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| why is the US not Metric |
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| KL27x:
--- Quote ---Instead of 40 gauges and 4 different 0 gauges, you could have 0.01mm .. 1mm in 0.01 steps or 0.025mm steps , 1mm..2mm in 0.1 steps, 2mm+ in 0.25mm steps ... not that hard. --- End quote --- But the size of the wire in diameter doesn't not change in a fixed step size. It changes as the square root of a fixed percentage. So if you measure by diameter, the step size will get larger as the wire gets larger, and it will get smaller as the wire gets smaller. The discrete sizes we have are determined by the physical properties of wire. The jumps between draw dies are based on how much the wire can be drawn at one time without adverse consequences, like the wire breaking or being less uniform. This ends up something to do with square root 39 or 92 or some weird number. This is to get the maximum useful sizes of wire in the least number of steps/cost from the starting extruded stock materials/slugs. --- Quote ---How is it easier to say 14 gauge... do you keep in your head all the diameters and areas for all gauges? --- End quote --- First off, I do say and think in gauge. I don't keep all the diameters in my head, but I know some key numbers which I commonly use. Without looking it up, I know 30AWG is about 8.5 thous to just shy of 10 thous in diameter, depending on where you buy it. And I know 16 AWG power cord is very typical for most hand held power tools, which is rated for probably ~10 amps, continuous. I know 22 AWG will be around what most people like to stick in a breadboard. I know modern small components thru hole leads are thinner than that, though. Maybe as little 24-26 AWG. If you go by diameter, you still have to look things up. When you do your calculation and figure out you need 0.38185 mm2 wire, you can't just order that. You have to look up the closest sizes. Gauge is a standard, not a unit. Once you figure out the gauge, then you can buy it by the standard. Also, when you calculate everything by square mm, but you call it by diameter, do you not end up having to say diameter? That is already way stupider to say than gauge. Another thing you can say is that pipe sizes in imperial are dumb. But a "schedule 40" pipe is not just a size. It's a standard which specifies tolerance in composition and a specific manufacturing technique, all of which result in a specific product, which welds a specific way, and will withstand specific pressures and lateral and environmental stresses when fitted and welded to the further standards employed by pipeline construction. It's more than just an arbitrary ID and OD. And if you make it 20% bigger in all dimensions (or physically change the dimensions to match better with metric), your workforce will have to relearn/recertify in the protocols for welding it, and we won't know all the repercussions for another 50 years down the line. AWG is not as complex of a standard, but it is a standard. Drawing a wire changes the structure and physical properties. An extruded or turned wire will not be the same as a wire drawn to the same size. The two wires will not be the same thing. AWG conveys more than just the diameter of the wire, although you could just assume that going by diameter does the same, of course. You just won't get the neat quantum steps you envision, unless you use some new non-linear unit based on the formula used for drawing wire? (And then you would end up with something very similar to gauge; albeit, potentially inverted). ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; --- Quote ---No. It must be something that appeals to what they are crazy for, something they won't resist or raise objections to. --- End quote --- With a demographic as diverse as the US, maybe this can best be summed by cost. If it reduces our taxes, then we would probably do it. Since the opposite will happen, and the only "inconvenience" to not mandating a change is that we continue to use a system we actually like, in addition to metric, then good luck finding this silver bullet. Using both systems is not a detriment. Using a uniquely different systems in each state would be a detriment. That is why the change to metric was more important in Europe. |
| stefan_trekkie:
We don't use diameters for wires. We use the aria of the wire .. 0.5mm² .. 6mm² ... etc .. And the calc is easy and done for a second - there are tables for that and the super fast .. 1mm² - 6 amps current limit (may be more on some specialized cables but in general) .. So if you have 3kw consumer for example .. 240 volts (or 400v 3 phase even at home) That are 12 amps .. That is 2mm² or more .. (0.5, 0.75, 1, 1.5, 2.5, 4, 6, 10 are the standards) Also for short we don't use mm² .. We just say (how many) squares |
| KL27x:
And... those are no longer units. They're standards. Rounded off to certain whole nominal numbers. So now, to make close calculations like what bsfeechannel wants to do, you have to look up the actual areas of the wire. And you also don't know from looking at one catalog, if there are other sizes available between say 4 and 6 or 6 and 10. Unless you look at a chart of the standards. This is a small improvement in utility and doesn't help too much. At least when I say 12 AWG, I know it's a thing. I don't have to look it up to make sure if it exists or not, like saying 8mm^2 wire. Does this exist (under $10,000 for a custom run)? Is it between steps? If I am using I suppose you will have to refer to your chart. Even in AWG, certain sizes might not be cheap or common, I suppose. Sometimes it's cheaper to skip some gauges, for manufacturing/market reasons. So it's not all that big a problem. But it's a thing. Your 10mm wire might round to 11, irl, but called 10mm, because it sounds better, and the next size up is much bigger than 11, anyway. |
| stefan_trekkie:
Nope. There are no standards between that.. Everything is on that chart .. If you need 8mm² by calculation (as was your example) you just now that is no such thing and use next big one - 10mm² .. next is 16, 25, 35 etc... (very big industrial cables) Big ones increase in smaller steps and i don't have used ones above 10mm² that are not 3 phase .. But should exist. EDIT: the specialized wires for bobbins and transformers have tiny steps |
| KL27x:
Isn't that basically what I just said? That you have to refer to a chart, anyway, to source and buy and to look up actual dimensions if doing a close calculation. If I'm a seller of this wire, can I just put the calipers on it and calculate cross sectional area and list what I measure? No. I might measure the 10mm^2 as 11. And no one will find my listing. You have to look up the standards. The way you make the standard sound like a measurement can be detrimental, in some ways, when it comes to communication. I'm also curious to see how this system works out at the finer end, say 36-40 AWG. Remember that jumping between mm^2 and micrometers^2 is 6 significant digits, so you are stuck with some zeros or some really large numbers in micrometers. In truth, you will learn what steps are there, in w/e work you are doing. You're just learning stupider numbers, like you might know 1.5 and 2.5 is wire sizes. But 2, 3, 4 are not (dunno for sure), because you work with those wire sizes. The AWG system separates the standard from the units, and it can be described in any unit of measurement. This seems like a good idea for this particular thing. Esp when the actual dimensions of the wire are needed. You will be calling it by the standard size and also using the real size, both in "mm^2." |
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