[RE-wrenches] Guarding against live parts 690.7 (D)

William Miller william at millersolar.com
Fri Sep 4 14:36:43 PDT 2015


Bill:



I apologize that I assumed incorrectly.  Thank you for your assessment.
May I quote you to our AHJ?



Sincerely,



William





[image: Gradient Cap_mini]
Lic 773985
millersolar.com <http://www.millersolar.com/>
805-438-5600



*From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
Behalf Of *billbrooks7 at sbcglobal.net
*Sent:* Friday, September 04, 2015 12:59 PM
*To:* 'RE-wrenches'
*Subject:* Re: [RE-wrenches] Guarding against live parts 690.7 (D)



William,



I’m shocked and offended (a tiny bit) that you would prejudice yourself to
not agree with me ;-).



First of all I have been heavily involved in the revising of the language
in 690.31(A) to make it clear that we cannot walk up and touch cables
operating at 600V. The term guarded is a defined term:



*Guarded. *Covered, shielded, fenced, enclosed, or otherwise

protected by means of suitable covers, casings, barriers,

rails, screens, mats, or platforms to remove the likelihood

of approach or contact by persons or objects to a point

of danger.



A fence actually does not prevent ready access (unless it does not have a
gate), but the term guarded fixes that problem. The guarding means has to
be approved by the AHJ, but many methods have been employed including
mounting lattice work around the backside of fixed ground-mounted systems.



Fences are best used for larger systems (over 50-100kW) whereas other
methods—albeit labor intensive—are generally preferred for smaller
installations (under 100 kW)



No intelligent person would disagree with this proper interpretation of the
NEC—including you.



Bill.





*From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org
<re-wrenches-bounces at lists.re-wrenches.org>] *On Behalf Of *William Miller
*Sent:* Friday, September 04, 2015 12:09 PM
*To:* RE-wrenches <re-wrenches at lists.re-wrenches.org>
*Subject:* Re: [RE-wrenches] Guarding against live parts 690.7 (D)



Ray:



1.    Why no fence?  Aesthetics.  Also costs may be a wash by the time you
mobilize a fencing contractor.

2.    I’d apply the same requirements to a fence as one would to an
uncovered swimming pool.  There are the same consequences if a child ends
up in the wrong place.

3.    Why bother?

We figure the expense will decrease as we figure better design and
implementation.  Hasn’t yet.

We care about safety.  I figure we, as an industry, will kill a child by
electrocution someday—it is a matter of probability.  I hope it won’t be on
one of our jobs.

We hope, in some small way, we influence the industry to improve.

4.    The industry has not developed solutions because there is no demand.
There is no demand because AHJs don’t enforce the code.



Thanks for the compliment.  We have several new designs not yet featured on
the web site. Check back next time this comes up.



William



PS:  I am curious what Bill Brooks take on this is, but I don’t think I
will agree with his interpretation.



W





[image: Gradient Cap_mini]
Lic 773985
millersolar.com <http://www.millersolar.com/>
805-438-5600



*From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
Behalf Of *Ray Walters
*Sent:* Friday, September 04, 2015 11:37 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Guarding against live parts 690.7 (D)



WilIiam;

 checked out your guards on your website, that looks really clean, but also
like a lot of work and expense.  I'm still so surprised manufacturers are
not offering an option like that to their frame systems.
My question: how come you didn't just fence the array?  Shading issues on
the south?
If fencing, what height of fence is considered adequate?  4 ft?  6 ft?

R.Ray Walters

CTO, Solarray, Inc

Nabcep Certified PV Installer,

Licensed Master Electrician

Solar Design Engineer

303 505-8760

On 9/4/2015 9:44 AM, William Miller wrote:

Gary:



I think the issue of PV wiring behind module that are readily accessible is
addressed in (2014) 690.31:



*Where PV source and output circuits operating at maximum*

*system voltages greater than 30 volts are installed in*

*readily accessible locations, circuit conductors shall be*

*guarded or installed in a raceway.*



I am not sure what application the original poster had in mind, but this is
the question I think you are asking.  The interpretation to 690.31 seems
clear to me:  No one should be able to touch the conductors without
resorting to a ladder, opening a locked gate or removing a protective
panel.  Readily accessible is defined thusly:



*Capable of being *

*reached quickly for operation, renewal, or inspections*

*without requiring those to whom ready access is requisite*

*to actions such as to use tools, to climb over or remove*

*obstacles, or to resort to portable ladders, and so forth.*



Implementing this is harder than it might seem.  Lacking a fence, the
installer must either use the flimsy solar-scrim product or fabricate his
or her own shielding.  We have put a fair amount of effort towards this.
See link
<http://www.millersolar.com/MillerSolar/practices/PV_wiring/Wire_shielding/_Wire%20Shielding_history.html>
.





William









[image: Gradient Cap_mini]
Lic 773985
millersolar.com <http://www.millersolar.com/>
805-438-5600



*From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
Behalf Of *gary easton
*Sent:* Friday, September 04, 2015 2:22 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Guarding against live parts 690.7 (D)



Bill

Are you  saying there is no requirement to shield wires on a ground array?

On Friday, September 4, 2015, <billbrooks7 at sbcglobal.net> wrote:

Craig,



This one is easy to misinterpret. You missed the words “live parts”. This
has been removed from the 2017 NEC because it is actually referring to load
circuits being fed directly by a PV system on the dc side. All references
to loads and batteries are being removed from 690.



This is a complete non-issue.



Bill.



*From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org
<javascript:_e(%7B%7D,'cvml','re-wrenches-bounces at lists.re-wrenches.org');>]
*On Behalf Of *Craig Gerald Buttke
*Sent:* Thursday, September 03, 2015 11:44 AM
*To:* re-wrenches at lists.re-wrenches.org
<javascript:_e(%7B%7D,'cvml','re-wrenches at lists.re-wrenches.org');>
*Subject:* [RE-wrenches] Guarding against live parts 690.7 (D)





How is everyone handling 690.7 (D)

*Circuits over 150 Volts to Ground. *In one- and two- family dwellings,
live parts in photovoltaic source circuits and photovoltaic output circuits
over 150 volts to ground shall not be accessible to other than qualified
persons while energized.



If you have a commercial (non one or two-family dwelling) are you screening
your ground mount arrays to keep people from touching live conductors PV
wires)?

Thanks for your thoughts

-- 

Yours in Solardarity,



Craig Gerald Buttke



M:(715) 630-1227

O:(715) 630-6451

F:(715) 952-4501



North Wind Renewable Energy, LLC

1626C W Pearl Street

Stevens Point, WI 54481



www.northwindre.com



NABCEP Certified PV Installation Professional™

NABCEP Certified PV Technical Sales Professional™

State of WI: Master Electrician


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