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@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: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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