<html>
<body>
I think this answers a question I was pondering. If a conduit is
run on standoffs over a roof, the temperature is cooler than on the roof,
so the derating of the wire's ampacity is less. It would appear
from 310.15(A)(2) Exception that it would <u>not</u> be necessary to
limit the ampacity of the wire to that of the hottest temperature zone,
which is zero distance above the roof where the conductors
penetrate. <br><br>
Is this a correct interpretation?<br><br>
Thanks,<br><br>
Drake <br><br>
At 01:51 PM 8/17/2011, you wrote:<br>
<blockquote type=cite class=cite cite="">As I read the rule, that 100' in
the trench allows you to go 10' above grade on each side while just
worrying about the ampacity in the 100' section (be sure to check that
your terminals are OK). For 200' in the trench, you're still looking at
10' above grade on each side. The rule doesn't say that you can only use
this exception once per circuit, so it's fine that you use it once at
each end.<br><br>
<br>
On 2011/8/17 12:22, Brian Mehalic wrote:<br>
<blockquote type=cite class=cite cite="">Question about the 10'/10% rule
- the exception states "adjacent<br>
portions of a circuit." How does this apply to an underground
conduit<br>
run, where there are two ends exposed to higher ambient temperatures<br>
than the length in the ground?<br><br>
For example, what if there is 100 feet in the trench, and 7 feet
above<br>
grade on either side? Can the exception be applied? How about 200
feet<br>
in the trench and 7 feet above grade on either end?<br><br>
Thanks,<br>
Brian<br><br>
--<br>
========================<br>
Brian Mehalic<br>
NABCEP Certified Solar PV Installer™ R031508-59<br>
IREC ISPQ Certified Affiliated Instructor/PV US-0132<br>
PV Curriculum Developer and Instructor<br>
Solar Energy International<br>
Carbondale, CO 81623<br>
<a href="http://www.solarenergy.org/" eudora="autourl">
http://www.solarenergy.org</a><br><br>
<br><br>
_______________________________________________<br>
List sponsored by Home Power magazine<br><br>
List Address: RE-wrenches@lists.re-wrenches.org<br><br>
Options& settings:<br>
<a href="http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org" eudora="autourl">
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org</a>
<br><br>
List-Archive:
<a href="http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org" eudora="autourl">
http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org</a><br>
<br>
List rules& etiquette:<br>
<a href="http://www.re-wrenches.org/etiquette.htm" eudora="autourl">
www.re-wrenches.org/etiquette.htm</a><br><br>
Check out participant bios:<br>
<a href="http://www.members.re-wrenches.org/" eudora="autourl">
www.members.re-wrenches.org</a><br>
</blockquote>_______________________________________________<br>
List sponsored by Home Power magazine<br><br>
List Address: RE-wrenches@lists.re-wrenches.org<br><br>
Options & settings:<br>
<a href="http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org" eudora="autourl">
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org</a>
<br><br>
List-Archive:
<a href="http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org" eudora="autourl">
http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org</a><br>
<br>
List rules & etiquette:<br>
<a href="http://www.re-wrenches.org/etiquette.htm" eudora="autourl">
www.re-wrenches.org/etiquette.htm</a><br><br>
Check out participant bios:<br>
<a href="http://www.members.re-wrenches.org/" eudora="autourl">
www.members.re-wrenches.org</a><br>
</blockquote>
<x-sigsep><p></x-sigsep>
<font size=2>Drake
Chamberlin<x-tab> </x-tab>
<br>
ATHENS ELECTRIC<br>
OH License
44810<x-tab> </x-tab><br>
CO license 3773<br>
NABCEP Certified PV<br>
</font></body>
</html>