How to Calculate the Wire Gauge Per Temperature Rise
- 1). Look up the relevant linear expansion coefficient, α, for the substance of interest. For example, if you're working with copper wire, α is 17 x 10^-6 per degree Celsius.
- 2). Measure the change in gauge, meaning the diameter of the wire, from using the linear expansion coefficient. For example, for a copper wire, the diameter would increase by a factor of 1 + 17 x 10^-6, which is its linear expansion coefficient, α.
- 3). Translate the linear expansion into area expansion. This will allow you to find the change in gauge, where "gauge" means wire cross-section. Linear expansion applies to both length and width. Since cross section is a product of length and width, the cross sectional area would increase by a factor of (1+α)^2 - 1. For example, for a copper wire, the cross section would increase by a factor of (1 + 17 x 10^-6 )^2 - 1, or 34 x 10^-6 per degree Celsius.
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