In message <[email protected]>, dated Wed, 6 Oct 2010, Mark Gandler <[email protected]> writes:
>let's assume there are 120VAC traces on the top layer of the PCB (AC >comes in from a detachable power cord) Right next to the trace (<1mm) >there is a plastic stand with metal screw (washer build-in) in it. >metal washer lays on top of the AC trace, separated only by the mask. >Screw is not connected to any grounds or circuits or any other >conducted part. It is untouchable to the user side. > >Is where any safety concern? Product is evaluated under 60950. One >thing came to my mind, is a plastic standoff, probably should be able >to support high voltage? is it valid concern? any others? While it's not a violation of the standard, it's a worry. What happens if someone puts a long screw into the stand-off in error? A possible solution, if you can't move anything, is to use a plastic PCB stand-off that doesn't need a screw; they have a split peg that goes through the board and expands two spines above the board. There is also a type that has a threaded peg and a plastic nut. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK If at first you don't succeed, delegate. But I support unbloated email http://www.asciiribbon.org/ - ---------------------------------------------------------------- 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.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. 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]>
