Also look at the notes to the tables in Chapter 9. For conduit fill,
all wires are counted. 310.15 covers ampacity derating for more than 3
current carrying conductors in the raceway. The key is "current carrying
conductors". The neutral definitely carries current. You don't have to
count grounding conductors, control, or signal wiring for that ampacity
derating, because they don't create heat. But they still count for
conduit fill, though.
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 4/21/2016 11:35 AM, Patrick A. Shortell wrote:
You should find your answers in 310.15
Patrick A. Shortell
Licensed Master Electrician
Certified Solar Installer
71 Oregon Street
Long Beach N.Y. 11561
Www.thesolarstorehouse.com <http://www.thesolarstorehouse.com>
On Apr 21, 2016, at 11:56 AM, Peter Parrish
<[email protected] <mailto:[email protected]>>
wrote:
I am working with a customer who is doing a complete remodel and
addition to his house: stripped to the open studs and floor joists,
and rafters. Not a wire in the house. We have designed a 14.4 kWp PV
system with 16 kW of storage for backup and load shifting. The main
panel, inverters, critical load subpanel and batteries are all going
to be in the garage which is about 45 feet from the house. The
customer and I have identified the critical loads.
The GC is running conduit from the main house to the garage. I have
been given seven (7) 1-1/2” PVC conduits, and I am currently doing
conduit fill, ampacity and voltage drop calculations for the branch
circuits that represent the critical loads.
So I have two questions:
(1)Should I stick to a <1% voltage drop on all circuits?
(2)Do 120 V neutrals count as current carrying conductors? I think
they do, but the electrician stated quite emphatically that they
didn’t. I thought that the derating calcs for CCCs were based solely
on ohmic losses and phasing was not taken into account.
Does the NEC provide guidance on this latter situation?
-Peter Parrish
Peter T. Parrish, Ph.D.
President, SolarGnosis
1107 Fair Oaks Ave.
Suite 351
South Pasadena, CA 91030
(323) 839-6108
[email protected] <mailto:[email protected]>
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