ASTM B173-17

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: B173 − 10 (Reapproved 2015) B173 − 17
Standard Specification for
Rope-Lay-Stranded Copper Conductors Having Concentric-
Stranded Members, for Electrical Conductors
This standard is issued under the fixed designation B173; 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 rope-lay-stranded conductors having concentric-stranded members made from round copper
wires, either uncoated or coated with tin, lead, or lead-alloy for use as electrical conductors (Explanatory Note 1 and Note 2).
1.2 Coated wires shall include only those wires with finished diameters and densities substantially equal to the respective
diameters and densities of uncoated wires.
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.
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.
2. Referenced Documents
2.1 The following documents of the issue in effect at the time of reference form a part of this specification to the extent
referenced herein:
2.2 ASTM Standards:
B3 Specification for Soft or Annealed Copper Wire
B8 Specification for Concentric-Lay-Stranded Copper Conductors, Hard, Medium-Hard, or Soft
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
B189 Specification for Lead-Coated and Lead-Alloy-Coated Soft Copper Wire for Electrical Purposes
B193 Test Method for Resistivity of Electrical Conductor Materials
B263 Test Method for Determination of Cross-Sectional Area of Stranded Conductors
B354 Terminology Relating to Uninsulated Metallic Electrical Conductors
2.3 American National Standard:
ANSI C42.35 Definitions of Electrical Terms
3. Classification
3.1 For the purpose of this specification rope-lay-stranded conductors having concentric-stranded members are classified as
follows:
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, 2015April 1, 2017. Published April 2015April 2017. Originally approved in 1942 to replace portions of B158 – 41 T. Last previous
edition approved in 20102015 as B173 – 10.B173 – 10 (2015). DOI: 10.1520/B0173-10R15.10.1520/B0173-17.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B173 − 17
3.1.1 Class G—Conductors consisting of 7 to 61 rope-lay-stranded members, each of which consists of 7 to 19 concentric-
2 2
stranded wires, with total conductor sizes ranging from No. 14 AWG (2.08 mm ) to 5 000 000 cmil (2534 mm ). (Typical use is
for rubber-sheathed conductor, apparatus conductor, portable conductor, and similar applications.)
3.1.2 Class H—Conductors consisting of 19 to 91 rope-lay-stranded members, each of which consists of 7 to 19
2 2
concentric-stranded wires, with total conductor sizes ranging from No. 9 AWG (6.63 mm ) to 5 000 000 cmil (2534 mm ). Class
K construction produces a conductor with greater flexibility than class G. (Typical use is for rubber-sheathed cord and applications
where flexibility is required such as on take-up reels over sheaves and extra-flexible apparatus conductor.)
4. Ordering Information
4.1 Orders for material under this specification shall include the following information:
4.1.1 Quantity of each size and class;
4.1.2 Conductor size: circular-mil area or AWG (Section 7);
4.1.3 Class (Section 3 and Tables 1 and 2);
4.1.4 Whether coated or uncoated; if coated, designate type of coating (see 11.1);
4.1.5 Details of special-purpose lays, if required (see 6.2 and 6.3) and (Explanatory Note 3);
4.1.6 Package size (see 14.1);
4.1.7 Special package marking, if required (Section 15);
4.1.8 Lagging, if required (see 14.2); and
4.1.9 Place of inspection (Section 13).
5. Joints
5.1 Necessary joints in wires or in groups of wires shall be made in accordance with accepted commercial practice, taking into
account the size of the wire or group of wires as related to the size of the entire conductor.
5.2 Concentric-stranded members forming the completed conductor may be joined as a unit by soldering, brazing, or welding.
5.3 Joints shall be so constructed and so disposed throughout the conductor that the diameter or configuration of the completed
conductor is not substantially affected, and so that the flexibility of the completed conductor is not adversely affected.
6. Lay (Explanatory Note 3)
6.1 Conductors of the same size and description furnished on one order shall have the same lay.
6.2 The length of lay of the outer layer of the rope-lay stranded conductor shall be not less than 8 nor more than 16 times the
outside diameter of the completed conductor. The length of lay of the other layers shall be at the option of the manufacturer unless
specifically agreed upon. The direction of lay of the outer layer shall be left-hand, unless the direction of lay is specified otherwise
by the purchaser. The direction of lay of the other layers shall be reversed in successive layers, unless otherwise agreed upon
between the manufacturer and the purchaser.
6.3 The length of lay of the individual wires composing the stranded members shall be not less than 8 nor more than 16 times
the outside diameter of that layer. Unless otherwise specified, the direction of lay of the outer layer of wires shall be at the option
of the manufacturer. The direction of lay shall be reversed in successive layers, unless otherwise agreed upon between the
manufacturer and the purchaser.
7. Construction
7.1 The area of cross section and the number and diameter of wires for a variety of strand constructions in general use are shown
in Tables 1 and 2.
8. Physical and Electrical Tests
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.
8.2 Tests for the physical properties of soft or annealed copper wire, bare or coated, may be made upon the wires before
stranding or upon wires removed from the completed stranded conductors, but need not be made upon both. Care shall be taken
to avoid mechanical injury and stretching when removing wires from the conductor for the purpose of testing.
8.3 The physical properties of wire when tested before stranding shall conform to the applicable requirements of 11.1.
8.4 The physical properties of wires removed from the completed stranded conductor shall be permitted to vary from the
applicable requirements of 11.1 by the following amounts: (Explanatory Note 4):
8.4.1 Average of Results Obtained on All Wires Tested—The percent minimum elongation may be reduced by the value of 5 %
from the values required for unstranded wires as specified by Specifications B3, B33, or B189, as applicable. For example, where
the unstranded wire specification requires minimum elongation of 30 %, wire of that material removed from Specification B173
stranded conductor shall meet a minimum elongation value of 25 %, a value 5 % reduction.
B173 − 17
A
TABLE 1 Constructional and DC Resistance Requirements of Rope-Lay Stranded Copper Conductors Having Concentric-Stranded Members—Class G
B
Completed Conductor Uncoated Copper Tinned Copper
Area of Cross
Diameter Nominal DC
Nominal Nominal Maximum DC Nominal DC Maximum DC
Number
Section
of Resistance
Size Diameter Mass Resistance @20C Resistance @20C Resistance @20C
Number of
Wires @20C
AWG
of Wires
lb/
Wires in Each
ohm/ ohm/ ohm/ ohm/
cmil mm in. mm in. mm 1000 kg/km ohm/km ohm/km ohm/km ohm/km
Member
1000 ft 1000 ft 1000 ft 1000 ft
ft
5 000 000 2534 . . . 1159 0.0657 1.67 19 2.957 75.1 16 052 23 888 0.00220 0.00721 0.00224 0.00735 0.00229 0.00750 0.00234 0.00765
4 500 000 2280 . . . 1159 0.0623 1.58 19 2.804 71.2 14 433 21 479 0.00244 0.00801 0.00249 0.00817 0.00254 0.00833 0.00259 0.00850
4 000 000 2027 . . . 1159 0.0587 1.49 19 2.642 67.1 12 814 19 069 0.00275 0.00902 0.00281 0.00920 0.00286 0.00938 0.00292 0.00957
3 500 000 1773 . . . 1159 0.0550 1.40 19 2.475 62.9 11 249 16 741 0.00314 0.0103 0.00320 0.0105 0.00327 0.0107 0.00334 0.0109
3 000 000 1520 . . . 1159 0.0509 1.29 19 2.291 58.2 9635 14 338 0.00366 0.0120 0.00373 0.0122 0.00381 0.0125 0.00389 0.0128
2 500 000 1267 . . . 703 0.0596 1.51 19 2.086 53.0 8012 11 924 0.00440 0.0144 0.00449 0.0147 0.00457 0.0150 0.00466 0.0153
2 000 000 1013 . . . 703 0.0533 1.35 19 1.866 47.4 6408 9536 0.00550 0.0180 0.00561 0.0184 0.00572 0.0188 0.00583 0.0192
1 900 000 963 . . . 703 0.0520 1.32 19 1.820 46.2 6099 9077 0.00579 0.0190 0.00591 0.0194 0.00602 0.0197 0.00614 0.0201
1 800 000 912 . . . 703 0.0506 1.29 19 1.771 45.0 5775 8594 0.00611 0.0200 0.00623 0.0204 0.00635 0.0208 0.00648 0.0212
1 750 000 887 . . . 703 0.0499 1.27 19 1.747 44.4 5617 8358 0.00628 0.0206 0.00641 0.0210 0.00653 0.0214 0.00666 0.0218
1 700 000 861 . . . 703 0.0492 1.25 19 1.722 43.7 5460 8125 0.00647 0.0212 0.00660 0.0216 0.00672 0.0221 0.00685 0.0225
1 600 000 811 . . . 703 0.0477 1.21 19 1.670 42.4 5132 7638 0.00687 0.0225 0.00701 0.0230 0.00715 0.0234 0.00729 0.0239
1 500 000 760 . . . 427 0.0593 1.51 7 1.601 40.7 4772 7102 0.00726 0.0238 0.00741 0.0243 0.00755 0.0248 0.00770 0.0253
1 400 000 709 . . . 427 0.0573 1.46 7 1.547 39.3 4456 6631 0.00778 0.0255 0.00794 0.0260 0.00809 0.0265 0.00825 0.0270
1 300 000 659 . . . 427 0.0552 1.40 7 1.490 37.8 4135 6154 0.00838 0.0275 0.00855 0.0281 0.00871 0.0286 0.00888 0.0292
1 250 000 633 . . . 427 0.0541 1.37 7 1.461 37.1 3972 5911 0.00871 0.0286 0.00888 0.0292 0.00906 0.0297 0.00924 0.0303
1 200 000 608 . . . 427 0.0530 1.35 7 1.431 36.3 3812 5673 0.00907 0.0298 0.00925 0.0304 0.00944 0.0310 0.00963 0.0316
1 100 000 557 . . . 427 0.0508 1.29 7 1.372 34.8 3502 5212 0.00990 0.0325 0.0101 0.0332 0.0103 0.0338 0.0105 0.0345
1 000 000 507 . . . 427 0.0484 1.23 7 1.307 33.2 3179 4731 0.01090 0.0357 0.0111 0.0364 0.0113 0.0372 0.0115 0.0379
900 000 456 . . . 427 0.0459 1.17 7 1.239 31.5 2859 4255 0.0121 0.0397 0.0123 0.0405 0.0126 0.0413 0.0129 0.0421
800 000 405 . . . 427 0.0433 1.10 7 1.169 29.7 2544 3787 0.0136 0.0447 0.0139 0.0456 0.0142 0.0464 0.0145 0.0473
750 000 380 . . . 427 0.0419 1.06 7 1.131 28.7 2383 3546 0.0145 0.0476 0.0148 0.0486 0.0151 0.0495 0.0154 0.0505
700 000 355 . . . 427 0.0405 1.03 7 1.094 27.8 2226 3313 0.0156 0.0510 0.0159 0.0520 0.0162 0.0531 0.0165 0.0542
650 000 329 . . . 427 0.0390 0.99 7 1.053 26.7 2064 3072 0.0168 0.0550 0.0171 0.0561 0.0174 0.0572 0.0177 0.0583
600 000 304 . . . 427 0.0375 0.95 7 1.013 25.7 1908 2840 0.0181 0.0595 0.0185 0.0607 0.0189 0.0619 0.0193 0.0631
550 000 279 . . . 427 0.0359 0.91 7 0.969 24.6 1749 2603 0.0198 0.0650 0.0202 0.0663 0.0206 0.0676 0.0210 0.0690
500 000 253 . . . 259 0.0439 1.12 7 0.922 23.4 1579 2350 0.0217 0.0711 0.0221 0.0725 0.0225 0.0740 0.0230 0.0755
450 000 228 . . . 259 0.0417 1.06 7 0.876 22.3 1425 2120 0.0241 0.0790 0.0246 0.0806 0.0251 0.0822 0.0255 0.0838
400 000 203 . . . 259 0.0393 1.00 7 0.825 21.0 1265 1883 0.0271 0.0889 0.0276 0.0907 0.0282 0.0924 0.0288 0.0942
350 000 177 . . . 259 0.0368 0.93 7 0.773 19.6 1109 1651 0.0310 0.102 0.0316 0.104 0.0322 0.106 0.0328 0.108
300 000 152 . . . 259 0.0340 0.86 7 0.714 18.1 947 1409 0.0361 0.119 0.0368 0.121 0.0376 0.123 0.0384 0.125
250 000 127 . . . 259 0.0311 0.79 7 0.653 16.6 792 1179 0.0434 0.142 0.0443 0.145 0.0451 0.148 0.0460 0.151
211 600 107 0000 133 0.0399 1.01 7 0.599 15.2 667 992 0.0510 0.167 0.0520 0.170 0.0530 0.174 0.0541 0.177
167 800 85.0 000 133 0.0355 0.90 7 0.533 13.5 528 785 0.0643 0.211 0.0656 0.215 0.0668 0.219 0.0681 0.223
133 100 67.4 00 133 0.0316 0.80 7 0.474 12.0 418 622 0.0810 0.266 0.0826 0.271 0.0843 0.276 0.0860 0.282
105 600 53.5 0 133 0.0282 0.72 7 0.423 10.7 333 495 0.102 0.335 0.104 0.342 0.106 0.348 0.108 0.355
83 690 42.4 1 133 0.0251 0.64 7 0.377 9.6 264 393 0.129 0.423 0.132 0.431 0.134 0.440 0.137 0.449
66 360 33.6 2 49 0.0368 0.93 7 0.331 8.4 207 308 0.161 0.528 0.164 0.539 0.167 0.549 0.170 0.560
52 620 26.7 3 49 0.0328 0.83 7 0.295 7.5 164 245 0.203 0.666 0.207 0.679 0.211 0.693 0.215 0.707
41 740 21.1 4 49 0.0292 0.74 7 0.263 6.7 130 194 0.256 0.840 0.261 0.857 0.266 0.873 0.271 0.890
33 090 16.8 5 49 0.0260 0.66 7 0.234 5.9 103 154 0.323 1.06 0.329 1.08 0.336 1.10 0.343 1.12
26 240 13.3 6 49 0.0231 0.59 7 0.208 5.3 81.5 121 0.407 1.34 0.415 1.37 0.423 1.39 0.431 1.42
20 820 10.5 7 49 0.0206 0.52 7 0.185 4.7 64.8 96.5 0.513 1.68 0.523 1.71 0.534 1.75 0.545 1.79
16 510 8.37 8 49 0.0184 0.47 7 0.166 4.2 51.7 77.0 0.647 2.12 0.660 2.16 0.687 2.25 0.701 2.30
13 090 6.63 9 49 0.0163 0.41 7 0.148 3.8 40.6 60.4 0.816 2.68 0.832 2.73 0.867 2.84 0.884 2.90
10 380 5.26 10 49 0.0146 0.37 7 0.131 3.3 32.6 48.5 1.03 3.38 1.05 3.45 1.09 3.59 1.11 3.66

B173 − 17
TABLE 1 Continued
B
Completed Conductor Uncoated Copper Tinned Copper
Area of Cross
Diameter Nominal DC
Nominal Nominal Maximum DC Nominal DC Maximum DC
Number
Section
of Resistance
Size Diameter Mass Resistance @20C Resistance @20C Resistance @20C
Number of
Wires @20C
AWG
of Wires
lb/
Wires in Each
ohm/ ohm/ ohm/ ohm/
cmil mm in. mm in. mm 1000 kg/km ohm/km ohm/km ohm/km ohm/km
Member
1000 ft 1000 ft 1000 ft 1000 ft
ft
6530 3.31 12 49 0.0115 0.29 7 0.104 2.6 20.2 30.1 1.64 5.37 1.67 5.48 1.74 5.70 1.77 5.81
4110 2.08 14 49 0.0092 0.23 7 0.083 2.1 12.9 19.2 2.60 8.53 2.65 8.70 2.79 9.15 2.85 9.33
A
The constructions shown in this table are typical of those used in the industry. It is not intended that this table preclude other constructions that may be desirable for specific applications. The constructions shown provide
for a finished, non-covered, stranded conductor approximately of the area indicated. When specified by the purchaser, the number or size of wires may be increased to provide additional area to compensate for draw-down
during subsequent processing.
B
Values for the nominal diameter and mass of the completed conductor are approximate. The mass values are based upon the standard stranding increments listed in Explanatory Note 6.

B173 − 17
A
TABLE 2 Constructional and DC Resistance Requirements of Rope-Lay Stranded Copper Conductors Having Concentric-Stranded Members—Class H
B
Completed Conductor Uncoated Copper Tinned Copper
Number
Area of Diameter of
Nominal DC Maximum DC
of Nominal Maximum
...