1,but which is less than that of the next larger size,the
requirements of the next larger size shall apply.
7.4Determine the elongation of the wire as the permanent
increa in length due to the breaking of the wire in tension,
measured between gage marks placed originally 10in.(254
mm)apart upon the test specimen (Explanatory Note 4).
7.5If any part of the fracture takes place outside the gage
marks or in the jaws of the testing machine,or if an examina-
tion of the specimen indicates a flaw,the value obtained may
not be reprentative of the material.In such cas the test may
be discarded and a new test made.
7.6Retests —If,upon testing a sample from any coil or
spool of wire,the results do not conform to the requirements
prescribed in Table 1,two additional samples shall be tested
and the average of the three tests shall determine the accep-
tance or rejection of the coil or spool.
8.Resistivity
8.1Electrical resistivity shall be determined on reprenta-
tive samples by resistance measurements (Explanatory Note 5
and Note 6).At a temperature of 20°C the resistivity shall not
exceed the following values:
Nominal Diameter,in.
Resistivity at 20°C,V ·lb/mile 2V ·g/m 20.460to 0.325(11.684to 8.255mm),incl
896.150.15695Under 0.325to 0.0403(8.255to 1.024mm),incl 905.440.15858
8.2Tests to determine conformance to the electrical resis-
tance requirements shall be made in accordance with Test
Method B 193.
9.Joints
9.1No joints shall be made in the completed wire (Explana-
tory Note 7).Joints in wire and rods,prior to final drawing,
shall be made in accordance with the best commercial practice
and shall conform to the requirements prescribed in 7.2.
10.Inspection
10.1Unless otherwi specified in the contract or purcha order,the manufacturer shall be responsible for the perfor-mance of all inspection and test requirements specified (Ex-planatory Note 8).10.2All inspections and tests shall be made at the place of manufacture unless otherwi especially agreed to between the manufacturer and the purchar at the time of the purcha.10.3The manufacturer shall afford the inspector reprent-ing the purchar all reasonable manufacturer’s facilities to satisfy that the material is being furnished in accordance with this specification.10.4Unless otherwi agreed upon between the purchar and the manufacturer,conformance of the wire to the various requirements listed in this specification shall be determined on samples taken from each lot of wire prented for acceptance.10.5The manufacturer shall,if requested prior to inspec-tion,certify that all wire in the lot was made under such conditions that the product as a whole conforms to the requirements of this specification as determined by regularly made and recorded tests.10.6Inspection and Testing Terms :10.6.1Lot —A lot is any amount of wire of one type and size prented for acceptance at one time;such amount,however,not to exceed 100000lb or 45000kg (Explanatory Note 9).10.6.2Sample —A sample is a quantity of prod
uction units (coils,reels,etc.)lected at random from the lot for the purpo of determining conformance of the lot to the require-ments of this specification.10.6.3Specimen —A specimen is a length of wire removed for test purpos from any individual production unit of the sample.10.7Sample Size —The number of production units in a sample (Explanatory Note 8)shall be as follows:10.7.1For tension,elongation,and resistivity determina-tions,the sample shall consist of four production units.From each unit,one test specimen of sufficient length shall be removed for the performance of the required tests.
TABLE 1Tensile Requirements
Diameter
Area at 20°C Tensile Strength Elongation,min,%in 10-in.( cmil in.2mm 2
psi MPa Min
Max Min Max 0.4600
11.6842116000.1662107.04200049000290340 3.80.4096
10.4041678000.131885.04300050000295345 3.60.3648
9.2661331000.104567.44400051000305350 3.20.3249
8.2521056000.0829153.54500052000310360 3.00.2893
7.348836900.0657342.44600053000315365 2.80.2576
6.543663600.0521233.64700054000325370 2.50.2294
5.827526200.041332
6.74800055000330380 2.20.2043
5.189417400.0327821.24833055330335380 1.90.1819
4.620330900.0259916.84866055660335385 1.70.1620
4.115262400.0206113.34900056000340385 1.50.1443
3.665208200.0163510.54933056330340390 1.40.1285
3.264165100.012978.374966056660340390 1.30.1144
2.906130900.01028 6.635000057000345395 1.30.1019
2.588103800.008155 5.265033057330345395 1.20.0907
2.30482300.00646 4.175066057600350400 1.20.0808
2.05265300.00513
3.315100058000350400 1.10.0720
1.82951800.00407
2.635133058330355400 1.10.0641
1.62841100.00323
2.085166058660355405 1.00.0571
1.45032600.00256 1.655200059000360405 1.00.0508
1.29025800.00203 1.315233059330360410 1.00.0453
1.15120500.00161 1.045266059660365410 1.00.0403 1.02416200.001280.8235300060000365415
1.0
10.7.2For dimensional measurements,the sample shall
consist of a quantity of production units shown in Table 2
under the heading “First Sample.”
10.7.3For surface-finish inspection and for packaging in-
spection (when specified by the purchar at the time of placing
the order)the sample shall consist of a quantity of production
units shown in Table 3.
11.Packaging and Shipping
11.1Package sizes shall be agreed upon between the manu-
facturer and the purchar in the placing of individual orders.
11.2The wire shall be protected against damage in ordinary
handling and shipping.12.Keywords 12.1copper wire;medium-hard copper wire;round copper electrical wire;round copper wire
EXPLANATORY NOTES
N OTE 1—Medium-hard drawn wire approaches hard-drawn wire in its
characteristics,but from the very nature of the product,exact uniformity
in tensile strength cannot be obtained.Hence it has been necessary to
establish a range of tensile strengths within which standard medium-hard-
drawn wire may be expected to be found.
N OTE 2—The values of the wire diameters in Table 1are given to the
nearest 0.0001in.(0.001mm)and correspond to the standard sizes given
in Specification B 258.The u of gage numbers to specify wire sizes is
not recognized in this specification becau of the possibility of confusion.
An excellent discussion of wire gages and related subjects is contained in
NBS Handbook 100.
N OTE 3—Other tests than tho provided in this specification have been
considered at various times,such as twist tests,wrap tests,tests for elastic
limit,etc.It is the opinion of the committee that twist and wrap tests on
medium-hard-drawn wire do not rve a uful purpo and should be
regarded as undesirable,as well as inconclusive as to results and
significance.Tests for values of elastic limit are likewi indefinite as to
results.Tests to determine elastic properties of medium-hard-drawn wire
from which wire stringing and sagging data may be compiled are
considered to be outside the scope of the acceptance tests contemplated in
this specification.
N OTE 4—It is known that the rate of loading during tension testing of
copper affects the performance of the sample to a greater or lesr extent,
depending upon many factors.In general,tested values of tensile strength
are incread and tested values of elongation are reduced with increa of
speed of the moving head of the testing machine.The effects are
pronounced when the speed of the moving head is excessive in the testing
of medium-hard-drawn wires.It is suggested that tests be made at speeds
of moving head that,under no-load conditions,are not greater than 3in.
(75mm)/min,but in no ca at a speed greater than that at which correct
readings can be made.
N OTE 5—“Resistivity”is ud in place of “percentage conductivity.”
The value of 0.15328V ·g/m 2at 20°C is the international standard for the resistivity of annealed copper equal to 100%conductivity.This term means that a wire 1m in length and weighing 1g would have a resistance of 0.15328V .This is equivalent to a resistivity value of 875.20V ·lb/mile 2,which signifies the resistance of a wire 1mile in length weighing 1lb.It is also equivalent,for example,to 1.7241µV /cm of length of a bar 1cm 2in cross ction.A complete discussion of this subject is contained in NBS Handbook 100.Relationships that may be uful in connection with the values of resistivity prescribed in this specification are as in Table 4,each column containing equivalent expressions,at 20°C.N OTE 6—The value of density of copper is in accordance with the International Annealed Copper Standard.The corresponding value at 0°C is 8.90g/cm 3(0.32150lb/in.3).As pointe
d out in the discussion of this subject in NBS Handbook 100,there is no appreciable difference in values of density of medium-hard-drawn and annealed copper wire.N OTE 7—Mechanical joints made during inspection at the request of the purchar are permissible if agreed upon at the time of placing the order.N OTE 8—Cumulative results cured on the product of a single manu-facturer,indicating continued conformance to the criteria,are necessary to ensure an over-all product meeting the requirements of this specification.The sample sizes and conformance criteria given for the various charac-teristics are applicable only to lots produced under the conditions.TABLE 2Sampling for Dimensional Measurements
Number of Units
in Lot
First Sample Second Sample Number of Units in Sample,n 1Allowable Number of Defects in First Sample,c 1Number of Units in Sample,n 2n 1plus n 2Allowable Number of Defects in Both Samples,c 21to 14,incl
.15to 50,incl
<.51to 100,incl
19023421101to 200,incl
24046702201to 400,incl
290761053401to 800,incl
3301121454Over 8003401161504
TABLE 3Sampling for Surface Finish and Packaging Inspection
Number of Units in Lot Number of Units in Sample,n Allowable Number of Defective Units,c 1to 30,incl all 031to 50,incl 30051to 100,incl 370101to 200,incl 400201to 300,incl 701301to 500,incl 1002501to 800,incl 1303Over 8001554TABLE 4Resistivity Relationships Conductivity at 20°C,%100.0097.6696.66V ·lb/mile 2875.20896.15905.44V ·g/m 20.153280.156940.15857V ·cmil/ft 10.37110.61910.729V ·mm 2/m 0.0172410.0176540.017837µV ·in.0.678790.695040.70224µV ·cm 1.7241 1.7654
1.7837
N OTE9—A lot should compri material taken from a product regularly meeting the requirements of this specification.Inspection of individual lots of less than5000lb or2270kg of wire cannot be justified economically.For small lots of5000lb or less,or2270kg or less,the purchar may agree to the manufacturer’s regular inspection of the product as a whole as evidence of acceptability of such small lots.
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