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
<[email protected]>
<mailto:[email protected]> 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:[email protected]]
*Sent:* Monday, February 17, 2025 8:59 PM
*To:* [email protected]; 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
[email protected]
On Mon, Feb 17, 2025, 8:42 PM William Miller via
RE-wrenches <[email protected]> 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:[email protected]]
*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 <[email protected]> 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 <[email protected]>
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
<[email protected]> 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:[email protected]]
*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
<[email protected]> 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
_______________________________________________
List sponsored by Redwood Alliance
Pay optional member dues here: http://re-wrenches.org
List Address: [email protected]
Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
There are two list archives for searching. When
one doesn't work, try the other:
https://www.mail-archive.com/[email protected]/
http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
http://www.re-wrenches.org/etiquette.htm
Check out or update participant bios:
http://www.members.re-wrenches.org
_______________________________________________
List sponsored by Redwood Alliance
Pay optional member dues here: http://re-wrenches.org
List Address: [email protected]
Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
There are two list archives for searching. When
one doesn't work, try the other:
https://www.mail-archive.com/[email protected]/
http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
http://www.re-wrenches.org/etiquette.htm
Check out or update participant bios:
http://www.members.re-wrenches.org
_______________________________________________
List sponsored by Redwood Alliance
Pay optional member dues here: http://re-wrenches.org
List Address: [email protected]
Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
There are two list archives for searching. When one
doesn't work, try the other:
https://www.mail-archive.com/[email protected]/
http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
http://www.re-wrenches.org/etiquette.htm
Check out or update participant bios:
http://www.members.re-wrenches.org
_______________________________________________
List sponsored by Redwood Alliance
Pay optional member dues here:http://re-wrenches.org
List Address:[email protected]
Change listserver email address & settings:
http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
There are two list archives for searching. When one doesn't work,
try the other:
https://www.mail-archive.com/[email protected]/
http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
List rules & etiquette:
http://www.re-wrenches.org/etiquette.htm
Check out or update participant bios:
http://www.members.re-wrenches.org
--
Christopher Warfel, PE
ENTECH Engineering, Inc.
PO Box 871, Block Island, RI 02807
(401) 447-5773
