| General > General Technical Chat |
| why is the US not Metric |
| << < (230/291) > >> |
| KL27x:
--- Quote ---No it's not. Want half the voltage drop? Simply double the cross-sectional area. No need to refer to any charts. Quite the voltage drop is the limiting factor, long before the insulation starts to melt. --- End quote --- Firstly, this is a 1kg per liter of water. How often do you need to do this? Not very. And the easiest way to halve the resistance of your wire is to go take another wire and put two in parallel, lol. Secondly, with AWG, you just go down 3 gauge sizes to double the cross section and halve the resistance. (And you move 6 steps to double/halve the diameter). Every gauge size larger, the diameter of the wire increases by 12.3%. Thus the cross section increases by 1.123^2, or by 26% per step. Going down in size, that is 10.5% decrease in diameter or 20.7% decrease in area. If you know piR^2, you only need to know any one of these numbers. 12.3% is from the 39th root of 92 = 1.122932197. This is because from AWG 36 to 0000, there are 39 steps, and a 0000 wire is 92 times the diameter of a 36 AWG wire. So e.g., If you want double the cross sectional area of an AWG 16 wire, you go to AWG 13. If you do this by cross section, you go from 1.32mm^2 wire to 2.64mm wire. Then you find out that this doesn't exists. And you select the 2.5mm^2 wire. In AWG, you can also be aware of and calculate each step up or down without looking at a chart, only knowing your starting point. You can say it is easier to circumvent AWG and just call it by cross section. But most people probably don't calculate how much cross section they need for a wire, first, then look up the wire, after. Most people probably look a chart or spec sheet to begin with. And naming/buying/selling wires by their cross section isn't necessarily better for your manufacturers and marketplace and engineering codes. You can all it archaic. I call it reality. These are the sizes we (american companies) make wires in and make engineering codes in. You choose from these sizes; you don't design your own spec as you go, unless you crap money like NASA. And in many cases it is easier to use AWG names/standards than to use cross sectional area as a name. If you're gonna use units, you gotta list the units, somewhere, firstly. And when you get smaller than 30 AWG, watch what happens to your names/numbers. AWG is not absolutely empirical. But it is based on the 10.5% reduction in diameter which can be achieved by draw dies on copper alloy. That number is empirical, in a way; it's the average of what can be done, practically, using our current manufacturing techniques and dies and lubricants and alloys. After that, it's a matter of designating a reference/zero/calibration point. Then you know what sizes are actually available by this ratio of 1.122932197 : 1, within a very small margin of error. It would be nice it it were a rounder number, but this is the result of what is the biggest step size in practical application. That's where it ended up, and that's fine. This standard contains, in itself, knowledge of the physical universe and know-how of making wire. Why it goes backwards? Probably because this can be done smaller and smaller, if needed. But going larger is/was determined by other factors (which may have been improved/increased at least 3 times in history? >:D) |
| Mattylad:
The answer to this quandary is actually very simple. They prefer working in feet and inches because there are 12 inches per foot. And we all know that Americans have 6 toes on each foot so they find this one the easiest to count. :) They will catch up with the rest of the world one day. |
| KL27x:
Measuring and communicating distance is not equal to counting. And that is weird that you guys count with your toes. |
| GeorgeOfTheJungle:
Eeny meeny miny moe... |
| tooki:
--- Quote from: KL27x on January 20, 2020, 06:36:19 pm --- --- Quote ---No it's not. Want half the voltage drop? Simply double the cross-sectional area. No need to refer to any charts. Quite the voltage drop is the limiting factor, long before the insulation starts to melt. --- End quote --- Firstly, this is a 1kg per liter of water. How often do you need to do this? Not very. --- End quote --- Actually it’s quite common: when cooking or baking, it’s often best to go by weight of dry ingredients, and so then you can just tare the scale after each ingredient, including liquids. Water is 1kg/l, milk and spirits are close enough. Only oils and sugar syrups require a different ratio. |
| Navigation |
| Message Index |
| Next page |
| Previous page |