nanog mailing list archives
Re: L6-20P -> L6-30R
From: Rob Seastrom <rs () seastrom com>
Date: Wed, 19 Mar 2014 18:33:18 -0400
Jay Ashworth <jra () baylink com> writes:
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.
It's not the conductor that you're derating; it's the breaker. Per NEC Table 310.16, ampacity of #12 copper THHN/THWN2 (which is almost certainly what you're pulling) with 3 conductors in a conduit is 30 amps. Refer to Table 310.15(B)(2)(a) for derating of more than 3 current-carrying conductors in a conduit. 4-6 is 80%, 7-9 is 70%. Plenty good for 20 amps for any conceivable number of conductors in a datacenter whip. Thermal breakers are typically deployed in an 80% application for continuous loads, per NEC 384-16(c). See the references to 125% of continuous load, which of course is the reciprocal of 80%. http://cliffordpower.com/wp/wp-content/uploads/2010/08/CPS_info_sheet_37_CB_80_versus_100.pdf -r
Current thread:
- Re: L6-20P -> L6-30R, (continued)
- Re: L6-20P -> L6-30R Chuck Anderson (Mar 19)
- Re: L6-20P -> L6-30R Justin M. Streiner (Mar 18)
- Re: L6-20P -> L6-30R Jay Ashworth (Mar 18)
- Re: L6-20P -> L6-30R Randy (Mar 18)
- Re: L6-20P -> L6-30R Jeremy Bresley (Mar 18)
- RE: L6-20P -> L6-30R Staudinger, Malcolm (Mar 19)
- Re: L6-20P -> L6-30R Joel Maslak (Mar 19)
- Re: L6-20P -> L6-30R Jay Ashworth (Mar 19)
- Re: L6-20P -> L6-30R Seth Mattinen (Mar 19)
- Re: L6-20P -> L6-30R Jay Ashworth (Mar 19)
- Re: L6-20P -> L6-30R Rob Seastrom (Mar 19)
- Re: L6-20P -> L6-30R Lamar Owen (Mar 20)
- Re: L6-20P -> L6-30R Rob Seastrom (Mar 20)
- Re: L6-20P -> L6-30R Gary Buhrmaster (Mar 20)
- Re: L6-20P -> L6-30R Lamar Owen (Mar 20)
- Re: L6-20P -> L6-30R Gary Buhrmaster (Mar 20)
- Re: L6-20P -> L6-30R Brandon Galbraith (Mar 20)