[169892] in North American Network Operators' Group
Re: L6-20P -> L6-30R
daemon@ATHENA.MIT.EDU (Seth Mattinen)
Wed Mar 19 17:52:25 2014
Date: Wed, 19 Mar 2014 14:51:54 -0700
From: Seth Mattinen <sethm@rollernet.us>
To: nanog@nanog.org
In-Reply-To: <21771767.12127.1395249665075.JavaMail.root@benjamin.baylink.com>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On 3/19/14, 10:21, Jay Ashworth wrote:
> It is exactly that: no one says you*can't* wire a 20A branch circuit with
> #10.
>
> It is even*possible*, though unlikely, that if you did so, you wouldn't
> have to derate it to 80%. I would have to reread the Code to be sure.
Well, I'd say it's pretty likely. However highly unlikely to be
code-worthy of slapping on a 30A breaker in place of a 20. 10-20 CCCs in
a raceway or cable is a 50% derating, so if those conductors were for
20A branch circuits it would have to be 10AWG, not 12 since with 10AWG
you're derating from 40A. But the max protective device on 10AWG is 30A
unless permitted by 240.4.
Even 7-9 CCCs in a raceway or cable derates 10AWG to 28A (70%), so while
still suitable for a 20A breaker it's not for 30A. Max would be 6 CCCs
to stay at 80% derating (4-6 CCCs).
~Seth
