I used to manage an outside EMI test lab. About 15 years ago I remember one well known client who needed to pass FCC Class B but his product utilized a plastic case (not metalized nor conductive finish, but fully plastic). When his product failed he started adding [many] ferrite beads to the culprit internal I/O cable until his product was 10 dB below the limit. Then he started taking them off one by one until the product was about 2 dB below the limit. When I inquired why remove the beads and reduce margin his response was cost and that his management would not be pleased with him because he had added cost to the product.
Just an interesting story. Manny Barron EMC/EMI Engineer Northrop Grumman Corp. San Jose, California -----Original Message----- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Thomas Cokenias Sent: Friday, March 30, 2012 12:24 PM To: ri...@ieee.org Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: "Compliance costs too much." I used to work at FCC Lab and they have ways of getting your attention. One story as I remember it: Back in the mid 80's there was an IBM clone computer company named (I believe) Columbia Data Products, at the time located in Columbia MD, They were heavily advertising their latest computer soon to come on the market, had a warehouse full of product just waiting for the FCC certification process to be completed at the FCC Lab (also in Columbia MD). Alas, they failed sample testing several times, and the application was denied. And they could not come up with a way to retrofit the design, much less the products in the warehouse, so that they would meet the Part 15 limits. The FCC issued a non-compliance letter. The local paper had an article showing the destruction of the warehouse samples, with photo of bulldozers crushing and otherwise rendering useless all the would- be merchandise. Pretty impressive. I was working in private sector lab when this happened - the article was a great sales tool with customers who balked at the expense of doing all that testing... Tom Cokenias T.N. Cokenias Consulting P.O. Box 1086 El Granada CA 94018 On Mar 29, 2012, at 8:23 PM, Richard Nute wrote: > I once worked with an EMC engineer who measured the performance of > himself and his time by the cost of the components that were used in > the equipment solely for the purpose of EMC control. > > His objective was to reduce the cost of compliance by advising > designers of careful layout so as to minimize the need for EMC > components. > > Safety is a bit different because many safety components are also > functional components. > Nevertheless, a ground wire can be eliminated if double-insulation is > employed. In this example, a cost trade-off between the power cord > and the extra insulation. But, these days, most primary circuit > designs are indeed double-insulated as transformers simply don't use > internal shields. > > Enclosures... only needed for primary circuits and secondary circuits > exceeding 30 V. (Yes, you still want an enclosure, but not for > safety!) > > Etc. So, compliance should not cost too much. > > I look forward to your comments on compliance costing too much. > > > 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 > <emc-p...@ieee.org> > > 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 <emcp...@radiusnorth.net> > Mike Cantwell <mcantw...@ieee.org> > > For policy questions, send mail to: > Jim Bacher: <j.bac...@ieee.org> > David Heald: <dhe...@gmail.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 <emc-p...@ieee.org> 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 <emcp...@radiusnorth.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.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 <emc-p...@ieee.org> 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 <emcp...@radiusnorth.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
