[RE-wrenches] A related question - Individual AC conductors through separate conduits

Wed Nov 20 10:31:29 PST 2013

Allan,

You might also interpret 300.3(B) as requiring all conductors of the same
circuit to be located in the same conduit.

(B) Conductors of the Same Circuit. All conductors of the same circuit and,
where used, the grounded conductor and all equipment grounding conductors
and bonding conductors shall be contained within the same raceway, auxiliary
gutter, cable tray, cablebus assembly, trench, cable, or cord, unless
otherwise permitted in accordance with 300.3(B)(1) through (B)(4).

-Glenn

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Allan
Sindelar
Sent: Wednesday, November 20, 2013 1:05 PM
To: August Goers; RE-wrenches
Subject: Re: [RE-wrenches] A related question - Individual AC conductors
through separate conduits

August,
Yes, that's relevant to my question. All metal boxes are grounded at both
ends by existing EGCs. Only the PVC conduit is not. So when I read section
250.110 as you have cited, "all equipment fastened in place with exposed
non-current carrying metal parts likely to become energized needs equipment
grounding" is covered correctly.

This is not a huge deal - it's not difficult to pull the #4 out and add an
EGC. I'm just trying to find the appropriate Code reference for an oddball
situation. Thank you.
Allan

Allan Sindelar
 <mailto:Allan at positiveenergysolar.com> Allan at positiveenergysolar.com
NABCEP Certified PV Installation Professional
NABCEP Certified Technical Sales Professional
New Mexico EE98J Journeyman Electrician
Founder, Positive Energy, Inc.

A Certified B CorporationTM
3209 Richards Lane
Santa Fe, New Mexico 87507
505 424-1112 office 780-2738 cell
www.positiveenergysolar.com <http://www.positiveenergysolar.com/> 

On 11/20/2013 10:44 AM, August Goers wrote:

Hi Allan,

Per NEC 250.110 all equipment fastened in place with exposed non-current
carrying metal parts likely to become energized needs equipment grounding.
There are some conditions and exceptions listed in the code so you might
want to check through that section and apply it to your situation. If you
had used metallic conduit such as EMT then the raceway itself would count
for equipment ground. However, since it sounds like you have non-metallic
conduit you do indeed need a equipment ground wire sized per table 250.122.
My general rule of thumb is that all metal boxes and raceways need equipment
ground, period. We run equipment ground conductors even in EMT because there
is a chance that fittings will loosen over time. 

Anyway, that's my take.

Best,

August

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Allan
Sindelar
Sent: Tuesday, November 19, 2013 3:34 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] A related question - Individual AC conductors
through separate conduits

Wrenches,
I need similar advice, please, especially a Code section citation.

In 2005 we installed an Outback system for a new home in town that was
designed and installed to be a grid-backup solar home. It was, in essence, a
stand-alone system to run most of the home with the utility serving the
backup generator's role, both to provide backup charging when needed and to
run a few specific loads. The home was built with two breaker panels side by
side, with the PV system wired between them. The meter pedestal was 150'
away at the edge of the street. The array was small at 1.32 kW.

Around 2007 the interconnection terms were quite good and we converted this
system into a grid-intertied system. Doing this involved replacing the early
Outback FX2024 with a GVFX3524. We also had to run an additional #4
conductor from the system (inverter AC interactive output) to the meter
pedestal in order to carry interactive sell-back energy to a REC meter,
which had to be located next to the revenue meter. We ran this single
conductor in 1" PVC conduit with no other conductor. Given that all AC
neutrals were properly bonded, that the conduit was non-conductive, and that
all metal parts were properly bonded, we didn't run an EGC with this single
THWN. We were permitted and and passed inspection.

Now we are adding an additional 1.3 kW of PV to the system, which requires
full permit process, of course. And in the ensuing years the home has been
annexed into the city, with its reputation for toughness in regards to Code
compliance. Our design team tells me that we must pull that #4 out and
repull it with an EGC, simply because every current-carrying conductor must
have a grounding conductor as well. 

My question: What Code section applies here? Is an EGC always required in
conduit carrying a single current-carrying conductor? 

We're trying to have our ducks in a row before contacting the inspector, and
have never dealt with this particular situation before.
Thank you,
Allan

Allan Sindelar
 <mailto:Allan at positiveenergysolar.com> Allan at positiveenergysolar.com
NABCEP Certified PV Installation Professional
NABCEP Certified Technical Sales Professional
New Mexico EE98J Journeyman Electrician
Founder, Positive Energy, Inc.

A Certified B CorporationTM
3209 Richards Lane
Santa Fe, New Mexico 87507
505 424-1112 office 780-2738 cell
www.positiveenergysolar.com <http://www.positiveenergysolar.com/> 

On 11/19/2013 11:22 AM, Dave Click wrote:

300.3(B) Conductors of the Same Circuit. All conductors of the same circuit
and, where used, the grounded conductor and all equipment grounding
conductors and bonding conductors shall be contained within the same
raceway, auxiliary gutter, cable tray, cablebus assembly, trench, cable, or
cord, unless otherwise permitted in accordance with 300.3(B)(1) through
(B)(4) [which don't help here]. 

On 2013/11/19, 12:38, August Goers wrote:

Hi All -

On a related note, I've become good friends with some of the inspectors in
San Francisco and they called me yesterday with a question. Is it okay to
run individual DC conductors through EMT for wire management purposes? We
have always run paired positive and negative conductors in conduit so the
question had never occurred to me. Obviously, you have to bond both ends of
the conduit if it is over 250 v. I know that AC would have induction issues
with running individual conductors but I'm not sure with DC.

Thanks,

August

August Goers

Principal

Luminalt Energy Corporation

o: 415.641.4000

m: 415.559.1525

www.luminalt.com

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of William
Miller
Sent: Monday, November 18, 2013 11:33 PM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] PV Wiring methods

Bill:

There is no need to stuff MC4 cables into standard conduit.  You can either
slot the pipe using our easy method or install bulkhead type connectors.
The connectors are readily available.  I get them from PV Cables in Northern
California..

Wire routing problems and some solutions can be found on our web-site:

http://millersolar.com/MillerSolar/practices/PV_wiring/_PV_Wiring2.html

Since the industry won't provide wire management solutions, we are making
our own.  Questions:  Just write or call.

William Miller

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of frenergy
Sent: Thursday, November 14, 2013 7:46 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] PV Wiring methods

William, Bill....from another Bill,

        Two things:  For the rest of us (maybe it's just me?!) that's still
trying to figure out how (or why) to stuff a MC4 connector into conduit and
my hesitation in using SS wire ties for fear of the sharp edges cutting or
chaffing into cables, I'm open for advice. Any wire I use on the roof is
rated for that type of service and I have some off-grid systems that have
been in the sun for some 25 years where the wire still looks nearly new even
when flexing it to look for checking/cracks.  It seems the wire/insulation
can take it, thus it seems like the key to "wire management is to keep the
wire from moving and off the roof, secured to the racking, thus not
compromising the insulation. 

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