While there is a distance difference between Class A and Class B, it is not the distance that defines the Class, it is the Class that defines the distance. The definition of a Class B is similar, but not exactly the same as for EN. Class B part 15 digital devices are defined as " A digital device that is marketed for use in a residential environment notwithstanding use in commercial, business and industrial environments." A Class A digital device is "A digital device that is marketed for use in a commercial, industrial or business environment, exclusive of a device which is marketed for use by the general public or is intended to be used in the home." This only means that a Class B can be approved for both residential and commercial environments, but a Class A is only approved for a commercial, industrial or business environment but not approved for residential.
Currently the rules are very specific about the year of CISPR 22 that can be used. 15.38 specifically states that the reference to CISPR pub 22 only applies to the 1997 third edition version. Also, CFR47 does not recognize nor allow use of EN55022 in any year. While differences can be minute, it is only the legally referenced document that can be used to show compliance. Dennis Ward Senior Certification Engineer PCTEST This communication and its attachments contain information from PCTEST Engineering Laboratory, Inc., and is intended for the exclusive use of the recipient (s) named above. It may contain information that is confidential and/or legally privileged. Any unauthorized use that may compromise that confidentiality via distribution or disclosure is prohibited. Please notify the sender immediately if you receive this communication in error, and delete it from your computer system. Usage of PCTEST email addresses for non-business related activities is strictly prohibited. No warranty is made that the e-mail or attachment(s) are free from computer virus or other defect. Thank you. -----Original Message----- From: Sykes, Bob [mailto:bob.sy...@gilbarco.com] Sent: Wednesday, June 04, 2014 10:58 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] radiated emissions testing may understate actual emissions, an example using a class D stereo amp Charlie, FCC Class B "protection distance" is 3m, where Class A is 10m. This establishes their relationship. Class B = X dBuV measured at 3m, and Class A = X dBuV @ 10m. (where X = X) >EN 55022 Class B is for domestic environment which is "an environment where the use of broadcast radio and television receivers may be expected within a distance of 10m or the apparatus concerned". --------------------------------------------------- Rick, AM is older than the FCC, but they are making noise (pun intended) about revitalizing it. https://apps.fcc.gov/edocs_public/attachmatch/DOC-323370A1.pdf While LEDs are quiet, any mains powered LED lamp involves some form of pulsed current and EMI. LED lamps are regulated under FCC Part 15. I tried to use them (LED floods) in my shielded enclosure with dismal results. For those interested; This article is mainly about visual flicker, but the same principles apply to noise generation. http://www.digikey.com/en-US/articles/techzone/2012/jul/characterizing-and-m inimizing-led-flicker-in-lighting-applications Here's a discussion of the RFI problem more from a regulatory perspective. http://www.emcrules.com/2011/07/radio-interference-from-led-lighting.html -Bob Sykes -----Original Message----- From: Rick Busche [mailto:rick.bus...@qnergy.com] Sent: Wednesday, June 04, 2014 1:26 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] radiated emissions testing may understate actual emissions, an example using a class D stereo amp Do we still have AM? Someone once called that was Ancient Modulation. :) I suspect that in a few years fluorescent lamps will give way to LED technology. As a side note, do LED lamps create EMI concerns? -----Original Message----- From: Richard Nute [mailto:ri...@ieee.org] Sent: Wednesday, June 04, 2014 11:02 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] radiated emissions testing may understate actual emissions, an example using a class D stereo amp On 6/4/2014 9:47 AM, Mike Violette wrote: "Class B limits are amazingly conservative, to which large populations of devices ascribe." Try using an ordinary AM radio beside a compact fluorescent lamp as on a beside table. - ---------------------------------------------------------------- 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://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 <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. 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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://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 <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://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 <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>
