William,
This is new for the 2017 code:
2017 NEC 690.13(D) An equipment disconnecting means shall simultaneously
disconnect all current carrying conductors that are not solidly
grounded. Yet Schneider, Outback, Midnite, Magnum, and ... all still
have a single PV wire disconnected at the charge controller in their panels.
As far as fusing both conductors goes, most PV circuit over current
protection devices are selected so that they can never be tripped by the
PV system. Adding another over current device in the non-solidly
grounded conductor would be redundant. In a combiner box, a fault in one
string can be back fed by many strings and thus trip an over current
device, if the array is solidly grounded or if accidentally grounded and
the ground fault detection scheme doesn't detect it. And even in a
combiner box an current device in the non-solidly grounded conductor
would be redundant.
Kent Osterberg
Blue Mountain Solar
On 6/15/2020 12:24 PM, William Miller wrote:
Wrenches:
Well now that the NFPA has acknowledged that GFDI protected circuits
do not solidly ground the “grounded“ conductor, and we know they can’t
be white in color, it begs the next question: Should these
sort-of-grounded grounded conductors be switched and over-current
protected?
The manual for the Schneider charge controller shows the negative (or
referenced) switched on one page and not switched on another. Outback
FM 100 manual shows the negative not switched.
Anyone have an argument either way?
William Miller
www.millersolar.com
On Jun 13, 2020, at 6:21 PM, Kent Osterberg <k...@coveoregon.com> wrote:
James,
Here's the code reference: 2017 690.31(B)(1). Only solidly grounded
PV system conductors shall be marked in accordance with 200.6 (white
or gray).
Kent Osterberg
Blue Mountain Solar
On 6/13/2020 5:56 PM, James Jarvis wrote:
Brian, thank you very much. With your hint of "functional ground" I
can clearly see that I am not allowed to have those be white wires.
Now time for me to incur the full wrath by daring to question the
infinite wisdom of the "highly qualified individual" from the state.
(all kinds of fun stuff from this guy. Got another violation for
having a donut type current transformer over a line voltage wire. He
said that wasn't allowed.)
Thank you,
-James Jefferson Jarvis
APRS World, LLC
+1-507-454-2727
(Sent from my phone. My apologies for spelling errors and brevity.)
On Sat, Jun 13, 2020, 17:41 Brian Mehalic <br...@solarenergy.org
<mailto:br...@solarenergy.org>> wrote:
Change in 2017 to “functional grounded” was to clarify this -
it’s not solid when it is thru a fuse or breaker than can be
interrupted either in the event of a ground-fault or if the
breaker is intentionally opened. 2017 makes it clear that there
are very few solidly grounded systems (2 or less PV source
circuits, not touching a building the only case it is allowed).
Pardon any incorrect language as I don’t have my code book, but
I do think the 2017 NEC® makes it very clear, including in the
definition of function grounded, that those conductors cannot be
white or gray, regardless of if the system has a
transformer-based or TL inverter or a CC with integrated or an
external GF breaker/fuse.
Brian
> On Jun 13, 2020, at 3:05 PM, greg egan
<g...@remotepowerinc.com <mailto:g...@remotepowerinc.com>> wrote:
>
> Jim, Hope all is well with you and yours. on white wires in
circuits, In 3 ph. circuits you can get killed breaking into a
neutral that's common to other circuits. One example, working
on 277 lighting, you throw the breaker or light switch on the
one circuit you're working so the hot isn't hot anymore. It's
standard practice for 3 ph. lighting ckts to share a neutral.
The white wire in your ckt is wire nutted in the j-box up in the
ceiling to the common neutrals. Those neutrals are hot to ground
when their respective ckts are hot and they're carrying current.
>
> Just thought it was worth mentioning on this list that there's
no hard fast rule that all white wires are dead. It depends on
the ckt.
>
> Best,
> Greg Egan
> Remote Power Inc.
>
>
> Message: 11
> Date: Fri, 12 Jun 2020 15:17:19 -0500
> From: James Jarvis<j...@aprsworld.com <mailto:j...@aprsworld.com>>
> To: RE-wrenches<re-wrenches@lists.re-wrenches.org
<mailto:re-wrenches@lists.re-wrenches.org>>
> Subject: [RE-wrenches] White wire for DC- after ground fault
breaker
> Message-ID:
>
<CAFWEuYVMACXebixHtyRVYQ5Xnmaur=ugtv6etu5tnepm00n...@mail.gmail.com
<mailto:ugtv6etu5tnepm00n...@mail.gmail.com>>
> Content-Type: text/plain; charset="utf-8"
>
> Hello Wrenches,
>
> I have an off-grid install where I was recently red-tagged by
the state
> inspector. System is 24 volt with battery, Magnum inverters,
some Magnum
> charge controllers, and a Morningstar charge controller. It is
permitted
> under NEC 2017.
>
> One of the inspectors issues was that my DC- conductors to the
array /
> rapid shut down box are black color. He wants them to be white
because he
> says they are solidly grounded. I reason that they are only
solidly
> grounded when they are solidly grounded. As soon as the ground
fault
> protection breaker opens, they are floating at array voltage.
I think it is
> misleading and unsafe to have a white conductor that can have
hundreds of
> volts of potential on it when a breaker trips.
>
> I haven't dug into the code yet. I'm just working on the logic
that one of
> my mentors put into me which is white wires better not have
voltage
> potential on them. "That's the sort of sh*t that kills
electricians" is
> what he repeatedly said ... and it's stuck with me.
>
> Thoughts? I'm backed into the corner with the state, so I will
be changing
> them to white even if it is unsafe ... unless I have some code
backing.
>
> <rant>Changing the wires to white will get interesting up on
the roof. I
> wonder if they want me to cut off the black MC on the modules
and replace
> them with white? This is mostly just an exercise in the State
of Minnesota
> only wanting to know about and allow micro inverters. They
brought in a
> state inspector from three hours away who kept repeating that
he was a
> "highly qualified individual", but was unable to identify or
recognize a
> charge controller. He kept referring to the charge controllers as
> inverters.</rant off>
>
> Thanks,
>
> -James Jarvis
> APRS World, LLC
> +1-507-454-2727
> http://www.aprsworld.com/
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