Hi Nic:
"Opposite polarity" is a term I first came across in UL standards. As you have, I understood "polarity" applied to D.C. UL applied the term to A.C., meaning the opposite (or return) pole of the supply. Here's a definition of "polarity" from the net: polarity (p??'lær?t?) - n 1. the condition of having poles 2. the condition of a body or system in which it has opposing physical properties at different points, esp magnetic poles or electric charge 3. the particular state of a part of a body or system that has polarity: an electrode with positive polarity 4. the state of having or expressing two directly opposite tendencies, opinions, etc So, while many of us think in terms of D.C. polarity, the definition can equally apply to A.C. polarity where L and N are the poles and are of opposite polarity. Best regards, Rich -----Original Message----- From: Nic Johnson Sent: Thursday, September 27, 2012 8:43 AM To: [email protected] Subject: Meaning of "opposite polarity" in IEC 61010-1 Ed. 3 Edition 3 of IEC 61010-1 added the following line to Section 9.6.1; "A minimum of BASIC INSULATION is required between MAINS-connected parts of opposite polarity on the supply side of the overcurrent protection device." Does anyone know what "opposite polarity" is supposed to mean in this context? It doesn't appear to be in reference to DC voltage or plugs. Does this refer to multi-phase system only? Any clarifications or interpretations would be appreciated. Nic Johnson NCEE Labs 402-323-6233 - ---------------------------------------------------------------- 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 <[email protected]> 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://listserv.ieee.org/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: Jim Bacher <[email protected]> David Heald <[email protected]> - ---------------------------------------------------------------- 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 <[email protected]> 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://listserv.ieee.org/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: Jim Bacher: <[email protected]> David Heald: <[email protected]>
