Nec 2011
Páginas: 43 (10516 palabras)
Publicado: 17 de marzo de 2012
Top Ten Changes
to the
by: Matt Buecker electrical-design-tutor.com
1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
Grounding Receptacles New/Updated Definitions GFCI Protection Arc Fault Circuit Interrupters Environmental Air / Plenum Conductors Means of Disconnect Small Wind Electric Systems Plug-In Hybrid Electric Vehicles
Page 1 of 30
The National Electrical Code (NEC) is updated every threeyears. Otherwise known as NFPA Chapter 70, the NEC has been published since 1897 and is responsible for continuously improving the safety of those who install electrical devices and the quality of work for those that use electricity (essentially, everyone). NEC 2011, the latest edition, continues this tradition. This article is meant for electrical professionals, new and experienced alike, who arepreparing for the inevitable transition away from NEC 2008 by the electrical industry. Using new NEC 2011 excerpts, my goal is to focus on the main areas of change and provide commentary for the changes involved.. The key to reading this article is to have your NEC 2011 Code book next to you. I have no interest in plagiarizing the entire Code so I simply have re-printed the areas of the Codewhere the changes occur so that you can flip to that page and see for yourself the entire context of the changes. Reading Key: = Areas of the code that have been revised or are new from NEC 2008. My take:... = My analysis or interpretation of what the change is and/or why it was added. (No Change from NEC 2008) = This note is entered for reference only as the exact section specified is the same in the2011 edition as it is in the 2008 edition. It does not literally say “No Change from NEC 2008”.
Take all the time you need to read this article as it contains the vast majority of the changes to NEC 2011 (the others are minor grammatical adjustments). Although most AHJ's (authority having jurisdiction) have not adopted the NEC 2011 yet, you will be better prepared for it after reading thisarticle.
Page 2 of 30
My take: Article 250 contains significant changes from the NEC 2008, with a heavy emphasis on grounding in separately derived systems. The Code tries to clarify throughout Artcile 250 that grounding and bonding are directly related and are not two different concepts. And with the numerous additions to section 690.47, the NEC 2011 is providing guidance for grounding onboth the ac and dc side of the inverter for Solar PV systems. 250.2 Definitions Bonding Jumper, Supply-Side. A conductor installed on the supply side of a service or within a service equipment enclosure(s), or for a separately derived system, that ensures the required electrical conductivity between metal parts required to be electrically connected. 250.30 Grounding Separately DerivedAlternating-Current Systems In addition to complying with 250.30(A) for grounded systems, or as provided in 250.30(B) for ungrounded systems, separately derived systems shall comply with 250.20, 250.21, 250.22, and 250.26.
Informational Note No. 1: An alternate ac power source, such as an on-site generator, is not a separately derived system if the grounded conductor is solidly interconnected to aservice-supplied system grounded conductor. An example of such a situation is where alternate source transfer equipment does not include a switching action in the grounded conductor and allows it to remain solidly connected to the service-supplied grounded conductor when the alternate source is operational and supply the load served. Informational Note No. 2: See 445.13 for the minimum size of conductors thatcarry fault current.
1. Grounding
My take: The notes are added to clarify the requirements of grounding for separately derived systems. There's not much new except that the Code is clarifying code sections that apply to separately derived systems and that a solidly connected neutral means a generator is not a separately derived system. (A) Grounded Systems. A separately derived ac system...
to the
by: Matt Buecker electrical-design-tutor.com
1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
Grounding Receptacles New/Updated Definitions GFCI Protection Arc Fault Circuit Interrupters Environmental Air / Plenum Conductors Means of Disconnect Small Wind Electric Systems Plug-In Hybrid Electric Vehicles
Page 1 of 30
The National Electrical Code (NEC) is updated every threeyears. Otherwise known as NFPA Chapter 70, the NEC has been published since 1897 and is responsible for continuously improving the safety of those who install electrical devices and the quality of work for those that use electricity (essentially, everyone). NEC 2011, the latest edition, continues this tradition. This article is meant for electrical professionals, new and experienced alike, who arepreparing for the inevitable transition away from NEC 2008 by the electrical industry. Using new NEC 2011 excerpts, my goal is to focus on the main areas of change and provide commentary for the changes involved.. The key to reading this article is to have your NEC 2011 Code book next to you. I have no interest in plagiarizing the entire Code so I simply have re-printed the areas of the Codewhere the changes occur so that you can flip to that page and see for yourself the entire context of the changes. Reading Key: = Areas of the code that have been revised or are new from NEC 2008. My take:... = My analysis or interpretation of what the change is and/or why it was added. (No Change from NEC 2008) = This note is entered for reference only as the exact section specified is the same in the2011 edition as it is in the 2008 edition. It does not literally say “No Change from NEC 2008”.
Take all the time you need to read this article as it contains the vast majority of the changes to NEC 2011 (the others are minor grammatical adjustments). Although most AHJ's (authority having jurisdiction) have not adopted the NEC 2011 yet, you will be better prepared for it after reading thisarticle.
Page 2 of 30
My take: Article 250 contains significant changes from the NEC 2008, with a heavy emphasis on grounding in separately derived systems. The Code tries to clarify throughout Artcile 250 that grounding and bonding are directly related and are not two different concepts. And with the numerous additions to section 690.47, the NEC 2011 is providing guidance for grounding onboth the ac and dc side of the inverter for Solar PV systems. 250.2 Definitions Bonding Jumper, Supply-Side. A conductor installed on the supply side of a service or within a service equipment enclosure(s), or for a separately derived system, that ensures the required electrical conductivity between metal parts required to be electrically connected. 250.30 Grounding Separately DerivedAlternating-Current Systems In addition to complying with 250.30(A) for grounded systems, or as provided in 250.30(B) for ungrounded systems, separately derived systems shall comply with 250.20, 250.21, 250.22, and 250.26.
Informational Note No. 1: An alternate ac power source, such as an on-site generator, is not a separately derived system if the grounded conductor is solidly interconnected to aservice-supplied system grounded conductor. An example of such a situation is where alternate source transfer equipment does not include a switching action in the grounded conductor and allows it to remain solidly connected to the service-supplied grounded conductor when the alternate source is operational and supply the load served. Informational Note No. 2: See 445.13 for the minimum size of conductors thatcarry fault current.
1. Grounding
My take: The notes are added to clarify the requirements of grounding for separately derived systems. There's not much new except that the Code is clarifying code sections that apply to separately derived systems and that a solidly connected neutral means a generator is not a separately derived system. (A) Grounded Systems. A separately derived ac system...
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