Though the NEC doesn't have a specific definition for "Continuous Input Current", as you mentioned before, it does define "Continuous Load" as "A load where the maximum current is expected to continue for 3 hours or more."
The NEC also uses the terms, "Noncontinuous Load" and "Steady State" yet they do not define these terms specifically. I assume they must feel these terms are self explanatory and didn't require a specific definition. On the IEC/EN/UL 61010-1 standard (safety of ISM equipment) that we primarily deal with, it simply states that on the equipment you must include the "maximum RATED power" or "maximum RATED input current", yet the standard does not explain how this is determined. It does say that compliance is verified by measurement of power or input current but to exclude inrush and transients, and not made "until the current has stabilized". This is where we unofficially get the term "steady-state current". I can see where on some equipment the measurement of a steady state current/power may not be possible. In those cases I assume it can be calculated. Now, on a more practical note regarding the Rating on the equipment and the NEC 125% rule on the plug, our NRTL says that if the equipment's current rating is within 80% of the plug rating then we have to provide them with the maximum continuous or maximum average current rating of the equipment. Our NRTL says that to avoid confusion in addition to the steady state current rating we can also include the Max. Continuous or Max. Average current rating on our equipment. During inspections this helps to determine if the correct plug and branch circuit is being used and it can aid our customers in determining facility power requirements and HVAC needs. Our situation is similar to the original poster's. We have one piece of equipment that draws 28 amps steady-state when you first turn it on while heaters are warming up in a small furnace which may take 20-30 minutes. Then the current throttles down and runs continuously drawing around 17 amps to maintain the furnace temperature. We use a 10AWG power cord with a NEMA 30A twistlock plug. We have RATED the equipment 28 amps. However, when our product is installed at some customer locations, the Electrician or local inspector will rightly so question the 28 amp rating and the use of a 30 amp plug. So we are often asked what the "max. continuous current" is of the equipment. Once we say it is 17 amps, everything is ok. A CSA engineer has told us that we can include the continuous or average current rating on our equipment in addition to the steady-state current rating to eliminate having to provide this information to the field. The original poster asked if it is ok to rate a product 24A for North America and 32A for Europe. If the equipment is the same and you use the same method to determine your RATING shouldn't your product have the same rating regardless of the market you sell it in? For North America, as long as your product's continuous current is less than 80% of the plug rating you should be ok. The Other Brian -----Original Message----- From: Ted Eckert [mailto:ted.eck...@microsoft.com] Sent: Saturday, August 09, 2014 11:46 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] FW: IEC 62368-1 rated AC input connector amperage differs from North America You are correct. There is no definition for continuous input current in the National Electrical Code. The Code assumes that the definition of input current is covered in each product's safety standard. Equipment either needs to be Listed by a Nationally Recognized Test Laboratory to the appropriate product standard or the local inspector gets to make his or her own determination of what is the proper input current rating. Most manufacturers choose to get their product tested and Listed. Ted Eckert Compliance Engineer Microsoft Corporation ted.eck...@microsoft.com The opinions expressed are my own and do not necessarily reflect those of my employer. -----Original Message----- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Saturday, August 9, 2014 8:09 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] FW: IEC 62368-1 rated AC input connector amperage differs from North America In message <90b959e8e6ef491999a2e9d8a3cbf...@dm2pr03mb383.namprd03.prod.outlook.com> , dated Sat, 9 Aug 2014, Ted Eckert <ted.eck...@microsoft.com> writes: >NFPA 70, the National Electrical Code (NEC), Article 100 defines >"Continuous Load" as "A load where the maximum current is expected to >continue for 3 hours or more". Thank you. Does that mean that there is no formal definition of 'continuous input current' of a load? -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Quid faciamus nisi sit? John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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Thank you. - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <emcp...@radiusnorth.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
