I started simply looking at a circuit breaker connection diagram, then I fell down the rabbit hole.(adsbygoogle = window.adsbygoogle || []).push({});

So I wondered, if you had a piece of pure copper and getting rid of heat (structural integrity, gravity etc.) was not an issue, just how much current could you push through it before it hit it's physical limit.

So I went back to basics and looked up resistivity to re-acquaint myself with some units and give me some context:

https://en.wikipedia.org/wiki/Electrical_resistivity_and_conductivity

Annoyingly the maths gives it in terms of physical dimensions and resistance, which I suppose is fair enough, given that it states the cause of it is band-gaps etc. But doesn't really help my thought-experiment.

Then I got onto drift velocity:

u = I n A q u = 1 ( 8.5 × 10 28 ) ( 3.14 × 10 − 6 ) ( − 1.6 × 10 − 19 ) u = − 2.3 × 10 − 5 https://wikimedia.org/api/rest_v1/media/math/render/svg/b86b4325af264ae571d138befb7e1132988de612 https://wikimedia.org/api/rest_v1/media/math/render/svg/b86b4325af264ae571d138befb7e1132988de612

For detail and context see the Numerical Example in:

https://en.wikipedia.org/wiki/Drift_velocity

Then I thought, okay so to begin the thought-experiment I need to think of some physical parameters for my copper, using the resistivity calculate the resistance, then from that divide my supply voltage by that resistance to calculate the current? (And if I'm so inclined also the drift velocity)

However I then considered, what if the supply is pretty much infinitely large; what the electrons just get faster as they approach the speed of light? Resulting in this plasma-like copper conductor as electrons fly through it. That doesn't really sit well with me even in this extremely unrealistic thought experiment, but I concede it being a possibility. I always just expected there was some sort of electron charge density limit to a material to prevent any more electric field or something. But that was just my gut.

Any thoughts?

P.S.I have a second Irritantthat I ran into on the drift velocity page at the bottom, it stated for the above example that the amplitude of an electron of the above drift velocity, in AC was:

[PLAIN]https://wikimedia.org/api/rest_v1/media/math/render/svg/161ff5356c65d6afc22d07317b295fce100c1cf3[PLAIN]https://wikimedia.org/api/rest_v1/media/math/render/svg/161ff5356c65d6afc22d07317b295fce100c1cf3 [Broken]

But I don't understand this numerically (I don't even see how they got that answer) or by derivation (I can't figure out how they got that equation).

I scribbled playing with integration, averages and RMS' of Sine waves but I'm having trouble linking them to speed. Anyone have any clue?

Thanks

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# Maximum current carrying capacity (theoretically infinite?)

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