[RE-wrenches] White wire for DC- after ground fault breaker
Kent Osterberg
kent at coveoregon.com
Sat Jun 13 21:21:55 EDT 2020
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 <brian at solarenergy.org
> <mailto:brian at 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 <greg at remotepowerinc.com
> <mailto:greg at 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<jj at aprsworld.com <mailto:jj at aprsworld.com>>
> > To: RE-wrenches<re-wrenches at lists.re-wrenches.org
> <mailto:re-wrenches at lists.re-wrenches.org>>
> > Subject: [RE-wrenches] White wire for DC- after ground fault breaker
> > Message-ID:
> >
> <CAFWEuYVMACXebixHtyRVYQ5Xnmaur=UgTv6Etu5TNEpm00nhoA at mail.gmail.com
> <mailto:UgTv6Etu5TNEpm00nhoA at 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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