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:tyroneho...@gmail.com]
*Sent:* Monday, February 17, 2025 8:59 PM
*To:* will...@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
tyr...@oregonsolarworks.com
On Mon, Feb 17, 2025, 8:42 PM William Miller via RE-wrenches
<re-wrenches@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-boun...@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@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@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
<will...@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-boun...@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@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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