Re: [RE-wrenches] Assembly Protects Conductors?
Ray, I can't follow you all the way down that path. Is an insulated wire conductor permitted to be use at 100% of it's rating under continuous operation? No. The ampacity is reduced and the conductor must be up-sized. Hence, for a defined load (Isc * 1.25), under continious operation, the conductor must be upsized to match (defined load * 1.25). I don't see how this can be changed by simply changing the nature of the OCP. I think the point of this exception is to allow cost savings by allow assemblies and OCP devices with lower ratings. The exception does not apply to every element of the circuit (the conductors) but only to the 100% rated assemblies and OCP themselves. What am I missing? Thanks, Mark On 8/22/2014 6:14 PM, Ray Walters wrote: Most combiner boxes, DC rated breakers, and DC rated fuses and fuse holders we use today, qualify as assemblies for the 100% exception (Outback, Midnite, etc.) so you only have to size the OCP by 125% of short circuit current rating for edge of cloud effects. Since the conductor is sized based on the overcurrent protection, you do not need to size it to 156% of the short circuit current rating, if you take advantage of 100% duty rated breakers and combiners. Also, recombiners are still basically combiner boxes, and so all the same rules apply. The additional 125% is only for breakers that are rated at 80% (most AC breakers for example) . For DC, the only time you would size for the full 156% would be if you were using something like an old QOU breaker, and those aren't rated for high enough voltage for today's arrays anyway. I'm not aware of any other readily available DC rated breaker that is NOT 100% duty rated. Some RK5 fuse assemblies may also not be 100% rated. (Wrench Colleagues please correct me on this) Basically unless you are using surplus equipment from the stone age, (no offense to my fellow stone age wrenches) you only need to oversize the conductors by 125%. By the time you apply all the other applicable deratings for conduit fill, terminals rated at 75 C, and direct sunlight on roofs (table 310.15B3c) and consider voltage drop, you really don't need to keep oversizing. R.Ray Walters CTO, Solarray, Inc Nabcep Certified PV Installer, Licensed Master Electrician Solar Design Engineer 303 505-8760 On 8/22/2014 2:34 PM, ma...@berkeleysolar.com wrote: Folks, In looking at a circuit breaker based re-combiner for the first time, I am now pondering the meaning of the Exception below: NEC 2014 690.8 (B) Conductor Ampacity. PV system currents shall be considered to be continuous. Circuit conductors shall be sized to carry not less than the larger of 690.8(B)(1) or (2). (1) One hundred and twenty-five percent of the maximum currents calculated in 690.8(A) before the application of adjustment and correction factors. Exception: Circuits containing an assembly, together with its overcurrent device(s), that is listed for continuous operation at 100 percent of its rating shall be permitted to be used at 100 percent of its rating. Just to be clear, it is only the assembly that can be used at 100 percent of its rating. (Isc*number of strings*1.25) The conductors in the circuit still have to be sized for continuous operation (Isc*number of strings*1.25*1.25). I ask because a vendor with a 100% circuit breaker re-combiner states in their cut sheet that use of the device allow smaller home run cable sizes from the string combiner to the inverter. Is anyone aware of a means by which this claim can be substantiated? Thanks, Mark Frye Berkeley Solar Electric Systems ___ 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
Re: [RE-wrenches] Assembly Protects Conductors?
HI Mark, Ive been having this discussion with some others. 690.9B I think means that the 2nd 125% is for breaker derating. I have looked and can't find anywhere in the code about conductors being derated for continuous use. Other deratings yes, temp, conduit etc etc. But there are many others out there way way better on code than me, and so correct me please. IMHO, I think this 2nd 25% has been misinterpreted to mean conductor instead of breaker derating. jay peltz power On Aug 23, 2014, at 8:41 AM, Mark Frye wrote: Ray, I can't follow you all the way down that path. Is an insulated wire conductor permitted to be use at 100% of it's rating under continuous operation? No. The ampacity is reduced and the conductor must be up-sized. Hence, for a defined load (Isc * 1.25), under continious operation, the conductor must be upsized to match (defined load * 1.25). I don't see how this can be changed by simply changing the nature of the OCP. I think the point of this exception is to allow cost savings by allow assemblies and OCP devices with lower ratings. The exception does not apply to every element of the circuit (the conductors) but only to the 100% rated assemblies and OCP themselves. What am I missing? Thanks, Mark On 8/22/2014 6:14 PM, Ray Walters wrote: Most combiner boxes, DC rated breakers, and DC rated fuses and fuse holders we use today, qualify as assemblies for the 100% exception (Outback, Midnite, etc.) so you only have to size the OCP by 125% of short circuit current rating for edge of cloud effects. Since the conductor is sized based on the overcurrent protection, you do not need to size it to 156% of the short circuit current rating, if you take advantage of 100% duty rated breakers and combiners. Also, recombiners are still basically combiner boxes, and so all the same rules apply. The additional 125% is only for breakers that are rated at 80% (most AC breakers for example) . For DC, the only time you would size for the full 156% would be if you were using something like an old QOU breaker, and those aren't rated for high enough voltage for today's arrays anyway. I'm not aware of any other readily available DC rated breaker that is NOT 100% duty rated. Some RK5 fuse assemblies may also not be 100% rated. (Wrench Colleagues please correct me on this) Basically unless you are using surplus equipment from the stone age, (no offense to my fellow stone age wrenches) you only need to oversize the conductors by 125%. By the time you apply all the other applicable deratings for conduit fill, terminals rated at 75 C, and direct sunlight on roofs (table 310.15B3c) and consider voltage drop, you really don't need to keep oversizing. R.Ray Walters CTO, Solarray, Inc Nabcep Certified PV Installer, Licensed Master Electrician Solar Design Engineer 303 505-8760 On 8/22/2014 2:34 PM, ma...@berkeleysolar.com wrote: Folks, In looking at a circuit breaker based re-combiner for the first time, I am now pondering the meaning of the Exception below: NEC 2014 690.8 (B) Conductor Ampacity. PV system currents shall be considered to be continuous. Circuit conductors shall be sized to carry not less than the larger of 690.8(B)(1) or (2). (1) One hundred and twenty-five percent of the maximum currents calculated in 690.8(A) before the application of adjustment and correction factors. Exception: Circuits containing an assembly, together with its overcurrent device(s), that is listed for continuous operation at 100 percent of its rating shall be permitted to be used at 100 percent of its rating. Just to be clear, it is only the assembly that can be used at 100 percent of its rating. (Isc*number of strings*1.25) The conductors in the circuit still have to be sized for continuous operation (Isc*number of strings*1.25*1.25). I ask because a vendor with a 100% circuit breaker re-combiner states in their cut sheet that use of the device allow smaller home run cable sizes from the string combiner to the inverter. Is anyone aware of a means by which this claim can be substantiated? Thanks, Mark Frye Berkeley Solar Electric Systems ___ 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:
Re: [RE-wrenches] Assembly Protects Conductors?
The 100% exception is listed in 2 places: 690.8(B)(1) which sizes the conductor, and 690.9(B) which sizes the OCD. Article 210 doesn't apply, as that is for branch circuits, not PV source circuits. 690.8 basically walks you through conductor sizing. 690.8(B) requires 2 calculations one for B(1) which is simply Asc x 125% ( 690.8(A)(1) the edge of cloud effect), and is exempted from any additional derating if using the 100% rated assemblies. 690.9(B)(2) then takes Asc x 125% as well, and then applies all the previously mentioned adjustments and correction factors. Which ever is larger is what you are required to use. The 100% exemption basically means that 690.9(B)(2) will prevail, and you may end up with a bit less than the additional 125% (or not) Basically, the days of multiplying by 156% are mostly over with today's combiner boxes. However, properly applying all the corrections and deratings on a roof is a different story, that has been covered by others more informed than I. Check SolarPro magazine, and 310.15. Later we can get into the debate of when to apply table 310.15(B)(17) ampacity ratings in free air.. Does it apply to array conductors before they transition into conduit? Does it apply (as some manufacturers claim) inside of enclosures, or for conductors run through less than24 of raceway? Stay tuned, I'm still trying to figure that one out. Does someone else want to jump in here? R.Ray Walters CTO, Solarray, Inc Nabcep Certified PV Installer, Licensed Master Electrician Solar Design Engineer 303 505-8760 On 8/23/2014 9:41 AM, Mark Frye wrote: Ray, I can't follow you all the way down that path. Is an insulated wire conductor permitted to be use at 100% of it's rating under continuous operation? No. The ampacity is reduced and the conductor must be up-sized. Hence, for a defined load (Isc * 1.25), under continious operation, the conductor must be upsized to match (defined load * 1.25). I don't see how this can be changed by simply changing the nature of the OCP. I think the point of this exception is to allow cost savings by allow assemblies and OCP devices with lower ratings. The exception does not apply to every element of the circuit (the conductors) but only to the 100% rated assemblies and OCP themselves. What am I missing? Thanks, Mark On 8/22/2014 6:14 PM, Ray Walters wrote: Most combiner boxes, DC rated breakers, and DC rated fuses and fuse holders we use today, qualify as assemblies for the 100% exception (Outback, Midnite, etc.) so you only have to size the OCP by 125% of short circuit current rating for edge of cloud effects. Since the conductor is sized based on the overcurrent protection, you do not need to size it to 156% of the short circuit current rating, if you take advantage of 100% duty rated breakers and combiners. Also, recombiners are still basically combiner boxes, and so all the same rules apply. The additional 125% is only for breakers that are rated at 80% (most AC breakers for example) . For DC, the only time you would size for the full 156% would be if you were using something like an old QOU breaker, and those aren't rated for high enough voltage for today's arrays anyway. I'm not aware of any other readily available DC rated breaker that is NOT 100% duty rated. Some RK5 fuse assemblies may also not be 100% rated. (Wrench Colleagues please correct me on this) Basically unless you are using surplus equipment from the stone age, (no offense to my fellow stone age wrenches) you only need to oversize the conductors by 125%. By the time you apply all the other applicable deratings for conduit fill, terminals rated at 75 C, and direct sunlight on roofs (table 310.15B3c) and consider voltage drop, you really don't need to keep oversizing. R.Ray Walters CTO, Solarray, Inc Nabcep Certified PV Installer, Licensed Master Electrician Solar Design Engineer 303 505-8760 On 8/22/2014 2:34 PM, ma...@berkeleysolar.com wrote: Folks, In looking at a circuit breaker based re-combiner for the first time, I am now pondering the meaning of the Exception below: NEC 2014 690.8 (B) Conductor Ampacity. PV system currents shall be considered to be continuous. Circuit conductors shall be sized to carry not less than the larger of 690.8(B)(1) or (2). (1) One hundred and twenty-five percent of the maximum currents calculated in 690.8(A) before the application of adjustment and correction factors. Exception: Circuits containing an assembly, together with its overcurrent device(s), that is listed for continuous operation at 100 percent of its rating shall be permitted to be used at 100 percent of its rating. Just to be clear, it is only the assembly that can be used at 100 percent of its rating. (Isc*number of strings*1.25) The conductors in the circuit still have to be sized for continuous operation (Isc*number of strings*1.25*1.25). I ask because a vendor with a 100% circuit breaker re-combiner
Re: [RE-wrenches] Assembly Protects Conductors?
Wow. OK Ray. This issue of 100% rated under continious use is interesting. Thanks for helping me get my head around it. The exception in 210.19 is certainly explicit. Too bad, for this one man, the exception in 690.8 is less so. Mark On 8/23/2014 10:35 AM, Ray Walters wrote: The 100% exception is listed in 2 places: 690.8(B)(1) which sizes the conductor, and 690.9(B) which sizes the OCD. Article 210 doesn't apply, as that is for branch circuits, not PV source circuits. 690.8 basically walks you through conductor sizing. 690.8(B) requires 2 calculations one for B(1) which is simply Asc x 125% ( 690.8(A)(1) the edge of cloud effect), and is exempted from any additional derating if using the 100% rated assemblies. 690.9(B)(2) then takes Asc x 125% as well, and then applies all the previously mentioned adjustments and correction factors. Which ever is larger is what you are required to use. The 100% exemption basically means that 690.9(B)(2) will prevail, and you may end up with a bit less than the additional 125% (or not) Basically, the days of multiplying by 156% are mostly over with today's combiner boxes. However, properly applying all the corrections and deratings on a roof is a different story, that has been covered by others more informed than I. Check SolarPro magazine, and 310.15. Later we can get into the debate of when to apply table 310.15(B)(17) ampacity ratings in free air.. Does it apply to array conductors before they transition into conduit? Does it apply (as some manufacturers claim) inside of enclosures, or for conductors run through less than24 of raceway? Stay tuned, I'm still trying to figure that one out. Does someone else want to jump in here? R.Ray Walters CTO, Solarray, Inc Nabcep Certified PV Installer, Licensed Master Electrician Solar Design Engineer 303 505-8760 On 8/23/2014 9:41 AM, Mark Frye wrote: Ray, I can't follow you all the way down that path. Is an insulated wire conductor permitted to be use at 100% of it's rating under continuous operation? No. The ampacity is reduced and the conductor must be up-sized. Hence, for a defined load (Isc * 1.25), under continious operation, the conductor must be upsized to match (defined load * 1.25). I don't see how this can be changed by simply changing the nature of the OCP. I think the point of this exception is to allow cost savings by allow assemblies and OCP devices with lower ratings. The exception does not apply to every element of the circuit (the conductors) but only to the 100% rated assemblies and OCP themselves. What am I missing? Thanks, Mark On 8/22/2014 6:14 PM, Ray Walters wrote: Most combiner boxes, DC rated breakers, and DC rated fuses and fuse holders we use today, qualify as assemblies for the 100% exception (Outback, Midnite, etc.) so you only have to size the OCP by 125% of short circuit current rating for edge of cloud effects. Since the conductor is sized based on the overcurrent protection, you do not need to size it to 156% of the short circuit current rating, if you take advantage of 100% duty rated breakers and combiners. Also, recombiners are still basically combiner boxes, and so all the same rules apply. The additional 125% is only for breakers that are rated at 80% (most AC breakers for example) . For DC, the only time you would size for the full 156% would be if you were using something like an old QOU breaker, and those aren't rated for high enough voltage for today's arrays anyway. I'm not aware of any other readily available DC rated breaker that is NOT 100% duty rated. Some RK5 fuse assemblies may also not be 100% rated. (Wrench Colleagues please correct me on this) Basically unless you are using surplus equipment from the stone age, (no offense to my fellow stone age wrenches) you only need to oversize the conductors by 125%. By the time you apply all the other applicable deratings for conduit fill, terminals rated at 75 C, and direct sunlight on roofs (table 310.15B3c) and consider voltage drop, you really don't need to keep oversizing. R.Ray Walters CTO, Solarray, Inc Nabcep Certified PV Installer, Licensed Master Electrician Solar Design Engineer 303 505-8760 On 8/22/2014 2:34 PM, ma...@berkeleysolar.com wrote: Folks, In looking at a circuit breaker based re-combiner for the first time, I am now pondering the meaning of the Exception below: NEC 2014 690.8 (B) Conductor Ampacity. PV system currents shall be considered to be continuous. Circuit conductors shall be sized to carry not less than the larger of 690.8(B)(1) or (2). (1) One hundred and twenty-five percent of the maximum currents calculated in 690.8(A) before the application of adjustment and correction factors. Exception: Circuits containing an assembly, together with its overcurrent device(s), that is listed for continuous operation at 100 percent of its rating shall be permitted to be used at 100 percent of its rating. Just to be
[RE-wrenches] Assembly Protects Conductors?
Folks, In looking at a circuit breaker based re-combiner for the first time, I am now pondering the meaning of the Exception below: NEC 2014 690.8 (B) Conductor Ampacity. PV system currents shall be considered to be continuous. Circuit conductors shall be sized to carry not less than the larger of 690.8(B)(1) or (2). (1) One hundred and twenty-five percent of the maximum currents calculated in 690.8(A) before the application of adjustment and correction factors. Exception: Circuits containing an assembly, together with its overcurrent device(s), that is listed for continuous operation at 100 percent of its rating shall be permitted to be used at 100 percent of its rating. Just to be clear, it is only the assembly that can be used at 100 percent of its rating. (Isc*number of strings*1.25) The conductors in the circuit still have to be sized for continuous operation (Isc*number of strings*1.25*1.25). I ask because a vendor with a 100% circuit breaker re-combiner states in their cut sheet that use of the device allow smaller home run cable sizes from the string combiner to the inverter. Is anyone aware of a means by which this claim can be substantiated? Thanks, Mark Frye Berkeley Solar Electric Systems ___ 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
Re: [RE-wrenches] Assembly Protects Conductors?
Thanks Chris, It's one of those great things about the solar industry that there is always more stuff going on than one man can keep track of: http://www.bentek.com/solar-products/recombiners/circuit-breaker/ Mark, The term recombiner to me is an electrical panel used on the AC output of multiple inverters to combine their electrical outputs. That is different to a combiner which connects solar strings through fuses to a busbar for connection to the inverter using one conductor pair. In grid tied systems, you will probably not find breakers that can be used in combiners as the 600V or 1,000v max DC voltage is above what most breakers can operate at, hence the use of touch safe fuses. I don't think the NEC recognizes recombiners panels as existing at all. Standard rules require the breakers to be 125% rated as the output is continuous. ___ 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
Re: [RE-wrenches] Assembly Protects Conductors?
Most combiner boxes, DC rated breakers, and DC rated fuses and fuse holders we use today, qualify as assemblies for the 100% exception (Outback, Midnite, etc.) so you only have to size the OCP by 125% of short circuit current rating for edge of cloud effects. Since the conductor is sized based on the overcurrent protection, you do not need to size it to 156% of the short circuit current rating, if you take advantage of 100% duty rated breakers and combiners. Also, recombiners are still basically combiner boxes, and so all the same rules apply. The additional 125% is only for breakers that are rated at 80% (most AC breakers for example) . For DC, the only time you would size for the full 156% would be if you were using something like an old QOU breaker, and those aren't rated for high enough voltage for today's arrays anyway. I'm not aware of any other readily available DC rated breaker that is NOT 100% duty rated. Some RK5 fuse assemblies may also not be 100% rated. (Wrench Colleagues please correct me on this) Basically unless you are using surplus equipment from the stone age, (no offense to my fellow stone age wrenches) you only need to oversize the conductors by 125%. By the time you apply all the other applicable deratings for conduit fill, terminals rated at 75 C, and direct sunlight on roofs (table 310.15B3c) and consider voltage drop, you really don't need to keep oversizing. R.Ray Walters CTO, Solarray, Inc Nabcep Certified PV Installer, Licensed Master Electrician Solar Design Engineer 303 505-8760 On 8/22/2014 2:34 PM, ma...@berkeleysolar.com wrote: Folks, In looking at a circuit breaker based re-combiner for the first time, I am now pondering the meaning of the Exception below: NEC 2014 690.8 (B) Conductor Ampacity. PV system currents shall be considered to be continuous. Circuit conductors shall be sized to carry not less than the larger of 690.8(B)(1) or (2). (1) One hundred and twenty-five percent of the maximum currents calculated in 690.8(A) before the application of adjustment and correction factors. Exception: Circuits containing an assembly, together with its overcurrent device(s), that is listed for continuous operation at 100 percent of its rating shall be permitted to be used at 100 percent of its rating. Just to be clear, it is only the assembly that can be used at 100 percent of its rating. (Isc*number of strings*1.25) The conductors in the circuit still have to be sized for continuous operation (Isc*number of strings*1.25*1.25). I ask because a vendor with a 100% circuit breaker re-combiner states in their cut sheet that use of the device allow smaller home run cable sizes from the string combiner to the inverter. Is anyone aware of a means by which this claim can be substantiated? Thanks, Mark Frye Berkeley Solar Electric Systems ___ 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
Re: [RE-wrenches] Assembly Protects Conductors?
To at least partially answer Ray's question about Class-R fuses: Square-D Heavy Duty fused disconnects, commonly used as DC discos for PV arrays and which use Class-R fuses, are only rated for 80% duty. The non-fused HD discos are 100% rated in PV systems. I'm not sure if that is because of the fuse rating or the fuse holder rating though. Brian Teitelbaum AEE Solar -Original Message- From: RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Ray Walters Sent: Friday, August 22, 2014 6:14 PM To: RE-wrenches Subject: Re: [RE-wrenches] Assembly Protects Conductors? Most combiner boxes, DC rated breakers, and DC rated fuses and fuse holders we use today, qualify as assemblies for the 100% exception (Outback, Midnite, etc.) so you only have to size the OCP by 125% of short circuit current rating for edge of cloud effects. Since the conductor is sized based on the overcurrent protection, you do not need to size it to 156% of the short circuit current rating, if you take advantage of 100% duty rated breakers and combiners. Also, recombiners are still basically combiner boxes, and so all the same rules apply. The additional 125% is only for breakers that are rated at 80% (most AC breakers for example) . For DC, the only time you would size for the full 156% would be if you were using something like an old QOU breaker, and those aren't rated for high enough voltage for today's arrays anyway. I'm not aware of any other readily available DC rated breaker that is NOT 100% duty rated. Some RK5 fuse assemblies may also not be 100% rated. (Wrench Colleagues please correct me on this) Basically unless you are using surplus equipment from the stone age, (no offense to my fellow stone age wrenches) you only need to oversize the conductors by 125%. By the time you apply all the other applicable deratings for conduit fill, terminals rated at 75 C, and direct sunlight on roofs (table 310.15B3c) and consider voltage drop, you really don't need to keep oversizing. R.Ray Walters CTO, Solarray, Inc Nabcep Certified PV Installer, Licensed Master Electrician Solar Design Engineer 303 505-8760 On 8/22/2014 2:34 PM, ma...@berkeleysolar.com wrote: Folks, In looking at a circuit breaker based re-combiner for the first time, I am now pondering the meaning of the Exception below: NEC 2014 690.8 (B) Conductor Ampacity. PV system currents shall be considered to be continuous. Circuit conductors shall be sized to carry not less than the larger of 690.8(B)(1) or (2). (1) One hundred and twenty-five percent of the maximum currents calculated in 690.8(A) before the application of adjustment and correction factors. Exception: Circuits containing an assembly, together with its overcurrent device(s), that is listed for continuous operation at 100 percent of its rating shall be permitted to be used at 100 percent of its rating. Just to be clear, it is only the assembly that can be used at 100 percent of its rating. (Isc*number of strings*1.25) The conductors in the circuit still have to be sized for continuous operation (Isc*number of strings*1.25*1.25). I ask because a vendor with a 100% circuit breaker re-combiner states in their cut sheet that use of the device allow smaller home run cable sizes from the string combiner to the inverter. Is anyone aware of a means by which this claim can be substantiated? Thanks, Mark Frye Berkeley Solar Electric Systems ___ 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.htm l 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
