ASTM B267-07(2013)
(Specification)Standard Specification for Wire for Use In Wire-Wound Resistors
Standard Specification for Wire for Use In Wire-Wound Resistors
ABSTRACT
This specification covers round wires and ribbons with controlled electrical properties made from magnetic and nonmagnetic class 1a-11 alloys. The wires and ribbons, which may have insulated coverings or enamel coatings, are recommended for use in wire-wound resistance units like precision resistors and other similar applications, but not for use as electrical heating elements. Each bare wire should conform to the requirements for nominal resistivity, elongation, thermal electromotive force with respect to copper, and the temperature coefficient of resistance contained in this specification. The nominal resistance per unit length for a round wire is calculated from the nominal resistivity and nominal cross-sectional area.
SCOPE
1.1 This specification covers round wire and ribbon with controlled electrical properties for use in wire-wound resistance units and similar applications, but not for use as electrical heating elements.
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.
1.3 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 become familiar with all hazards including those identified in the appropriate Material Safety Data Sheet (MSDS) for this product/material as provided by the manufacturer, to establish appropriate safety and health practices, and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
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Designation:B267 −07 (Reapproved 2013)
Standard Specification for
Wire for Use In Wire-Wound Resistors
This standard is issued under the fixed designation B267; 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 4. Alloy Classes
1.1 This specification covers round wire and ribbon with 4.1 Fifteenclassesofalloysarecoveredbythisspecification
controlled electrical properties for use in wire-wound resis- as listed in Table 1.
tanceunitsandsimilarapplications,butnotforuseaselectrical
heating elements.
5. Elongation
1.2 The values stated in inch-pound units are to be regarded
5.1 The wire shall conform to the requirements for elonga-
as standard. The values given in parentheses are mathematical
tionasprescribedinTable1,whentestedona10-in.(254-mm)
conversions to SI units that are provided for information only
length.
and are not considered standard.
6. Resistivity
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
6.1 The bare wire shall conform to the requirements for
responsibility of the user of this standard to become familiar
nominal resistivity as prescribed in Table 1.
with all hazards including those identified in the appropriate
6.2 Actualresistivityshallnotvaryfromnominalresistivity
Material Safety Data Sheet (MSDS) for this product/material
by more than 65% for Alloy Classes 1 to 4 inclusive, and
as provided by the manufacturer, to establish appropriate
610% for Alloy Classes 5 to 11 inclusive.
safety and health practices, and determine the applicability of
regulatory limitations prior to use.
7. Nominal Electrical Resistance per Unit Length
2. Referenced Documents
7.1 The nominal resistance per unit length for round wire
2.1 ASTM Standards:
shallbecalculatedfromthenominalresistivityandthenominal
B63Test Method for Resistivity of Metallically Conducting
cross-sectional area.
Resistance and Contact Materials
NOTE 1—When ribbon or flat wire is produced by rolling from round
B77Test Method for Thermoelectric Power of Electrical-
wire, the cross section departs from that of a true rectangle by an amount
Resistance Alloys
depending on the width-to-thickness ratio and the specific manufacturing
B84Test Method for Temperature-Resistance Constants of practice. The conventional formula for computing ohms per foot and feet
perpoundistoconsiderthecrosssectionas17%lessthanatruerectangle
Alloy Wires for Precision Resistors
when width is more than 15 times the thickness and 6% less than a true
rectangle in other cases. This is not valid in view of modern rolling
3. Significance and Use
equipment and practices, but still is widely used as a basis of description.
3.1 This specification on wire and ribbon contains the
Ribbonactuallyismadetoaspecifiedresistanceperfoot,andnotolerance
generic chemistry and requirements for resistivity, temperature isspecifiedforthickness.Analternativeandacloserapproximationwould
be that for ribbon rolled round wire, the electrical resistance would be
coefficient of resistance, thermal emf versus copper resistance
calculated on a cross 6% less than a true rectangle.
tolerances, and mechanical properties of bare wire, as well as
thewireenamelsandinsulationsofalloysnormallyusedinthe
8. Temperature Coefficient of Resistance
manufacture of wound resistors.
8.1 The change in resistance with change in temperature,
expressed as the mean temperature coefficient of resistance
This specification is under the jurisdiction of ASTM Committee B02 on
Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee basedonthereferencetemperatureof25°C,shallbewithinthe
B02.10 on Thermostat Metals and Electrical Resistance Heating Materials.
limits specified in Table 1, Columns 4 and 6, over the
Current edition approved May 1, 2013. Published May 2013. Originally
corresponding temperature ranges specified in Columns 5 and
approved in 1952. Last previous edition approved in 2007 as B267– 07. DOI:
7. The mean temperature coefficient of resistance referred to
10.1520/B0267-07R13.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 25°C is defined as the slope of a chord of an arc. This slope is
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
determined from the following equation:
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. α 5 ∆R/R ∆T 310
~ !
m 25
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B267−07 (2013)
TABLE 1 Classes of Alloys and Requirements
Mean Temperature Coefficient of Resistance, α ppm for Maximum Thermal emf
m
Elongation in 10 in., min, %
B
°C Over Temperature Range,∆ T versus Copper, mV/°C
Resistivity,
Alloy Alloy Composition,
Over 0.002 to
0.0009
Ω·cmil/ft
A
Class approximate, % D
Temperature 0.002 0.001
in. in
(µΩ·m)
∆T α ∆T mV/°C
m C
D D
Range, ∆ T Diameter
in. in in. in
and Finer
Diameter Diameter
12 3 4 5 6 7 8 9 10 11 12
1a nickel base, nonmagnetic 800 (1.330) 0, ±20 +25 to −55 0, ±20 +25 to +105 +0.003 −65 to +250 10 5 3
1b nickel base, nonmagnetic 800 (1.330) 0, ±10 +25 to −55 0, ±10 +25 to +105 +0.003 −65 to +150 10 5 3
1c nickel base, nonmagnetic 800 (1.330) 0, ±5 +25 to −55 0, ±5 +25 to +105 +0.003 −65 to +150 10 5 3
2a iron base, magnetic 800 (1.330) 0, ±20 +25 to −55 0, ±20 +25 to +105 −0.004 −65 to +200 10 5 3
2b iron base, magnetic 800 (1.330) 0, ±10 +25 to −55 0, ±10 +25 to +105 −0.004 −65 to +150 10 5 3
3a 80 nickel, 20 chromium 650 (1.081) +80, ±20 +25 to −55 +80, ±20 +25 to +105 +0.006 −65 to +250 15 5 3
3b 80 nickel, 20 chromium, 675 (1.122) +60, ±20 +25 to −55 +60, ±20 +25 to +105 +0.006 −65 to +250 15 5 3
stabilized
4 60 nickel, 16 chromium, 675 (1.122) +140, ±30 +25 to −55 +140, ±30 +25 to +105 +0.002 −65 to +200 15 5 3
balance iron
5a 55 copper, 45 nickel 300 (0.499) 0, ±20 +25 to −55 0, ±20 +25 to +105 −0.045 −65 to + 150 15 5 3
5b 55 copper, 45 nickel 300 (0.499) 0, ±40 +25 to −55 0, ±40 +25 to +105 −0.045 −65 to +150 15 5 3
EE EE
6 manganin type 290 (0.482) 0, ±15 0, ±15 −0.003 +15 to +35 15 5 3
7 77 copper, 23 nickel 180 (0.299) +180, ±30 +25 to −55 +180, ±30 +25 to +105 −0.037 −65 to +150 15 5 3
8 70 nickel, 30 iron 125 (0.199) +3600, ±400 +25 to −50 +4300, ±400 +25 to +104 −0.040 −50 to +100 15 5 3
9 90 copper, 10 nickel 90 (0.150) +450, ±50 +25 to −55 +450, ±50 +25 to +105 −0.026 −65 to +150 15 5 3
10 94 copper, 6 nickel 60 (0.100) +700, ±200 +25 to −55 +700, ±200 +25 to +105 −0.022 −65 to +150 15 5 3
11 98 copper, 2 nickel 30 (0.050) +1400, ±300 +25 to −55 +1400, ±300 +25 to +105 0.014 −65 to +150 15 5 3
A
Alloy Classes 1a to 8 inclusive are designed to provide controlled temperature coefficients. Values shown for other classes are for information only. All values are based
on a reference temperature of 25°C.
B
Alloy Classes 1a, 1b, 1c, 2a, 2b, 3a, 4, and 6 are designed to give a low emf versus copper. Values shown for other classes are for information only. Maximum indicates
the maximum deviation from zero and the plus or minus sign the polarity of the couple.
C
The maximum temperature values listed apply to the alloy wire only. Caution should be exercised pending knowledge of the maximum temperature of use for the coating
material involved.
D
If metric sizes are desired, 1 in. = 25.4 mm.
E
Alloy Class 6 (manganin type for resistors), has a temperature-resistance curve of parabolic shape with the maximum resistance normally located between 25 and 30°C.
m
Thus, Columns 5 and 7 cannot indicate 25°C as a limit butα may be expressed as a maximum of + 15 ppm for 15°C to the temperature of maximum resistance and a
maximum of − 15 ppm from the temperature of maximum resistance to 35°C. All of the information included in this note is based on measurements made in accordance
with Test Method B84.
where:
Form Permissible
Variation, ±%
α = mean temperature coefficient of resistance, ppm/°C,
m
Over 0.005 in. (0.127 mm) in diameter 5
Table 1, Columns 4 and 6,
0.002 to 0.005 in. (0.051 to 0.127 mm) in diameter, incl 8
∆ R = changeinresistanceovertemperaturerangeindicated
Under 0.002 in (0.051 mm) in diameter 10
in Table 1, Columns 5 and 7, Ribbon 5
R = resistance at 25°C,
10.2 ForAlloyClasses1to4inclusive,theactualresistance
∆T = temperature range indicated in Table 1, Columns 5
of any 1-ft length of wire in one spool or coil shall not vary by
and 7.
more than 3% from the actual resistance of any other 1 ft of
wire in the same spool or coil.
8.2 ForAlloyClasses1,2,and5,thetemperaturecoefficient
as specified in Table 1 of any 10-ft (3-m) length shall not vary
10.3 For Alloy Classes 5 to 11 inclusive, the actual resis-
more than 3 ppm/°C from that of any other 10-ft length on the
tance of any 1-ft length of wire in one spool or coil shall not
same spool or coil.
vary by more than 5% from the actual resistance of any other
1 ft of wire in the same spool or coil.
9. Thermal EMF with Respect to Copper
11. Permissible Variations in Dimensions
9.1 The thermal electromotive force (emf) with respect to
copper shall fall within the limits shown in Table 1, in the
11.1 Permissible variations in dimensions of bare wire are
corresponding temperature ranges.
not specified, since these materials are used for resistance
purposes, in which the resistivity and the electrical resistance
10. Permissible Variations in Electrical Resistance
per unit length, rather than the dimensions, are of prime
10.1 The actual resistance per unit length of any wire
importance. The electrical resistance per unit length can be
furnished under these specifications shall not vary from the determined more accurately than the dimensions of very small
nominal resistance by more than the following amounts:
wire.
B267−07 (2013)
A
TABLE 2 Dimensions of Enamel Coated Wire
Nominal Bare Wire Size Light Coated Wire Medium Coated Wire Heavy Coated Wire
Outside Diamete
...
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