Rich
Your first para is effectively what I was trying to say (obviously not effectively!) because, as you said, the internal wiring then need only be able to cope with the normal-condition current and any overcurrents from internal faults (such as a short to ground in Class I equipment) would be prevented by the fuse(s) rupturing before there is any damage to the wiring or other components. Also, it might be worth reminding folks that single-pole fusing is OK for defined-polarity mains supply systems (e.g. the UK, and some N.American systems) if it is in the Line/Live/”Hot” conductor, but not in undefined-polarity systems as found on the European Continent and many other regions/countries – those need double-pole fusing or else there is the risk that the unfused lines will have to carry the full mains-supply prospective fault current in the event of a similar fault condition with a reversed-polarity connection. If the latter configuration can apply, then you cannot reduce in the wiring size unless the equipment is Class II Double Insulated. All this is outlined in 60950 and other standards. John E Allen W.London, UK From: Richard Nute [mailto:[email protected]] Sent: 23 June 2016 18:47 To: [email protected] Subject: Re: [PSES] insulated wires AFAIK, that requirement does not apply if a correctly fused appliance inlet is used because that should allow smaller gauge wiring from its outlet terminals – and that is quite common (or at least it was) for 60950 equipment. Wire rating (in 60950 equipment) is based on normal-condition current, not fault-condition current. (Think conductor size in wall-warts.) Wire rating based on fuse rating would imply that wire ratings would be based on fault-condition current. Rich - ---------------------------------------------------------------- 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://www.ieee-pses.org/list.html (including how to unsubscribe) <http://www.ieee-pses.org/list.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://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 <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
