Jim, Your not going to find a single statement that says all breakers must have interrupt ratings at least 5000 A. The requirement is embedded in the NRTL Listing of the circuit breaker. "Supps" are not Listed.
You will find the following hints: 110.2 "Approval - The conductors and equipment required or permitted by this Code shall be accepted only if approved". By this, you can only use Listed circuit breakers. Here is the link to UL's General Guide Info for Molded-Cased Circuit breakers and circuit-breaker enclosures. Note that there is a marking requirement for breakers with an interrupt rating greater than 5000 A, because 5000 A is the minimum rating in accordance with UL 489: http://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/showpage.html?name =DIVQ.GuideInfo&ccnshorttitle=Circuit+Breakers,+Molded-case+and+Circuit+Brea ker+Enclosures&objid=1074081597&cfgid=1073741824&version=versionless&parent_ id=1073985604&sequence=1 You might want to refer to 110.9 "Interrupt rating", and 240.83(C) of the 2005 NEC Handbook (because the blue-print has useful information) concerning interrupt rating markings on circuit breakers. Now, concerning supplementary protectors, remember 110.2 above? There is no Listing category for supplementary protectors! They are UL Recognized, which means that they can only be used as internal protection for Listed appliances. They do not generally have 5000 A interrupt capability. Here is the link to the General Guide for supplementary protectors: http://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/showpage.html?name =QVNU2.GuideInfo&ccnshorttitle=Protectors,+Supplementary+-+Component&objid=1 073793222&cfgid=1073741824&version=versionless&parent_id=1073793221&sequence =1 The guide says that supplementary protectors are not intended to provide branch circuit overcurrent protection required by ANSI/NFPA 70, "National Electrical Code". Hope this helps, Don Gies, N.C.E Senior Product Compliance Engineer Lucent Technologies Holmdel, NJ 07733 USA From: Jim Eichner [mailto:[email protected]] Sent: Monday, September 19, 2005 8:07 PM To: [email protected] Subject: Protectors vs breakers in the NEC I'm sure it's in there...somewhere. I'm looking for where the NEC (2005 please) says that the overcurrent protection provided for branch circuits has to be a circuit breaker with an interrupt rating of at least X (I believe it's 5000A), as opposed to a supplemental protector. The closest thing I can find is... 110.9 Interrupting Rating. Equipment intended to interrupt current at fault levels shall have an interrupting rating sufficient for the nominal circuit voltage and the current that is available at the line terminals of the equipment. This doesn't really say it. It suggests that if I could go buy a supplemental protector rated for say 500A interrupt and if I could convince the electrical inspector that at the location where it will be installed (say in a sub-panel at the end of a long run of No. 14AWG wire) that's all the fault current available, then that would be ok?! I thought they had to be "real" circuit breakers AND they had to have appropriate interrupt ratings. Yes? No? Thanks, Jim Eichner, P.Eng. Compliance Engineering Manager Xantrex Technology Inc. e-mail: [email protected] web: www.xantrex.com Confidentiality Notice: This email message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. - 2005 IEEE Symposium on Product Safety Engineering 3-4 October Schaumburg, IL http://www.ieee-pses.org/symposium This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc - 2005 IEEE Symposium on Product Safety Engineering 3-4 October Schaumburg, IL http://www.ieee-pses.org/symposium This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
