HI Chris;
As with all things bureaucratic, good intentions can go awry when
actually implemented. Years ago, I was one of the wrenches pushing for
some form of disconnect closer to the power source, or the PV array. I
had no idea it would come back to bite us small off grid folks so hard,
though. I'm not quite for scrapping all of 690.12, but I do think it
needs some serious work. /In or on the building/ needs to be defined
more clearly as 'on the roof'. Ground mounts need a clearer exemption.
The PV disconnect needs to be clearly defined and also clearly stated
that the Rapid disconnect system stops there. The time limit needs to
be bumped up to 90 seconds: no one is going to throw the switch and be
hacking on the roof that fast. The array voltage should be 150 vdc, so
that lower voltage off grid systems could be exempt, and I really think
690.12 should only apply to larger arrays (over 10kW) that have long
exposed runs of conduit (over 10 yards) or that cover more than a
certain percentage of the total roof area. If an array covers one face
of the garage it should be exempt, and if it covers half the total roof,
then it should have Rapid disconnect, for instance. We need to be
sensible, do the fire fighters have a good spot to cut and vent the roof
without electrical hazards or not?
Its interesting how article 690 has morphed from being almost entirely
oriented towards off grid in 99 and 02, to now off grid is barely even
considered. Just look at the lack of thought when they wrote the
definitions for /DC to DC Converters/. The solar industry has been
ready and willing to be thrown under the bus at every turn. I think its
about time we started advocating for our own self interests like all the
other parties involved. This also means that us off grid folks need to
be properly represented, and off grid considered with all code changes.
I think DC coupled PV should have its own section and be separated from
AC coupled PV. The systems are so different that it doesn't make sense
to throw them into the same section. The emergence of article 706 is a
step in the right direction.
Ray Walters
Remote Solar
303 505-8760
On 8/23/18 5:31 PM, cwar...@entech-engineering.com wrote:
I think Rapid Shutdown should be scrapped professionally and
personally. It was ill conceived and ill written. Anyone willing to
join me in a petition to CMP 44 and the like, contact me off list.
To your question directly, you have a ground mounted system and you
are not subject to 690.12 unless your conductors are "in or on
building" which i cannot seem to find what that actually means.
Exempted are buildings that are isolated only for the PV system This
is a big win for installers as almost everyone installs systems like
this....... Right. They used to have a dimension to this, but I
guess that gave installers too much information. This is a stupid Code
addition for roof mounted pv systems, disguised as protecting
Firefighters, but not doing so in reality. The NEC looks politically
compromised by consultants and manufacturers who too advantage of this
fear mongering. No other country with a pv industry has historically
done this. Why are installers not up in arms about this?
This is the NEC reference.
690.12 Rapid Shutdown of PV Systems on Buildings. PV system circuits
installed on or in buildings shall include a rapid shutdown function
to reduce shock hazard for emergency responders in accordance with
690.12(A) through (D).
If your system is ground mounted, you are outside the "altruistic"
intent of 690.12 of protecting Firefighters. Put a initiation device
disconnect switch at the array. Any supporters of RS should chime in
with the support of 690.12 and add clarity and guidance to those of us
who actually install systems and have to deal with this baloney.
690.12 has caused more problems for multimode systems than any
tariffs, which are bad enough. I don' think the industry needs any
more "safe design and installation" assistance from the CMPs involved
with this issue.
Chris Warfel
On 2018-08-23 00:31, Ray wrote:
Greetings fellow wrenches;
I know we have beat this many times but I once again have not been
able to resolve the contradictory information in 690 in regards to
implementing 690.12. As Rebekah Hren pointed out before, the
diagrams shown in Figure 690.1(b) show that the /PV System DC
Circuit/ stops at the /PV Disconnect/. Note 2 says specifically the
'/PV Disconnect separates the PV system from all other systems/'.
But then in the definitions in 690.2 on the next page, the new
definition of a /P//V System DC Circuit/ says that it includes DC to
DC converter output circuits. (which are Solar Edge module level
controls, but could be interpreted as a MPPT battery charge Controller?)
Then 690.12 which only applies to '/PV System circuits in or on
buildings/', says we have to control conductors more than 3 ft after
penetrating the building.
So in my case, I'm looking at a ground mount, and installing an
external lockable disconnect on the wall before it goes into the
building. This will officially be the PV Disconnect. In my
interpretation, I should not need to do any Rapid Shutdown, because
I've essentially prevented the /PV system/ from ever entering the
building at all ( based on the 5th diagram and Note 2) However, I
could see an AHJ claiming I had to do RS all the way to the output
side of the charge controller.
If this were true, could I simply apply RS equipment from the PV
disconnect to the output of the charge controller, or am I back to
module level shutdown for my ground mounted array, or could I build a
tiny building that just housed the PV Disconnect and take the
exemption for '/buildings with the sole purpose of housing PV system
equipment/'?
Essentially the definitions in 690.2 are too broad, and are at odds
with the Figure and Notes of 690.1. They really didn't fix this in
the 2017 code for us lowly off gridders. Charge controllers are
covered by article 706.23___/Charge Control/_, and NOT by 690.12 at
all. IMHO, the charge controller needs to be clearly defined and
differentiated from DC to DC converters like Solar Edge's module
level DC equipment.
I just want to go back to doing solar designs and installations, and
quit acting like an attorney parsing every word of this confusing
code language.
--
Ray Walters
Remote Solar
303 505-8760
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