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I'm pretty sure that Daniel Young's explanation of surface area
explains the discrepancy.<br>
<br>
The surface area of a larger wire does not grow as fast as its
cross sectional area so<br>
it does not cool as well. It can carry more current but its
surface and temperature<br>
rise is going to be higher if you simply put more amps through it
proportional<br>
to the wire area. <br>
<br>
But the wire table does not show multiple wires in parallel and/or
the distance<br>
between them. Or is there such a table ? If the distance between
them are high<br>
enough so that the heat can be dissipated, then you ~should~ be
able to get<br>
3 times the ampacity of all 3 wires in parallel ? Shouldn't he ?<br>
<br>
What exactly does the title of that column mean ? AWG/KCMIL ?<br>
AWG and KCMIL are different. AWG goes higher as the wire gets
smaller.<br>
KCMIL (area) gets higher as the wire gets bigger.<br>
<br>
boB<br>
<br>
<br>
<br>
<br>
On 12/2/2014 3:32 PM, Larry wrote:<br>
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<div class="moz-cite-prefix">Hey boB,<br>
<br>
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. <br>
<br>
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. <br>
<br>
<img src="cid:part1.03030905.05090603@midnitesolar.com" alt=""><br>
On 12/2/14 3:54 PM, <a moz-do-not-send="true"
class="moz-txt-link-abbreviated"
href="mailto:boB@midnitesolar.com">boB@midnitesolar.com</a>
wrote:<br>
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The "area" of the conductor will be 3 times and you would
think that the NEC Ampacity would also be 3 times<br>
that of one conductor. But one LARGE conductor with the same
area might not be as high as you think<br>
because of insulation. I would think that ampacity of 3
cables in parallel would be 3 times. But probably<br>
not when you take a single cable of the 3X area out of the NEC
table. (I haven't looked at this to verify)<br>
<br>
Also, Larry, 325 AWG 750 AWG (gauge) wire is a bit too small
for this, don't you think ?<br>
<br>
I know... You mean circular mils...<br>
boB<br>
<br>
<br>
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