NEC article 210 writes about “branch circuits” up to 600V. I didn’t see a limit on current, so we’ve always applied it to OCP and ampacity for all conductors on circuits where the current is expected to be “continuous”, as defined in the code. ( we go up to 2000A on a 575V circuit on a custom transformer, dedicated circuit)
>From chapter II: "Where a branch circuit supplies continuous loads or any >combination of continuous and non-continuous loads, the minimum branch-circuit >conductor size shall have an allowable ampacity not less than the >non-continuous load plus 125 percent of the continuous load." It's easy for our equipment where it is always supplied by a dedicated "branch circuit" (often a dedicated transformer) and current is continuous by definition. (> 3hrs) Strictly speaking, it's a 125% rule, not an 80% rule Ralph McDiarmid Product Compliance Engineering Solar Business Schneider Electric From: Kunde, Brian [mailto:brian_ku...@lecotc.com] Sent: Wednesday, October 11, 2017 12:02 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] NEMA 5-20P with IEC 60320 C13 One last quick question, if I may, while we are all up on the NEC. Just to confirm, the 80% rule only applies to 15A, 20A, and 30A branch circuits. 40A and 50A branch circuits do not have the 80% rule, even in a multiple-outlet configuration? I know these larger circuits are generally dedicated circuits, but that is how the rules read in the NEC 210.23(C). Unless I’m missing something. Thanks bunches. The Other Brian From: John Woodgate [mailto:j...@woodjohn.uk] Sent: Wednesday, October 11, 2017 2:57 PM To: Kunde, Brian; mailto:EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] NEMA 5-20P with IEC 60320 C13 Yes, of course quite a thin conductor will carry enough current to operate the protection, because it doesn't have time to get seriously hot. John Woodgate OOO-Own Opinions Only J M Woodgate and Associates http://www.woodjohn.uk Rayleigh, Essex UK On 2017-10-11 19:35, Kunde, Brian wrote: I know I started this thread, so I'm going to circuit back via another direction. The NEC allows a product with an 18 awg power cord (rated 10 amps), a 15 amp plug, and C13 IEC connector (15 amp) to be plugged into a 15 amp branch circuit. OH, you can also plug it into a 20 amp branch circuit because the receptacles will accept a 15 amp plug. So what protects the freakishly small 18 awg power cord from bursting into flames in an overload condition? Must be the OverCurrent Protection device in the product itself. Correct? So back to original questions, can I use a power cord with a 20 amp plug (NEMA 5-20P), 12 awg wire, and 15 amp IEC C13 connector on a product that draws 15 amps and has a double pole 15 amp OCPD? With the same logic above, the OCP device is protecting the power cord. Would you allow this? Then again, your you allow a 18awg power cord to be used on a 15 amp circuit? The NEC says it is ok. Thanks, The Other Brian -----Original Message----- From: Nyffenegger, Dave [mailto:dave.nyffeneg...@bhemail.com] Sent: Wednesday, October 11, 2017 1:30 PM To: mailto:EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] NEMA 5-20P with IEC 60320 C13 Had a condo with a smallish through-the-wall A/C unit with NEMA 5-15P plug. In the room on one side of the unit was a dedicated 20A single outlet for the A/C unit. In the room on the other side easily within reach of the cord was a standard duplex outlet on the room circuit. Guess which one the A/C was plugged into? -Dave -----Original Message----- From: Pete Perkins [mailto:00000061f3f32d0c-dmarc-requ...@ieee.org] Sent: Wednesday, October 11, 2017 1:04 PM To: mailto:EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] NEMA 5-20P with IEC 60320 C13 Ralph, Ted et al, Dunno how many times I have had this conversation with the project engineer who wants to use the full rated current from the duplex outlet (and not leave any for the other user who plugs into that outlet - which gives rise to the 80% rule) - except if they want to specify in the installation that the user must have an expensive electrician install a special dedicated outlet (only one plug available to the user on that CB controlled circuit); which gives rise to the marketing folks nixing the idea. :>) Carry on! As you were doing... :>) br, Pete Peter E Perkins, PE Principal Product Safety & Regulatory Affairs Consultant PO Box 23427 Tigard, ORe 97281-3427 503/452-1201 mailto:p.perk...@ieee.org -----Original Message----- From: Ralph McDiarmid [mailto:ralph.mcdiar...@schneider-electric.com] Sent: Wednesday, October 11, 2017 9:05 AM To: mailto:EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] NEMA 5-20P with IEC 60320 C13 Sounds like an example of the 125% rule for continuous (>3hr) current. (20/16) Ralph McDiarmid Product Compliance Engineering Solar Business Schneider Electric From: Ted Eckert [mailto:000007cf6ebeab9d-dmarc-requ...@ieee.org] Sent: Wednesday, October 11, 2017 5:50 AM To: mailto:EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] NEMA 5-20P with IEC 60320 C13 NFPA 70 allows 20 A connectors to be used at 20 A under a number of circumstances. The derating issue only applies in certain cases. Just changing the rating doesn’t resolve the issue as it would eliminate already accepted safe use of the connectors at their full rating. Ted Eckert Microsoft Corporation The opinions expressed are my own and do not necessarily reflect those of my employer. From: John Woodgate [mailto:j...@woodjohn.uk] Sent: Tuesday, October 10, 2017 11:21 PM To: Ted Eckert mailto:ted.eck...@microsoft.com; mailto:EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] NEMA 5-20P with IEC 60320 C13 Yes, it could be difficult to change to respecting the rated values, so how about respecting the de-rated values instead? Instead of saying that you can only use this 20 A connector up to 16 A, call it a 16 A connector? John Woodgate OOO-Own Opinions Only J M Woodgate and Associates https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.woodjohn.uk&data=02%7C01%7CTed.Eckert%40MICROSOFT.COM%7C6f5a4a13ae97469548f108d510703247%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636432996434092831&sdata=vbIPUaUZRYojTmRGRu9LrQO4Emqy7f8wN1OY8mY%2BQFg%3D&reserved=0 Rayleigh, Essex UK On 2017-10-10 21:57, Ted Eckert wrote: The various clauses of NFPA 70 are reviewed, challenged, debated, argued and rewritten. I don’t think the clause in question remains because nobody has challenged it. Part of the issue is that the electrical infrastructure in the U.S. has been developed around this rule. If affects circuit breaker trip curves, conduit fill, wire sizes and rating and many other aspects of a building’s electrical system. If the rule were changed, would there be problems switching over? Would you have overheating in older structures where circuit breakers were replaced without updating wiring? Wold there be other effects of mixing 80% and 100% rated components? How many U.S. national standards would need to be updated? It is a poor analogy, but think about switching sides that you drive on the road. Sweden switched on September 3, 1967. Street signs, traffic signals and road markings all had to be changed. Headlights had to be adjusted or re-aimed. For quite a while, there was a mix of left-hand and right-hand drive cars. It was a massive undertaking for a country with fewer people than either London or New York City. Changing the way branch circuits are rated in the U.S. could be done, but it would be an extremely complicated undertaking. The risks of a mismatch of circuits, circuit protection and loads would be significant for a long time. I suspect that by the time the technology evolved to the point where the requirement could be eliminated, it was too late and eliminating it would result in too much expense and rework. Ted Eckert Microsoft Corporation The opinions expressed are my own and do not necessarily reflect those of my employer. From: John Woodgate [mailto:j...@woodjohn.uk] Sent: Tuesday, October 10, 2017 12:49 PM To: mailto:EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] NEMA 5-20P with IEC 60320 C13 Well, yes, because the IEC tends to believe that rated values are realistic and do not need to be adjusted downwards. I suspect that at some point in the distant past (maybe even nearly 100 years ago), some connectors in wide use were found to overheat at rated current, so the 'derating rule' was brought in, and no-one has challenged it since. John Woodgate OOO-Own Opinions Only J M Woodgate and Associates https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.woodjohn.uk&data=02%7C01%7Cted.eckert%40microsoft.com%7Cb9a5abba70d24e2f093e08d51018031b%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636432617679408094&sdata=jNpj%2FFhCHx9ir37o7Xf5GxovOe2h0nU9FIZnbo5mItE%3D&reserved=0 Rayleigh, Essex UK On 2017-10-10 20:12, Ralph McDiarmid wrote: The NEC (NFPA 70) talks about “continuous currents” and when to apply the all-too-familiar 125% rule. Canadian Electric Code (CSA part I) has same requirement. The IEC seems to have avoided it. Ralph McDiarmid Product Compliance Engineering Solar Business Schneider Electric D 604-422-2622 From: Kunde, Brian [mailto:brian_ku...@lecotc.com] Sent: Monday, October 09, 2017 8:31 AM To: mailto:EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] NEMA 5-20P with IEC 60320 C13 It is my understanding that according to the US National Electric Code, 15 amp receptacle are derated to 12 amps max., and 20 amp receptacles are derated to 16 amps. IEC 60320 C13 connectors are rated 15 amps in North America. Do I derate them as well or can I draw 15 amps continuous from the C13 connector? So here is the big question: If I have a power cord with a NEMA-5-20P at one end, IEC 60320 C13 at the other end, and 14awg cordage (rated 18A), can I use/ship this power cord with a product rated 15 amps? Thanks to all. The Other Brian ________________________________________ LECO Corporation Notice: This communication may contain confidential information intended for the named recipient(s) only. 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