[RE-wrenches] 690.4 (B) ???

[Kirk Herander, VSE]

From: Kirk Herander, VSE [mailto:kirk at vtsolar.com] 
Sent: Sunday, April 10, 2011 10:02 PM
To: 'William Miller'
Subject: RE: [RE-wrenches] 690.4 (B) ???

 

Thanks William,

 

IMO you are right on in your interpretation. I can see no wiggle room for
the inspector because of the definitions in 690.2. So we will see what
happens. BTW, I hope your local inspector reversed themselves when presented
the same "evidence".

 

That said, 690.4(B) tin the 2008 NEC is ridiculously vague. PV
inputs/outputs are not spelled out as DC (which by definition they are).
Does "unless connected" mean unless the pv inputs and outputs are tied
together (and why woudn't they be in a jbox or fused array combiner), or
that the pv inputs and outputs are tied to the "separate" system conductors
in the same raceway?

Is this the most poorly worded paragraph in 690? It seems so right now. Just
got my new 2011 NEC (comments version) but I am without it traveling and can
only hope it's been clarified.

 

Kirk Herander 
Vermont Solar Engineering 
802.863.1202 
NABCEP(tm) Certified Solar Installer 
NYSERDA-eligible Installer 
VT Solar Incentive Program Partner 

  _____  

From: William Miller [mailto:william at millersolar.com] 
Sent: Sunday, April 10, 2011 2:19 AM
To: kirk at vtsolar.com; RE-wrenches
Subject: Re: [RE-wrenches] 690.4 (B) ???

 

Kirk:

When you say inverter combiner, I am confident you mean the device combining
the AC output conductors of multiple inverters.

I got the same jive from an over zealous inspector once, but he and your
inspector are just plain wrong.   Examine and show them the diagram in the
code book of PV source and output conductors (690.2).  These are all DC PV
conductors, not AC conductors, and, assuming the statement in the paragraph
above is correct,  the passage has no application here.  This is a rookie
inspector mistake.

Good luck,

William

PS:  By saying the source and output connectors are connected together, this
is an oblique way of describing the PV combiner, the one point where PV
source and output circuits are connected together.

WM



At 06:10 PM 4/9/2011, Kirk Herander, VSE wrote:

2008 NEC states that:

(B) Conductors of Different Systems. Photovoltaic
source circuits and photovoltaic output circuits shall not be
contained in the same raceway, cable tray, cable, outlet box,
junction box, or similar fitting as feeders or branch circuits
of other systems, unless the conductors of the different systems
are separated by a partition or are connected together.

Can anyone describe and give an example of what "connected together" means
to inverter PV circuits in the same conduit as a branch (load) circuit?

I have a single existing PVC conduit to a barn with an AC load subpanel. I
want to run the output conductors of an inverter combiner panel in the barn
through the same conduit to get to be main building. The fill / derating
calcs work to do this. The inspector says I have to run a new conduit for
the AC inverter combiner because the subpanel feeder and the combiner output
conductors are "not connected". But they are both connected to the main
building panel. Any insight will be appreciated. Thanks. I've also been told
that the NEC 2011 comments on 690.4 (B) clarify this. Can anyone comment?
Obviously I am not mixing DC and AC conductors.



Kirk Herander

William Miller 
Miller Solar
Voice :805-438-5600
email: william at millersolar.com
http://millersolar.com <http://millersolar.com/> 
License No. C-10-773985

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20110411/06fd7fc9/attachment-0004.html>