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> 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> > To: RE-wrenches<re-wrenches@lists.re-wrenches.org> > Subject: [RE-wrenches] White wire for DC- after ground fault breaker > Message-ID: > <CAFWEuYVMACXebixHtyRVYQ5Xnmaur=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/ > -------------- next part -------------- > An HTML attachment was scrubbed... > URL:<http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20200612/5cd338c8/attachment-0001.html> > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > _______________________________________________ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org
