ASTM B258-18

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Designation: B258 − 14 B258 − 18
Standard Specification for
Standard Nominal Diameters and Cross-Sectional Areas of
AWG Sizes of Solid Round Wires Used as Electrical
Conductors
This standard is issued under the fixed designation B258; 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 prescribes standard nominal diameters and cross-sectional areas of American Wire Gage (AWG) sizes of
solid round wires, used as electrical conductors, and gives equations and rules for the calculation of standard nominal mass and
lengths, resistances, and breaking strengths of such wires (Explanatory Note 1).
1.2 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 of the two systems may result in nonconformance with the specification. For
conductor sizes designated by AWG or kcmil sizes, the requirements in SI units have been numerically converted from the
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.
1.2.1 For density, resistivity and temperature, the values stated in SI units are to be regarded as standard.
1.3 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 ASTM Standards:
A111 Specification for Zinc-Coated (Galvanized) “Iron” Telephone and Telegraph Line Wire
A326 Specification for Zinc-Coated (Galvanized) High Tensile Steel Telephone and Telegraph Line Wire (Withdrawn 1990)
B1 Specification for Hard-Drawn Copper Wire
B2 Specification for Medium-Hard-Drawn Copper Wire
B3 Specification for Soft or Annealed Copper Wire
B9 Specification for Bronze Trolley Wire
B33 Specification for Tin-Coated Soft or Annealed Copper Wire for Electrical Purposes
B47 Specification for Copper Trolley Wire
B105 Specification for Hard-Drawn Copper Alloy Wires for Electric 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
B227 Specification for Hard-Drawn Copper-Clad Steel Wire
B230/B230M Specification for Aluminum 1350–H19 Wire for Electrical Purposes
B314 Specification for Aluminum 1350 Wire for Communication Cable (Withdrawn 1994)
B396 Specification for Aluminum-Alloy 5005-H19 Wire for Electrical Purposes (Withdrawn 2003)
B398/B398M Specification for Aluminum-Alloy 6201-T81 and 6201-T83 Wire for Electrical Purposes
B415 Specification for Hard-Drawn Aluminum-Clad Steel Wire
This specification is under the jurisdiction of ASTM Committee B01 on Electrical Conductors and is the direct responsibility of Subcommittee B01.02 on Methods of
Test and Sampling Procedure.
Current edition approved April 1, 2014Oct. 1, 2018. Published April 2014October 2018. Originally approved in 1951. Last previous edition approved in 20082014 as
B258 – 02 (2008).B258 – 14. DOI: 10.1520/B0258-14.10.1520/B0258-18.
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’sstandard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
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B258 − 18
B498/B498M Specification for Zinc-Coated (Galvanized) Steel Core Wire for Use in Overhead Electrical Conductors
B502 Specification for Aluminum-Clad Steel Core Wire for Use in Overhead Electrical Aluminum Conductors
B606 Specification for High-Strength Zinc-Coated (Galvanized) Steel Core Wire for Aluminum and Aluminum-Alloy
Conductors, Steel Reinforced
B609/B609M Specification for Aluminum 1350 Round Wire, Annealed and Intermediate Tempers, for Electrical Purposes
B800 Specification for 8000 Series Aluminum Alloy Wire for Electrical Purposes—Annealed and Intermediate Tempers
B802 Specification for Zinc-5% Aluminum-Mischmetal Alloy-Coated Steel Core Wire for Aluminum Conductors, Steel
Reinforced (ACSR)[Metric](Discontinued 1998-Replaced by B 802/B802M) B0802_B0802M
B803 Specification for High-Strength Zinc–5 % Aluminum-Mischmetal Alloy-Coated Steel Core Wire for Use in Overhead
Electrical Conductors
B957 Specification for Extra-High-Strength and Ultra-High-Strength Zinc-Coated (Galvanized) Steel Core Wire for Overhead
Electrical Conductors
B958 Specification for Extra-High-Strength and Ultra-High-Strength Class A Zinc–5% Aluminum-Mischmetal Alloy-Coated
Steel Core Wire for Use in Overhead Electrical Conductors
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
F205 Test Method for Measuring Diameter of Fine Wire by Weighing
3. Standard Reference Temperature
3.1 For the purpose of this specification, all wire dimensions and properties shall be considered as occurring at the
internationally standardized reference temperature of 20°C (68°F).
4. Standard Rules for Rounding
4.1 All calculations for the standard nominal dimensions and properties of solid round wires shall be rounded in the final value
only, in accordance with rounding method of Practice E29.
5. Standard Nominal Diameters
5.1 Standard nominal diameters of AWG sizes of solid round wires shall be calculated in accordance with the conventional
mathematical law of the American Wire Gage (see Explanatory Note 1) and in accordance with Section 4.
5.2 For wire sizes 4/0 to 44 AWG, inclusive, 10 AWG, inclusive, expressed in mil units, and for wire sizes 4/0 to 18 AWG,
inclusive, expressed in millimetre units, nominal diameters shall be expressed in no more than four significant figures but in no
case closer than the nearest 0.1 mil (0.0001 in.).figures.
5.3 For wire sizes 45 to 56 AWG, inclusive, 11 AWG and smaller, expressed in mil units, and for wire sizes in 19 AWG and
smaller expressed in millimetre units, nominal diameters shall be expressed to the nearest 0.01 mil (0.00001 in.).in no more than
three significant figures.
5.4 The standard nominal diameters expressed in mils and mm have been calculated in accordance with these rules and are given
in Table 1 for convenient reference (Explanatory Note 2). The standard nominal diameters expressed in mm have been calculated
based on the indicated mil diameter value × 0.0254.
6. Standard Nominal Cross-Sectional Areas
6.1 Standard nominal cross-sectional areas in circular mils and square millimetres shall be calculated in accordance with the
following equations and shall be rounded in accordance with Section 4 to the same number of significant figures as used in
expressing the standard diameters, but in no case to less than three significant figures:diameters:
Area, cmil 5 d
2 2 24
Area, mm 5 d 35.067 310
where:
d = diameter of the wire in mils as given in Table 1.
Standard nominal cross-sectional areas in circular mils and square millimetres have been calculated in accordance with the
foregoing rules and are given in Table 1 for convenient reference.
6.2 Standard nominal cross-sectional areas in circular mils and square millimetres have been calculated in accordance with the
foregoing rules and are given in Table 1 for convenient reference.
7. Rules for Calculations Involving Mass and Length
7.1 Standard nominal mass and lengths shall be calculated from the standard wire diameters specified in Table 1, in accordance
with the following equations. They shall be rounded in the final value only, in accordance with Section 4, to the same number of
significant figures as used in expressing the standard diameters, but in no case to less than three significant figures:
B258 − 18
TABLE 1 Standard Nominal Diameters and Cross-Sectional Areas of AWG Sizes of Solid Round Wires at 20°C
Size Diameter Cross-Sectional Area Size Diameter Cross-Sectional Area
2 2
AWG mils mm cmils mm AWG mils mm cmils mm
4/0 460.0 11.684 211 600 107.2 29 11.3 0.287 128 0.0647
4/0 460.0 11.68 211 600 107.2 29 11.3 0.287 128 0.0647
3/0 409.6 10.404 167 800 85.0 30 10.0 0.254 100 0.0507
3/0 409.6 10.40 167 800 85.01 30 10.0 0.254 100 0.0507
2/0 364.8 9.26 133 100 67.4 31 8.9 0.226 79.2 0.0401
2/0 364.8 9.266 133 100 67.43 31 8.90 0.226 79.2 0.0401
1/0 324.9 8.25 105 600 53.5 32 8.0 0.203 64.0 0.0324
1/0 324.9 8.252 105 600 53.49 32 8.00 0.203 64.0 0.0324
1 289.3 7.35 83 690 42.4 33 7.1 0.180 50.4 0.0255
1 289.3 7.348 83 690 42.41 33 7.10 0.180 50.4 0.0255
2 257.6 6.54 66 360 33.6 34 6.3 0.160 39.7 0.0201
2 257.6 6.543 66 360 33.62 34 6.30 0.160 39.7 0.0201
3 229.4 5.82 52 620 26.7 35 5.6 0.142 31.4 0.0159
3 229.4 5.827 52 620 26.66 35 5.60 0.142 31.4 0.0159
4 204.3 5.19 41 740 21.1 36 5.0 0.127 25.0 0.0127
4 204.3 5.189 41 740 21.15 36 5.00 0.127 25.0 0.0127
5 181.9 4.62 33 090 16.8 37 4.5 0.114 20.2 0.0103
5 181.9 4.620 33 090 16.77 37 4.50 0.114 20.2 0.0103
6 162.0 4.11 26 240 13.3 38 4.0 0.102 16.0 0.00811
6 162.0 4.115 26 240 13.30 38 4.00 0.102 16.0 0.00811
7 144.3 3.67 20 820 10.6 39 3.5 0.0890 12.2 0.00621
7 144.3 3.665 20 820 10.55 39 3.50 0.0889 12.2 0.00621
8 128.5 3.26 16 510 8.37 40 3.1 0.0787 9.61 0.00487
8 128.5 3.264 16 510 8.367 40 3.10 0.0787 9.61 0.00487
9 114.4 2.91 13 090 6.63 41 2.8 0.0711 7.84 0.00397
9 114.4 2.906 13 090 6.631 41 2.80 0.0711 7.84 0.00397
10 101.9 2.59 10 380 5.26 42 2.5 0.0635 6.25 0.00317
10 101.9 2.588 10 380 5.261 42 2.50 0.0635 6.25 0.00317
11 90.7 2.30 8 230 4.17 43 2.2 0.0559 4.84 0.00245
11 90.7 2.304 8 230 4.168 43 2.20 0.0559 4.84 0.00245
12 80.8 2.05 6 530 3.31 44 2.0 0.0508 4.00 0.00203
12 80.8 2.052 6 530 3.308 44 2.00 0.0508 4.00 0.00203
13 72.0 1.83 5 180 2.63 45 1.76 0.0447 3.10 0.00157
13 72.0 1.829 5 180 2.627 45 1.76 0.0447 3.10 0.00157
14 64.1 1.63 4 110 2.08 46 1.57 0.0399 2.46 0.00125
14 64.1 1.628 4 110 2.082 46 1.57 0.0399 2.46 0.00125
15 57.1 1.45 3 260 1.65 47 1.40 0.0356 1.96 0.000993
15 57.1 1.450 3 260 1.652 47 1.40 0.0356 1.96 0.000993
16 50.8 1.29 2 580 1.31 48 1.24 0.0315 1.54 0.000779
16 50.8 1.290 2 580 1.308 48 1.24 0.0315 1.54 0.000779
17 45.3 1.15 2 050 1.04 49 1.11 0.0282 1.23 0.000624
17 45.3 1.151 2 050 1.040 49 1.11 0.0282 1.23 0.000624
18 40.3 1.02 1 620 0.823 50 0.99 0.0252 0.980 0.000497
18 40.3 1.024 1 620 0.823 50 0.99 0.0252 0.980 0.000497
19 35.9 0.904 1 290 0.653 51 0.88 0.0224 0.774 0.000392
19 35.9 0.912 1 290 0.653 51 0.88 0.0224 0.774 0.000392
20 32.0 0.813 1 020 0.519 52 0.78 0.0198 0.608 0.000308
21 28.5 0.724 812 0.412 53 0.70 0.0178 0.490 0.000248
22 25.3 0.643 640 0.324 54 0.62 0.0158 0.384 0.000195
22 25.3 0.643 640 0.324 54 0.62 0.0157 0.384 0.000195
23 22.6 0.574 511 0.259 55 0.55 0.0140 0.302 0.000153
24 20.1 0.511 404 0.205 56 0.49 0.0125 0.240 0.000122
24 20.1 0.511 404 0.205 56 0.49 0.0124 0.240 0.000122
25 17.9 0.455 320 0.162
26 15.9 0.404 253 0.128
27 14.2 0.361 202 0.102
28 12.6 0.320 159 0.0804
2 23
W 5 d 3δ30.34049 310
2 6
L 5 ~1/d !3~1/δ!32.9369 310
where:
W = mass, lb/1000 ft,
d = diameter of the wire in mils as given in Table 1,
δ = density of the wire material at 20°C in g/cm as given in Table 2, and
L = length, ft/lb.
8. Rules for Calculations Involving Resistivity
8.1 Standard nominal resistances and other values derived from the resistivity units shall be calculated from the standard wire
diameters specified in Table 1 in accordance with the following equations. All values so derived shall be rounded in the final value
B258 − 18
TABLE 2 Density and Resistivity of Electrical Conductor Materials
A
Density, δ, at Density,δ, at Resistivity, ρ, at
Resistivity , ρ, at
Material Material
3 3 2
20°C, g/cm 20°C, Ω· lb/mile 20°C, g/cm 20°C Ω· lb/mile
A
Density, δ, at Resistivity , ρ, at Density,δ, at Resistivity, ρ, at
Material Material
3 2 3 2
20°C, Ω· lb/mile
20°C, g/cm 20°C, g/cm 20°C Ω· lb/mile
Copper (Specifications B1, B2, Aluminum-Clad Steel (Specification 6.59 3191
Copper (Specifications Aluminum-Clad Steel (Specifications 6.59 3191
B3, B33, B47 and B189), B415 and B502)
Volume Conductivity, % Copper-Clad Steel (Specification
IACS: B227):
100 8.89 875.20 Grade 30 HS 8.15 2728
97.66 8.89 896.15 Grade 30 HS 8.15 2728
97.66 8.89 896.15 Grade 30 EHS 8.15 2728
97.16 8.89 900.77 Grade 30 EHS 8.15 2728
97.16 8.89 900.77 Grade 40 8.15 2045
96.66 8.89 905.44 Grade 40 EHS 8.15 2045
96.16 8.89 910.15 Grade 40 EHS 8.15 2045
94.16 8.89 929.52 Galvanized Steel (Telephone and
96.16 8.89 910.15 Galvanized Steel (Telephone and
94.16 8.89 929.52 Telegraph) (Specification A111):
93.15 8.89 939.51 Telegraph) (Specification
93.15 8.89 939.51 Class A Coating:
Bronze (Specification B9): A111):
Bronze (Specification B9): Grade EBB (Non-Copper 7.78 5000
Class A 8.89 2188 Class A Coating:
Class B 8.89 1346 Grade EBB (Non-Copper 7.78 5000
Class C 8.89 1094 Bearing)
Class A 8.89 2188 Bearing)
Copper Alloys (Specification Grade BB (Copper Bearing) 7.78 5800
Class B 8.89 1346 Grade BB (Copper Bearing) 7.78 5800
B
B105 ): Grade BB (Non-Copper 7.78 5600
Class C 8.89 1094 Grade BB (Non-Copper 7.78 5600
B
Copper Alloys (Specification B105 ): Bearing)
Grade 8.5 8.78 10 169 Bearing)
Grade 8.5 8.78 10 169 Class B Coating:
Grade 13 8.78 6649 Class B Coating:
Grade 15 8.54 5605 Grade EBB (Non-Copper 7.78 4900
Grade 13 8.78 6649 Grade EBB (Non-Copper 7.78 4900
Grade 20 8.89 4376 Bearing)
Grade 15 8.54 5605 Bearing)
Grade 30 8.89 2917 Grade BB (Copper Bearing) 7.78 5600
Grade 20 8.89 4376 Grade BB (Copper Bearing) 7.78 5600
Grade 40 8.89 2188 Grade BB (Non-Copper 7.78 5450
Grade 30 8.89 2917 Grade BB (Non-Copper 7.78 5450
Grade 55 8.89 1591 Bearing)
Grade 40 8.89 2188 Bearing)
Grade 65 8.89 1346 Class C Coating:
Grade 55 8.89 1591 Class C Coating:
Grade 74 8.89 1183 Grade EBB (Non-Copper 7.78 4800
Grade 65 8.89 1346 Grade EBB (Non-Copper 7.78 4800
Grade 80 8.89 10
...