Brian is right; all NEC rules apply to the installation. In this case, the practical solution could be a sub-panel for the house loads that are served by the inverter, but there are several ways it could be done. You are looking inside the inverter (and the inverter safety standard) for the solution. Look outside the box. Colorado Brian
---------- Original Message ---------- From: "Brian O'Connell" <oconne...@tamuracorp.com> To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] grounding of output of solar inverter Date: Tue, 16 Feb 2016 17:27:37 +0000 Reference articles 250 and 690 of the NEC (NFPA70). Canada and Mexico code similar. Brian From: Bo�tjan Glavi� [mailto:bostjan.gla...@siq.si] Sent: Monday, February 15, 2016 9:05 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] grounding of output of solar inverter Dear experts, Is anyone familiar with UL 1741? I am dealing with solar inverter for US market. Solar inverter can operate in utility interactive mode (feeding the grid) or in� a standalone mode where only homeloads are supplied by inverter (anti-islanding relays are open, due to problems with the grid). When anti-islanding relays are open, I have an issue of grounding the neutral conductor of output for homeloads. How can this grounding be achieved? Clause 19.2 does not allow grounding inside the unit (or I have �understood it incorrectly and it only prohibits fixed connection) and clause 19.3 requires that output is grounded. Below is extract from the standard. Any idea? I think it is the same issue as with UPS. 19.2 An inverter intended to be utility-interactive shall not have a direct/solid electrical connection between any output ac conductor and the enclosure. 19.3 Other than as specified in 19.2, each ac output circuit shall have a grounded conductor. The ac output circuit conductor to be grounded shall be as follows: a) Single-phase, 2-wire - one conductor. b) Single-phase, 3-wire - the neutral conductor. c) Multiphase system having one wire common to all phases - the common conductor. d) Multiphase system in which one phase is used as in item (b) - the neutral conductor. 19.4 The conductor specified in 19.3 is to be connected by a bonding jumper connected between the grounded conductor and: a) The enclosure of a metal-enclosed unit, or b) For a nonmetallic enclosed unit, the metal chassis that is bonded to the equipment grounding conductor or terminal. See 18.2.1. Thank you for your support. Best regards, Bostjan - ---------------------------------------------------------------- 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 <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com> - ---------------------------------------------------------------- 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 <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
