How often is a second insulation being used? - Mostly never. Just as in a Class 1, you would hope never to need the earth. The whole point of both methods of protection is that no hazard arises in the event of a single insulation fault.
People who don't know what the symbol means are hopefully not going about undertaking electrical repairs or testing product. The symbol is of some use to those who do carry out such work. John C _____ From: Scott Xe [mailto:[email protected]] Sent: 31 July 2013 15:32 To: [email protected] Subject: [PSES] Class II products Just want to know some history about class II safety protection and appreciate your sharing knowledge. Class II products have two levels of insulation: basic and supplementary insulations. Each insulation is safe to prevent from electrical shock in normal use. Why does a product need two levels of insulation in its lifespan? How often is a second insulation being used? Nine out ten people do not know the meaning of class II symbol. What is main purpose to have a double square symbol on class II products? Thanks and regards, Scott - ---------------------------------------------------------------- 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]>
