Re: [RE-wrenches] EMT in attic
Nick, what the AHJ is telling you may actually be in reference to 250.97; for most PV output circuits (yes these are necessarily dc) this bonding requirement applies since array VOC 250 VDC. As Kent just pointed out, these dc conductors clearly don't meet the NEC definition of a service. 250.97 Bonding for Over 250 Volts. For circuits of over 250 volts to ground, the electrical continuity of metal raceways and cables with metal sheaths that contain any conductor other than service conductors shall be ensured by one or more of the methods specified for services in 250.92(B), except for (B)(1)... followed by an exception. Seems that FMC is OK as an EGC if your conductors have 20A OCPDs, which I imagine you do, but that FMC also can't be longer than 6' (see 250.118(5)). So I think your AHJ is probably right and I just learned something. If you're running a separate EGC anyway, you may want to ask why this bonding business is so important-- but I don't have an NEC reference on this to help you argue this. Maybe the AHJ would allow you to just run MC cable as the 2011 NEC allows. John Wiles is awesome. Someone on this list had to say it. DKC On 2012/11/8 23:22, Nick Vida wrote: Hi Wrenches, Thanks for you comments. Fun for the day is hearing they want to apply section 230 about service conductors and say that flex is not a metallic raceway because it is no good for bonding. They are defining the pv source circuits as a service. I am getting a distinct Wiles vibe here. I find it so annoying when they try to put out these distinctions with no code, no city ordinance and not even an internal memo, especially when they remain obstinate without going to the trouble to actually legitimize the interpretation. Dan- are the output circuits necessarily DC? I would have to look at NEC for a minute, but it doesn't seem to add up to me right now. Thanks, Nick Vida ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org 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: RE-wrenches@lists.re-wrenches.org 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
Re: [RE-wrenches] EMT in attic
Dave, You are on to something that has been on my mind for years. I believe that FMC inside the building before a disconnect with DC conductors above 250V is allowed by the Code. And I believe the requirement for bonding in 250 applies regardless of whether or not a separate EGC is run in the FMC. The real problem I faced was getting FMC and fittings rated for the job. FMC is available in both Al and steel, thin wall and normal. I always used thick wall steel FMC and fittings that had a set screw clamping mechanism for attaching the adapter to the FMC. I spent time trying to find materials with listing for the purpose but never got to the bottom if it. I have always had a problem when I saw thin wall AL flex being used with twist-in-insert type fittings. Mark Frye On 11/9/2012 5:44 AM, Dave Click wrote: Nick, what the AHJ is telling you may actually be in reference to 250.97; for most PV output circuits (yes these are necessarily dc) this bonding requirement applies since array VOC 250 VDC. As Kent just pointed out, these dc conductors clearly don't meet the NEC definition of a service. 250.97 Bonding for Over 250 Volts. For circuits of over 250 volts to ground, the electrical continuity of metal raceways and cables with metal sheaths that contain any conductor other than service conductors shall be ensured by one or more of the methods specified for services in 250.92(B), except for (B)(1)... followed by an exception. Seems that FMC is OK as an EGC if your conductors have 20A OCPDs, which I imagine you do, but that FMC also can't be longer than 6' (see 250.118(5)). So I think your AHJ is probably right and I just learned something. If you're running a separate EGC anyway, you may want to ask why this bonding business is so important-- but I don't have an NEC reference on this to help you argue this. Maybe the AHJ would allow you to just run MC cable as the 2011 NEC allows. John Wiles is awesome. Someone on this list had to say it. DKC ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org 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
Re: [RE-wrenches] EMT in attic
+1. John Wiles is awesome—and he would never mistake PV source or array circuits for a service. Not only are PV power circuits not a service, but PV systems (inverter output circuits) are not a service. The NEC defines all of this as power production equipment (705.2). By definition a service can only be provided by a serving utility (Article 100). That definition does not apply to PV systems. Having said that, Section 230.82(6) does allow PV systems to connect to the supply side of a service disconnect. But that allowance doesn't magically change the PV system into a service; it is still (parallel) power production equipment. If you're still in the planning phase, Nick, it is a good idea to see if they will allow you to use MC that complies with 250.118(10) according to 690.31(E) in NEC 2011. DCB On Nov 9, 2012, at 7:44 AM, Dave Click wrote: Nick, what the AHJ is telling you may actually be in reference to 250.97; for most PV output circuits (yes these are necessarily dc) this bonding requirement applies since array VOC 250 VDC. As Kent just pointed out, these dc conductors clearly don't meet the NEC definition of a service. 250.97 Bonding for Over 250 Volts. For circuits of over 250 volts to ground, the electrical continuity of metal raceways and cables with metal sheaths that contain any conductor other than service conductors shall be ensured by one or more of the methods specified for services in 250.92(B), except for (B)(1)... followed by an exception. Seems that FMC is OK as an EGC if your conductors have 20A OCPDs, which I imagine you do, but that FMC also can't be longer than 6' (see 250.118(5)). So I think your AHJ is probably right and I just learned something. If you're running a separate EGC anyway, you may want to ask why this bonding business is so important-- but I don't have an NEC reference on this to help you argue this. Maybe the AHJ would allow you to just run MC cable as the 2011 NEC allows. John Wiles is awesome. Someone on this list had to say it. DKC On 2012/11/8 23:22, Nick Vida wrote: Hi Wrenches, Thanks for you comments. Fun for the day is hearing they want to apply section 230 about service conductors and say that flex is not a metallic raceway because it is no good for bonding. They are defining the pv source circuits as a service. I am getting a distinct Wiles vibe here. I find it so annoying when they try to put out these distinctions with no code, no city ordinance and not even an internal memo, especially when they remain obstinate without going to the trouble to actually legitimize the interpretation. Dan- are the output circuits necessarily DC? I would have to look at NEC for a minute, but it doesn't seem to add up to me right now. Thanks, Nick Vida ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org 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: RE-wrenches@lists.re-wrenches.org 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: RE-wrenches@lists.re-wrenches.org 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
[RE-wrenches] EMT in attic - vs FMC vs armored cable
This subject interests me as I had been considering using waterproof metallic armored cable. I can get pre-made cable with just about any number of conductors of any size, sheathed in a flexible metallic layer and then a UV resistant waterproof layer. The stuff is direct burial as well. Buying 4 conductor and ground #8 would handle 95% of my residential work. I could overkill with #6, or 6 conductor, and the savings on all the screwing around with conduit would still make it better. In bulk it's actually about the same price per foot as individually purchased wire and conduit. The thing I like about it is that it eliminates all the cutting, measuring, bending, and pulling, or in the case of PVC, stocking of fittings, measuring, cutting, gluing, and pulling. Just roll it off the reel. The question is, will the AHJ accept it for a 250VDC interior run? Maybe with the right end fittings? Hilton -- Hilton Dier III Renewable Energy Design Partner, Solar Gain LLC 453 East Hill Rd. Middlesex, VT 05602 ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org 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
Re: [RE-wrenches] EMT in attic - vs FMC vs armored cable
Hilton: This is an intriguing concept: The universal PV AC/DC cable. It has a red, black and white #10, a green #8, it's rated for 600 V AC or DC and for wet locations with a metallic cover. I'd buy a roll. Where do we get it? William Miller At 11:54 AM 11/9/2012, you wrote: This subject interests me as I had been considering using waterproof metallic armored cable. I can get pre-made cable with just about any number of conductors of any size, sheathed in a flexible metallic layer and then a UV resistant waterproof layer. The stuff is direct burial as well. Buying 4 conductor and ground #8 would handle 95% of my residential work. I could overkill with #6, or 6 conductor, and the savings on all the screwing around with conduit would still make it better. In bulk it's actually about the same price per foot as individually purchased wire and conduit. The thing I like about it is that it eliminates all the cutting, measuring, bending, and pulling, or in the case of PVC, stocking of fittings, measuring, cutting, gluing, and pulling. Just roll it off the reel. The question is, will the AHJ accept it for a 250VDC interior run? Maybe with the right end fittings? Hilton ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org 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
Re: [RE-wrenches] EMT in attic - vs FMC vs armored cable
Sounds like you are referring to what we refer to around here as teck cable. Very common stuff for industrial applications. Here, pretty much any electrical wholesaler has stock in several configurations. Can be ordered in 2,3,4,5,6... (Not sure the limit extent) number of conductors and in pretty much any awg size and usually comes with an appropriate sized bond. Just have to watch the exposed/visible horizontal runs as it will sag and look sloppy. I'm pretty sure I have some spec sheets if you like. Request them offline. benn Sent from a 'smart' phone, with touch screen keys. Please excuse shortcuts and typos. On 2012-11-09, at 1:37 PM, William Miller will...@millersolar.com wrote: Hilton: This is an intriguing concept: The universal PV AC/DC cable. It has a red, black and white #10, a green #8, it's rated for 600 V AC or DC and for wet locations with a metallic cover. I'd buy a roll. Where do we get it? William Miller At 11:54 AM 11/9/2012, you wrote: This subject interests me as I had been considering using waterproof metallic armored cable. I can get pre-made cable with just about any number of conductors of any size, sheathed in a flexible metallic layer and then a UV resistant waterproof layer. The stuff is direct burial as well. Buying 4 conductor and ground #8 would handle 95% of my residential work. I could overkill with #6, or 6 conductor, and the savings on all the screwing around with conduit would still make it better. In bulk it's actually about the same price per foot as individually purchased wire and conduit. The thing I like about it is that it eliminates all the cutting, measuring, bending, and pulling, or in the case of PVC, stocking of fittings, measuring, cutting, gluing, and pulling. Just roll it off the reel. The question is, will the AHJ accept it for a 250VDC interior run? Maybe with the right end fittings? Hilton ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org 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: RE-wrenches@lists.re-wrenches.org 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
