[RE-wrenches] RSS: Is it necessary?
Christopher Warfel
cwarfel at entech-engineering.com
Tue Feb 18 08:33:47 PST 2025
Well, I think if wiring of a ground mounted system looks like a jungle
gym, then something is wrong.
On 2/18/2025 11:32 AM, Glenn wrote:
> Rarely are AC electrical circuits and equipment placed adjacent to a
> residence in a cleared field where there may be children thinking it
> looks like a jungle gym either...
>
> -Glenn
>
> On Feb 18, 2025 11:23, Christopher Warfel via RE-wrenches
> <re-wrenches at lists.re-wrenches.org> wrote:
>
> I think the 8' rule for this is a little bizarre. I can have ac
> circuits lower than 8' all through my basement, attic and so
> forth, but this barrier requirement for dc conductors that have
> robust jackets and no exposed live connections has been hard to
> justify. Christopher Warfel
>
> On 2/18/2025 12:25 AM, William Miller via RE-wrenches wrote:
>
> Tyrone:
>
> You raise an excellent point. Wire guarding is required on
> ground mount arrays
> <https://millersolar.com/MillerSolar/case_studies/18%20Wire_shielding_on_ground_mounted_PV_arrays/Wire_shielding_on_ground_mounts.html>,
> although the language is vague and the industry does not
> provide many hardware solutions. Also, in our area the
> enforcement
> <https://millersolar.com/MillerSolar/case_studies/18%20Wire_shielding_on_ground_mounted_PV_arrays/SLO_County.html>
> of the code on this practice is non-existent. I suspect this
> is true in many regions. Improvements need to be made.
>
> William Miller
>
> Miller Solar
>
> 17395 Oak Road, Atascadero, CA 93422
>
> 805-438-5600
>
> www.millersolar.com <http://www.millersolar.com/>
>
> CA Lic. 773985
>
> *From:*Tyrone Houck [mailto:tyronehouck at gmail.com]
> *Sent:* Monday, February 17, 2025 8:59 PM
> *To:* william at millersolar.com; RE-wrenches
> *Subject:* Re: [RE-wrenches] RSS: Is it necessary?
>
> As far as ground mounted arrays are concerned there is one
> clear protection mandated by the NEC-the requirement for
> protection from physical damage for all conductors under 8'..
> although this isn't as specific or redundant as rapid shutdown
> requirements, it typically means conduit or at least some kind
> of physical barrier with the intention often referenced as
> protection for children or other unqualified personnel. Not
> sure if that fits into the point you were making but it seems
> worth mentioning.
>
> Sunny Regards,
>
> Tyrone Houck
>
> Oregon Solarworks LLC
>
> CCB #204937 LRT #076
>
> 541-787-1366
>
> tyrone at oregonsolarworks.com
>
>
> On Mon, Feb 17, 2025, 8:42 PM William Miller via RE-wrenches
> <re-wrenches at lists.re-wrenches.org> wrote:
>
> Rebekah:
>
> Thank you for your post.
>
> I have looked at UL3741 over and over. Here is what I
> have gleaned: After module level RSS was mandated there
> was a reevaluation of what voltages were actually
> dangerous for firefighters to be exposed to. It turns out
> 80 VDC is not dangerous and, given all of the
> circumstances for firefighters, exposure to voltages that
> are much higher is safe enough. For some reason I have
> not yet grasped, all of the components need to be matched
> and tested to achieve the hallowed UL3741 rating.
>
> Module level RSS would have presented a big enough
> upheaval in the industry if the equipment needed to comply
> was safe and reliable. There is evidence that in many
> cases it may not be, and that amplifies the skepticism
> many feel about the current solutions, and frankly, any
> future solutions.
>
> It appears the code making panel, when writing the
> original module level RSS requirements, may have been a
> bit “chicken little” about the need for RSS. This
> presents a real credibility issue for code makers. You
> are seeing that credibility problem reflected in the
> discussions here on this forum. Given the back-peddling,
> how can we understand and believe what is really necessary?
>
> Forgive me for being skeptical, but why is it that systems
> with components that have been tested together are
> demonstrably safer than any collection of high quality
> components installed carefully and competently?
>
> In my mind there is another disconnect here (pun
> intended): I can put high voltage, arc producing and
> sustaining wiring on a residential roof or free-standing
> rack and not be required to protect that wiring in any
> specific manner. If I were to install a 240VAC,
> over-current protected and de-energizeable air
> conditioning feeder without conduit, I would be red-tagged
> in a hot second. It may be that fire-fighters in
> protective clothing can withstand voltage above 80VDC, but
> can children not wearing protective “turn-out” clothing?
> Children mess around on roofs and underneath ground-mount
> arrays. Why is the NEC not protecting them by mandating
> specific, listed and tested wire management and guarding
> systems?
>
> Thank you very much and I look forward to your reply.
>
> Sincerely,
>
> William Miller
>
> Miller Solar
>
> 17395 Oak Road, Atascadero, CA 93422
>
> 805-438-5600
>
> www.millersolar.com <http://www.millersolar.com/>
>
> CA Lic. 773985
>
> *From:*RE-wrenches
> [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
> Behalf Of *Rebekah Hren via RE-wrenches
> *Sent:* Monday, February 17, 2025 10:26 AM
> *To:* RE-wrenches
> *Cc:* Rebekah Hren
> *Subject:* Re: [RE-wrenches] RSS: Is it necessary?
>
> I read the wrenches post regularly, as does Brian Mehalic.
> We have both been on CMP-4 (responsible for Article 690)
> for the past three code cycles. I believe a few other CMP
> members probably read too. The International Association
> of Firefighters ("largest and most influential labor
> unions in North America") is represented on CMP-4 and yes
> they do have had a lot to say about this issue.
>
> This is definitely not the first time we have heard that
> certain RS devices are on balance causing more trouble
> than they are curing - though on the other hand some
> manufacturers have certainly figured out how to make safe
> and effective MLPE.
>
>
> I'm a big fan of UL3741, I have been on that UL technical
> committee for about 5 years, and it is the best approach I
> see to expand both off-grid and grid-interactive solutions
> that don't require MLPE for RS. SMA for example is very
> present and working hard at revisions on that standard
> right now. At this point I can't see us having any luck in
> removing 690.12 requirements, except perhaps to replace
> the inside the array boundary voltage limit with only
> option as 3741 listing). So please keep asking
> manufacturers (inverter/rack) to pay attention to UL3741
> and design products to meet the standard.
>
> Best
>
> Rebekah
>
> Licensed Electrical Contractor
> NABCEP Certified Solar PV Installation Professional™ 091209-85
>
> Tel: 336.266.8800
>
> On Mon, Feb 17, 2025 at 10:59 AM Amos Post via RE-wrenches
> <re-wrenches at lists.re-wrenches.org> wrote:
>
> Seems like there has been talk of rescinding RSD
> requirements before on this forum. It also seems that
> it might gain some traction if a dedicated group of
> installers spoke up to the right people (Code Making
> Panel for instance) and put some time into it. I
> agree that at the very least we need reliable RSD
> equipment, and my preference would be less vs more.
>
> Does anybody know if any sort of RSD is being required
> in Europe (not that we follow their electrical
> codes/ideas…just curious)???
>
>
>
> Amos Post
> Integrity Energy
> W 802.763.7023
> C 802.291.2188
> ienergyVT.com <http://www.ienergyvt.com>
>
> Facebook
> <https://www.facebook.com/integrityenergyllp?ref=hl>
>
> On Feb 17, 2025, at 12:30 PM, david quattro via
> RE-wrenches <re-wrenches at lists.re-wrenches.org> wrote:
>
> It seems anecdotal until it happens to you.
>
> My mention of civil disobedience has been answered
> clearly with a “No” in this forum, and I'm fine to
> hear that.
>
> I'll clarify a few points as to why I honestly
> think RSD has been a huge and costly mistake. I
> genuinely think RSD requirements should be terminated
> immediately. If the technology were more robust and if
> it worked consistently I wouldn't protest. But *all*
> the products I've tried have been trouble.
>
> William, respectfully your analogy to seat belts is
> not an appropriate comparison to Rapid Shutdown.
> Seat-belts were required in all new cars starting in
> 1968 because there was statistical evidence supporting
> their tremendous efficacy in saving human life.
> Currently seat belts save about 15,000 lives per year.
>
> Contrasting to RSD: was implemented because of the
> following paranoid fairytale scenario - “A firefighter
> is on a burning solar roof in the daytime, and wearing
> a metal axe at their hip. the poor guy/gal falls into
> live solar glass, and shatters it. The fall is so
> forceful that the heavy-duty fireman’s suit is
> punctured. Electricity conducts through the axe blade,
> through the suit, contacts the skin, and a DC circuit
> is completed through their body.”
>
> As far as I know, this has never happened once
> anywhere on earth. Let’s be honest - this scenario has
> an incredibly low chance of ever happening in all the
> future of humanity. So considering that RSD has never
> helped anyone yet, and probably never will... How many
> fires can be attributed to RSD? How much property
> damage has occurred because of these fires?
>
> The best path to safety for firefighters is by
> preventing fire disasters in the first place. Fires
> spread. Any fire that happens endangers property
> owners, tenants, business owners, neighbors, shoppers,
> bystanders, nearby forests, etc. RSD manufacturers
> aren't doing a good job right now, so we are seeing
> low quality unreliable electronics on the roof. I will
> stick my neck out and admit that installers are not
> always perfect. Humans make mistakes - sometimes in
> initial construction, and sometimes during repair and
> maintenance (i.e. when hunting down failed RSD's which
> happens far more than it should).
>
> At this time, these devices are not being designed
> to withstand reality. When problems happen,
> manufacturers are quibbling. They ignore you until you
> go away, or until you sue them.
>
> This level of "safety" is not important, and in fact
> RSD is causing fires every year.
>
> On Sat, Feb 15, 2025 at 11:38 AM William Miller
> <william at millersolar.com> wrote:
>
> David, Ray:
>
> I have not had any problems with the Tigo RSS
> equipment I have installed and I have had minimal
> problems with optimizers and micro-inverters
> (which are also RSS equipment). Apparently others
> have had failures. We don’t know statically how
> serious this problem is—the posts here are purely
> anecdotal.
>
> We also have not heard from the other side of the
> debate: the fire fighters.
>
> Based on lack of verifiable information I can not
> personally conclude that RSS is all problem and no
> benefit.
>
> To declare that the concept is flawed because the
> equipment available is not reliable is like saying
> we should not be required to install airbags
> because a bad batch of them was manufactured. We
> are seeing problems with the equipment needed to
> implement a safety requirement. That observation
> does not logically conclude the safety requirement
> is not valuable.
>
> I hesitate to dismiss any safety requirement out
> of hand. Safety systems are designed to save
> lives and protect from injury, and most of them
> do. I am glad to have anti-lock brakes, smoke
> detectors and air bags. I have also found it
> quite handy to initiate RSS to allow me to work
> more safely on solar circuits.
>
> Does anyone on this installers forum have contacts
> in the fire-response community that can comment on
> the their side of the issue? If RSD is really
> necessary for safety, then I will do my best to
> install good equipment properly and hold
> manufacturers accountable for shoddy solutions. If
> RSD is not that effective we need to discuss
> undoing the code requirements.
>
> Sincerely,
>
> William Miller
>
> Miller Solar
>
> 17395 Oak Road, Atascadero, CA 93422
>
> 805-438-5600
>
> www.millersolar.com <http://www.millersolar.com/>
>
> CA Lic. 773985
>
> *From:*RE-wrenches
> [mailto:re-wrenches-bounces at lists.re-wrenches.org]
> *On Behalf Of *david quattro via RE-wrenches
> *Sent:* Saturday, February 15, 2025 6:05 AM
> *To:* RE-wrenches
> *Cc:* david quattro
> *Subject:* Re: [RE-wrenches] Tigo inverter experience
>
> RSD is the worst thing to happen to solar. Has
> anyone considered civil disobedience?
>
> I wonder what would happen if all the
> installers banded together and refused, as a
> united industry ‘brotherhood.’ WE are the ones
> stuck with the bullshit in the aftermath.
>
> I’m not being snarky here , this a genuine
> question to the group: Does anyone have _good_
> experience with RSD? i.e. you’re really glad RSD
> was there, and you genuinely feel safer? you’re
> glad and happy to comply with this code and you
> look forward to continuing to use RSD for the rest
> of your career?
>
> On Fri, Feb 14, 2025 at 3:40 PM Ray Walters via
> RE-wrenches <re-wrenches at lists.re-wrenches.org> wrote:
>
> it seems silly that we are required to install
> these extra pieces of equipment for added
> "safety", that are actually a fire hazard on
> the roof. Just to survey again: how many homes
> have been saved by RSD? How many fire fighters
> have actually actuated the RSD system, so that
> they could hack through the array to vent the
> roof?
>
> I think it should only be required if you have
> covered so much of the roof with PV, that the
> fire dept can't access uncovered roof to do
> their venting. The whole premise of RSD is
> flawed. IMHO, its just another effort to
> block the wider adoption of solar.
>
> When it comes to off grid, RSD causes such a
> decrease in reliability to amount to a
> decrease in safety, due to possible loss of
> communications, water, and heat. Add the fire
> hazard and RSD is really not making our
> customers' lives better.
>
> Ray Walters
> Remote Solar
>
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> --
> Christopher Warfel, PE
> ENTECH Engineering, Inc.
> PO Box 871, Block Island, RI 02807
> (401) 447-5773
>
>
--
Christopher Warfel, PE
ENTECH Engineering, Inc.
PO Box 871, Block Island, RI 02807
(401) 447-5773
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