This brings up another question for me: what really is the difference in the armor between AC and MC, and how come AC isn't being allowed, or is it allowed, but not specifically mentioned, being considered a metal (metallic?) enclosure?
R. Walters [email protected] Solar Engineer On Dec 5, 2009, at 8:45 AM, Dave Click wrote: > I believe that in a Code Corner back in the '05 era, John Wiles had said that > MC cable was OK to use, then in a later Code Corner he says that it isn't; I > thought it was because part of the reason for a metal raceway is physical > protection, and EMT/FMC would be sturdier than MC. But then I looked at the > 2011 Code, which (as it currently stands) will allow MC: > > (E) Direct-Current Photovoltaic Source and Output Circuits Inside a Building. > Where dc photovoltaic source or output circuits from a building-integrated or > other photovoltaic system are run inside a building or structure, they shall > be contained in metal raceways, Type MC metal clad cable that complies with > 250.118(10), or metal enclosures, from the point of penetration of the > surface of the building or structure to the first readily accessible > disconnecting means. The disconnecting means shall comply with 690.14(A), > (B), and (D). [ROP 4-228] > > The new 690.31(E) is about ten times longer than the '08 edition, now > requiring the conduit to be >10" below the surface of the roof (to avoid > firefighting equipment venting the roof) and labeling along that conduit too: > http://www.solarabcs.com/index.php?option=com_docman&task=doc_download&gid=248&&Itemid=72 > > And to save you a lookup: > 250.118 Types of Equipment Grounding Conductors. > The equipment grounding conductor run with or enclosing the circuit > conductors shall be one or more or a combination of the following: > ... > (10) Type MC cable where listed and identified for grounding in accordance > with the following: > a. The combined metallic sheath and grounding conductor of interlocked > metal tape–type MC cable > b. The metallic sheath or the combined metallic sheath and grounding > conductors of the smooth or corrugated tube-type MC cable > > -------- Original Message -------- > Subject: Re: [RE-wrenches] 690.32(E) + MC? > From: R Ray Walters <[email protected]> > To: RE-wrenches <[email protected]> > Date: 2009/12/5 03:28 > >> I think the issue here is 690.32 deals just with 'fittings and >> connectors', not the actual wire or cable. I believe you meant to >> reference 690.31 which says 'all raceway and cable wiring methods >> included in this code....shall be permitted'. But you still have to >> comply with 690.31E which says it needs to be in 'metal raceways or >> metal enclosures' once it enters the building up to the first readily >> accessible disconnect. Looking at article 100, the definition of >> raceway does include flexible metal conduit, so it seems you could >> use metal flex conduit and pull wire, but I know many inspectors >> still won't allow it. Reading up in articles 320 and 330 for AC and >> MC cables, MC doesn't say it's conduit, so it would be out, but AC >> says its enclosed in a 'flexible metallic enclosure'. So now the >> question is: Is metallic the same as metal? (Oh Boy are we splitting >> semantic hairs now.......). Bill or William are the ones to clarify >> better than I on all of this, though. They've been involved in the >> actual writing of the code. IMHO, it seems yet another point to be >> clarified in future additions of the code. Meanwhile to be safe, most >> of us are just running EMT once we penetrate the building. (which >> opens yet another question: when have you penetrated the building? >> above or below the roof flashing?) >> I think I've caused enough trouble for now, >> R. Walters [email protected] Solar Engineer >> On Dec 4, 2009, at 7:47 PM, Darryl Thayer wrote: >>> I have always read metal conduit, The reason being the solar is >>> unfused source circuits, and there is no way for overcurrent >>> protective devices to open. Therefore, the conductors must be >>> protected from starting a fire under conditions of continuous >>> overcurrent. darryl >>> --- On Fri, 12/4/09, [email protected] >>> <[email protected]> wrote: >>>> From: [email protected] <[email protected]> Subject: >>>> [RE-wrenches] 690.32(E) + MC? To: "RE-wrenches" >>>> <[email protected]> Date: Friday, December 4, >>>> 2009, 5:18 PM I did a project a while ago for a supplier / >>>> Installing out fit (who has their in house engineering types), >>>> who told me that either MC or maybe AC cable did comply with >>>> 690.32E. today I'm being told that's not the case, and I can't >>>> seem to put my finger on it ... any pointers? thanks db >>>> Dan Brown President Foxfire Energy Corp. Renewable Energy Systems >>>> (802)-483-2564 www.Foxfire-Energy.com NABCEP #092907-44 >>>> -----Inline Attachment Follows----- >>>> _______________________________________________ List sponsored by >>>> Home Power magazine >>>> List Address: [email protected] >>>> Options & settings: >>>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>>> List-Archive: >>>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >>>> List rules & etiquette: www.re-wrenches.org/etiquette.htm >>>> Check out participant bios: www.members.re-wrenches.org >>> _______________________________________________ List sponsored by >>> Home Power magazine >>> List Address: [email protected] >>> Options & settings: >>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>> List-Archive: >>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >>> List rules & etiquette: www.re-wrenches.org/etiquette.htm >>> Check out participant bios: www.members.re-wrenches.org >> _______________________________________________ List sponsored by >> Home Power magazine >> List Address: [email protected] >> Options & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> List-Archive: >> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >> List rules & etiquette: www.re-wrenches.org/etiquette.htm >> Check out participant bios: www.members.re-wrenches.org > _______________________________________________ > List sponsored by Home Power magazine > > List Address: [email protected] > > Options & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org > > _______________________________________________ List sponsored by Home Power magazine List Address: [email protected] Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
