Conductor Materials

Metal Properties

Specific Gravity and Density: Specific gravity is the ratio of mass of any material to that of the same volume of water at 4 °C. Density is the unit mass of material to that of volume at some reference temperature, usually 20 °C. The numerical values, for all practical purposes, when density is expressed in g/cu.cm is same.

Density and Weight of Copper: Pure copper, rolled, forged or drawn and then annealed, has a density of 8.89 g/cm³ at 20 °C or 8.90 g/cm³ at 0 °C. Samples of high conductivity copper usually will vary from 8.87 to 8.91 and occassionally from 8.83 to 8.94. Variation in density may be caused by microscopic flaws or seams or the presence of scale or some other defect; the presence of 0.03 % oxygen will cause a reduction of about 0.01 in density. Hard drawn copper has about 0.02 % less density than annealed copper, on average, but for practical purposes, the difference is negiligible.

The international standard of density, 8.89 at 20 °C, corresponds to a weight of 0.32117 lb/in³.

Copper Alloys: Density and mass of copper alloy varies with the composition. For hard-drawn wire covered by ASTM specification B105, the density of alloy 85 to 20 is 8.89 g/cm³ at 20 °C; alloy 15 is 8.54; alloy 13 and 8.5 are 8.78.

Copper Clad Steel: Density and weight of copper-clad steel wire is a mean between the density of copper and the steel, which can be calculated readily when the relative volumes or cross section of copper and steel are known. For practical purposes, a value of 8.15 g/cm³ at 20 °C is used.

Aluminium Wire: Density and weight of aluminum wire (commercially hard-drawn) is 2.705 g/cm³ at 20 °C. With less pure material there is an appreciable decrease in density on cold working. Annealed metal having a density of 2.702 will have a density of 2.700 when in hard-drawn or fully cold-worked conditions.

Aluminum-Clad Wire: Density and weight of aluminum clad wire is a mean between the density of aluminum and the density of steel, which can be calculatec readily when the relative volumes or cross sections of aluminum and steel are known. For practical purposes, a value of 6.59 g/cm³ at 20 °C is used.

Aluminum Alloys: Density and weight of aluminum alloy varies with type and compositions. For hard drawn aluminum alloy wire 5005-H19 and 620-T81, a value of 2.703 g/cm³ at 20 °C is used.

Pure Iron and Galvanised Steel Wire: Density and weight of pure iron are 7.90 g/cm³ at 20 °C. Density and weight of galvanised steel wire (EBB, BB, HTL-85, HTL-135 and HTL-195) with class A weight of zinc coating are 7.83 g/cm³ at 20 °C, with Class B are 7.80 g/cm³, and with Class C are 7.78 g/cm³.

Percent Conductivity: It is very common to rate the conductivity of a conductor in terms of its percentage ration to the conductivity of chemically pure metal of the same kind as the conductor is primarily constituted or in ratio to the conductivity of the international copper standard. Both forms of the conductivity are useful for various purposes. The ratio can also be expressed in two different terms, one where the conductor cross sections are equal and therefore termed the volume conductivity ratio and the other where the conductor masses are equal and therefore termed the mass-conductivity ratio.

International Annealed Copper Standard: The IACS is the internationally acceptted value for the resistivity of annealled copper of 100 % conductivity. The standard is expressed in terms of mass resistivity as 0.15328 Ω.g/m², or the resistance of a uniform round wire 1m long weighing 1g at 20 °C. Equivalent expressions of the IACS in various units are: 857.20 Ω.lb/mi²; 1.7241 µΩ⋅cm; 0.67879 µΩ⋅in; 10.371 Ω.cmil/ft; 0.017241 Ω.mm²/m.

The preceding values are the equivalent of 1/58 Ω.mm²/m, so the volume conductivity can be expressed as 58 S.mm²/m at 20 °C.

Electrical Resistivity: Electrical resistivity is a measure of the resistance of a unit quantity of a given material. It may be expressed in terms of either mass or volume; mathematically, mass resistivity: δ = Rm/l²; volume resistivity: ρ = RA/l; where R is resistance, m is mass, A is cross-sectional area, and l is length.

Electrical Conductivity and Resistivity - Non-ferrous Conductors
SpecificationTemper and shapeSize limitsConductivity at 20 °CWeight ResistivityVolume Resistivity
  inIACS, %Ω⋅g/m²Ω⋅mm²/m
Copper and copper alloy – specific gravity 8.89:
 .......................100.170.153020.017213
B4Low resistance Lake wirebarAll100.000.153280.0107241
B5Electrolytic wirebar
B170Oxygen-free wirebar
B187Soft bus-bar, rod and shape
B188Soft bus tube
B298Silver coated soft, round
B75Tube, soft, OF copper
B49Hot-rolled rod1.375 - 0.250100.000.153280.017241
B3Soft, roundAll
B48Soft, rectangularAll
 .......................99.50.154050.017328
 .......................99.000.154820.017416
 .......................98.500.155610.017504
B187Hard bus bar, rod and shapeOver 1 in OD98.40.155770.017521
Over 0.375 × 4
B188Hard bus bar, rectangular or squareOver 6 in
B75Tube, soft, DLP copperAll98.160.15614 
B188.......................98.000.156400.017593
Hard bus tube, rectangular or squareUp to 6 × 3/16 in wall97.800.156730.017629
B2Medium hard, round0.460 - 0.32597.660.156940.017654
B33Tinned soft, round0.460-0.290
B189Lead-coated soft, round0.460-0.290
 .......................97.500.157210.017683
B187Hard bus bar and rodUpto 1 in OD97.400.157370.017701
Upto 0.375 × 4
B188Hard bus tube, roundOver 1 in OD
Hard bus pipe, IPS and extra strongOver 4 in OD
Hard bus tube, rectangular or squareUpto 6 in, over 3/16 in wall
B75Tube, hard, OF copperAll
B372Waveguide tube, OF copper 
 .......................97.300.157530.017720
B1Hard, round0.460-0.325   
B47 and B116Hard trolley wireAll97.160.157750.017745
B33Tinned soft, round0.289 - 0.103
B189Lead-coated soft, round 
 .......................97.000.158020.017775
B2Medium hard, round0.324-0.040396.660.158570.017837
B188Hard bus pipe, SPS and extra strongUpto 4 in OD96.600.158650.017845
 .......................96.500.158840.017867
B1Hard, round0.324 - 0.040396.160.159400.017930
B33Tinned soft, round0.102-0.0201
B189Lead coated soft, round0.102 - 0.0201
B75Tube, hard, DLP copperAll96.160.159400.017930
B372Waveguide tube, DLP copper
B355Nickel-coated soft, round, Class 2All96.000.159660.017960
B33Tinned soft, round0.0200 - 0.011194.160.162790.018312
B189Lead-coated soft, round
B355Nickel-coated soft, round, Class 4All94.00.163060.018342
B246Tinned medium hard, round0.2043-0.10393.220.164430.018495
B33Tinned soft, round0.0110 - 0.003093.150.164540.018508
B189Lead coated soft, round
B246Tinned hard, round0.2043-0.10392.720.165320.018595
B246Tinned medium hard, round0.103-0.050892.510.165690.018637
B246Tinned hard, round0.103-0.050891.960.166680.018748
B355Nickel-coated soft, round, Class 7All91.000.168440.018947
 .......................90.000.170310.019157
B355Nickel-coated soft, round, Class 10All88.00.174180.019592
B105Hard round, alloy 85All850.180390.020291
B105Hard round, alloy 80All800.191600.021551
B9Trolley wire, alloy 80
B355Nickel-coated soft, round, Class 27All71.00.215880.024284
B105Hard round, alloy 65All650.235730.26516
B9Trolley wire, alloy 65
B105Hard round, alloy 55All550.278640.031343
B9Trolley wire, alloy 55
B105Hard round, alloy 40All400.383200.043103
B9Trolley wire, alloy 40
B105Hard round, alloy 30All300.510860.057465
B105Hard round, alloy 20All200.766380.086207
Resistivity temperature constant..........0.0005970.0000681
Copper alloy – specific gravity 8.54:
B105Hard, round, alloy 15All150.981620.11494
Resistivity temperature constant..........0.0005970.0000681
Copper alloy – specific gravity 8.78:
B105Hard, round, alloy 13All131.16450.13263
B105Hard, round, alloy 8.5All8.51.78090.20284
Resistivity temperature constant..........0.0005970.0000681
Aluminum and aluminum alloy – specific gravity 2.703:
B233Redraw rod 1350-01.00061.80.0754100.027899
Redraw rod 1350-H12 and -H2261.50.0757780.028035
Redraw rod 1350-H14 and EC-H2461.40.0759010.028080
Redraw rod 1350-H16 and EC-H2661.30.0760250.028126
B236Bus barAll610.076400.028264
B230Hard, roundAll61.00.0763990.028265
B262Three-quarter hard, round
B323Half hard, round
B314Half hard, round
B324All tempers, rectangularAll61.00.0763970.028264
B317T64 temper, extruded alloy 6101All59.50.07820.028976
B317HI11 temper, extruded alloy 6101All59.00.07890.029222
B317T61 temper, extruded alloy 6101All57.00.08170.030247
B317T65 temper, extruded alloy 6101 56.50.0824010.030518
B317T63 temper, extruded alloy 6101All56.00.08310.030788
B317T6 temper, extruded alloy 6101All55.00.08460.031347
B396Hard round, alloy 5005All53.50.0871060.032226
B398Hard round, alloy 6201All52.50.0887640.032839
Resistivity temperature constant..........0.0003050.000115
Copper-clad steel – specific gravity 8.15:
B227Hard, round, grades 40 HS and EHSAll400.0358370.043971
B227Hard, round, grades 30 HS and EHSAll300.0477730.058617
Resistivity temperature constant (40 %)..........0.001350.000167
Resistivity temperature constant (30 %)..........0.001790.000222
Aluminum-clad steel – specific gravity 6.59:
B415Hard, round0.204-0.080200.558860.084805
Resistivity temperature constant..........0.002000.000306
Electrical Conductivity and Resistivity - Ferrous Conductors
MaterialASTM specificationWeight resistivity at 20 °CVolume resistivity at 20 °C
MaximumAverageRangeAverage
Ω⋅lb/mi²µΩ⋅cm
Pure Iron........4410............9.78
Contact Rails:     
   Openhearth....................16.6 - 22.4 
   Mild to soft steel....................12.8 - 15.8 
Telephone and telegraph (galvanized):     
   Extra Best Best (EBB)A1115000   
   Best Best (BB)A1115600   
   Grade 85A3265800   
   Grade 135 and 195A3266500   
Commercial galvanized:     
   Siemens-Martin..............7280......16.3*
   High strength..............9000......20.1*
   Extra-high strength..............9360......20.9*

Note: *Calculated from average resistivity, with average specific gravity 7.83

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