ASTM B33-10(2014)
(Specification)Standard Specification for Tin-Coated Soft or Annealed Copper Wire for Electrical Purposes
Standard Specification for Tin-Coated Soft or Annealed Copper Wire for Electrical Purposes
ABSTRACT
This specification covers tinned, round, soft, or annealed copper wire for electrical purposes. The tinned wire shall conformto the required tensile strength and elongation. Electrical resistivity shall be measured. The wire sizes shall be expressed as the diameter of the wire and shall be measured using micrometre caliper equipped with a vernier. The tin coating shall be continuous. The continuity of the wire shall be determined on representative samples taken before stranding or insulating. The continuity of tinning shall be determined by the hydrochlroic acid-sodium polysulfide test. The tin coating shall be firmly adherent to the surface of the copper. The adherence of coating on the wire shall be determined on representative samples taken before stranding or insulating. The adherence of coating shall be determined by the wrapping and immersion test.
SCOPE
1.1 This specification covers tin-coated, round, soft, or annealed copper wire for electrical purposes.
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.2.1 Exceptions—The SI values for density, resistivity, and volume are to be regarded as standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:B33 −10 (Reapproved 2014)
Standard Specification for
Tin-Coated Soft or Annealed Copper Wire for Electrical
Purposes
This standard is issued under the fixed designation B33; the number immediately following the designation indicates the year of original
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
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 3.1.1 Quantity of each size,
3.1.2 Wire size-diameter in inches (see 5.3 and Table 1),
1.1 This specification covers tin-coated, round, soft, or
3.1.3 Type of copper, if special (see 4.2),
annealed copper wire for electrical purposes.
3.1.4 Package size (see 10.1),
1.2 The values stated in inch-pound units are to be regarded
3.1.5 Special packaging marking, if required, and
as standard. The values given in parentheses are mathematical
3.1.6 Place of inspection (see 7.1).
conversions to SI units that are provided for information only
4. Material
and are not considered standard.
1.2.1 Exceptions—The SI values for density, resistivity, and
4.1 Tin for Coating—The tin used for coating shall be
volume are to be regarded as standard.
commercially pure (Explanatory Note 1). For purposes of this
specification, the tin shall be considered commercially pure if
1.3 This standard does not purport to address all of the
the total of other elements, exclusive of copper, does not
safety concerns, if any, associated with its use. It is the
exceed 1 %. Notwithstanding the previous sentence, chemical
responsibility of the user of this standard to establish appro-
analysisofthetincoatingorofthetinusedforcoatingshallnot
priate safety and health practices and determine the applica-
be required under this specification. Adequacy of the tin
bility of regulatory limitations prior to use.
coatingisassuredbythecontinuityofcoatingandadherenceof
2. Referenced Documents
coating requirements (see 5.4 and 5.5, respectively).
2.1 ASTM Standards:
4.2 Copper-Base Metal—The base metal shall be copper of
B49 Specification for Copper Rod Drawing Stock for Elec-
such quality and purity that the finished product shall have
trical Purposes
properties and characteristics prescribed in this specification.
B193 Test Method for Resistivity of Electrical Conductor
NOTE 1—Specification B49 defines copper suitable for use.
Materials
B258 Specification for Nominal Diameters and Cross- 4.3 Copper bars of special qualities, forms, or types, as may
SectionalAreasofAWGSizesofSolidRoundWiresUsed be agreed upon between the manufacturer and the purchaser,
as Electrical Conductors and which will conform to the requirements prescribed in this
2.2 Other Document: specification, may also be used.
NBS Handbook 100 Copper Wire Tables
5. General Requirements (See Section 8)
3. Ordering Information
5.1 Tensile Strength and Elongation (Explanatory Note 2
3.1 Orders for material under this specification shall include and Note 3)—The tinned wire shall conform to the require-
the following information:
ments for elongation prescribed in Table 1. No requirements
for tensile strength are specified. For wire whose nominal
diameter is more than 0.001 in. (0.025 mm) greater than a size
This specification is under the jurisdiction of ASTM Committee B01 on
Electrical Conductors and is the direct responsibility of Subcommittee B01.04 on
listed in Table 1, but less than that of the next larger size, the
Conductors of Copper and Copper Alloys.
requirements of the next larger size shall apply.
Current edition approved Sept. 1, 2014. Published September 2014. Originally
approved in 1919. Last previous edition approved in 2010 as B33 – 10. DOI:
5.2 Resistivity (Explanatory Note 1 and Note 4)—The elec-
10.1520/B0033-10R14.
trical resistivity of tinned wire at a temperature of 20°C shall
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
not exceed the values prescribed in Table 2.
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
5.3 Dimensions and Permissible Variations (Explanatory
the ASTM website.
3 Note 2)—The wire sizes shall be expressed as the diameter of
Available from National Technical Information Service (NTIS), 5301 Shawnee
Rd., Alexandria, VA 22312, http://www.ntis.gov. thewireindecimalfractionsofaninchtothenearest0.0001in.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B33−10 (2014)
TABLE 1 Tensile Requirements
(0.0025 mm). The tin-coated wire shall not vary from the
Diameter Area at 20°C specified diameter by more than the amounts prescribed in
Elongation
Table 3.
in 10 in.
(250 mm),
5.4 Continuity of Coating—The tin coating shall be continu-
2 2
in. mm cmil in. mm %min
ous. The continuity of coating on the wire shall be determined
0.4600 11.684 211600 0.1662 107.0 30
on representative samples taken before stranding or insulating.
0.4096 10.404 167800 0.1318 85.0 30
The continuity of tinning shall be determined by the hydro-
0.3648 9.266 133100 0.1045 67.4 30
0.3249 8.252 105600 0.08291 53.5 30
chloric acid-sodium polysulfide test in accordance with 6.3.
0.2893 7.348 83690 0.06573 42.4 25 5.5 Adherence of Coating—The tin coating shall be firmly
0.2576 6.543 66360 0.05212 33.6 25
adherent to the surface of the copper.The adherence of coating
0.2294 5.827 52620 0.04133 26.7 25
on the wire shall be determined on representative samples
0.2043 5.189 41740 0.03278 21.2 25
taken before stranding or insulating. The adherence of coating
0.1819 4.620 33090 0.02599 16.8 25
shall be determined by the wrapping and immersion test in
0.1620 4.115 26240 0.02061 13.3 25
accordancewith6.4for0.0320in.(0.813mm)andlargersizes.
0.1443 3.665 20820 0.01635 10.6 25
0.1285 3.264 16510 0.01297 8.37 25
5.6 Joints—Necessary joints in the completed wire and in
the wire and rods prior to final drawing shall be made in
0.1144 2.906 13090 0.01028 6.63 25
0.1019 2.588 10380 0.008155 5.26 20
accordance with the best commercial practice.
0.0907 2.304 8230 0.00646 4.17 20
0.0808 2.052 6530 0.00513 3.31 20 5.7 Finish—The coating shall consist of a smooth continu-
ouslayer,firmlyadherenttothesurfaceofthecopper.Thewire
0.0720 1.829 5180 0.00407 2.63 20
shall be free of all imperfections not consistent with the best
0.0641 1.628 4110 0.00323 2.08 20
0.0571 1.450 3260 0.00256 1.65 20 commercial practice.
0.0508 1.290 2580 0.00203 1.31 20
6. Test Methods
0.0453 1.151 2050 0.00161 1.04 20
0.0403 1.024 1620 0.00128 0.823 20
6.1 Tensile Strength and Elongation (Explanatory Note 5):
0.0359 0.912 1290 0.00101 0.653 20
6.1.1 No test for tensile strength shall be required.
0.0320 0.813 1020 0.000804 0.519 20
6.1.2 The elongation of wire with a nominal diameter
0.0285 0.724 812 0.000638 0.412 20
greater than 0.0808 in. (2.052 mm) shall be determined as the
0.0253 0.643 640 0.000503 0.324 20
permanent increase in length due to the breaking of the wire in
0.0226 0.574 511 0.000401 0.259 20
tension.The elongation shall be measured between gage marks
0.0201 0.511 404 0.000317 0.205 15
placed originally 10 in. (254 mm) apart upon the test specimen
0.0179 0.455 320 0.000252 0.162 15
and expressed in percent of the original length.
0.0159 0.404 253 0.000199 0.128 15
6.1.3 The elongation of wire with a nominal diameter equal
0.0142 0.361 202 0.000158 0.102 15
0.0126 0.320 159 0.000125 0.080 15
to or less than 0.0808 in. (2.053 mm) may be determined as
describedaboveorbymeasurementsmadebetweenthejawsof
0.0113 0.287 128 0.000100 0.065 15
the testing machine. When measurements are made between
0.0100 0.254 100 0.0000785 0.051 10
0.0089 0.226 79.2 0.0000622 0.040 10
the jaws, the zero length shall be the distance between the jaws
0.0080 0.203 64.0 0.0000503 0.032 10
at the start of the tension test and be as near 10 in. (254 mm)
as practicable. The final length shall be the distance between
0.0071 0.180 50.4 0.0000396 0.026 10
0.0063 0.160 39.7 0.0000312 0.020 10
the jaws at the time of rupture. The fracture shall be between
0.0056 0.142 31.4 0.0000246 0.016 10
gage marks or jaws of the testing machine, depending on
0.0050 0.127 25.0 0.0000196 0.013 10
method used, and not closer than 1 in. (25.4 mm) to either gage
0.0045 0.114 20.3 0.0000159 0.010 10
mark or jaw.
0.0040 0.102 16.0 0.0000126 0.0081 10
0.0035 0.089 12.3 0.00000962 0.0062 10 6.2 Dimensional Measurements—Dimensional measure-
0.0031 0.079 9.61 0.00000755 0.0049 10
ments shall be made with a micrometer caliper equipped with
a vernier graduated in 0.0001 in. (0.0025 mm). Measurements
shall be made on at least three places on each unit selected for
TABLE 2 Electrical Resistivity Requirements
this test. If accessible, one measurement shall be taken on each
Nominal Diameter Resistivity at 20°C
end and one near the middle. The average of the three
2 2
measurements shall determine compliance with the require-
in. mm Ω·lb/mile Ω·g/m
ments.
0.460 to 0.290, incl 11.7 to 7.4, incl 896.15 0.15695
Under 0.290 to 0.103, incl Under 7.4 to 2.6, incl 900.77 0.15776
Under 0.103 to 0.0201, incl Under 2.6 to 0.51, incl 910.15 0.15940
TABLE 3 Permissible Variations in Diamter
Under 0.0201 to 0.0111 incl Under 0.51 to 0.28, incl 929.52 0.16279
Under 0.0111 to 0.0030, incl Under 0.28 to 0.076, incl 939.51 0.16454 Permissible Variations in Diameter
Nominal Diameter of Wire
in. mm
in. mm plus minus plus minus
Under 0.0100 Under 0.25 0.0003 0.00010 0.0076 0.0025
0.0100 and over 0.25 and over 3 % 1 % 3 % 1 %
B33−10 (2014)
6.3 Continuity of Coating: min in the HCl solution, wash, and dry; (4) immerse the
6.3.1 Specimens: specimenfor30sinthesodiumpolysulfidesolution,wash,and
6.3.1.1 Length of Specimens—Test specimens shall have a wipe dry.
lengthofabout6in.(152mm).Theyshallbetaggedormarked
6.3.3.2 Washing Specimens—After each immersion, imme-
tocorrespondwiththecoil,spool,orreelfromwhichtheywere
diately wash the specimens thoroughly in clean water and wipe
cut.
dry with a clean, soft cloth.
6.3.1.2 Treatment of Specimens—The specimens shall be
6.3.3.3 Examination of Specimens—After immersion and
thoroughly cleaned by immersion in a suitable organic solvent
washing, examine the specimens to ascertain if copper exposed
for at least 3 min; then removed and wiped dry with a clean,
through openings in the tin coating has been blackened by
soft cloth (Caution—see Explanatory Note 6). The specimens
action of the sodium polysulfide. The specimens shall be
thus cleaned shall be kept wrapped in a clean, dry cloth until
considered to have failed if, by such blackening, exposed
tested. That part of the specimen to be immersed in the test
copper is revealed. No attention shall be paid to blackening
solution shall not be handled. Care shall be taken to avoid
within 0.5 in. (12.7 mm) of the cut end. A grayish brown
abrasion by the cut ends.
appearance of the coating shall not constitute failure.
6.3.2 Special Solutions Required:
6.4 Adherence of Coating:
6.3.2.1 Hydrochloric Acid Solution (HCl) (sp gr 1.088)—
6.4.1 Specimens:
Commercial HCl (sp gr 1.12) shall be diluted with distilled
6.4.1.1 Length of Specimens—Test specimens shall be ap-
water to a specific gravity of 1.088 measured at 15.6°C (60°F).
proximately 12 in. (305 mm) in length and shall be tagged or
Aportion of HCl solution having a volume of 180 mLshall be
marked to correspond with the coil, spool, or reel from which
considered to be exhausted when the number of test specimens
they are cut.
prescribed in Table 4 of a size as indicated in 6.3.3 have been
immersed in it for two cycles. 6.4.1.2 Treatment of Specimens—The specimens shall be
thoroughly cleaned, if required, by immersion in a suitable
6.3.2.2 Sodium Polysulfide Solution (sp gr 1.142) (Ex-
planatory Note 7)—A concentrated solution shall be made by organic solvent for at least 3 min, then removed and dried
(Caution—see Explanatory Note 6). The specimens thus
dissolving sodium sulfide cp crystals in distilled water until the
solutionissaturatedatabout21°C(70°F),andaddingsufficient cleaned shall be kept wrapped in a clean dry cloth until tested.
That part of the specimens to be immersed in the test solution
flowers of sulfur (in excess of 250 g/L of solution) to provide
complete saturation, as shown by the presence in the solution shall not be handled. Care shall be taken to avoid abrasion of
the surface to be subjected to test. Wire of sizes 0.005 in. (0.13
of an excess of sulfur after the solution has been allowed to
stand for at least 24 h. The test solution shall be made by mm) and smaller may be cleaned after wrapping around the
mandrel.
diluting a portion of the concentrated solution with distilled
water to a specific gravity of 1.135 to 1.145 at 15.6°C (60°F).
6.4.2 Procedure:
The sodium polysulfide test solution should have sufficient
6.4.2.1 Wrapping—Slowly wrap the test specimen in a
strengthtoblackenthoroughlyapieceofcleanuntinnedcopper
suitable manner in an open helix around a polished mandrel
wire in 5 s. The test solution used for testing samples shall be
having rounded ends and a diameter not to exceed four times
considered exhausted if it fails to blacken a piece of clean
the nominal diameter of the specimen. Take care not to stretch
copper as described above.
the specimen during the wrapping operation. The spacing of
6.3.3 Procedure:
the consecutive turns shall be approximately equal to the
6.3.3.1 Immersion of Specimens—Immerse a length of at
diameterofthewire.Forsizes0.021in.(0.53mm)andsmaller,
least 4- ⁄2 in. (114 mm) from each of the clean specimens, in
notmorethansixhelicalturnsshallbeusedforthetest,andfor
accordance with the following cycles, in test solutions main-
wire larger than 0.021 in., not more than three turns shall be
tained at a temperature between 15.6 and 21°C (60 and 70°F):
used.
(1) Immerse the specimen for 1 min in the HCl solution
6.4.2.2 Immersion Test—Removethehelicallywrappedpor-
described in 6.3.2, wash, and wipe dry; (2) immerse the
tion of the test specimen from the mandrel and immerse
specimen for 30 s in the sodium polysulfide solution described
completelyinthesodiumpolysulfidesolution(see6.3.2)for30
in 6.3.2, wash, and wipe dry; (3) immerse the specimen for 1
s at the temperature prescribed in 6.3.3. On removal from the
sodiumpolysulfidesolution,immediatelyrinsethespecimenin
clean water and remove the excess by shaking.
6.4.2.3 Examination of Specimens—Examine visually the
TABLE 4 Limiting Number of Test Specimens for Coating Tests
outer peripheral surface of the helically wrapped portion of the
Maximum Number of
specimen. For wire
...
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: B33 − 10 B33 − 10 (Reapproved 2014)
Standard Specification for
Tin-Coated Soft or Annealed Copper Wire for Electrical
Purposes
This standard is issued under the fixed designation B33; 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 tin-coated, round, soft, or annealed copper wire for electrical purposes.
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
1.2.1 Exceptions—The SI values for density, resistivity, and volume are to be regarded as standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
B49 Specification for Copper Rod Drawing Stock for Electrical Purposes
B193 Test Method for Resistivity of Electrical Conductor Materials
B258 Specification for Nominal Diameters and Cross-Sectional Areas of AWG Sizes of Solid Round Wires Used as Electrical
Conductors
2.2 Other Document:
NBS Handbook 100 Copper Wire Tables
3. Ordering Information
3.1 Orders for material under this specification shall include the following information:
3.1.1 Quantity of each size,
3.1.2 Wire size-diameter in inches (see 5.3 and Table 1),
3.1.3 Type of copper, if special (see 4.2),
3.1.4 Package size (see 10.1),
3.1.5 Special packaging marking, if required, and
3.1.6 Place of inspection (see 7.1).
4. Material
4.1 Tin for Coating—The tin used for coating shall be commercially pure (Explanatory Note 1). For purposes of this
specification, the tin shall be considered commercially pure if the total of other elements, exclusive of copper, does not exceed 1%.
1 %. Notwithstanding the previous sentence, chemical analysis of the tin coating or of the tin used for coating shall not be required
under this specification. Adequacy of the tin coating is assured by the continuity of coating and adherence of coating requirements
(see 5.4 and 5.5, respectively).
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, 2010Sept. 1, 2014. Published May 2010September 2014. Originally approved in 1919. Last previous edition approved in 20042010 as
B33 – 04.B33 – 10. DOI: 10.1520/B0033-10.10.1520/B0033-10R14.
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.
Available from National Technical Information Service (NTIS), U.S. Department of Commerce, 5285 Port Royal Rd., Springfield, VA 22161.5301 Shawnee Rd.,
Alexandria, VA 22312, http://www.ntis.gov.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B33 − 10 (2014)
TABLE 1 Tensile Requirements
Diameter Area at 20°C
Elongation
in 10 in.
(250 mm),
2 2
in. mm cmil in. mm % min
0.4600 11.684 211600 0.1662 107.0 30
0.4096 10.404 167800 0.1318 85.0 30
0.3648 9.266 133100 0.1045 67.4 30
0.3249 8.252 105600 0.08291 53.5 30
0.2893 7.348 83690 0.06573 42.4 25
0.2576 6.543 66360 0.05212 33.6 25
0.2294 5.827 52620 0.04133 26.7 25
0.2043 5.189 41740 0.03278 21.2 25
0.1819 4.620 33090 0.02599 16.8 25
0.1620 4.115 26240 0.02061 13.3 25
0.1443 3.665 20820 0.01635 10.6 25
0.1285 3.264 16510 0.01297 8.37 25
0.1144 2.906 13090 0.01028 6.63 25
0.1019 2.588 10380 0.008155 5.26 20
0.0907 2.304 8230 0.00646 4.17 20
0.0808 2.052 6530 0.00513 3.31 20
0.0720 1.829 5180 0.00407 2.63 20
0.0641 1.628 4110 0.00323 2.08 20
0.0571 1.450 3260 0.00256 1.65 20
0.0508 1.290 2580 0.00203 1.31 20
0.0453 1.151 2050 0.00161 1.04 20
0.0403 1.024 1620 0.00128 0.823 20
0.0359 0.912 1290 0.00101 0.653 20
0.0320 0.813 1020 0.000804 0.519 20
0.0285 0.724 812 0.000638 0.412 20
0.0253 0.643 640 0.000503 0.324 20
0.0226 0.574 511 0.000401 0.259 20
0.0201 0.511 404 0.000317 0.205 15
0.0179 0.455 320 0.000252 0.162 15
0.0159 0.404 253 0.000199 0.128 15
0.0142 0.361 202 0.000158 0.102 15
0.0126 0.320 159 0.000125 0.080 15
0.0113 0.287 128 0.000100 0.065 15
0.0100 0.254 100 0.0000785 0.051 10
0.0089 0.226 79.2 0.0000622 0.040 10
0.0080 0.203 64.0 0.0000503 0.032 10
0.0071 0.180 50.4 0.0000396 0.026 10
0.0063 0.160 39.7 0.0000312 0.020 10
0.0056 0.142 31.4 0.0000246 0.016 10
0.0050 0.127 25.0 0.0000196 0.013 10
0.0045 0.114 20.3 0.0000159 0.010 10
0.0040 0.102 16.0 0.0000126 0.0081 10
0.0035 0.089 12.3 0.00000962 0.0062 10
0.0031 0.079 9.61 0.00000755 0.0049 10
4.2 Copper-Base Metal—The base metal shall be copper of such quality and purity that the finished product shall have
properties and characteristics prescribed in this specification.
NOTE 1—Specification B49 defines copper suitable for use.
4.3 Copper bars of special qualities, forms, or types, as may be agreed upon between the manufacturer and the purchaser, and
which will conform to the requirements prescribed in this specification, may also be used.
5. General Requirements (See Section 8)
5.1 Tensile Strength and Elongation (Explanatory Note 2 and Note 3)—The tinned wire shall conform to the requirements for
elongation prescribed in Table 1. No requirements for tensile strength are specified. For wire whose nominal diameter is more than
0.001 in. (0.025 mm) greater than a size listed in Table 1, but less than that of the next larger size, the requirements of the next
larger size shall apply.
B33 − 10 (2014)
5.2 Resistivity (Explanatory Note 1 and Note 4)—The electrical resistivity of tinned wire at a temperature of 20°C shall not
exceed the values prescribed in Table 2.
5.3 Dimensions and Permissible Variations (Explanatory Note 2)—The wire sizes shall be expressed as the diameter of the wire
in decimal fractions of an inch to the nearest 0.0001 in. (0.0025 mm). The tin-coated wire shall not vary from the specified diameter
by more than the amounts prescribed in Table 3.
5.4 Continuity of Coating—The tin coating shall be continuous. The continuity of coating on the wire shall be determined on
representative samples taken before stranding or insulating. The continuity of tinning shall be determined by the hydrochloric
acid-sodium polysulfide test in accordance with 6.3.
5.5 Adherence of Coating—The tin coating shall be firmly adherent to the surface of the copper. The adherence of coating on
the wire shall be determined on representative samples taken before stranding or insulating. The adherence of coating shall be
determined by the wrapping and immersion test in accordance with 6.4 for 0.0320 in. (0.813 mm) and larger sizes.
5.6 Joints—Necessary joints in the completed wire and in the wire and rods prior to final drawing shall be made in accordance
with the best commercial practice.
5.7 Finish—The coating shall consist of a smooth continuous layer, firmly adherent to the surface of the copper. The wire shall
be free of all imperfections not consistent with the best commercial practice.
6. Test Methods
6.1 Tensile Strength and Elongation (Explanatory Note 5):
6.1.1 No test for tensile strength shall be required.
6.1.2 The elongation of wire with a nominal diameter greater than 0.0808 in. (2.052 mm) shall be determined as the permanent
increase in length due to the breaking of the wire in tension. The elongation shall be measured between gage marks placed
originally 10 in. (254 mm) apart upon the test specimen and expressed in percent of the original length.
6.1.3 The elongation of wire with a nominal diameter equal to or less than 0.0808 in. (2.053 mm) may be determined as
described above or by measurements made between the jaws of the testing machine. When measurements are made between the
jaws, the zero length shall be the distance between the jaws at the start of the tension test and be as near 10 in. (254 mm) as
practicable. The final length shall be the distance between the jaws at the time of rupture. The fracture shall be between gage marks
or jaws of the testing machine, depending on method used, and not closer than 1 in. (25.4 mm) to either gage mark or jaw.
6.2 Dimensional Measurements—Dimensional measurements shall be made with a micrometer caliper equipped with a vernier
graduated in 0.0001 in. (0.0025 mm). Measurements shall be made on at least three places on each unit selected for this test. If
accessible, one measurement shall be taken on each end and one near the middle. The average of the three measurements shall
determine compliance with the requirements.
6.3 Continuity of Coating:
6.3.1 Specimens:
6.3.1.1 Length of Specimens—Test specimens shall have a length of about 6 in. (152 mm). They shall be tagged or marked to
correspond with the coil, spool, or reel from which they were cut.
6.3.1.2 Treatment of Specimens—The specimens shall be thoroughly cleaned by immersion in a suitable organic solvent for at
least 3 min; then removed and wiped dry with a clean, soft cloth (Caution-Caution—see Explanatory Note 6). The specimens thus
cleaned shall be kept wrapped in a clean, dry cloth until tested. That part of the specimen to be immersed in the test solution shall
not be handled. Care shall be taken to avoid abrasion by the cut ends.
6.3.2 Special Solutions Required:
6.3.2.1 Hydrochloric Acid Solution (HCl) (sp gr 1.088)—Commercial HCl (sp gr 1.12) shall be diluted with distilled water to
a specific gravity of 1.088 measured at 15.6°C (60°F). A portion of HCl solution having a volume of 180 mL shall be considered
to be exhausted when the number of test specimens prescribed in Table 4 of a size as indicated in 6.3.3 have been immersed in
it for two cycles.
6.3.2.2 Sodium Polysulfide Solution (sp gr 1.142) (Explanatory Note 7)—A concentrated solution shall be made by
dissolving sodium sulfide cp crystals in distilled water until the solution is saturated at about 21°C (70°F), and adding sufficient
TABLE 2 Electrical Resistivity Requirements
Nominal Diameter Resistivity at 20°C
2 2
in. mm Ω·lb/mile Ω·g/m
0.460 to 0.290, incl 11.7 to 7.4, incl 896.15 0.15695
Under 0.290 to 0.103, incl Under 7.4 to 2.6, incl 900.77 0.15776
Under 0.103 to 0.0201, incl Under 2.6 to 0.51, incl 910.15 0.15940
Under 0.0201 to 0.0111 incl Under 0.51 to 0.28, incl 929.52 0.16279
Under 0.0111 to 0.0030, incl Under 0.28 to 0.076, incl 939.51 0.16454
B33 − 10 (2014)
TABLE 3 Permissible Variations in Diamter
Permissible Variations in Diameter
Nominal Diameter of Wire
in. mm
in. mm plus minus plus minus
Under 0.0100 Under 0.25 0.0003 0.00010 0.0076 0.0025
0.0100 and over 0.25 and over 3 % 1 % 3 % 1 %
TABLE 4 Limiting Number of Test Specimens for Coating Tests
Maximum Number of
Specimens to be Tested
Nominal Diameter, in.
for 2 Cycles in 180 mL of
Acid Solution
0.460 to 0.141, incl 2
Under 0.141 to 0.0851, incl 4
Under 0.0851 to 0.0501, incl 6
Under 0.0501 to 0.0381, incl 10
Under 0.0381 to 0.0301, incl 12
Under 0.0301 to 0.0030, incl 14
flowers of sulfur (in excess of 250 g/L of solution) to provide complete saturation, as shown by the presence in the solution of an
excess of sulfur after the solution has been allowed to stand for at least 24 h. The test solution shall be made by diluting a portion
of the concentrated solution with distilled water to a specific gravity of 1.135 to 1.145 at 15.6°C (60°F). The sodium polysulfide
test solution should have sufficient strength to blacken thoroughly a piece of clean untinned copper wire in 5 s. The test solution
used for testing samples shall be considered exhausted if it fails to blacken a piece of clean copper as described above.
6.3.3 Procedure:
6.3.3.1 Immersion of Specimens—Immerse a length of at least 4- ⁄2 in. (114 mm) from each of the clean specimens, in
accordance with the following cycles, in test solutions maintained at a temperature between 15.6 and 21°C (60 and 70°F): (1)
Immerse the specimen for 1 min in the HCl solution described in 6.3.2, wash, and wipe dry; (2) immerse the specimen for 30 s
in the sodium polysulfide solution described in 6.3.2, wash, and wipe dry; (3) immerse the specimen for 1 min in the HCl solution,
wash, and dry; (4) immerse the specimen for 30 s in the sodium polysulfide solution, wash, and wipe dry.
6.3.3.2 Washing Specimens—After each immersion, immediately wash the specimens thoroughly in clean water and wipe dry
with a clean, soft cloth.
6.3.3.3 Examination of Specimens—After immersion and washing, examine the specimens to ascertain if copper exposed
through openings in the tin coating has been blackened by action of the sodium polysulfide. The specimens shall be considered
to have failed if, by such blackening, exposed copper is revealed. No attention shall be paid to blackening within 0.5 in. (12.7 mm)
of the cut end. A grayish brown appearance of the coating shall not constitute failure.
6.4 Adherence of Coating:
6.4.1 Specimens:
6.4.1.1 Length of Specimens—Test specimens shall be approximately 12 in. (305 mm) in length and shall be tagged or marked
to correspond with the coil, spool, or reel from which they are cut.
6.4.1.2 Treatment of Specimens—The specimens shall be thoroughly cleaned, if required, by immersion in a suitable organic
solvent for at least 3 min, then removed and dried (Caution-Caution—see Explanatory Note 6). The specimens thus cleaned shall
be kept wrapped in a clean dry cloth until tested. That part of the specimens to be immersed in the test solution shall not be handled.
Care shall be taken to avoid abrasion of the surface to be subjected to test. Wire of sizes 0.005 in. (0.13 mm) and smaller may be
cleaned after wrapping around the mandrel.
6.4.2 Procedure:
6.4.2.1 Wrapping—Slowly wrap the test specimen in a suitable manner in an open helix around a polishe
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