[RE-wrenches] Guarding against live parts 690.7 (D)
Ray Walters
ray at solarray.com
Thu Sep 10 16:04:59 PDT 2015
I'm confused again. Do we need to guard ground mount arrays or not? I
thought it was clear that we did need to guard the array wiring.
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 9/9/2015 6:46 PM, William Miller wrote:
>
> Bill:
>
> How right you are. I spoke with Mike Stoker of the County of San Luis
> Obispo today and he told me that both you and Mike Holt are saying
> that guards are not required on readily accessible wiring. I sent him
> your recent email to me on the subject. He may be in touch. If you
> want to write him, his email is mstoker at co.slo.ca.us
> <mailto:mstoker at co.slo.ca.us>.
>
> I looked on Mike Holt’s site and did not see anything from Mike about
> wire guarding. I wrote to Mike and asked him directly. I will let
> you know what I learn.
>
> William
>
> 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
> <mailto:re-wrenches-bounces at lists.re-wrenches.org>] *On Behalf Of
> *billbrooks7 at sbcglobal.net <mailto:billbrooks7 at sbcglobal.net>
> *Sent:* Saturday, September 05, 2015 2:21 PM
> *To:* 'RE-wrenches'
> *Subject:* Re: [RE-wrenches] Guarding against live parts 690.7 (D)
>
> William,
>
> You can always quote me to an AHJ, as long as I actually said it or
> wrote it.
>
> I have been accused of saying all kinds of things that I never
> said—people just misunderstood what I said and “quoted” me incorrectly.
>
> All the best—and stay safe. Always tragic to hear of
> electrocutions—most are so preventable as this one clearly was. Never,
> ever assume that a circuit is off. I know you warned against inductive
> sensors, but they should still be used as one of several methods to
> detect voltage. I just watched a video about a guy who thought he was
> testing a 480V circuit when it was really a 12kV circuit. The fireball
> caught him on fire and burned him to death. The meter was the problem.
> An inductive sensor would have saved his life. There is no single
> method for safety.
>
> Bill.
>
> *From:*RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org]
> *On Behalf Of *William Miller
> *Sent:* Friday, September 04, 2015 2:37 PM
> *To:* RE-wrenches <re-wrenches at lists.re-wrenches.org
> <mailto:re-wrenches at lists.re-wrenches.org>>
> *Subject:* Re: [RE-wrenches] Guarding against live parts 690.7 (D)
>
> Bill:
>
> I apologize that I assumed incorrectly. Thank you for your
> assessment. May I quote you to our AHJ?
>
> Sincerely,
>
> William
>
> 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
> <mailto:re-wrenches-bounces at lists.re-wrenches.org>] *On Behalf Of
> *billbrooks7 at sbcglobal.net <mailto: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]
> *On Behalf Of *William Miller
> *Sent:* Friday, September 04, 2015 12:09 PM
> *To:* RE-wrenches <re-wrenches at lists.re-wrenches.org
> <mailto: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
>
> 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
> <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
>
> 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
> <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
> <mailto: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 <http://www.northwindre.com>
>
>
>
> NABCEP Certified PV Installation Professional™
>
> NABCEP Certified PV Technical Sales Professional™
>
> State of WI: Master Electrician
>
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