Help about wire numbers

[drozer]

Hi to everyone,

I'm new here, so if can someone help me or guide me. I reacentlly use the Softprogram WireGuide99. I wanted to calculate some voltage drop, wire size etc. But now in those calculations I met for wire size (ex. #1;#2 etc.) Can please someone tell me what does this mean?
For ex. #1=1mm2 or I'm wrong?

Sorry for my english, and thanks in advance

 

[Dennis Alwon]

Unfortunately wire sizes are not that simple. For instance a #2 wire is found in the back of the NEC in Table 8. It will give you the cir. mil, area, etc. A #2 is equivalent to a 66360 cir. mil while a #1 is equivalent to 83690 cir. mil.

When you get to sizes like 250 kcm, 300 KCM etc it is simple. 250 kcm is equivalent to 250,000 cir. mil. Can you guess what 300 kcm equals?

 

[GeorgeB]

Hi to everyone,

I'm new here, so if can someone help me or guide me. I recently use the Softprogram WireGuide99. I wanted to calculate some voltage drop, wire size etc. But now in those calculations I met for wire size (ex. #1;#2 etc.) Can please someone tell me what does this mean?
For ex. #1=1mm2 or I'm wrong?

Sorry for my english, and thanks in advance

Many years back, I determined an equation to relate AWG (American Wire Gauge) to diameter in inches. While not metric, I'm sure you can convert inches to mm. That equation, expressed for Excel, is

Diameter =EXP((36-A2)/39*LN(92))/200 with awg in A2

I also did the reverse, not as trivial as simple algebra, to get AWG from area in square mm. If you are european, this may be more useful

AWG=17-4.27*LN(A4) with square mm in A4

 

[drozer]

Hi everyone, and thanks for your replay,

Yes I'm European (or I sure hope so:grin
I saw your equation but I didn't understood. What is A2, A4, which table is that NEC 8, cir.mil. ?
Can you give me something to see?

Thanks

 

[winnie]

'American Wire Gauge' or AWG is an exponential series where each wire size is the same percent larger than the previous wire size. In other words, an 8ga wire X% larger than a 10ga wire, by the same factor than a 10ga wire is larger than a 12ga wire.

See definition 3 for gauge http://www.unc.edu/~rowlett/units/dictG.html#gauge The equation given at the end of the paragraph corresponds to the equation given by GeorgeB; George does it with natural log and exponents; the official defining equation does it with the number 92 raised to a fractional power, and by inspection the two equations give equivalent results.

NEC is the National Electrical Code published by the NFPA. Table 8 is toward the back of the book, and is a table of wire properties, including cross sectional area in both circular mil and mm^2.

Getting from AWG to mm^2 is a matter of using the equation to determine the diameter of the wire in inches, converting that value to a diameter in mm, and then using the equation relating the diameter of a circle to it's area to get the cross section in mm^2.

George, the reverse equation that I get (from mm^2 to AWG) is 17.160 - 4.312*ln(A) = N where A is the area in mm^2 and N is the AWG. I presume that the small differences are rounding.

-Jon

 

[Dennis Alwon]

Can you give me something to see?

Thanks

Let's see how this comes out. From the NEC National Electric Code

 

[jghrist]

If you are doing work in Europe, you should get a program that handles metric wire sizes. If the program you're using deals in AWG and MCM (or kcmil), then it also probably sizes wire according to American codes instead of IEC or European national codes.

 

[GeorgeB]

Hi everyone, and thanks for your replay,

Yes I'm European (or I sure hope so:grin
I saw your equation but I didn't understood. What is A2, A4, which table is that NEC 8, cir.mil. ?
Can you give me something to see?

Thanks

A2 and A4 are Excel cells, nothing more. The relationships are not taken from the NEC, rather from wire tables I had at the time.

 

[GeorgeB]

George does it with natural log and exponents;

If you wonder why, I did this in early CP/M days using Suprcalc (which didn't directly have base10 logs). I think that Excel still has that limitation in some versions.

the official defining equation does it with the number 92 raised to a fractional power, and by inspection the two equations give equivalent results.

thanks for the link to the definition; I did this with a curve fit program.

George, the reverse equation that I get (from mm^2 to AWG) is 17.160 - 4.312*ln(A) = N where A is the area in mm^2 and N is the AWG. I presume that the small differences are rounding.

-Jon

The small differences are more likely in my intelligence ... or lack thereof. In reality, I took what I could find and fed it into the curvefit program I had and liked, but which was in pre-PC BASIC and never worked in GWBASIC. That program had been adapted by a friend from one written for an HP45 programmable calculator ... I'm OLD.

 

[winnie]

Figuring out the equation from the tabulated (and rounded) numbers is no trivial feat! That is where the differences come from: you had rounding to deal with; I was doing algebra from the definition.

-Jon

P.S. I've done a bit of basic in my time Also 6502 assembly.

 

[drozer]

hi

hi

Hi
Thanks for replies to everyone,

Jghrist, yes I'm working in Europe, so can you tell me some programs that I can download from internet (offcourse for FREE)? I busted my ass with this American sizes (no hard feelings Americansgrin.

George, you are not OLD, never say that! You have more experience than us

Denis, thaks very much for the table, although I can't see almost nothing.

Thx again to everyone