Is there a Tool for measuring the CSA of wire

[MartinFa]

I'm not too sure why we've gone down the road of evaluating Pi to n decimal places.

If I want to use Pi, I use the Pi key on my calculator and the Pi function in Excel or whatever programming language I happen to be writing in.

IMHO, accuracy beyond the 3rd significant digit is of no value.

 

[MartinFa]

With the prevalence of smartphones and downloadable apps, I've created a simple Excel spreadsheet you can use on a PC or smartphone. As long as you have a vernier caliper for the measuements, just tap in the strand or conductor diameter and the number of strands, and it'll give you the CSA.

You can download it from my website here.

Hope it helps

Since I posted the above, I'd made a change to my website so the original link no longer worked. I've now corrected that, both in my original post, and in the <quote> above.

I also found a free app for Android smartphones that allows you to upload Excel spreadsheets, so you can do the checks on your phone now, too. It's called e-Droid-cell Light. Just search for that on the Google app store (now called "Play" - yuk)

 

[Monkeh]

Seeing as this has been resurrected..

I'm surprised everyone seems to remember pi as 3.14159 rather than the ratio 355/113, which is more accurate.

Not really.
355/113 = 3.1415929203539823008849557522124
But Pi is = 3.1415926535897932384626433832795

So it's only good for one digit more than 3.14159, then it fails badly.

As to the Excel spreadsheet, it's faster to use a calculator.

 

[bernardgreen]

22 / 7 = 3.1428571428571428571428571428571
pi = 3.1415926535897932384626433832795

22 / 7 - pi = 0.00126448926734961868021375957764

which is an error of 0.040249943477068197584079834151885 %

To be that accurate one would need a very expensive vernier gauge.

Aiming Curiousity at Mars may need that degree of accuracy but replacing old Mrs Smith's ancient 7/044 cable doesn't.

And besides the tolerances on the copper strands probably allows more than 1 % difference.

 

[davelx]

try 35500001/11300001

 

[Monkeh]

22 / 7 = 3.1428571428571428571428571428571
pi = 3.1415926535897932384626433832795

22 / 7 - pi = 0.00126448926734961868021375957764

which is an error of 0.040249943477068197584079834151885 %

To be that accurate one would need a very expensive vernier gauge.

Aiming Curiousity at Mars may need that degree of accuracy but replacing old Mrs Smith's ancient 7/044 cable doesn't.

And besides the tolerances on the copper strands probably allows more than 1 % difference.

So again, it's still less accurate. I see no advantage in remembering 22 / 7 over 3.14, which is all 22 / 7 is good for!

 

[JohnW2]

So again, it's still less accurate. I see no advantage in remembering 22 / 7 over 3.14, which is all 22 / 7 is good for!

In the distant pre-calculator days, 22/7 was often useful since it (at least the 22) would often 'cancel' in calculations.

For many real-world applications, just 3, or maybe 3.1, is probably accurate enough - but, certainly in my generation, there were few (even those who did not know what to do with it!) who did not know of pi as 3.1416 or 3.14159.

Kind Regards, John.

 

[ban-all-sheds]

I see no advantage in remembering 22 / 7 over 3.14, which is all 22 / 7 is good for!

22/7 is the same number of characters to remember/keystrokes to enter as 3.14, but it is more accurate.

Accepted though that the accuracy difference is irrelevant in ordinary life.

 

[ban-all-sheds]

Not really.
355/113 = 3.1415929203539823008849557522124
But Pi is = 3.1415926535897932384626433832795

So it's only good for one digit more than 3.14159, then it fails badly.

Fails badly?

355/113 is 7 characters.

3.141592 is 7 characters.

If you round to 6DP the results are the same: 3.141593

To put it in perspective, if you fired a projectile from Land's End to John o' Groats and your lateral aim was out by that many degrees you'd miss your target by less than 5mm.

 

[ban-all-sheds]

http://mathworld.wolfram.com/PiApproximations.html

 

[Monkeh]

Not really.
355/113 = 3.1415929203539823008849557522124
But Pi is = 3.1415926535897932384626433832795

So it's only good for one digit more than 3.14159, then it fails badly.

Fails badly?

355/113 is 7 characters.

3.141592 is 7 characters.

If you round to 6DP the results are the same: 3.141593

To put it in perspective, if you fired a projectile from Land's End to John o' Groats and your lateral aim was out by that many degrees you'd miss your target by less than 5mm.

You do love a good argument, don't you?

And still, 355/113 or 22/7 or any other fractional approximations are no more accurate. They're approximations. I'd rather remember an actual number. 3.1415926 is not exactly difficult.

 

[ban-all-sheds]

It's less efficient for no purpose.

 

[Maxatoria]

I got a plastic drill measuring device that you pop a drill into it and it tells you the size down to 1/10th of a MM for upto 7 MM drills and theres room on the back to glue a laminated table

its probably 20-30 years old from when my dad was in engineering but its something i've not seen around and if i need anything bigger i just get the micrometer out and that will do for stuff upto about 25cm

 

[SimonH2]

Hmm, pie ... feeling hungry again

Said a rather dense schoolboy named Pete
Mathematics has fair got me beat
I'm sure a square root, is some kind of fruit
And Pi is a nice thing to eat

 

[EFLImpudence]

theres room on the back to glue a laminated table

At least you'll hear it when it falls out of your pocket.