Can anyone explain or speculate as to WHY the NEC does not appear to allow cord connection of stationary/fixed equipment because it's a perfectly "legal" way of connection in the UK (and probably other countries), and is regularly done with items like central heating boilers, instantaneous water heaters and so on (provided that the cord outlet is fitted with a manually-operable d/p isolating switch, generally incorporating a fuse, to enable it to be completely isolated )?
John Allen W. London, UK -----Original Message----- From: Ted Eckert [mailto:ted.eck...@microsoft.com] Sent: 29 July 2014 14:13 To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] NRTL / OSHA interpretation of UL60950 clause 3.2.3 The United States national differences are based off of NFPA 70, also known as the National Electrical Code or NEC. In theory, all NRTLs are obligated to ensure that the products they approve to UL 60950-1 or UL 60950-22 comply with NEC. Not all NRTLs are as strict about it, but it is possible that the NRTL in question is properly reading the NEC. NFPA 70 Section 400 covers flexible cords and cables. Section 400.7 covers permitted uses and 400.8 lists prohibited uses. You may be able to use 400.7(6) or 400.7(8) to argue for a flexible cord on your product. If not, 400.7(10) may be a possibility, but you would need to review section 645, Information Technology Equipment and chapter 8, Communication Systems, to see if there is something that would allow flexible cord on your product. 400.7 Uses Permitted. (A) Uses. Flexible cords and cables shall be used only for the following: (1) Pendants (2) Wiring of luminaires (3) Connection of portable luminaires, portable and mobile signs, or appliances (4) Elevator cables (5) Wiring of cranes and hoists (6) Connection of utilization equipment to facilitate frequent interchange (7) Prevention of the transmission of noise or vibration (8) Appliances where the fastening means and mechanical connections are specifically designed to permit ready removal for maintenance and repair, and the appliance is intended or identified for flexible cord connection (9) Connection of moving parts (10) Where specifically permitted elsewhere in this Code I have run into a few cases where an NRTL has allowed a flexible cord connection on a product based on a liberal interpretation of the NEC, yet the local electrical inspector then prohibited the product from being connected because it did not comply with the NEC. The prohibition of flexible cord connections for many products is a historical artifact of the NEC. There was a safety basis long ago, but I'm not sure that I could argue that the rationale is still valid. I'm not arguing that the NEC is right or wrong. This is only what I have experienced from similar issues. 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: Tuesday, July 29, 2014 2:31 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] NRTL / OSHA interpretation of UL60950 clause 3.2.3 In message <6af0cb17eff94b31971265f87afee...@thhste15d1be4.hs20.net>, dated Tue, 29 Jul 2014, Charlie Blackham <char...@sulisconsultants.com> writes: >I was going off memory, and have had another look at the standard: > >The equipment is "Stationary Equipment" as it is not "movable >equipment" due to it being bolted to a mast or pole. However, >Stationary Equipment" can be pluggable in UL60950-1 - I'm just >wondering whether it has to be permanently connected in UL60950-22 >(which I don't have) I don't see anything in the IEC version of 60950-22 that demands permanent connection. The clause is short but not easy to interpret as it refers to 3.3 of IEC 60950-1 for one case and IEC 60364 for another, but the cases are not easy to distinguish. -- 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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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>
