[e2e8]

awg14 or whatever isn't exactly the perfect gauge for whatever application it is used for. It is somewhat arbitrary. A nice metric system of gauges would have 2 mm, 2.5 mm, 3 mm, etc. and there would be still be a nice round number gauge for each application.

[Turing_Machine]

For some value of "nice round number". What really matters with most wires is the current carrying capacity, which largely depends on the cross-sectional area, not the diameter. Equally-spaced diameters don't give you equally-spaced areas.

[jacobolus]

If you have an industrial production process which is going to produce a set number of wire sizes, and you want them to be maximally useful for a wide variety of applications, you want a logarithmic scale.

Responding to commenter e2e8: Using 2mm, 3mm, etc. would be substantially less functional.

Once you have a log scale, it hardly matters whether you measure diameter or area, that’s just a constant factor.

In the ideal case, the log scale would have a slightly easier to compute definition for the dilation at each step than the 39th root of 92 (~1.1229).

Perhaps they could use the 6th root of 2 instead (~1.1224). Then every 6 steps you’d get a factor of two. Size 0 could be defined as 1mm diameter (or size 0 could be 1 millimeter squared cross sectional area, with 3rd root of 2 as the step each time).

In practice if you’re wiring a house, it doesn’t much matter.

* * *

One of the reasons the metric system built on a base ten number system is so frustrating for practical purposes is that powers of ten are entirely arbitrary and indivisible, and tenth roots of ten or numbers expressed in terms of natural logarithms are even worse. We’d be much better off with a general-purpose base twelve number system, plus log scales uniformly designed around the twelfth root of 2. [Western music scale, ISO paper sizes, etc. would fit right in.]

[fanf2]

AWG is exponential not logarithmic.

For an exponential scale you can just pick some reasonably evenly-spaced round numbers and repeat them at different factors of 10: 1, 2, 5, 10, 20, 50, ...

[e2e8]

You can plot out the wire gauges you want on a log scale and then round them to nice whole (metric measurement) numbers. That is in fact what is done for things like fasteners.

[jacobolus]

And then when you try to scale your whole design up, whoops, all the rounding changes and you need to redo everything.

Anyway, neither way here is right or wrong. One optimizes for uniformity of scaling, the other optimizes for intelligibility with a base ten number system.

[arielb1]

It's not like you are making tight fits with wires anyway, a millimeter here or there won't matter.

However, using something like the E12 series would work pretty well.

[e2e8]

Sure. Those number I gave could be areas. I am not certain this the right standard, but IEC 60228 specifies 0.5 mm2, 0.75 mm2, 1 mm2, 1.5 mm2, 2.5 mm2, 4 mm2 etc...

https://en.wikipedia.org/wiki/IEC_60228