[RE-wrenches] Parallel Wire combining

[Jerry Shafer]

To All from wikipedia
Increasing gauge numbers denote decreasing wire diameters, which is similar
to many other non-metric <http://en.wikipedia.org/wiki/SI> gauging systems.
This gauge system originated in the number of drawing operations
<http://en.wikipedia.org/wiki/Wire_drawing> used to produce a given gauge
of wire. Very fine wire (for example, 30 gauge) required more passes
through the drawing dies <http://en.wikipedia.org/wiki/Draw_plate> than did
0 gauge wire. Manufacturers of wire formerly had proprietary wire gauge
systems; the development of standardized wire gauges rationalized selection
of wire for a particular purpose.* In short gauge is only a number nothing
else*

On Tue, Dec 2, 2014 at 2:20 PM, boB at midnitesolar.com <boB at midnitesolar.com>
wrote:

>
> The only thing I can think that AWG/KCMIL means is that it is a ratio ?
>
> boB
>
>
>
> On 12/2/2014 4:18 PM, boB at midnitesolar.com wrote:
>
>
> I'm pretty sure that  Daniel Young's explanation of surface area explains
> the discrepancy.
>
> The surface area of a larger wire does not grow as fast as its cross
> sectional area so
> it does not cool as well.  It can carry more current but its surface and
> temperature
> rise is going to be higher if you simply put more amps through it
> proportional
> to the wire area.
>
> But the wire table does not show multiple wires in parallel and/or the
> distance
> between them.  Or is there such a table ?  If the distance between them
> are high
> enough so that the heat can be dissipated, then you ~should~ be able to get
> 3 times the ampacity of all 3 wires in parallel ?  Shouldn't he ?
>
> What exactly does the title of that column mean ?  AWG/KCMIL ?
> AWG and KCMIL are different.  AWG goes higher as the wire gets smaller.
> KCMIL (area) gets higher as the wire gets bigger.
>
> boB
>
>
>
>
> On 12/2/2014 3:32 PM, Larry wrote:
>
> Hey boB,
>
> This is the reference table I was using. They show 325 AWG and 325kCM
> refer to the same diameter cable but I should have used kcm for clarity.
>
> If all insulation/temp rating is the same we are back to my original
> question. Anyone else able to explain this? To be safe I am leaning toward
> using the combined CM number to size for current rather than 3 times the
> ampacity as that just makes no sense to me.
>
>
> On 12/2/14 3:54 PM, boB at midnitesolar.com wrote:
>
>
> The "area" of the conductor will be 3 times and you would think that the
> NEC Ampacity would also be 3 times
> that of one conductor.   But one LARGE conductor with the same area might
> not be as high as you think
> because of insulation.  I would think that ampacity of 3 cables in
> parallel would be 3 times.  But probably
> not when you take a single cable of the 3X area out of the NEC table.  (I
> haven't looked at this to verify)
>
> Also,  Larry,  325 AWG 750 AWG (gauge) wire is a bit too small for this,
> don't you think ?
>
> I know...  You mean circular mils...
> boB
>
>
>
>
>
>
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