.1.4 Temper (see 13.214.2),
3.1.5 Whether coated or uncoated; if coated, designate type of coating (see 13.114.1 and 13.214.2),
3.1.6 Details of special-purpose lays, if required (see 5.45.5),
3.1.7 When physical tests shall be made (see Sections 7 and 89),
3.1.8 Package size (see Section 1516),
3.1.9 Lagging, if required (see section 15.216.2),
3.1.10 Special package marking, if required (see section 15.316.3), and
3.1.11 Place of inspection (see Section 1415).
4. Joints
4.1 Welds and brazes may be made in rods or in wires prior to final drawing. Joints may not be made in the finished wires
composing hard-drawn or medium-hard-drawn Class AA conductors of seven wires or less. In other conductors, welds and brazes
may be made in the finished individual wires composing the conductor, but shall not be closer together than prescribed in Table
2.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
B8 − 23
TABLE 1 Construction Requirements of Concentric-Lay-Stranded Copper Conductors
A
Area of Size,
Class AA Class A Class B Class C Class D
Cross-Section, American
Number of Diameter of Number of Diameter of Number of Diameter of Number of Diameter of Number of Diameter of
cmil Wire
Wires Wires, mils Wires Wires, mils Wires Wires, mils Wires Wires, mils Wires Wires, mils
GageGauge
*5 000 000 . . . 169 172.0 217 151.8 271 135.8 271 135.8
4 500 000 . . . 169 163.2 217 144.0 271 128.9 271 128.9
4 000 000 . . . 169 153.8 217 135.8 271 121.5 271 121.5
3 500 000 . . . 127 166.0 169 143.9 217 127.0 271 113.6
*3 000 000 . . . 127 153.7 169 133.2 217 117.6 271 105.2
*2 500 000 . . . 91 165.7 127 140.3 169 121.6 217 107.3
*2 000 000 . . . 91 148.2 127 125.5 169 108.8 217 96.0
1 900 000 . . . 91 144.5 127 122.3 169 106.0 217 93.6
1 800 000 . . . 91 140.6 127 119.1 169 103.2 217 91.1
*1 750 000 . . . 91 138.7 127 117.4 169 101.8 217 89.8
1 700 000 . . . 91 136.7 127 115.7 169 100.3 217 88.5
1 600 000 . . . 91 132.6 127 112.2 169 97.3 217 85.9
*1 500 000 . . . 61 156.8 91 128.4 127 108.7 169 94.2
1 400 000 . . . 61 151.5 91 124.0 127 105.0 169 91.0
1 300 000 . . . 61 146.0 91 119.5 127 101.2 169 87.7
*1 250 000 . . . 61 143.1 91 117.2 127 99.2 169 86.0
1 200 000 . . . 61 140.3 91 114.8 127 97.2 169 84.3
1 100 000 . . . 61 134.3 91 109.9 127 93.1 169 80.7
*1 000 000 . 37 164.4 61 128.0 61 128.0 91 104.8 127 88.7
900 000 . 37 156.0 61 121.5 61 121.5 91 99.4 127 84.2
*800 000 . 37 147.0 61 114.5 61 114.5 91 93.8 127 79.4
*750 000 . 37 142.4 61 110.9 61 110.9 91 90.8 127 76.8
*700 000 . 37 137.5 61 107.1 61 107.1 91 87.7 127 74.2
650 000 . 37 132.5 61 103.2 61 103.2 91 84.5 127 71.5
*600 000 . 37 127.3 37 127.3 61 99.2 91 81.2 127 68.7
550 000 . 37 121.9 37 121.9 61 95.0 91 77.7 127 65.8
*500 000 . 19 162.2 37 116.2 37 116.2 61 90.5 91 74.1
450 000 . 19 153.9 37 110.3 37 110.3 61 85.9 91 70.3
*400 000 . 19 145.1 19 145.1 37 104.0 61 81.0 91 66.3
*350 000 . 12 170.8 19 135.7 37 97.3 61 75.7 91 62.0
*300 000 . 12 158.1 19 125.7 37 90.0 61 70.1 91 57.4
*250 000 . 12 144.3 19 114.7 37 82.2 61 64.0 91 52.4
*211 600 0000 7 173.9 7 173.9 19 105.5 37 75.6 61 58.9
*167 800 000 7 154.8 7 154.8 19 94.0 37 67.3 61 52.4
*133 100 00 7 137.9 7 137.9 19 83.7 37 60.0 61 46.7
*105 600 0 7 122.8 7 122.8 19 74.5 37 53.4 61 41.6
B
*83 690 1 3 167.0 7 109.3 19 66.4 37 47.6 61 37.0
B
*66 360 2 3 148.7 7 97.4 7 97.4 19 59.1 37 42.4
B
*52 620 3 3 132.5 7 86.7 7 86.7 19 52.6 37 37.7
B
*41 740 4 3 118.0 7 77.2 7 77.2 19 46.9 37 33.6
*33 090 5 . . . . 7 68.8 19 41.7 37 29.9
*26 240 6 . . . . 7 61.2 19 37.2 37 26.6
*20 820 7 . . . . 7 54.5 19 33.1 37 23.7
*16 510 8 . . . . 7 48.6 19 29.5 37 21.1
*13 090 9 . . . . 7 43.2 19 26.2 37 18.8
*10 380 10 . . . . 7 38.5 19 23.4 37 16.7
*6 530 12 . . . . 7 30.5 19 18.5 37 13.3
*4 110 14 . . . . 7 24.2 19 14.7 37 10.5
*2 580 16 . . . . 7 19.2 19 11.7 . .
*1 620 18 . . . . 7 15.2 19 9.2 . .
*1 020 20 . . . . 7 12.1 19 7.3 . .
*640 22 . . . . 7 9.6 19 5.8 . .
*404 24 . . . . 7 7.6 19 4.6 . .
* The sizes of conductors that have been marked with an asterisk provide for one or more schedules of preferred series, and are commonly used in the industry. The
sizes not marked are given simply as a matter of reference and it is suggested that their use be discouraged.
A
For unidirectional/unilay constructions the number of wires shown are minimum requirements.
B
Although Class AA conductors having three strands do not conform to the construction requirements of 1.1, they are listed in this table for convenience.
5. Lay
5.1 For Class AA conductors composed of less than seven wires, the preferred lay is 11 times the outside diameter of the completed
conductor, but shall be not length of lay of a layer of wires shall not be less than 8 nor more than 14 times this diameter.the
outside diameter of that layer.
5.2 For Class AA conductors composed of seven wires or more, the preferred length of lay of a layer of wires is 13.5 times the
B8 − 23
TABLE 2 Minimum Distance Between Joints in the Completed Conductor
Hard or Medium-Hard Soft
Number of Wires in
Conductor
Class AA Class A Class B Class C Class D All Classes
3 none permitted . . . . 1 ft
7 none permitted 50 ft 50 ft . . 1 ft
12 50 ft 50 ft . . . 1 ft
19 50 ft 50 ft 50 ft 50 ft . 1 ft
A
20 to 36 50 ft 50 ft 50 ft 50 ft . 1 ft in a layer
A
37 to 60 25 ft 25 ft 25 ft 25 ft 1 ft in a layer
A
61 and over . 5 ft 5 ft 5 ft 5 ft 1 ft in a layer
A
Except as indicated, the limitations apply to closeness of joints throughout the completed conductor.
outside diameter of that layer, but shall be not less than 10 nor more than 16 times this diameter.shall not be less than 10 nor more
than 16 times the diameter of that layer. The length of lay of any copper layer shall not be less than the length of lay of the copper
layer immediately beneath it.
5.3 For all other classes the lay of a layer of wires shall be not less than 8 nor more than 16 times the outside diameter of that
layer, except that for conductors composed of 37 wires or more, this requirement shall apply only to the two outer layers. The lay
of the layers other than the two outer layers shall be at the option of the manufacturer, unless otherwise agreed upon.
5.3.1 For conductors to be used in covered or insulated wires or cables, the lay length shall be not less than 8 nor more than 16
times the outer diameter of the finished conductor. For conductors of 37 wires or more, this requirement shall apply to the wires
in the outer two layers. The lay of the layers other than the two outer layers shall be at the option of the manufacturer, unless
otherwise agreed upon.
5.4 For Class AA and A bare conductors having multiple layers of copper wires, the length of lay of any copper layer shall not
be less than the length of lay of the copper layer immediately beneath it.
5.5 Other lays for special purposes shall be furnished by special agreement between the manufacturer and the purchaser
(Explanatory Note 3).
5.6 The direction of lay of the outer layer shall be left-hand, and for conductors having a nominal cross-sectional area larger than
No. 8 AWG, shall be reversed in successive layers, unless otherwise specified by the purchaser.
5.6.1 For conductors to be used in covered or insulated wires or cables, the direction of lay of the outer layer shall be left hand
and shall be reversed in successive layers, unidirectional, or unilay, unless otherwise agreed upon.
6. Construction
6.1 The areas of cross section, numbers, and diameters of wires in the various classes of concentric-lay-stranded conductors shall
conform to the requirements prescribed in Table 1 (Explanatory Notes 3 and 109).
6.2 The diameters of the wires listed in Table 1 are nominal. Where “combination strand” is required in order to insulate the
conductor properly (strands in the outer layer having a larger diameter than those in the inner layers) the diameters shall be subject
to a tolerance of 65 %, provided that the area of cross section after stranding is in accordance with Section 1112.
6.3 Where compressed stranding is required in order to insulate the conductor properly, one or more layers of any stranded
conductor consisting of 7 wires or more may be slightly compressed, thereby reducing the outside diameter of the conductor to
the nominal values shown in Table 3, provided that the area of cross section after stranding is in accordance with Section 1112.
7. Physical and Electrical Tests of Conductors Stranded of Soft Wires
7.1 Tests for the electrical properties of wires composing conductors made from soft or annealed copper wire, bare or coated, shall
be made before stranding.
7.2 Tests for the physical properties of soft or annealed copper wire, bare or coated, may be made upon the wires before stranding
B8 − 23
TABLE 3 Diameters, Areas, and Mass of Concentric-Lay-Stranded Copper Conductors (Explanatory Note 87)
A
Nominal Conductor Diameter, in.
dc Resistance at
Size of Conductor, Mass
B
20°C20 °C
Concentric Strand
Reverse
Concentric
Unilay
Area, in.
Com-
Com-
C
cmil or AWG numbers mm Class AA Class A Class B pressed lbs/1000 ft kg/km Ω/1000 ft Ω/km
pressed
Class B Diameter,
in.
Diameter,
in.
*5 000 000 cmil 2530 . 2.580 2.581 . . 3.927 15 890 23 649 0.00218 0.00715
4 500 000 cmil 2280 . 2.448 2.448 . . 3.534 14 300 21 283 0.00242 0.00794
4 000 000 cmil 2030 . 2.307 2.309 . . 3.142 12 590 18 738 0.00270 0.00886
3 500 000 cmil 1770 . 2.158 2.159 . . 2.749 11 020 16 401 0.00308 0.0101
*3 000 000 cmil 1520 . 1.998 1.998 . . 2.356 9 353 13 920 0.00356 0.0117
*2 500 000 cmil 1270 . 1.823 1.824 . . 1.963 7 794 11 600 0.00427 0.0140
*2 000 000 cmil 1010 . 1.630 1.632 1.583 1.533 1.571 6 175 9 190 0.00529 0.0174
1 900 000 cmil 963 . 1.590 1.590 1.542 1.494 1.492 5 866 8 730 0.00557 0.0183
1 800 000 cmil 912 . 1.547 1.548 1.502 1.454 1.414 5 558 8 272 0.00588 0.0193
*1 750 000 cmil 887 . 1.526 1.526 1.480 1.434 1.374 5 403 8 041 0.00604 0.0198
1 700 000 cmil 861 . 1.504 1.504 1.459 1.413 1.335 5 249 7 812 0.00622 0.0204
1 600 000 cmil 801 . 1.459 1.459 1.415 1.371 1.257 4 940 7 352 0.00661 0.0217
*1 500 000 cmil 760 . 1.411 1.412 1.370 1.327 1.178 4 631 6 892 0.00705 0.0231
1 400 000 cmil 709 . 1.364 1.364 1.323 1.282 1.100 4 323 6 435 0.00756 0.0248
1 300 000 cmil 659 . 1.314 1.315 1.275 1.236 1.021 4 014 5 974 0.00814 0.0267
*1 250 000 cmil 633 . 1.288 1.289 1.250 1.212 0.9817 3 859 5 743 0.00846 0.0278
1 200 000 cmil 608 . 1.263 1.263 1.225 1.187 0.9425 3 705 5 514 0.00882 0.0289
1 100 000 cmil 557 . 1.209 1.209 1.173 1.137 0.8639 3 396 5 054 0.00962 0.0316
*1 000 000 cmil 507 1.151 1.152 1.152 1.117 1.084 0.7854 3 088 4 596 0.0106 0.0348
900 000 cmil 456 1.092 1.094 1.094 1.060 1.028 0.7069 2 779 4 136 0.0118 0.0387
*800 000 cmil 405 1.029 1.031 1.031 1.000 0.969 0.6283 2 470 3 676 0.0132 0.0433
*750 000 cmil 380 0.997 0.998 0.998 0.968 0.939 0.5890 2 316 3 447 0.0141 0.0462
*700 000 cmil 355 0.963 0.964 0.964 0.935 0.907 0.5498 2 161 3 216 0.0151 0.0495
650 000 cmil 329 0.928 0.929 0.929 0.901 0.874 0.5105 2 007 2 987 0.0163 0.0535
*600 000 cmil 304 0.891 0.891 0.893 0.866 0.840 0.4712 1 853 2 758 0.0176 0.0578
550 000 cmil 279 0.853 0.853 0.855 0.829 0.804 0.4320 1 698 2 527 0.0192 0.0630
*500 000 cmil 253 0.811 0.813 0.813 0.789 0.766 0.3927 1 544 2 298 0.0212 0.0695
450 000 cmil 228 0.770 0.772 0.772 0.749 0.727 0.3534 1 389 2 067 0.0235 0.0771
*400 000 cmil 203 0.726 0.726 0.728 0.706 0.685 0.3142 1 235 1 838 0.0264 0.0866
*350 000 cmil 177 0.710 0.679 0.681 0.661 0.641 0.2749 1 081 1 609 0.0302 0.0991
*300 000 cmil 152 0.657 0.629 0.630 0.611 0.594 0.2356 926.3 1 378.6 0.0353 0.116
*250 000 cmil 127 0.600 0.574 0.575 0.558 0.542 0.1963 771.9 1 148.8 0.0423 0.139
* No. 0000 107 0.522 0.522 0.528 0.512 0.498 0.1662 653.1 972.0 0.0500 0.164
* No. 000 85.0 0.464 0.464 0.470 0.456 0.443 0.1318 518.1 771.1 0.0630 0.207
* No. 00 67.4 0.414 0.414 0.419 0.405 0.395 0.1045 410.9 611.5 0.0795 0.261
* No. 0 53.5 0.368 0.368 0.373 0.362 0.352 0.08289 325.8 484.9 0.100 0.328
* No. 1, 3 wire 42.4 0.360 . . . . 0.06573 255.9 380.9 0.126 0.413
* No. 1 42.4 . 0.328 0.332 0.322 0.313 0.06573 258.4 384.6 0.126 0.413
* No. 2, 3 wire 33.6 0.320 . . . . 0.05213 202.9 301.9 0.159 0.522
* No. 2 33.6 . 0.292 0.292 0.283 . 0.05213 204.9 304.9 0.159 0.522
* No. 3, 3 wire 26.7 0.285 . . . . 0.04134 160.9 239.5 0.201 0.659
* No. 3 26.7 . 0.260 0.260 0.252 . 0.04134 162.5 241.9 0.201 0.659
* No. 4, 3 wire 21.2 0.254 . . . . 0.03278 127.6 189.9 0.253 0.830
* No. 4 21.2 . 0.232 0.232 0.225 . 0.03278 128.9 191.8 0.253 0.830
* No. 5 16.8 . . 0.206 0.200 . 0.02600 102.2 152.1 0.319 1.05
* No. 6 13.3 . . 0.184 0.178 . 0.02062 81.05 120.63 0.403 1.32
* No. 7 10.6 . . 0.164 0.159 . 0.01635 64.28 95.67 0.509 1.67
* No. 8 8.37 . . 0.146 0.142 . 0.01297 50.97 75.86 0.640 2.10
* No. 9 6.63 . . 0.130 0.126 . 0.01028 40.42 60.16 0.809 2.65
* No. 10 5.26 . . 0.116 0.113 . 0.008155 32.06 47.72 1.02 3.35
* No. 12 3.31 . . 0.0915 0.089 . 0.005129 20.16 30.00 1.63 5.35
* No. 14 2.08 . . 0.0726 0.071 . 0.003225 12.68 18.87 2.58 8.46
* No. 16 0.823 . . 0.0576 . . 0.002028 7.974 11.868 4.10 13.45
* No. 18 0.519 . . 0.0456 . . 0.001276 5.015 7.464 6.54 21.46
* No. 20 0.519 . . 0.0363 . . 0.0008023 3.154 4.694 10.3 33.8
* No. 22 0.324 . . 0.0288 . . 0.0005067 1.992 2.965 16.4 53.8
* No. 24 0.205 . . 0.0228 . . 0.0003176 1.249 1.859 26.1 85.6
* The sizes of conductors which have been marked with a single asterisk provide for one or more schedules of preferred series, and are commonly used in the in-
dustry. The sizes not marked are given simply as a matter of reference, and it is suggested that their use be discouraged.
A
To calculate the nominal diameters of Class C or Class D conductors or of any concentric-lay-stranded conductors made from round wires of uniform diameters, multiply
the diameter of an individual wire (as given in Table 1) by that one of the following factors which applies:
B
Resistances (dc) apply to Class B, C, and D stranding. For other classes of stranding, refer to Test Method B193. Resistance (dc) based on annealed copper.
C
For conductors manufactured for subsequent covering or insulating.
Number of Wires in Conductor Factor to Calculate
Conductor Diameter
B8 − 23
3 2.155
7 3
12 4.155
19 5
37 7
61 9
91 11
127 13
169 15
217 17
271 19
or upon wires removed from the complete stranded conductor, but need not be made upon both. Care shall be taken to avoid
mechanical injury to wire removed from the conductor for the purpose of testing.
7.3 The physical properties of wire when tested before stranding shall conform to the applicable requirements of 13.214.2.
7.4 The physical properties of wires removed from the completed stranded conductor shall be permitted to vary from the
applicable requirements of 13.214.2 by the following amounts (Explanatory Note 4):
7.4.1 Average of Results Obtained on All Wires Tested—The minimum elongation required shall be reduced in numerical value
5 (for example, from 3030 % to 25 %) from the numerical requirements for the wire before stranding.
7.4.2 Results Obtained on Individual Wires—The elongation of individual wires shall
...