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

Christopher Warfel cwarfel at entech-engineering.com
Tue Sep 15 13:20:13 PDT 2015


How many basements, utility rooms etc. have conductors that fail the 
ground mounted solar array test?  I hope the live parts is what is 
protected and not the conductors themselves.

On 9/10/2015 7:32 PM, William Miller wrote:
> Ray:
>
> I apologize but I thought this discussion was off-line.
>
> Mike Holy and everyone but apparently our local AHJ agree: wire 
> guarding is required.
>
> William
>
>
>
> On Sep 10, 2015, at 4:04 PM, Ray Walters <ray at solarray.com 
> <mailto:ray at solarray.com>> wrote:
>
>> 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
>>>
>>> <mime-attachment.jpg>
>>> 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> 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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-- 
Christopher Warfel, President
ENTECH Engineering, Inc.
PO Box 871, Block Island, RI 02807
401-466-8978

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