Joe et al, I may be splitting hair here, but there is another requirement that wasn't legislated, nor is it harm-based, but was based on consumer complaints to the FCC about the quality of jacks and sockets (IIRC, these were the words of the late Bill von Alven): the requirement for minimum gold plating thickness.
Cheers, N. Shani Ottawa, ON On Fri, Feb 10, 2012 at 20:39, Joe Randolph <[email protected]>wrote: > On 2/10/2012, Mark Gandler wrote: > > My question for TIA-968-A is: how can something be compliant with all the > criteria in this standard "in spite of" been totally destructed? Does it > mean it is ok if power adapter or power supply is dead or entire product, > including voice port can be out? > > Test Lab did the 2.5kV test, power adapter stopped producing DC, but no > arcing, burning or enclosure breach. Lab concluded the failure. > > > Hi Mark: > > The other responses you have received are all correct. For clarification, > I would just add that the reason is that FCC Part 68 is a "harms-based" > standard, as opposed to Telcordia GR-1089 and many other standards that are > "performance-based." FCC Part 68 does not concern itself with whether your > product works, or with how well it works. It only concerns itself with the > ways in which your product can interfere with the proper functioning of the > network. > > Years ago, one of my colleagues liked to point out that "a block of wood > will pass FCC Part 68." This is surprising but true, and I often quote > this when trying to explain to clients that FCC Part 68 approval does not > say much about the quality or usefulness of a product. > > In the early days of FCC Part 68, the "harms-based" philosophy was pretty > clear. Functional failure as a result of the lightning test was fine as > long as the equipment became essentially an open circuit presented to the > phone line. In subsequent years the requirement to survive the "Type B" > surge was added based on the argument that failures could "harm" the > network by causing unnecessary service calls to the service providers from > customers complaining that their phone service had stopped. This change > was controversial at the time because it stretched the definition of a > network "harm." Failure in response to the more severe "Type A" surge > remains allowable. > > Another functional requirement that appears in FCC Part 68 is for hearing > aid compatibility for equipment that has a handset, but that is a result of > Federal legislation, not the harms-based philosophy behind the standard. > > Note that even though the Type B surge and the hearing aid compatibility > performance requirements appear in an otherwise purely harms-based FCC Part > 68, the previously mentioned block of wood will pass both of those tests. > > By the way, I agree with a previous response that the FCC Part 68 2500 > volt surge is fairly modest. If your power supply is really being damaged > by this surge, you will likely have a high level of field failures with > this product, even if you do manage to persuade the test lab that the > product passes FCC Part 68. You would be well advised to look into the > failure mode and make changes to improve the performance. For good field > reliability, I recommend a self-imposed requirement of 5000 volts for > common mode (longitudinal) surges on tip/ring. > > ** > > ** Joe Randolph > Telecom Design Consultant > Randolph Telecom, Inc. > 781-721-2848 (USA) > http://www.randolph-telecom.com > - ---------------------------------------------------------------- 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]>
