Hi Carl, The 2 tests have different purposes, as explained in the -2 rationale doc. I think it's difficult to definitively state that either the S.1 test or the S.2 test is more stringent than the other. Note that the pass/fail criteria are different for the 2 tests, with only S.2 requiring that no additional holes develop.
Note that a fire enclosure that does not meet PIS separation requirements of 6.4.8.4 would have to comply with both S.1 and S.2, be rated V-1 and comply with S.2, or be rated V-0 or better (no additional test). On Wed, May 6, 2020 at 11:46 AM John Woodgate <[email protected]> wrote: > This is the sort of thing that can easily happen in a huge document. It is > extremely difficult, especially where there is a chain of forward and back > cross references, and text pushed off from its primary context to multiple > annexes, to ensure internal consistency. > Best wishes John Woodgate OOO-Own Opinions Only www.woodjohn.uk Rayleigh, > Essex UK MAY THE VIRUS NOT BE WITH YOU > On 2020-05-06 18:35, Carl Newton wrote: > > I'm wondering if any list members can explain the rationale behind > 62368-1, in sections 6.4.8.2.2 and 6.8.8.4. I'm looking at the 2014 > edition. > > Clause 6.4.6, Control of fire spread in a PS3 circuit, states that, "*Fire > spread in PS3 circuits shall be controlled by applying all of the following > supplementary safeguards*:". In that clause it includes, "*by providing > a fire enclosure as specified in 6.4.8.*" > > Clause 6.4.8.2.2, * Requirements for a fire enclosure*, states "*For > circuits where the available power does not exceed 4 000 W (see 6.4.1), a > fire enclosure shall comply with the requirements of Clause S.1.*" That > clause then goes on to say that V-1 is acceptable.... > > Clause (6.4.8.4) is addressing "Separation of a PIS from a fire enclosure > and a fire barrier" and is only requiring the application of the S.2 flame > test, which I believe is less demanding in that only a 60 s flame is > applied rather than three steps up to 120 s for the S.1 test method. > Clause 6.4.8.4 then goes on to state that a V-0 material is excluded from > the requirement. So unless I'm mistaken, this clause 6.4.8.4 (which > addresses separation) is requiring a lesser flame requirement than S.1, yet > goes on to exclude V-0, but not V-1. > > I don't see the rationale. I must be missing something here. The most > fundamental question in my mind here is why does 6.8.8.4 allow the S.2 test > method? > > Thanks, > > Carl > - > ---------------------------------------------------------------- > > 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) <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]> > -- Scott Aldous | Regulatory Compliance Manager | [email protected] | 650-253-1994 - ---------------------------------------------------------------- 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]>
