[RE-wrenches] RSS: Is it necessary?
Christopher Warfel
cwarfel at entech-engineering.com
Tue Feb 18 13:30:36 PST 2025
Is there a NEC reference for that you know of?, as I see Romex brought
down to switches very often, and I've not found a reference prohibiting
that. As far as a ground mounted solar system being climbed on,
anything is possible, but hopefully trees are of more interest. Thank
you, Chris
On 2/18/2025 11:38 AM, Tyrone Houck wrote:
>
> My understanding of code is that all circuits need to be protected
> from physical damage. It's the same with AC circuits in an unfinished
> garage..can't have exposed romex under 8' in that scenario either.
>
>
>
> On Tue, Feb 18, 2025, 8:34 AM Christopher Warfel via RE-wrenches
> <re-wrenches at lists.re-wrenches.org> wrote:
>
> 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>
>> <mailto: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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Christopher Warfel, PE
ENTECH Engineering, Inc.
PO Box 871, Block Island, RI 02807
(401) 447-5773
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