ASTM B738-03(2008)

Standard Specification for Fine-Wire Bunch-Stranded and Rope-Lay Bunch-Stranded Copper Conductors for Use as Electrical Conductors

ABSTRACT
This specification deals with bare fine-wire bunch-stranded and rope-lay bunch-stranded copper conductors made from round copper wires finer than No. 40 AWG, either coated or uncoated with tin or silver, for use as electrical conductors. The conductor types covered in this specification are designated Type B for bunch-stranded conductors, and Type R for rope-lay bunch-stranded conductors. On the other hand, the wire classifications are assigned as: Class R, stranded conductors using wire 42 AWG; Class S, stranded conductors using wire 44 AWG; Class T, stranded conductors using wire 46 AWG; Class U, stranded conductors using wire 48 AWG; and Class V, stranded conductors using wire 50 AWG. Wires shall undergo tests that shall evaluated their conformance to physical and electrical properties such as wire cross-sectional area and diameter, coating thickness, tensile strength, elongation, and DC resistance.
SCOPE
1.1 This specification covers bare bunch-stranded and rope-lay bunch-stranded conductors made from round copper wires finer than No. 40 AWG with diameters less than 0.0031 in. (.078 mm), either coated or uncoated with tin or silver, for use as electrical conductors. (Explanatory Note 1).
1.2 The values (SI units) for density and temperature 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.

General Information

• Status: Historical
• Publication Date: 31-Mar-2008
• ICS: 29.050 - Superconductivity and conducting materials
• Technical Committee: B01 - Electrical Conductors
• Drafting Committee: B01.04 - Conductors of Copper and Copper Alloys

Relations

• Replaces: ASTM B738-03 - Standard Specification for Fine-Wire Bunch-Stranded and Rope-Lay Bunch-Stranded Copper Conductors for Use as Electrical Conductors
• Effective Date: 01-Apr-2008
• Replaced By: ASTM B738-13 - Standard Specification for Fine-Wire Bunch-Stranded and Rope-Lay Bunch-Stranded Copper Conductors for Use as Electrical Conductors
• Effective Date: 01-Apr-2013

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:B738 −03(Reapproved 2008)
Standard Specification for
Fine-Wire Bunch-Stranded and Rope-Lay Bunch-Stranded
Copper Conductors for Use as Electrical Conductors
This standard is issued under the fixed designation B738; 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.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Classification
3.1 For the purposes of this specification, the following
1.1 This specification covers bare bunch-stranded and rope-
classifications have been assigned (Explanatory Note 2):
lay bunch-stranded conductors made from round copper wires
3.1.1 Type:
finer than No. 40 AWG with diameters less than 0.0031 in.
(.078 mm), either coated or uncoated with tin or silver, for use 3.1.1.1 Type B—Bunch-stranded conductors.
3.1.1.2 Type R—Rope-lay bunch-stranded conductors.
as electrical conductors. (Explanatory Note 1).
3.1.2 Class:
1.2 The values (SI units) for density and temperature are
3.1.2.1 Class R—Stranded conductors using wire 42 AWG
regarded as the standard. For all other properties the inch-
(0.0025).
pound values are to be regarded as standard, and the SI units
3.1.2.2 Class S—Stranded conductors using wire 44 AWG
may be approximate.
(0.0020).
3.1.2.3 Class T—Stranded conductors using wire 46 AWG
2. Referenced Documents
(0.00157).
2.1 ASTM Standards: 3.1.2.4 Class U—Stranded conductors using wire 48 AWG
B33Specification for Tin-Coated Soft or Annealed Copper (0.00124).
Wire for Electrical Purposes 3.1.2.5 Class V—Stranded conductors using wire 50 AWG
B49Specification for Copper Rod Drawing Stock for Elec-
(0.00099).
trical Purposes
3.2 Detailed information on Type B Conductors is found in
B172Specification for Rope-Lay-Stranded Copper Conduc-
Table 1 and Table 2. Detailed information on Type R Conduc-
torsHavingBunch-StrandedMembers,forElectricalCon-
tors is found in Table 3 and Table 2.
ductors
B174Specification for Bunch-Stranded Copper Conductors
4. Ordering Information
for Electrical Conductors
4.1 Orders for materials under this specification shall in-
B193Test Method for Resistivity of Electrical Conductor
clude the following information:
Materials
4.1.1 Quantity of each size, class, and type,
B258 Specification for Nominal Diameters and Cross-
4.1.2 Conductor size—circular-mil area, dc resistance (7.1)
SectionalAreasofAWGSizesofSolidRoundWiresUsed
or AWG (5.2.1),
as Electrical Conductors
4.1.3 Class and type (Section 3),
B298Specification for Silver-Coated Soft orAnnealed Cop-
4.1.4 Whether coated or uncoated; if coated, designate type
per Wire
of coating (6.1); if silver coated, the minimum thickness of
B354Terminology Relating to Uninsulated Metallic Electri-
silver (6.1.2), and whether tarnish protection is desired (11.3),
cal Conductors
4.1.5 Maximum length of lay (5.2.4), if required,
4.1.6 Temper (6.2),
4.1.7 Separators, if required (5.2.2),
This specification is under the jurisdiction of ASTM Committee B01 on
4.1.8 Package size (11.1),
Electrical Conductors and is the direct responsibility of Subcommittee B01.04 on
Conductors of Copper and Copper Alloys.
4.1.9 Specialpackagemarking,ifrequired(Section10),and
Current edition approved April 1, 2008. Published May 2008. Originally
4.1.10 Place of inspection (Section 9).
approved in 1984. Last previous edition approved in 2003 as B738–03. DOI:
10.1520/B0738-03R08.
4.2 In addition, Supplementary Requirements shall apply
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
onlywhenspecifiedbythepurchaserintheinquiry,contract,or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
purchase order for direct procurement by agencies of the U.S.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. Government.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B738−03 (2008)
TABLE 1 Classification of Type B Bunch-Stranded Conductors
6.1.2 Silver coating shall conform to the minimum thick-
A
Class Wire Diameter, in. Conductor Sizes, AWG ness requirements of the purchase document. Minimum thick-
R 0.0025 (No. 42 AWG) 24,26,28,30,32,34 ness shall be determined using the method for determining
S 0.0020 (No. 44 AWG) 26,28,30,32,34,36
plating thickness described in Specification B298.
T 0.00157 (No. 46 AWG) 28,30,32,34,36,38
6.1.3 The finished diameter and mass of the coated wires
U 0.00124 (No. 48 AWG) 30,32,34,36,38,40
V 0.00099 (No. 50 AWG) 32,34,36,38,40 used shall be substantially equal to those of the uncoated wires
A
of the same class.
Sufficientquantitiesofwiresofthesediametersshallbeusedtoformconductors
having cross-sectional areas approximately equal to the AWG conductor sizes
6.2 Temper—Unless otherwise specified, all coated conduc-
listed.
tors shall be furnished in the annealed temper. Uncoated
conductors may be furnished either annealed or unannealed as
ordered (see 4.1.6).
NOTE 1—The term unannealed as used in this specification means
5. Materials and Manufacture
cold-worked conductor as produced on commercial wire-drawing ma-
5.1 The material shall be copper of such quality and purity
chines.
that the finished product shall have the properties and charac-
6.3 Tensile Strength and Elongation—The stranded conduc-
teristics described in this specification. Material meeting the
tor, in its finished form, shall conform to the following:
requirements of Specification B49 is such a material.
Tensile Strength, min. Elongation, min,
5.2 Construction: Finished State psi MPa 10 in. %
Unannealed 40 000 275 .
5.2.1 Cross-SectionalArea—The cross-sectional area, num-
Annealed . . 10
ber, and diameter of wires for a variety of strand constructions
in general use are shown in Table 2.
7. Electrical Properties
5.2.2 Separators—If a separator is required to be furnished
7.1 DC Resistance—The dc resistance in Ω/1000 ft of the
with the conductor, it shall be specified by the purchaser at the
bunch-stranded conductor shall not exceed the appropriate
time of the order as to the requirements for the kind and
values specified in Table 5. The dc resistance inΩ/1000 ft of
thickness of material and its application details.
the rope-lay bunch-stranded conductor shall not exceed the
5.2.3 Joints:
appropriate values specified in Table 6 (Explanatory Note 3
5.2.3.1 Necessary joints in wires shall be made in accor-
and Note 4).
dance with accepted commercial practice.
5.2.3.2 Joints shall be so constructed and so disposed
8. Test Methods
throughout the conductor that the diameter or configuration of
8.1 Coating—Teststodetermineconformanceofthecoating
the completed conductor is not substantially affected, and that
totherequirementsofSpecificationB33orSpecificationB298
the flexibility of the completed conductor is not adversely
shall be performed on the individual wires before stranding
affected.
(see 6.1.1 to 6.1.3).
5.2.4 Lay:
5.2.4.1 Conductors of the same size and description fur- 8.2 Tensile Strength and Elongation:
nished on one order shall have the same lay. 8.2.1 Tests to determine conformance to the tensile strength
5.2.4.2 The direction of the lay of bunch-stranded conduc- and elongation requirements of 6.3 shall be made on the
tors shall be at the option of the manufacturer unless otherwise finished stranded conductor.
specified by the purchaser. 8.2.2 Determine tensile strength, T , expressed in pounds
s
5.2.4.3 Unless otherwise specified by the purchaser, the per square inch as follows:
length of the lay of bare or coated bunch-stranded conductors
L
T 5
shall conform to the requirements of Table 4.
s
A
5.2.4.4 Thedirectionofthelayoftheouterlayerofrope-lay
where:
stranded conductors shall be lefthand, unless otherwise speci-
L = maximum load on the stranded conductor during the
fied by the purchaser.
5.2.4.5 The length of the lay of the outer layer of rope-lay tension test (see Explanatory Note 5), lbs, and
A = original cross-sectional area of the stranded conductor,
stranded conductors shall be not less than 8 or more than 16
in. /in. (see 8.2).
times the outside diameter of the completed conductor. The
length of the lay of the wires composing the bunch-stranded
8.2.3 The original cross-sectional area of the stranded con-
members shall be not more than 30 times the diameter of the
ductor shall be considered to be the cross-sectional area of the
member.
individualwirecalculatedfromthenominalwirediameter(see
Table 5) multiplied by the number of wires in the stranded
6. Physical Properties
conductor (Explanatory Note 6).
6.1 WireCoating—When coated, the coating of the wires of 8.2.4 Determine the elongation of the specimen as the
the stranded conductor, before stranding, shall conform to the permanent increase in length, expressed in percent of the
requirements of 6.1.1 or 6.1.2. original length, due to the breaking of the specimen in tension,
6.1.1 Tin coating shall conform to the coating requirements by measurements made between the jaws of testing machine.
of Specification B33. The zero length shall be the distance between the jaws at the
B738−03 (2008)
A
TABLE 2 Construction Requirements of Bunch-Stranded and Rope-Lay Bunch-Stranded Conductors
CLASS R CLASS S CLASS T CLASS U CLASS V
Minimum Number Minimum Number Minimum Number Minimum Number Minimum Number
Nominal
Size, of Wires 0.0025 in. of Wires 0.0020 in. of Wires 0.00157 in. of Wires 0.00124 in. of Wires 0.00099 in.
Area,
AWG in Diameter in Diameter in Diameter in Diameter in Diameter
cmil
(No. 42 AWG) (No. 44 AWG) (No. 46 AWG) (No. 48 AWG) (No. 50 AWG)
B C
Type B Type R Type B Type R Type B Type R Type B Type R Type B Type R
2580 16 . . . 665 . . . . . .
1620 18 . . . 413 . . . . . .
1020 20 . 168 . 259 . . . . . .
640 22 . 105 . 168 . . . . . .
404 24 65 . . 105 . 168 . . . .
253 26 41 . 65 . . 105 . 168 . .
159 28 26 . 40 . 65 . . 105 . 168
100 30 16 . 25 . 40 . 65 . . 105
64 32 10 . 16 . 25 . 40 . 65 .
40 34 7 . 10 . 16 . 25 . 40 .
25 36 . . 7 . 10 . 16 . 25 .
16 38 . . . . 7 . 10 . 16 .
10 40 . . . . . . 7 . 10 .
A
This table shows a variety of strand constructions useful and generally adequate to meet the needs encountered. It is not intended that the constructions listed in this
tablebeexclusiveofotherconstructionsthatmayappeardurableincertainapplicationsemployingthesamenumberofwires.Theconstructionsshowninthistableprovide
for a finished, noncovered, stranded conductor approximately of the area indicated. When specified by the purchaser, usually to provide additional area to compensate
for draw-down during subsequent processing, the number or size of wires composing the uncovered conductor may be increased as required.
B
Type B Bunch-Stranded Conductors.
C
Type R Rope-Lay Bunch-Stranded Conductors.
TABLE 3 Classification of Type R Rope-Lay Bunch-Stranded
tionandawhitebackgroundshallbeperformedonaconductor
A
Conductors
sample taken from the top of the supplied spool. The sample
B
Class Wire Diameter, in. Conductor Sizes, AWG
shall be a minimum of 12 in. (30 cm) in length. The outer
R 0.0025 (No. 42 AWG) 20,22
surface of all stranded constructions shall be examined.
S 0.0020 (No. 44 AWG) 16,18,20,22,24
Detection of excessive exposed base metal due to the
T 0.00157 (No. 46 AWG) 24,26
U 0.00124 (No. 48 AWG) 26,28
stranding process, such as indications along one side of the
V 0.00099 (No. 50 AWG) 28,30
sample due to excessive localized abrasion during stranding,
A
Rope-lay bunch-stranded conductors 7 by bunch-stranded members.
constitutes rejection. Continuous lines or patterns of exposed
B
Sufficientquantitiesofwiresofthesediametersshallbeusedtoformconductors
base metals constitute rejection. Small, random point failures
having cross-sectional areas approximately equal to the AWG conductor sizes
listed. shall not be cause for rejection.
9. Inspection
start of the tension test, and shall be as near 10 in. (250 mm)
9.1 Unless otherwise specified in the contract or purchase
as practicable. The final length shall be the distance between
order, the manufacturer shall be responsible for the perfor-
the jaws at the time of rupture. The fracture shall be between
mance of all inspection and test requirements specified.
the jaws of the testing machine and not closer than 1 in. (25
9.2 All inspection and tests shall be made at the place of
mm) to either jaw.
manufacture unless otherwise especially agreed upon between
8.3 Electrical—Tests to determine conformance to the elec-
the manufacturer and the purchaser at the time of purchase.
trical resistance requirements of 7.1 shall be made on the
9.3 Themanufacturershallaffordtheinspectorrepresenting
finished stranded conductor in accordance with Test Method
the purchaser all reasonable manufacturer’s facilities to satisfy
B193 (Explanatory Note 3).
himthatthematerialisbeingfurnishedinaccordancewiththis
8.4 Other Requirements—For the purpose of calculating
specification.
mass, cross-sectional area, and so forth, the density of the
3 3
coated copper shall be taken as 8.89 g/cm (0.32117 lb/in.)at
10. Product Marking
20°C (Explanatory Note 5).
10.1 The net mass, length (or lengths, and number of
8.5 Examination for Workmanship of Finished Uninsulated
lengths, if more than one length is included in the package),
StrandedConductor—Avisualinspectionwiththeunaidedeye
size designation, type of conductor, purchase order number,
shall be performed on the outer layer of the conductor on the
and any other marks required by the purchase order shall be
supplied package. Use a white card (as a background) to
marked on a tag attached to the reel and, optionally, to the end
ascertain if any base metal is exposed through a break in the
of the conductor inside of the package. The same information,
coating. Detection of any base metal constitutes rejection.
together with the manufacturer’s serial number, if any, and all
8.6 Examination for Workmanship of Finished Uninsulated shipping marks required by the purchaser, shall appear on the
outside of each package.
Stranded Conductor—Avisual inspection with 10× magnifica-
B738−03 (2008)
TABLE 4 Maximum Length of Lay for Bunch-Stranded Conductors
Nominal Diameter Nominal Area Maximum Length of Lay
Size, AWG
in. (mm) cmil (mm ) in. (mm)
24 0.024 (0.61) 404 (0.20) 0.70 (18)
26 0.019 (0.48) 253 (0.13) 0.60 (15)
28 0.015 (0.38) 159 (0.081) 0.50 (13)
30 0.012 (0.30) 100 (0.051) 0.40 (10)
...

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:B 738–98 Designation: B 738 – 03 (Reapproved 2008)
Standard Specification for
Fine-Wire Bunch-Stranded and Rope-Lay Bunch-Stranded
Copper Conductors for Use as Electrical Conductors
This standard is issued under the fixed designation B 738; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This specification covers bare bunch-stranded and rope-lay bunch-stranded conductors made from round copper wires finer
than No. 40AWG with diameters less than 0.0031 in. (.078 mm), either coated or uncoated with tin or silver, for use as electrical
conductors. (Explanatory Note 1).
1.2 Thevalues(SIunits)fordensityandtemperatureareregardedasthestandard.Forallotherpropertiestheinch-poundvalues
are to be regarded as standard, and the SI units may be approximate.
2. Referenced Documents
2.1 ASTM Standards:
B 33 Specification for Tinned Soft or Annealed Copper Wire for Electrical Purposes
B 49 Specification for Copper Redraw Rod Drawing Stock for Electrical Purposes
B 172 Specification for Rope-Lay-Stranded Copper Conductors Having Bunch-Stranded Members, for Electrical Conductors
B 174 Specification for Bunch-Stranded Copper Conductors for Electrical Conductors
B 193 Test Method for Resistivity of Electrical Conductor Materials
B 258 Specification for Standard Nominal Diameters and Cross-SectionalAreas ofAWG Sizes of Solid Round Wires Used as
Electrical Conductors
B 298 Specification for Silver-Coated Soft or Annealed Copper Wire
B 354 Terminology Relating to Uninsulated Metallic Electrical Conductors
3. Classification
3.1 For the purposes of this specification, the following classifications have been assigned (Explanatory Note 2):
3.1.1 Type:
3.1.1.1 Type B—Bunch-stranded conductors.
3.1.1.2 Type R—Rope-lay bunch-stranded conductors.
3.1.2 Class:
3.1.2.1 Class R—Stranded conductors using wire 42 AWG (0.0025).
3.1.2.2 Class S—Stranded conductors using wire 44 AWG (0.0020).
3.1.2.3 Class T—Stranded conductors using wire 46 AWG (0.00157).
3.1.2.4 Class U—Stranded conductors using wire 48 AWG (0.00124).
3.1.2.5 Class V—Stranded conductors using wire 50 AWG (0.00099).
3.2 Detailed information on Type B Conductors is found in Table 1 and Table 2. Detailed information on Type R Conductors
is found in Table 3 and Table 2.
4. Ordering Information
4.1 Orders for materials under this specification shall include the following information:
4.1.1 Quantity of each size, class, and type,
4.1.2 Conductor size—circular-mil area, d-cdc resistance (7.1) or AWG (5.2.1),
4.1.3 Class and type (Section 3),
This specification is under the jurisdiction ofASTM Committee B-1B01 on Electrical Conductors and is the direct responsibility of Subcommittee B01.04 on Conductors
of Copper and Copper Alloys.
Current edition approved March 10, 1998.April 1, 2008. Published September 1998.May 2008. Originally published as B738–84.approved in 1984. Last previous edition
approved in 2003 as B 738 – 903.
Annual Book of ASTM Standards, Vol 02.03.
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at [e-mail]. ForAnnualBookofASTMStandards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
B 738 – 03 (2008)
TABLE 1 Classification of Type B Bunch-Stranded Conductors
A
Class Wire Diameter, in. Conductor Sizes, AWG
R 0.0025 (No. 42 AWG) 24,26,28,30,32,34
S 0.0020 (No. 44 AWG) 26,28,30,32,34,36
T 0.00157 (No. 46 AWG) 28,30,32,34,36,38
U 0.00124 (No. 48 AWG) 30,32,34,36,38,40
V 0.00099 (No. 50 AWG) 32,34,36,38,40
A
Sufficient quantities of wires of these diameters shall be used to form
conductors having cross-sectional areas approximately equal to theAWG conduc-
tor sizes listed.
A
TABLE 2 Construction Requirements of Bunch-Stranded and Rope-Lay Bunch-Stranded Conductors
CLASS R CLASS S CLASS T CLASS U CLASS V
Minimum Number Minimum Number Minimum Number Minimum Number Minimum Number
Nominal
Size, of Wires 0.0025 in. of Wires 0.0020 in. of Wires 0.00157 in. of Wires 0.00124 in. of Wires 0.00099 in.
Area,
AWG in Diameter in Diameter in Diameter in Diameter in Diameter
cmil
(No. 42 AWG) (No. 44 AWG) (No. 46 AWG) (No. 48 AWG) (No. 50 AWG)
B C
Type B Type R Type B Type R Type B Type R Type B Type R Type B Type R
2580 16 . . . 665 . . . . . .
1620 18 . . . 413 . . . . . .
1020 20 . 168 . 259 . . . . . .
640 22 . 105 . 168 . . . . . .
404 24 65 . . 105 . 168 . . . .
253 26 41 . 65 . . 105 . 168 . .
159 28 26 . 40 . 65 . . 105 . 168
100 30 16 . 25 . 40 . 65 . . 105
64 32 10 . 16 . 25 . 40 . 65 .
40 34 7 . 10 . 16 . 25 . 40 .
25 36 . . 7 . 10 . 16 . 25 .
16 38 . . . . 7 . 10 . 16 .
10 40 . . . . . . 7 . 10 .
A
This table shows a variety of strand constructions useful and generally adequate to meet the needs encountered. It is not intended that the constructions listed in this
tablebeexclusiveofotherconstructionsthatmayappeardurableincertainapplicationsemployingthesamenumberofwires.Theconstructionsshowninthistableprovide
for a finished, noncovered, stranded conductor approximately of the area indicated. When specified by the purchaser, usually to provide additional area to compensate
for draw-down during subsequent processing, the number or size of wires composing the uncovered conductor may be increased as required.
B
Type B Bunch-Stranded Conductors.
C
Type R Rope-Lay Bunch-Stranded Conductors.
TABLE 3 Classification of Type R Rope-Lay Bunch-Stranded
A
Conductors
B
Class Wire Diameter, in. Conductor Sizes, AWG
R 0.0025 (No. 42 AWG) 20,22
S 0.0020 (No. 44 AWG) 16,18,20,22,24
T 0.00157 (No. 46 AWG) 24,26
U 0.00124 (No. 48 AWG) 26,28
V 0.00099 (No. 50 AWG) 28,30
A
Rope-lay bunch-stranded conductors 7 by bunch-stranded members.
B
Sufficient quantities of wires of these diameters shall be used to form
conductors having cross-sectional areas approximately equal to theAWG conduc-
tor sizes listed.
4.1.4 Whether coated or uncoated; if coated, designate type of coating (6.1); if silver coated, the minimum thickness of silver
(6.1.2), and whether tarnish protection is desired (11.3),
4.1.5 Maximum length of lay (5.2.4), if required,
4.1.6 Temper (6.2),
4.1.7 Separators, if required (5.2.2),
4.1.8 Package size (11.1),
4.1.9 Special package marking, if required (Section 10), and
4.1.10 Place of inspection (Section 9).
4.2 In addition, Supplementary Requirements shall apply only when specified by the purchaser in the inquiry, contract, or
purchase order for direct procurement by agencies of the U.S. Government.
5. Materials and Manufacture
5.1 The material shall be copper of such quality and purity that the finished product shall have the properties and characteristics
described in this specification. Material meeting the requirements of Specification B 49 is such a material.
5.2 Construction:
B 738 – 03 (2008)
5.2.1 Cross-Sectional Area—The cross-sectional area, number, and diameter of wires for a variety of strand constructions in
general use are shown in Table 2.
5.2.2 Separators—If a separator is required to be furnished with the conductor, it shall be specified by the purchaser at the time
of the order as to the requirements for the kind and thickness of material and its application details.
5.2.3 Joints:
5.2.3.1 Necessary joints in wires shall be made in accordance with accepted commercial practice.
5.2.3.2 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 that the flexibility of the completed conductor is not adversely affected.
5.2.4 Lay:
5.2.4.1 Conductors of the same size and description furnished on one order shall have the same lay.
5.2.4.2 The direction of the lay of bunch-stranded conductors shall be at the option of the manufacturer unless otherwise
specified by the purchaser.
5.2.4.3 Unless otherwise specified by the purchaser, the length of the lay of bare or coated bunch-stranded conductors shall
conform to the requirements of Table 4.
5.2.4.4 The direction of the lay of the outer layer of rope-lay stranded conductors shall be lefthand, unless otherwise specified
by the purchaser.
5.2.4.5 The length of the lay of the outer layer of rope-lay stranded conductors shall be not less than 8 or more than 16 times
the outside diameter of the completed conductor. The length of the lay of the wires composing the bunch-stranded members shall
be not more than 30 times the diameter of the member.
6. Physical Properties
6.1 Wire Coating—When coated, the coating of the wires of the stranded conductor, before stranding, shall conform to the
requirements of 6.1.1 or 6.1.2.
6.1.1 Tin coating shall conform to the coating requirements of Specification B 33.
6.1.2 Silver coating shall conform to the minimum thickness requirements of the purchase document. Minimum thickness shall
be determined using the method for determining plating thickness described in Specification B 298.
6.1.3 The finished diameter and mass of the coated wires used shall be substantially equal to those of the uncoated wires of the
same class.
6.2 Temper—Unless otherwise specified, all coated conductors shall be furnished in the annealed temper. Uncoated conductors
may be furnished either annealed or unannealed as ordered (see 4.1.6).
NOTE 1—The term unannealed as used in this specification means cold-worked conductor as produced on commercial wire-drawing machines.
6.3 Tensile Strength and Elongation— The stranded conductor, in its finished form, shall conform to the following:
Tensile Strength, min. Elongation, min,
Finished State psi MPa 10 in. %
Unannealed 40 000 275 .
Annealed . . 10
7. Electrical Properties
7.1 D-CDC Resistance—The d-cdc resistance in V/1000 ft of the bunch-stranded conductor shall not exceed the appropriate
values specified in Table 5. The d-cdc resistance in V/1000 ft of the rope-lay bunch-stranded conductor shall not exceed the
appropriate values specified in Table 6 (Explanatory Note 3 and Note 4).
8. Test Methods
8.1 Coating—Tests to determine conformance of the coating to the requirements of Specification B 33 or Specification B 298
shall be performed on the individual wires before stranding (see 6.1.1 to 6.1.3).
8.2 Tensile Strength and Elongation :
TABLE 4 Maximum Length of Lay for Bunch-Stranded Conductors
Nominal Diameter Nominal Area Maximum Length of Lay
Size, AWG
in. (mm) cmil (mm ) in. (mm)
24 0.024 (0.61) 404 (0.20) 0.70 (18)
26 0.019 (0.48) 253 (0.13) 0.60 (15)
28 0.015 (0.38) 159 (0.081) 0.50 (13)
30 0.012 (0.30) 100 (0.051) 0.40 (10)
32 0.009 (0.23) 64 (0.032) 0.30 (7.6)
34 0.007 (0.18) 40 (0.020) 0.25 (6.4)
36 0.006 (0.15) 25 (0.013) 0.20 (5.1)
38 0.005 (0.13) 16 (0.0081) 0.15 (3.8)
40 0.004 (0.10) 10 (0.0051) 0.13 (3.3)
B 738 – 03 (2008)
TABLE 5 D-C Ohmic Resistance Per 1000 Ft. of Type B Bunch-Stranded Conductors
A B
Conductor Construction D-C Resistance at 20°C, V/1000 ft, max.
Calculated Total
Size Designations Cross-Sectional
Number of Nominal Diameter Annealed Bare or Annealed Tin Unannealed
C Area cmil D E
Wires of Each Wire, in. Silver Coated Coated Bare
24-65 65 0.0025 406 28.3 30.4 29.4
26-41 41 0.0025 256 44.9 48.2 46.7
26-65 65 0.0020 260 45.2 48.5 47.0
28-26 26 0.0025 163 70.8 76.0 73.6
28-40 40 0.0020 160 73.5 78.9 76.4
28-65 65 0.00157 160 71.8 . 74.6
30-16 16 0.0025 100 115.0 123.4 119.6
30-25 25 0.0020 100 117.5 126.2 122.2
30-40 40 0.00157 98.6 116.6 . 121.3
30-65 65 0.00124 99.9 115.0 . 119.6
C C
32-10 10 0.0025 62.5 184.0 197.5 191.3
32-16 16 0.0020 64 183.7 197.2 191.0
C C
32-25 25 0.00157 61.6 186.6 . 194.0
C C
32-40 40 0.00124 61.5 187.0 . 194.4
32-65 65 0.00099 63.7 180.5 . 187.7
34-7 7 0.0025 43.8 262.8 281.8 273.3
34-10 10 0.0020 40 293.8 315.5 305.6
34-16 16 0.00157 39.4 291.6 . 303.2
C C
34-25 25 0.00124 38.4 299.1 . 311.1
34-40 40 0.00099 39.2 293.3 . 305.0
36-7 7 0.0020 28 419.8 450.6 436.5
36-10 10 0.00157 24.6 466.5 . 485.1
36-16 16 0.00124 24.6 467.4 . 486.0
36-25 25 0.00099 24.5 469.3 . 488.0
38-7 7 0.00157 17.3 666.4 . 693.0
C C
38-10 10 0.00124 15.4 747.8 . 777.7
38-16 16 0.00099 15.7 733.2 . 762.5
40-7 7 0.00124 10.8 1068.3 . 1111.0
40-10 10 0.00099 9.8 1173.2 . 1220.0
A
See Table 2 for construction requirements or bunch-stranded conductors.
B
See Explanatory Note 4.
C
Bunch.
D
Thecross-sectionalareasoftheseconductor-sizedesignationsdeviatebymorethan2 %fromthenominalareasofthestandardAWGsizesasdefinedinSpecification
B 258.
E
Tin-coated wire is not available at this time on wire diameters smaller than .0020 (44 AWG).
TABLE 6 D-C Ohmic Resistance Per 1000 Ft. of Type R Rope-Lay Bunch-Stranded Conductor
A B
Conductor Construction D-C Resistance of 20°C, Ohms/1000 ft. max.
Calculated Total
Size Designation Cross-Sectional
Number of Nominal Diameter Annealed Bare or Annealed Tin Unannealed
C B D
Area cmil
Wires of Each Wire, in. Silver Coated Coated Bare
16-665 665 0.0020 2660 4.51 4.84 4.69
18-413 413 0.0020 1652 7.25 7.79 7.54
20-168 168 0.0025 1050 11.2 12.0 11.6
20-259 259 0.0020 1036 11.6 12.4 12.0
22-105 105 0.0025 656 17.9 19.2 18.6
22-168 168 0.0020 672 17.8 19.1 18.5
24-105 105 0.0020 420 28.5 30.6 29.7
24-168 168 0.00157 414 28.3 . 29.4
26-105 105 0.00157 259 45.3 . 47.1
26-168 168 0.00124 258 45.4 . 47.2
28-105 105 0.00124 161 72.6 . 75.5
28-168 168 0.00099 165 71.2 . 74.0
30-105 105 0.00099 103 113.9 . 118.5
A
See Table 2 Construction Requirements of Rope-Lay Bunch-Stranded Conductors.
B
See Explanatory Note 3.
C
Seven Member Ropes.
D
Tin coated wire is not available at this time on wire diameters smaller than .0020 (44 AWG).
8.2.1 Tests to determine conformance to the tensile strength and elongation requirements of 6.3 shall be made on the finished
stranded conductor.
8.2.2 Determine tensile strength, T , expressed in pounds per square inch as follows:
s
L
T 5
s
A
where:
L = maximum load on the stranded conductor during the tension test (see Exp
...