Copper bar (copper bus) resistivity, conductivity, conductivity

Copper bar (copper bus) resistivity, conductivity, conductivity

Industry standard: YS/T 478-2005 Copper and copper alloy conductivity eddy current testing method


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Resistivity (resistivity):

It is a physical quantity used to express the resistance characteristics of various substances. At room temperature (at 20°C), the resistance of a wire made of a material with a length of 1 meter and a cross-sectional area of 1 square millimeter is called the resistivity of this material.


Under a certain temperature, there is the formula R=ρl/s where ρ is the resistivity, l is the length of the material, and s is the area. It can be seen that the resistance of the material is proportional to the length of the material and inversely proportional to its area. From the above formula we can see the definition of resistivity: ρ=Rs/l

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Resistivity calculation formula:

The calculation formula of resistivity is: ρ=RS/L

Ρ is the resistivity-commonly used unit Ω.mm2/m

S is the cross-sectional area-commonly used units mm2

R is the resistance value-commonly used unit Ω

L is the length of the wire-commonly used unit m


Sample conductivity:

The percentage of the ratio to a certain standard value is called the conductivity of the sample.

In 1913, the international annealed copper standard stipulated that an annealed copper wire with a density of 8.89g/cm3, a length of 1m, a mass of 1g, and a resistance of 0.15328 ohms was used as the measurement standard. At a temperature of 200C, when the electrical resistivity of the annealed copper wire is 0.017241Ω.mm2/m or the electrical conductivity is 58.0 MS/m), it is determined to be 100% IACS (International Annealed Copper Standard), and the conductivity of any other material ( %IACS) can be calculated using the following formula:


Conductivity (%IACS)=0.017241/ ρ*100%


1. The reciprocal of the resistivity is the conductivity. σ=1/ρ

2. Unit: In the International System of Units, the unit of conductivity is Siemens/m (MS/m).

3. The physical meaning of electrical conductivity is to indicate the electrical conductivity of a substance.

The greater the electrical conductivity, the stronger the electrical conductivity, and vice versa.

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20℃DC resistivity





0.017 241




0.017 77




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